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  • 51.
    Carlson, Thomas
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    The Life of A.R.T: Storing and anonymizing user data from public profiles2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this work we present an implementation of the t-closeness first microaggregation algorithm into a Python program called ART-Analytics. The project requires that user data that it collects from Instagram be anonymized and stored somewhere in a secure location. Over the course of this work an individual test version was created and then implemented into the existing software upon when it was finished. Evaluations of this work were done by calculating the SSE of the algorithm using test data, and whether or not the goals of the project were achieved as a result of this work. Testing and analysis show that the algorithm works well when used with attributes that have a low variance as the basis for the algorithm, and that it fulfills the needs of the project. 

  • 52.
    Colliander, Henrik
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Prestandajämförelse mellan WireGuard och OpenVPN med Raspberry Pi 32019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Historically, private communications between two remote offices were established by using a dedicated link, also known as a leased line.

    There are some huge drawbacks with this solution, the costs are often unreasonable when you want to maintain private communications between offices after expanding the company to different countries, thus the solution is only viable for large companies. Leased lines also have low flexibility and requires a lot of time and resources to install.

    A better solution to this problem is to make use of virtual private networks (VPNs). A VPN is a private network that is established over a public infrastructure between two nodes, such as the Internet. The virtual private network created between the nodes is called a tunnel where the payload often is entirely encrypted to ensure confidentiality.

    This study was made to compare the performance of two different open source VPN protocols, the older but reliable OpenVPN and a more recent one called WireGuard which has the goal to eventually replace OpenVPN and IPSec according to their website.

    Experiments were done in a lab environment using the two different VPN-solutions running on a Raspberry Pi 3 to evaluate and compare the performance by measuring throughput, packet loss, delay and jitter. The results showed that WireGuard had better performance overall compared to OpenVPN. However, considering WireGuard currently is in an early stage of development, implementations should mainly be used for personal use at your own risk. If you want to use an open source VPN protocol, OpenVPN is still an excellent choice and a reliable solution.

  • 53.
    Daher, Amir
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Nadjati-Yazdi, Artin
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Optimization of warehouse logic and structure2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Products flow in and out of different warehouses all over the world every day all the time, while the technology is improving, warehouses remain as they are unless major developments occur in the industry which require the modern warehouses to follow. Major changes in warehouses cost a fortune for the companies which require the owners to find changes that cost as little as possible while resulting in as high efficiency in the warehouse as possible. The purpose of this project is to find ways to optimize the current logic in the Warehouse Management System named Warehouse Administration Service System or WASS. By analyzing the WASS-systems database, reading the WASS-manual, creating tools to visualize the warehouse both theoretically and practically, interviewing workers, then shortcomings and optimizations can be found. The resultis that the current logic in the warehouse is very unoptimized by analysing the warehouse with the help of visualizing the warehouse and feedback from an interview. Improvements are suggested from analysing the heatmap and through visualizing the issues the improvements can be implemented. By creating a visualization of the optimal structure which can be used as areference for implementing a better structure in the actual production. The visualization tool and the heatmaps can help future warehouses that log goods inwards and outwards find shortcomings in their A,B,C-structure and improve their warehouse logic.

  • 54.
    Dahlman, Victor
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Persson, Ludwig
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Digitalisering av ett ticketsystem för restaurangbranschen2021Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    The project set out to create and configure a system that could be connected to an existing ticket-system within the restaurant businesses. A problem within the restaurant business that can be solved with the help of digitalization is the usage and cost of physical tickets. With this system this problem can be remedied.

    By connecting the ticket-machine with a Raspberry Pi via a serial-link the data that was originally meant to be sent to the ticket printer can now be picked up by the Raspberry Pi and be processed within the device. The data that is received by the Raspberry Pi is converted via a program made with Python3 and then stored in a MySQL-database. A webserver that is running on the Raspberry Pi can display the now digitalized ticket on any web browser capable machine, for example an iPad.

    There is now a prototype that can receive, process, and store the data as well as display it via a web-based interface, on any capable device. The prototype was tested in a production environment and performed after the demands that had been set. The project was completed and both the restaurant personnel as well as the developers were satisfied, and the project was considered a success.

  • 55.
    Darpö, Erik
    et al.
    Nagoya University, Graduate School of Mathematics, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan (JPN).
    Nystedt, Patrik
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Von-Neumann Finiteness and Reversibility in some Classes of Non-Associative Algebras2021In: Algebras and Representation Theory, ISSN 1386-923X, E-ISSN 1572-9079, Vol. 24, p. 1245-1258Article in journal (Refereed)
    Abstract [en]

    We investigate criteria for von-Neumann finiteness and reversibility in some classes of non-associative algebras. Types of algebras that are studied include alternative, flexible, quadratic and involutive algebras, as well as algebras obtained by the Cayley–Dickson doubling process. Our results include precise criteria for von-Neumann finiteness and reversibility of involutive algebras in terms of isomorphism types of their 3-dimensional subalgebras. © 2020, The Author(s).

  • 56.
    de Blanche, Andreas
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Carlsson, Linnea
    University West, School of Business, Economics and IT, Divison of Informatics.
    Olsson, Anna Karin
    University West, School of Business, Economics and IT, Division of Business Administration.
    Eriksson, Kristina M.
    University West, Department of Engineering Science, Division of Production Systems.
    Belenki, Stanislav
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Lundh Snis, Ulrika
    University West, School of Business, Economics and IT, Divison of Informatics.
    Hattinger, Monika
    University West, Department of Engineering Science, Division of Production Systems.
    Artificial and human aspects of Industry 4.0: an industrial work-integrated-learning research agenda2021In: VILÄR: 9-10 of December, 2021, University West, Trollhättan, 2021Conference paper (Other academic)
    Abstract [en]

    The manufacturing industry is currently under extreme pressure to transform their organizations and competencies to reap the benefits of industry 4.0. The main driver for industry 4.0 is digitalization with disruptive technologies such as artificial intelligence, machine learning, internet of things, digital platforms, etc. Industrial applications and research studies have shown promising results, but they rarely involve a human-centric perspective. Given this, we argue there is a lack of knowledge on how disruptive technologies take part in human decision-making and learning practices, and to what extent disruptive technologies may support both employees and organizations to “learn”. In recent research the importance and need of including a human-centric perspective in industry 4.0 is raised including a human learning and decision-making approach. Hence, disruptive technologies, by themselves, no longer consider to solve the actual problems.

    Considering the richness of this topic, we propose an industrial work-integrated-learning research agenda to illuminate a human-centric perspective in Industry 4.0. This work-in-progress literature review aims to provide a research agenda on what and how application areas are covered in earlier research. Furthermore, the review identifies obstacles and opportunities that may affect manufacturing to reap the benefits of Industry 4.0. As part of the research, several inter-disciplinary areas are identified, in which industrial work-integrated-learning should be considered to enhance the design, implementation, and use of Industry 4.0 technologies. In conclusion, this study proposes a research agenda aimed at furthering research on how industrial digitalization can approach human and artificial intelligence through industrial work-integrated-learning for a future digitalized manufacturing.

    Download full text (pdf)
    VILÄR 2021
  • 57.
    de Blanche, Andreas
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Lundqvist, Thomas
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Node Sharing for Increased Throughput and Shorter Runtimes: an Industrial Co-Scheduling Case Study2018In: Proceedings of the 3rd Workshop on Co-Scheduling of HPC Applications (COSH 2018): Held together with HiPEAC 2018 / [ed] Trinitis, Carsten; Weidendorfer, Josef, 2018, p. 15-20Conference paper (Refereed)
    Abstract [en]

    The allocation of jobs to nodes and cores in industrial clusters is often based on queue-system standard settings, guesses or perceived fairness between different users and projects. Unfortunately, hard empirical data is often lacking and jobs are scheduled and co-scheduled for no apparent reason. In this case-study, we evaluate the performance impact of co-scheduling jobs using three types of applications and an existing 450+ node cluster at a company doing large-scale parallel industrial simulations. We measure the speedup when co-scheduling two applications together, sharing two nodes, compared to running the applications on separate nodes. Our results and analyses show that by enabling co-scheduling we improve performance in the order of 20% both in throughput and in execution times, and improve the execution times even more if the cluster is running with low utilization. We also find that a simple reconfiguration of the number of threads used in one of the applications can lead to a performance increase of 35-48% showing that there is a potentially large performance increase to gain by changing current practice in industry.

    Download full text (pdf)
    COSH2018-deBlanche-Lundqvist
  • 58.
    Dedovic, Edina
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    AR-based Assistance in Woodworking Industry2021Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Augmented Reality head-worn displays are a technology rising in popularity among private individuals but also companies. With this rise comes new possibilities which opens up for new ways of interaction in the real world together with the virtual. This thesis introduces some of these interactions between the real world and the virtual, displayed on the HoloLens platform. It introduces the approach of designing and implementing a system which would be used in the wood working industry, especially aiming for truss assembly productions lines. A proof-of-concept was implemented and evaluated by a pool of testers in four different environments. The evaluation showed that participants were task efficient when understanding what to do, e.g., finding objects and placing them on surfaces using AR-based system. Lastly, the toughest criteria to fulfil was the enjoyments criteria; however, the user study shows that 5 out of 5 users enjoyed working with AR and could see the potential with the technique in their line of work.

  • 59.
    Didricksson, Tobias
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Norlander, Christian
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    IPv4 eller IPv6 för gemene man i Sverige2021Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    This work compares the time it takes to download a website over IPv4 and IPv6 to then be able to conclude about which protocol a regular user should use to get the best user experience. The starting point is the two older works that have been done on this subject, specifically the newest of these because their method was most similar to ours. The idea was to see if the result would be different if we increased the amount of data collected for analysis. Data has been collected over a whole week, which has given a quantity of 16,749 separate measurements made on 100 different web pages. This data has been analyzed and the specific parts that make up a download of a website have been examined in detail and compared between the IP protocols to see where it differs. The result confirmed our idea that there would be a difference between this and last year's work. However, it was IPv4 that performed significantly worse rather than IPv6 performing better. The result of this work is that IPv6 is faster. 

  • 60.
    Djebbar, Fatiha
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Securing IoT data using steganography: A practical implementation approach2021In: Electronics, E-ISSN 2079-9292, Vol. 10, no 21, article id 2707Article in journal (Refereed)
    Abstract [en]

    Adding network connectivity to any “thing” can certainly provide great value, but it also brings along potential cybersecurity risks. To fully benefit from the Internet of Things “IoT” system’s capabilities, the validity and accuracy of transmitted data should be ensured. Due to the constrained environment of IoT devices, practical security implementation presents a great challenge. In this paper, we present a noise-resilient, low-overhead, lightweight steganography solution adequate for use in the IoT environment. The accuracy of hidden data is tested against corruption using multiple modulations and coding schemes (MCSs). Additive white Gaussian noise (AWGN) is added to the modulated data to simulate the noisy channel as well as several wireless technologies such as cellular, WiFi, and vehicular communications that are used between communicating IoT devices. The presented scheme is capable of hiding a high payload in audio signals (e.g., speech and music) with a low bit error rate (BER), high undetectability, low complexity, and low perceptibility. The proposed algorithm is evaluated using well-established performance evaluation techniques and has been demonstrated to be a practical candidate for the mass deployment of IoT devices.

    Download full text (pdf)
    Electronics
  • 61.
    Djebbar, Fatiha
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Nordström, Kim
    Cybersecurity Product Compliance Group,Stockholm (SWE).
    A Comparative Analysis of Industrial Cybersecurity Standards2023In: IEEE Access, E-ISSN 2169-3536, Vol. 11, p. 85315-85332Article in journal (Refereed)
    Abstract [en]

    Cybersecurity standards provide a structured approach to manage and assess cybersecurity risks. They are the primary source for security requirements and controls used by organizations to reduce the likelihood and the impact of cybersecurity attacks. However, the large number of available cybersecurity standards and frameworks make the selection of the right security standards for a specific system challenging. The absence of a comprehensive comparison overlap across these standards further increases the difficulty of the selection process. In situations where new business needs dictate to comply or implement additional security standard, there may be a risk of duplicating existing security requirements and controls between the standards resulting in unnecessary added cost and workload. To optimize the performance and cost benefits of compliance efforts to standards, it is important to analyze cybersecurity standards and identify the overlapping security controls and requirements. In this work, we conduct a comparative study to identify possible overlaps and discrepancies between three security standards: ETSI EN 303 645 v2.1.1 for consumer devices connected to the internet, ISA/IEC 62443-3-3:2019 for industrial automation and control systems, and ISO/IEC 27001:2022 for information security management systems. The standards were carefully chosen for their broad adoption and acceptance by the international community. We intentionally selected standards with different areas of focus to illustrate the significant overlaps that can exist despite being designed for different environments. Our objective is to help organizations select the most suitable security controls for their specific needs and to simplify and clarify the compliance process. Our findings show a significant overlap among the three selected standards. This information can help organizations gain a comprehensive understanding of common security requirements and controls, enabling them to streamline their compliance efforts by eliminating duplicated work especially when meeting the requirements of multiple standards.

    Download full text (pdf)
    fulltext
  • 62.
    Drottz, Linda
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Rizk, Sally
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Sea level rise and land uplift over Fennoscandia and the Baltic Sea: A statistical test2021Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    We have studied the land uplift and the relative sea level in Fennoscandia and the Baltic sea in northern Europe. This area is interesting to study because it has the largest number of land uplift related observations. To observe the past changes in sea level and land uplift, we have used time series from tide gauges and the gravity field and climate experiment, GRACE satellite mission, from various observation points. We have also used data from NKG2016 land up lift model for comparison.

    To statistacally compare land uplift data with sea level change, a regression line was calculated over the various observation points. A t-test was used to see if the differences were significant. The computed rates of uplift from geodetic observations show that change in the region is significant and happens faster inrelation to changes in sea level. In conclusion, there is a rising trend in both land uplift and sea level rates within Fennoscandia and the Baltic Sea.

    This study also shows that GRACE data does not differ from NKG2016 data. From a sustainable economic perspective, this can mean reduced costs, which contributes to more accurate forecasts of rising sea levels in coastal communities.

  • 63.
    Dufin, Sandra
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Anståndsbeslut i enlighet med PBL 9kap. 28 §: innebörd och konsekvenser2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A deferral decision can be made in accordance with PBL Chapter 9 § 28 if a case concerning permit or advance notice is affected by a started planning work. The question of permit will then be decided when the planning work is finished, however, no later than two years from the application being submitted to the building committee. There is no obstacle to start planning work at the same time the deferral decision is made and the purpose of the decision is, according to the legislature, that the building committee should be given the opportunity to start planning work in order to deny an application for an out-of-plan real property or which is in accordance with current detailed development plan or area regulations. This study shows that very few deferral decisions are made in accordance with the legislature's purpose, instead it is many times used with the purpose of waiting for provisions already ongoing planning work. In cases where the application for permit does not accord with the current detailed development plan or area regulations the deferral decision is positive for the real property owner, given the possibility that the permit can be submitted in accordance with ongoing planning work. If the application for permit instead either applies to an out-of-plan real property or is in accordance with the applicable detailed development plan or area regulations, there is a risk that the deferral decision will lead to denied application for permit. If a decision to start planning work is taken at the same time as the deferral decision with the reason to deny a specific application for permit, a situation can occur where the application for permit has been preceded by the Land Surveyor that has formed a new property in accordance with the same purpose as the application for permit. In case of a denied permit, this means a complicated situation for the real property owner because the newly formed real property unit will not be possible to build on according to the real property owner's requests. When a real property unit is formed for new construction out-of-plan an advance notice is in most cases necessary before the Land Survey decides. Based on the study's conclusions, a real property owner is recommended to seek advance notice when something is to be done that requires a permit, even if the action is to be done in accordance with the present detailed development plan. When the implementation period for a detailed development plan has expired, there is no guarantee that measures in accordance with the detailed development plan are workable. The fact that the Land Survey will in a larger scale consult with the building committee in real property development within detailed development plan is also something that is discussed in the study, although it would be uncertain if it could lead to a real property development being denied on the grounds, which in this case would not lead to a better solution for the real property owner.

  • 64.
    Eklund, Linda
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Friyta på lika villkor!: En studie av 8 kap. 9 § plan- och bygglagen2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sweden's population is steadily increasing, and cities are densifying. Most of the residents wish to live centrally, where closeness to both jobs and service is located. The densification, in turn, means that more schools and preschools need to be built. In densified cities, the area is shrinking to build on, which results in a higher price on the land. The purpose of the study is to investigate how Sweden's municipalities interpret "sufficiently large free space" in Chapter 8. 9 § 2 of the Planning and Building Act. The study also examines whether the municipalities changed their way of working as the Children's Convention became law on January 1, 2020. The study has used electronic questionnaires sent to Sweden's 290 municipal building departments with a response rate of 44%. Nearly half of the study's respondents use the checklist from Boverket and almost as many also have their own guidelines. A part of the study respondents uses functional programs that follow the curriculum's intentions when planning the school or preschool. The results of the study's survey show that 61% of the respondents follow current research on the size of the free space, which is 30 square meters for students in F-6 and 40 square meters for preschool children. The respondents which not following the common advice from Boverket about free space, developed their own guidelines for the size of the free space. Most of these municipalities set the size of the free space lower than recommended. The result shows that the respondents who do not follow the general advice on free space from Boverket think that the location of the free space weighs heavier than the size and design of the free space. Of the respondents, only 30 have worked with the Convention on the Rights of the Child even before the law came into force. Most of the respondents will start or have started to work more with the Convention on the Rights of the Child when designing school and preschools since the Convention on the Rights of the Child has become law. Although cities are increasingly densified, the current wording in Chapter 8. 9 § 2 The Planning and Building Act has in principle not changed since the building charter. Since the ground today is more attractive and that the Children's Convention has become law, the wording "sufficiently large free area" in Chapter 8. 9 § 2, the Planning and Building Act need to be changed. The law section should contain clarifications on the design and size of the surface to ensure such a large surface area that according to research is suitable for children in school and preschool.

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    fulltext
  • 65.
    Elfving, Erik
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Martinsson, Jacob
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Vad bör tålas vid företagsskada och miljöskada?: en rättsutredning av kvalifikationsgränsen2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Public infrastructure often causes disturbances on the surroundings in terms of noise, vibrations, insight, aesthetic damages, or psychological detriments. Disturbances from the expropriation business may cause damages in terms of decreased market value for the affected property, beyond the decreased value from the loss of land. Surrounding properties may also be affected, in terms of environmental damages. The owners of the affected property may claim compensation for the decreased property value caused by the disturbances.

    To be eligible for compensation the damages should not reasonably be tolerated consideringthe conditions of the location and the general conditions. The legislation does not clearly state any limit in terms of percentage or amount of money required for a disturbance to be significant enough to grant compensation. The limit of qualification for expropriation damages or environmental damages has previously to some degree been treated inconsistentin Swedish legal practice.

    The study describes how the qualification limit varies due to different conditions in previous cases. The purpose of the study is to investigate if the extent or the type of the disturbance affects the limit of qualification. The study has been created using a legal dogmatic methodology, in which the courts intentions with the verdicts has been analyzed. The selection of cases is limited to the preceding courts, supported by a few relevant cases from lower instances. 

    The study infers that the limit of qualification amounts to 5 % of the intact property value, in cases when the disturbance is not considered common on the location or in general. When the disturbance is considered common on the location or in general, the court considers the equitability of the conditions in the case. According to the courts, a significant damage can be a valid cause for compensation. Consequently, the limit of qualification may vary in cases where the disturbance is common on the location or in general. The study finds no support for the previous claim that the limit of qualification is higher for aesthetic disturbances than measurable disturbances such as noise. The result of the study shows that the limit of qualification is the same for damages from different sources, during similar conditions.

  • 66.
    Emilsson, Maria
    et al.
    University West, Department of Health Sciences, Section for nursing - graduate level.
    Ernstson, Ulf
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Gustavsson, Linn
    University West, Department of Engineering Science, Division of Production Systems.
    Svensson, Ann
    University West, School of Business, Economics and IT, Divison of Informatics.
    Sustainable Innovations in Small Enterprises for the Transformation of the Primary Healthcare Sector2020In: Sustainability, ISSN 2071-1050, Vol. 12, no 16, p. 1-19, article id 6391Article in journal (Refereed)
    Abstract [en]

    Small enterprises face multiple and complex challenges when developing digital technologies. The aim of this article is to explore the role of sustainable innovation in small enterprises in relation to the ongoing transformation of the primary healthcare sector. The purpose is to gain understanding of innovation processes within the framework of sustainable development, applied to a local primary healthcare center. Data were collected through seven semi-structured interviews. A qualitative thematic analysis was conducted. Five themes appeared in relation to the ongoing transformation of the primary healthcare sector: (1) The process of sustainable innovation in a long-term perspective; (2) the companies’ views on innovations in healthcare; (3) effects of innovations in healthcare; (4) sustainable product or service development, and (5) the role of collaboration in the innovation process. The companies expressed a positive attitude to new innovations, as a natural part of developing the companies. The article concludes that incremental development of tools in small businesses supports the transformation of processes and services in the primary healthcare sector. Cross-disciplinary teams in collaboration facilitates the necessary learning and the required creation and sharing of knowledge.

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    fulltext
  • 67.
    Engblom, Tove
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Gunnarsson, Lisa
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Lovet på landet: En rättsdogmatisk studie av 9 kap. 6 § PBL2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    When the older planning and building act was replaced in 2011 by todays planning and building act, the paragraph regulating permits exempt buildings actions received some linguistic updates. The updates where intended to simplify and update the interpretation. Any changes in the countryside in how this was supposed to be interpreted was not intended. This thesis examines how multiple Swedish municipalities interpret the permits exempt buildings according to 9 chap. 6 § planning and building act. The examination was done with a survey sent to all Swedish municipalities, which was then put together and the results where compared. To be able to decide if the municipalities have been making correct interpretations this thesis have also made a thorough legal examination of the law and preliminary work.

    9 chap. 6 § planning and building act is a complicated paragraph and cannot be interpreted without reading the preparatory work. Unfortunately, just reading the propositions to the planning and building act is not enough. The preparatory work for older planning and building act must also be read to fully grasp the meaning of the law. The paragraph has gone through multiple updates since 1987, therefor the information has been spread out.

    The permits exempt buildings in this paragraph is aimed at property owners owning houses with one or two families in the countryside that want to erect a small extension for the house or a complimentary building adjacent to the main building. The condition is that there is a house on the property and that the building is of a complementary nature to not dominate over the actual main house. The property owner does not need to report to or consult with the municipality but is rather supposed to judge if the rules are applicable for them self.T

    hat the average citizen, without basic legal education, is supposed to be able to interpret a complicated paragraph like this is troublesome. The consequence of a misjudgement is expensive. Unfortunately, there is not a lot of guidance to be had from the municipalities since our survey shows that almost all Building Department are making incorrect decisions based on interpreting the paragraph incorrectly.

    This thesis shines a light on the problem with assigning a complicated paragraph to be interpreted by the property owners. Furthermore, allowing the municipalities to make their own regulations regarding the interpretation of the law, without accountability to superior government agencies does not make the problems fewer. Our conclusion with this thesis results in that better guidance and stricter demands on the municipalities must be enacted to not place too big of a responsibility on the individual citizen.

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    fulltext
  • 68.
    Ericsson, Niklas
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering. Department of Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, SE–412 96 Gothenburg , Sweden.
    A Framework for Approximation of the Stokes Equations in an Axisymmetric Domain2021In: Computational Methods in Applied Mathematics, ISSN 1609-4840, E-ISSN 1609-9389, Vol. 21, no 4, p. 791-810Article in journal (Refereed)
    Abstract [en]

    We develop a framework for solving the stationary, incompressible Stokes equations in an axisymmetric domain. By means of Fourier expansion with respect to the angular variable, the three-dimensional Stokes problem is reduced to an equivalent, countable family of decoupled two-dimensional problems. By using decomposition of three-dimensional Sobolev norms, we derive natural variational spaces for the two-dimensional problems, and show that the variational formulations are well-posed. We analyze the error due to Fourier truncation and conclude that, for data that are sufficiently regular, it suffices to solve a small number of two-dimensional problems.

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  • 69.
    Eriksson, Aiden
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Unity Engine Machine Learning Agents: Creating bots that solve problems like a human2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Unity Machine Learning Agents is an open-source toolkit designed to allow anyone develop AI and to integrate machine learning AI into their Unity Engine games. The toolkit can be integrated with and ran through the Unity Development Platform where agents and environments can be configured, allowing developers to design scenarios as if they were creating games. This paper evaluates the possibility of replacing traditional bots with agents and what limitations they have. The agents were trained with the toolkits PPO trainerthrough two scenarios, a puzzle and a maze, where the agent’s information input is limited to artificial vision in 2-dimentions.

    The results show that the agents could solve the puzzle and maze, but that they struggle when facing new problems due to the limitations of PPO training when complexity increases unexpectantly. The agents could therefore solve specific problems and they work well as a bot replacement if specialized but cannot at this point replace traditional bots in games where they need specialty in several areas.

  • 70.
    Eriksson, Kevin
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Lunde, Jesper
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Teknikstudie över olika laddningstekniker för elfordon2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Electric vehicles are on a strong rise with increasing sales and larger infrastructure every year. For a fast-growing industry like electric vehicles, it is interesting to look at how they are charged as this affects all owners of electric vehicles. The commercial technologies for electric vehicle charging today are conductive and have been standardized. However, several different standards exist, partly competing with each other. The report describes the major standards of IEC, CCS, CHAdeMO and GB/T, in addition to these, there is also the car manufacturer Tesla with its own standard. The thesis takes a closer look at some development projects to see in which directions the technology is developing. Among other things, conductive transmission via rail in or on the road and transmission by wires above the road, but also upgrading of existing standards. Inductive charging projects are further investigated with static inductive charging stations and dynamic inductive charging while driving. The thesis investigates dynamic inductive charging in deeper detail. There is a lot of research and projects going on, but there are still many problems to solve in order to commercialize the technology. The advantage of inductive charging is that it can be wireless and when the vehicle is charged while driving, fewer stops are required to charge. The technology, on the other hand, has some efficiency issues that can vary greatly depending on how the vehicle is aligned towards the transfer coil. Communication to pay for charging, among other things, is still early in the development, as a very high communication speed is required when charging during travel. The writers view is that the major development and expansion will occur in inductive transmission as well as upgrading of the existing conductive standards. Standardization of the upcoming technologies is considered important in order to avoid creating many incompatible technologies on the roads. Work on standardization of inductive transmission is in progress but is not yet complete.

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  • 71.
    Eriksson, Monica
    et al.
    University West, Department of Health Sciences, Section for health promotion and care sciences.
    Alsén, Pia
    University West, Department of Health Sciences, Section for nursing - graduate level.
    Lycke, Liselott
    University West, Department of Engineering Science.
    Tano, Ingrid
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Aronsson, Gunnar
    Stockholms universitet, Stockholm, Sverige.
    ARK: modell för att systematiskt arbeta med hållbart arbetsliv inom universitet och högskola (UoH)2018In: FALF 2018 - program och abstraktbok / [ed] Per Lindberg, Gävle: University Press , 2018, p. 123-123Conference paper (Refereed)
    Abstract [sv]

    Bakgrund

    Hållbart arbetsliv är idag ledord för arbetslivets förändrade villkor. Inom UoH i Sverige fanns i slutet av 2017 omkring 75 000 anställda varav ca 35 000 inom forskning och undervisning (UKÄ, 2017). Det är en sektor med stor betydelse för samhällsutvecklingen i Sverige. Arbetsmiljön inom sektorn ställer särskilda krav på personalen. Förvånansvärt få studier har gjorts i Sverige om arbetsmiljön för personal inom UoH. Med förebild från Norge implementeras nu för första gången i Sverige en forskningsbaserad (krav-resurs-modellen) och sektorsspecifik ny modell för att systematiskt arbeta med arbetsmiljön, den s.k. Ark-modellen (arbeidsmiljø- og klimaundersøkelser, se figur) vid Högskolan Väst. Arbetsmiljöverkets föreskrift 2015:4 betonar den organisatoriska och sociala arbetsmiljön, vilket väl tillgodoses i denna modell.

    Syfte

    Att systematiskt och långsiktigt arbeta med arbetsmiljön ur ett främjande, förebyggande och rehabiliterande perspektiv på såväl individ- som organisatorisk nivå för att utveckla förhållanden som bidrar till ett hållbart arbetsliv.

    Metod

    Genom KIWEST (Knowledge Intensive Work Environment Survey Target) kartläggs arbetsmiljön utifrån 28 olika dimensioner. Kategorier som belyses är t.ex. sociala, uppgiftsbaserade och organisatoriska resurser samt jobbkrav och tillhörighet till jobbet. Organisatoriska förhållanden mäts med FaktaARK 1 medan genomförda insatser mäts med FaktaARK 2.

    Resultat

    KIWEST sändes till all personal med 20 % anställning eller mer. Utav 539 tillfrågade personer svarade 376, vilket ger en svarsfrekvens på 69,8 %. Resultatet visar att specifikt för sektorn är upplevelsen av tidspress samtidigt som arbetet upplevs som meningsfullt och viktigt. Nu följer analyser, planering, genomförande och utvärdering av insatser på olika nivåer inom högskolan. KIWEST-formuläret sänds till personalen med 3-års intervall. I förbättringsarbetet ingår även att granska och utvärdera genomförandet, därvid ingår även metodutveckling. Förbättringsarbetet sätts in i ett större organisatoriskt perspektiv och är en naturlig del i kvalitetssäkringsprocessen och ledningssystemet. ARK-processen förväntas bidra till teoriutveckling av krav- och resursmodellen samt öka kunskapen om arbetsmiljön inom UoH.

  • 72.
    Eriksson, Tommie
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Damfelt, Christoffer
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Increasing Simulation Performance: Experimental tests of bottlenecks and scalability of LS-DYNA on Tetra Pak HPC-clusters2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Larger companies working with simulations and computing resources, require a lot of resources to execute their jobs. To make simulations less performance heavy, High-Performance Computing (HPC) is often used. HPC clusters implements a parallel algorithm over multiple nodes to speed up and utilize many computers, with this, large simulations that require a lot of resources will not take extensive amounts of time to finish.

    Large simulations can be performance heavy and time consuming and thus cost a lot of money if extra computing resources from outsourcing are needed. Optimizing HPC clusters can reduce extra costs while also decreasing the time it takes to execute jobs.

    With the cooperation of Packaging Material (PM), which is a business unit at Tetra Pak in Lund, Sweden, this thesis aims to understand Multi Parallel Processing (MPP) solvers, investigate Tetra Pak's HPC cluster to confirm that the right hardware and software is available and used as well as selecting and running representative simulation models and runtime parameters commonly used by PM, with the goal of optimizing their HPC clusters.

    Results given in this thesis are based on multiple tests which show that there are improvements that can be made, in both hardware and software. According to the findings in this thesis using newer versions and updated instructions for the processors a performance increase up to 17% is achievable.

  • 73.
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    An optimal design of GNSS interference localisation wireless security network based on time-difference of arrivals for the Arlanda international airport2022In: Journal of Geodetic Science, ISSN 2081-9919, E-ISSN 2081-9943, Vol. 12, no 1, p. 154-164Article in journal (Refereed)
    Abstract [en]

    Today, most of the aircrafts are navigated by global navigation satellite systems (GNSSs). Landing is a dangerous phase of a flight especially when an airport runway is not clearly seen from the aircrafts. In such cases, GNSSs are useful for a safe landing under the circumstances that healthy signals, free of any interference, reach to GNSSs receiver antennas mounted on the aircrafts. This shows the importance of establishing GNSS interference localisation security networks around airports. Designing a good configuration for the points with GNSS antennas at for receiving interference signals is important for a successful localisation of the interference device. Here, the time-difference of the arrivals of an interference signal to such points or anchor nodes (ANs), are used as observables, and a security network with four ANs is optimally designed along the runways of the Arlanda airport to reduce the dilution of precision (DOP) of the network. Our study showed that by such an optimisation, the maximum DOP value can reduce by 50% meaning a significant increase in the probability of a successful interference device localisation.

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  • 74.
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Analysis of the gravity field, direct and inverse problems2022In: Journal of Geodetic Science, ISSN 2081-9919, E-ISSN 2081-9943, Vol. 12, no 1, p. 244-245Article, book review (Refereed)
    Abstract [en]

    This new book deals with, as its titles says, the analysis and process of gravity field of the Earth. The book is mathematically oriented, and the authors have explained how Mathematics is used for local analysis of the gravity field. The basic and required background knowledge, needed for understanding the book, are given in early chapters as well as appendices. They are used for explaining gravity field analysis from measurement surveys, corrections, and processes to direct and inverse problems in exploration Geophysics with interesting exercises, numerical and real examples.

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  • 75.
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Elastic thickness determination based on Vening Meinesz-Moritz and flexural theories of isostasy2018In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 213, no 3, p. 1682-1692Article in journal (Refereed)
    Abstract [en]

    Elastic thickness (Te) is one of mechanical properties of the Earth's lithosphere. The lithosphere is assumed to be a thin elastic shell, which is bended under the topographic, bathymetric and sediment loads on. The flexure of this elastic shell depends on its thickness or Te. Those shells having larger Te flex less. In this paper, a forward computational method is presented based on the Vening Meinesz–Moritz (VMM) and flexural theories of isostasy. Two Moho flexure models are determined using these theories, considering effects of surface and subsurface loads. Different values are selected for Te in the flexural method to see by which one, the closest Moho flexure to that of the VMM is achieved. The effects of topographic/bathymetric, sediments and crustal crystalline masses, and laterally variable upper mantle density, Young's modulus and Poisson's ratio are considered in whole computational process. Our mathematical derivations are based on spherical harmonics, which can be used to estimate Te at any single point, meaning that there is no edge effect in the method. However, the Te map needs to be filtered to remove noise at some points. A median filter with a window size of 5° × 5° and overlap of 4° works well for this purpose. The method is applied to estimate Te over South America using the data of CRUST1.0 and a global gravity model.

  • 76.
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Natural Sciences and Electrical and Surveying Engineering. University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Numerical aspects of EGM08-based geoid computations in Fennoscandia regarding the applied reference surface and error propagation2013In: Journal of Applied Geophysics, ISSN 0926-9851, E-ISSN 1879-1859, Vol. 96, p. 28-32Article in journal (Refereed)
    Abstract [en]

    So far the recent Earth's gravity model, EGM08, has been successfully applied for different geophysical and geodetic purposes. In this paper, we show that the computation of geoid and gravity anomaly on the reference ellipsoid is of essential importance but error propagation of EGM08 on this surface is not successful due to downward continuation of the errors. Also we illustrate that some artefacts appear in the computed geoid and gravity anomaly to lower degree and order than 2190. This means that the role of higher degree harmonics than 2160 is to remove these artefacts from the results. Consequently, EGM08 must be always used to degree and order 2190 to avoid the numerical problems. © 2013 Elsevier B.V.

  • 77.
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    On the approximations in formulation of the Vening Meinesz-Moritz theory of isostasy2017In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 210, no 1, p. 500-508Article in journal (Refereed)
    Abstract [en]

    Different approximations are used in Moho modelling based on isostatic theories. The well-known approximation is considering a plate shell model for isostatic equilibrium, which is an oversimplified assumption for the Earth’s crust. Considering a spherical shellmodel, as used in the Vening Meinesz-Moritz (VMM) theory, is a more realistic assumption, but it suffers from different types of mathematical approximations. In this paper, the idea is to investigate such approximations and present their magnitudes and locations all over the globe. Furthermore, we show that the mathematical model of Moho depth according to the VMM principle can be simplified to that of the plate shell model after four approximations. Linearisation of the binomial term involving the topographic/bathymetric heights is sufficient as long as their spherical harmonic expansion is limited to degree and order 180. The impact of the higher order terms is less than 2 km. The Taylor expansion of the binomial term involving the Moho depth (T) up to second order with the assumption of T-2 = TT0, T-0 is the mean compensation depth, improves this approximation further by up to 4 km over continents. This approximation has a significant role in Moho modelling over continents; otherwise, loss of frequency occurs in the Moho solution. On the other hand, the linear approximation performs better over oceans and considering higher order terms creates unrealistic frequencies reaching to a magnitude of 5 km in the Moho solution. Involving gravity data according to the VMM principle influences the Moho depth significantly up to 15 km in some areas.

  • 78.
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Optimal Configuration for Monitoring Stations in a Wireless Localisation Network Based on Received Signal Strength Differences.2023In: Sensors, E-ISSN 1424-8220, Vol. 23, no 3, article id 1150Article in journal (Refereed)
    Abstract [en]

    A smart city is a city equipped with many sensors communicating with each other for different purposes. Cybersecurity and signal security are important in such cities, especially for airports and harbours. Any signal interference or attack on the navigation of autonomous vehicles and aircraft may lead to catastrophes and risks in people's lives. Therefore, it is of tremendous importance to develop wireless security networks for the localisation of any radio frequency interferer in smart cities. Time of arrival, angle of arrival, time-difference of arrivals, received signal strength and received signal strength difference (RSSD) are known observables used for the localisation of a signal interferer. Localisation means to estimate the coordinates of an interferer from some established monitoring stations and sensors receiving such measurements from an interferer. The main goal of this study is to optimise the geometric configuration of the monitoring stations using a desired dilution of precision and/or variance-covariance matrix (VCM) for the transmitter's location based on the RSSD. The required mathematical models are developed and applied to the Arlanda international airport of Sweden. Our numerical tests show that the same configuration is achieved based on dilution of precision and VCM criteria when the resolution of design is lower than 20 m in the presence of the same constraints. The choice of the pathloss exponent in the mathematical models of the RSSDs is not important for such low resolutions. Finally, optimisation based on the VCM is recommended because of its larger redundancy and flexibility in selecting different desired variances and covariances for the coordinates of the transmitter.

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  • 79.
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Optimization of Basepoint Configuration in Localization of Signal Interference Device2023In: Journal of Surveying Engineering, ISSN 0733-9453, E-ISSN 1943-5428, Vol. 149, no 1, article id 1150Article in journal (Refereed)
    Abstract [en]

    Precise navigation, as a method for guiding vehicles from one point to another, is an important subject these days especially in navigation of aircraft. Global navigation satellite systems (GNSSs) are capable tools for such a purpose. Any intentional or unintentional interference in satellite signals may cause risks of deadly accidents. Therefore, it is tremendously important to control airports or harbors and locate any existing radio frequency interference device. This localization can be done based on measuring time of arrival (TOA), angle of arrival (AOA), or time difference of arrival (TDOA) of signals from the device to sensors or receivers at some basepoints. In this article, a method is proposed based on these arrivals for optimizing the configuration created by these basepoints from a large grid of points covering a control area. Furthermore, a simulation test was performed to verify the theory, and after that a control network was designed and optimized for the international Landvetter Airport of Sweden. Our simulation studies show that when the AOA is used, our optimization is more robust with respect to the control grid resolution. In addition, optimization based on the TDOA improves the coverage over the control area with a significant reduction of error of control points, but because of the special geometric shape of the Landvetter Airport, such an optimization was not successful. 

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  • 80.
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Satellite gravimetry and the solid Earth: mathematical foundations2020Book (Other academic)
    Abstract [en]

    Satellite gravimetry and the solid Earth: mathematical foundations presents the theories behind satellite gravimetry data and their connections to solid Earth. It covers the theory of satellite gravimetry and data analysis, presenting it in a way that is accessible across geophysical disciplines. Through a discussion of satellite measurements and the mathematical concepts behind them, the book shows how various satellite measurements, such as satellite orbit, acceleration, vector gravimetry, gravity gradiometry, and integral energy methods can contribute to an understanding of the gravity field and solid Earth geophysics. Bridging the gap between geodesy and geophysics, this book is a valuable resource for researchers and students studying gravity, gravimetry and a variety of geophysical and Earth Science fields.

  • 81.
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    The Earth’s Gravity Field Role in Geodesy and Large-Scale Geophysics2021In: Geodetic Sciences: Theory, Applications and Recent Developments / [ed] Erol, Bihter & Erol, Serdar, IntechOpen , 2021Chapter in book (Refereed)
    Abstract [en]

    The Earth gravity field is a signature of the Earth’s mass heterogeneities and structures and applied in Geodesy and Geophysics for different purposes. One of the main goals of Geodesy is to determine the physical shape of the Earth, geoid, as a reference for heights, but Geophysics aims to understand the Earth’s interior. In this chapter, the general principles of geoid determination using the well-known methods of Remove-Compute-Restore, Stokes-Helmert and least-squares modification of Stokes’ formula with additive corrections are shortly discussed. Later, some Geophysical applications like modelling the Mohorovičić discontinuity and density contrast between crust and uppermantle, elastic thickness, ocean depth, sediment and ice thicknesses, sub-lithospheric and lithospheric stress, Earthquakes and epicentres, post-glacial rebound, groundwater storage are discussed. The goal of this chapter is to briefly present the roll of gravity in these subjects.

  • 82.
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Work-integrated learning and Surveying Engineering Education2019In: VILÄR 5-6 december 2019, University West, Trollhättan: Abstracts / [ed] Kristina Johansson, Trollhättan: University West , 2019, p. 8-8Conference paper (Other academic)
    Abstract [en]

    Surveying Engineering Education (SEE) programmes are often of three years and the students learn how to model the shape of the Earth's surface by specific instruments, applying mathematics and computer software. They are inherently practically-oriented and majority of their courses contain simulated practical assignments close to the job market. Work-integrated learning (WIL), which is an approach to intentionally involve learners with practical works so that the learn the concepts by using them, is a suitable for SEEs. Different WIL models such as simulated assignment, collaborative learning with help of industry, and cooperative education, are applicable in SEE, which can increase the students' self-confidence, motivation, academic performance, and employability potential in addition to prepare them for working environments. Here, the focus is on the cooperative education in SEE, which is done outside universities. Literatures about WIL lacks attention to SEEs, there is a need for more researches with focus on the state-of-the-actual in this subject rather to see challenges in the work placement of students in business-oriented private sectors. Our literature study and interviews of three graduates from three subsequent graduation years and two students having experience in work placement showed clear supports of the governmental organisations. However, some students experienced difficulties in private companies. The job has been stressful for them and they were sometimes used like labours. Making clear agreements with private companies, clarifying the roles and missions of the students and companies, covering the costs and compensating time are important factors, which need to be considered. Inviting active engineers from companies for performing simulated assignments close to reality at campus will be very helpful for preparing the students for work placement for practical parts of the courses. It is also recommended that cooperative education needs to be performed with a full supervision of university.

  • 83.
    Eshagh, Mehdi
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Ashargie, Andenet
    Bedada, Tulu B.
    Regional recovery of gravity anomaly from the inversion of diagonal components of GOCE gravitational tensor: A Case Study in Ethiopia, Artificial Satellites2018In: Artificial Satellites : he Journal of Space Research Centre of Polish Academy of Sciences, E-ISSN 2083-6104, Vol. 53, no 2, p. 55-74Article in journal (Refereed)
    Abstract [en]

    The tensor of gravitation is traceless as the gravitational field of the Earth is harmonic outside the Earth's surface. Therefore, summation of the 2nd-order horizontal derivatives on its diagonal components should be equal to the radial one but with the opposite sign. The gravity field can be recovered locally from either of them, or even their combination. Here, we use the in-orbit diagonal components of the gravitational tensor measured by the gravity field and steady stateocean circulation explorer (GOCE) mission for recovering gravity anomaly with a resolution of 1°×1° at sea level in Ethiopia. In order to solve the system of equations, derived after discretisation of integral equations, the Tikhonov regularisation is applied and the bias of thi sregularisation is estimated and removed from the estimated gravity anomalies. The errors of the anomalies are estimated and their significance of recovery from these diagonal components is investigated. Statistically, the difference between the recovered anomalies from each scenario isnot significant comparing to their errors. However, their joint inversion of the diagonal components improved the solution by about 1 mGal. Furthermore, the inversion processes arebetter stabilised when using errors of the input data compared with its exclusion, but at the penalty of degradation in accuracy of the estimates.

  • 84.
    Eshagh, Mehdi
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Berntsson, Jenny
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    On quality of NKG2015 geoid model over the Nordic countries2019In: Journal of Geodetic Science, ISSN 2081-9919, E-ISSN 2081-9943, Vol. 9, no 1, p. 97-110Article in journal (Refereed)
    Abstract [en]

    The NKG2015 geoid model covers the Nordic and Baltic countries and has been computed based on the least-squares modification of Stokes’ formula with additive corrections method. New and precise terrestrial, airborne and shipborne gravimetric measurements, the recent global gravity model of the gravity field and steady-state ocean circulation explorer (GOCE) and detailed digital terrain models over each territory have been used for computing this new geoid model. Some estimates for the error of this model have been roughly presented by comparing it with the global navigation satellite system(GNSS) data over each country. In this paper, our goal is to have a closer look at the relative error of this model by performing some statistical tests and finding the proper corrective surface for absorbing the systematic errors over each country. Our main assumption is realisticity of the errors of GNSS/levelling data and we will investigate its consequences in estimating the error of the geoid model. Our results show that the 4-parameter corrective surface is suitable for modelling the systematic trends of the differences between the gravimetric and GNSS geoid heights in Sweden, Denmark and Finland, but a filtered discrepancies by a confidence interval of 95% should be used for Sweden. A 7-aparameter model is suitable for the filtered discrepancies with the confidence interval of 95% in Norway. Based on the selected corrective surface and our newly developed regional iterative variance estimator, the confidence interval for the error of NKG2015 geoid model in Sweden, Denmark and Norway yielded 0-6.5 mm, 1.8-5.2 mm, 14.8-17.7 mm, respectively with a confidence level of 95%. We could not estimate the geoid error in Finland because the given error of the GNSS/levelling heights is significantly larger than the size of residuals. Based on the selected corrective surfaces and our presented local variance estimator, the average error of geoid becomes 3.6, 2.4, 8.8 and 5.8 mm with a confidence interval of 68%, respectively, over Sweden, Denmark, Norway and Finland.

  • 85.
    Eshagh, Mehdi
    et al.
    University West, Department of Engineering Science, Division of Natural Sciences and Electrical and Surveying Engineering. University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Ebadi, Sahar
    K.N.Toosi University of Technology, Tehran, Iran.
    A strategy to calibrate errors of Earth gravity models2014In: Journal of Applied Geophysics, ISSN 0926-9851, E-ISSN 1879-1859, Vol. 103, no April, p. 215-220Article in journal (Refereed)
    Abstract [en]

    In this paper, three independent Earth gravity models (EGMs) ofGO_CONS_GCF_2_TIM_R4, AIUB-GRACE03S and ULux_CHAMP2013s are combined to degree and order 120. The geoid models of these EGMs are computed and compared with the Global Positioning System (GPS) and levelling data over Fennoscandia. We found that the simple mean of these geoid models is closer to the GPS/levelling data than their weighted mean. This means that errors of the EGMs are not properly estimated as they are used in the weighted mean solution. We develop a method based on solving a nonlinear condition adjustment model to calibrate the errors so that the result of weighted mean becomes the same as that of the simple mean. Numerical results show slight changes in the errors of GRACE03S but large ones in those of GO_CONS_GCF_2_TIM_R4 and ULux_CHAMP2013s. Furthermore, the weighted mean solution considering the calibrated errors and some additional constraints is better than GOCO03S to degree and order 120 over Fennoscandia.

  • 86.
    Eshagh, Mehdi
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering. K. N. Toosi University of Technology, Faculty of Geodesy and Geomatics Engineering, Tehran, Iran (IRN).
    Fatolazadeh, Farzam
    Université de Sherbrooke, Departement de Geomatique Appliquée, Sherbrooke, Québec, Canada (CAN).
    Tenzer, Robert
    Hong Kong Polytechnic University, Department of Land Surveying and Geo-Informatics, Hong Kong (HKG).
    Lithospheric stress, strain and displacement changes from GRACE-FO time-variable gravity: case study for Sar-e-Pol Zahab Earthquake 20182020In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 223, no 1, p. 379-397Article in journal (Refereed)
    Abstract [en]

    Temporal variations in the Earth’s gravity field can be used for monitoring of lithospheric deformations. The network of continuously operating gravity stations is required for this purpose but a global coverage by such network is currently extremely sparse. Temporal variations in long-wavelength part of the Earth’s gravity field have been, however, observed by two satellite missions, namely the Gravity Recovery And Climate Experiment (GRACE) and the GRACE Follow-On (GRACE-FO). These satellite gravity observations can be used to study long-wavelength deformations of the lithosphere. Consequently, considering the lithosphere as a spherical elastic shell and solving the partial differential equation of elasticity for it, the stress, strain and displacement inside the lithosphere can be estimated. The lower boundary of this shell is assumed to be stressed by mantle convection, which has a direct relation to the Earth’s gravity field according to Runcorn’s theory. Changes in gravity field lead to changes in the sublithospheric stress and the stress propagated throughout the lithosphere. In this study, we develop mathematical models in spherical coordinates for describing the stress propagation from the sublithosphere through the lithosphere. We then organize a system of observation equations for finding a special solution to the boundary-value problem of elasticity in the way that provides a stable solution. In contrast, models presented in previously published studies are ill-posed. Furthermore, we use constants of the solution determined from the boundary stresses to determine the strain and displacements leading to these stresses, while in previous studies only the stress has been considered according to rheological properties of the lithosphere. We demonstrate a practical applicability of this theoretical model to estimate the stress–strain redistribution caused by the Sar-e-Pol Zahab 2018 earthquake in Iran by using the GRACE-FO monthly solutions.

  • 87.
    Eshagh, Mehdi
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Johansson, Filippa
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Karlsson, Lenita
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Horemuz, Milan
    Royal Institute of Technology, Stockholm, Sweden.
    A case study on displacement analysis of Vasa warship2018In: Journal of Geodetic Science, ISSN 2081-9919, E-ISSN 2081-9943, Vol. 8, no 1, p. 43-54Article in journal (Refereed)
    Abstract [en]

    Monitoring deformation of man-made structures is very important to prevent them from a risk of collapse and save lives. Such a process is also used for monitoring change in historical objects, which are deforming continuously with time. An example of this is the Vasa warship, which was under water for about 300 years. The ship was raised from the bottom of the sea and is kept in the Vasa museum in Stockholm. A geodetic network with points on the museum building and the ship's body has been established and measured for 12 years for monitoring the ship's deformation. The coordinate time series of each point on the ship and their uncertainties have been estimated epoch-wisely. In this paper, our goal is to statistically analyse the ship's hull movements. By fitting a quadratic polynomial to the coordinate time series of each point of the hull, its acceleration and velocity are estimated. In addition, their significance is tested by comparing them with their respective estimated errors after the fitting. Our numerical investigations show that the backside of the ship, having highest elevation and slope, has moved vertically faster than the other places by a velocity and an acceleration of about 2 mm/year and 0.1 mm/year2, respectively and this part of the ship is the weakest with a higher risk of collapse. The central parts of the ship are more stable as the ship hull is almost vertical and closer to the floor. Generally, the hull is moving towards its port and downwards

  • 88.
    Eshagh, Mehdi
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Pitonak, Martin
    University of West Bohemia, NTIS - The New Technologies for the Information Society, Faculty of Applied Sciences, Pilsen, Czech Republic.
    Tenzer, Robert
    Hong Kong Polytechnic University, Department of Land Surveying and Geo-Informatics, Hong Kong.
    Lithospheric elastic thickness estimates in central Eurasia2019In: Terrestrial, Atmospheric and Oceanic Science, ISSN 1017-0839, E-ISSN 2223-8964, Vol. 30, no 1, p. 73-84Article in journal (Refereed)
    Abstract [en]

    We estimate the elastic thickness of a continental lithosphere by using two approaches that combine the Vening Meinesz-Moritz (VMM) regional isostatic principle with isostatic flexure models formulated based on solving flexural differential equations for a thin elastic shell with and without considering a shell curvature. To model the response of the lithosphere on a load more realistically, we also consider lithospheric density heterogeneities. Resulting expressions describe a functional relation between gravity field quantities and mechanical properties of the lithosphere, namely Young’s modulus and Poisson’s ratio that are computed from seismic velocity models in prior of estimating the lithospheric elastic thickness. Our numerical study in central Eurasia reveals that both results have a similar spatial pattern, despite exhibiting also some large localized differences due to disregarding the shell curvature. Results show that cratonic formations of North China and Tarim Cratons, Turan Platform as well as parts of Siberian Craton are characterized by the maximum lithospheric elastic thickness. Indian Craton, on the other hand, is not clearly manifested. Minima of the elastic thickness typically correspond with locations of active continental tectonic margins, major orogens (Tibet, Himalaya and parts of Central Asian Orogenic Belt) and an extended continental crust. These findings generally support the hypothesis that tectonically active zones and orogens have a relatively small lithospheric strength, resulting in a significant respond of the lithosphere on various tectonic loads, compared to a large lithospheric strength of cratonic formations.

  • 89.
    Eshagh, Mehdi
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Pitoňák, Martin
    University of West Bohemia, NTIS-The New Technologies for the Information Society, Faculty of Applied Sciences, Pilsen, Czech Republic.
    Elastic Thickness Determination from on-orbit GOCE Data and CRUST1.02019In: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 176, no 2, p. 685-696Article in journal (Refereed)
    Abstract [en]

    Elastic thickness (Te) is a parameter representing the lithospheric strength with respect to the loading. Those places, having large values of elastic thickness, flexes less. In this paper, the on-orbit measured gravitational gradients of the Gravity field and steady-state Ocean Circulation Explorer (GOCE) mission are used for determining the elastic thickness over Africa. A forward computational method is developed based on the Vening Meinesz-Moritz (VMM) and flexural theories of isostasy to find a mathematical relation between the second-order derivative of the Earth’s gravity field measured by the GOCE satellite and mechanical properties of the lithosphere. The loading of topography and bathymetry, sediments and crystalline masses are computed from CRUST1.0, in addition to estimates of laterally-variable density of the upper mantle, Young’s modulus and Poisson’s ratio. The second-order radial derivatives of the gravitational potential are synthesised from the crustal model and different a priori values of elastic thickness to find which one matches the GOCE on-orbit gradient. This method is developed in terms of spherical harmonics and performed at any point along the GOCE orbit without using any planar approximation. Our map of Te over Africa shows that the intra-continental hotspots and volcanoes, such as Ahaggar, Tibesti, Darfur, Cameroon volcanic line and Libya are connected by corridors of low Te. The high values of Te are mainly associated with the cratonic areas of Congo, Chad and the Western African basin.

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  • 90.
    Eshagh, Mehdi
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Steinberger, Bernhard
    Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam, Germany & Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Postboks 1028 Blindern, Oslo, Norway.
    Tenzer, Robert
    Hong Kong Polytechnic University, Department of Land Surveying and Geo-Informatics, 11 Yuk Chai Rd, Hung Hom, Hong Kong.
    Tassara, Andrés
    Universidad de Concepción, Departamento de Ciencias de la Tierra, Facultad de Ciencias Químicas, Victor Lamas 1290, Concepción, Chile.
    Comparison of gravimetric and mantle flow solutions for sub-lithopsheric stress modeling and their combination2018In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 213, no 2, p. 1013-1028Article in journal (Refereed)
    Abstract [en]

    Based on Hager and O’Connell’s solution to mantle flow equations, the stresses induced by mantle convection are determined using the density and viscosity structure in addition to topographic data and a plate velocity model. The solution to mantle flow equations requires the knowledge of mantle properties that are typically retrieved from seismic information. Large parts of the world are, however, not yet covered sufficiently by seismic surveys. An alternative method of modeling the stress field was introduced by Runcorn. He formulated a direct relation between the stress field and gravity data, while adopting several assumptions, particularly disregarding the toroidal mantle flow component and mantle viscosity variations. A possible way to overcome theoretical deficiencies of Runcorn’s theory as well as some practical limitations of applying Hager and O’Connell’s theory (in the absence of seismic data) is to combine these two methods. In this study, we apply a least-squares analysis to combine these two methods based on the gravity data inversion constraint on mantle flow equations. In particular, we use vertical gravity gradients from the Gravity field and steady state Ocean Circulation Explorer that are corrected for the gravitational contribution of crustal density heterogeneities prior to applying a localized gravity-gradient inversion. This gravitational contribution is estimated based on combining the Vening Meinesz-Moritz and flexural isostatic theories. Moreover, we treat the non-isostatic effect implicitly by applying a band-limited kernel of the integral equation during the inversion. In numerical studies of modeling, the stress field within the South American continental lithosphere we compare the results obtained after applying Runcorn and Hager and O’Connell’s methods as well as their combination. The results show that, according to Hager and O’Connell’s (mantle flow) solution, the maximum stress intensity is inferred under the northern Andes. Additional large stress anomalies are detected along the central and southern Andes, while stresses under most of old, stable cratonic formations aremuch less pronounced or absent. A prevailing stress-vector orientation realistically resembles a convergent mantle flow and downward currents under continental basins that separate Andean Orogeny from the Amazonian Shield and adjacent cratons. Runcorn’s (gravimetric) solution, on the other hand, reflects a tectonic response of the lithosphere to mantle flow, with the maximum stress intensity detected along the subduction zone between the Nazca and Altiplano plates and along the convergent tectonic margin between the Altiplano and South American plates. The results also reveal a very close agreement between the results obtained from the combined and Hager and O’Connell’s solutions. © The Author(s) 2018. Published by Oxford University Press on behalf of The Royal Astronomical Society.

  • 91.
    Eshagh, Mehdi
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Tenzer, R.
    Department of Land Surveying and Geo-Informatics, Hong Kong(HKG) Polytechnic University, Hong Kong.
    The temporal viscoelastic model of flexural isostasy for estimating the elastic thickness of the lithosphere2021In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 227, no 3, p. 1700-1714Article in journal (Refereed)
    Abstract [en]

    The (effective) elastic thickness of the lithosphere defines the strength of the lithosphere with respect to a load on it. Since the lithosphere is buoyant on a viscous mantle, its behaviour with respect to a load is not fully elastic, but rather viscoelastic. Fennoscandia is a well-known area in the world where the lithosphere has not yet reached its isostatic equilibrium due to the ongoing uplift after the last glacial period at the end of the Pleistocene. To accommodate for this changing property of the lithosphere in time, we present the flexural model of isostasy that accommodates temporal variations of the lithospheric flexure. We then define a theoretical model for computing the elastic thickness of the lithosphere based on combining the flexural and gravimetric models of isostasy. We demonstrate that differences between the elastic and viscoelastic models are not that significant in Fennoscandia. This finding is explained by a relatively young age of the glacial load when compared to the Maxwell relaxation time. The approximation of an elastic shell is then permissible in order to determine the lithospheric structure and its properties. In this way, the elastic thickness can be estimated based on combining gravimetric and flexural models of isostasy. This approach takes into consideration the topographic and ocean-floor (bathymetric) relief as well as the lithospheric structural composition and the post-glacial rebound. In addition, rheological properties of the lithosphere are taken into consideration by means of involving the Young modulus and the Poisson ratio in the model, both parameters determined from seismic velocities. The results reveal that despite changes in the Moho geometry attributed to the glacial isostatic adjustment in Fennoscandia are typically less than 1 km, the corresponding changes in the lithospheric elastic thickness could reach or even exceed ±50 km. The sensitivity analysis confirms that even small changes in input parameters could significantly modify the result (i.e. the elastic thickness estimates). The reason is that the elastic thickness estimation is an inverse problem. Consequently, small changes in input parameters can lead to large changes in the elastic thickness estimates. These findings indicate that a robust estimation of the elastic thickness by our method is possible if comprehensive information about structural and rheological properties of the lithosphere as input parameters are known with a relatively high accuracy. Otherwise, even small uncertainties in these parameters could result in large errors in the elastic thickness estimates.

  • 92.
    Eshagh, Mehdi
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering. K. N. Toosi University of Technology, Department of Geodesy, Tehran, Iran (IRN); Islamic Azad University, Department of Geology, Karaj branch, Iran (IRN).
    Tenzer, Robert
    Hong Kong Polytechnic University,Department of Land Surveying and Geo-Informatics, Hong Kong (HKG).
    Elastic thickness of the Iranian lithosphere from gravity and seismic data2020In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 774, article id 228186Article in journal (Refereed)
    Abstract [en]

    We estimate the (effective) elastic thickness of the Iranian lithosphere (and adjoining tectonic plates) by using the approach that combines the Vening Meinesz-Moritz's (VMM) regional isostatic principle with the isostatic flexural model formulated based on solving a flexural differential equation for a thin elastic shell. To model the response on a load more realistically, we also consider the lithospheric density structure. The resulting expression describes a functional relation that links gravity field and mechanical properties of the lithosphere. The Young modulus and the Poisson ratio are computed from seismic velocity data in prior of estimating the lithospheric elastic thickness. The presented results reveal that the estimated elastic thickness closely resembles a regional tectonic configuration associated with the extensional tectonism along the Red Sea-Gulf Rift System, the continental collision of the Arabian and Eurasian plates, and the subduction along the Makran Subduction Zone. Seismically and volcanically active convergent tectonic margins of the Zagros and Kopeh Dagh Fold and Thrust Belts further extending along the Makran Accretionary Complex are characterised by a low lithospheric strength, with the elastic thickness typically less than ∼30 km. These small values of the elastic thickness are in a striking contrast to much larger values within most of the Central Iranian Blocks. According to our estimate, local maxima there reach ∼70 km in the Tabas micro-block. The elastic thickness of the Turan and Arabian Platforms reaches maxima of ∼100 km. These results generally support the hypothesis that tectonically active zones and orogens have a relatively low strength, resulting in a significant response of the lithosphere on various tectonic loads, compared to a significant strength of old cratonic formations. Interestingly, however, we observe a striking contrast between a low strength of the Arabian Shield compared to a high strength of the Arabian Platform. A possible explanation of this finding could be given by a different thermal regime of the Arabian lithosphere, controlled mainly by a mantle upwelling and a consequent extensional tectonism along the Red Sea-Gulf Rift System. © 2019

  • 93.
    Eskina, Ksenija
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Watoot, Ali
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    En jämförelsestudie mellan punktmoln framställda med UAS-fotogrammetri och Laserdata NH på ett industriområde i Västsverige2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Generation of Digital Terrain Model (DTM) is an essential part in project planning in questions related to spatial planning. Basis for the DTM is the point cloud which obtains initial data from the measurement. DTM can be used in different areas, accepted quality level is depending on the assignment for which DTM is produced. UAS-photogrammetry is one of the methods which is used for DTM generation, but it is possible to produce DTM from point cloud originated from Laserdata NH. A DTM is a model representing entirely terrain surface, where the data used for its generation gathers from measuring of a certain object.

    The purpose of this study accomplished at Department of Engineering Science at University West was to compare two different methods for point cloud generation as a basis for DTM. First point cloud generated comes from own measurement with UAS-photogrammetry and second is a point cloud from acquired Laserdata NH. The goal of the comparison is to examine if it is possible to replace UAS-photogrammetry with the cost effective Laserdata NH in the project for the industrial area (Lödöse varvet) in Lilla Edet municipality, and if it is possible to replace it generally.

    With help of Agisoft Metashape software the point cloud from UAS-measurement with DJI Phantom 4 Advanced was generated and then compared to Laserdata NH point cloud in CloudCompare program.

    Result of this study is showing that it is possible to replace UAS-photogrammetry with Laserdata NH in this specific and others similar projects which have same purpose and certain decided precision since point clouds are not significantly deviating from each other. While it is not possible to replace them generally, as UAS-photogrammetry obtains higher precision concerning point cloud generation compared to accuracy that Laserdata NH has in its measurements.

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  • 94.
    Fassihi, Oktay
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Pavic, Mladen
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Särskilda skäl för strandskyddsdispens2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Shore protection is present to preserve the public access to the area and to protect the biodiversity. This leads to restrictions on how to use the land. To build facilities, amongst other things, you need to apply for a dispensation from the municipality. The purpose of this report is to investigate how special circumstances for a shore protection dispensation according to chapter 7. 18 c § of the Swedish environmental code is examined in court and how the paragraph is applied in practice. The report is based on the following three issues:

    1. What are the underlying arguments for requesting a shore protection dispensation for special circumstances?

    2. How does the Land and Environment Court and Land and Environment Court of Appeal judge the assessments made in accordance with chapter 7. 18 c § of the Swedish environmental code.

    3. How are the dispensation rules applied in practice by municipalities and county administration boards?

    The study is based on court decisions in the Land and Environment Court of Appeal and written interviews from municipalities and county administrative boards. The result shows the distribution between granted and denied dispensation in cases that have been raised in the Land and Environment Court of Appeal and presentation of cases that it is explained how the Land and Environment Court of Appeal has assessed. The result also shows a quantitative compilation of the interview responses we have received. The discussion section will try to answer the questions that the study is based on by contrasting the answers from the municipalities and county administrative boards with each other. It will also illustrate the most common assessments made by the Land and Environment Court of Appeal when a dispensation case is appealed. The discussion will also touch the subject how the relation between the municipalities and the county administrative boards are seen.

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  • 95.
    Fatolazadeh, Farzam
    et al.
    Université de Sherbrooke, CARTEL, Département de Géomatique Appliquée, Sherbrooke, Québec, Canada (CAN).
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering. K. N. Toosi University of Technology, Department of Geodesy, Tehran, Iran (IRN).
    Goïta, Kalifa
    Université de Sherbrooke, CARTEL, Département de Géomatique Appliquée, Sherbrooke, Québec, Canada (CAN).
    A new approach for generating optimal GLDAS hydrological products and uncertainties2020In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 730, article id 138932Article in journal (Refereed)
    Abstract [en]

    This study proposes a new approach that can be used to generate the optimal surface state information and associated uncertainties from the estimates provided by the six land surface models used by the Global Land Data Assimilation System (GLDAS). The Förstner and best quadratic unbiased variance component estimators are used simultaneously with the least-squares method to calculate optimal values and the associated uncertainties. To demonstrate the concept, the research focused on three GLDAS hydrological products, namely soil moisture (SM), snow water equivalent (SWE), and canopy water (CAN) over the Canadian Prairies. When the Förstner estimator is applied, the estimated SM and SWE differ from their corresponding mean values by 26 mm and 9 mm respectively. Almost similar result was found with the best quadratic estimator. The estimated maximum uncertainties of each component including SM, SWE and CAN vary from year to year (e.g. 35 mm in 2006, 12 mm in 2007 and 2009 and 0.1 mm in 2001, respectively). The uncertainties of the total water storage (TWS) are almost similar to that of SM, which contributes more importantly to TWS in the area considered. The results obtained by the two proposed estimators were compared to the waterGAP hydrological models (WGHM), and to the Gravity Recovery and Climate Experiment (GRACE) terrestrial water storage anomalies. The optimal SWE anomalies generated from GLDAS using the proposed approach show a maximum correlation of r = 0.97 with the WGHM SWE anomalies. The optimal TWS anomalies have a correlation of r = 0.91 with WGHM, and r = 0.71 with GRACE. However, the correlation jumps to r = 0.81 when GRACE TWS is corrected for groundwater signals (with a mean RMSE of 8.5 mm). The RMSE and mean absolute error between our proposed methods and WGHM and GRACE are better than those obtained with each individual LSM or their average value. No significant mean bias error is observed in each case. Finally, the analysis of the time-lag characteristics of the resonance period between the results and their coherence was done by using a cross wavelet transform and a wavelet coherence analysis.

  • 96.
    Fatolazadeh, Farzam
    et al.
    Centre d'applications et de recherches en télédétection (CARTEL), Département de Géomatique appliquée, Université de Sherbrooke, Sherbrooke, Québec (CAN).
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering. Centre d'applications et de recherches en télédétection (CARTEL), Département de Géomatique appliquée, Université de Sherbrooke, Sherbrooke, Québec (CAN).
    Goïta, Kalifa
    Centre d'applications et de recherches en télédétection (CARTEL), Département de Géomatique appliquée, Université de Sherbrooke, Sherbrooke, Québec (CAN).
    New spectro-spatial downscaling approach for terrestrial and groundwater storage variations estimated by GRACE models2022In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 615, no Part A, article id 128635Article in journal (Refereed)
    Abstract [en]

    The study proposes a new mathematical method, referred to as spectral combination, to downscale Gravity Recovery And Climate Experiment (GRACE) observations. The goal is to improve the spatial resolution of GRACE from 1̊ to 0.25̊, based upon available hydrological variables. First, a new approach based upon condition adjustment is proposed to estimate uncertainties related to hydrological variables. Second, a spectral-spatial estimator is developed to derive downscaled Total Water Storage Anomalies (TWSA) by optimally combining GRACE models and hydrological variables. Last, groundwater storage anomalies (GWSA) are derived from the downscaled TWSA. The proposed spectral combination approach was tested over the Canadian Prairies by considering GRACE data and required Global Land Data Assimilation System (GLDAS) variables for February 2003 to December 2016. The results reveal greater details in TWSA after spatial downscaling. Quantitatively, retrieved downscaled GWSA were validated using 75 unconfined in situ piezometric wells that were distributed across the Province of Alberta. A correlation of 0.80, with an RMSE of 11 mm, was obtained after downscaling with all wells over the validation area. These results are better than those obtained before downscaling (correlation of 0.42, with an RMSE of 21.4 mm), demonstrating that the proposed approach is successful. 

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  • 97.
    Fatolazadeh, Farzam
    et al.
    Département de Géomatique Appliquée, Université de Sherbrooke, Sherbrooke, (CAN).
    Eshagh, Mehdi
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering. Département de Géomatique Appliquée, Université de Sherbrooke, Sherbrooke, (CAN).
    Goïta, Kalifa
    Département de Géomatique Appliquée, Université de Sherbrooke, Sherbrooke, (CAN).
    Wang, Shusen
    Canada Centre for Remote Sensing, Natural Resources Canada, Ottawa, (CAN).
    A New Spatiotemporal Estimator to Downscale GRACE Gravity Models for Terrestrial and Groundwater Storage Variations Estimation2022In: Remote Sensing, E-ISSN 2072-4292, Vol. 14, no 23Article in journal (Refereed)
    Abstract [en]

    This study proposes a new mathematical approach to downscale monthly terrestrial water storage anomalies (TWSA) from the Gravity Recovery and Climate Experiment (GRACE) and estimates groundwater storage anomalies (GWSA) at a daily temporal resolution and a spatial resolution of 0.25° × 0.25°, simultaneously. The method combines monthly 3° GRACE gravity models and daily 0.25° hydrological model outputs and their uncertainties in the spectral domain by minimizing the mean-square error (MSE) of their estimator to enhance the quality of both low and high frequency signals in the estimated TWSA and GWSA. The Global Land Data Assimilation System (GLDAS) was the hydrological model considered in this study. The estimator was tested over Alberta, Saskatchewan, and Manitoba (Canada), especially over the Province of Alberta, using data from 65 in-situ piezometric wells for 2003. Daily minimum and maximum GWS varied from 14 mm to 32 mm across the study area. A comparison of the estimated GWSA with the corresponding in-situ wells showed significant and consistent correlations in most cases, with r = 0.43–0.92 (mean r = 0.73). Correlations were >0.70 for approximately 70% of the wells, with root mean square errors <24 mm. These results provide evidence for using the proposed spectral combination estimator in downscaling GRACE data on a daily basis at a spatial scale of 0.25° × 0.25°.  

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  • 98.
    Ferizi, Fatlum
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Kutsomihas, Rickard
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Molnhonungsfällan: en studie om attacker på molntjänsteleverantörsbelägna virtuella maskiner2020Independent thesis Basic level (professional degree), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    This thesis is about installing honeypots on different providers cloud based virtual machines, gathering the data from the honeypots and comparing the data between the providers, and analyse it with regards to differences and similarities in attacks.

    The study focuses on three of the largest cloud based VM providers: Google Cloud, Microsoft Azure and Digital Ocean.

    The honeypots used for the study are Cowrie, Elastichoney, Dionea and the sensor p0f, along with the deployment tool MHN and the data analytics tool Splunk.

    The information gathering process was performed over the period of 11 days, on the dates 2020-07-28 – 2020-08-08, with a total of 240 hours of data collection.

  • 99.
    Forsberg, Felix
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Planering för pandemisäkrad Stadsplanering: En studie över hur stadsbyggnadsprojekt arbetar med att förebygga spridning av pandemier.2022Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study examines how two Swedish municipalities treat and work with managing Covid-19 (SARS-CoV-2) also known as the Coronavirus in their respective municipalities and how they plan to prevent future spread of infection. In modern society there is a problem with sustainable solutions. Effectivisation and modernisation have contributed to push the development of society forward. Sustainable development has become a handy tool for the planning of infrastructure that is being used for prioritizing environmental, social and economical aspects to create a better future for future generations. In the wake of developments, pandemics have become less common in recent decades. Now that a global pandemic is spreading to a large extent, the established order in society is threatened, which clarifies shortcomings in society's resilience.

    The study applies a qualitative method for collecting and analyzing the material collected for the studies, which largely consists of interviews, public documents and literary works. This study identified the problems and opportunities that arise for the two municipalities'organization regarding the handling of the Covid-19 pandemic (SARS-CoV-2). These studies highlight the municipalities' views and their perception of how the pandemic will reform urban planning regarding the physical environment, infrastructure, existence and what consequences these changes may entail. Changes that in the opinion of the municipalities may reform urban planning and life are presented in the studies.

    The two exemplified municipalities believe that potential changes for future urban planning are speculative and impossible to predict, their view is that a change will take place in society as a result of the pandemic. The result of the studies is that the development in society has taken place more markedly during the pandemic and these consequences may influence many different parts of society in the long term. The adjustment that may be required to adapt to the new world may require major changes in how we humans live our lives but also in the development that governs how cities are shaped.

  • 100.
    Forsström, Claes
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Redundans med Rapid Spanning-Tree vs. Flex Links2018Independent thesis Basic level (professional degree), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    In networks where network connectivity is crucial, redundancy is needed. To prevent loops [10] from happening, a number of different protocols are used.

    In this report, Rapid Spanning-Tree Protocol and Flex Links are compared. The purpose is to investigate how the protocol works, the convergence time between the protocols, and if there is some kind of delay from the switch.

    The measurements show that the switches are waiting for some kind of timer before it con-siders a link down after it is physically unplugged. However, if the interface on the switch is shutdown, there is no delay. The results also show that Rapid Spanning Tree can be faster than Flex Links if the link interruption occurs close to a blocked port, otherwise Flex Links converge faster. However, Flex Links cannot see link interruptions beyond its own links, which limiting its area of use.

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