To Örebro University

oru.seÖrebro University Publications
Change search
Refine search result
1234567 51 - 100 of 2072
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 51.
    Alhashimi, Anas
    University of Baghdad, Baghdad, Iraq.
    The application of auto regressive spectrum modeling for identification of the intercepted radar signal frequency modulation2012In: Inventi Impact - Telecom, ISSN 2249-1414, Vol. 2012, no 3Article in journal (Refereed)
    Abstract [en]

    In the Electronic Warfare receivers, it is important to know the type of modulation of the intercepted Radar signals (MOP modulation on pulse). This information can be very helpful in identifying the type of Radar present and to take the appropriate actions against it. In this paper, a new signal processing method is presented to identify the FM (Frequency Modulation) pattern from the received Radar pulses. The proposed processing method based on Auto Regressive Spectrum Modelling used for digital modulation classification [1]. This model uses the instantaneous frequency and instantaneous bandwidth as obtained from the roots of the autoregressive polynomial. The instantaneous frequency and instantaneous bandwidth together were used to identify the type of modulation in the Radar pulse. Another feature derived from the instantaneous frequency is the frequency rate of change. The frequency rate of change was used to extract the pattern of the frequency change. Results show that this method works properly even for low signal to noise ratios.

  • 52.
    Alhashimi, Anas
    et al.
    Örebro University, School of Science and Technology. Luleå University of Technology, Luleå, Sweden.
    Del Favero, Simone
    Varagnolo, Damiano
    Luleå University of Technology, Luleå, Sweden.
    Gustafsson, Thomas
    Luleå University of Technology, Luleå, Sweden.
    Pillonetto, Gianluigi
    Bayesian strategies for calibrating heteroskedastic static sensors with unknown model structures2018In: 2018 European Control Conference (ECC), IEEE, 2018, p. 2447-2453Conference paper (Refereed)
    Abstract [en]

    This paper investigates the problem of calibrating sensors affected by (i) heteroskedastic measurement noise and (ii) a polynomial bias, describing a systematic distortion of the measured quantity. First, a set of increasingly complex statistical models for the measurement process was proposed. Then, for each model the authors design a Bayesian parameters estimation method handling heteroskedasticity and capable to exploit prior information about the model parameters. The Bayesian problem is solved using MCMC methods and reconstructing the unknown parameters posterior in sampled form. The authors then test the proposed techniques on a practically relevant case study, the calibration of Light Detection and Ranging (Lidar) sensor, and evaluate the different proposed procedures using both artificial and field data.

  • 53.
    Alhashimi, Anas
    et al.
    Automatic Control Group at Computer Science, Electrical and Space Engineering, Luleå, University of Technology, Luleå, Sweden.
    Hostettler, Roland
    Automatic Control Group at Computer Science, Electrical and Space Engineering, Luleå, University of Technology, Luleå, Sweden.
    Gustafsson, Thomas
    Automatic Control Group at Computer Science, Electrical and Space Engineering, Luleå, University of Technology, Luleå, Sweden.
    An Improvement in the Observation Model for Monte Carlo Localization2014In: Proceedings of the 11th International Conference on Informatics in Control, Automation and Robotics - Volume 1: ICINCO / [ed] Joaquim Filipe, Oleg Gusikhin, Kurosh Madani and Jurek Sasiadek, SciTePress , 2014, p. 498-505Chapter in book (Refereed)
    Abstract [en]

    Accurate and robust mobile robot localization is very important in many robot applications. Monte Carlo localization (MCL) is one of the robust probabilistic solutions to robot localization problems. The sensor model used in MCL directly influence the accuracy and robustness of the pose estimation process. The classical beam models assumes independent noise in each individual measurement beam at the same scan. In practice, the noise in adjacent beams maybe largely correlated. This will result in peaks in the likelihood measurement function. These peaks leads to incorrect particles distribution in the MCL. In this research, an adaptive sub-sampling of the measurements is proposed to reduce the peaks in the likelihood function. The sampling is based on the complete scan analysis. The specified measurement is accepted or not based on the relative distance to other points in the 2D point cloud. The proposed technique has been implemented in ROS and stage simulator. The result shows that selecting suitable value of distance between accepted scans can improve the localization error and reduce the required computations effectively.

    Download full text (pdf)
    An Improvement in the Observation Model for Monte Carlo Localization
  • 54.
    Alhashimi, Anas
    et al.
    Control Engineering Group, Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology, Luleå, Sweden; Department of Computer Engineering, University of Baghdad, Baghdad, Iraq.
    Pierobon, Giovanni
    Department of Information Engineering, University of Padova, Padova, Italy.
    Varagnolo, Damiano
    Control Engineering Group, Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology, Luleå, Sweden.
    Gustafsson, Thomas
    Control Engineering Group, Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology, Luleå, Sweden.
    Modeling and Calibrating Triangulation Lidars for Indoor Applications2018In: Informatics in Control, Automation and Robotics: 13th International Conference, ICINCO 2016 Lisbon, Portugal, 29-31 July, 2016 / [ed] Kurosh Madani, Dimitri Peaucelle, Oleg Gusikhin, Springer, 2018, p. 342-366Chapter in book (Refereed)
    Abstract [en]

    We present an improved statistical model of the measurement process of triangulation Light Detection and Rangings (Lidars) that takes into account bias and variance effects coming from two different sources of uncertainty: (i) mechanical imperfections on the geometry and properties of their pinhole lens - CCD camera systems, and (ii) inaccuracies in the measurement of the angular displacement of the sensor due to non ideal measurements from the internal encoder of the sensor. This model extends thus the one presented in [2] by adding this second source of errors. Besides proposing the statistical model, this chapter considers: (i) specialized and dedicated model calibration algorithms that exploit Maximum Likelihood (ML)/Akaike Information Criterion (AIC) concepts and that use training datasets collected in a controlled setup, and (ii) tailored statistical strategies that use the calibration results to statistically process the raw sensor measurements in non controlled but structured environments where there is a high chance for the sensor to be detecting objects with flat surfaces (e.g., walls). These newly proposed algorithms are thus specially designed and optimized for inferring precisely the angular orientation of the Lidar sensor with respect to the detected object, a feature that is beneficial especially for indoor navigation purposes.

  • 55.
    Alhashimi, Anas
    et al.
    Luleå University of Technology, Luleå, Sweden.
    Varagnolo, Damiano
    Luleå University of Technology, Luleå, Sweden.
    Gustafsson, Thomas
    Luleå University of Technology, Luleå, Swede.
    Calibrating distance sensors for terrestrial applications without groundtruth information2017In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 17, no 12, p. 3698-3709Article in journal (Refereed)
    Abstract [en]

    This paper describes a new calibration procedure for distance sensors that does not require independent sources of groundtruth information, i.e., that is not based on comparing the measurements from the uncalibrated sensor against measurements from a precise device assumed as the groundtruth. Alternatively, the procedure assumes that the uncalibrated distance sensor moves in space on a straight line in an environment with fixed targets, so that the intrinsic parameters of the statistical model of the sensor readings are calibrated without requiring tests in controlled environments, but rather in environments where the sensor follows linear movement and objects do not move. The proposed calibration procedure exploits an approximated expectation maximization scheme on top of two ingredients: an heteroscedastic statistical model describing the measurement process, and a simplified dynamical model describing the linear sensor movement. The procedure is designed to be capable of not just estimating the parameters of one generic distance sensor, but rather integrating the most common sensors in robotic applications, such as Lidars, odometers, and sonar rangers and learn the intrinsic parameters of all these sensors simultaneously. Tests in a controlled environment led to a reduction of the mean squared error of the measurements returned by a commercial triangulation Lidar by a factor between 3 and 6, comparable to the efficiency of other state-of-the art groundtruth-based calibration procedures. Adding odometric and ultrasonic information further improved the performance index of the overall distance estimation strategy by a factor of up to 1.2. Tests also show high robustness against violating the linear movements assumption.

  • 56.
    Alhashimi, Anas
    et al.
    Luleå University of Technology, Luleå, Sweden.
    Varagnolo, Damiano
    Luleå University of Technology, Luleå, Sweden.
    Gustafsson, Thomas
    Luleå University of Technology, Luleå, Sweden.
    Joint Temperature-Lasing Mode Compensation for Time-of-Flight LiDAR Sensors2015In: Sensors, E-ISSN 1424-8220, Vol. 15, no 12, p. 31205-31223Article in journal (Refereed)
    Abstract [en]

    We propose an expectation maximization (EM) strategy for improving the precision of time of flight (ToF) light detection and ranging (LiDAR) scanners. The novel algorithm statistically accounts not only for the bias induced by temperature changes in the laser diode, but also for the multi-modality of the measurement noises that is induced by mode-hopping effects. Instrumental to the proposed EM algorithm, we also describe a general thermal dynamics model that can be learned either from just input-output data or from a combination of simple temperature experiments and information from the laser’s datasheet. We test the strategy on a SICK LMS 200 device and improve its average absolute error by a factor of three.

  • 57.
    Alhashimi, Anas
    et al.
    Luleå University of Technology, Luleå, Sweden.
    Varagnolo, Damiano
    Luleå University of Technology, Luleå, Sweden.
    Gustafsson, Thomas
    Luleå University of Technology, Luleå, Sweden.
    Statistical modeling and calibration of triangulation Lidars2016In: ICINCO 2016: Proceedings of the 13th International Conference on Informatics in Control, Automation and Robotics / [ed] Oleg Gusikhin; Dimitri Peaucelle; Kurosh Madani, SciTePress, 2016, Vol. 1, p. 308-317Conference paper (Refereed)
    Abstract [en]

    We aim at developing statistical tools that improve the accuracy and precision of the measurements returned by triangulation Light Detection and Rangings (Lidars). To this aim we: i) propose and validate a novel model that describes the statistics of the measurements of these Lidars, and that is built starting from mechanical considerations on the geometry and properties of their pinhole lens - CCD camera systems; ii) build, starting from this novel statistical model, a Maximum Likelihood (ML) / Akaike Information Criterion (AIC) -based sensor calibration algorithm that exploits training information collected in a controlled environment; iii) develop ML and Least Squares (LS) strategies that use the calibration results to statistically process the raw sensor measurements in non controlled environments. The overall technique allowed us to obtain empirical improvements of the normalized Mean Squared Error (MSE) from 0.0789 to 0.0046

  • 58.
    AL-Hindi, Rafah
    et al.
    Örebro University, School of Science and Technology.
    Yousef, Yousef
    Örebro University, School of Science and Technology.
    BIM Byggnadsinformationsmodellering BIM-användning hos de olika aktörerna2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Clarus Arkitekter as design companies often receive orders from contractors and clients asking for a BIM model. In most cases, the BIM model is not fully used, but 3D drawings or 2D drawings are available. Then asks the question "Does the client / contractor have the correct understanding of what BIM is?" Different players have different guidelines and requirements that the projector should follow, which can be perceived as defective by the projector just to know what is demanded from each client. The question the thesis will answer is "How should the consultant do the best to offer the right service and what goals the consultant will do.

    The purpose of this master thesis is to find out how BIM usage could facilitate the work as well as the communication between the various actors who is involved in a construction project. To investigate how the level of competence lies with the Client, Entrepreneur and Projectors / Architects and answerthe question "what is behind the skill difference that exists?".

    The work began with literature studies for the collection and compilation of information. Questions will be set up to later use them during interviews with different people from different companies. The interviews will take place with individuals from consultancy, contractor and client company.

    The interest in using BIM is high in the industry, but unfortunately there is a great deal of skills shortage. Customers and entrepreneurs plan to start using BIM more, which will happen in the coming years, but now, they do not want to take new risks and prefer to use traditional methods that are more secure. To be able to apply BIM more in the construction industry, more knowledge is needed.

    Download full text (pdf)
    fulltext
  • 59.
    Al-Hussein, Heba
    Örebro University, School of Science and Technology.
    PLATSBASERAD HANTERING AV SÄKERHETSRISKER PÅ EN BYGGARBETSPLATS PÅ SKANSKA2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Should there be a risk working at construction sites?

    This is an issue that is daily discussed by many construction companies. The Construction industry is a major industry that reflects and provides the society with what it needs in order to function, such as residences, hospitals, commercial buildings, roads, bridges, ports etcetera. In order to provide the society all these different types of constructions, there is a risk for those who work at the construction site. Accidents and occupational diseases are about twice as common among construction workers compared to the average worker according to Swedish Work Environment Authority [1].

    Skanska is one of the leading construction companies in Sweden, and is working hard with occupational health and safety issues. There is a vision of zero construction site accidents. "Mitt Gröna Kvarter" is an infill and rebuild project that has focused extra on safety. This extra focus on safety was the reason why this particular project was chosen to study health and safety, and to see how this can be improved more. How the safety should be handled and solved varies depending on the activity to be done and the risk that occurs at that specific location. Skanska has with SBUF support published two reports on how a building drawing can be used to increase the safety on construction sites, by collecting information using a reference group working in different projects.

    This academic work shows a new way to categorize safety risks on construction sites. The report shows how safety risks can be documented on the building drawings and regulations. The categorization method and the risk documentation in drawing and regulations can lower the safety risks in the constructions sites.

    A construction time plan contains all the activities that must be done before a building is completed, and all the safety risks can be linked to the timetable even if this is an ineffective method. In this academic work, studying the project "Mitt Gröna Kvarter", approximately 50% of all the security risks can be linked to a specific location. Therefore both an activity and location specific account of risks is an optimal solution.

  • 60.
    Ali Abokar, Abdirahman
    Örebro University, School of Science and Technology.
    Immersive Real-Time Multi-Projector Rendering2023Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This research project aims to advance the capabilities of real-time rendering in multiprojector setups by leveraging the power of the Unity game engine. The primary objective is to create a system that can seamlessly render a virtual environment in high-fidelity graphics in real-time to a multi-projector setup, providing users with an immersive visual experience. To achieve this, an efficient synchronization solution is implemented to distribute the rendering workload across two computers. The project addresses the challenges associated with multi-projector real-time rendering. Results indicate satisfactory frame rates and reliable performance, ensuring smooth visualization and interaction. Furthermore, future directions for exploration include enhancing interactivity, improving visual fidelity through advanced rendering techniques, optimizing scalability, and enabling multi-user collaboration. The potential impact of this research lies in pushing the boundaries of real-time multi-projector rendering and its applications in entertainment, education, architecture, and other domains.

  • 61.
    Ali Hussein, Maliun
    et al.
    Örebro University, School of Science and Technology.
    Marqus, Linda
    Örebro University, School of Science and Technology.
    EN MILJÖVÄNLIG OCH KOSTNADSEFFEKTIV AVFALLSHANTERING .- analys för utomhus avfallshantering.: AN ENVIRONMENTALLY FRIENDLY AND COST-EFFECTIVE WASTE MANAGEMENT - analysis for outdoor waste management.2022Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    On average, a person disposes of almost half a ton of waste per year. The more a country grows in population, the more its waste production grows. The largest proportion takes place in close proximity to the home and therefore alternative waste systems in a housing association have been examined and analyzed in this thesis. The purpose was to find a functioning waste system for older buildings where there is a lack of space for waste management. A case study was done at the tenant-owner association Haubitsen 2. The aim of the thesis was to find a new waste system for older buildings whose existing waste system consists of garbage dumps that end up in containers in the basement. Due to current rules regarding working environment and environmental requirements, such a waste system is no longer possible and a new solution is necessary. Through interviews, questionnaires and site visits, information contributed to the report has been obtained. Results of thesis show that vessel cabinets with separate vessels for residual waste and food waste, in connection with a street is a suitable solution. It meets future requirements for sorting food waste from residual waste and is at the same time cost-effective as there is only a one-off cost. The location is on a street where garbage trucks can drive in when collection takes place, which thus improves the work environment as the workload becomes less. 

  • 62.
    Ali Ibrahim, Yusuf
    Örebro University, School of Science and Technology.
    KOMMUNIKATION OCH INFORMATIONSFLÖDE En studie av förbättringsmöjligheter vid Strängbetongs fabrik i Kungsör: COMMUNICATION AND FLOW OF INFORMATION A study of the improvement opportunities at Strängbetong plant in Kungsör2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Effective communication and unobstructed flow of information is essential for an organization's productivity and efficiency. Previous research on communication and information flow shows that the efficiency and productivity of an organization is correlated with how well the communication and information flow works in the organization. The aim of the work presented in this report is to map and analyze the communication and information flow in Strängbetongs plant in Kungsör. Among the methods used during this work are interviews with staff from different departments and open talks with the production staff in the factory. In addition to interviews and conversations with the staff, how gathered information is used for production monitoring and productivity improvement has also been analyzed.

    How communication and information flow can be improved are presented in the conclusion. The result shows how inadequate communication between different partners whose work hangs together give rise to reduced productivity, increased waiting times and leads to rework and discard.

  • 63.
    Ali, Musa
    et al.
    Örebro University, School of Science and Technology.
    Cakmak, Alexander
    Örebro University, School of Science and Technology.
    TEST AV NYA GIVARE FÖR FUKTMÄTNING I BETONG- Mätutrustning kring relativ fuktutveckling i betong2019Independent thesis Basic level (degree of Bachelor of Fine Arts), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The drying of concrete continues to be a topic that doesn’t seem to have any good solutions, in particular the wayinfollowitupduringproductionandonsite.Concreteproducers,today,investalot of effort with concrete produced with a low water-cement ratio. This enables themtokeepthedrying times down and at the same time produce concrete with goodstrength.Thedryingtimeofconcreteis of importance as to when materials can be applied to concretewhichrelatestorelativehumidity,RH, within the concrete. The problem lays in the producers nothavingenoughknowledgeofgoodequipmentforfollowingthe relative humidity in the concrete. This has made the producers strengthen theirknowledgeinthearea by conducting their own tests with different measurement equipment that followstheRH.Thisreport is another example of that. The purpose of the report was corrected and adapted due to the time pressure that arose during the work. From having actually been looking for fully wireless and embedded sensors, it was made to perform tests with sensors without the need for wirelessness. Potential equipment was evaluated, tested and compared to present methods and equipments for following the RH in the concrete. The equipment that was used for the practical test were sensors, HYT 271 and HYT 221, developed by IST AG who specialises in the area. The results were then supposed to be compared to a present, RBK-sensor and method, to ensure the sensors reliability. The practical tests were executed in Kungsör and the measurement equipment were limited to electronic devices.Becauseofits’easyhandlingself-compactingconcretewasused.Thetestswiththe HYT 221 were not documented in this report due to the timeframe for the report. The sensor stopped working after approximately an hour and was temporarily stated not working, though it was later confirmed as working. After three (3) days when the sensor was removed and remounted, it was fully functional again. ​Thus, comparisons between the HYT sensor and the RBK-sensor could therefore not be completed accordingly to the purpose of the report. The conclusion is that the sensor is fully useable but didn’t satisfy the sought purpose which initself made the comparable RBK-tests irrelevant. In addition, the sensor needed to be removed and reactivated. The reason for that is believed to be the strenuous environment in the fresh concrete. Based on that conclusion the equipment is stated useless for the execution and inconvenient to use, therefore the product doesn´t acclimate for such execution. 

  • 64.
    Alijagic, A.
    et al.
    Örebro University, School of Science and Technology. Inflammatory Response and Infection Susceptibility Center (iRiSC).
    Scherbak, N.
    Örebro University, School of Science and Technology.
    Kotlyar, O.
    Örebro University, School of Science and Technology.
    Karlsson, P.
    Örebro University, School of Science and Technology. Department of Mechanical Engineering.
    Persson, A.
    Örebro University, School of Medical Sciences. Inflammatory Response and Infection Susceptibility Center (iRiSC).
    Hedbrant, A.
    Örebro University, School of Medical Sciences. Inflammatory Response and Infection Susceptibility Center (iRiSC).
    Norinder, U.
    Örebro University, School of Science and Technology.
    Larsson, M.
    Örebro University, School of Science and Technology.
    Felth, J.
    Uddeholms AB, Hagfors, Sweden.
    Andersson, L.
    Örebro University, School of Medical Sciences. Örebro University Hospital. Inflammatory Response and Infection Susceptibility Center (iRiSC); , Department of Occupational and Environmental Medicine.
    Särndahl, E.
    Örebro University, School of Medical Sciences. Inflammatory Response and Infection Susceptibility Center (iRiSC).
    Engwall, M.
    Örebro University, School of Science and Technology.
    Cell Painting unveils cell response signatures to (nano)particles formed in additive manufacturing2022In: Toxicology Letters, ISSN 0378-4274, E-ISSN 1879-3169, P17-01, Vol. 368, no Suppl. 1, p. S226-S227, article id P17-01Article in journal (Other academic)
  • 65.
    Alijagic, Andi
    et al.
    Örebro University, School of Science and Technology. School of Medical Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
    Engwall, Magnus
    Örebro University, School of Science and Technology.
    Särndahl, Eva
    Örebro University, School of Medical Sciences.
    Karlsson, Helen
    Department of Health, Medicine and Caring Sciences, Occupational and Environmental Medicine Center in Linköping, Linköping University, Linköping, Sweden.
    Hedbrant, Alexander
    Örebro University, School of Medical Sciences.
    Andersson, Lena
    Örebro University, School of Medical Sciences. Örebro University Hospital. Department of Occupational and Environmental Medicine.
    Karlsson, Patrik
    Örebro University, School of Science and Technology.
    Dalemo, Magnus
    Absolent AB, Lidköping, Sweden.
    Scherbak, Nikolai
    Örebro University, School of Science and Technology.
    Färnlund, Kim
    AMEXCI AB, Karlskoga, Sweden.
    Larsson, Maria
    Örebro University, School of Science and Technology.
    Persson, Alexander
    Örebro University, School of Medical Sciences.
    Particle Safety Assessment in Additive Manufacturing: From Exposure Risks to Advanced Toxicology Testing2022In: Frontiers in Toxicology, E-ISSN 2673-3080, Vol. 4, article id 836447Article, review/survey (Refereed)
    Abstract [en]

    Additive manufacturing (AM) or industrial three-dimensional (3D) printing drives a new spectrum of design and production possibilities; pushing the boundaries both in the application by production of sophisticated products as well as the development of next-generation materials. AM technologies apply a diversity of feedstocks, including plastic, metallic, and ceramic particle powders with distinct size, shape, and surface chemistry. In addition, powders are often reused, which may change the particles' physicochemical properties and by that alter their toxic potential. The AM production technology commonly relies on a laser or electron beam to selectively melt or sinter particle powders. Large energy input on feedstock powders generates several byproducts, including varying amounts of virgin microparticles, nanoparticles, spatter, and volatile chemicals that are emitted in the working environment; throughout the production and processing phases. The micro and nanoscale size may enable particles to interact with and to cross biological barriers, which could, in turn, give rise to unexpected adverse outcomes, including inflammation, oxidative stress, activation of signaling pathways, genotoxicity, and carcinogenicity. Another important aspect of AM-associated risks is emission/leakage of mono- and oligomers due to polymer breakdown and high temperature transformation of chemicals from polymeric particles, both during production, use, and in vivo, including in target cells. These chemicals are potential inducers of direct toxicity, genotoxicity, and endocrine disruption. Nevertheless, understanding whether AM particle powders and their byproducts may exert adverse effects in humans is largely lacking and urges comprehensive safety assessment across the entire AM lifecycle-spanning from virgin and reused to airborne particles. Therefore, this review will detail: 1) brief overview of the AM feedstock powders, impact of reuse on particle physicochemical properties, main exposure pathways and protective measures in AM industry, 2) role of particle biological identity and key toxicological endpoints in the particle safety assessment, and 3) next-generation toxicology approaches in nanosafety for safety assessment in AM. Altogether, the proposed testing approach will enable a deeper understanding of existing and emerging particle and chemical safety challenges and provide a strategy for the development of cutting-edge methodologies for hazard identification and risk assessment in the AM industry.

  • 66.
    Alirezaie, Marjan
    et al.
    Örebro University, School of Science and Technology.
    Kiselev, Andrey
    Örebro University, School of Science and Technology.
    Längkvist, Martin
    Örebro University, School of Science and Technology.
    Klügl, Franziska
    Örebro University, School of Science and Technology.
    Loutfi, Amy
    Örebro University, School of Science and Technology.
    An Ontology-Based Reasoning Framework for Querying Satellite Images for Disaster Monitoring2017In: Sensors, E-ISSN 1424-8220, Vol. 17, no 11, article id 2545Article in journal (Refereed)
    Abstract [en]

    This paper presents a framework in which satellite images are classified and augmented with additional semantic information to enable queries about what can be found on the map at a particular location, but also about paths that can be taken. This is achieved by a reasoning framework based on qualitative spatial reasoning that is able to find answers to high level queries that may vary on the current situation. This framework called SemCityMap, provides the full pipeline from enriching the raw image data with rudimentary labels to the integration of a knowledge representation and reasoning methods to user interfaces for high level querying. To illustrate the utility of SemCityMap in a disaster scenario, we use an urban environment—central Stockholm—in combination with a flood simulation. We show that the system provides useful answers to high-level queries also with respect to the current flood status. Examples of such queries concern path planning for vehicles or retrieval of safe regions such as “find all regions close to schools and far from the flooded area”. The particular advantage of our approach lies in the fact that ontological information and reasoning is explicitly integrated so that queries can be formulated in a natural way using concepts on appropriate level of abstraction, including additional constraints.

    Download full text (pdf)
    fulltext
  • 67.
    Alirezaie, Marjan
    et al.
    Örebro University, School of Science and Technology.
    Loutfi, Amy
    Örebro University, School of Science and Technology.
    Automated reasoning using abduction for interpretation of medical signals2014In: Journal of Biomedical Semantics, E-ISSN 2041-1480, Vol. 5, article id 35Article in journal (Refereed)
    Abstract [en]

    This paper proposes an approach to leverage upon existing ontologies in order to automate the annotation of time series medical data. The annotation is achieved by an abductive reasoner using parsimonious covering theorem in order to determine the best explanation or annotation for specific user defined events in the data. The novelty of this approach resides in part by the system’s flexibility in how events are defined by users and later detected by the system. This is achieved via the use of different ontologies which find relations between medical, lexical and numerical concepts. A second contribution resides in the application of an abductive reasoner which uses the online and existing ontologies to provide annotations. The proposed method is evaluated on datasets collected from ICU patients and the generated annotations are compared against those given by medical experts.

  • 68.
    Alirezaie, Marjan
    et al.
    Örebro University, School of Science and Technology.
    Loutfi, Amy
    Örebro University, School of Science and Technology.
    Ontology alignment for classification of low level sensor data2012Conference paper (Refereed)
  • 69.
    Alirezaie, Marjan
    et al.
    Örebro University, School of Science and Technology.
    Loutfi, Amy
    Örebro University, School of Science and Technology.
    Reasoning for Improved Sensor Data Interpretation in a Smart Home2014Conference paper (Refereed)
    Abstract [en]

    In this paper an ontological representation and reasoning paradigm has been proposed for interpretation of time-series signals. The signals come from sensors observing a smart environment. The signal chosen for the annotation process is a set of unintuitive and complexgas sensor data. The ontology of this paradigm is inspired form the SSNontology (Semantic Sensor Network) and used for representation of both the sensor data and the contextual information. The interpretation process is mainly done by an incremental ASP solver which as input receivesa logic program that is generated from the contents of the ontology. The contextual information together with high level domain knowledge given in the ontology are used to infer explanations (answer sets) for changes in the ambient air detected by the gas sensors.

  • 70.
    Alirezaie, Marjan
    et al.
    Örebro University, School of Science and Technology.
    Loutfi, Amy
    Örebro University, School of Science and Technology.
    Towards Automatic Ontology Alignment for Enriching Sensor Data Analysis2013In: Communications in Computer and Information Science, ISSN 1865-0929, E-ISSN 1865-0937, Vol. 415, p. 179-193Article in journal (Refereed)
    Abstract [en]

    In this work ontology alignment is used to align an ontology comprising high level knowledge to a structure representing the results of low-level sensor data classification. To resolve inherent uncertainties from the data driven classifier, an ontology about application domain is aligned to the classifier output and the result is recommendation system able to suggest a course of action that will resolve the uncertainty. This work is instantiated in a medical application domain where signals from an electronic nose are classified into different bacteria types. In case of misclassifications resulting from the data driven classifier, the alignment to an ontology representing traditional microbiology tests suggests a subset of tests most relevant to use. The result is a hybrid classification system (electronic nose and traditional testing) that automatically exploits domain knowledge in the identification process.

  • 71.
    Alirezaie, Marjan
    et al.
    Örebro University, School of Science and Technology.
    Pecora, Federico
    Örebro University, School of Science and Technology.
    Loutfi, Amy
    Örebro University, School of Science and Technology.
    Context Recognition: Towards Automatic Query Generation2015In: Ambient Intelligence: 12th European Conference, AmI 2015, Athens, Greece, November 11-13, 2015, Proceedings, Springer, 2015, p. 205-218Conference paper (Refereed)
    Abstract [en]

    In this paper, we present an ontology-based approach in designing knowledge model for context recognition (CR) systems. The main focus in this paper is on the use of an ontology to facilitate the generation of user-based queries to the CR system. By leveraging from the ontology, users need not know about sensor details and the structure of the ontology in expressing queries related to events of interest. To validate the approach and demonstrate the flexibility of the ontology for query generation, the ontology has been integrated in two separate application domains. The first domain considers a health care system implemented for the GiraffPlus project where the query generation process is automated to request information about activities of daily living. The second application uses the same ontology for an air quality monitoring application in the home. Since these two systems are independently developed for different purposes, the ease of applying the ontology upon them can be considered as a credit for its generality.

  • 72.
    Alirezaie, Marjan
    et al.
    Örebro University, School of Science and Technology.
    Renoux, Jennifer
    Örebro University, School of Science and Technology.
    Köckemann, Uwe
    Örebro University, School of Science and Technology.
    Kristoffersson, Annica
    Örebro University, School of Science and Technology.
    Karlsson, Lars
    Örebro University, School of Science and Technology.
    Blomqvist, Eva
    RISE SICS East, Linköping, Sweden.
    Tsiftes, Nicolas
    RISE SICS, Stockholm, Sweden.
    Voigt, Thiemo
    RISE SICS, Stockholm, Sweden.
    Loutfi, Amy
    Örebro University, School of Science and Technology.
    An Ontology-based Context-aware System for Smart Homes: E-care@home2017In: Sensors, E-ISSN 1424-8220, Vol. 17, no 7, article id 1586Article in journal (Refereed)
    Abstract [en]

    Smart home environments have a significant potential to provide for long-term monitoring of users with special needs in order to promote the possibility to age at home. Such environments are typically equipped with a number of heterogeneous sensors that monitor both health and environmental parameters. This paper presents a framework called E-care@home, consisting of an IoT infrastructure, which provides information with an unambiguous, shared meaning across IoT devices, end-users, relatives, health and care professionals and organizations. We focus on integrating measurements gathered from heterogeneous sources by using ontologies in order to enable semantic interpretation of events and context awareness. Activities are deduced using an incremental answer set solver for stream reasoning. The paper demonstrates the proposed framework using an instantiation of a smart environment that is able to perform context recognition based on the activities and the events occurring in the home.

    Download full text (pdf)
    fulltext
  • 73.
    Aljibouri, Ahmed
    et al.
    Örebro University, School of Science and Technology.
    Saeed, Rozha
    Örebro University, School of Science and Technology.
    Sociala krav och integration av nyanlända/utrikesfödda ingenjörer i byggsektorn2021Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sweden is one of the countries that contains multiculturalism. Several different ethnic groupsfrom different countries have settled in Sweden since the 1960s. Sweden has created severaldifferent organizations that have taken responsibility for being able to give the foreigner /immigrant the opportunity to enter the labor market in Sweden by validating their previousskills. Sweden's situation in the construction sector finds shortcomings in finding graduateengineers. This is one reason why Sweden has begun to accept foreign engineers with highskills and levels of education. Later, it has been realized that language in the constructionsector is important to be able to communicate, interact, respond to different situations anddifficulties and meet work requirements. According to the studies and the organizations, theydo not believe that engineers must use the Swedish language, but thus knowledge of theEnglish language should be available.During this investigation and study, they want to investigate and analyze various problemsthat may prevent newly arrived / foreign-born engineers from integrating into Sweden'sconstruction sector. From this, one wants to arrive at what language barriers one has toovercome in order to be able to get a permanent job. In addition to language and obstacles,they also want to investigate what opportunities there are for validation of their previouscompetencies that can fulfill qualifications and work roles in the construction sector inSweden. The survey has used interviews with NCC and Sweco organizations to make itsconclusions more credible. Both HR personnel specialists and trainees have participated in thesurvey by answering questions with themes that concern, validation, integration, workenvironment and communication.The survey study uses various literature books and other credible references to make ananalysis of the conclusions from the respondents' answers. The questionnaire survey aimed toinvestigate the current work situation for foreign engineers in Swedish society, the traineesdescribe their participation and experience in practice.One conclusion that the study comes to is that there are great opportunities to be able tovalidate previous competencies and get a permanent job as an engineer in the constructionsector. Arbetsförmedlingen works together with other construction organizations to establishand plan the recruitment of foreign engineers.

  • 74.
    Al-kutubi, Aje
    et al.
    Örebro University, School of Science and Technology.
    Yrlund, Josefin
    Örebro University, School of Science and Technology.
    INFRASTRUKTURKULVERT-En jämförelse av ekonomisk lönsamhet mellan infrastrukturkulvert och traditionellt ledningssystem.2020Independent thesis Basic level (degree of Bachelor of Fine Arts), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    When Vallastaden, a neighborhood in Linköping was to be constructed in 2017 they had a requirement to be able to make use of as much of the land as possible for construction. It was necessary to come up with an alternative way to construct the water and sewage system, so the development of infrastructure culverts started. They developed a complete system which lays in a protected environment and manages close contact to buildings. This sparked the interest of several municipalities, but it is still difficult to decide which method is the most feasible financially.By performing a theoretical simulation like an LCC-analysis the decisions can be made based on the data used. In order to perform this theoretical simulation literature study has been done in order to collect the data which has been used in Excel.The LCC-analysis has been limited to the knowledge based on the existing prerequisites. Based on these prerequisites the calculations have focused on the excavation-, plant- and maintenance costs.The results show that the breakeven point lays around 40 years, a clear difference can be seen between the financial feasibility of both systems. Infrastructure culverts are theoretically cheaper when the simulation is done with an interval of (+/-) 20% of the total price. Studies have also shown that infrastructure culverts have lower maintenance costs, which are the majority of the costs when it comes to this simulation. Maintenance costs are a yearly recurring cost which result in the system costs rising based on their maintenance.The conclusion is that infrastructure culverts are financially profitable based on the research done in the study. Infrastructure culverts have lower maintenance costs but could potentially have higher construction costs based on the project size.

    Download full text (pdf)
    fulltext
  • 75.
    Allbrand, Gustav
    et al.
    Örebro University, School of Science and Technology.
    Merry Land, Bahnan
    Örebro University, School of Science and Technology.
    EN UTVÄDERING AV FÖRSKOLORS INNEKLIMAT2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In Sweden, there are several municipalities in need of added facilities for preschool education. The responsible for the decisions in the municipalities use different ways to handle this problem. Some municipalities choose to use temporary facilities, such as barracks, others decide to build new permanent buildings. The manufacturers of the temporary barracks claim that there are no differences between temporary and permanent buildings in terms of thermal comfort and air quality. This report aims to clarify whether there is a difference in thermal comfort and air quality between temporary preschool facilities compared with new permanent preschools buildings. The three methods used when collecting information to this report were literature review, measurements and quantitative questionnaire. The report was limited to examine only thermal comfort and air quality. Noise and light or other aspect that affects thermal comfort and air quality were not taken into account in this investigation. The measurement of indoor air quality was limited to measuring carbon dioxide content and relative humidity. The thermal comfort was limited to measure of air temperature, mean radiant temperature, relative humidity and air velocity during a dag in the spring. The questionnaires were limited to be distributed only to pedagogues who work in the preschools where the measurements had been carried out. The results of the surveys clearly show that the experience of the thermal comfort and the air quality are poorer at the temporary preschool compared to permanent preschool. In the PMV and PPD indexes, the results of the carbon measurement and the measurement of relative humidity were approximately the same between the preschools. The report may indicate that the experience of the thermal comfort and air quality are more satisfying in the permanent compared with the temporary preschool. To validate our results further studies of measurements and empirical material are needed.

  • 76.
    Almerstedt, Matilda
    et al.
    Örebro University, School of Science and Technology.
    Lindhé, Johanna
    Örebro University, School of Science and Technology.
    Empirisk studie i form och geometrins upplevda inverkan på konsument produkter2012Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    It is unclear which mechanical properties that affect consumer products, it can be assumed that the shape and geometry affect the perceived feeling of consumer products. The aim of the project is to examine how the geometry and folding views affect the feeling in the use of consumer products.The study was performed on three consumer products of different dimensions where each product was produced in two different versions. The results showed that consumer product’s geometry is significant, while the folding views do not have a significant impact.

  • 77.
    Almestrand, Lovisa
    Örebro University, School of Science and Technology.
    Passivhus i Örebro län: Undersökning av marknaden för fastighetsägare2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This project aims to study the knowledge that property owners have of passive houses and if there is a market for this concept in Örebro County.

    Environmental and climate problems in the world are growing and a result of this is the constant circulating debate of passive houses. Low-energy houses are a necessary solution to reducing energy consumption, then the housing sector accounts for about 40 % of Sweden´s total energy use. Passive houses are a development of the low-energy house built without conventional heating systems and have a low energy use. Asplunds Bygg in Örebro is now building the very first passive houses in Örebro this spring 2009.

    The project began with contacting property owners to book interviews. The interviews were carried out over a four week period at the respective property owner's office. An independent in-depth were made parallel to the interviews by studying passivhus in literature, articles and on the Internet. The results of the interviews were compiled, compared and analyzed based on the purpose of the work.

    Property owners are receptive to the concept and believe that the energy issue is important, but that knowledge into passive houses of some is poor.  Finally found that from the results of the interviews it seems that there is a future market for passive houses in Örebro County. 

    Keywords: passive houses, low-energy houses, energy use, ventilation system, heat recovery, thick insulation.  

    Download full text (pdf)
    Passivhus i Örebro län
  • 78.
    Almér, Ida
    et al.
    Örebro University, School of Science and Technology.
    Hed, Johanna
    Örebro University, School of Science and Technology.
    Utveckling av delningsarm2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report describes a bachelor degree project conducted at the company EMBA Machinery AB. The company manufactures corrugated cardboard conversion machines. The machines convert cardboard sheets into folded corrugated boxes. EMBA´s machines are so-called internal machines that consist of several devices. The unit involved in the thesis work reported herein was the unit Counter Stacker. The Counter Stacker is the last unit in the EMBA machines, it counts and divides the finished cardboard boxes into bundles.

    EMBA wanted the authors to redesign the function that divides the sheets, the divider arm, in the affected unit. The divider arm should be controlled via electric servo operation and also act as a rebuild kit for previously sold machines.

    Calculations to investigate the stresses that arise at critical points in the design have been carried out. Motion profiles have been developed and motors and gearboxes have been dimensioned. Parallel to this a 3D-model was created in CAD. Based on the CAD-model, the company can proceed with creating complete drawing documents.

  • 79.
    Alnajar, Abdallah
    et al.
    Örebro University, School of Science and Technology.
    Jacobsson, Tobias
    Örebro University, School of Science and Technology.
    Produktutvecklingsprocess inom cirkulärekonomi2023Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report describes the execution of a bachelor's thesis. The work was conducted at the company WA3RM AB, whose business idea is to create value from unused resources in industries by connecting various stakeholders and achieving circular economy with the aim of reducing climate impact and achieving the global goals for sustainable development.

    WA3RM identified the need to map the work processes in product development projects, as the company intends to industrialize more products in the future. As part of WA3RM:s mapping of product development projects, the purpose of the thesis work was to create a process for concept selection in product development projects. The process was adapted to WA3RM:s needs, and the goal of the thesis work was to answer how a sustainability perspective can be established in the concept selection phase of product development projects.

    The thesis work was conducted using the Plan, Do, Check, Act method to structure and divide the work into sub-problems. Problem areas and limitations were defined and a mapping at the company was performed. A literature review was conducted based on the results of the mapping to identify tools and methods for the final proposal, the concept selection process.

    The mapping identified three main areas: requirements and goals, sustainability, and circular economy, which formed the basis for the literature review and the proposal, the concept selection process. The concept selection process consists of four phases, where applications are divided, ranked, generated to products, and finally ranked again. At the end of the process, the project team should have a basis for discussion to provide recommendations to the organization, regarding concept selection for further development in product development projects.

    A conclusion drawn from the thesis work was that the methods and tools in the process allows for consideration of sustainability aspects. However, it is important to consider other perspectives such as market and financing to develop feasible and competitive products, so that WA3RM can continue to industrialize products that reduce climate impact and inspire more stakeholders.

    Download full text (pdf)
    fulltext
  • 80.
    Al-Nazary, Naramsin
    et al.
    Örebro University, School of Science and Technology.
    Mirza, Daniel
    Örebro University, School of Science and Technology.
    Förbättringsarbeten i produktionsprocesser för att reducera kundreklamationer hos Volvo Construction Equipment AB.2021Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    At Volvo Construction Equipment in Hallsberg there are continuous improvements and projects to streamline the manufacture of their products. A problematic area in recent times has been a high proportion of customer complaints regarding cabs, the company therefore wants improvements in cab production. This report presents a case study on the causes and measures for customer complaints, based on existing documentation and interviews at the company, as well as new studies and mapping. Implementation of the study is divided into four main phases, Mapping of production, Review of customer complaints, Examination of root causes for quality deficiencies and Development of improvement proposals. The first two phases were performed to gain an understanding of the production of cabs and the customer complaints reported to the company. The manufacturing of cabs is carried out in three main production processes, welding, painting and assembly, where the assembly process is the most problematic regarding customer complaints and is thus the focus of the study. The cab assembly process has a main flow, ONE-LINE, where all cab models go through.The review of customer complaints resulted in the study being focused on four important fault types, damaged body, forgotten component, connection of contacts and screwing, which together accounted for 63% of all customer complaints in the cab assembly process. The investigation of root causes for customer complaints was done with the help of Ishikawa diagrams for each type of fault together with employees in the company's quality department and was also supplemented during discussions with operators on the cab assembly process. This resulted in the identification of the problem areas Unclear layout of materials (1), Unclear layout of tools (2), Distracting elements in the current working method (3), Not working according to a standardized working method (4) and Lack of fault protection for connecting contacts (5) in the cab assembly process. To fix the problems, the following improvement suggestions were made: Color-coded layout, Pick-To-Light System and Standardized screws (1), Tool list (2), Method after interruption and Rules for outsiders on ONE-LINE (3), Rotation and Digital instructions (4) and Color-coded connectors and Reduction of sound level on ONE-LINE (5). The company is recommended to continue the work by further investigating identified problem areas and the presented improvement proposals to implement measures to reduce customer complaints.

  • 81.
    Alp, Martin
    et al.
    Örebro University, School of Science and Technology.
    Dhiaa Muhsin, Mohammed
    Örebro University, School of Science and Technology.
    Livscykelanalys - En jämförelse mellan trähus och betonghus2020Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    When a raw material is being extracted to being used as a product and then demolished, environmental impact occurs in many different steps. With a Life-cycle-assessment (LCA), it is possible to calculate a product's environmental impact in all its phases. These are large amounts of greenhouse gases that are released into the environment and have a negative impact on the environment. The purpose of this report is to find out which of a wooden and concrete house is the most climate-smart in terms of emissions from extraction of materials until the house is completed.With the help of companies, we managed to obtain the quantity of the various houses in terms of material consumption for the foundation and walls of the houses. When the quantities have been obtained, the survey can go ahead and for this the tool Byggsektorns Miljöberäkningsverktyg is used where the quantities are calculated for the materials that are in demand.In order to achieve a result, certain parts of the life-cycle-assessment are delimited. Things that will be included in the report are the construction phase, i.e. A1-5 in the tool Byggsektorns Miljöberäkningsverktyg. This includes raw material extraction until the building is completed.The program calculations show that the concrete house accounts for a greater part of the climate impact than the wooden house. Concrete house's total climate impact (GWP), kg CO2 per m2 Atemp, is 48.753kg, while the wooden house's total climate impact is 14.836kg from the raw materials being extracted to the house being finished.The conclusion is that it is more climate smart and that there are more benefits to building a house in wood than building a house in concrete during the construction phase, even though they both have a concrete slab.

    Download full text (pdf)
    fulltext
  • 82.
    Alzghoul, Ahmad
    et al.
    Division of Computer Aided Design, Luleå University of Technology, Luleå, Sweden.
    Löfstrand, Magnus
    Division of Computer Aided Design, Luleå University of Technology, Luleå, Sweden.
    Increasing availability of industrial systems through data stream mining2011In: Computers & industrial engineering, ISSN 0360-8352, E-ISSN 1879-0550, Vol. 60, no 2, p. 195-205Article in journal (Refereed)
    Abstract [en]

    Improving industrial product reliability, maintainability and thus availability is a challenging task for many industrial companies. In industry, there is a growing need to process data in real time, since the generated data volume exceeds the available storage capacity. This paper consists of a review of data stream mining and data stream management systems aimed at improving product availability. Further, a newly developed and validated grid-based classifier method is presented and compared to one-class support vector machine (OCSVM) and a polygon-based classifier.

    The results showed that, using 10% of the total data set to train the algorithm, all three methods achieved good (>95% correct) overall classification accuracy. In addition, all three methods can be applied on both offline and online data.

    The speed of the resultant function from the OCSVM method was, not surprisingly, higher than the other two methods, but in industrial applications the OCSVMs' comparatively long time needed for training is a possible challenge. The main advantage of the grid-based classification method is that it allows for calculation of the probability (%) that a data point belongs to a specific class, and the method can be easily modified to be incremental.

    The high classification accuracy can be utilized to detect the failures at an early stage, thereby increasing the reliability and thus the availability of the product (since availability is a function of maintainability and reliability). In addition, the consequences of equipment failures in terms of time and cost can be mitigated.

  • 83.
    Alzghoul, Ahmad
    et al.
    Division of Computer Aided Design, Luleå University of Technology, Luleå, Sweden.
    Löfstrand, Magnus
    Division of Computer Aided Design, Luleå University of Technology, Luleå, Sweden.
    Backe, Björn
    Division of Computer Aided Design, Luleå University of Technology, Luleå, Sweden.
    Data stream forecasting for system fault prediction2012In: Computers & industrial engineering, ISSN 0360-8352, E-ISSN 1879-0550, Vol. 62, no 4, p. 972-978Article in journal (Refereed)
    Abstract [en]

    Competition among today’s industrial companies is very high. Therefore, system availability plays an important role and is a critical point for most companies. Detecting failures at an early stage or foreseeing them before they occur is crucial for machinery availability. Data analysis is the most common method for machine health condition monitoring. In this paper we propose a fault-detection system based on data stream prediction, data stream mining, and data stream management system (DSMS). Companies that are able to predict and avoid the occurrence of failures have an advantage over their competitors. The literature has shown that data prediction can also reduce the consumption of communication resources in distributed data stream processing. In this paper different data-stream-based linear regression prediction methods have been tested and compared within a newly developed fault detection system. Based on the fault detection system, three DSM algorithms outputs are compared to each other and to real data. The three applied and evaluated data stream mining algorithms were: Grid-based classifier, polygon-based method, and one-class support vector machines (OCSVM). The results showed that the linear regression method generally achieved good performance in predicting short-term data. (The best achieved performance was with a Mean Absolute Error (MAE) around 0.4, representing prediction accuracy of 87.5%). Not surprisingly, results showed that the classification accuracy was reduced when using the predicted data. However, the fault-detection system was able to attain an acceptable performance of around 89% classification accuracy when using predicted data.

  • 84.
    Alzghoul, Ahmad
    et al.
    Division of Computer Aided Design, Luleå University of Technology, Luleå, Sweden.
    Löfstrand, Magnus
    Division of Computer Aided Design, Luleå University of Technology, Luleå, Sweden.
    Karlsson, Lennart
    Division of Computer Aided Design, Luleå University of Technology, Luleå, Sweden.
    Karlberg, Magnus
    Division of Computer Aided Design, Luleå University of Technology, Luleå, Sweden.
    Data stream mining for increased functional product availability awareness2011In: Functional Thinking for Value Creation: Proceedings of the 3rd CIRP International Conference on Industrial Product Service Systems, Technische Universität Braunschweig, Braunschweig, Germany, May 5th - 6th, 2011 / [ed] Hesselbach, J. & Herrmann, C., Springer Berlin/Heidelberg, 2011, p. 237-241Conference paper (Refereed)
    Abstract [en]

    Functional Products (FP) and Product Service Systems (PSS) may be seen as integrated systems comprising hardware and support services. For such offerings, availability is key. Little research has been done on integrating Data Stream Management Systems (DSMS) for monitoring (parts of) a FP to improve system availability. This paper introduces an approach for how data stream mining may be applied to monitor hardware being part of a Functional Product. The result shows that DSMS have the potential to significantly support continuous availability awareness of industrial systems, especially important when the supplier is to supply a function with certain availability.

  • 85.
    Amato, Giuseppe
    et al.
    ISTI-CNR, Pisa, Italy.
    Broxvall, Mathias
    Örebro University, School of Science and Technology.
    Chessa, Stefano
    Università di Pisa, Pisa, Italy.
    Dragone, Mauro
    University College Dublin, Dublin, Ireland.
    Gennaro, Caludio
    ISTI-CNR, Pisa, Italy.
    Lopez, Rafa
    Robotnik Automation, Valencia, Spain.
    Maguire, Liam
    University of Ulster, Coleraine, Ireland.
    McGinnity, Martin T.
    University of Ulster, Coleraine, Ireland.
    Micheli, Alessio
    Università di Pisa, Pisa, Italy.
    Renteria, Arantxa
    Tecnalia, Derio, Spain.
    O’Hare, Gregory M. P.
    University College Dublin, Dublin, Ireland.
    Pecora, Federico
    Örebro University, School of Science and Technology.
    Robotic UBIquitous COgnitive Network2012In: Ambient Intelligence: Software and Applications / [ed] Paulo Novais, Kasper Hallenborg, Dante I. Tapia, Juan M. Corchado Rodríguez, Springer-Verlag New York, 2012, p. 191-195Conference paper (Refereed)
    Abstract [en]

    Robotic ecologies are networks of heterogeneous robotic devices pervasively embedded in everyday environments, where they cooperate to perform complex tasks. While their potential makes them increasingly popular, one fundamental problem is how to make them self-adaptive, so as to reduce the amount of preparation, pre-programming and human supervision that they require in real world applications. The EU FP7 project RUBICON develops self-sustaining learning solutions yielding cheaper, adaptive and efficient coordination of robotic ecologies. The approach we pursue builds upon a unique combination of methods from cognitive robotics, agent control systems, wireless sensor networks and machine learning. This paper briefly illustrates how these techniques are being extended, integrated, and applied to AAL applications.

  • 86.
    Amir, Halmat
    et al.
    Örebro University, School of Science and Technology. Örebro universitet.
    Björk, Chritian
    Örebro universitet.
    EGENKONTROLLER OCH FUKT, EN DEL I KVALITETSARBETET2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    To ensure a high quality of the final product it’s important that quality work is considered during the production. Quality work affects the company in a positive way by making our customers happy, improving and retaining our good reputation and leads to a good economy. NCC suspects that there’s insufficient quality work during production in the construction in-dustry across the country and based on that they want us to examine how they’re handling this. In this thesis we’ve done the interviews on five of NCC's ongoing projects in Örebro County in order to provide a picture about how the process of quality controls and moisture at the construction sites works. We’ll identify how employees work with their quality controls and moisture during the production, if there are any deficiencies in the work and in such case what’s causing it.

    Download full text (pdf)
    fulltext
  • 87.
    Amjad, Milad
    et al.
    Örebro University, School of Science and Technology.
    Hawash, Rammi
    Örebro University, School of Science and Technology.
    Identifiering av brister i interna flödet & kommunikation med hjälp av Lean2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today, many companies aim to implement Lean Production in their organizations through different approaches, methods and tools. The company where this project was carried out is active in the plastic film industry and are now aiming to work with the implementation of Lean. Amongst their products there are sealing tape, and ostomy pouches for the pharmaceutical industry. In this project, the sealing tape is the product which has been in focus. The company currently has problems such as bottlenecks within the production but also communication problems between departments and employees.

    The project was based on identifying deficiencies, wastes, and finding out the reasons why the communication is inadequate within the organization. This applies to the entire production process. With the help of tools within Lean and other improvements related to communication, a few deficiencies could be identified. A model was used for the basis of how the authors could move on to find the right tools to follow up and identify the problems. By following up on these problems, several improvement proposals have been presented to reduce and eliminate wastes that do not create value. Additional measures have been taken into action to continue to work on continuous improvements.

  • 88.
    Ammoura, Ramah
    et al.
    Örebro University, School of Science and Technology.
    Hussein Saleh, Ali
    Örebro University, School of Science and Technology.
    Bränder i höga trähus- att förebygga och åtgärda bränder i trästommar2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    More and more high-rise buildings are being built of wood, largely because of thedevelopment of factory-manufactured industrial building elements and building systems inrecent years. Despite great positive impact on the environmental impact of the constructionindustry, the fact remains that wood burns very easily, and spreads quickly unless the rightmeasures are taken at the design stage.The purpose of this study is to investigate how high wooden houses are protected againstfire during the design phase. The new function-based requirements from BBR opened upnew opportunities to build high in wood. The idea is to highlight and inform about therelatively new way of building high-rise buildings with the fire factor in focus.Interviews and literature studies formed the basis for this study of the effective methodsused in the design of tall wooden houses.The design is drastically affected if the frame is built of wood material. BBR, the FireBrigade and insurance companies are some of the experts consulted in connection withthis study. Information from Fire Engineers and Designers allowed us to see how fire isprevented and what changes are being made unlike houses of other materials.The literature study and interviews show that fire risks for these types of buildings areovercome after the implementation of all BBR regulations and laws with analytical designfor fire protection in Br0 buildings. Sensitive designs must be addressed through the use ofappropriate sealants around the throughings, secure fire cells with various disks such asplasterboard, non-combustible materials such as mineral wool can be used as insulatingmaterials, mechanical ventilation systems that can reduce fire spread through ventilationopenings, and automatic with manual fire extinguishers that can meet the requirements.The conclusion is that fire can definitely be prevented in the design of tall wooden housesby using the solutions we present in connection with this study.

    Download full text (pdf)
    fulltext
  • 89.
    Amouri, Alean
    et al.
    Örebro University, School of Science and Technology.
    Achhab, Rayan
    Örebro University, School of Science and Technology.
    Automatisering av packningsprocess hos Nobel Biocare AB2022Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nobel Biocare is an international medical technology company that manufactures dental implants which are used by licensed doctors for patients with dental problems who want to improve their oral health. The company is currently interested in Industry 4.0 and wants to upgrade into smart workshops through digitization and automation. This project's problem area is one of several areas that need improvement in Nobel, which in the long term can lead to Industry 4.0 and a smarter workshop. The packaging process in the company is today, to some extent, automated where an automatic machine is used for packaging implant articles (IP). In order for the products to be packed in the machine, it is required that an operator loads the articles one at a time onto a conveyor belt. This manual work activity that is performed by the operator today is repetitive, time consuming and laborious, which makes automation of interest. Thus, this thesis aims to generate and develop an efficient and practical solution for loading articles on the conveyor belt through automation or other solutions. The problem has been addressed by first mapping the current situation with the help of interviews, observations, document studies and time study to establish a value stream map. At the next step, requirements and desires were identified in a requirements specification and then solution proposals were generated with brainstorming and market research. Furthermore, external companies working with automation solutions were contacted to investigate whether the ideas developed are feasible. In connection with company contact, the result was developed and evaluated through an elimination matrix and a weighted criteria matrix. 

    Based on the weighted criteria matrix, it emerged that the best solution for the problem is a combination of a conveyor belt, magazine and two collaborative robots. Investing in the solution proposal means, among other things, a saving in manpower and time, which is presented in a value stream map of the future state. For further work, the solution should be studied further and tested before implementation. 

    Download full text (pdf)
    fulltext
  • 90.
    Amouzgar, Kaveh
    et al.
    Department of Mechanical Engineering, School of Engineering, Jönköping University, Jönköping, Sweden.
    Rashid, Asim
    Department of Mechanical Engineering, School of Engineering, Jönköping University, Jönköping, Sweden.
    Strömberg, Niclas
    Department of Mechanical Engineering, School of Engineering, Jönköping University, Jönköping, Sweden.
    Multi-objective optimization of a disc brake system by using SPEA2 and RBFN2013In: ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference: Volume 3B: 39th Design Automation Conference, New York: ASME Press, 2013Conference paper (Other academic)
    Abstract [en]

    Many engineering design optimization problems involve multiple conflicting objectives, which today often are obtained by computational expensive finite element simulations. Evolutionary multi-objective optimization (EMO) methods based on surrogate modeling is one approach of solving this class of problems. In this paper, multi-objective optimization of a disc brake system to a heavy truck by using EMO and radial basis function networks (RBFN) is presented. Three conflicting objectives are considered. These are: 1) minimizing the maximum temperature of the disc brake, 2) maximizing the brake energy of the system and 3) minimizing the mass of the back plate of the brake pad. An iterative Latin hypercube sampling method is used to construct the design of experiments (DoE) for the design variables. Next, thermo-mechanical finite element analysis of the disc brake, including frictional heating between the pad and the disc, is performed in order to determine the values of the first two objectives for the DoE. Surrogate models for the maximum temperature and the brake energy are created using RBFN with polynomial biases. Different radial basis functions are compared using statistical errors and cross validation errors (PRESS) to evaluate the accuracy of the surrogate models and to select the most accurate radial basis function. The multi-objective optimization problem is then solved by employing EMO using the strength Pareto evolutionary algorithm (SPEA2). Finally, the Pareto fronts generated by the proposed methodology are presented and discussed.

  • 91.
    Amouzgar, Kaveh
    et al.
    Department of Mechanical Engineering, School of Engineering, Jönköping University, Jönköping, Sweden .
    Strömberg, Niclas
    Department of Engineering Science, University West, Trollhättan, Sweden.
    An approach towards generating surrogate models by using RBFN with a priori bias2014In: Proceedings of the ASME International Design Engineering Technical Conferences & Computers and Information in Engineering Conference, 2014, Vol. 2B, New York, USA: ASME Press, 2014, article id V02BT03A024Conference paper (Refereed)
    Abstract [en]

    In this paper, an approach to generate surrogate modelsconstructed by radial basis function networks (RBFN) with a prioribias is presented. RBFN as a weighted combination of radialbasis functions only, might become singular and no interpolationis found. The standard approach to avoid this is to add a polynomialbias, where the bias is defined by imposing orthogonalityconditions between the weights of the radial basis functionsand the polynomial basis functions. Here, in the proposed a prioriapproach, the regression coefficients of the polynomial biasare simply calculated by using the normal equation without anyneed of the extra orthogonality prerequisite. In addition to thesimplicity of this approach, the method has also proven to predictthe actual functions more accurately compared to the RBFNwith a posteriori bias. Several test functions, including Rosenbrock,Branin-Hoo, Goldstein-Price functions and two mathematicalfunctions (one large scale), are used to evaluate the performanceof the proposed method by conducting a comparisonstudy and error analysis between the RBFN with a priori and aposteriori known biases. Furthermore, the aforementioned approachesare applied to an engineering design problem, that ismodeling of the material properties of a three phase sphericalgraphite iron (SGI) . The corresponding surrogate models arepresented and compared

    Download full text (pdf)
    fulltext
  • 92.
    Amouzgar, Kaveh
    et al.
    Product Development Department, School of Engineering, Jönköping University, Jönköping, Sweden; School of Engineering Science, University of Skövde, Skövde, Sweden.
    Strömberg, Niclas
    Örebro University, School of Science and Technology. Department of Mechanical Engineering.
    Radial Basis Functions as Surrogate Models with A Priori Bias in Comparison with a Posteriori Bias2017In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 55, no 4, p. 1453-1469Article in journal (Refereed)
    Abstract [en]

    In order to obtain a robust performance, the established approach when using radial basis function networks (RBF) as metamodels is to add a posteriori bias which is defined by extra orthogonality constraints. We mean that this is not needed, instead the bias can simply be set a priori by using the normal equation, i.e. the bias becomes the corresponding regression model. In this paper we demonstrate that the performance of our suggested approach with a priori bias is in general as good as, or even for many test examples better than, the performance of RBF with a posteriori bias. Using our approach, it is clear that the global response is modelled with the bias and that the details are captured with radial basis functions. The accuracy of the two approaches are investigated by using multiple test functions with different degrees of dimensionality. Furthermore, several modeling criteria, such as the type of radial basis functions used in the RBFs, dimension of the test functions, sampling techniques and size of samples, are considered to study their affect on the performance of the approaches. The power of RBF with a priori bias for surrogate based design optimization is also demonstrated by solving an established engineering benchmark of a welded beam and another benchmark for different sampling sets generated by successive screening, random, Latin hypercube and Hammersley sampling, respectively. The results obtained by evaluation of the performance metrics, the modeling criteria and the presented optimal solutions, demonstrate promising potentials of our RBF with a priori bias, in addition to the simplicity and straight-forward use of the approach.

  • 93.
    Ananiev, Anani
    et al.
    Örebro University, Department of Technology.
    Michelfelder, Thorsten
    Örebro University, Department of Technology.
    Kalaykov, Ivan
    Örebro University, Department of Technology.
    Driving redundant robots by a dedicated clutch-based actuator2007In: Robot motion and control 2007 / [ed] Krzysztof Kozłowski, Berlin: Springer , 2007, p. 167-176Conference paper (Other academic)
    Abstract [en]

    The redundancy in the body construction of humans and animals makes them very adaptable for a wide variety of natural environments. By switching/activating/deactivating they can accommodate the necessary locomotion for performing almost any task in their lifes. Therefore redundant and hyper-redundant robots are at the focus of research world-wide. The existing hyper-redundant robotic platforms are built in a plenty of mechanical constructions and purposes of use, but have a limited number of useful features that, unfortunately, limit their applicability in some important areas.

  • 94.
    Ander, Rebecka
    Örebro University, School of Science and Technology.
    Effektivisering av materialflödet genom processkartläggning2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    How does the current process look like and how can it be improved? That was the two questions that the company posed. That was the beginning for this degree project. Through process mapping and analysis of today's process, a proposal for development of the internal material flow has been made.

  • 95.
    Andersson, Alexander
    et al.
    Örebro University, School of Science and Technology.
    Hjelmqvist, Rasmus
    Örebro University, School of Science and Technology.
    Värdeflödeskartläggning och slöserier2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Atria Scandinavia is a company belonging to the Atria Group which is one of the largest companies in the food industry in Finland. One of their factories is located in Sköllersta, Sweden, that produce sausages, burgers and whole-meat products.

    Two products of whole-meat department was in need of a value stream mapping because the current time studies of the processes were no longer relevant. One of the products are one of the most common and oldest in Atria, sliced whole-muscle and the other a poultry product that is one of the newest. In order to calculate the cost of the sold goods in a correct manner an updated time-study was required.

    Value Stream Mapping is a powerful tool from the Lean philosophy that gives the company a very good overview of the value stream and all processes. This provides good opportunity for a deep understanding of the processes and value-flows, something that is vital for further improvement. The work with value stream analysis generated following results:

    • Updated time studies

    • Process descriptions

    • Value Stream Maps

    • Presentation of the value-adding as well as non-value-adding time

    • A kinship chart with problem areas in the value flows of the products

    • Possible root causes of problems in the flows

    • Proposed measures to handle these problems

    Download full text (pdf)
    fulltext
  • 96.
    Andersson, Birgitta
    et al.
    Örebro University, Department of Technology.
    Fast, Lars
    Holdstock, Paul
    Pirici, Diana
    Charging of a person exiting a car seat2009Conference paper (Refereed)
    Abstract [en]

    Electrostatic charge is generated by the contact, rubbing together and separation of clothing and car seat upholstery. It is also known that the charging levels will increase in a cold and dry climate. Charge on clothing will induce a separation of charge in the body of the wearer. The net result is an increase in the electrical potential of the body (or body voltage), thereby creating the risk of an electrostatic discharge (ESD) in the form of a spark from the charged human body to a large or earthed conductor. As charge is also bound to the surface of the clothing, brush discharges from the clothing can follow. The effects of sparks from the human body in the environment of a car may be a) to cause uncomfortable and distracting shocks to the person; b) to cause damage or disruption to electronic systems (GPS devices, vehicle management systems, etc); or c) to ignite flammable fuel vapour. A brush discharge from clothing may also ignite fuel vapour and be a risk for (unprotected) sensitive electronic devices (ESDS). The characteristic shape of the discharge current in a brush discharge is very similar to a Human Body Model (HBM) discharge. Measurement systems for determining body voltage and recording brush discharges are described. Results are presented of tests conducted with various combinations of car seat upholstery and clothing in different test environments. The antistatic property of some automotive textiles including conductive threads is emphasized.

  • 97.
    Andersson, Birgitta
    et al.
    Örebro University, Department of Technology.
    Stranneby, Dag
    Örebro University, Department of Technology.
    ESD – elektrostatiska urladdningar: risker och skydd vid elektronikhantering2002Book (Other (popular science, discussion, etc.))
  • 98.
    Andersson, Birgitta
    et al.
    Örebro University, School of Science and Technology.
    Stranneby, Dag
    Örebro University, School of Science and Technology.
    Long term charge retention on PWBs2005Conference paper (Other academic)
    Abstract [en]

    A sample of printed wiring boards, isolated from ground, has been charged tribo-electrically and the charge decay process has been studied with focus on the long-term charge decay behaviour. It was found that the time constant 1/e did not say much about the proceeding decay process. Instead a second-order approximation model for the measured decay curves has been suggested.

  • 99.
    Andersson, Birgitta
    et al.
    Örebro University, School of Science and Technology.
    Stranneby, Dag
    Örebro University, School of Science and Technology.
    Long term charge retention on PWBs2005Conference paper (Other academic)
    Abstract [en]

    A sample of printed wiring boards, isolated from ground, has been charged tribo-electrically and the charge decay process has been studied with focus on the long-term charge decay behaviour. It was found that the time constant 1/e did not say much about the proceeding decay process. Instead a second-order approximation model for the measured decay curves has been suggested.

  • 100.
    Andersson, Birgitta
    et al.
    Örebro University, Department of Technology.
    Stranneby, Dag
    Örebro University, Department of Technology.
    Long-term charge retention on PWBs2005In: Journal of Electrostatics, ISSN 0304-3886, E-ISSN 1873-5738, Vol. 63, no 6-10, p. 597-602Article in journal (Refereed)
    Abstract [en]

    A sample of printed wiring boards, isolated from ground, has been charged tribo-electrically and the charge decay process has been studied with focus on the long-term charge decay behaviour. It was found that the time constant 1/e did not say much about the proceeding decay process. Instead a second-order approximation model for the measured decay curves has been suggested.

1234567 51 - 100 of 2072
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf