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  • 51.
    Adamsson, Stina
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Kommunikationskanaler vid intern nyhetsspridning: En fallstudie om hur kommunikationskanaler påverkar den upplevda kommunikationseffektiviteten vid nyhetsspridning2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Communication is an important function within organizations and the ways of communicating have developed rapidly due to technological development, which can make it difficult to know which communication channel that is best to use in different situations. This report is based on a case study were the perceived communication efficiency tended to vary depending on which communication channel that was used. Previous research shows how the choice of communication channels can affect the communication efficiency, however, it does not show this from the perspective of news as an information type. Therefore, it was considered interesting to study how different communication channels affect the communication efficiency in terms of news distribution.

     

    The aim of this study was to illustrate and describe how communication channels affect the perceived communication efficiency when the information that is transferred consists of news. To achieve this, the following research question would be answered:

     

    • What advantages and disadvantages do employees experience with communication channels regarding the communication efficiency for news distribution in a large national company?

     

    Theories that have been applied in the study are Media Richness Theory and Osgood and Schramms circular communication model. Theories have been used to explain how news distribution takes place in the case company and to illustrate and possibly explain the problems that the company experience with news distribution.

     

    Data was collected by applying a qualitative method in which semi-structured interviews have been used. The result shows that respondents experience both advantages and disadvantages with all the communication channels and that the perceived communication efficiency tended to vary depending on which kind of news. When the result was set against the research question and the theoretical framework, advantages and disadvantages that were experienced, turned out to be depending on if the news were routine or non-routine and how it was matched with a rich or poor communication channel, which Media Richness Theory also declare. 

     

    The conclusion of this study shows that news distribution through face to face and telephone enables direct interaction and transmission of emotions, however, emotions are not transmitted as well through telephone as face to face. The many signals can also be experienced as overwhelmingly. E-mail, intranet and signboard are effective in terms of time and are not as depending on time and space. In addition, the possibility of direct interaction and transmission of feelings is limited. The result indicates that advantages and disadvantages with the communication channels seems to be linked to whether the channel is perceived as suitable to transfer different kinds of news. Rich communication channels are perceived to be effective for transmitting non-routine news and poor channels are perceived to be effective for transmitting routine news.

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  • 52.
    Adappan Ramu, Sasikala
    et al.
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Narasingam Kuppusamy, Venkatesh
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Exploring knowledge sharing in the Requirement Engineering phase of globally distributed Information Systems development: Perceived challenges and suggestions for improvement2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Master thesis explores the knowledge sharing that takes place during the requirement engineering phase of globally distributed information systems development. In recent years, due to globalization, information systems development activities have become increasingly distributed across different geographical locations. Requirement engineering is an important and knowledge intensive phase in the development of information systems. Requirement engineering is the process of identifying, analyzing, documenting, validating and managing the requirements of a system. Effective and efficient knowledge sharing during the requirement engineering is vital for the successful development of information systems. However, the global distribution of the stakeholders has affected knowledge sharing during requirement engineering in various ways making it more challenging.

     

    Drawing on the theories of knowledge sharing within the field of information systems, this interpretive research study aims at exploring stakeholders’ perceptions about the challenges met during the knowledge sharing in requirement engineering phase of globally distributed information systems development projects. More specifically, this Master thesis explores the perceived challenges and generates a list of suggestions to overcome the challenges by conducting qualitative semi-structured interviews among the key stakeholders, both customers and business analysts.

     

    The findings indicate that the knowledge sharing is influenced by challenges such as cultural differences, language barriers, communication issues, coordination issues arising from multiple stakeholders, time difference and difficulty in sharing tacit knowledge in the globally distributed settings. Participants’ suggestions for overcoming these challenges include cultural trainings, kick off meetings, language trainings, use of translator, face-to-face communication and interaction, video conferencing, scheduling important meetings in the common suitable timings, identification of the main stakeholders, having a mediator and making close observations with face-to-face interactions.

     

     

    Keywords:  Information Systems, Information Systems Development, Requirement Engineering, Knowledge Sharing, Global Distribution, Outsourcing

     

     

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    Master thesis in Informatics
  • 53.
    Addassi, Mouadh
    et al.
    Technical University of Denmark, Denmark.
    Johannesson, Björn
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Reactive mass transport in concrete including for gaseous constituents using a two-phase moisture transport approach2020In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 232, p. 1-14, article id 117148Article in journal (Refereed)
    Abstract [en]

    This article presents the further development of a tool for multi-phase reactive mass transport modelingfor durability estimation of cement-based materials, by the addition of the gas phase, adopting a trulyseparate two-phase moisture transport approach. The governing system of equations are based on phys-ically sound hybrid mixture based version of the Poisson-Nernst-Planck system of equations includinggaseous transport in the air-filled space, ionic transport in the liquid phase, electro-migration of ionicspecies, a two-phase moisture transport model, and sorption. The addition of the gas phase and thetwo-phase moisture description enables the user of the model to investigate individual and combinedeffects of different degradation processes in unsaturated systems. The altering of hydrated cement underthree different environments were studied representing an accelerated carbonation environment, a sub-merged marine environment and a cyclic drying-wetting zone in a marine environment, to illustratesome of the model’s capabilities.

  • 54.
    Addassi, Mouadh
    et al.
    Technical University of Denmark, Denmark.
    Johannesson, Björn
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Wadsö, Lars
    Lund University.
    Inverse analyses of effective diffusion parameters relevant for a two-phase moisture model of cementitious materials2018In: Cement and Concrete Research, ISSN 0008-8846, E-ISSN 1873-3948, Vol. 106, p. 117-129Article in journal (Refereed)
    Abstract [en]

    Here we present an inverse analyses approach to determining the two-phase moisture transport properties re-levant to concrete durability modeling. The purposed moisture transport model was based on a continuumapproach with two truly separate equations for the liquid and gas phase being connected by the sorption ki-netics. The moisture properties of ten binder-systems containingfly ash, calcined clay, burnt shale and graymicro-filler, were investigated experimentally. The experiments used were, (i) sorption test (moisturefixation),(ii) cup test in two different relative humidity intervals, (iii) drying test, and, (iv) capillary suction test. Masschange over time, as obtained from the drying test, the two different cup test intervals and the capillary suctiontest, was used to obtain the effective diffusion parameters using the proposed inverse analyses approach. Themoisture properties obtained with the proposed inverse analyses method provide a good description of the testperiod for the ten different binder-systems.

  • 55.
    Adetayo-odepidan, Mojeed
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Electronic Health Record Systems: A study of privacy in the region Kronoberg of Sweden2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study gives a brief description of paper-based record and the adoption of ICT, which brought the introduction of Electronic Health Record System (EHRS) in Sweden, the challenges facing EHR in the health care sector around the world and what immigrants and newcomers who just arrived in Sweden knows about the privacy,  rights and the policies that protect their privacy and data system, these could cause them not having enough confidence in electronic health record system, they could also be worried about their information been exposed or disclosed by their healthcare providers, this call for the confidentiality, security and privacy of EHR System. The aim of this study is to explore immigrants and newcomers as users of electronic health record system by setting interview questions and focus group to help the researcher to understand their knowledge of what they know about the privacy of EHRS and what they know about the policies health care providers follow to protect patient’s privacy and data. It is very important for them to know their rights and the rights that protect their privacy and data from been shared or disclosed.

     

    The study also talked about the existing implications facing EHRs, comparison of both systems was shown in table 1 of this study. The necessity for a proper protection of patient data was discussed and recommendation was made towards having a great and a working electronic health record system. 

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  • 56.
    Adolfsson, Beatrice
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Johansson Mess, Marja
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Driftoptimering av lakvatten­­rening: Jämförelse mellan tekniker för uppvärmning av nitrifikationsdammen på Häringetorp avfalls­anläggning2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Biologisk lakvattenrening, med hjälp av mikroorganismer, används på Häringetorp avfallsanläggning för att bland annat reducera mängden kväve i lakvattnet. För att möjliggöra en längre reningsperiod, eftersom mikro­organismernas tillväxt hämmas vid låga temperaturer, vill Tekniska förvaltningen på Växjö kommun studera möjligheten att värma upp nitrifikationsdammen på Häringetorp avfallsanläggning med hjälp av grön energi.

    Kvantifiering av effektbehov för förlängning av reningsperioden har gjorts utifrån en simuleringsmodell. Studie av tillförd effekt har gjorts under det första året med tillförd effekt. Jämförelse mellan de tekniska lösningarna solfångare, värmepump och biobränslepanna har gjorts gällande aspekterna driftsäkerhet, praktisk genomförbarhet, enkelhet och ekonomi. Utifrån diskussion ges rekommendation att installera en värmepump, vilken utnyttjar intern energi, för att levererar en effekt till nitrifikationsdammen på 100 kW under temperaturstyrda förhållanden. Denna tillförsel av effekt förväntas ge en förlängning av reningsperioden på fyra veckor.  

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  • 57.
    Adriansson, Mikael
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Johansson Breeze, Peter
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Kommunicera säkert: En studie om kommunikation mellan lotsar, befälhavare och bogserbåtsbefälhavare2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this study was to examine how pilots, vessel masters and tugboat masters perceive the importance of verbal communication with consideration to safety and efficiency.  This is based on the fact that the vast majority of accidents involving vessels occur because of human error, where lack of communication plays a large part. In the study semi-structured interviews were held with two pilots, two masters and two tugboat masters. After conducting these six interviews it became apparent at the use of standard phrasing and closed loop communication could vary. Based on the information collected one conclusion is that if the usage within these two areas improved safety could increase. It was also apparent in this study that the knowledge of the English language differed greatly which also could lead to misunderstandings with the giving of instructions. A better proficiency in English and better knowledge of verbal communication could be two possible ways of increasing safety.

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    Kommunicera säkert
  • 58.
    Aflaki, Kamyar
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Penetration And Security Testing As A Mean To Securing Universal Web Applications2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The domain of Information Technology has been discussed focusing the security of in-formation based on web application. The main purpose of the paper is to pinpoint andexplain the main attacks on web applications. In the study the I have used real world webapplication to demonstrate different types of attacks and the ways of prevention againstthem. Cyber criminals are using certain tactics to gather sensitive information throughweb applications, thus it is important to study this domain of IT. Experiment has beenconducted to demonstrate the concept and achieved outcomes have been explained. It hasbeen concluded that the most of the web application vulnerabilities come from a bad de-sign, according to Microsoft Developer Network (MSDN) Design Guidelines for SecureWeb Applications, and most of the threats can be prevented by considering basics of webapplication security while designing the application.

  • 59.
    Afridi, Muhammad Zeeshan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Umer, Muhammad
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Razi, Daniyal
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Design and simulation of beam steering for 1D and 2D phased antenna arrays using ADS.2012Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Phased arrays eliminate the problems of mechanical steering by using fast and reliable electronic components for steering the main beam. Modeling and simulation of beam steering for 1D and 2D arrays is the aspect that is considered in this thesis. A 1D array with 4 elements and a 2D array with 16 elements are studied in the X-band (8-12 GHz). The RF front-end of a phased array radar is modeled by means of ADS Momentum (Advanced design system).

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    Thesis Report
  • 60.
    Aggerstam, Elina
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Lehman, Karolina
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Materialvalets miljöpåverkan på transporten: En jämförelsestudie mellan transporter till flerfamiljshus i trä och betong.2017Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Under året 2015 bedömde 240 av Sveriges 290 kommuner att det existerade ett underslott på bostäder. För att kunna möta behovet krävs det att många bostäder ska byggas på en kort tid. Med de klimathot som världen står inför krävs det att produktionen är uthållig och hållbar i längden. För att nå klimatmålen måste användandet av tunga fordon minskas, logistiken måste effektiviseras och alternativa transportmedel bör undersökas.

    Syftet med studien var att identifiera eventuella skillnader mellan byggnadsmaterialen trä och betong i transportledet. Med den insamalade datan togs olika relations- och nyckeltal fram som sedan utgjorde basen för de två formlerna som presenteras i studien.

    Resultatet av de olika relationstalen indikerar på att den lastade vikten inte har stor betydelse på hur mycket CO2 som släpps ut, utan att det är antalet transporter med tung lastbil som är grundproblemet till utsläppen och miljöpåverkan. Med formlerna som presenteras i studien kan antalet transporter som krävs till ett flerfamiljshus räknas ut, men även mängden CO2 som släpps ut vid fraktandet av planelementen.

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    Materialvalets miljöpåverkan på transporten
  • 61.
    Ahlgren, Fredrik
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Reducing ships' fuel consumption and emissions by learning from data2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the context of reducing both greenhouse gases and hazardous emissions, the shipping sector faces a major challenge as it is currently responsible for 11% of the transport sector’s anthropogenic greenhouse gas emissions. Even as emissions reductions are needed, the demand for the transport sector rises exponentially every year. This thesis aims to investigate the potential to use ships’ existing internal energy systems more efficiently. The thesis focusses on making existing ships in real operating conditions more efficient based logged machinery data. This dissertation presents results that can make ship more energy efficient by utilising waste heat recovery and machine learning tools. A significant part of this thesis is based on data from a cruise ship in the Baltic Sea, and an extensive analysis of the ship’s internal energy system was made from over a year’s worth of data. The analysis included an exergy analysis, which also considers the usability of each energy flow. In three studies, the feasibility of using the waste heat from the engines was investigated, and the results indicate that significant measures can be undertaken with organic Rankine cycle devices. The organic Rankine cycle was simulated with data from the ship operations and optimised for off-design conditions, both regarding system design and organic fluid selection. The analysis demonstrates that there are considerable differences between the real operation of a ship and what it was initially designed for. In addition, a large two-stroke marine diesel was integrated into a simulation with an organic Rankine cycle, resulting in an energy efficiency improvement of 5%. This thesis also presents new methods of employing machine learning to predict energy consumption. Machine learning algorithms are readily available and free to use, and by using only a small subset of data points from the engines and existing fuel flow meters, the fuel consumption could be predicted with good accuracy. These results demonstrate a potential to improve operational efficiency without installing additional fuel meters. The thesis presents results concerning how data from ships can be used to further analyse and improve their efficiency, by using both add-on technologies for waste heat recovery and machine learning applications.

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    Doctoral Thesis (Comprehensive Summary)
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  • 62.
    Ahlgren, Fredrik
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Waste heat recovery in a cruise vessel2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In three studies of a cruise ship the author has investigated waste heat recovery (WHR)from exhaust gases using an organic Rankine cycle (ORC), and also mapped the energyand exergy flows within the ship. Data were collected from the ship’s machinerysystem for a total extent of one year, and this data were used for simulations andenergy calculations. An off-design analysis was made and an ORC was simulated andoptimised with regards to the ship’s operating conditions. The ORC working fluid wasoptimised in terms for maximum electrical production in the off-design condition. Theoff-design analysis showed that the ship speed and power consumption was far fromits original design. The results indicate that there is a potential for significant savingsby using an organic Rankine cycle for waste heat recovery. The energy and exergyanalysis gave a better understanding of the energy flows and showed that the singlelargest exergy destruction occurs in the ship’s diesel engines.

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  • 63.
    Ahlgren, Fredrik
    et al.
    University of Kalmar, Kalmar Maritime Academy.
    Ahlgren, Kristoffer
    University of Kalmar, Kalmar Maritime Academy.
    Gasens inverkan på oljan i ett hydrauliksystem2009Independent thesis Basic level (degree of Bachelor), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    I detta arbete har vi med en litteraturstudie försökt påvisa vad en inblandad gas i oljan i ett hydrauliksystem har för betydelse för funktionen. Vi har använt information i traditionell facklitteratur samt i tidskrifter och vetenskapliga rapporter och upptäckt att problemen som uppkommer av inblandade gaser inte är väl kända. Dagens lösningar på problemen är nästan alltid kostsamma och handlar om att behandla symptomen. Vi har tittat på de olika fysikaliska data som gasen inverkar på i oljan, utifrån detta har vi analyserat vilka effekter detta har för ett hydrauliksystems funktion. Vi kommer att diskutera grundproblemet till kavitation och vanliga problem som ett hydrauliksystem ofta har. Vi har lyckats presentera resultat på att inblandad gas i oljan har en mycket stor inverkan på ett hydrauliksystem. Vi har kommit fram till att mycket av dagens problem med hydrauliksystem helt skulle kunna byggas bort om man tog större hänsyn till oljans förmåga att lösa in luft.

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    FULLTEXT01
  • 64.
    Ahlgren, Fredrik
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Mondejar, Maria E.
    Lund University.
    Genrup, Magnus
    Lund University.
    Thern, Magnus
    Lund University.
    Waste Heat Recovery in a Cruise Vessel in the Baltic Sea by Using an Organic Rankine Cycle: A Case Study2015In: ASME Turbo Expo 2015: Turbine Technical Conference and Exposition: Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration, Montreal, Quebec, Canada, June 15–19, 2015, ASME Press, 2015, Vol. 3, p. 43392-43416, article id V003T06A018Conference paper (Refereed)
    Abstract [en]

    Maritime transportation is a significant contributor to SOx, NOx and particle matter emissions, even though it has a quite low CO2 impact. New regulations are being enforced in special areas that limit the amount of emissions from the ships. This fact, together with the high fuel prices, is driving the marine industry towards the improvement of the energy efficiency of current ship engines and the reduction of their energy demand. Although more sophisticated and complex engine designs can improve significantly the efficiency of the energy systems in ships, waste heat recovery arises as the most influent technique for the reduction of the energy consumption. In this sense, it is estimated that around 50% of the total energy from the fuel consumed in a ship is wasted and rejected in fluid and exhaust gas streams. The primary heat sources for waste heat recovery are the engine exhaust and the engine coolant. In this work, we present a study on the integration of an organic Rankine cycle (ORC) in an existing ship, for the recovery of the main and auxiliary engines exhaust heat. Experimental data from the operating conditions of the engines on the M/S Birka Stockholm cruise ship were logged during a port-to-port cruise from Stockholm to Mariehamn over a period of time close to one month. The ship has four main engines Wärtsilä 5850 kW for propulsion, and four auxiliary engines 2760 kW used for electrical consumers. A number of six load conditions were identified depending on the vessel speed. The speed range from 12–14 knots was considered as the design condition, as it was present during more than 34% of the time. In this study, the average values of the engines exhaust temperatures and mass flow rates, for each load case, were used as inputs for a model of an ORC. The main parameters of the ORC, including working fluid and turbine configuration, were optimized based on the criteria of maximum net power output and compactness of the installation components. Results from the study showed that an ORC with internal regeneration using benzene would yield the greatest average net power output over the operating time. For this situation, the power production of the ORC would represent about 22% of the total electricity consumption on board. These data confirmed the ORC as a feasible and promising technology for the reduction of fuel consumption and CO2 emissions of existing ships.

  • 65.
    Ahlgren, Fredrik
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Mondejar, Maria E.
    Lund University.
    Genrup, Magnus
    Lund University, Sweden.
    Thern, Marcus
    Lund University, Sweden.
    Waste Heat Recovery in a Cruise Vessel in the Baltic Sea by Using an Organic Rankine Cycle: A Case Study2016In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 1, article id 011702Article in journal (Refereed)
    Abstract [en]

    Maritime transportation is a significant contributor to SOx,NOx, and particle matter (PM) emissions, and to a lesser extent, of CO2. Recently, new regulations are being enforced in special geographical areas to limit the amount of emissions from the ships. This fact, together with the high fuel prices, is driving the marine industry toward the improvement of the energy efficiency of ships. Although more sophisticated and complex engine designs can improve significantly of the energy systems on ships, waste heat recovery arises as the most effective technique for the reduction of the energy consump- tion. In this sense, it is estimated that around 50% of the total energy from the fuel con- sumed in a ship is wasted and rejected through liquid and gas streams. The primary heat sources for waste heat recovery are the engine exhaust and coolant. In this work, we present a study on the integration of an organic Rankine cycle (ORC) in an existing ship, for the recovery of the main and auxiliary engines (AE) exhaust heat. Experimental data from the engines on the cruise ship M/S Birka Stockholm were logged during a port-to- port cruise from Stockholm to Mariehamn, over a period of 4 weeks. The ship has four main engines (ME) W€artsil€ a 5850kW for propulsion, and four AE 2760kW which areused for electrical generation. Six engine load conditions were identified depending on the ship’s speed. The speed range from 12 to 14 kn was considered as the design condi- tion for the ORC, as it was present during more than 34% of the time. In this study, the average values of the engines exhaust temperatures and mass flow rates, for each load case, were used as inputs for a model of an ORC. The main parameters of the ORC, including working fluid and turbine configuration, were optimized based on the criteria of maximum net power output and compactness of the installation components. Results from the study showed that an ORC with internal regeneration using benzene as working fluid would yield the greatest average net power output over the operating time. For this situation, the power production of the ORC would represent about 22% of the total elec- tricity consumption on board. These data confirmed the ORC as a feasible and promisingtechnology for the reduction of fuel consumption and CO2 emissions of existing ships.

  • 66.
    Ahlgren, Fredrik
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Mondejar, Maria E.
    Technical University of Denmark, Denmark.
    Thern, Marcus
    Lund University, Sweden.
    Predicting dynamic fuel oil consumption on ships with automated machine learning2019In: Innovative Solutions for Energy Transitions: Proceedings of the 10th International Conference on Applied Energy (ICAE2018) / [ed] Prof. J.Yanab, Prof. H.Yang, cDr. H.Lid, Dr. X.Chene, Elsevier, 2019, Vol. 158, p. 6126-6131Conference paper (Refereed)
    Abstract [en]

    This study demonstrates a method for predicting the dynamic fuel consumption on board ships using automated machine learning algorithms, fed only with data for larger time intervals from 12 hours up to 96 hours. The machine learning algorithm trained on dynamic data from shorter time intervals of the engine features together with longer time interval data for the fuel consumption. To give the operator and ship owner real-time energy efficiency statistics, it is essential to be able to predict the dynamic fuel oil consumption. The conventional approach to getting these data is by installing additional mass flow meters, but these come with added cost and complexity. In this study, we propose a machine learning approach using auto machine learning optimisation, with already available data from the machinery logging system.

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  • 67.
    Ahlgren, Fredrik
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Thern, Marcus
    Lunds Tekniska Högskola.
    Auto Machine Learning for predicting Ship Fuel Consumption2018In: Proceedings of ECOS 2018 - the 31st International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, Guimarães, 2018Conference paper (Refereed)
    Abstract [en]

    In recent years, machine learning has evolved in a fast pace as both algorithms and computing power are constantly improving. In this study, a machine learning model for predicting the fuel oil consumption from engine data has been developed for a cruise ship operating in the Baltic Sea. The cruise ship is equipped with legacy volume flow meters and newly installed mass flow meters, as well as an extensive set of logged time series data from the machinery logging system. The model is developed using state-of-the-art Auto Machine Learning tools, which optimises both the model hyper parameters and the model selection by using genetic algorithms. To further increase the model accuracy, a pipeline of different models and pre-processing algorithms is evaluated. An extensive model trained for a certain system can be used for optimisation simulation, as well as online energy efficiency prediction. As the models automatically adapt to noisy sensor data and thus function as a watermark of the machinery system, these algorithms show a potential in predicting ship energy efficiency without installation of additional mass flow meters. All tools used in this study are Open Source tools written in Python and can be applied on board. The study shows great potential for utilising large amounts of already available sensor data for improving the accuracy of the predicted ship energy consumption.

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  • 68.
    Ahlgren, Fredrik
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Thern, Marcus
    Lund University.
    Genrup, Magnus
    Lund University.
    Mondejar, Maria E.
    Technical University of Denmark, Denmark.
    Energy integration of organic rankine cycle, exhaust gas recirculation and scrubber2018In: Trends and challenges in maritime energy management / [ed] Aykut I. Ölçer, Momoko Kitada, Dimitrios Dalaklis & Fabio Ballini, Cham, Switzerland: Springer, 2018, p. 157-168Chapter in book (Refereed)
    Abstract [en]

    The vast majority of ships trafficking the oceans are fuelled by residual oil with high content of sulphur, which produces sulphur oxides (SOx) when combusted. Additionally, the high pressures and temperatures in modern diesel engines also produce nitrogen oxides (NOx). These emissions are both a hazard to health and the local environment, and regulations enforced by the International Maritime Organization (IMO) are driving the maritime sector towards the use of either distillate fuels containing less sulphur, or the use of exhaust gas cleaning devices.TwocommontechniquesforremovingSOx andlimitingNOx aretheopen loop wet scrubber and exhaust gas recirculation (EGR). A scrubber and EGR installation reduces the overall efficiency of the system as it needs significant pumping power, which means that the exhaust gases are cleaner but at the expense of higher CO2 emissions. In this paper we propose a method to integrate an exhaust gas cleaning device for both NOx and SOx with an organic Rankine cycle for waste heat recovery, thereby enhancing the system efficiency. We investigate three ORC configurations, integrated with the energy flows from both an existing state-of-the-art EGR system and an additional open loop wet scrubber.

  • 69.
    Ahlgren, Fredrik
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Österman, Cecilia
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    A social sustainability perspective on an environmental intervention to reduce ship emissions2015In: Creating Sustainable Work-environments: Proceedings of NES2015, Nordic Ergonomics Society 47th Annual Conference, 01-04 November 2015, Lillehammer, Norway / [ed] Knut Inge Fostervold, Svein Åge Kjøs Johnsen, Leif Rydstedt, Reidulf G. Watten, 2015, p. A4-12-A4-15Conference paper (Refereed)
    Abstract [en]

    This paper reports a case study examining the effects on the shipboard work environment of an operative decision to change fuel oil type on two Swedish passenger vessels operating in the Baltic Sea. The results show positive changes in work tasks, reduced exposure to harmful pollutants evaporating from the fuel, reduced use of chemicals for cleaning, and a generally cleaner work environment. The outcome illustrates the benefit of a systems perspective when evaluating environmental interventions. Here, the intervention can be seen as an investment that not only reduces emissions to the environment, but contributes towards sustainable working life at sea.

  • 70.
    Ahlgren, Sara
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Lindström, Jenny
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Ekonomi, kunskap och kommunikation: – Avgörande för den estetiska kvaliteten vid nyproduktion av bostäder2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There are indications that the architecture in Sweden is perceived as more and more monotonous with the absence of aesthetic qualities. Architects are allowed to bear responsibility for the claim but they themselves believe that they deprived their position in the construction process where they are replaced under ongoing projects, ancillary financial interests.

    The goal of the work was to find out what happens to a building's aesthetic qualities when the architect is replaced and what lies behind the replacement of the architect. A comparison of two objects was made, one in which the architect has been involved throughout the process and one where the architect has been replaced. The study was conducted through fact-finding from literature, observations and interviews.

    The result shows that the desire to build beautifully with aesthetic qualities is strongly linked to the client's level of ambition. However, the overall result shows that aesthetic values are subordinated to the economy of the construction-process. Furthermore, it has emerged during the work with this essay that there is a lack of knowledge and difficulties in communication between the actors in the construction industry, especially between architects and contractors. 

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  • 71.
    Ahlgren, Tobias
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Eliassi, Jalal
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Värmeförluster vid utvändigt placerade ventilationssystem2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    To be able to handle tomorrows need for limited energy consumption we need to reduce our use of energy. The building sector stands for around 40 % of all energy consumption in the society. The government has put up a goal to reduce the energy consumption in our buildings with 20 % by year 2020 and 50 % by year 2050 compared with year 1995. To be able to do reach that goal we need a more energy efficient building stock.

    The main part of the energy used in our buildings is used for space heating. By installing ventilation systems with heat recovery on the exhaust air it is possible to use the heat-energy in the exhaust air to warm up the incoming air. This can contribute to a reduction in energy use.

    A ventilation system with heat recovery on the exhaust air is space demanding and there can be problems with finding enough space to do the installation indoors. Therefore it can be an advantage to place the aggregate and the ducts on the outside of the buildings climate shell. A placement exterior of the buildings climate shell or in an unheated space leads to thermal heat losses.

    The aim with this essay is to investigate how significant the heat losses are on exterior placed ventilation systems. The investigation has been done with help of theoretical calculations and measurements of the temperature difference in the ventilation ducts. Analysis has been made on life cycle costs on how to reduce the heat losses in an economic manner. To buildings, Höstvägen 14 and 22 in Växjö, which have been equipped with exterior placed ventilation systems have been studied. The two buildings have two different types of installation of the ducts.

    Our result shows that the heat losses through the ventilation systems on Höstvägen 14 and 22 are significant. The majority of the losses occur in the ducts. In the aggregate the thermal bridges in the framework accounts for the larger part.

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  • 72.
    Ahlin, Jane
    et al.
    Swedish Ergonomics and Human Factors Society, Sweden.
    Österman, Cecilia
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Osvalder, Anna-Lisa
    Chalmers University of technology, Sweden.
    Hemphälä, Hilevi
    Lund University, Sweden.
    Glimne, Susanne
    Karolinska Insitutet, Sweden.
    Hägg, Göran M
    KTH Royal Institute of Technology, Sweden.
    Janzon, Olle
    SSAB Europe, Occupational Health & Safety.
    Pettersson, Per Johan
    Merident Optergo AB.
    Stavervik, Mathias
    Ericsson AB, Sweden.
    Strategies to develop and strengthen human factors and ergonomics knowledge among stakeholders in Sweden2015In: Proceedings 19th Triennial Congress of the IEA, Melbourne 9-14 August 2015, Melbourne: International Ergonomics Association , 2015Conference paper (Refereed)
    Abstract [en]

    Knowledge and application of human factors and ergonomics (HFE) has significant potential as auseful tool and solution provider in the development, design and implementation of safe, efficient and sustainable artefacts and systems. Yet, it seems that this HFE knowledge is not utilised to its full potential. In a world of competing financial and commercial priorities, HFE specialists have apparently not succeeded in selling the systems approach as a tool towards improved overall systems performance and human well-being.

    The present paper describes the strategic and practical workperformed by the Swedish Ergonomics and Human Factors Society (EHSS) to strengthen the quality of human factors and ergonomics knowledge and practice among various stakeholders in Sweden. EHSS view human factors and ergonomics as a systems and design oriented discipline that extends across all aspects of human activity. Beyond the traditional domains of specialization within the discipline, the physical, cognitive and organisational ergonomics, EHSS has identified three focus areas; visual ergonomics, voice ergonomics and ergonomics design for all.

    Practitioner Summary: This paper presents the strategic and practical work performed by the Swedish Ergonomics and Human Factors Society (EHSS) in order to strengthen the quality of human factors and ergonomics knowledge and practice in Sweden. EHSS has identified three focus areas for its strategic work: visual ergonomics, voice ergonomics and ergonomics design for all.

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    fulltext
  • 73.
    Ahlin, Kjell
    et al.
    Saven EduTech AB.
    Brandt, Anders
    Saven EduTech AB.
    A smart way to analyze dynamic data2003In: Sound & vibration, ISSN 1541-0161, no February, p. 20-22Article in journal (Other academic)
    Abstract [en]

    In recent years MATLAB® has become a common software tool for general computational mathematics, in universities as well as in industry. In the field of noise and vibration analysis, MATLAB is very common in universities, but perhaps a little less common in the industrial world. In this article some ideas are presented on how MATLAB can be successfully used for analyzing experimental noise and vibration data. Through the introduction of toolboxes in this field, the less experienced user can take advantage of the powerful functionality of MATLAB, either as the main tool or as a complement to the many excellent menu driven systems available on the market. Some of the advantages and disadvantages of using MATLAB versus menu driven systems are also discussed.

  • 74.
    Ahlin, Kjell
    et al.
    Blekinge Institute of Technology.
    Brandt, Anders
    Axiom EduTech AB.
    Lagö, Thomas
    A New MATLAB Toolbox for Simulation and Parameter Identification of Nonlinear Mechanical Systems2007In: IMAC-XXV: A Conference & Exposition on Structural Dynamics, February 19 – 22, 2007, Orlando, Florida USA, 2007Conference paper (Refereed)
  • 75.
    Ahlin, Klara
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Identifiering och visualisering av aktuella ämnen och sociala relationer i ett mikrobloggnätverk.: Riksdagspartiernas twitteranvändning inför riksdagsvalet 20102010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Att enskilda politiker och partier väljer att använda sig av sociala medier i valsammanhang blir allt vanligare. I denna uppsats granskades de svenska riksdagspartiernas twitteranvändning inför det svenska riksdagsvalet 2010. Genom en social- och innehållsmässig analys kring twitteranvändandet kunde enskilda partiers kommunikationsmönster anas. Den sociala analysen baserades på relationen mellan en användares följare och följande, den innehållsmässiga på de taggar nätverkets mikroblogginlägg märkts med.

    Bland annat identifierades två partier med en ren tvåvägskommunikation, och ett parti med en klar envägskommunikation. Två av de undersökta partierna hade även tendenser till att rikta sin kommunikation mot en inre grupp av politiska twittrare. Den innehållsmässiga analysen pekade även på att de olika partiernas nätverk till viss del har en liknande sammansättning, politikerna hade en tendens att följa varandra och partispecifika taggar dök upp i samtliga av de analyserade partiernas nätverk. Datan använd i analysen hämtades med hjälp av en utvecklad prototyp.

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  • 76.
    Ahlin, Kristofer
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Absorptionskylmaskiner ombord: En undersökning om absorptionsprocessens potential ombord fartyg2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Målet med denna undersökning är att teoretiskt undersöka den vatten/litiumbromidbaserade absorptionsprocessens potential ombord fartyg då processen enbart drivs av huvudmaskinens högtemperaturkylvatten. Undersökningen genomförs teoretiskt mot tre olika fartyg samt Sjöfartshögskolan i Kalmars maskinrumssimulator. För vardera fartyg undersöks driftenergikällan och kylbehovet ombord. Med det som underlag dras en slutsats om den vatten/ litiumbromidbaserade absorptionsprocessens potential ombord fartyget. Fartygens resultat ligger till grund för slutsatsen. Undersökningen visade att det finns potential för tekniken ombord undersökta fartyg.

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  • 77.
    Ahlqvist, Carl
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Meijer, Niklas
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Identifiering av faktorer som kan påverka produktionseffektivitet: En fallstudie2015Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Manufacturing industries are today facing increasing competition through the globalization of the market that takes place. A global market with several competitors, increased product differentiation and the high cost of production makes great demands on companies to work cost effectively. To be competitive and operate a profitable production requires companies to have a great knowledge of how their manufacturing processes work, has a high reliability and can use their facility's capacity.

     

    The basis for the study is the industrial profitability problems in Sweden, where companies find it increasingly difficult to produce quality products at a competitive price. The case study performed in a company which manufactures components for the automotive industry, with the aim to create a better understanding of the factors that lead to production disruptions and has great effect on the production efficiency of a flow. In order to be able to counter them and exploit the capacity of a better way and create a high level of competitiveness and profitability.

     

    Based on the analytical study and first described the present situation of the case now. This is followed by an analysis of the current situation where empiricism is compared with the relevant theory. The analysis then reports the measured values ​​of the factors that lead to disturbances in the production flow and affect production efficiency. Finally, the evaluation factors and an explanation of what they are due to be clarified. It results that the case study demonstrates the significant factors affecting production efficiency, as well as the underlying causes of these should be tackled in order to create a higher level of reliability and production efficiency in the flow. Examination of factors and causes creates a basis for the improvements that should be applied to maintain profitable production and competitiveness.

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  • 78.
    Ahlstedt, Sebastian
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Granath Karlsson, David
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Diskkrypteringsprestanda i GNU/Linux2013Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    This thesis compares the impact on disk performance in a GNU/Linux  environmentwith three encryption algorithms: AES,  Serpent and Twofish in three different implementations: DM-crypt, Loop-AES and Truecrypt. For all three algorithms a key length of 256 bits is used.

    The thesis shows that the least performance impact during data encryption, and thus file writing, is reached by using AES or Twofish encryption implemented in DM-crypt or TrueCrypt. The thesis shows that some data operations with a sufficiently low processor utilization barely affects disk performance at all if encrypted using the optimal implementation and algorithm.

    It is also discovered that the performance impact during data decryption, or file reading, can be minimized by using the most efficient implementation and algorithm. The best results are met with the AES or Twofish cipher, regardless of implementation.

    An important conclusion that  is  drawn is that it is hard to determine a superior encryption solution for all purposes. However, by reviewing and examining the collected data from all aspects of disk performance the AES implementation in TrueCrypt is, with small marginals, determined to be the most optimal.

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    Diskkrypteringsprestanda i GNU/Linux
  • 79.
    Ahlstrand, Johanna
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Bergman, Helena
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Energiblalands vid ny PO-reaktor: Vid Södra Cell Mönsterås2014Independent thesis Basic level (professional degree), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [sv]

    Vid Södra Cells fabrik i Mönsterås har ett beslut tagits att en ny PO-reaktor skulle installeras för att förlänga reaktionstiden och därmed sänka temperatur och kemikaliesats vilket resulterar i en högre dragstyrka för massan. En temperatursänkning medför mindre flashad ånga till PO-kondensorn vilket i sin tur medför mindre värme till sekundärvärmesystemet (sågslingan).

    Syftet var att verifiera attde beräkningar som anslaget bygger på är korrekta samt föreslå eventuella förändringar. Och ta reda på hur den nya PO-reaktorn kommer att påverka energibalansen i sekundärvärmesystemet. Konrollberäkningar har utförts samt ett försök för att se hur minskad flashånga påverkar sekundärvärmesystemet. Beräkningarna stämde förutsatt att temperatursänkningen blir 4°. Sekundärvärmesystemet kommer att påverkas av temperatursänkningen, och behöver därmed kompenseras.

  • 80.
    Ahmad, Aftab
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Performance of MLSE over Fading Channels2013Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    This work examines the performance of a wireless transceiver system. The environment is indoor channelsimulated by Rayleigh and Rician fading channels. The modulation scheme implemented is GMSK inthe transmitter. In the receiver the Viterbi MLSE is implemented to cancel noise and interference dueto the ltering and the channel. The BER against the SNR is analyzed in this thesis. The waterfallcurves are compared for two data rates of 1 M bps and 2 Mbps over both the Rayleigh and Rician fadingchannels.

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    Thesis
  • 81.
    Ahmad, Elaf
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Hultgren, Mathilda
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Möjligheter för visualisering i presentation av småhus2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Rapporten behandlar hur husleverantörer kan utveckla presentationsmaterial. De materialen som visas är olika husmodeller från företagen och behandlar bakgrundsvyer samt förbättringar i digital media. Företaget som ligger till grund för rapporten är Trivselhus, och undersökningarna i rapporten är baserade på aktörer i anknytning till företaget. Resultatet kan även tillämpas hos andra husleverantörer.

    Visualisering handlar om hur människan tar till sig den informationen som ges. Den används för att underlätta förståelsen för komplicerade bilder och idéer som visas för kunder. Visualisering möjliggör att bearbetade bilder kan kopplas samman med slutresultatet som presenteras.

    Informationen som kommer genom visualisering kan fås genom människans fem sinnen syn, lukt, hörsel, smak och känsel. Denna studie lägger fokus på den synliga aspekten till visualisering och hur företag kan använda den för att förstärka sin kundkrets.

    Resultatet ger exempel på visualisering som husleverantörer kan tillämpa i verksamheten. Det behandlar bland annat utveckling av hemsidor och gemensamma plattformar som kund och säljare båda kan arbeta i. Andra framtidsförslag som presenteras är en utveckling av visningshus samt producering av miniatyrhus. Detta för att ge kunden en bättre visualisering och därmed en större insyn i hur det färdiga huset är utformat och kommer fungera i verkligheten.

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  • 82.
    Ahmad, Muhammad
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Jhanzeb, Jhanzeb
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Modeling and Simulation of an Electrostatic Precipitator Including a Comsol Multiphysics Guide for Modeling an ESP2011Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Gaseous exhaust of different industries contains dust particles of different chemical precipitates that are harmful for the environment. Electrostatic Precipitators are very often used in industries to filter their gaseous exhaust and to prevent the atmosphere to being polluted. Electrostatic Precipitators are very efficient in their work. Electrostatic Precipitators use the force of the electric field to separate the dust particles from gaseous exhaust. Electrostatic Precipitators charge the dust particles and remove these particles by attracting these charged dust particles toward the collecting plates. The charging of dust particles requires a charging zone. When gas passes through that charging zone, the dust particles in the gas stream become charged and then these charged particles are attracted toward the collecting plates. The design of an Electrostatic Precipitators requires the knowledge of its working principle and the problems that often arise during its working. This thesis is the study of the working and the problems of the Electrostatic Precipitators. The main reason for problems in working of an Electrostatic Precipitator is the dust resistivity. This dust resistivity affects the collection performance of an Electrostatic Precipitator. This thesis also contains the simulation of an Electrostatic Precipitator. In the simulation part, the Electric Potential and the Electric Field of an ESP is modeled in an ideal condition, when no gas is flowing through the ESP. The industrial software Comsol Multiphysics is used for the simulation. A Comsol Multiphysics guide is given in appendix of this thesis report that provides information about using this software.

     

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  • 83.
    AHMAD, SHOAIB
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Finite Precision Error in FPGA Measurement2015Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Finite precision error in digital signal processing creates a threshold of quality of the processed signal. It is very important to agree on the outcome while paying in terms of power and performance.

    This project deals with the design and implementation of digital filters FIR and IIR, which is further utilized by a measurement system in order to correctly measure different parameters. Compared to analog filters, these digital filters have more precise and accurate results along with the flexibility of expected hardware and environmental changes. The error is exposed and the filters are implemented to meet the requirements of a measurement system using finite precision arithmetic and the results are also verified through MATLAB. Moreover with the help of simulations, a comparison between FIR and IIR digital filters have been presented.

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    Thesis Project
  • 84.
    Ahmad, Tanvir
    et al.
    Linnaeus University, Faculty of Engineering and Technology, Department of Computer Science.
    Haider, Muhammad Ashfaq
    Linnaeus University, Faculty of Engineering and Technology, Department of Computer Science.
    A Systematic Literature Review on Claims and supporting Evidence for Self-Adaptive Systems2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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    ThesisFullText
  • 85.
    Ahmad, Waqar
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Sultan Qaboos Univ, Oman.
    Vakilinejad, Ali
    Sultan Qaboos Univ, Oman;Univ Tehran, Iran.
    Aman, Zachary M.
    Univ Western Australia, Australia.
    Vakili-Nezhaad, G. Reza
    Sultan Qaboos Univ, Oman.
    Thermophysical Study of Binary Systems of tert-Amyl Methyl Ether with n-Hexane and m-Xylene2019In: Journal of Chemical and Engineering Data, ISSN 0021-9568, E-ISSN 1520-5134, Vol. 64, no 2, p. 459-470Article in journal (Refereed)
    Abstract [en]

    This work presents the experimentally determined density (rho), viscosity (eta), speed of sound (u), and surface tension (sigma) data for tert-amyl methyl ether (TAME) + n-hexane and TAME + m-xylene systems at several temperatures (298.15, 308.15, 318.15, 323.15, and 328.15 K). These experimentally determined thermophysical data are utilized to compute various excess/deviation parameters such as molar volume (V-E), isentropic compressibility (K-s(E)), speed of sound (u(E)), deviation in viscosity (Delta In eta), isobaric thermal expansion coefficient (alpha(E)(P)), and surface tension (sigma(E)). The inspection of parameters response may interpret the existing specific molecular interactions as well as the mixing behavior of solutions. The critical analysis of observed parametric behavior have unveiled the strong and weak molecular interactions in TAME with m-xylene and TAME with n-hexane systems, respectively.

  • 86.
    Ahmed, Abdirahman
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Undersökning av en högspänningsomvandlare: Parameteridentifiering, modellering och simulering av högfrekvent kraftomvandlare2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Analyzing parasitic elements of devices is important because they cause power losses. Minimizing the losses leads to less raw material consumption for devices, which in turn leads to reduced environmental impact. In the project a pulse generator is constructed which can provide low voltages pulses. Using the pulse generator, the parasitic components of the power converter with it’s transformer are identified and analyzed. After the parasitic analysis, a model for the transducer was developed. The system's U-I characteristics were simulated and analyzed at different switching pulse widths. In order to validate the results of the survey, the project has compared the physical measurements with simulation. The result shows good consistency.

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    Undersökning av en högspänningsomvandlare
  • 87.
    Ahmed, Abdirauf
    Linnaeus University, Faculty of Technology, Department of Mathematics. Migrationsverket.
    Describing and modelling the flow of the migration process with simple queueing systems.2018Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
    Abstract [en]

     The aim of this thesis is to apply M/M/1 and M/M/2 queueing system models

    to student and working visas applicants. From empirically observed arrival times and

    departure times, the arrival and service intensities are estimated. It is obtained that

    the estimated service intensities are essentially double for the M/M/1 queueing model

    compared to the M/M/2 model. Hence, the estimated trac intensities, as they are

    dened in this thesis, are almost the same here, and close to one. Furthermore, the

    empirical distribution of the time in the system for the student visas seems to be

    surprisingly well approximated by the theoretical ones obtained from the M/M/1 and

    M/M/2 models.

    The total time in the system for the two models are almost the same, while for

    the M/M/2 model the service times are about the double of the service times of the

    M/M/1 model which is compensated by shorter waiting times for the M/M/2 queue.

    Therefore, there is a struggle in modelling between having a quicker service time with

    less servers or a shorter waiting time period with more servers.

    Modelling of the total time in the system, which is the important time for the

    applicant and is as well the observed one, seems to be indierent to whether it is

    M/M/1 modelling or M/M/2 modelling. That indierence is explained by the fact

    that the estimated trac intensity is close to one.

    A major consideration is that there is a \wall" eect of the data. The \wall" eect

    arises from the ratio of the uncompleted and completed changes towards the end of

    year 2017. In this thesis the \wall" eect is resolved by removing the last data.

    2

  • 88.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Hansson, Lars
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Distribution of preservatives in thermally modified Scots pine and Norway spruce sapwood2013In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 47, no 3, p. 499-513Article in journal (Refereed)
    Abstract [en]

    Studying the impregnation and distribution of oil-based preservative in dried wood is complicated as wood is a nonhomogeneous, hygroscopic and porous material, and especially of anisotropic nature. However, this study is important since it has influence on the durability of wood. To enhance the durability of thermally modified wood, a new method for preservative impregnation is introduced, avoiding the need for external pressure or vacuum. This article presents a study on preservative distribution in thermally treated Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) sapwood using computed tomography scanning, light microscopy, and scanning electron microscopy. Secondary treatment of thermally modified wood was performed on a laboratory scale by impregnation with two types of preservatives, viz. Elit Träskydd (Beckers) and pine tar (tar), to evaluate their distribution in the wood cells. Preservative solutions were impregnated in the wood using a simple and effective method. Samples were preheated to 170 °C in a drying oven and immediately submerged in preservative solutions for simultaneous impregnation and cooling. Tar penetration was found higher than Beckers, and their distribution decreased with increasing sample length. Owing to some anatomical properties, uptake of preservatives was low in spruce. Besides, dry-induced interstitial spaces, which are proven important flow paths for seasoned wood, were not observed in this species.

  • 89.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology, Sweden.
    Morén, Tom
    Luleå University of Technology, Sweden.
    Moisture properties of heat-treated Scots pine and Norway spruce sapwood impregnated with wood preservatives2012In: Wood and Fiber Science, ISSN 0735-6161, Vol. 44, no 1, p. 85-93Article in journal (Refereed)
    Abstract [en]

    An experiment was conducted on commercially heat-treated (HT) Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] Karst.) sapwood collected from Ht Wood AB, Arvidsjaur, Sweden. Secondary treatment on HT wood was performed in laboratory scale by impregnating with water-repellent preservatives (a commercial one and pine tar) to evaluate their retention and different moisture-related properties. Preservative solutions were impregnated using a simple and effective method. Wood samples were heated at 170°C in a dry oven and were immediately immersed in preservative solutions. Considerable retention was observed in HT wood, particularly in pine. Moisture adsorption properties were measured after conditioning in a high-humidity environmental chamber (4°C and 84% RH). Experimental results showed that secondary treatment enhanced moisture excluding efficiencies by decreasing equilibrium moisture content, suggesting better hydrophobicity. Soaking test in water showed that antiswelling and water repellence efficiencies improved, especially in tar-treated wood. In addition, this type of treatment significantly decreased water absorption. It was also possible to decrease volumetric swellings. Thus, secondary treatment of HT wood with preservative, in particular with tar, improved dimensional stability and water repellency.

  • 90.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Hagman, Olle
    Luleå University of Technology.
    Cloutier, Alain
    Laval University, Canada.
    Fang, Chang-Hua
    Laval University, Canada.
    Elustondo, Diego
    Luleå University of Technology.
    Anatomical properties and process parameters affecting blister/blow formation in densified European aspen and downy birch sapwood boards by thermo-hygro-mechanical compression2013In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 48, no 24, p. 8571-8579Article in journal (Refereed)
    Abstract [en]

    Approximately, 13.5 % of the standing volume of productive forest land in Sweden is covered by birch and aspen, which provides the vast potential to produce value-added products such as densified wood. This study shows whether it is possible to densify those species with a thermo-hygro-mechanical (THM) process using heat, steam, and pressure. In this process, transverse compression on thin European aspen (Populus tremula) and downy birch (Betula pubescens) boards was performed at 200 °C with a maximum steam pressure of 550 kPa. To obtain a theoretical 50 % compression set, the press’s maximum hydraulic pressure ranged from 1.5 to 7.3 MPa. Preliminary tests showed that ~75 % of the birch boards produced defects (blisters/blows) while only 25 % of the aspen boards did. Mainly, radial delamination associated with internal checks in intrawall and transwall fractures caused small cracks (termed blisters) while blows are characterized by relatively larger areas of delamination visible as a bumpy surface on the panel. Anatomical investigations revealed that birch was more prone to those defects than aspen. However, those defects could be minimized by increasing the pre-treatment time during the THM processing.

  • 91.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Sehlstedt-Persson, Margot
    Luleå University of Technology.
    Hansson, Lars
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Evaluation of preservative distribution in thermally modified European aspen and birch boards using computed tomography and scanning electron microscopy2013In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 59, no 1, p. 57-66Article in journal (Refereed)
    Abstract [en]

    The aim of this experiment was to impregnate thermally modified wood using an easy and cost-effective method. Industrially processed thermally modified European aspen (Populus tremula L.) and birch (Betula pubescens Ehrh.) were collected and secondarily treated at the laboratory scale with the preservatives tung oil, pine tar and Elit Träskydd (Beckers) using a simple and effective method. Preservative uptake and distribution in sample boards were evaluated using computed tomography (CT) and scanning electron microscopy (SEM) techniques. Preservative uptake and treatability in terms of void volume filled were found the highest in Beckers and the lowest in tung oil-treated samples. Thermally modified samples had lower treatability than their counterpart control samples. More structural changes after thermal modification, especially in birch, significantly reduced the preservative uptake and distribution. The differences of preservatives uptake near the end grain were high and then decreased near the mid position of the samples length as compared with similar type of wood sample. Non-destructive evaluation by CT scanning provided a very useful method to locate the preservative gradients throughout the sample length. SEM analysis enabled the visualization of the preservative deposits in wood cells at the microstructural level.

  • 92.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Sehlstedt-Persson, Margot
    Luleå University of Technology.
    Karlsson, Olov
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Uneven distribution of preservative in kiln-dried sapwood lumber of Scots pine: Impact of wood structure and resin allocation2012In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 66, no 2, p. 251-258Article in journal (Refereed)
    Abstract [en]

    Scots pine (Pinus sylvestris L.) sapwood lumber was collected after kiln drying and preservative treatment with Celcure AC 800 (a copper-amine wood preservative). Distribution of the preservative throughout the lumber was visually examined. Not all, but some samples showed specific localized areas without any preservative distribution throughout their entire length. Those samples were assessed further for anatomical properties, specifically in impregnated and unimpregnated areas. Additional study was conducted on the morphological nature and redistribution of lipophilic extractives using three different histochemical staining methods. Intrinsic wood properties – especially the frequency of axial resin canals and the percentage of canals blocked – were found to be responsible for the irregular distribution of the preservative. Furthermore, the inability to create continuous and frequent interstitial spaces due to the collapse of thin-walled ray cells throughout the lumber resulted in un-even distribution of preservatives. Staining techniques were useful to localize places with more or less abundance of extractives (e.g., fats) in impregnated and unimpregnated wood, which varied considerably. Histochemical observations revealed information pertaining to the kiln dry specific distribution and redistribution of extractives between the areas. Moreover, resin reallocation and modification in ray parenchyma and resin canals induced by kiln drying would be another reason for the impregnation anomalies.

  • 93.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Sehlstedt-Persson, Margot
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Development of a new rapid method for mould testing in a climate chamber: preliminary tests2013In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 71, no 4, p. 451-461Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to develop fast, simple and robust solid wood mould testing methods for the use in small-scale laboratory tests. The objective was to investigate mould susceptibility of different wood materials within the batches. The proposed method is based on natural contamination of non-sterile surfaces in climates conducive to mould growth. For this purpose, a climate chamber with regulated temperature and relative humidity was used. The conditioning chamber was divided into upper and lower chamber by a thin layer of stainless steel placed horizontally above the fan to minimise air circulation to the sample in the upper compartment. Mould-infected samples from outdoor tests were used as a source of mould inocula, and test trials were conducted on Scots pine (Pinus sylvestris L.) sapwood. Samples were suspended from the top of the upper chamber, and the chamber was exposed to different temperature and humidity levels. Severe mould infestation was observed after 12–14 days of incubation. Visual mould rating was then performed. Regardless of some constraints, this test method was very simple, fast, and effective. More importantly, unlike other test methods, it closely models mould infestation as it would occur under natural condition.

  • 94.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Sehlstedt-Persson, Margot
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Mould susceptibility of Scots pine (Pinus sylvestris L.) sapwood: Impact of drying, thermal modification, and copper-based preservative2013In: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, Vol. 85, p. 284-288Article in journal (Refereed)
    Abstract [en]

    The development of mould on wood surfaces depends on several factors. Although mould does not affect the mechanical properties of wood, it greatly reduces the aesthetic value of wood such as the sapwood of Scots pine (Pinus sylvestris L.), which is very prone to mould. In addition, adverse health effects of mould on humans are a great concern. Different types of dried and treated wood were used to observe whether they had enhanced durability against mould following an accelerated laboratory test method in a climate chamber. Samples were green, air-dried, industrially thermally modified, treated with copper-based preservative, and kiln-dried wood, which were tested within a single test run. The test produced the following main results: The thermal modification increased the durability of the wood, and the protective effectiveness of alternative treatments was comparable to that of commercially available copper-based treatment. However, the initial moisture content of the samples during mould exposure had a great influence on the onset of mould growth. The risk of mould susceptibility of industrial kiln-dried lumber can be reduced by drying using the double-layering technique and planing off the nutrient enriched evaporation surfaces.

  • 95.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Yang, Qian
    Luleå University of Technology.
    Sehlstedt-Persson, Margot
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Accelerated Mold Test on Dried Pine Sapwood Boards: Impact of Contact Heat Treatment2013In: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, Vol. 33, no 3, p. 174-187Article in journal (Refereed)
    Abstract [en]

    We test the hypothesis that the combination of kiln drying of double-stacked boards and contact heat treatment will reduce the susceptibility of treated boards to colonization by mold fungi. Winter-felled Scots pine (Pinus sylvestris L.) sapwood boards were double-stacked in an industrial kiln in ''sapwood out'' and ''sapwood in'' positions. Dried samples were then contact heat-treated using a hot press at three different temperatures (140°C, 170°C, and 200°C) for three different periods (1, 3, and 10 min). An accelerated mold test was performed in a climate chamber where naturally mold-infected samples were used as a source of mold inocula. Contact heat treatment degraded the saccharides that accumulated at dried surfaces, and reduced the mold growth. The threshold temperature and time for inhibiting mold growth were 170°C for 10 min. However, for industrial application, the most feasible combination of temperature and time would be 200°C for 3 min. We concluded that double stacking/contact heat treatment used is an environmentally friendly alternative to chemicals for reducing mold on Scots pine sapwood boards.

  • 96.
    Ahmed, Suhail
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Sun, Hong
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Developing a Model for Managing Production Performance of Small and Medium Enterprises in Sweden2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The study developed a model for production performance management of small and medium enterprises (SMEs) in Sweden. The developed model works for assessing, follow up and improvement in production performance. SMEs differ in size, structure, culture, competition, management practices, resource availability and lot more when compared with large organizations. SMEs also lack in effective performance management framework as most of the framework developed are designed for large organizations.

     

    Production is core and critical value adding process especially for SMEs manufacturer for their survival and growth. SMEs are more motivated with doing rather than measuring it. Taking all these consideration a comprehensive model is developed which consists of four major steps. The model starts with studying of company’s strategy, and then there are steps for design of production performance measurement which works for identifying details strategically aligned performance measures. Benchmarking step is included to compare performance with best practices, finally measurements results are analysed and improvement actions are taken to continuously improve the production performance.

     

    Developed model based on literature study, multiple case study (three case studies) are being conducted to check model applicability. The result of case studies supports the applicability and formulated problem is also well-answered by developed model.

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  • 97.
    Ahmedi, Figene
    et al.
    University of Prishtina, Serbia.
    Ahmedi, Lule
    University of Prishtina, Serbia.
    O'Flynn, Brendan
    Tyndall National Institute, Ireland;University College Cork, Ireland.
    Kurti, Arianit
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM).
    Tahirsylaj, Sylë
    Hydrometeorological Institute of Kosova, Serbia.
    Bytyçi, Eliot
    University of Prishtina, Serbia.
    Sejdiu, Besmir
    University of Prishtina, Serbia.
    Salihu, Astrit
    University of Prishtina, Serbia.
    InWaterSense: An Intelligent Wireless Sensor Network for Monitoring Surface Water Quality to a River in Kosovo2018In: International Journal of Agricultural and Environmental Information Systems, ISSN 1947-3192, Vol. 9, no 1, p. 39-61Article in journal (Refereed)
    Abstract [en]

    A shift in water monitoring approach from traditional grab sampling to novel wireless sensors is gaining in popularity not only among researchers but also in the market. These latest technologies readily enable numerous advantageous monitoring arrangements like remote, continuous, real-time, and spatially-dense and broad in coverage measurements, and identification of long-term trends of parameters of interest. Thus, a WSN system is implemented in a river in Kosovo as part of the InWaterSense project to monitor its water quality parameters. It is one of the first state of the art technology demonstration systems of its kind in the domain of water monitoring in developing countries like Kosovo. Water quality datasets are transmitted at pre-programmed intervals from sensing stations deployed in the river to the server at university via the GPRS network. Data is then made available through a portal to different target groups (policy-makers, water experts, and citizens). Moreover, the InWaterSense system behaves intelligently like staying in line with water quality regulatory standards.

  • 98.
    Ahmetovic, Dario
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Capri, Mirlind
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Hållfasthetsanalys av draglåda för tillverkning av betongslipers för järnvägar2018Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
    Abstract [sv]

    Betongslipers är ett element i den moderna järnvägens uppbyggnad. Det har ersatt det traditionella virkesmaterialet som har ett antal nackdelar gentemot betong. Vid tillverkning av betongslipers förspänns armeringslinor med en kraft på 500 kN innan cementet gjuts in i produktionslinans formar. Undersökningen kommer in i bilden då en svetsad draglåda, där armeringslinorna är låsta, belastas av förspänningskraften. Uppdraget blir att analysera spänningsflödet i draglådan för att se var de största spänningarna förekommer. Detta görs genom en FEM-analys av hela konstruktionen samt hållfasthetsberäkningar av enbart gängorna.

    Slutsatsen som fastställdes var att analysen av konstruktionen resulterade att förspänningskraften inte påverkade gängorna eller svetsarna så pass kritisk att en allvarlig deformation skulle ske.

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  • 99.
    Aissani, D.
    et al.
    University of Bejaia, Algeria.
    Flammini, Francesco
    University of Maryland University College (UMUC) Europe, Germany.
    Editorial2017In: International Journal of Critical Computer-Based Systems, ISSN 1757-8779, E-ISSN 1757-8787, Vol. 7, no 1, p. 1-3Article in journal (Refereed)
  • 100.
    Akeab, Imad
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Accurate techniques for 2D electromagnetic scattering2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis consists of three parts. The first part is an introduction and referencessome recent work on 2D electromagnetic scattering problems at high frequencies. It alsopresents the basic integral equation types for impenetrable objects. A brief discussionof the standard elements of the method of moments is followed by summaries of thepapers.Paper I presents an accurate implementation of the method of moments for a perfectlyconducting cylinder. A scaling for the rapid variation of the solution improves accuracy.At high frequencies, the method of moments leads to a large dense system of equations.Sparsity in this system is obtained by modifying the integration path in the integralequation. The modified path reduces the accuracy in the deep shadow.In paper II, a hybrid method is used to handle the standing waves that are prominentin the shadow for the TE case. The shadow region is treated separately, in a hybridscheme based on a priori knowledge about the solution. An accurate method to combinesolutions in this hybrid scheme is presented.

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