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  • 1.
    A. Oliveira, Roger
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    S. Salles, Rafael
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Rönnberg, Sarah K.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Deep Learning for Power Quality with Special Reference to Unsupervised Learning2023Inngår i: 27th International Conference on Electricity Distribution (CIRED 2023), IEEE, 2023, s. 935-939, artikkel-id 10417Konferansepaper (Fagfellevurdert)
  • 2. A. Taleghani, Pouria
    Laboratory Test on Thermal Spalling and Cracking Around Cylindrical Opening in Rock under Bi-axial Loading Condition2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    A series of laboratory scale studies has been conducted to assess the thermal response of common rock types in Fennoscandinavia. The main objective of this experiment was to investigate experimentally the effect of initial compressive stress on thermal spalling and determine the mechanism causing thermal damage (spalling and fracturing) in rock observed in laboratory experiments. Seven tests were carried out including oven-dried and water-stored rock blocks, with and without applying bi-axial stress on three rock types, granite, gabbro and schist.

    Fulltekst (pdf)
    FULLTEXT02
  • 3.
    A., Trubetskaya
    et al.
    National University of Ireland Galway.
    G. R., Surup
    University of Agder.
    Forsberg, Fredrik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    T., Attard
    University of York.
    A., Hunt
    Khon Kaen University.
    V., Budarin
    University of York.
    V., Abdelsayed
    National Energy Technology Laboratory.
    D., Shekhawat
    National Energy Technology Laboratory.
    The Effect of Wood Composition and Supercritical CO2 Extraction on the Charcoal Production2019Inngår i: 2019 AIChE Annual Meeting proceedings, American Institute of Chemical Engineers, 2019, artikkel-id 552cKonferansepaper (Annet vitenskapelig)
    Abstract [en]

    This work demonstrated that the coupling of supercritical carbon dioxide extraction with slow pyrolysis is effective to remove over half of extractives from low quality wood and to generate biochar from remaining solid wood fractions. The high yields of extractives from supercritical carbon dioxide extraction illustrates the potential utilizing of low quality wood as an alternative feedstock for the sustainable production of value-added chemicals. Results showed that supercritical carbon dioxide extraction has neither a strong impact on the physical properties of original wood nor on the yield of solid biochar. These results are promising as they show that the biochar obtained for this renewable feedstock could be used as an alternative to fossil-based coke in applications including ferroalloy industries. Moreover, the heat treatment temperature and supercritical carbon dioxide extraction had a significant impact on the tar yields, leading to the increase in naphthalene, polycyclic aromatic hydrocarbons, aromatic and phenolic fractions with the greater temperature. The differences in gasification reactivity and dielectric properties of solid biochars, composition and yields of liquid products of non-treated pinewood and extracted wood fraction emphasize the impact of supercritical carbon dioxide extraction on the pyrolysis process. 

  • 4.
    Aakjær, Mia
    et al.
    Department of Drug Design and Pharmacology, Pharmacovigilance Research Center, University of Copenhagen, Copenhagen, Denmark.
    De Bruin, Marie Louise
    Department of Pharmacy, Copenhagen Centre for Regulatory Science (CORS), University of Copenhagen, Copenhagen, Denmark; Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Utrecht, The Netherlands.
    Kulahci, Murat
    Luleå tekniska universitet, Institutionen för ekonomi, teknik, konst och samhälle, Industriell ekonomi. Department of Applied Mathematics and Computer Science, Technical University of Denmark, Lyngby, Denmark.
    Andersen, Morten
    Department of Drug Design and Pharmacology, Pharmacovigilance Research Center, University of Copenhagen, Copenhagen, Denmark.
    Surveillance of Antidepressant Safety (SADS): Active Signal Detection of Serious Medical Events Following SSRI and SNRI Initiation Using Big Healthcare Data2021Inngår i: Drug Safety, ISSN 0114-5916, E-ISSN 1179-1942, Vol. 44, s. 1215-1230Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Introduction The current process for generating evidence in pharmacovigilance has several limitations, which often lead to delays in the evaluation of drug-associated risks.

    Objectives In this study, we proposed and tested a near real-time epidemiological surveillance system using sequential, cumulative analyses focusing on the detection and preliminary risk quantification of potential safety signals following initiation of selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs).

    Methods We emulated an active surveillance system in an historical setting by conducting repeated annual cohort studies using nationwide Danish healthcare data (1996–2016). Outcomes were selected from the European Medicines Agency's Designated Medical Event list, summaries of product characteristics, and the literature. We followed patients for a maximum of 6 months from treatment initiation to the event of interest or censoring. We performed Cox regression analyses adjusted for standard sets of covariates. Potential safety signals were visualized using heat maps and cumulative hazard ratio (HR) plots over time.

    Results In the total study population, 969,667 new users were included and followed for 461,506 person-years. We detected potential safety signals with incidence rates as low as 0.9 per 10,000 person-years. Having eight different exposure drugs and 51 medical events, we identified 31 unique combinations of potential safety signals with a positive association to the event of interest in the exposed group. We proposed that these signals were designated for further evaluation once they appeared in a prospective setting. In total, 21 (67.7%) of these were not present in the current summaries of product characteristics.

    Conclusion The study demonstrated the feasibility of performing epidemiological surveillance using sequential, cumulative analyses. Larger populations are needed to evaluate rare events and infrequently used antidepressants.

  • 5.
    Aalipour, Mojgan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Human Factors Approach for Maintenance Improvement2015Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The purpose of this research work is to explore and describe human factors affectingmaintenance execution. To achieve the purpose of this study, the influencing factors have been identified using a literature survey. They have been categorized into four main groups namely organizational, workplace, job and individual factors. The Analytical Hierarchy Process (AHP) method is employed on data questionnaires to rank the priority of the factors. The interrelationships between these factors have been recognized by theInterpretive Structural Modelling (ISM) model. In the present case studies, MICMAC1analysis technique is also implemented for identifying the driving, dependent, linkage and autonomous factors. The data was collected through a questionnaire survey involving the participation of 16 and 25 maintenance staff and 10 mining experts in Swedish and Iranian mines, respectively. Within the study, it has been identified that the temperature, work layout, tools design and tools availability are the most important factors in both mines related to these categories. However, the significant factors in the organizational and individual categories are different in the selected mines. The effect of workplace factors on the maintainability of mining equipment is discussed and thereafter a methodology for maintainability management in the design and operation phases is developed. In the thirdcase study HEART2 is applied to estimate the probability of human error occurring duringmaintenance execution in an Iranian cable company. This research supports maintenance management to gain knowledge of human factors that affect maintenance execution. Further, this understanding could be useful in the development of strategies to improve the execution of maintenance.Keywords: Human Factors, Maintenance Management, Human Reliability, HumanPerformance, AHP, ISM, MICMAC, HEART

    Fulltekst (pdf)
    FULLTEXT01
  • 6.
    Aalipour, Mojgan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Ayele, Yonas Zewdu
    Department of Engineering and Safety, UiT The Arctic University of Norway, Tromsø.
    Barabadi, Abbas
    Tromsø University, Department of Engineering and Safety, UiT The Arctic University of Norway, Tromsø.
    Human reliability assessment (HRA) in maintenance of production process: a case study2016Inngår i: International Journal of Systems Assurance Engineering and Management, ISSN 0975-6809, E-ISSN 0976-4348, Vol. 7, nr 2, s. 229-238Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Human reliability makes a considerable contribution to the maintenance performance, safety, and cost-efficiency of any production process. To improve human reliability, the causes of human errors should be identified and the probability of human errors should be quantified. Analysis of human error is very case-specific; the context of the field should be taken into account. The aim of this study is to identify the causes of human errors and improve human reliability in maintenance activities in the cable manufacturing industry. The central thrust of this paper is to employ the three most common HRA techniques—human error assessment and reduction technique, standardized plant analysis risk-human reliability, and Bayesian network—for estimating human error probabilities and then to check the consistency of the results obtained. The case study results demonstrated that the main causes of human error during maintenance activities are time pressure, lack of experience, and poor procedure. Moreover, the probabilities of human error, obtained by employing the three techniques, are similar and consistent

  • 7.
    Aalipour, Mojgan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Barabadi, Abbas
    Tromsø University, University of Tromsø - The Arctic University of Norway.
    Work place factors effect on maintainability in challenging operating conditions2015Inngår i: 2015 IEEE International Conference on Industrial Engineering and Engineering Management (IEEM): Singapore, 6-9 Dec. 2015, Piscataway, NJ: IEEE Communications Society, 2015, s. 767-771, artikkel-id 7385751Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Some industries such as mining industry create complex and challenging work place for maintenance crews. For example in an underground mine, for some machines, heavy maintenance tasks must be performed on site in a limited workspace in a harsh environment, including dust and improper illumination. Such operating conditions can increase the health, safety, and environment (HSE) risk, reduce the availability of the machines and increase the life cycle cost of equipment. A review of current mining equipment design and maintenance procedure confirms that considerable reduction in HSE risk, as well as substantial cost savings, can be achieved by considering human factors. This study discusses the effect of workplace factors on the maintainability of mining equipment. It presents the results from questionnaires on the effect of work place factors on maintainability performance given to maintenance staff at two mines, one in northern Sweden and the other in Iran.

  • 8.
    Aalipour, Mojgan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Singh, Sarbjeet
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Identification of Factors affecting Human performance in Mining Maintenance tasks2014Inngår i: Proceedings of the 3rd international workshop and congress on eMaintenance: June 17-18 Luleå, Sweden : eMaintenance, Trends in technologies & methodologies, challenges, possibilites and applications / [ed] Uday Kumar; Ramin Karim; Aditya Parida; Philip Tretten, Luleå: Luleå tekniska universitet, 2014, s. 71-76Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper investigates the factors affecting humanperformance in maintenance task in mining sector. Theobjective is identify various factors and to classify them asdriving (strong driving power and weak dependence) anddependent factors (weak driving power and strongdependence). The factors were identified through literaturesurvey and are ranked using mean score of data questionnaire.The reliability of measures is pretested by applyingCronbach’s alpha coefficient to responses to a questionnairegiven to maintenance personnel. The interrelationshipsbetween human factors have been recognized by interpretivestructural modeling (ISM). Further, these factors have beenclassified using matrice d'impacts croises-multiplicationappliqué à un classement (MICMAC) analysing. This casestudy will figure out the factors affecting human performancefor deriving maintenance management insights to improveproductivity in the mining sector. Further, this understandingmay be helpful in framing the policies and strategies formining industry. Temperature, lighting, documentation,communication and fitness are driving factors. Moreover,Work layout, tools availability, complex tasks, time pressure,safety, boss decisions, training, fatigue and motivation havestrong driving power as well as high dependencies and itcomes under the category of linkage factors.

    Fulltekst (pdf)
    FULLTEXT01
  • 9.
    Aaltonen, Harri
    et al.
    Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, FI-00076 Espoo, Finland.
    Sierla, Seppo
    Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, FI-00076 Espoo, Finland.
    Kyrki, Ville
    Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, FI-00076 Espoo, Finland.
    Pourakbari-Kasmaei, Mahdi
    Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, FI-00076 Espoo, Finland.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap. Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, FI-00076 Espoo, Finland.
    Bidding a Battery on Electricity Markets and Minimizing Battery Aging Costs: A Reinforcement Learning Approach2022Inngår i: Energies, E-ISSN 1996-1073, Vol. 15, nr 14, artikkel-id 4960Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Battery storage is emerging as a key component of intelligent green electricitiy systems. The battery is monetized through market participation, which usually involves bidding. Bidding is a multi‐objective optimization problem, involving targets such as maximizing market compensation and minimizing penalties for failing to provide the service and costs for battery aging. In this article, battery participation is investigated on primary frequency reserve markets. Reinforcement learning is applied for the optimization. In previous research, only simplified formulations of battery aging have been used in the reinforcement learning formulation, so it is unclear how the optimizer would perform with a real battery. In this article, a physics‐based battery aging model is used to assess the aging. The contribution of this article is a methodology involving a realistic battery simulation to assess the performance of the trained RL agent with respect to battery aging in order to inform the selection of the weighting of the aging term in the RL reward formula. The RL agent performs day-ahead bidding on the Finnish Frequency Containment Reserves for Normal Operation market, with the objective of maximizing market compensation, minimizing market penalties and minimizing aging costs.

  • 10.
    Aaltonen, Harri
    et al.
    Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, FI-00076 Espoo, Finland.
    Sierla, Seppo
    Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, FI-00076 Espoo, Finland.
    Subramanya, Rakshith
    Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, FI-00076 Espoo, Finland.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap. Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, FI-00076 Espoo, Finland; International Research Laboratory of Computer Technologies, ITMO University, 197101 St. Petersburg, Russia.
    A simulation environment for training a reinforcement learning agent trading a battery storage2021Inngår i: Energies, E-ISSN 1996-1073, Vol. 14, nr 17, artikkel-id 5587Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Battery storages are an essential element of the emerging smart grid. Compared to other distributed intelligent energy resources, batteries have the advantage of being able to rapidly react to events such as renewable generation fluctuations or grid disturbances. There is a lack of research on ways to profitably exploit this ability. Any solution needs to consider rapid electrical phenomena as well as the much slower dynamics of relevant electricity markets. Reinforcement learning is a branch of artificial intelligence that has shown promise in optimizing complex problems involving uncertainty. This article applies reinforcement learning to the problem of trading batteries. The problem involves two timescales, both of which are important for profitability. Firstly, trading the battery capacity must occur on the timescale of the chosen electricity markets. Secondly, the real-time operation of the battery must ensure that no financial penalties are incurred from failing to meet the technical specification. The trading-related decisions must be done under uncertainties, such as unknown future market prices and unpredictable power grid disturbances. In this article, a simulation model of a battery system is proposed as the environment to train a reinforcement learning agent to make such decisions. The system is demonstrated with an application of the battery to Finnish primary frequency reserve markets.

  • 11. Aaltonen, Sanna
    et al.
    Sunnari, Vappu
    Sexual harassment: conceptual and methodological reflections2001Inngår i: Youth on the threshold of 3rd millennium, Joensuu: Joensuun yliopisto , 2001, s. 31-44Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 12.
    Aamir, Muhammad Haseeb
    et al.
    Ecole Nationale Supérieure de Géologie, GeoRessources, University of Lorraine, Vandoeuvre-lès-Nancy, France; University of Engineering and Technology, Lahore, Punjab, Pakistan.
    Gonçalves, Pedro Pereira
    Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Peñalolén, Santiago, Chile.
    Otsuki, Akira
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik. Ecole Nationale Supérieure de Géologie, GeoRessources, University of Lorraine, Vandoeuvre-lès-Nancy, France; Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Peñalolén, Santiago, Chile; Neutron Beam Technology Team, RIKEN Center for Advanced Photonics, RIKEN, Wako, Saitama, Japan.
    Complementary results of non-destructive elemental assay and liberation analysis of waste printed circuit boards2024Inngår i: Non-Destructive Material Characterization Methods / [ed] Otsuki, Akira; Jose, Seiko; Mohan, Manasa; Thomas, Sabu, Elsevier , 2024, s. 767-782Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 13. Aarabi, Narjes
    et al.
    Bromideh, Ali Akbar
    The impact of e-commerce on the Iranian insurance companies2006Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The conditions for doing business are rapidly changing. The Internet and related advances in information technology significantly affect financial services in general and insurance markets and institutions in particular. The growing importance of e-commerce represents a watershed event for insurance markets and institutions, as it does for most industries. By lowering information costs, e-commerce will enable insurers to classify, underwrite, and price risk as well as settle claims more accurately and efficiently. Overall, the Internet will significantly enhance the efficiency of insurance markets and institutions and benefit consumers by lowering transaction and information costs. The effects of e-commerce are the subjects of intense debate in insurance industry. The foundation for the purpose of this research has been created by a prospective study to explore the impact of application of e-commerce on the Iranian insurance industry. In order to fulfill the purpose of this study, a frame of reference has been emerged based on a vast literature review. With the focus at quantitative research as a general approach and descriptive research as the type of research in this study, a structured questionnaire was used as the data collection instrument. To accomplish this, a survey of 258 people (in almost all active insurance companies in Iran) has been carried out. The respondents from almost every department within the targeted insurance companies were randomly chosen. We have focused on the perception of insurers regarding the subject of study, and thus, the perception of other stakeholder such as insurance agents/brokers and even their customers have been suggested for future research, due to limitation and demarcation of this research. This dissertation has been organized in the seven chapters. An introduction this study, problem statements and research questions were presented in chapter one. The second chapter was devoted to literature review. The emerged frame of reference was provided in the third chapter and our research methodology was discussed in the fourth chapter. Data presentation and analysis were done in accordance with the research questions and the frame of reference in chapter five and six, respectively. Finally, in the last chapter findings and conclusions were drawn by answering the research questions. With respect to the findings, we conclude that the Iranian insurance companies were positively looked at e-commerce and its application in their companies. Their attitude and views toward e-commerce was positive so that they found that e-commerce would be an opportunity rather than a challenge or even a threat for insurance industry. They highly believed that e- commerce would affect on insurance companies and, thus, their companies should embrace e-commerce. Lack of skilled staffs in e-commerce application and scarcity of IT experts were the most infrastructure requirements which they found that the Iranian insures were suffering from. Whereas they were well equipped with hardware and networking as well as general and professional insurance software required in e-commerce applications. Lagging of other supportive sectors (e.g., e-Banking and Telecommunications), lack of appropriate legislation and regulation (e.g., copy right, digital signature, …), low Internet usage and fewer users, traditionally attitudes and views over the companies and scarcity of skilled staffs were the five top major obstacles which would hinder the Iranian insurers to embrace e-commerce. E-commerce is potentially applicable to marketing and sales as well as R&D with respect to insurance value chain. On the other hand, as far as insurance products concern, auto (motor) insurance, marine and aviation, life insurance and fire insurance were highly perceived to suitable to e- commerce (sale online). Finally, the Iranian insurance companies were chiefly believed that in the case of e-commerce application they would get these top five benefits: brand and image promotion (as a pioneer and modern company), extended corporation with partners (specially in the reinsurance cases), lower invest for establishing the sales and after sales services network, cost reduction in value chain management (e.g. product/service development) and decentralization and no restrictions imposed by national borders.

    Fulltekst (pdf)
    FULLTEXT01
  • 14.
    Aardal, Karen
    et al.
    Department of Mathematics, Linköping Institute of Technology.
    Ari, Aysen
    Luleå tekniska universitet.
    Decomposition principles applied to the dynamic production and work-force scheduling problem1987Inngår i: Engineering Costs and Production Economics, ISSN 0167-188X, E-ISSN 1878-4011, Vol. 12, nr 1-4, s. 39-49Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One of the most important problems in the production and inventory planning field, is the scheduling of production and work force in a dynamic environment. Although this problem can be formulated as a linear program, it is often quite difficult to solve directly, due to its large scale. Instead, it might be fruitful to use a decomposition approach. Decomposition, in general, means decomposing a difficult problem into several easier, or a sequence of easier problems which are later coordinated to reconstruct the original problem.In this report we discuss several possibilities of applying the most common decomposition principles, namely Benders (primal) and Datnzig-Wolfe (dual), as well as a relatively new decomposition method, called cross decomposition, to the dynamic, multiproduct production and employment planning problem. A number of special cases are also presented.

  • 15.
    Aardal, Karen
    et al.
    CORE, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
    Ari, Aysen
    Luleå tekniska universitet.
    On the resemblance between the Kornai-Liptak and cross decomposition techniques for block-angular linear programs1990Inngår i: European Journal of Operational Research, ISSN 0377-2217, E-ISSN 1872-6860, Vol. 46, nr 3, s. 393-398Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper the resemblance is demonstrated between the master- and subproblems generated by the Kornai-Liptak algorithm and the subproblems obtained by using the cross decomposition method on linear optimization problems with block-angular structure. The significance of the similarity between these two algorithms becomes apparent considering the main disadvantage attributed to cross decomposition. In cross decomposition a master problem has to be solved from time to time since the subproblems alone do not always give a converging sequence of primal and dual solutions. But if the cross decomposition algorithm is modified in such a way that the successive primal and dual subproblem solutions are taken into consideration with equal weights, this results in the Kornai-Liptak algorithm for which convergence is guaranteed

  • 16.
    Aarflot, Markus
    et al.
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle.
    Jangstam, Pontus
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle.
    Future Logistical Services from Connected Vehicles: A Case Study at Scania CV AB2017Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The road based transportation operations are growing rapidly, but the current infrastructure cannot sustain the entire growth. At the same time vehicle utilisation and fill rates are low. Improved efficiency of the operations is a necessary way forward for road based transportation. Parallel to this, heavy vehicle producers are currently improving the efficiency with services accompanying the product that are focused on the driver and the vehicle performance. However, the data from connected vehicles required for these services only entail a small amount of the operational data generated by connected vehicles. The case study aims to answer how to use connected vehicle operational data in order to suggest value adding services in a dynamic road distribution system. The applied methodology is an inductive study with an explanatory approach to map the current and future service offerings of the case company. This knowledge is combined with an exploratory approach with interviews of transport planners and theories of Lean and fleet management. Primarily, it is concluded that the perspective of operational data requires widening. Considering not only driver and vehicle operations but rather the entire transport operation of a company. It is also concluded that value creation with operational data is possible during three phases of fleet management. First, if knowledge about order data is accessible, the planning of transportations can be improved using route optimisation and operations research. Secondly, it is possible to create value during the execution phase, throughless manual supervision and communication by transport planners. Lastly, both the currently used operational data and further data usage can contribute to a better understanding of the performance of a fleet operation and facilitate for continuous improvements during an evaluation phase.

    Fulltekst (pdf)
    fulltext
  • 17.
    Aarnio, Laura
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik.
    Att utveckla digital kompetens hos de yngsta barnen: Ett förskollärarperspektiv på arbetet med 1- och 2-åringar2023Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Denna studie tar sin grund i det sociokulturella perspektivet och fokuserar på digital kompetens hos de yngsta barnen utifrån ett förskollärarperspektiv. Det ansågs som intressant att ta reda på hur förskolan arbetar med digitalisering med 1- och 2-åringar på ett sätt som lägger grunden för det livslånga lärandet och ger förutsättningar för individen som en aktiv deltagare i det digitala samhället. För att kunna svara på studiens syfte och frågeställningar föll valet på att intervjua verksamma förskollärare som arbetar på avdelningar för yngre barn. 

    Tillgång till digitala verktyg och utforskande både självständigt och tillsammans med andra framhävs i denna studie som centralt. Förskollärare har lite olika perspektiv på arbetssätt och på vad som är viktigt för de yngsta barnen att lära sig när det gäller digital teknik och kompetens. Förskollärarens eget engagemang och kompetens påverkar hur undervisningen ser ut. Det är viktigt att kunna balansera mellan att ge barnen möjligheter att utforska tillsammans och självständigt samtidigt som läraren finns tillgänglig och närvarande för att vid behov kunna erbjuda stöd samt ta vara på lärandetillfällen. En närvarande och kompetent pedagog har möjligheten att få mycket information kring barnens digitala kompetens samt dem intressen de har. De flesta verksamheterna hade ingen tydlig planering eller strategi för digitalisering utan digital teknik blev ett ständigt närvarande redskap som används kontinuerligt och kompletterar andra områden inom undervisning och lek. Digitala verktyg utvidgar lärmiljön och skapar nya rumsliga dimensioner.

    Fulltekst (pdf)
    fulltext
  • 18. Aaro, Mikael
    Ämnesområdets betydelse för flickors och pojkars talutrymme: en studie om hur talutrymmet fördelas mellan könen inom olika ämnesområden2010Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
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  • 19.
    Aarrevaara, Timo
    et al.
    Helsingfors Universitet.
    Berg, Elisabeth
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Arbetsvetenskap.
    Higher Education and Research: Who should pay?2014Rapport (Fagfellevurdert)
    Fulltekst (pdf)
    FULLTEXT01
  • 20.
    Aarrevaara, Timo
    et al.
    Helsingfors Universitet.
    Berg, Elisabeth
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Arbetsvetenskap.
    Introduction2014Inngår i: Higher Education and Research in Academe: Who should pay?, Luleå: Luleå tekniska universitet, 2014, s. 11-17Kapittel i bok, del av antologi (Annet vitenskapelig)
    Fulltekst (pdf)
    FULLTEXT01
  • 21.
    Aaröe, Olivia
    et al.
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik.
    Ullenius Ekengren, Fanny
    Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik.
    Personers upplevelser av att leva med lungfibros: En litteraturstudie2023Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Bakgrund: Lungfibros är en kronisk respiratorisk sjukdom som kännetecknas av nedsatt lungfunktion och andningssvårigheter. Det finns otillräckliga resurser i form av stöd för personen som drabbats av lungfibros och sjukdomen missförstås av hälso-och sjukvårdspersonal och samhället. Behandlingen är bristfällig och fokuserar i dagsläget på att förebygga, behandla och lindra symtom för att öka livskvaliteten för personen som är drabbad. Det finns utmaningar med vård som enbart fokuserar på symtomlindring och det finns behov av ytterligare insatser för att uppnå en förbättrad livskvalitet hos den enskilda personen med lungfibros. Syfte: Att beskriva personers upplevelser av att leva med lungfibros. Metod: Litteraturstudie med induktiv ansats där tio vetenskapliga artiklar har analyserats med kvalitativ manifest innehållsanalys. Resultat: Analysen resulterade i fem slutkategorier som beskriver personers upplevelser av att leva med lungfibros: en turbulent resa från symtom till diagnos, att känna en inre och yttre påverkan, en förändring och påverkan i det dagliga livet, att ha behov av stöd och information, och att ha funderingar inför en oviss framtid. Slutsats: För personer som lever med lungfibros och deras närstående är stöd, information och copingstrategier avgörande i det dagliga livet. Sjuksköterskan har en viktig roll gällande kommunikation och den bör vara personcentrerad och anpassad till personens behov och takt. Samtal om livets slutskede är nödvändigt för personer med lungfibros, men brister ofta i vård och omvårdnad av denna patientgrupp. 

    Fulltekst (pdf)
    fulltext
  • 22.
    Aas, Gro Hanne
    Luleå tekniska universitet.
    Kvinneforskningspolitiske (pr)øvelser1999Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [no]

    Målsettingen for licentiatuppsatsen er å analysere nordisk kvinneforsknings formuleringer av forskningspolitiske felter, problemstillinger og utfordringer, og gjennom kontakt og diskusjon bidra til samarbeid, diskusjoner og offentlighet om forskingspolitikk i kvinneforskning. Arbeidet har tatt utgangspunkt i relativt nytt materiale fra Danmark, Norge og Sverige. I kap. 1 presenteres prosjektet, problemstillinger og materiale. Kapitlene 2-6 består av innledninger og artikler holdt eller skrevet i løpet av de to senaste åren. Diskusjoner om kjønn og akademia står i fokus i kap. 2 - "Universities have politics". I kap. 3, artikkelen "Gamle og nye drømmer", diskuteres et kvinneforskningspolitiske intervensjonsprosjekt som blev utført for en del år tilbake, og det antydes noen nye omdreiningspunkter for et slikt arbeid. Enkelte perspektiver utdypes i kap. 4, "Kvinneforskningens samfunnskontrakt", hvor termen "kvinneperspektiv" som forskningspolitisk term granskas krtitiskt. De to siste kapitlene tar utgangspunkt i den norske forskningsmeldingen som kom våren 1999. Ut fra tre lesestrategier forsøkes det leses muligheter for kvinneforskningspolitiske strategier. Det ses også på innholdet i regjeringens forskningspolitiske verdidebatt, og det diskuteres mulige intervensjoner i denne ut fra feministiske vitenskaps- og teknologistudier.

  • 23. Aasa, Anna-Karin
    et al.
    Broström, Petter
    Närståendes upplevelse av bemötande från vårdpersonal på en akutpsykiatrisk avdelning2009Independent thesis Advanced level (professional degree), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    FULLTEXT01
  • 24. Aasa, Anna-Karin
    et al.
    Tervaniemi, Anita
    Upplevelsen av att leva med Alzheimers sjukdom i ett tidigt skede: en litteraturstudie2007Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    FULLTEXT01
  • 25.
    Aasa, Björn
    et al.
    Department of Orthopaedics, Surgical and Perioperative Sciences, Umeå University, Norrlandsklinikens hälsocentral, Umeå.
    Berglund, Lars
    Department of Community Medicine and Rehabilitation, Physiotherapy, Umeå University.
    Michaelson, Peter
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Hälsa och rehabilitering.
    Aasa, Ulrika
    Umeå University, Department of Community Medicine and Rehabilitation.
    Individualized Low-Load Motor Control Exercises and Education Versus a High-Load Lifting Exercise and Education to Improve Activity, Pain Intensity, and Physical Performance in Patients With Low Back Pain: A Randomized Controlled Trial2015Inngår i: Journal of Orthopaedic and Sports Physical Therapy, ISSN 0190-6011, E-ISSN 1938-1344, Vol. 45, nr 2, s. 77-85Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Study DesignRandomized controlled trial. BackgroundLow back pain is a common disorder. Patients with low back pain frequently have aberrant and pain-provocative movement patterns that often are addressed with motor control exercises. ObjectiveTo compare the effects of low-load motor control (LMC) exercise and those of a high-load lifting (HLL) exercise. MethodsSeventy participants with recurrent low back pain, who were diagnosed with nociceptive mechanical pain as their dominating pain pattern, were randomized to either LMC or HLL exercise treatments. Participants were offered 12 treatment sessions over an 8-week period. All participants were also provided with education regarding pain mechanisms. MethodsParticipants were assessed prior to and following treatment. The primary outcome measures were activity (the Patient-Specific Functional Scale) and average pain intensity over the last 7 days (visual analog scale). The secondary outcome measure was a physical performance test battery that included 1 strength, 3 endurance, and 7 movement control tests for the lumbopelvic region. ResultsBoth interventions resulted in significant within-group improvements in pain intensity, strength, and endurance. The LMC group showed significantly greater improvement on the Patient-Specific Functional Scale (4.2 points) compared with the HLL group (2.5 points) (P<.001). There were no significant between-group differences in pain intensity (P = .505), strength, and 1 of the 3 endurance tests. However, the LMC group showed an increase (from 2.9 to 5.9) on the movement control test subscale, whereas the HLL group showed no change (from 3.9 to 3.1) (P<.001). ConclusionAn LMC intervention may result in superior outcomes in activity, movement control, and muscle endurance compared to an HLL intervention, but not in pain intensity, strength, or endurance. Registered at ClinicalTrials.gov (NCT01061632).

  • 26.
    Aasa, Björn
    et al.
    Norrlandsklinikens hälsocentral, Umeå.
    Hellqvist, Jonas
    Umeå University, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Berglund, Lars
    Umeå University, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Michaelson, Peter
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Hälsa och rehabilitering.
    Aasa, Ulrika
    Umeå University, Department of Community Medicine and Rehabilitation, Physiotherapy.
    A characterisation of pain, disability, kinesiophobia and physical capacity in patients with predominantly peripherally mediated mechanical low back pain2011Inngår i: Physiotherapy, ISSN 0031-9406, E-ISSN 1873-1465, Vol. 97, nr Suppl. 1, s. eS18-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Purpose: The specific objectives were to: 1) describe the level of pain intensity, disability, activity limitation, kinesiophobia and physical capacity in patients with predominantly peripherally mediated mechanical back pain, and 2) investigate whether differences between these patients in physical and psychosocial factors can be distinguished when the patients are further sub-grouped.Relevance: To improve assessment among patients with chronic low back pain (CLBP) it is important to investigate the prevalence of physical and psychosocial features in homogenous sub-groups.Participants: Seventy-one patients with CLBP, 20-60 years old, with peripherally mediated mechanical pain at the the moment for the study, were included and each patient was sub-classified into one of five sub-groups based on their pain behaviour and functional movement pattern (flexion n=20, flexion/lateral shift, n=11, active extension n=23 , passive extension n=8, and multidirectional pattern n=9).Methods: Data on pain intensity (Visual Analogue Scale), disability (the Roland and Morris Questionnaire), activity limitation (the Patient Specific Functional Scale), kinesiophobia (the Tampa Scale of Kinesiophobia) and physical capacity (lifting capacity and trunk extensor endurance) was collected.Analysis: Mean and standard deviation for parametric and median and interquartile range for non-parametric data were used for descriptive statistics. One-way ANOVA for normally distributed data and Kruskal-Wallis for non-normally distributed data were used for analyses of differences between the sub-groups. The subjects were also divided into two age-groups (20-40 and 41-60 years) and measures of physical capacity were compared to women and men at the ages of 34 and 50, respectively, in the general Swedish population using one sample T-test.Results: The patients reported low to moderate pain intensity (3.1/10±2.4), disability (RMDQ (7.27/24 ±4.2) and kinesiophobia (33.4/68 ±7) and these levels were lower than reported levels in other studies including more heterogenous groups of patients with CLBP. The patiens reported activity limitations (PSFS 13/30±23). Lifting capacity and trunk extensor endurance were significantly lower than in the general population in the youngest age-group. No significant differences in pain intensity, disability, kinesiophobia or physical capacity were found between the sub-groups.Conclusions: This research highlights that patients with predominantly peripherally mediated mechanical back pain may differ from other sub-groups of patients with CLBP (e.g., patients with central sensitization as dominating pain mechanism) regarding physical and psychosocial factors. The individual variation in pain intensity, disability, kinesiophbia and physical capacity among the patients indicates the importance to assess these factors in every patient. Due to the fact that there were few patients in the sub-groups, further research is necessary to explore whether there are differences, that we were not able to disingjish, between patients with different movement patterns.

  • 27.
    Aasa, Björn
    et al.
    Department of Orthopaedics, Surgical and Perioperative Sciences, Umeå University, Norrlandsklinikens hälsocentral, Umeå.
    Sandlund, Jonas
    Michaelson, Peter
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Hälsa och rehabilitering.
    Aasa, Ulrika
    Umeå University, Department of Community Medicine and Rehabilitation.
    Low- versus high-load motor control exercise to reduce disability in patients with persistent peripherally mediated mechanical low back pain2012Inngår i: Rendez vous of hands and minds: 10th International Federation of Orthopaedic Manipulative Physical Therapists’ World conference, Quebec,  1-5 Oct 2012, 2012, nr 2Konferansepaper (Fagfellevurdert)
  • 28. Aasa, Elina
    et al.
    Wikström, Madeleine
    Hur nyttjas och upplevs friskvårdsinsatserna inom en kommun i norra Sverige?: En enkätundersökning med kvalitativt inslag2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Background: In today's society there are increasing demands for performance and efficiency, not least of all in the public sector. Wellness efforts can strengthen employees health and well-being, which is crucial for job performance. Purpose: The purpose of the study was to investigate whether employees in three sectors in one municipality in the north of Sweden had knowledge and utilized wellness initiatives, and how they felt that wellness efforts affected their health. Method: The data collection consisted of a questionnaire that was distributed in two ways, by web and by paper. The questionnaire contained 24 questions, 19 questions with fixed answers and 5 open questions. Sample: The sample of the study consisted of all employees who were 18 years or older in the areas of group housing, day care and psychiatry. All departments are included in the occupation area of support and care. A total of 47 people participated of which 30 were women and 17 men.Results: 92 % were aware that they were offered some kind of wellness effort but only 52 % utilized any wellness initiative that the employer offered. Of those who used the wellness initiative 48 % were satisfied and 52 % were not satisfied. Wellness allowance was the most used wellness initiative, which most utilized for gym membership. The majority of employees wanted a fitness hour during paid working hours. Conclusion: The study showed that most employees do not occupy any wellness initiative although many were aware that they were offered. Most of them wanted more joint activities, including training during working hours.

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  • 29. Aasa, Gabriella
    et al.
    Gillsparr, Malin
    Självkänsla och självaktning: ett försök att öka självkänsla och självaktning hos flickor i årskurs fyra genom gruppstärkande övningar2003Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    FULLTEXT01
  • 30.
    Aasa, Johan
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Linear-Quadratic Regulation of ComputerRoom Air Conditioners2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Data centers operations are notoriously energy-hungry, with the computing and cooling infrastructures drawing comparable amount of electrical power to operate. A direction to improve their efciency is to optimizethe cooling, in the sense of implementing cooling infrastructures controlschemes that avoid performing over-cooling of the servers.Towards this direction, this work investigates minimum cost linearquadratic control strategies for the problem of managing air cooled datacenters. We derive a physical and a black box model for a general datacenter, identify this model from real data, and then derive, present andtest in the eld a model based Linear-Quadratic Regulator (LQR) strategy that sets the optimal coolant temperature for each individual coolingunit. To validate the approach we compare the eld tests from the LQR strategy against classical Proportional-Integral-Derivative (PID) controlstrategies, and show through our experiments that it is possible to reducethe energy consumption with respect to the existing practices by severalpoints percent without harming the servers within the data center fromthermal perspectives.

    Fulltekst (pdf)
    fulltext
  • 31. Aasa, Johan
    et al.
    Skarin, Boel
    Ett källkritiskt användande av dagstidningen i svenskundervisningen: påverkan på motivation och kunskap2002Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
  • 32. Aasa, Martin
    et al.
    Hällström, Alexander
    En mobilstrategis komponenter2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    This bachelor thesis has been produced by the initiative of Luleå municipality, with the focus investigating the content of a mobile strategy. In this thesis, we tried to distil the important aspects of a mobile strategy. The purpose was to study which aspects should or could be part of a mobile strategy. With the help of a theoretical review of the areas: IT-strategy, strategy, mobile strategy, Bring Your Own Device, Mobile device management also Luleå municipalities IT-policy and their IT-Strategy, we produced a theoretical framework. This framework, together with a survey and semi-structured interviews, form the base of the study. The survey consisted of a total of 194 respondents, which corresponds to 3% of the total amount of the employees, and we did 7 interviews with 7 different IT-coordinators on different units. The result shows that a mobile strategy needs to consider following aspects: Bring Your Own Device, Choose Your Own Device, Management system, Technology neutrality, Application management, Stress management, and Overview of fixed telephony.

    Fulltekst (pdf)
    FULLTEXT02
  • 33.
    Aasa, Ulrika
    et al.
    Umeå University, Department of Community Medicine and Rehabilitation.
    Aasa, Björn
    Department of Orthopaedics, Surgical and Perioperative Sciences, Umeå University, Norrlandsklinikens hälsocentral, Umeå.
    Michaelson, Peter
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Hälsa och rehabilitering.
    Sandlund, Jonas
    Effects of low- and high-load motor control exercises on lumbar curvature during stance in patients with low back pain2012Inngår i: Rendez vous of hands and minds: 10th International Federation of Orthopaedic Manipulative Physical Therapists’ World conference, Quebec,  1-5 Oct 2012, 2012, nr 2Konferansepaper (Fagfellevurdert)
  • 34.
    Aaskoven, Mette
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Omvårdnad.
    Hietala, Ulrika
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Omvårdnad.
    Föräldrars upplevelse av att ha ett barn med diabetes typ 12019Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Bakgrund: Typ 1 diabetes är en sjukdom som mer än 500 000 barn och unga under 17 år lever med och kräver livslång behandling. För barnens föräldrar innebär detta en omställning i det dagliga livet och i deras föräldraskap. Föräldrarna kan ha behov av stöttning från vårdpersonal. Syfte: Att beskriva föräldrars upplevelse av att ha ett barn med typ 1 diabetes. Metod: Kvalitativ manifest innehållsanalys användes som analysmetod och 12 vetenskapliga artiklar med kvalitativ ansats ingick i resultatet. Analysen resulterade i fem slutgiltiga kategorier. Resultat: Föräldrar till ett barn med typ 1 diabetes kan uppleva att diagnosen förändrar livet. Vardagen styrs av kontroll och planering vilket leder till många känslor som är svåra att hantera. Föräldrarna behöver tillgänglighet från vårdpersonal och andra för att känna trygghet och för att kunna hantera livet med ett barn med diabetes typ 1. Slutsatser: För att sjuksköterskan ska kunna ge en god omvårdnad är det av betydelse att hen kan relatera till både patienter och anhöriga. Sjukvården har en viktig roll att genom stor tillgänglighet och uppbackning vara ett stöd och därmed vara en trygghet för familjerna i vardagen. Denna studies resultat kan ge en ökad förståelse för föräldrars upplevelse av att ha barn med diabetes typ 1. Det behövs mer kunskap inom området för att sjuksköterskor ska kunna bemöta och stötta familjerna vilket kan leda till förbättrad omvårdnad.

    Fulltekst (pdf)
    fulltext
  • 35. Aasvold, Wenke
    et al.
    Nilsson, Andreas
    Grön IT: en fallstudie av de viktigaste satsningarna inom Grön IT hos organisationer i IT-branschen2010Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    FULLTEXT01
  • 36. Aava, Anette
    et al.
    Söderberg, Martina
    Improved dashboard storage solutions for VCC2008Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This project has been preformed as a master degree thesis in the engineering program Ergonomic Design and Production at Luleå University of Technology (LTU). The project was assigned by Volvo Car Corporation (VCC) in Gothenburg and carried out at Cross Design AB. The purpose of the project was to investigate how storage in the front part of the Volvo models S80, V70, XC70 and XC90 could be improved and optimised. The project should result in one storage solution concept. The procedure of the project was based on a combined methodology of the Sirius Masterplan Design Process and Systematic Problem Solving. To find the existing needs in car storage a survey was performed on a group of 20 car drivers who represented the target group of potential buyers. To make sure to receive extensive information both questionnaires, interviews and observations were carried out. In order to incorporate inspiration and an overview of the range of products on the market the team carried out a benchmarking of most of the leading car makes in Sweden. Related technologies were also studied to find new angles of approach and to increase the number of ideas. An analysis of how the car will be used in the future was performed as well as a general trend analysis of peoples life styles and habits. In the surveys it was found that people are spending more and more time in their cars and that it is becoming important to provide for other needs than the traditional. The studied cars are often used for longer trips at work or on vacation. This creates a need for possibilities for storing office equipment and to have easy access to beverage and food. The idea generation was carried out through the methods of brainstorming, categorising and and adjusted form of the Delphi method and resulted in a wide range of storing solutions. To narrow down the project it was decided to focus only on the glove compartment, the area in the middle of the dashboard, and on the area behind the centre stack. Several concepts were put together for each of these areas on the basis of the previously developed ideas. It was decided to proceed with the development of the glove compartment concepts. These were to be applied on the coming XC90 which has the largest glove compartment volume of VCC’s cars. The glove compartment concepts were compared to previously stated product demands and wishes as well as to each other. The ones with the most innovative ideas and best scores were extracted and supplemented with good ideas from other concepts. The selection specially focused on flexibility, organisation and individualisation possibilities as well as innovation. A combination of concepts ended up with a notch and a case concept, which both could be supplemented with a so called sleigh for easier access. Since both concepts and combinations lived up to the demands the final concept choice was based on calculated scores as well as which was considered to be the most innovative. On these grounds the case concept, called the Glove Compartment Case (GCC), was elected. The GCC consists of two removable cases: one cooling unit and one organised unit. The concept fulfils the wishes of flexibility, organisation and individuality since it allows the user to organise the glove compartment after occasion and stored items.

    Fulltekst (pdf)
    FULLTEXT01
  • 37. Aava, Kari
    et al.
    Olsson, Annicka
    Med vänskap i sagans värld: att nyttja sagan för att stärka vänskapsaspekten i värdegrunden samt för en ökad fantasi och kreativitet2003Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    FULLTEXT01
  • 38.
    Aava, Nils
    et al.
    Luleå tekniska universitet.
    Ericson, Ronald
    Luleå tekniska universitet.
    Esberg, Lars
    Luleå tekniska universitet.
    Belysning i bilverkstäder: förslag till belysningsplanering1979Rapport (Annet vitenskapelig)
  • 39. Aava, Pia
    et al.
    Vanhaniemi, Veronica
    Intressentdialog: en kartläggning utifrån GRI:s riktlinjer G32009Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    FULLTEXT01
  • 40.
    Abadei, S.
    et al.
    Department of Microelectronics, Chalmers University of Technology, Gothenburg, Sweden.
    Gevorgian, S
    Department of Microelectronics, Chalmers University of Technology, Gothenburg, Sweden;Core Unit Research Center, Ericsson Microwave Systems, Mölndal, Sweden.
    Cho, C.-R
    Department of Condensed Matter Physics, Royal Institute of Technology, Stockholm, Sweden.
    Grishin, A.
    Department of Condensed Matter Physics, Royal Institute of Technology, Stockholm, Sweden.
    Andreasson, Johanna
    Luleå tekniska universitet.
    Lindbäck, Ture
    Luleå tekniska universitet.
    DC field dependent properties of Na0.5 K0.5 NbO3/SiO2/Si structures at millimeter-wave frequencies2001Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 78, nr 13, s. 1900-1902Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dielectric properties of laser-ablated 0.5-μm-thick c-axis epitaxial Na0.5K0.5NbO3 films on high-resistivity (7.7 Ω cm) silicon SiO2/Si substrate are studied experimentally at frequencies up to 40 GHz. For measurements, planar 0.5-μm-thick gold electrodes (interdigital and straight slot) are photolithography defined on the top surface of Na0.5K0.5NbO3 films. The slot width between the electrodes is 2 or 4 μm. 13% capacitance change at 40 V dc bias and Q factor more than 15 are observed at 40 GHz, which makes the structure useful for applications in electrically tunable millimeter-wave devices

  • 41.
    Abadei, S.
    et al.
    Chalmers University of Technology, Department of Microelectronics.
    Gevorgian, S.
    Chalmers University of Technology, Department of Microelectronics.
    Kugler, V.
    Department of Physics, Linköping University.
    Helmersson, U.
    Department of Physics, Linköping University.
    Andreasson, Johanna
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Microwave properties of tunable capacitors basee on magnetron sputtered ferroelectric Na0.5K0.5NbO3 film on low and high resistivity silicon substrates2001Inngår i: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 39, nr 1-4, s. 359-366Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, small signal DC voltage dependent dielectric permittivity, loss tangent, and tuneability of magnetron sputtered epitaxial Na0.5K0.5NO3 films are studied experimentally. (100)-oriented Na0.5K0.5NbO3 films are deposited onto SiO2-buffered CMOS grade low resistivity (p = 10-20 cm) and high resistivity (p = 15-45 kcm) silicon substrates. Planar capacitors with 2 or 4 m gaps between electrodes have been fabricated on top of ferroelectric films. These devices have been characterized in the frequency range 1.0 MHz to 50 GHz at temperatures 30 - 300K. Na0.5K0.5NbO3/SiO2/Si structures on high resistivity silicon substrate exhibit C-V performances typical for Metal-Insulator- Semiconductor (MIS) capacitors. At low frequencies, f 1.0 GHz, the large tuneability and large losses are associated with the MIS structure, while at higher microwave frequencies the tuneability is mainly associated with the ferroelectric, film. At 1.0 MHz and room temperature, the tuneability of Na0.5K0.5NbO3/SiO2/Si structures more than 90%, reducing to 10-15 % at 50 GHz. The losses decrease with increasing the DC bias and frequency. A Q-factor more than 15 at 50 GHz is observed. The dielectric permittivity of the Na0.5K0.5NbO3 film is in the range 50-150 at frequencies 0.045-50 GHz. On low resistivity substrate the performance of Na0.5K0.5NbO3 films is completely screened by the high losses in silicon, and the tuneability is negligible

  • 42. Abakoumova, Natalia
    Modification of Silicalite-1 Membranes2005Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    In this work Silicalite-1 films were prepared on porous ?-alumina micro filtration filters acting as a support using the ”seed film method”. The films were modified using an aqueous solution of Ca(NO3)2 in order to obtain a carbon dioxide (CO2) selective membrane. Two different modification procedures were developed in the present work. The procedures are denoted “evacuation” and “spinning technique”. Single gas permeation and n-hexane porosimetry were used for the characterisation of the membranes. CO2, nitrogen (N2), helium (He) and hydrogen (H2) were used as probe molecules in single gas permeation experiments. n-Hexane porosimetry was used to determine the amount of defects in the membranes. Both modified and unmodified samples were characterized using these techniques. It was found that a high concentration of Ca(NO3)2 deteriorated the membrane quality according to porosimetry data. The CO2/(H2, N2 or He) permeance ratios became slightly higher after modification of samples modified with a lower salt concentration. However, no significant difference between the two modified methods could be observed with respect to CO2 selectivity. It may be thus concluded that CaO was not optimally deposited in the silicalite-1 film. EDS and SEM analysis showed the concentration of Ca varied on the surface but was distributed without aggregates.

    Fulltekst (pdf)
    FULLTEXT01
  • 43.
    Aban, Saman
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle.
    Principalansvaret för vårdnadshavare: Föräldrars skadeståndsansvar för skada vållad av barn2016Independent thesis Basic level (degree of Bachelor), 180 hpOppgave
    Abstract [sv]

    Personer under 15 år kan inte straffrättsligt bli ansvariga för brott de begått i enlighet med 1 kap 6§ BrB. Däremot kan en civilrättslig process gällande skadeståndsrättsligt anspråk bli aktuell i princip oberoende av skadevållarens ålder. Huvudregeln är alltså att barn kan bli skadeståndsskyldiga på samma sätt som en vuxen om de anses ha vållat skada. De större utmärkande skillnaderna mellan att hålla ett barn jämfört med en vuxen skadeståndsskyldig är att det görs en så kallad skälighetsbedömning när det gäller barn och även vid bedömning av barns culpa tar man mindre hänsyn till de subjektiva kriterierna. I denna uppsats utreds vårdnadshavarens ansvar enligt 3 kap. 5§ skadeståndslagen som infördes år 2010. Denna reglering innebär att föräldrar kan blir skadeståndsansvariga för skador som deras barn orsakar genom brott samt genom tillsynsansvaret som regleras i 6 kap. 2§ föräldrabalken. Denna paragraf reglerar att vårdnadshavaren skall ge barnet den tillsyn och uppsikt det behöver medhänsyn till ålder, utveckling och övriga omständigheter för att hindra skadevållande handlingar. Skillnaden mellan dessa respektive lagregler gällande att vårdnadshavaren skall anses vara skadeståndsansvarig är att den förra förutsätter att barnet begått ett brott och förutsätter heller ej culpa medan den senare inte gör det.

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  • 44.
    Abaray, Lahcen
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Development and Characterization Of Ceramic Particles Reinforced Metal Matrix Composites2023Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Wear is a significant challenge encountered in the mining industry, affecting the durability and performance of materials. Hadfield steel has emerged as a commonly used material in this field due to its favorable properties. However, there is a persistent need to enhance its service life. Metal matrix composites (MMCs) offer a potential solution to address this issue. By reinforcingHadfield steel with ceramic particles, MMCs aim to improve the material's wear resistance and extend its operational lifespan. This study specifically investigates the potential of MMCs, reinforced with Zirconia Toughened Alumina (ZTA) particles, to enhance the performance of Hadfield steel in mining applications. Notably, ZTA particles are chosen for their exceptional wear resistance and low cost, making them an attractive reinforcement option. The mechanical behavior and properties of ZTA particle reinforced metal matrix composites (MMCs) were thoroughly investigated by conducting a comprehensive analysis. This analysis encompassed adetailed examination of the microstructure, composition, distribution, as well as the bonding between ZTA particles and the metallic matrix, along with rigorous measurements of hardness and wear resistance. The findings of the study reveal that the ZTA particle reinforced MMCs exhibit a uniform dispersion of ZTA particles throughout the composite material. This homogeneous distribution contributes to notable enhancements in the average hardness of the MMCs, surpassing that of Hadfield steel alone. However, the study did not observe a substantial enhancement in the wear resistance of the material.

  • 45.
    Abarkan, Abdellah
    et al.
    Blekinge tekniska högskola, Karlskrona, Sverige.
    Rizzo, Agatino
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Öjehag-Pettersson, Andreas
    Karlstads universitet, Karlstad, Sverige.
    Byerley, Andrew
    Stockholms universitet, Stockholm, Sverige.
    Karvonen, Andy
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Legby, Ann
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Braide, Anna
    Chalmers tekniska högskola, Göteborg, Sverige.
    Hellström, Björn
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Christophers, Brett
    Uppsala Universitet, Uppsala, Sverige.
    Johansson, Britt-Marie
    Lunds universitet, Lund, Sverige.
    Yigit Turan, Burcu
    Sveriges lantbruksuniversitet, Uppsala, Sverige.
    Listerborn, Carina
    Malmö universitet, Malmö, Sverige.
    Dyrssen, Catharina
    Chalmers tekniska högskola, Göteborg, Sverige.
    Gabrielsson, Catharina
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Thörn, Catharina
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Mukhtar-Landgren, Dalia
    Lunds universitet, Lund, Sverige.
    Koch, Daniel
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Polanska, Dominika V
    Uppsala universitet, Uppsala, Sverige.
    Högström, Ebba
    Blekinge tekniska högskola, Karlskrona, Sverige.
    Nilsson, Emma
    Lunds universitet, Lund, Sverige.
    Clark, Eric
    Lunds universitet, Lund, Sverige.
    Stenberg, Erik
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Andersson, Eva
    Stockholms universitet, Stockholm, Sverige.
    Berggård, Glenn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Henriksson, Greger
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Lindholm, Gunilla
    Sveriges lantbruksuniversitet, Uppsala, Sverige.
    Sandin, Gunnar
    Lunds universitet, Lund, Sverige.
    Forsberg, Gunnel
    Stockholms universitet, Stockholm, Sverige.
    Baeten, Guy
    Malmö universitet, Malmö, Sverige.
    Cars, Göran
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Rohracher, Harald
    Linköpings universitet, Linköping, Sverige.
    Westlund, Hans
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Mattsson, Helena
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Frichot, Hélène
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Palmer, Henrietta
    Chalmers tekniska högskola, Göteborg, Sverige.
    Corvellec, Hervé
    Lunds universitet, Lund, Sverige.
    Thörn, Håkan
    Göteborgs universitet, Göteborg, Sverige.
    Sandström, Ida
    Lunds universitet, Lund, Sverige.
    Lindell, Ilda
    Stockholms universitet, Stockholm, Sverige.
    Werner, Inga Britt
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Molina, Irene
    Uppsala universitet, Uppsala, Sverige.
    Mack, Jennifer
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Stenberg, Jenny
    Chalmers tekniska högskola, Göteborg, Sverige.
    Magnusson, Jesper
    Lunds universitet, Lund, Sweden.
    Metzger, Jonathan
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Wangel, Josefin
    Sveriges lantbruksuniversitet, Uppsala, Sverige.
    Fredriksson, Julia
    Chalmers tekniska högskola, Göteborg, Sverige.
    Bradley, Karin
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Grundström, Karin
    Malmö universitet, Malmö, Sverige.
    Nylund, Katarina
    Malmö universitet, Malmö, Sverige.
    Grange, Kristina
    Chalmers tekniska högskola, Göteborg, Sverige.
    Nilsson, Kristina L.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Ståhl, Lars-Henrik
    Lunds universitet, Lund, Sverige.
    Olsson, Lina
    Malmö universitet, Malmö, Sverige.
    Soneryd, Linda
    Göteborgs universitet, Göteborg, Sverige.
    Smas, Lukas
    Stockholms universitet, Stockholm, Sverige.
    Hellström Reimer, Maria
    Malmö universitet, Malmö, Sverige.
    Håkansson, Maria
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Zapata Campos, María José
    Göteborgs universitet, Göteborg, Sverige.
    Franzén, Mats
    Uppsala universitet, Uppsala, Sverige.
    Kärrholm, Mattias
    Lunds universitet, Lund, Sverige.
    Qviström, Mattias
    Sveriges lantbruksuniversitet, Uppsala, Sverige.
    Schalk, Meike
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Tesfahuney, Mekonnen
    Karlstads universitet, Karlstad, Sverige.
    Tahvilzadeh, Nazem
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Björling, Nils
    Chalmers tekniska högskola, Göteborg, Sverige.
    Nylander, Ola
    Chalmers tekniska högskola, Göteborg, Sverige.
    Zapata, Patrik
    Göteborgs universitet, Göteborg, Sverige.
    Femenías, Paula
    Chalmers tekniska högskola, Göteborg, Sverige.
    Hagbert, Pernilla
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Schmitt, Peter
    Stockholms universitet, Stockholm, Sverige.
    Ek, Richard
    Lunds universitet, Lund, Sverige.
    Andersson, Roger
    Uppsala universitet, Uppsala, Sverige.
    Johansson, Rolf
    Sveriges lantbruksuniversitet, Uppsala, Sverige.
    Kopljar, Sandra
    Lunds universitet, Lund, Sverige.
    Borgström, Sara
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Brorström, Sara
    Göteborgs universitet, Göteborg, Sverige.
    Schmidt, Staffan
    Malmö universitet, Malmö, Sverige.
    Gromark, Sten
    Chalmers tekniska högskola, Göteborg, Sverige.
    Westerdahl, Stig
    Malmö universitet, Malmö, Sverige.
    Holgersen, Ståle
    Uppsala Universitet, Uppsala, Sverige.
    Urban, Susanne
    Uppsala Universitet, Uppsala, Sverige.
    Salonen, Tapio
    Malmö universitet, Malmö, Sverige.
    Borén, Thomas
    Stockholms universitet, Stockholm, Sverige.
    Haas, Tigran
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Glad, Wiktoria
    Linköpings universitet, Linköping, Sverige.
    Svane, Örjan
    Kungliga tekniska högskolan, Stockholm, Sverige.
    Lyssna på forskningen: Den visar på avregleringens problem2019Inngår i: Dagens nyheter, ISSN 1101-2447, nr 10/21/2019Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Fulltekst (pdf)
    fulltext
  • 46.
    Abb, Marcel J. S.
    et al.
    Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany; Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany.
    Weber, Tim
    Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany; Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany.
    Langsdorf, Daniel
    Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany; Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany.
    Koller, Volkmar
    Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany; Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany.
    Gericke, Sabrina M.
    Combustion Physics, Lund University, Box 118, S-22100 Lund, Sweden.
    Pfaff, Sebastian
    Combustion Physics, Lund University, Box 118, S-22100 Lund, Sweden.
    Busch, Michael
    Division Chemical Physics Department of Physics and Competence Centre for Catalysis, Chalmersplatsen 4, SE-41296 Göteborg, Sweden.
    Zetterberg, Johan
    Combustion Physics, Lund University, Box 118, S-22100 Lund, Sweden.
    Preobrajenski, Alexei
    MAX IV Laboratory, E120057, Fontongatan 2, 22484 Lund, Sweden.
    Grönbeck, Henrik
    Division Chemical Physics Department of Physics and Competence Centre for Catalysis, Chalmersplatsen 4, SE-41296 Göteborg, Sweden.
    Lundgren, Edvin
    Synchrotron Radiation Research, Lund University, Box 118, S-22100 Lund, Sweden.
    Over, Herbert
    Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany; Center for Materials Research, Justus Liebig University, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany.
    Thermal Stability of Single-Crystalline IrO2(110) Layers: Spectroscopic and Adsorption Studies2020Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 124, nr 28, s. 15324-15336Artikkel i tidsskrift (Fagfellevurdert)
  • 47.
    Abba, Alia Besma
    et al.
    Laboratory of Water and Environment Engineering in Saharan Environment, University of Ouargla, PB 147 RP, Ouargla 30000, Algeria.
    Saggai, Sofiane
    Laboratory of Water and Environment Engineering in Saharan Environment, University of Ouargla, PB 147 RP, Ouargla 30000, Algeria.
    Touil, Youcef
    Laboratory of Biogeochemical of Desert Environment, University of Ouargla, PB 147 RP, Ouargla 30000, Algeria.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Kouadri, Saber
    Laboratory of Water and Environment Engineering in Saharan Environment, University of Ouargla, PB 147 RP, Ouargla 30000, Algeria.
    Nouasria, Fatima Zohra
    Dynamic Interactions and Reactivity of Systems, University of Ouargla, PB 147 RP, Ouargla 30000, Algeria.
    Najm, Hadee Mohammed
    Department of Civil Engineering, Zakir Husain Engineering College, Aligarh Muslim University, Aligarh 202002, India.
    Mashaan, Nuha S.
    Faculty of Science and Engineering, School of Civil and Mechanical Engineering, Curtin University, Bentley, WA 6102, Australia.
    Eldirderi, Moutaz Mustafa A.
    Department of Chemical Engineering, College of Engineering, King Khalid University, Abha 61421, Saudi Arabia.
    Khedher, Khaled Mohamed
    Department of Civil Engineering, College of Engineering, King Khalid University, Abha 61421, Saudi Arabia; Department of Civil Engineering, High Institute of Technological Studies, Mrezgua University Campus, Nabeul 8000, Tunisia.
    Copper and Zinc Removal from Wastewater Using Alum Sludge Recovered from Water Treatment Plant2022Inngår i: Sustainability, E-ISSN 2071-1050, Vol. 14, nr 16, artikkel-id 9806Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The study aimed to determine Aluminum sludge composition and structure for its valorisation as an alternative natural material for heavy metals removal from wastewater for further reuse as treated water in different applications. The study was conducted to investigate the introduction of Al-bearing sludge composition. The physical and chemical properties were examined using X-ray diffraction tests (XRD), scanning electron microscope tests (SEM), Fourier-transform infrared tests (FTIR), and Brunauer-Emmett-Teller tests (BET). Furthermore, the heavy metal concentrations of synthetic wastewater were measured using the spectrophotometry method. The experimental procedure is based on testing different pH limits and amounts of aluminum sludge to find the optimum conditions for copper (Cu) and zinc (Zn) removal. The results demonstrated a high removal efficiency where its value reached up to 97.4% and 96.6% for Zn and Cu, respectively, in an acidic medium (pH = 6) using a relatively high amount of sludge (1400 mg). Nevertheless, a low efficiency was obtained in the strongly acidic medium (pH = 4) and a smaller sludge amount of about 480 mg.

  • 48.
    Abba, S. I.
    et al.
    Department of Civil Engineering, Faculty of Engineering, Baze University, Abuja, Nigeria.
    Abdulkadir, R. A.
    Department of Electrical Engineering, Kano University of Science and Technology, Wudil, Nigeria.
    Gaya, M. S.
    Department of Electrical Engineering, Kano University of Science and Technology, Wudil, Nigeria.
    Sammen, Saad Sh.
    Department of Civil Engineering, College of Engineering, University of Diyala, Diyala Governorate, Iraq.
    Ghali, Umar
    Department of Medical Biochemistry, Faculty of Medicine, Near East University, Mersin-10, Nicosia, North Cyprus, 99138, Turkey.
    Nawaila, M. B.
    Department of Computer Science Education, Aminu Saleh College of Education, Azare, Nigeria.
    Oğuz, Gözde
    Department of Electrical and Electronic Engineering, Faculty of Civil and Environmental Engineering, Near East University, Mersin 10, Nicosia, North Cyprus, Turkey.
    Malik, Anurag
    Punjab Agricultural University, Regional Research Station, Bathinda, Punjab, 151001, India.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Effluents quality prediction by using nonlinear dynamic block-oriented models: A system identification approach2021Inngår i: Desalination and Water Treatment, ISSN 1944-3994, E-ISSN 1944-3986, Vol. 218, s. 52-62Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dynamic and complex municipal wastewater treatment plant (MWWTP) process should be handled efficiently to safeguard the excellent quality of effluents characteristics. Most of the available mathematical models do not efficiently capture the MWWTP process, in such cases, the data-driven models are reliable and indispensable for effective modeling of effluents characteristics. In the present research, two nonlinear system identification (NSI) models namely; Hammerstein-Wiener model (HW) and nonlinear autoregressive with exogenous (NARX) neural network model, and a classical autoregressive (AR) model were proposed to predict the characteristics of the effluent of total suspended solids (TSSeff) and pHeff from Nicosia MWWTP in Cyprus. In order to attain the optimal models, two different combinations of input variables were cast through auto-correla-tion function and partial auto-correlation analysis. The prediction accuracy was evaluated using three statistical indicators the determination coefficient (DC), root mean square error (RMSE) and correlation coefficient (CC). The results of the appraisal indicated that the HW model outperformed NARX and AR models in predicting the pHeff, while the NARX model performed better than the HW and AR models for TSSeff prediction. It was evident that the accuracy of the HW increased averagely up to 18% with regards to the NARX model for pHeff . Likewise, the TSSeff performance increased averagely up to 25% with regards to the HW model. Also, in the validation phase, the HW model yielded DC, RMSE, and CC of 0.7355, 0.1071, and 0.8578 for pHeff, while the NARX model yielded 0.9804, 0.0049 and 0.9902 for TSSeff, respectively. For comparison with the traditional AR, the results showed that both HW and NARX models outperformed in (TSSeff) and pHeff prediction at the study location. Hence, the outcomes determined that the NSI model (i.e., HW and NARX) are reliable and resilient modeling tools that could be adopted for pHeff and TSSeff prediction.

    Fulltekst (pdf)
    fulltext
  • 49.
    Abba, S.I.
    et al.
    Faculty of Engineering, Department of Civil Engineering, Baze University, Abuja, Nigeria; Interdisciplinary Research Center for Membrane and Water Security, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia.
    Abdulkadir, R.A.
    Department of Electrical Engineering, Kano University of Science and Technology, Wudil, Nigeria.
    Sammen, Saad Sh.
    Department of Civil Engineering, College of Engineering, University of Diyala, Diyala Governorate, Iraq.
    Pham, Quoc Bao
    Faculty of Natural Sciences, Institute of Earth Sciences, University of Silesia in Katowice, Będzińska street 60, 41-200, Sosnowiec, Poland.
    Lawan, A.A.
    Department of Computer Science, Kano University of Science and Technology, Wudil, Nigeria.
    Esmaili, Parvaneh
    Department of Electrical and Electronic Engineering Near East University, Nicosia, North Cyprus, Turkey.
    Malik, Anurag
    Punjab Agricultural University, Regional Research Station, Bathinda 151001, Punjab, India.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Integrating feature extraction approaches with hybrid emotional neural networks for water quality index modeling2022Inngår i: Applied Soft Computing, ISSN 1568-4946, E-ISSN 1872-9681, Vol. 114, artikkel-id 108036Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The establishment of water quality prediction models is vital for aquatic ecosystems analysis. The traditional methods of water quality index (WQI) analysis are time-consuming and associated with a high degree of errors. These days, the application of artificial intelligence (AI) based models are trending for capturing nonlinear and complex processes. Therefore, the present study was conducted to predict the WQI in the Kinta River, Malaysia by employing the hybrid AI model i.e., GA-EANN (genetic algorithm-emotional artificial neural network). The extreme gradient boosting (XGB) and neuro-sensitivity analysis (NSA) approaches were utilized for feature extraction, and six different model combinations were derived to examine the relationship among the WQI with water quality (WQ) variables. The efficacy of the proposed hybrid GA-EANN model was evaluated against the backpropagation neural network (BPNN) and multilinear regression (MLR) models during calibration, and validation periods based on Nash–Sutcliffeefficiency (NSE), mean square error (MSE), root mean square error (RMSE), mean absolute percentage error (MAPE), and correlation coefficient (CC) indicators. According to results of appraisal the hybrid GA-EANN model produced better outcomes (NSE = 0.9233/ 0.9018, MSE = 10.5195/ 9.7889 mg/L, RMSE = 3.2434/ 3.1287 mg/L, MAPE = 3.8032/ 3.0348 mg/L, CC = 0.9609/ 0.9496) in calibration/ validation phases than BPNN and MLR models. In addition, the results indicate the better performance and suitability of the hybrid GA-EANN model with five input parameters in predicting the WQI for the study site.

    Fulltekst (pdf)
    fulltext
  • 50.
    Abbas, Ghulam
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Johansson, Gustav
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Alay-e-Abbas, Syed Muhammad
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Computational Materials Modeling Laboratory, Department of Physics, Government College University, Faisalabad 38040, Pakistan.
    Shi, Yijun
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Larsson, J. Andreas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Quasi Three-Dimensional Tetragonal SiC Polymorphs as Efficient Anodes for Sodium-Ion Batteries2023Inngår i: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 6, nr 17, s. 8976-8988Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present work, we investigate, for the first time, quasi 3D porous tetragonal silicon–carbon polymorphs t(SiC)12 and t(SiC)20 on the basis of first-principles density functional theory calculations. The structural design of these q3-t(SiC)12 and q3-t(SiC)20 polymorphs follows an intuitive rational approach based on armchair nanotubes of a tetragonal SiC monolayer where C–C and Si–Si bonds are arranged in a paired configuration for retaining a 1:1 ratio of the two elements. Our calculations uncover that q3-t(SiC)12 and q3-t(SiC)20 polymorphs are thermally, dynamically, and mechanically stable with this lattice framework. The results demonstrate that the smaller polymorph q3-t(SiC)12 shows a small band gap (∼0.59 eV), while the larger polymorph of q3-t(SiC)20 displays a Dirac nodal line semimetal. Moreover, the 1D channels are favorable for accommodating Na ions with excellent (>300 mAh g–1) reversible theoretical capacities. Thus confirming potential suitability of the two porous polymorphs with an appropriate average voltage and vanishingly small volume change (<6%) as anodes for Na-ion batteries.

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    fulltext
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