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  • 301.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Alsyouf, Imad
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Ingwald, Anders
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Model for selecting the most cost-effective maintenance approach2005In: Creation of Industrial Competitiveness: CIC 2001-2004 / [ed] Basim Al-Najjar ; Anders Pehrsson, Växjö: Växjö University Press , 2005, p. 59-74Chapter in book (Other academic)
  • 302.
    Al-Najjar, Basim
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Alsyouf, Imad
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Ingwald, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Selecting and Improving the most Cost-effective Maintenance Policy: A Model2004Conference paper (Refereed)
  • 303.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Alsyouf, Imad
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Prakash, Om
    The impact of internal effectiveness on company competitiveness & profitability2005In: Creation on industrial Competitivness: CIC 2001-2004 / [ed] Basim Al-Najjar ; Anders Pehrsson, Växjö: Växjö University Press , 2005, p. 17-27Chapter in book (Other academic)
  • 304.
    Al-Najjar, Basim
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Alsyouf, Imad
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Salgado, E.
    Khoshaba, Samir
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Faaborg, K.
    The economic importance of maintenance planning when using vibration-based maintenance2001Report (Other academic)
  • 305.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Andersson, Daniel
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Jacobsson, Martin
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    A Model to Describe the Relationships Man–Machine–Maintenance–Economy (MMME)2007In: IMECS 2007: International Multiconference of Engineers and Computer Scientists, 2007, Vol. II, p. 2127-2132p. 2127-2132Chapter in book (Refereed)
    Abstract [en]

    In the globalisation spirit, one of the major objectives of companies is how to reduce the production losses cost-effectively for continuously enhancement of competitiveness and profitability. However, this area has been neglected by scientists and not given the attention justified considering its obvious link to company profitability. To fill this gap, better understanding of the relations and interactions between man, machine/production process, maintenance and economy is vital. Also, it is important for identifying and eliminating root causes of the losses. In this paper, we develop a model to describe these interactions using the most relevant factors, such as maintenance organisation, personnel commitment, machine condition and characteristics, and the impact of maintenance performance on production time. The use of the model and its potential benefits are tested using an application example. This example illustrates how the above mentioned factors affect the production time and is thereafter derived to financial results. The result is accordingly a model that can help all producing companies categorise the causes behind losses and identify where losses arise and where to focus their work of continuous cost-effective improvements.

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  • 306.
    Al-Najjar, Basim
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Ciganovic, Renato
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    A Model for More Accurate Maintenance Decisions2010In: Engineering Asset Management: Proceeding of the Fourth World Congress on Engineering Asset Management (WCEAM) 2009 / [ed] Dimitris Kiritsis, Christos Emmanouilidis, Andy Koronios, and Joseph Mathew, Springer, 2010, p. 7-14Conference paper (Refereed)
    Abstract [en]

    It is usual when using CM technology for assessing the state of a component and planning maintenance actions using predetermined levels for warnings and replacements. The replacement of a damaged component is usually done at lower or higher than the predetermined level, which both means losses. This is because the probability of doing replacements just at the predetermined level is negligibly small. The accuracy in the assessment of the condition of a component has big technical and economic impact on the output of the machine, production process and consequently company profitability and competitiveness. The higher the accuracy in assessing the condition of a component yields higher probability of avoiding failures and planning maintenance actions at low costs. In this paper, techniques for assessing the state of a component using both mechanistic and other statistical approaches are considered. This paper also applies Cumulative Sum (CUSUM) Chart for identifying the time of damage initiation and reducing false alarms.  Techniques for assessing the probability of failure of a component and its residual life, and predicting the vibration level at the next planned measuring opportunity or planned stoppage are introduced, discussed, computerised and tested. The problem addressed is: How is it possible to increase the accuracy of assessing the condition of a component? The major result achieved is; development of a model for more accurate assessment of the condition of a component/equipment through combining different approaches. The main conclusion that can be drawn is; applying the model, it is possible to enhance the accuracy of assessment of the condition of a component/equipment and consequently maintenance decision since the integrated model provides comprehensive and relevant information in one platform.

  • 307.
    Al-Najjar, Basim
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Eberhagen, Niclas
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Dynamic and Cost-effective Maintenance Decisions2010In: E-maintenance / [ed] Kenneth Holmberg, London: Springer, 2010, 1, p. 345-390Chapter in book (Refereed)
    Abstract [en]

    In general, all the elements involved in a production process, such as tools, machinery, methods, competence and working environment are exposed to changes. Thus, to maintain and improve company profitability and competitiveness, it is necessary to reduce losses through maintaining and improving the quality of the elements involved in the production process. Therefore, the maintenance strategy applied should be dynamic to be suited for all these changes cost-effectively. In producing companies, the accuracy of maintenance decisions is essential for reducing economic losses generated due to unnecessary stoppages in companies of intensive capital investment where stoppage time is expensive, especially in paper and pulp mills, refineries, power stations and engineering manufacturing. Therefore, it is necessary for maintenance and production managers to have a system providing the data required to achieve dynamic and cost-effective maintenance decisions.

    In this chapter, the new maintenance decision support system (MDSS) for achieving dynamic and cost-effective maintenance decisions developed in Chapter 12 is tested and discussed. The developed system is MIMOSA compatible, consists of three toolsets and five software modules for performing six services to achieve different objectives, e.g.:

    1. higher accuracy of maintenance decisions;

    2. selection of the most cost-effective maintenance solutions;

    3. identification and prioritisation of problem areas and assessment of losses in production time; and

    4. mapping, follow up and assessment of maintenance cost-effectiveness (maintenance savings and profit) to achieve continuous and cost effective improvement.

  • 308.
    Al-Najjar, Basim
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Faaborg, Kenneth
    Ingwald, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Effektivare underhåll när rätt åtgärd görs i rätt tid2010In: Husbyggaren, no 3, p. 20-22Article in journal (Other (popular science, discussion, etc.))
  • 309.
    Al-Najjar, Basim
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Hailemariam, Matias
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Maintenance Solutions for Continuous & Cost-effective Improvement of Wind Turbine Performance2012In: Workshop on Advanced Maintenance Engineering, Services and Technology (A-Mest'12), 2012Conference paper (Refereed)
    Abstract [en]

    Enhancement of company competitiveness and profitability demands continuous, high quality and trouble free production. Technical specifications and the condition of a wind turbine depend on the quality and condition of its significant components, which usually have the biggest impact on production continuity, - cost per KW and the environment. These necessitate intelligent technologies for maintaining the quality of significant components. Thus, it would be mandatory to select the most informative condition monitoring (CM) system and most cost-effective maintenance policy. In this paper, wind turbine problems are specified and described, available maintenance and CM techniques are discussed, and a maintenance solution with clearly specified objectives are suggested, discussed and the potential results are outlined in the end.

     

  • 310.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Hansson, Mats-Ola
    WM-Data Ellips.
    Sunnegård, Patrik
    Aerotech Telub.
    Benchmarking of Maintenance Performance: a Case Study in Two Manufacturers of Furniture2004In: IMA Journal of Management Mathematics, ISSN 1471-678X, E-ISSN 1471-6798, Vol. 15, no 3, p. 253-270Article in journal (Refereed)
    Abstract [en]

    When profit margins of a plant are decreasing then, the need for reliable and efficient maintenance policy becomes more important. Measuring maintenance performance is important for companies to recognise whether their planned goals are achieved or not. Also, such measurements can be utilised for benchmarking, which is one of the tools for never-ending improvement. But, these objectives cannot be achieved without well-documented data of the relevant variables. Better data coverage and quality is necessary for following maintenance performance development and it would, in many cases, clarify the ambiguity concerning the main problem in the context, namely that neither the production nor maintenance department can show what effect maintenance has on profitability.

    A more effective maintenance policy indirectly implies improvements in product quality and manufacturing process effectiveness. Elongation of the production time, i.e. reducing the down time due to failures, planned replacements and repair, in addition to the improvement in the total maintenance activities, are also some of the results that can be expected when an efficient maintenance policy is used. Measuring and monitoring maintenance performance measures is required partly for detecting, and eventually treating as soon as possible, undesirable changes and partly to make benchmarking with the best in the branch, which saves appreciable economic losses for companies.

    In this paper, a model for how to identify the measurable variables, which are needed to develop measures for monitoring maintenance performance behaviour systematically, is developed. Five maintenance performance measures are proposed and applied. An additional model for systematically analysing the trend of maintenance performance measures, for an overall assessment of the company’s situation, is presented. Two case studies in manufacturers of furniture are conducted to verify these models.

  • 311.
    Al-Najjar, Basim
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Hansson, M-O
    Sunnegårdh, P.
    Benchmarking of maintenance performance: A case study in two manufacturers of furniture2001Conference paper (Refereed)
  • 312.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Ingwald, Anders
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Identification, analysis, elimination and prevention of problems: method and concepts2002In: Proceedings IFRIMmmm : maintenance management & modelling conference, Växjö, Sweden, 6-8th May 2002, 2002Conference paper (Refereed)
  • 313.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Ingwald, Anders
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Identification, analysis, elimination and prevention of recurrence of problems: Methods and concepts2004In: Proceedings of MIMAR 2004 - 5th IMA International Conference on Modelling in industrial maintenance and reliability: Impact on practice, 2004, p. 13-20Conference paper (Refereed)
  • 314.
    Al-Najjar, Basim
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Ingwald, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Kans, Mirka
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    A database model for monitoring and assessing technical and financial impacts of maintenance on the production process2004Conference paper (Refereed)
  • 315.
    Al-Najjar, Basim
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Ingwald, Anders
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Kans, Mirka
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Maintenance in Real Estate and Manufacturing Industries: Differences, Problems, Needs and Potentials - Four Case Studies2016In: Proceedings of the 10th World Congress on Engineering Asset Management (WCEAM 2015) / [ed] Koskinen, KT; Kortelainen, H; Aaltonen, J; Uusitalo, T; Komonen, K; Mathew, J; Laitinen, J, Switzerland: Springer, 2016, p. 13-27Conference paper (Refereed)
    Abstract [en]

    It is about 50 % of the activities in the housing sector in the EU region are related to maintenance. According to several publications, building management systems are still quite rare and efficient methodologies for service life prediction of building parts still need to be developed. Also, recent studies show difficulties in finding comprehensive answers concerning, e.g. identifying risks and preventive maintenance actions. Incomplete information can easily lead to incorrect maintenance actions. The problem addressed is: How to improve performance and cost-effectiveness of the maintenance applied on real estate facilities especially buildings to reduce maintenance and management costs and increase company profit? The study’s objectives are to analyse maintenance; techniques, costs, weaknesses and potentials, and compare it with manufacturing industry experience. Also, to investigate whether there is a need for a DSS for planning and follow up cost-effective CBM. The major results of four case studies are; (1) Preventive and breakdown maintenance are mainly used and actions are funded from different accounts. (2) The concept of cost-effectiveness is applied occasionally. (3) Lack of CBM-DSS for planning, follow up and evaluate maintenance profitability, and cost-effective improvements of company business and tenant living quality. (4) The profit generated by continuous heating of building thanks efficient maintenance is about 2.332 million SEK. The major conclusion; there is a reasonable opportunity to reduce buildings’ management and maintenance costs.

  • 316.
    Al-Najjar, Basim
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Jacobsson, Martin
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology. LNU.
    A computerised model to enhance the cost-effectiveness of production and maintenance dynamic decisions: A case study at Fiat2013In: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 19, no 2, p. 114-127Article in journal (Refereed)
    Abstract [en]

    Purpose:

    – To develop and test a model and software-based support system for better understanding

    of the interactions between man-machine-maintenance-economy (MMME), and enable cost-effective decisions.

    Design/methodology/approach:

    – The study is based on published knowledge and experience within maintenance, maintenance organization and production, and a case study.

    Findings:

    – Development of a model describing interactions between man-machine-maintenance-economy interactions and MMME software module. MMME test shows its ability to identify, quantify, assess and follow up losses in production time which is necessary when planning effective maintenance actions.

    Research limitations/implications:

    – In the paper the focus is to quantify production time losses in order to identify the root causes of the problem. The case study is performed at a manufacturing plant for truck engines.

    Practical implications:

    – A systematic approach of how to quantify and evaluate losses in production time in order to identify problems and problem areas within the production. This approach is discussed and motivated with the aim of achieving more cost-effective decisions in maintenance.

    Originality/value:

    – The model and software application developed enables a structured way of analyzing production time losses in order to find cost-effective solutions to the problems. The model is very flexible enabling it to be customized for a wide spectrum of branches.

     

  • 317.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Johansson, B.
    Nord, C.
    Rundqvist, T.
    Styr produktens kvalitet genom att styra maskinens tillstånd1999Report (Other academic)
  • 318.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Kans, Mirka
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    A Model to Identify Relevant Data for Accurate Problem Tracing and Localisation, and Cost-effective Decisions: A Case Study2006In: Proceedings of the First International Conference on Maintenance Engineering ICME 2006 New Century New Maintenance / [ed] Jia Xisheng et al., 2006, , p. 14-21Conference paper (Refereed)
    Abstract [en]

    Mapping the technical and financial effectiveness of a production is crucial for making cost-effective maintenance decisions. But, a successful mapping cannot be achieved without a well-structured database including all relevant data required for this task. The problem addressed in this paper is how to identify the relevant variables and performance measures that should be monitored for achieving cost-effective maintenance decisions that enhance company’s business? The main result achieved is a model for identifying relevant data required for accurate problem tracing and localisation within maintenance and production processes using a top down approach. The potential of applying the model is examined in a case study including databases of two commercial software programs developed for maintenance. The main conclusions are integration of IT and data resources within the enterprise is needed for developing a holistic view of the production process and a well-formulated and documented procedure of data identification will ensure that the data can be traced back to root sources and in this way we can support the work of continuous cost-effective improvement by eliminating root causes of problems at an early stage.

    Download full text (pdf)
    fulltext
  • 319.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Kans, Mirka
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Systemekonomi.
    A model to identify relevant data for problem tracing and maintenance cost-effective decisions: a case study2006In: International Journal of Productivity and Performance Management, ISSN 1741-0401, E-ISSN 1758-6658, Vol. 55, no 8, p. 616-637Article in journal (Refereed)
    Abstract [en]

    Purpose – The purpose of this paper is to help build up a relevant database for mapping technicaland financial effectiveness of production in order to make cost-effective maintenance decisions.Design/methodology/approach – A theoretical model is developed based on past research andexperience adopting a holistic systems approach on the production. A case study, which includesdatabases of two maintenance-used software programs, verifies the potential of applying the model.Findings – The main result achieved is a model for identifying relevant data required for accurateproblem tracing and localisation within maintenance and production processes using a top downapproach. The main conclusions are integration of IT and data resources within the enterprise isneeded for developing a holistic view of the production process and a well-formulated and documentedprocedure of data identification will ensure that the data can be traced back to root sources and in thisway we can support the work of continuous cost-effective improvement by eliminating root causes ofproblems at an early stage.Research limitations/implications – Further model verification by industrial case studies wouldbe of interest.Practical implications – The holistic approach and the model presented are applicable especially incapital intensive industries, where maintenance budget is not negligible and the amount of data toprocess is large. By structuring the data need and data identification process relevant performancemeasures will be monitored and advanced maintenance concepts can be applied.Originality/value – By applying the proposed model in industry, the data identification processitself and not the data contents is necessary to be standardised and structured. It shifts the focus of thequality aspect from just data level to both data and data collection level. The performance measureswill therefore not be chosen depending on what the IT applications can provide in first hand, but uponwhat is needed for cost-effective mapping, analysis, following up and assessment of maintenanceperformance.

  • 320.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Kans, Mirka
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Ingwald, Anders
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    BETUS: a maintenance decision support system2005In: Creation of Industrial Competitiveness: CIC 2001-2004 / [ed] Basim Al-Najjar ; Anders Pehrsson, Växjö: Växjö University Press , 2005, p. 41-57Chapter in book (Other academic)
  • 321.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Kans, Mirka
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Ingwald, Anders
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Samadi, R.
    Decision support system for monitoring and assessing maintenance financial impact on company´s profitability2003In: First International Conference on Performance Measures, Benchmarking and Best Practices in New Economy, Business Excellence 2003, June 10-13, Guimaraes, Portugal., 2003, p. 79-86Conference paper (Refereed)
  • 322.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Krantz, M.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Kans, Mirka
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Maintenance costs, savings and benefits in manufacturing2002In: Proceedings of the 4th international conference on quality, reliability and maintenance / [ed] McNulty, GJ, 2002, p. 7-10Conference paper (Refereed)
    Abstract [en]

    More efficient maintenance yields in increased production, lower costs and higher product quality promoting company's business. Data will be used in a Decision Support System (DSS) to achieve cost-effective decisions, improve maintenance strategy and increase company's profit. In this paper, an Information Technology (IT) System, i.e. GMDSS, supporting the concept of total quality maintenance (TQMain) is developed. This system consists of a Database Management System (DBMS), DSS and the interaction between these components and between the system and it's environment. The system is verified in real data from a Swedish paper mill. The major results are maintenance direct costs, savings and benefits are considered instead of direct and indirect maintenance costs. Economic losses are considered as potential savings when a more efficient maintenance is used. Further, vibration-based maintenance (VBM) saved annually about 4 MSEK. It is about nine times the investments done in maintenance. which were between 1-2.2% of the total potential savings. The mean conclusion of this study is using this methodology for assessing maintenance economic role, it would be classified as a profit-centre.

  • 323.
    Al-Najjar, Basim
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Kumar, U.
    Effectiveness of vibration-based monitoring systems in paper mills: Two case studies1997In: COMADEM '97: 10th international congress and exhibition on condition monitoring and diagnostic engineering management, vol. 1 / [ed] Jantunen, E; Holmberg, K; Rao, RBK, 1997, p. 48-57Conference paper (Refereed)
    Abstract [en]

    The effectiveness of vibration-based monitoring, (VBM), system may be measured in terms of reduced stoppage rates and increased use of potential bearing life. Analysis of data from roller bearings at two paper mills suggests that greater bearing lives can be safely achieved by increasing the accuracy of the vibration data, This paper relates bearing failures to the observed vibration spectra and their development over the bearings' lives. The literature was found mainly to confirm the author's analysis. A systematic approach which describes the performance and objectives of the studies is discussed. Explanations of the mechanisms behind some frequent modes of early failure and ways to avoid them are suggested. it is shown theoretically, and partly confirmed by the analysis of unfortunately incomplete data from two paper mills over manly years, that accurate prediction of remaining bearing life requires (a) enough vibration measurements, (b) numerate records of operating conditions, (c) better discrimination between frequencies in the spectrum and (d) correlation of (b) and (c). This is because life prediction depends on precise knowledge about primary, harmonic and side band frequency amplitudes and their development over time, Much money could be saved because some policies-utilise as little as half of the bearing's potential life.

  • 324.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Kumar, U
    Improvement in effectiveness of vibration-based condition monitoring system in paper mills: two case studies1997In: 10th International congress and exhibiton on condition monitoring and diagnostic engineering management, 1997, p. 48-57Conference paper (Refereed)
  • 325.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Malmholt, O.
    Maintenance : eureka-maine project 1073 : euromaintenance guidelines: phase 2 : objectives and strategies : the swedish part1997Report (Other academic)
  • 326.
    Al-Najjar, Basim
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Wang, Wenbin
    Salford Univeristy.
    A Conceptual Model for Fault Detection and Decision Making for Rolling Element Bearings in Paper Mills2001In: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 7, no 3, p. 192-206Article in journal (Refereed)
    Abstract [en]

    Rolling element bearing failures in paper mill machines are considered in relation to their critical role in the machine function. The use of expensive, sophisticated and highly automated equipment and machines and the intention to achieve higher quality products, longer machine life, higher machinery effectiveness and safer operating processes were the main driving force motivating efforts to improve maintenance concept during the last 50 years. In this paper, a conceptual model that integrates the available condition information, the deterministic models used in condition monitoring based upon mechanical theory and the probabilistic models used in the area of operational research is developed and its applicability is discussed. This models covers fault detection of a mechanical component such as a rolling element bearing, prediction of its vibration level in the near future, assessment of the probability of failure of a component over a finite period of time of interest.

  • 327.
    Al-Najjar, Basim
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Williamsson, Ia
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    On the Possibility of Applying Condition-based Maintenance Approach on Software Instead of the Traditional Approach2009In: Comadem conference 2009. The 22nd international congress, condition monitoring and diagnostic engineering management / [ed] Aitor Arnaiz, Ana Arazabe, B K N Rao, 2009, p. 649-656Conference paper (Refereed)
    Abstract [en]

     

    Each minute of software system crashes and downtime in critical systems is often expensive or dangerous for both humans and the environment. Research reveals an intimidating large effort for maintenance; up to 90% of software cost is derived to maintenance and evolution. The attention on software maintenance has increased due to the safety aspect and its significant economic importance on information technology. Applying a statistical model for planning regular software maintenance action and modification can be misleading because similar software behave and age differently at various operating conditions. Standards that are used for software development and software maintenance do not treat software condition-based or proactive maintenance explicitly. Detecting deviations in the condition and performance of software systems at an early stage should decrease the economic losses.

    In this paper, different aspects of critical IT systems have been considered. The major result of this study is; a literature review, classification and analysis of maintenance approaches applied in industry and those in software reinforce that industrial approaches are conceptually comparable with software approaches. Also, investigating the possibility of adapting experiences from industry in the development of a new condition-based maintenance approach regarding software systems is viable. The main conclusions are that static and dynamic properties of software condition can be obtained by using tools and techniques, and if identifying and monitoring software degradation parameters it would be possible to apply a CBM policy on software. Consequently more research effort needs to be accomplished on condition-based software maintenance with a proactive-predictive approach.

  • 328.
    Al-Najjar, Hamid
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Maintenance impact on company´s profitability and competitiveness: Underhålls påverkan i företags lönsamhet och konkurrens2007Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    The aim of this thesis is to show the company the importance and the necessity of the maintenance, trough highlighting its role and impact on company’s profitability and competitiveness, and that’s happened within the analysing of the plant to figure out the failures and short stoppages, find out the causes behind them, convert them into money and the last step is to find out the most suitable and cost effective maintenance strategy based on some important factors such as economy, and quality to probably eliminate or reduce the number of failures and short stoppages. According to the analysis, capacity verifying data collection which the company has done during a random working daily shift and a technical faults list about the possibly failures and short stoppages which occur during the operation, it shows that there are some downtime due to management, operation and logistic, but the main focus was on the technical faults which has correlation with maintenance. In the result it shows which technical and mechanical problems the machines usually faces, the causes behind them, how much it cost the company when they breaks down and finally some suggestions and recommendations about how these problems can probably be solved based on economy and quality.

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  • 329.
    Al-Najjar, Hamid
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Gustafsson, David
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Uppträdande problem i elkraftsammanhang: Orsak, verkan och åtgjärder2006Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
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  • 330.
    Al-Najjar, Nasik
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    FRAMTIDA VATTENFÖRSÖRJNING FÖR VÄXJÖ KOMMUN: BEDÖMNING AV OLIKA ALTERNATIV2008In: Vatten, ISSN 0042-2886, Vol. 63, no 4, p. 299-311Article in journal (Other academic)
    Abstract [sv]

    Water supply in Växjö municipality has since 1887 been based on surface water from Helga lake. A water treatment plant was built in 1957 and was extensively reconstructed in 1969 but there are still problems to accomplish with drinking water quality, mainly related to temperature, smell and taste, managanese and aluminum rest. Present water consumption periodically approached the water treatment plant maximum capacity. A performed risk analysis showed that catastrophic consequences for the water supply could occur due to an accident in a nearby traffic route or discharges from an industrial area.

    In 1997 Växjö municipality decided to perform a comprehensive investigation of different alternatives for future water supply. Seven alternatives were evaluated including remedial measures at the present water treatment plant. The chosen alternative was based on supply and conveying ground water from Berga esker at Ljungby municipality. Re-infiltration of ground water will be used to guarantee required water quality and quantity and will be implemented in autumn 2008 with a planned supply of 200 l per second delivered to about 70.000 persons in the municipalities of Växjö and Alvesta. The article describes the different alternatives, motives for the chosen alternative and the evaluation procedure.

  • 331.
    Al-Najjar, Nasik
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    Hultman, Bengt
    Cost-Effective Water Supply and Sanitation2008In: 2nd-Environmental Conference-Water (KECW007), Dohuk Kurdistan Region in Iraq, 2008Conference paper (Refereed)
    Abstract [en]

    Water supply and sanitation have about the same goals all over the world. The needs for safe water supply and sanitation are obvious although not generally implemented. This depends often on the economical situation and bad management. Additional factors are effects of war actions and natural disasters as flooding of rivers and tsunamis. The strategies are, however, similar independent of the actual conditions. In this paper the strategies as developed in Sweden are described related to practical implementation of technology and management strategies. The experiences have shown on both mistakes and successful handling. Today, Sweden is involved in both adjusting policies according to European Union rules (as EU Water Framework Directive) and also in sharing experiences to facilitate international implementation of cost-effective methods.

  • 332.
    Al-Najjar, Nasik
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    Hultman, Bengt
    VA - SITUATIONEN I IRAK: PROBLEM OCH MÖJLIGHETER TILL MOTÅTGÄRDER2004In: VATTEN: Tidskrift för vattenvård, ISSN 0042-2886, Vol. 60, no 4, p. 269-274Article in journal (Other academic)
    Abstract [sv]

    A summary is given on the water and wastewater situation in Iraq before the Gulf war 1991, the situation after the Gulf war and the recent effects of the conflict 2003. The access of safe water was halved in certain counties after March 2003 and half of the sewage works was out of function with a discharge of untreated wastewater to rivers and channels. The supply of electricity was less than 4 hours per day in January 2004 and caused discharges of untreated sewage on streets etc. Leakage from the water net was estimated to 60%. The wastewater system in 3 out of 5 schools was estimated to be out of function and epidemics have especially affected children and caused an increased mortality. Special issues as illegal openings of water pipes and security have worsened the situation. Swedish knowledge in water and wastewater handling may have an important role in rebuilding water and wastewater handling in Iraq and different possibilities are given.

  • 333.
    Al-Najjar, Nasik
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Hultman, Bengt
    KTH, Stockholm.
    Water management and technology in Swedish municipalities.: Assessment of possibilities of exchange and transfer of experiences.2009In: An International Perspective on Environmental and Water Resources Conference, 2009Conference paper (Refereed)
    Abstract [en]

    The water and wastewater infrastructure began to be developed in Sweden more than one hundred years ago. Much attention was given, in the beginning, to fire prevention and hygienic problems with water borne diseases. Somewhat later storm sewers (combined system) were constructed to remove storm water and wastewater and then successively more efficient wastewater treatment plants were developed. Today water and wastewater handling is seen as a multidisciplinary subject where also attention is given to possible effects of climate changes and possibilities for resources recovery.

    Implementation of advanced water and wastewater systems involves not only different technologies but also effective administration and legislation. The implementation may be on national (also involving EU directives), regional and local scale. As a case study, the local implementation will be illustrated for the municipality Växjö in South Sweden with about 80,000 inhabitants.

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  • 334.
    Al-Ogaili, Rasha
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Al-Ogaili, Zaid
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    A Study on the Transition of the Adaptive into Responsive Web Design Methods on Smart Devices2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the fast-paced technological revolution, technology has formed itself differently to facilitate the way to users to get their needs. As a matter of fact, people nowadays rely to a great extent on the smart devices as one of the essential creations of technology. They tend to access any website or web-application(s) through these devices fast and easily. Thus, paying enough attention to the design of any website or web-application is a major issue. This thesis project discusses the Responsive and Adaptive Design Methods as two important methods in terms of Websites and Web-Design. The methods have been theoretically discussed and explained to present the essential differences between them. Moreover, MyMusiC website has been implemented to show the differences between these methods practically. The prominent difference between the Responsive and Adaptive de-signs of the website makes it easy for the users to figure out the difference between the two design methods in terms of accessibility and ease of navigation. The results showed that the Responsive design is more user-friendly and more preferred by the users than the Adaptive design, as the users tend to use their smart devices first when they want to access a website than the computers.

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  • 335.
    Al-qaissi, Mayss
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    A Study Of Multipath Wave Propagation Using Nero2d and FFT2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this report, the Fast Fourier Transform is described briefly. An implementation, inthe form of the Fortran code four1, is tested to verify the accuracy. A two-ray modelfor wave propagation above a flat earth is discussed. The case with AM modulation isimplemented in a Mathematica script. Calculations of the surface current density, withthe program NERO, are made to test the accuracy. The transient scattering from a PECcylinder is studied by means of the code run_nero that runs NERO repeatedly. From aspectrum calculated in this way, the impulse response is obtained by Fourier inversion.

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  • 336.
    Alriksson, Stina
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Conjoint analysis as a tool for communication and corporate environmental decision-making2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Conjoint analysis has been used extensively in marketing, transportation and healthcare for the past 50 years. Since the mid-1990s, it has also been applied to an increasing number of environmental issues. In this thesis, conjoint analysis is applied to environmental objectives of the Swedish steel industry. The aim of the research project has been to develop a method for eliciting stakeholder preferences for environmental issues and to present the results to the stakeholders through the multivariate data analysis method of partial least squares regression.

    This licentiate thesis is based on three studies: a literature review of all conjoint studies conducted on environmental issues, a pilot study in which a new method was developed, and a main study where this method was tested on four environmental objectives of the Swedish steel industry. Up to the present, 109 environmental conjoint studies have been carried out. Recently, studies in environ¬mental economy have dominated, with investigators trying to estimate a mone¬tary value on environmental values or products. The problem selection has varied widely, from ecosystem management and green products to waste and risk management.

    One trend among environmental conjoint studies has been to use conjoint methods that report results at a group level. In the pilot study here, conjoint analysis was combined with partial least squares regression to enable presentation of results at individual level. The benefit of individual-level results is that they can be used to initiate a dialogue between an industry and its stakeholders, as well as between different stakeholder groups. The presentation mode also allows the researcher to find segments of respondents that think alike, although perhaps from different groups. In the pilot study, cluster analysis was used successfully to find hidden segments among the respondents.

    In the main study, the method from the pilot study was used to elicit preferences for four environmental objectives of the Swedish steel industry: reduced use of non-renewable energy, reduced use of non-renewable resources, decreased emission of carbon dioxide and weight reduction of products. Six stakeholder groups participated in the study, and the results showed that decreased emission of carbon dioxide was the environmental objective that most participants prioritised highest. Lowest priority was given to weight reduction of products.

    Conjoint analysis combined with multivariate data analysis methods such as partial least squares regression, principal component analysis and cluster analysis has been verified as an effective method for eliciting stake¬holder preferences on industry-wide environmental issues.

  • 337.
    Alriksson, Stina
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Grip, Carl-Erik
    Luleå Tekniska Universitet.
    Studies of preferences as an extra dimension in system studies2011In: World Renewable Energy Congress – Sweden, 8–13 May, 2011Linköping, Sweden: Volume 7, Industrial Energy Efficiency / [ed] Bahram Moshfegh, Linköping: Linköping University Electronic Press, 2011, p. 1732-1739Conference paper (Refereed)
    Abstract [en]

    Industrial energy systems are complicated networks where changes in one process influence itsneighboring processes. The network complexity increases if production/use of bio fuel is introduced in anexisting system. Process integration can be a useful tool to study such systems and thus avoid sub optimization.However, changes in an industrial complex do not only influence the technical values of energy and materialefficiency. The social impact is also important and sometimes is comparable to that of technical factors.A process integration project has recently been carried out for a paper mill in northern Sweden with a side viewon future expansion with a bio refinery. An activity to study the social impacts were included through a Conjointanalysis, a stated preference method that combines statistics and interviewing technique.The results indicate that the participants are divided in four groups, the largest group focusing on a change in theprocess towards a bio refinery, the second largest focusing on the local environment. The third and fourth groupboth look at the local forestry, one group wanting to increase local forest production, and one rejecting anincrease.

  • 338.
    Alriksson, Tobias
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Visualisering av byggprojekt i Revit2014Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
    Abstract [sv]

    Rapporten avhandlar visualiseringen i marknadsföringsstadiet av ett byggnadsprojekt med tillämpning på Trivselhus bostäder. För att få en grund till vad som ska ändras gällande företagets nuvarande visualisering har intervjuer genomförts med samtliga berörda parter. Dessa är säljare, kunder och husdesigners. Efter detta har två förslag till förändringar av nuvarande visualiseringar arbetats fram i Revit med intervjuerna som underlag.

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  • 339.
    Alsouda, Yasser
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    An IoT Solution for Urban Noise Identification in Smart Cities: Noise Measurement and Classification2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Noise is defined as any undesired sound. Urban noise and its effect on citizens area significant environmental problem, and the increasing level of noise has become a critical problem in some cities. Fortunately, noise pollution can be mitigated by better planning of urban areas or controlled by administrative regulations. However, the execution of such actions requires well-established systems for noise monitoring. In this thesis, we present a solution for noise measurement and classification using a low-power and inexpensive IoT unit. To measure the noise level, we implement an algorithm for calculating the sound pressure level in dB. We achieve a measurement error of less than 1 dB. Our machine learning-based method for noise classification uses Mel-frequency cepstral coefficients for audio feature extraction and four supervised classification algorithms (that is, support vector machine, k-nearest neighbors, bootstrap aggregating, and random forest). We evaluate our approach experimentally with a dataset of about 3000 sound samples grouped in eight sound classes (such as car horn, jackhammer, or street music). We explore the parameter space of the four algorithms to estimate the optimal parameter values for the classification of sound samples in the dataset under study. We achieve noise classification accuracy in the range of 88% – 94%.

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    An IoT Solution for Urban Noise Identification in Smart Cities
  • 340.
    Alsouda, Yasser
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Pllana, Sabri
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM).
    Kurti, Arianit
    RISE Interactive, Sweden.
    A Machine Learning Driven IoT Solution for Noise Classification in Smart Cities2018In: Machine Learning Driven Technologies and Architectures for Intelligent Internet of Things (ML-IoT), August 28, 2018, Prague, Czech Republic, Euromicro , 2018, p. 1-6Conference paper (Refereed)
    Abstract [en]

    We present a machine learning based method for noise classification using a low-power and inexpensive IoT unit. We use Mel-frequency cepstral coefficients for audio feature extraction and supervised classification algorithms (that is, support vector machine and k-nearest neighbors) for noise classification. We evaluate our approach experimentally with a dataset of about 3000 sound samples grouped in eight sound classes (such as, car horn, jackhammer, or street music). We explore the parameter space of support vector machine and k-nearest neighbors algorithms to estimate the optimal parameter values for classification of sound samples in the dataset under study. We achieve a noise classification accuracy in the range 85% -- 100%. Training and testing of our k-nearest neighbors (k = 1) implementation on Raspberry Pi Zero W is less than a second for a dataset with features of more than 3000 sound samples.

  • 341.
    Alsouda, Yasser
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM).
    Pllana, Sabri
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM).
    Kurti, Arianit
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM).
    IoT-based Urban Noise Identification Using Machine Learning: Performance of SVM, KNN, Bagging, and Random Forest2019In: Proceedings of the International Conference on Omni-Layer Intelligent Systems (COINS '19), New York: ACM Publications, 2019, p. 62-67Conference paper (Refereed)
    Abstract [en]

    Noise is any undesired environmental sound. A sound at the same dB level may be perceived as annoying noise or as pleasant music. Therefore, it is necessary to go beyond the state-of-the-art approaches that measure only the dB level and also identify the type of noise. In this paper, we present a machine learning based method for urban noise identification using an inexpensive IoT unit. We use Mel-frequency cepstral coefficients for audio feature extraction and supervised classification algorithms (that is, support vector machine, k-nearest neighbors, bootstrap aggregation, and random forest) for noise classification. We evaluate our approach experimentally with a data-set of about 3000 sound samples grouped in eight sound classes (such as car horn, jackhammer, or street music). We explore the parameter space of the four algorithms to estimate the optimal parameter values for classification of sound samples in the data-set under study. We achieve a noise classification accuracy in the range 88% - 94%.

  • 342.
    Alsterlind, Stina
    Linnaeus University, Faculty of Engineering and Technology, Kalmar Maritime Academy.
    Att leva med en sjöfarare: En kvalitativ studie ur partnerns perspektiv2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A profession at sea involves alternating away/home periods, which means a special situation for the seafarer in reconciling profession and family life. This rotation system can also be assumed to have consequences fot those who live with a seafarer. Against this backgrund, the purpose of this study was to illustrate how the rotation system may effect the partners´daily lives ande thier ralationship with the saefarer. A qualitaive approach was used because I wanted to understand and describe the respondents´personal experiences. The results showed that the perception among the respondents varied. The problematic aspects that emerged were above all the absence of acxact dates for the serfarer to sign on and off the vessel. Thay found it difficult to be proactive and make common plans when the dates often changed. The positive aspects that were highlighted included; quality time together, own time and natural breakes in the realtionship which could lead to positive emotions of renewal. The key to getting the relationship to work was seen as a positive attitude and a common compromise from both parties.

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    Att leva med en sjöfarare - En kvalitativ studie ur partnerns perspektiv
  • 343.
    Al-Sundook, Amaar
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Testkrets för lavingenombrott för högspännings diod2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    High frequency power converters are used for both consumer products and in industrial power plants. In some industrial applications, a very high output voltage can be obtained. A transformer gives a high voltage in the secondary, which is then rectified by diodes. High voltage diodes are important components in the rectifier to withstand tough work so that the transformer supplying the desired high voltage.

    Alstom in Växjö is working with Air Pollution Control Equipment. They develop marketing and executing projects with advanced systems and products for smoke gas cleaning to power plants and the industry. The objective is to minimize the risk of negative impact on the environment. In Växjö, Alstom also has a large unit for service, which also consists of several local offices covering all parts of the country.

    Another important facility in Växjö is Alstom's global research and development center, where new environmental solutions and technologies are tested in large scale format. The test center has a long tradition of environmental control systems, but during the past decade the center has been one important platform for the development of Alstom’s products for carbon particle separation (electrostatic filter). These electrostatic filters use diodes as the main component of a high frequency transformer. The diodes must be specially designed to withstand high voltages. The development of the Alstom invented a new type of power diode.  The idea is that the diode is withstand of 10kV in the reverse direction.

    The goal of this work is based on building a facility to test the new diode and see how the diode works with high voltage in the reverse direction condition.

  • 344.
    Alsyouf, Imad
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Cost Effective Maintenance for Competitve Advantages2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes the role of cost effective maintenance in achieving competitive advantages. It explores by means of a survey which maintenance practices are used, and how maintenance policies are selected in Swedish industries. Also, it suggests a model for selecting the most cost effective maintenance policy, and how to improve the effectiveness of condition based maintenance decision-making. Finally it discusses how to assess the impact of maintenance practices on business strategic objectives.

    The main results achieved in the thesis are 1) A better understanding of maintenance organisation, management, systems and maintenance status in Swedish industry. For example, it was found that about 70% of Swedish companies still consider maintenance as a cost centre. Preventive and predictive maintenance approaches are also emphasised. 2) Most Swedish firms, i.e. about 81%, use the accumulated knowledge and experience within the company as a method for maintenance selection. Besides, about 31% use a method based on modelling the time to failure and optimisation. About 10% use failure mode effect and criticality analysis (FMECA) and decision trees and only 2% use multiple criterion decision-making (MCDM). However, the most used maintenance selection method is not the one most satisfactory to its users. Furthermore, about 30% use a combination of at least two methods. 3) A practical model for selecting and improving the most cost effective maintenance policy was developed. It is characterised by incorporating all the strengths of the four methods used in industry. 4) A mechanistic model for predicting the value of vibration level was verified both at the lab and in a case study. 5) A model for identifying, assessing, monitoring and improving the economic impact of maintenance was developed and tested in a case study. Thus it was proved that maintenance is no longer a cost centre, but could be a profit-generating function.

    To achieve competitive advantages, companies should do the right thing, e.g. use the most cost effective maintenance policy, and they should do it right, e.g. ensure that they have the right competence. Furthermore, they should apply the never-ending improvement cycle, i.e. Plan-Do-Check-Act, which requires identifying problem areas by assessing the savings and profits generated by maintenance and monitoring the economic impact of the applied maintenance policy. Thus, they would know where investments should be allocated to eliminate the basic reasons for losses and increase savings.

    The major conclusion is that proper maintenance would improve the quality, efficiency and effectiveness of production systems, and hence enhances company competitiveness, i.e. productivity and value advantages, and long-term profitability.

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  • 345.
    Alsyouf, Imad
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Maintenance practices in Swedish industries: Survey results2009In: International Journal of Production Economics, ISSN 0925-5273, E-ISSN 1873-7579, Vol. 121, p. 212-223Article in journal (Refereed)
    Abstract [en]

    The purpose of this paper is to investigate the maintenance practices that are used in Swedish industry. The study was performed by conducting a cross-sectional survey within Swedish firms that have at least 100 employees. The main results achieved from the study show that the role of maintenance is not highly recognised. There is a need to spend and invest more in maintenance, which is considered by the majority of Swedish industries as a necessary expense. Although about 13% of the maintenance department time is spent on planning maintenance tasks, nevertheless, about one third of the time is spent on unplanned tasks. There is a need for more adoption of maintenance concepts such as total productive maintenance (TPM) and reliability-centred maintenance (RCM). The lack or ineffectiveness of planning and scheduling can significantly restrict the maintenance department in achieving its objectives and can thus prevent the company from maximising business profits and offering competitive advantages.

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  • 346.
    Alsyouf, Imad
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    The Role of Maintenance in Improving Companies' Productivity and Profitability2002In: Proceedings IFRIMmmm: Maintenance mangagement & modelling conference, Växjö, 2002, Vol. 105, no 1Conference paper (Refereed)
  • 347.
    Alsyouf, Imad
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    The Role of Maintenance in Improving Companies' Productivity and Profitability2007In: International Journal of Production Economics, ISSN 0925-5273, Vol. 105, no 1, p. 70-78Article in journal (Refereed)
    Abstract [en]

    This paper illustrates how an effective maintenance policy could influence the productivity and profitability of a manufacturing process. It was possible to show how changes in the productivity affect profit, separately from the effects of changes in the uncontrollable factors, i.e. price recovery. The main results of the case study performed at a Swedish paper-mill showed that a paper-mill machine could, ideally, generate extra profit of at least 7.8 million Swedish kronor (SEK) (approximately US$ 0.975 million) per year, i.e. 12.5% of its yearly maintenance budget, if it avoids all unplanned stoppages and bad quality production due to maintenance-related causes. Thus, maintenance is not a cost centre, but a profit generating function.

  • 348.
    Alsyouf, Imad
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Wind energy system reliability and maintainability, and operation and maintenance strategies2010In: Wind energy systems: optimising design and construction for safe and reliable operation, Cambridge: Woodhead Publishing Limited, 2010, no 10, p. 303-328Chapter in book (Refereed)
    Abstract [en]

    This chapter discusses the reliability, operation and maintenance strategies for wind power systems. It examines the role of systems engineering in optimising the aspects of a system relating to reliability, supportability and maintainability. It considers various maintenance approaches and the role of proper maintenance practices in providing a secure and reliable energy supply at the right cost. It discusses the importance of identifying and understanding the relevant cost factors associated with wind power systems, based on lifecycle costing and using relevant performance measures to help select a cost-effective maintenance approach. It then reviews some efforts aimed at improving the design, production, construction, operation and maintenance of wind power systems. Finally, some future trends are discussed in the areas of operation and maintenance of wind power systems.

  • 349.
    Alsyouf, Imad
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Alzghoul, Ahmad
    Luleå University.
    Soft computing applications in wind power systems: a review and analysis2009In: European Offshore Wind 2009 Conference proceedings, 2009Conference paper (Other academic)
    Abstract [en]

    This paper reviews, analyses, discusses and summarises the recent research and development and trends in the applications of soft computing in the field of wind power systems. We show the usage and the influence of soft computing on the different aspects of wind power systems especially in the field of operation and maintenance. This work provides the state of the art in this area which will be a good guidance for future research work. The main results achieved from the study show that the soft computing techniques are adequate for solving the different challenges at the different phases of the life cycle processes of wind power systems.  Using the various soft computing techniques with wind power systems proved to be useful for the wind energy business. Using these tools contribute by improving the robustness of the decisions at different phases of the system's life cycle. Soft computing can enhance the efficiency and effectiveness of the operation and maintenance of offshore wind power systems through improving the availability levels. Thus, providing secure, sustainable and competitive energy supply for the future.

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  • 350.
    Altergren, Andreé
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Förberedelse till modernisering av styrsystem för produktion av processvatten2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The heat and power station Allöverket in Kristianstad produced the process water in a plant called the total desalination. In this plant which consists out of two identical lines, they let the incoming water passing through ion exchangers to replace the undesired ions in the water to more desired ions. The reason for doing this is that the undesired ions in the water give coatings on the turbine. When the ion exchangers have been saturated, they must be restored to the original condition. This is done by starting a regeneration program, which consists of a number of steps such as back flushing, intake of chemicals and four different flushes. There are limits on the conductivity and the content of silicon in the water that will be delivered. But there is only measurement of the conductivity connected to the control system, and because of this they control the plant with different timers. To the control system there is connected a number of centrifugal pumps, solenoid valves and instrumentation for measurement of conductivity. In the total desalination sits a Siemens S5 control system that controls the plant after amount of water, conductivity and different times of the sequences. The control functions are now located on a control cabinet out of the factory. The Siemens S5 control system is old and outdated and will be changed to an ABB 800xA control system. This control system they already use to control other parts of the factory from the control room. With this study I have developed a new functional description of the plant and it consists of function diagrams which describes how the software controls the plant today. To the function description, I have also made a new technical description and revised the process scheme so that all documentation of the plant says the same thing.

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    Förberedelse till modernisering av styrsystem för produktion av processvatten
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