Ändra sökning
Avgränsa sökresultatet
567891011 351 - 400 av 1472
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 351.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Banjevic, Dragan
    C-MORE Lab, University of Toronto.
    Jardine, Andrew K. S.
    C-MORE Lab, University of Toronto.
    Developing Effective Spare Parts Estimations Results in Improved System Availability2010Ingår i: 2010 proceedings: Annual Reliability and Maintainability Symposium : San Jose, California, USA, 25 - 28 January 2010, Piscataway, NJ: IEEE Communications Society, 2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Production and manufacturing firms are under great pressure to continuously reduce their production costs in order to stay competitive. Industrial operation cost analysis shows that, in general, maintenance represents a significant proportion of the overall operating cost. For instance, the cost of maintenance in the highly mechanized Kiruna underground iron ore mine in Sweden is 30-50% of the total operating cost. Spare parts availability, an issue of the maintenance process, is studied in this paper. Simply stated, production can be enhanced by the increased availability of functional machinery and the subsequent minimization of the total production cost. Spare parts estimation based on machine reliability characteristics and operating environment is a pragmatic method to improve supportability; it can guarantee non-delay in spare parts logistics which can ultimately improve production output. This study uses an improved statistical-reliability (S-R) approach which incorporates system/machine operating environment information in systems reliability analysis. It selects a multiple regression type of analysis based on Cox’s proportional hazards modeling (PHM). It considers a parametric approach with a baseline Weibull hazard function and time independent covariates and analyzes the influence of operating environment factors on this model. Based on the results of analyses, a mathematical model for spare parts prediction in component level for non-repairable parts is developed and the findings are validated through a case study in the Swedish mining industry. The study finds that the outputs represent a significant difference in the required spare parts estimation when considering the influence of the system operating environment. The difference is significant in the sense of spare parts forecasting and inventory management; this can enhance the availability of parts and consequently of machines resulting in economical operation and cost savings.

  • 352.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Banjevic, Dragan
    University of Toronto.
    Jardine, Andrew K.S.
    University of Toronto.
    Optimizing product support (spare parts procurement) strategy by considering system operating environment: A case study2009Ingår i: 13th IFAC Symposium on Information Control Problems in Manufacturing 2009: Moscow, Russia, 3 - 5 June 2009, Red Hook: Curran Associates, Inc., 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Existing industrial system / machinery availability depends highly on the form and the level of product support. Product support, which is also referred to as after sale service to the product, is important for the customer as well, because it assures the expected function of the product in its operational phase. Product support is affected by different factors, such as reliability and maintainability characteristics and the operating environment of the product. The forecasting of required product support and spare parts based on these factors is one approach for product life cycle cost optimization along with system availability maximization. This paper describes a method to estimate the spare part requirements based on an estimation of reliability of the existing product under the influence of the product-operating environment. Subsequently, in a case study, the management of the spare parts inventory based on the geographical location and required performance of the product will be addressed.

  • 353.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Banjevic, Dragan
    C-MORE Lab, University of Toronto.
    Jardine, Andrew K.S.
    C-MORE Lab, University of Toronto.
    Product support improvement by considering system operating environment: a case study on spare parts procurement2012Ingår i: International Journal of Quality & Reliability Management, ISSN 0265-671X, E-ISSN 1758-6682, Vol. 29, nr 4, s. 436-450Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ongoing availability of existing industrial systems/machines depends to a great extent on the form and level of product support. Product support, or the after sale service of a product, is important because it assures the expected function of the product in its operational phase. Product support is affected by a number of factors, including system reliability and maintainability characteristics and the operating environment. The purpose of this paper is to analyze the influence of time independent external factors of industrial systems on product support requirements and spare parts need.

  • 354.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Famurewa, Stephen Mayowa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Hoseinie, Hadi
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Railway switches and crossings reliability analysis2016Ingår i: 2016 IEEE International Conference on Industrial Engineering and Engineering Management, 2016, Vol. 2016-December, s. 1412-1416, artikel-id 7798110Konferensbidrag (Refereegranskat)
    Abstract [en]

    Switches and crossings (S&Cs) connect the rail network, guiding trains from one track to another and supporting path crossing. They are critical systems given the frequency of their functional failure and the consequences on the operation, cost and safety of railway transportation. Reliability studies are required to support the transport objective of providing dependable, sustainable and cost effective transportation. The main objective of this study is to assess the reliability characteristics of S&Cs based on field data collection. As field failure data have censored nature, commercial packages have not been satisfactory for processing them; therefore, the study uses a special statistical software package RDAT® (Reliability Data Analysis Tool). The availability of the studied switches and crossings is estimated based on the estimated reliability characteristics. The results show the availability of the S&Cs varies between x and y. This is useful information, as it helps the contractor plan and schedule maintenance. It also helps the asset owner to identify units whose performance is below the desired target and to make replacement decisions.

  • 355.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Hamodi, Hussan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Hoseinie, Hadi
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Environmental friendly manufacturing and support: Issues and challenges2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Environmentally Conscious Manufacturing and Product Support (ECMPS) is animportant issue driven by concern for the escalating deterioration of the environment.ECMPS involves integrating environmental thinking into the design of a product, theselection of materials, manufacturing processes, delivery and support to consumers, andend-of-life management of the product after its useful life has ended. Both academia andindustry are interested in finding solutions in this newly emerging research area. Relatedresearch is on pollution prevention, remanufacturing, disassembly, life cycle of products,after sale support and material recovery. The aim of this study is emphasizing the productdesign, operation, maintenance and disassembly effects on environment, and how theseissues can be considered in manufacturing phase to minimize the negative environmentalimpact.

  • 356.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Hoseinie, Hadi
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Garmabaki, Amir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Reliability considerations in automated mining systems2015Ingår i: International Journal of Mining, Reclamation and Environment, ISSN 1748-0930, E-ISSN 1748-0949, Vol. 29, nr 5, s. 404-418Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Automation is the operation of machinery or processes by devices, such as robots and machines, able to make and execute decisions without human intervention. Automation is one of the most attractive research and development areas in mining, as it aims to solve many technical, production and safety problems in current and future mining. This paper studies the structure of automated mining systems from a reliability and failure occurrence perspective. It reviews the main subsystems and related failure modes. Based on field investigation and a literature review, it highlights some critical issues and technical difficulties. Finally, it presents some challenges for future automated mines and offers some related solutions

  • 357.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Hoseinie, Hadi
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Context-driven mean residual life estimation of mining machinery2018Ingår i: International Journal of Surface Mining, Reclamation and Environment, ISSN 1389-5265, s. 486-494Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Maintenance is crucial to ensure production/output and customer satisfaction in the mining sector. The cost of maintenance of mechanised and automated mining systems is very high, necessitating efforts to enhance the effectiveness of maintenance systems and organisation. For effective maintenance planning, it is important to have a good understanding of the reliability and availability characteristics of the systems. Determining the Mean Residual Life (MRL) of systems allows organisations to more effectively plan maintenance tasks. In this paper, we use a statistical approach to estimate MRL and consider a Weibull proportional hazard model (PHM) with time-independent covariates to model the hazard function so that the operating environment could be integrated into the reliability analysis. The paper explains our methods for calculating the conditional reliability function and computing the MRL as a function of the current conditions. The model is verified and validated using data from the hydraulic system of LHD equipment in a Swedish mine. The results are useful to estimate the remaining useful life of such systems; the method can be used for maintenance planning, helping to control unplanned stoppages of highly mechanised and automated systems.

  • 358.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Hoseinie, Hadi
    Hamedan University of Technology.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Lean mining2016Ingår i: The Routledge companion to lean management / [ed] Torbjørn H Netland; Daryl J Powell, New York: Routledge, 2016, s. 302-310Kapitel i bok, del av antologi (Refereegranskat)
  • 359.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Consideration of operating environment when optimizing spare parts inventories2009Ingår i: 2009 proceedings: 15th ISSAT International Conference Reliability and Quality in Design : August 6 - 8, 2009, San Francisco, California, USA / [ed] Hoang Pham, Piscaaway, NJ: International Society of Science and Applied Technologies , 2009, s. 315-319Konferensbidrag (Refereegranskat)
    Abstract [en]

    Spare parts estimation, consumption and management are greatly influenced by the reliability characteristics of system or components under consideration. Any maintenance policies and spare parts planning without considering the reliability characteristics are not optimum. Therefore it is important to study and analyse the reliability characteristics before making decision concerning spare parts planning. It is known that the operating environmental conditions in which the system is to be operated, such as temperature, humidity, dust, load, voltage stress, etc. often have considerable influence on its reliability characteristics. These factors, in fact affect the failure rate of a repairable system and non-repairable component, but are usually ignored in the reliability analysis. In general, new products are often used under conditions that are not anticipated. It is common to modify the predicted life length and reliability characteristics of product by considering the environmental and other factors. In this paper a general approach of integrating the system operating environment in dimensioning of spare parts planning is briefly studied. Two approaches, Poisson and renewal process are considered in the analyses of system/component failure behaviour. Eventually, two case studies that are used the mentioned methods are presented. The main purpose of the paper is to highlight the effect of system operating environment in system behaviour and consequently spare parts needs.

  • 360. Ghodrati, Behzad
    et al.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Operating environment based maintenance and spare parts planning: a case study2004Ingår i: Advanced Reliability Modeling: Proceedings of the 2004 Asian International Workshop (AIWARM 2004) / [ed] Tadashi Dohi; Won Young Yun, World Scientific and Engineering Academy and Society, 2004, s. 125-132Konferensbidrag (Refereegranskat)
    Abstract [en]

    Maintenance strategies and spare parts consumption is greatly influenced by the reliability characteristics of system or components under consideration. Any maintenance policies or spare parts planning without considering the reliability characteristics are not optimum. Therefore it is important to study and analyse the reliability characteristics before making decision concerning spare parts and maintenance planning. It is known that the operating environmental conditions in which system is to be operated, such as temperature, humidity, dust, load, voltage stress, etc. often have considerable influence on its reliability characteristics. These factors, in fact affect the failure rate of a repairable system and non-repairable components, but are usually ignored in the reliability analysis. Thus operating environment should be considered as an important factor while making decision about maintenance, spare parts planning, product support, and service delivery strategies. In general, new products are often used under conditions that are not anticipated. It is common to modify predicted life length and reliability characteristics of product by considering the environmental and other factors. The purpose is to incorporate the effect of the environmental factors such as temperature, humidity, dust, voltage stress, etc in reliability analysis.

  • 361. Ghodrati, Behzad
    et al.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Operating environment-based spare parts forecasting and logistics: a case study2005Ingår i: International Journal of Logistics, ISSN 1367-5567, E-ISSN 1469-848X, Vol. 8, nr 2, s. 95-105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In today's highly dynamic and constantly changing industrial environment, issues relating to product support are becoming increasingly important. However, the extent of attention given to these issues varies considerably depending on the perspective of the interested person or profession. These are likely to vary from design engineers at the conceptual stages of product development to manufacturers and users in the latter stages. Additionally, the make up a particular product support package varies according to type of system/mission, application and stages of machine/system life. The lack of timely or incomplete support is likely to cause unexpected downtimes, which in turn will lead to losses for which one is unable to compensate. Falling within the definition of product support items are spare parts. The lack of a critical spare part can cause untimely stoppage of machine/system. Forecasting of product support and spare parts requirements based on reliability and maintainability (R&M) characteristics of system/components together with system operating environment(s) is one of the most effective strategies for prevention of unplanned stoppages. In this paper the effects of environmental factors on hydraulic brake pump used in mine loaders are presented and analysed. The reliability of this non-repairable part and its operational impact are assessed for both when the environmental factors are considered and when they are ignored. From the study, it is found that the forecasting for brake pump inventory is more accurate when environmental factors are included in the calculations. These results demonstrate the value of the inclusion of environmental factors data in the product support logistics' optimisation process.

  • 362.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Project: Cost effective availability enhancement of switches and crossings using reliability analysis2012Övrigt (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    The main reason for the complexity of the railway system is that it is often a mixture of components of different age and status that have to work together in a system.Replacement of components is also a continuous and ongoing process. Today the railway infrastructure is therefore like a patchwork that has to perform to higher demands. For this reason changes have to be carefully executed.Infrastructure managers must keep infrastructure highly available so that railway undertakings (train operating companies) can deliver a high quality service at affordable price to end users. Expected increases in traffic volume will impose higher utilization of existing capacity and reduce the time available for maintenance and unplanned interruptions.Maintenance must therefore be performed near capacity limits, time between asset renewals should be long enough to balance maintenance cost and acquisition cost and components replaced by deferred or planned maintenance.In summary, the key goal is to achieve availability target cost effectively, or to minimize life-cycle cost subject to availability constraints. Availability itself is a function of reliability and maintainability of a system as well as the maintenance support. It implies that for achieving high availability we need to go through reliability, maintainability, product support and service delivery approaches. It is proposed to apply RAMS (reliability, availability, maintainability and safety) analysis along with advanced statistics and decision support techniques in order to address this need. Intelligent data processing will allow understanding the real reliability characteristics of the assets to be maintained. Furthermore simulation and optimization techniques will be applied in order to adapt the maintenancestrategy so as to achieve minimum cost while guaranteeing target availability. If maintenance is organized in such a way as to minimize equipment downtime, availability will be maximized and it will be possible to extract as much capacity as possible out of existing assets. In this way, asset renewal can be postponed as much as possible, so as to minimize total life cycle cost without detriment to service quality.Therefore, the goal of proposed study is summarized as: developing a method to improve switches and crossings availability cost effectively through maintenance optimization using reliability analysis.

  • 363. Ghodrati, Behzad
    et al.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Reliability and operating environment-based spare parts estimation approach: a case study in Kiruna Mine, Sweden2005Ingår i: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 11, nr 2, s. 169-184Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A case study was conducted to examine system reliability and operating environment, which are two important parameters, in spare parts estimation approach. It was found that required number of spare parts could be obtained based on technical and life parameters. It was also studied that forecasting the required number of spare parts, based on technical characteristics and operating environmental conditions of a system, is one of the best ways to optimize unplanned stoppages. It is suggested that to avoid downtime regarding the unavailability of spare parts, the company should take the operating environmental factors into consideration while estimating the spare parts need.

  • 364.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Ahmadzadeh, Farzaneh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Remaining useful life estimation of mining equipment: A case study2012Ingår i: Proceedings of MPES 2012, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    To ensure the production/output and customer satisfaction in mining sector the estimation of Remaining Useful Life of mining machineries is a prime. In this paper we used the reliability analysis in order to estimate an optimal mining equipment repair/replacement policy by estimating their remaining useful life. The proportional hazard model was used in reliability analysis to be realistic and take the operational influencing factors in calculation. Methods are presented for calculating the conditional reliability function and computing the remaining useful life (RUL) as a function of the current conditions to guarantee the desired output. The model is applied in the hydraulic jack unit of LHD machine in an underground mine in Sweden. A Weibull proportional hazard model (PHM) with time-independent covariates was considered for the hazard function in an illustration of the proposed model. Presented results can be used, e.g. for developing of preventive maintenance plan or replacement intervals based on the conditional probability of failure or RUL.

  • 365.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Johansson, John
    Sverige.
    Project: CAMM - Lean mining2012Övrigt (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    The current status of Scandinavian mining industry is characterized by semi-autonomous to autonomous and intelligent production machines. Since many of these autonomous machines are expected to perform round the clock, the importance of system characteristics such as reliability, availability, flexibility and controllability are of prime importance. Other area is focused on seamless integration of information to realize the vision of autonomous mining system and been actively developing and implementing the concept of collaborative and intelligent operation and maintenance for operating systems. Therefore, the vision of a Digital Mine with autonomous mining systems seems a possibility especially with the advent of new and emerging technologies together with willingness of mining industry to make investment towards semi autonomous and autonomous mining systems.For achieving lean production, all the processes and systems need to communicate in real time so as to eliminate uncertainty and address the critical issues and challenges often arising at short notices in a continuously changing environment as found in mining operations.The plan for research development intends to take the mining industry several steps forward in creating a reliable robust and productive autonomous mining system. Our goal is to build a state of the art research capability in the area of mine production system by working on the following subproject addressing the critical issues to realise the vision of lean mining system.Work plan A: Improvement of production availability and delivery assuranceWork plan B:Rock and machine interfaceWork plan C:Remaining useful life of mining systemsWork plan D:Integration of mine work environment into production systems

  • 366.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Kumar, Uday
    Kumar, Dhananjay
    Nokia.
    Product support logistics based on product design characteristics and operating environment2003Ingår i: Proceedings of the 38th annual International Logistics Conference and Exhibition: SOLE 2003, Society of Logistics Engineers , 2003Konferensbidrag (Refereegranskat)
    Abstract [en]

    To improve the reliability, maintainability, and supportability (RMS) of a product, it is necessary to understand the factors influencing the product performance. This factors can be user environment, human (operator) aspects like training, and technical characteristics of the product. The environmental conditions in which the equipment is to be operated, such as temperature, humidity, dust, road conditions, maintenance facilities, maintenance crew training, operators' skill, etc, often have considerable influence directly on the product reliability and indirectly on the product supportability characteristics. Thus operating environment should be seriously considered while dimensioning product support and service delivery performance strategies, since it will have an impact on operational and maintenance cost and service quality to provide product support plan in an optimal condition. Spare parts are classified, as a product support items whose availability is important when planned or unplanned maintenance is to be carried out. Forecasting the required support/spare parts based on technical characteristics and operating environmental conditions of a system, is the one of the best ways for optimizing unplanned stoppages. This paper discusses about product support (required spare part) logistics based on product design characteristics and operating environment both for conventional and functional products.

  • 367. Ghodrati, Behzad
    et al.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Kumar, Dhananjay
    Nokia.
    Product support (spare parts procurement) strategy based on reliability characteristics and geographical location2003Ingår i: International Conference on Industrial Logistics: Proceedings / [ed] Lilian Barros; Petri Helo; Tauno Kekäle, Vaasa: University of Vaasa , 2003, s. 222-235Konferensbidrag (Refereegranskat)
    Abstract [en]

    Product support, which is also referred to after sale service to the product is important for customer because it increases the availability of the product and it assures the expected function of the product in its operational phase. It gets affected by many factors such as - reliability and maintainability characteristics and geographical location of the product. By highlighting the reliability issues and geographical distribution of product in design and manufacturing phases, the product life cycle cost (LCC) can be optimized. One of the important steps in product design is the decision making for design out maintenance (DOM) and/or designs for maintenance (DFM). The DOM alternative leads to produce high reliable, and vice versa, whereas the DFM assure the similar performance with lower reliability. However, the need for product support and spare parts must be considered in both alternatives. The forecasting of required product support and spare parts based on reliability-maintainability characteristics is one approach for the product LCC optimization. Consequently, spare parts inventory management based on geographical distribution and reliability characteristics of the product can be also used as an alternative. This article describes a method to forecast the spare part requirements based on reliability estimation of the existing product under the influence of the product-operating environment. Subsequently the management of the spare parts inventory will be discussed based on the geographical location and required performance of the product.

  • 368.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Kumar, UdayLuleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.Schunnesson, HåkanLuleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Proceeding of the 26th International Symposium on Mine Planning and Equipment Selection: MPES 20172017Proceedings (redaktörskap) (Refereegranskat)
  • 369.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Markeset, Tore
    Centre for Industrial Asset Management, University of Stavanger.
    Ahmadi, Alireza
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Enhancement of mining machineries performance through supportability2011Ingår i: International Journal of COMADEM, ISSN 1363-7681, Vol. 14, nr 2, s. 35-43Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cost analysis of mining operations in general shows that 30 to 50 percent of direct mining costs are related to maintenance and losses related to lost production during equipment downtime. To reduce these losses one first needs to improve the equipment reliability and thereafter to reduce the downtime losses through improved maintainability and supportability. The mining operational environment is often harsh and may severely impact all three of these abilities. In this paper we focus on how to improve the estimation of spare parts by taking into account the operating environment in the estimation models. By having better models to predict spare parts needs, one can avoid logistics delays and thereby reduce downtime. In this study we develop an improved statistical-reliability (S-R) analysis approach that take into account the system/ machine operating environment. The analysis approach is multiple regressions based on Cox’s proportional hazards modeling (PHM). Subsequently, in a case study, the management of the spare parts inventory based on the economic order quantity and required performance of the product is addressed.

  • 370.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Rahimdel, Mohammad Javad
    Department of Mining Engineering, Sahand University of Technology, Tabriz, Iran.
    Taghizadeh Vahed, Amir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Fuzzy Risk Prioritization of the Failure Modes in Rolling Stocks2018Ingår i: / [ed] Kay Chen TAN, Roger JIAO, Surendra M GUPTA, Kongkiti PHUSAVAT and Min XIE, Piscataway, NJ: IEEE, 2018, s. 108-112Konferensbidrag (Refereegranskat)
    Abstract [en]

    Failure Mode and Effects Analysis (FMEA) is extensively used to identify and eliminate the potential failures in products, processes, designs, and services. In this approach, the detectability, occurrence and the severity of each identified failure mode need to be determined usually by a FMEA team. This paper aims to prioritize the failure modes of rolling stocks by integrating Analytical Hierarchy Process (AHP) and Risk Priority Number (RPN). To reduce the uncertainties and ambiguities, all calculations are done in the fuzzy environment instead of the crisp values. The importance degree of each failure mode is determined and then the overall fuzzy RPN is calculated. In this way, the critical failure modes are defined to make an efficient maintenance decision.

  • 371.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Toosi, Amir
    Sharif University of Technology.
    Monitoring the condition of rolling element and plain bearings2007Ingår i: 4th International conference on maintenance: Iran - Teheran, 13-14 Nov 2007, 2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    Experience has proved that maintenance cost of rotating equipments is a huge expense of different industries. The need for reducing these kinds of expenditures reveals the importance of condition monitoring day by day. Applying different methods of condition monitoring allows maintenance departments to perform their activities based on the current condition of machineries not on the basis of approximated machineries life length arising from statistics. Due to the Prognosis and diagnosis of failures as duty of condition monitoring units and with proper maintenance planning of the plants, maintenance activities could result in reduction of repair and maintenance costs. In this report we study the methods, tools and effectiveness of condition monitoring of rolling-element (anti-friction) and plain (journal) bearings and their fault diagnosis using vibration analyzing.

  • 372.
    Ghosh, Rajib
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Rock Mass Characterisation Using Drill Performance Monitoring: Problems, Analysis challenges and Limitations2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In open pit mining, it is important to know as much information as possible about rock masses to be mined for more cost-effective mining operation. In rock engineering perspective, information about rock mass characteristics usually includes hardness of the rock, geological features, fractures, faults, ore contacts, water bearing stratum. The information about large scale rock mass characterisation is still based on traditional methods such as widely spacedcore drillings, geological mapping of exposed walls, analysis of drill cutting, etc but these methods involve uncertainty about rock mass characteristics in uncored areas. In addition, they are expensive and time consuming. The need for more inexpensive methods providing high resolution rock mass characterisation over large mining areas is therefore a priority forfuture mining industry. Measurement While Drilling (MWD) is a well-established drill monitoring technique which provides information about the rock mass in each production hole. This technique is inexpensive and also ensures high resolution information. By using this technique, drill parameters such as penetration rate, feed force, rotation speed, rotation torque and air pressure are recorded during production drilling which can be used to characterise the penetrated rock mass. However, recorded parameters are not only influencedby the variation of rock mass characteristics; they are also affected by the operators, rig control system interventions, bit wear and measurement errors. In order to use this large amount of data on recorded parameters for the purpose of rock mass characterisation, it is necessary to improve our existing understanding about the contribution of all the influencingfactors and to develop the techniques for identifying and minimising the effect of those factors on rock mass characterisation. The focus of this thesis is to evaluate Measurement While Drilling (MWD) system as a tool for large scale rock mass characterisation in rotary blast hole drilling. In this thesis, researchmethods mainly include literature review, data collection, processing, integration, and analysis. The data have been collected from one of the operating open pit mines in Sweden. Multivariate analysis has been performed to assess the wear of the bit. This thesis presents an attempt to evaluate recorded penetration rate and calculated specific energy for rock mass characterisation. Penetration rate is considered as resistance to crushingof the rock while the calculated specific energy is taken as an index of the mechanical efficiency of a rock working process. The analysis shows that horizontal maps of penetration rate and specific energy (hole average) value reflects the variation of rock mass characteristics in a bench. The areas in the bench which have comparatively higher penetration rate and lower specific energy reflect possible interaction between the bit and soft or weak rock orheavily jointed rock. In contrast some areas in the bench have a relatively lower penetration rate and higher specific energy, indicating possible interaction between the bit and hard rock. In addition, using penetration rate and specific energy values between two subsequent benches indicate similar boundaries among the penetrated zones. When plotting specific energy against penetration rate in each bench, a clear inverse non-linear relationship has beenfound between those parameters. This correlation indicates that penetration rate and specific energy can indicate rock mass behaviour. Further, statistical analysis is done to observe the statistical significance of penetration rate and specific energy values among the different penetrated areas in the bench. The results indicate that penetration rate and specific energy can be used for characterizing large scale rock masses. In addition, information about the rockmass in the upper bench can possibly be used in the next bench to improve production planning. However, hole by hole analysis shows penetration rate and specific energy are influenced by bit wear, hole depth variables, flushing system, operator influence, drill control system, etc.Principal Component Analysis (PCA) shows that penetration rate and specific energy reflecting the change of rock mass characteristics basically are not correlated to bit life length. The bit life length seems instead to be well correlated to the operational parameters such as rotation torque, rotation speed and to a minor extent feed force. Conclusions from PCA analysis must be conservative since the explanation rate for the first two components islimited to 56.5%. Further, the analysis shows that recorded penetration rate has a negative trend with the increasing hole depth. The calculated specific energy has a positive trend with the increasing hole depth. This means that recorded parameters are influenced by hole depth variables.The flushing system also influences recorded parameters. The analysis shows that constant air pressure from the collaring point to the end does not give a clear indication of better flushing system as frequent joints and regular water ingression usually cause fluctuation of pressure.Some of the above mentioned problems can be handled to minimise the effect of influencing factors on recorded parameters. The direct effect of bit wear and hole depth dependency can be minimised by generating a horizontal map of recorded data (e.g. penetration rate) over a large area in the bench. Hole depth dependency on recorded parameters can also be neutralised by performing normalisation based on a regression line using simple geometry. Inshort, the effect of influencing factors on the recorded parameters obtained by using the Measurement While Drilling technique can be minimised and, this technique, in turn, can become a useful tool for large scale rock mass characterisation.

  • 373.
    Ghosh, Rajib
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Nyberg, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Zhang, Zongxian
    LKAB, Research & Development, 983 81 Malmberget.
    An investigation of borehole stability in LKAB Malmberget underground mine, Sweden2013Ingår i: Rock Characterisation, Modelling and Engineering Design Methods -: Proceedings of the 3rd ISRM SINOROCK 2013 Symposium / [ed] Xia-Ting Feng; John A. Hudson; Fei Tan, Leiden: CRC Press/Balkema , 2013, s. 747-752Konferensbidrag (Refereegranskat)
    Abstract [en]

    Instability in production blast holes causes poor fragmentation, lower ore recovery, delay in production and higher costs in crushing and grinding. In this investigation, three large ore bodies named Alliansen, Fabian and Vi-Ri were selected. A video camera was used for mapping production blast holessoastofind borehole stability problems. A total of 298 blast holes were filmed. There were eight types of stability problems identified in the blast holes. These are shear zone, loose rock, cave, crack, deformation, stone jammed, spalling and rock breakage. Among these problems, deformation and crack were the most common ones in all the ore bodies. In addition, instability problem in the blast holes were higher around the rings which were blasted last. Further it has been found that the area which is affected by more seismic responses is the same as the one where several boreholes were re-drilled or sheared.

  • 374.
    Ghosh, Rajib
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Schunnesson, Håkan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Evaluation of operating life length of rotary tricone bits using Measurement While Drilling data2016Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 83, s. 41-48Artikel i tidskrift (Refereegranskat)
  • 375.
    Ghosh, Rajib
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Schunnesson, Håkan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Evaluation of Rock Mass Characteristics Using Measurement While Drilling in Boliden Minerals Aitik Copper Mine, Sweden2014Ingår i: Mine Planning and Equipment Selection: Proceedings of the 22nd MPES Conference, Dresden, Germany, 14th - 19th October 2013 / [ed] Carsten Drebenstedt; Raj Singhal, Encyclopedia of Global Archaeology/Springer Verlag, 2014, Vol. 1, s. 81-91Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the mining industry, rock mass characterization is necessary for both short term and long term production planning, but it is a challenge to get detailed information on the geo-mechanical properties of rock mass. Measurement While Drilling (MWD) is a well-established technique to retrieve data on the mechanical response of the rock mass in penetrated horizons. With this data the mining process could be improved regarding drilling cycle time, blast design, loading, hauling, crushing energy and grinding energy for present and underlying benches. This paper presents an attempt to characterize the rock mass in Boliden Minerals Aitik Mine, the largest open pit copper mine of Europe, located in the Northern part of Sweden. Penetration rate and specific energy are used to describe how subsequent benches (upper and lower) are inter-related. The behavior of Specific Energy and Penetration Rate is further evaluated and analyzed.

  • 376.
    Ghosh, Rajib
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Schunnesson, Håkan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    The use of specific energy in rotary drilling: the effect of operational parameters2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    In rotary drilling, specific energy is considered to be an important parameter for defining mechanical efficiency of the rock destruction process. Specific Energy is defined as the energy required to remove one unit of rock. Specific energy is the function of the size of the borehole and various operational parameters including feed force, rotation speed, rotation torque and penetration rate. The harder the material, the higher the specific energy. The traditional method to calculate the specific energy is based on the parameters penetration rate, feed force, torque and rotation speed, that can be provided by Measurement While Drilling (MWD) data from the drill process. In this study, MWD data from an open pit mine in Sweden are used to evaluate data trends among logged parameters and calculated average specific energy. The results show that there is a significant hole length dependency for penetration rate and feed force that affects the predicted specific energy. This may be explained by that the hole cleaning efficiency is reduced with increasing hole length. The analysis shows that the specific energy is over-estimated by 45% in the bottom of an 18 m hole compared to the collaring point. The suggested solution is to use hole average or complement the specific energy calculation with a hole length related component.Keywords: Specific energy, Measurement While Drilling (MWD), Rotary drilling, Geo-mechanical response, Rock-destruction process

  • 377.
    Ghosh, Rajib
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Zhang, Zongxian
    University Centre in Svalbard.
    Nyberg, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Borehole instability in Malmberget Underground Mine2015Ingår i: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 48, nr 4, s. 1731-1736Artikel i tidskrift (Refereegranskat)
  • 378.
    Giessman, Ray
    et al.
    Luleå tekniska universitet.
    Ågren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Structural modifications of A 9 litre diesel engine to decrease noise radiation: A, Text B, Appendices1992Rapport (Övrigt vetenskapligt)
  • 379.
    Glavatskih, Sergei
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Tribotronics facilitates e-maintenance implementation2011Ingår i: Proceedings of the 24th International Congress on Condition Monitoring and Diagnosis Engineering Management: COMADEM 2011 / [ed] Maneesh Singh; Raj B.K.N. Rao; J.P. Liyanage, COMADEM International, 2011, s. 501-506Konferensbidrag (Refereegranskat)
    Abstract [en]

    Our modern society depends to a great extent on the functionality and efficiency of all the mechanical machinery that we see around us and use every day. All these machines involve numerous tribological contacts. A contact between two surfaces that are in motion relative to each other will result in friction and wear.A constant trend towards more compact mechanical systems with higher power densities requires them to operate in increasingly severe conditions, which heavily influence tribological contacts. They, in turn, affect machine efficiency and impose a limit on machine reliability and service life. Present tribological systems are passive, i.e. their performance cannot be tuned on-line. The purpose of tribotronics is to control so-called loss outputs in a tribo-mechanical system: friction, wear, vibration, etc. Such a system includes sensors, a control unit and actuators. A tribotronic system is thus autonomous and self-adjusting. This allows for on-line tuning of the tribological components for the best performance. This paper illustrates how tribotronic systems can facilitate e-maintenance and thus provide foundation for the best maintenance decisions.

  • 380.
    Goebel, Kai
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik. Palo Alto Research Center, Palo Alto, CA, United States.
    Smith, Brian
    NASA Ames Research Center, Moffett Field, CA, United States.
    Bajawa, Anupa
    NASA Ames Research Center, Moffett Field, CA, United States.
    Ethics in prognostics and health management2019Ingår i: International Journal of Prognostics and Health Management, ISSN 2153-2648, E-ISSN 2153-2648, Vol. 10, nr 1, artikel-id 012Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As we are entering an era where intelligent systems are omnipresent and where they also penetrate Prognostics and Health Management (PHM), the discussion of moral machines or ethics in engineering will inevitably engulf PHM as well. This article explores the topic of ethics within the PHM domain: how it is relevant, and how it may be dealt with in a conscientious way. The paper provides a historical perspective on ethics-related developments that resulted in the formulation of engineering ethics codes, regulations, and policies. By virtue of these developments, ethics has already been encapsulated in PHM systems. The specific areas that have traditionally driven ethics considerations include safety and security, and they increasingly include privacy, and environmental protection. During the course of future technology development, innovations will increasingly impact all of these topics. It is argued that consciously embracing these issues will increase the competitive advantage of a PHM technology solution. As a guideline, specific ethics attributes are derived from professional engineering ethics codes, and a path towards insertion into a requirements flowdown is suggested.

  • 381.
    Gong, Liang
    et al.
    State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University.
    Liu, Chengliang
    State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University.
    Li, Yanming
    State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University.
    Fuqing, Yuan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Training feed-forward neural networks using the gradient descent method with the optimal stepsize2012Ingår i: Journal of Computational Information Systems, ISSN 1553-9105, Vol. 8, nr 4, s. 1359-1371Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The most widely used algorithm for training multiplayer feedforward networks, Error BackPropagation (EBP), is an iterative gradient descend algorithm by nature. Variable stepsize is the key to fast convergence of BP networks. A new optimal stepsize algorithm is proposed for accelerating the training process. It modifies the objective function to reduce the computational complexity of the Jacobin and consequently that of Hessian matrices, and hereby directly computes the optimal iterative stepsize. The improved backpropagation algorithm helps alleviating the problem of slow convergence and oscillations. The analysis indicates that the backpropagation with optimal stepsize (BPOS) is more efficient when treating large-scale samples. The numerical experiment results on pattern recognition and function approximation problems show that the proposed algorithm possesses the features of fast convergence and less intensive computational complexity.

  • 382.
    González-González, Asier
    et al.
    Tecnalia Research and Innovation, Industry and Transport Division, Miñano.
    Galar, Diego
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Condition monitoring of wind turbine pitch controller: A maintenance approach2017Ingår i: 15th IMEKO TC10 Workshop on Technical Diagnostics 2017: "Technical Diagnostics in Cyber-Physical Era", 2017, s. 200-206Konferensbidrag (Refereegranskat)
    Abstract [en]

    Due to the wind power capacity energy grow exponential, interest in operation maintenance is increasing. A proper pitch controller must be designed to extend the life cycle of some wind turbine (WT) components such as blades or tower. The pitch control system has two main, but conflicting, objectives. On the one hand, it seeks to maximize the wind energy captured and converted into electrical energy. On the other hand, it seeks to minimize fatigue and mechanical load. Various metrics are proposed to achieve a compromise solution that balances these objectives. A WT of 100 kW is used to validate pitch control strategies

  • 383.
    González-González, Asier
    et al.
    Tecnalia Research and Innovation, Industry and Transport Division, Miñano.
    Jimenez Cortadi, Alberto
    Tecnalia Research and Innovation, Industry and Transport Division, Miñano.
    Galar, Diego
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik. Tecnalia Research and Innovation, Industry and Transport Division, Miñano .
    Ciani, Lorenzo
    University of Florence, Department of Information Engineering.
    Condition Monitoring of Wind Turbine Pitch Controller: A Maintenance Approach2018Ingår i: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 123, s. 80-93Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With the increase of wind power capacity worldwide, researchers are focusing their attention on the operation and maintenance of wind turbines. A proper pitch controller must be designed to extend the life cycle of a wind turbine’s blades and tower. The pitch control system has two main, but conflicting, objectives: to maximize the wind energy captured and converted into electrical energy and to minimize fatigue and mechanical load. Four metrics have been proposed to balance these two objectives. Also, diverse pitch controller strategies are proposed in this paper to evaluate these objectives. This paper proposes a novel metrics approach to achieve the conflicting objectives with a maintenance focus. It uses a 100 kW wind turbine as a case study to simulate the proposed pitch control strategies and evaluate with the metrics proposed. The results are showed in two tables due to two different wind models are used.

  • 384.
    Grane, Camilla
    et al.
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Arbetsvetenskap.
    Normark, Carl Jörgen
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Innovation och Design.
    Lundkvist, Andre
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Alm, Håkan
    Ågren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Broström, Robert
    Volvo Car Corporation, Sverige.
    Davidsson, Staffan
    Volvo Car Corporation.
    Project: EFESOS - Environmental Friendly efficient Enjoyable and Safety Optimized Systems2012Övrigt (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    EFESOS is a Swedish Vehicle HMI (Human Machine Interaction) FFI research project. The overall ambition is to make driving of future cars more environmental friendly, enjoyable and safer by means of optimized systems. The project is managed by Volvo Car Corporation (VCC) and it is a collaboration between VCC and seven other research partners including Luleå University of Technology.

  • 385.
    Granström, Rikard
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    A system and stakeholder approach for the identification of condition information: a case study for the Swedish railway2008Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 222, nr 4, s. 399-412Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of this paper is to identify stakeholders' need for system condition information in order to improve railway punctuality. The paper provides a holistic formulation of maintenance-related punctuality problems within the interface between the contact wire and the pantograph. From the identified problem formulation, the information needed to support the maintenance of technical functions can be identified. The incorporated system and stakeholder perspective adds a dimension to the explanation of what information is needed and why it is needed. The system and stakeholder perspective on the assessment of the information need can serve as decision support when acquiring new condition monitoring technologies. On the basis of the problem formulation, this perspective can also serve as an illustration of how information is to be used to improve punctuality. In order to identify stakeholders' need for system condition information, a failure mode and effects analysis (FMEA) approach was used. The FMEA is complemented with information derived from informal interviews performed with a variety of experts working with issues related to contact wires and pantographs. The applied methodology can be useful for conducting further research studies on other stakeholder and engineering interfaces, such as the wheel-rail interface.

  • 386.
    Granström, Rikard
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Management of condition information from railway punctuality perspectives2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Det ökande behovet av transporter samt en ökande miljömedvetenhet har ökat efterfrågan på och nyttjandet av järnvägstransporter. Det ökande behovet av järnvägstransporter har en signifikant påverkan på viktiga intressentkrav såsom säkerhet, punktlighet, tillförlitlighet, hållbarhet samt kostnader. Detta påverkar i sin tur järnvägens tillämpningar beträffande drift, underhåll och modifieringar. Samtidigt har den pågående avregleringen av järnvägen medfört att nya organisationer har kommit in på järnvägsmarknaden. Följaktligen är punktligheten på järnvägen beroende av en kombination av många krävda funktioner som för närvarande är tillhandahållna av olika intressenter, till exempel infrastrukturhållare, underhållsentreprenörer för infrastruktur och trafikoperatörer. I Sverige är Banverket infrastrukturhållaren.Syftet med denna forskning är att utforska och beskriva hur information beträffande tekniska systems hälsa kan stödja intressenter inom den Svenska järnvägen till att förbättra punktligheten genom ett effektivare underhåll. Fokus ligger på förseningar som är orsakade av frånvaro av krävda infrastrukturfunktioner, även om interaktion med rullande materiel beaktas genom studier av kritiska gränsytor. Tillståndsövervakningsteknologier är fokuserade som den primära applikationen för erhållandet av information om de tekniska systemens hälsa. Därmed är forskningen avsedd att bidra med kunskap om hur tillståndsinformation kan användas för att tillhandahålla krävd transportservice på den svenska järnvägen till en adekvat kostnad för samhället. För att tillfredställa syftet med forskningen har data inhämtats genom dokumentstudier, intervjuer, seminarier, observationer och fältmätningar. Exempel på avhandlad data är; tågförseningsstatistik, felrapportstatistik, inget-fel-funnet-händelser (No-Fault-Found, NFF) samt hjulkrafter. Data har analyserats genom statistiska och analytiska ansatser, till exempel felmod- och effektanalys (FMEA), men även genom teorier relaterade till principal-agent-problemet, Scientific Management och internationella tillförlitlighetsstandarder.Avhandlingen beskriver hur den av en underhållsentreprenör krävda underhållsinsatsen påverkas av det underhåll som trafikoperatörer utför (och vice versa). Detta har en signifikant påverkan på systemets punktlighet samt degraderingen av bundet kapital. Följaktligen så måste effektiva punktlighetsförbättringar genom underhållsinsatser baseras på ett holistiskt järnvägssystemperspektiv, till exempel ett gemensamt beaktande av infrastruktur och rullande materiel. Avhandlingen visar också hur tillståndsinformation kan användas som ett ledningsverktyg för att stimulera uppfyllandet av prestationskrav lagda på järnvägsintressenter. Det är också illustrerat att samma information kan användas för att prediktera och planera nödvändiga förebyggande underhållsåtgärder likväl som att stödja kontinuerlig utveckling av det tekniska systemet. Emellertid, om intressenternas behov inte tillkännages och om inte vederbörliga vetenskapliga utredningar föregår utformandet av krav samt tillståndsövervakningsapplikationerna, är det troligt att de eftersträvansvärda systemprestandaförbättringarna uteblir. Sammanfattningsvis så bidrar avhandlingen med ett möjligt scenario för hur tillståndsinformation kan stödja järnvägsintressenterna till att förbättra punktligheten hos järnvägssystemet genom effektivare underhåll.

  • 387. Granström, Rikard
    et al.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Condition monitoring of railway infrastructure: a case study in northern Sweden2004Ingår i: Proceedings of the 17 international Congress on Condition Monitoring and Diagnostic Engineering Management: COMADEM, Birmingham: COMADEM International, 2004, s. 46-51Konferensbidrag (Refereegranskat)
  • 388. Granström, Rikard
    et al.
    Söderholm, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Condition monitoring of railway wheels and no fault found problems2009Ingår i: International Journal of COMADEM, ISSN 1363-7681, Vol. 12, nr 2, s. 46-53Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Defective railway wheels can cause severe damages to both track and vehicle items, which in worst case can lead to derailments with extensive losses. Wheel impact detection systems are intended to support prevention of railway damages and its related losses, through recognition of wheel defects and generation of alarms. While commissioning of a wheel impact detection system in Sweden, it was revealed that the detection system was reliable as they were not generating any false alarms. However, during operation some of the system's alarms resulted in No Fault Found (NFF) events. Hence an investigation was launched to determine if the cause of the NFF events were false alarms generated by the detection system, or the inability of subsequent manual inspection to replicate the detection system's test result. This paper presents experiences from the verification study and links these to international experiences illustrating how wheel impact detection systems can support continuous assessment of wheel condition and related condition based maintenance efforts.

  • 389. Granström, Rikard
    et al.
    Söderholm, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Punctuality measurements effect on the maintenance process: a study of train delay statistics for the Swedish railway2005Ingår i: Abstracts of the Eighth International Conference "Maintenance & Renewal of Permanent Way; Power & Signalling; Structures & Earthworks": Railway Engineering 2005 / [ed] M.C. Forde, Engineering Technics Press , 2005, s. 22-Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Governmental regulations state that the Swedish national railway administrator Banverket has an overall responsibility for train punctuality, independent of whether train delays are caused by Banverket or the train operating companies. Banverket is responsible for the functioning of the railway system as a whole, but can with own maintenance and reinvestment activities only affect the infrastructure. Conflicts derive from the two stakeholders' different roles and interests. In order to effectively forecast maintenance needs and costs of the infrastructure, Banverket want that the infrastructure's deterioration caused by the rolling stock should be both as small and as predictable as possible. However, the train operating companies look at the same situation from the other point of view, with a focus on their rolling stock. The interrelationship between the two stakeholder roles and their combined maintenance process is complex, since it is difficult to pinpoint the responsibility for the whole transport system and separate assets. One essential approach, in order to monitor low performance linked to responsible stakeholder roles and causes is to follow up the two measures punctuality and train delays. This paper explores the characteristics of existing train delay statistics and describes risks when maintenance efforts and design of incentives for improved railway operation is based on statistics that does not reflect the true root-causes of problems.

  • 390. Granström, Rikard
    et al.
    Söderholm, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Verification and utilization of wheel impact detection systems2006Ingår i: Condition Monitoring and Diagnostic Engineering Management: COMADEM 2006 ; proceedings of the 19th international congress, Luleºa, Sweden, 12 - 15 June 2006 / [ed] Uday Kumar, Luleå: Luleå tekniska universitet, 2006, s. 667-676Konferensbidrag (Refereegranskat)
    Abstract [en]

    Defective rail wheels can cause severe damages to both track and vehicle components, which in worst case can lead to derailments with extensive losses. Wheel impact detection systems are intended to prevent railway damages and its related losses, through recognition of wheel defects and generation of alarms. At commissioning of a wheel impact detection system in Sweden, the commissioning study showed that the system was reliable, without generating any false alarms. However, during operation some of the system's alarms resulted in No Fault Found (NFF) events at subsequent manual inspections. Hence, a verification study was launched in order to determine if the cause of the NFF events were false alarms generated by the system, or the inability of subsequent manual inspection to replicate the system's test result. The verification study was expected to support an exclusion of the manual inspection, which was perceived to be the cause of the NFF events. However, an exclusion of the manual inspection would require the wheel impact detection system to be highly reliable, since it would be the primary foundation for decisions about both operation and maintenance. This study reports on vital experiences from the verification study and links these to experiences from other countries. The experiences highlight the importance of data accuracy and appropriate information management, in order to achieve the potential benefits and avoid the drawbacks of condition monitoring.

  • 391.
    Greberg, Jenny
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Selection of maintenance strategy for mechanized and automated systems using risk analysis1999Ingår i: Proceedings from 5th International Symposium on Mine Mechanization and Automation, Laurentian Univ. Sudbury, CANADA, JUNE 99, 1999Konferensbidrag (Refereegranskat)
    Abstract [en]

    Taking decision concerning selection of maintenance strategy using risk based criteria is essential to develop cost effective maintenance policies for mechanized and automated systems because in this approach technical features (such as reliability & maintainability characteristics) are analyzed considering economic and safety consequences of each alternative at hand. This approach also provides a holistic view of the various decision scenario concerning maintenance strategy where cost consequences of every possible solution can be assessed quantitatively. It is very important that formal reliability and risk assessment form an integral part of the maintenance planning and control process.This paper emphasizes the need of integration of risk analysis methods in all phases of conception, design manufacturing and operation to arrive at the most optimal maintenance policies/strategies for the system under consideration. The paper also discusses various steps involved in risk analysis and concludes that the risk assessment can be used in many activities related to maintenance for arriving at the best decision among the several alternatives available at hand.

  • 392.
    Gupta, Shashank
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Gupta, Piyush
    Inter-University Accelerator Centre, New Delhi.
    Parida, Aditya
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Modeling lean maintenance metric using incidence matrix approach2017Ingår i: International Journal of Systems Assurance Engineering and Management, ISSN 0975-6809, E-ISSN 0976-4348, Vol. 8, nr 4, s. 799-816Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lean Maintenance (LM) enhances organizational profitability by identifying and eliminating maintenance related wastes. There exists no singular metric that measures maintenance related wastes. The paper identifies the LM features and models them using incidence-matrix. LM features are represented by diagonal elements, while its off-diagonal elements represent mutual influences among the LM features. The maintenance system leanness is quantified using the permanent of the matrix. The metric of leanness is proposed to be defined as Lean maintenance index (LMI) and is a ratio of the actual to the ideal values of permanent of actual and ideal maintenance system matrices. A high value of LMI indicates that the maintenance system is operating in a reduced waste scenario with respect to its resources. Among all the LM features, LMI was found to be most sensitive to management support including organizational processes. The results of the methodology are a good guide for managers. The shortcoming of the methodology is that, it relies on values and weights of the inter-relations among the features, which may not be necessarily true and may need further scientific rigor. The proposed methodology of using LMI as a singular metric to judge maintenance efficacy is expected to aid the operation managers in quantifying the maintenance leanness and may help them focus their efforts appropriately. There is no evidence to indicate existence of comprehensive list of LM features that culminate into a singular metric of maintenance productivity. This paper attempts to fill this gap.

  • 393. Gupta, Suprakash
    et al.
    Bhattacharya, Jayanta
    Barabady, Javad
    Tromsø University.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Cost-effective importance measure: a new approach for resource prioritization in a production plant2013Ingår i: International Journal of Quality & Reliability Management, ISSN 0265-671X, E-ISSN 1758-6682, Vol. 30, nr 4, s. 379-386Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose - The aim of this paper is to propose a new measure for criticality analysis of different components of a production plant, called cost-effective importance measure (CEIM) that considers the component’s performance, system structure and economic aspects.Design/methodology/approach - In this work, an explorative literature study covering the concept of importance measure and criticality analysis has been carried out on contemporary literature. The result of the literature study shows that the commonly used importance measures consider the probability of failure of a component and systems structure, and ignore the effect or severity of failures which is an important factor in engineering decision making. It is not clear how to use the concept of importance measure in combination with cost parameter. Hence, a cost-effective importance measure (CEIM) is defined and a case study is presented in order to demonstrate the application of proposed importance measure.Findings - The paper indicates that CEIM useful for the analysis of production plants where reliability and cost of break down are of paramount importance.Research limitations/implications - The concept of CEIM is demonstrated using only a case study of a belt conveyor system in the underground mine of Singareni Coal Company Ltd. However, the concept of CEIM can be used in other area of engineering system.Practical implications - The concept of CEIM can be a handy and effective tool for scheduling of inspection, maintenance and fault diagnosis and these activities can be carried out as per the rank of the components to maximize the benefits in skilled manpower crunch. It also indicates that the upgradation of the production plant’s performance can also be done by improving performance of components with relatively large CEIM values.Originality/value - In this paper, the concept of importance measure is extended to include the effect of severity of failures and cost parameter in the criticality analysis.

  • 394.
    Gupta, Suprakash
    et al.
    Department of Mining Engineering, Indian Institute of Technology (BHU), Varanasi.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    An analytical hierarchy process (AHP)-guided decision model for underground mining method selection2012Ingår i: International Journal of Mining, Reclamation and Environment, ISSN 1748-0930, E-ISSN 1748-0949, Vol. 26, nr 4, s. 324-336Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Decision making in mining, especially the selection of an appropriate stoping method for an ore deposit, is a critical and challenging task owing to its compliance with a set of criteria. The lack of quantitative data and the qualitative nature of the task forces one to adopt an experience- and intuition -based technique like the analytical hierarchy process (AHP). This article examines the application of the AHP for the selection of an appropriate stoping method from a group of alternatives. The developed model has been verified by a number of case studies.

  • 395.
    Gupta, Suprakash
    et al.
    Banaras Hindu University, Varanasi.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Maintenance resource prioritization in a production system using cost-effective importance measure2010Ingår i: Proceedings of the 1st international workshop and congress on eMaintenance, Luleå tekniska universitet, 2010, s. 196-204Konferensbidrag (Refereegranskat)
    Abstract [en]

    For a long time now different importance measures are put to use in reliability literature for importance ranking of events/components, an integral part of reliability analysis. Commonly used importance measures account the probability of occurrence of faults and systems structure, and ignore the effect or severity of failures which is an important factor in engineering decision making. Here a new approach is proposed by evaluating an indicator, called cost-effective indicator that accounts both the component's performance and economic aspects. The costeffective indicator is useful in production systems where operational reliability and cost of break down are of paramount importance. Basic events/components in a fault tree are ranked as per the decreasing value of this indicator to indicate the favourable area for improvement. It is observed in the analysis that cost-effective indicator can be a handy and effective tool for inspection, maintenance and failure detection and these activities can be carried out as per the rank of the components. Upgradation of system's performance can also be done by improving components performance with relatively large values costeffective indicator.

  • 396.
    Gupta, Suprakash
    et al.
    Department of Mining Engineering, Indian Institute of Technology.
    Rahber, Anjum
    Department of Mining Engineering, Indian Institute of Technology.
    Ahmadi, Alireza
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    A vector-dissimilarity-based approach for multi-criteria decision making2013Ingår i: International Journal of Systems Assurance Engineering and Management, ISSN 0975-6809, E-ISSN 0976-4348, Vol. 4, nr 3, s. 249-261Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Decision making in complex environments is influenced by a large number of conflicting and incommensurable factors. It is multidimensional and the influencing factors affect the decision process to varying degrees. The performance measurement of decision alternatives in multi-criteria decision making (MCDM) may be represented as a multidimensional vector in real space. The technique for order preference by similarity to ideal solution (TOPSIS) is a popular MCDM tool. However, sometimes this technique shows its inability to differentiate between decision alternatives. In this paper the limitations of TOPSIS are examined, and an improvement is suggested. The proposed new method uses the vector dissimilarity approach to remove the boundary restrictions and achieve greater sovereignty. The improved method has been demonstrated through a case study of maintenance design for dump trucks deployed in a large surface mine.

  • 397.
    Gustafson, Anna
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Automation of load haul dump machines2011Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Load Haul Dump (LHD) vehicles are used in underground mines to load and transport ore and minerals. They can be manually or automatically operated. With an automatic system, the operator can be taken out of the mine and simultaneously control up to three LHDs, thus increasing both productivity and security for the personnel. There are a number of operation modes available for Load Haul Dump (LHD) vehicles and there are many criteria to consider when choosing the best one. This report fills a gap in the literature by mapping and describing the experiences and present status of the operation and maintenance of both automatic and manual LHDs as well as the existing navigation systems and techniques associated with underground automated loading and transportation.The commercially systems available today for automation of LHDs are supplied by Sandvik, Caterpillar and Atlas Copco. Automation focus have over the years gradually shifted from having fully automated fleets of vehicles to more flexible solutions with semi-automatic LHDs gaining safety as one of the main goals. Several issues must be resolved to maximize the benefits of automation. One is to improve maintenance, as this is crucial for an operation to work smoothly without the waste incurred by unplanned breakdowns.

  • 398.
    Gustafson, Anna
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Automation of Load Haul Dump machines: comparative performance analysis and maintenance modeling2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The Load Haul Dump (LHD) machine and its operating environment create a complex system. Mine productivity depends on the operation of the LHDs and on the mining environment, including fragmentation, size of boulders, navigation techniques etc. Traditional navigation techniques require a lot of infrastructure to accommodate automatic operation. From fully automated fleets of vehicles, the focus of automation has gradually widened to include more flexible solutions, such as semi-automatic LHD machines, with safety as a main goal. The automatic system used for semi-automation is different from that used for fleet automation in that less infrastructure is needed, and the operator controls only one vehicle at a time. A semi-automatic LHD machine can operate in either manual or automatic mode depending on the need and situation. Several issues must be resolved to maximise the benefits of automation. One is to improve the maintenance strategy, especially preventive maintenance, as it is crucial to avoid the loss of time incurred by unplanned breakdowns. Another issue is the complexity of the mining environment; external disturbances such as oversized boulders, road maintenance etc. can throw the entire investment in automation into question.The purpose of this thesis is to explore the maintenance actions connected to automated LHDs as well as the factors influencing the operation of the machine. Research methods include a literature review, unstructured interviews, and data collection and integration. Reliability analysis, fault tree analysis and Markov modeling were performed to comparatively analyse manual and automatic LHDs.This thesis presents an approach to evaluate the performance of manual and semi-automatic LHD machines. It describes the maintenance procedures of automatic LHD machines. It includes a study of the reliability of LHD machines with special attention to automatic operation. It studies the operating environment’s effect on automatically operated LHDs compared to manually operated LHD machines, identifies the external disturbances affecting the automatic operation of LHD machines, and introduces a new way of modeling the maintenance and environmental disturbances to determine the best operation mode for the LHD machine.The analysis shows that the production performance of manual and semi-automatic LHD machines is similar. When it comes to the maintenance performance, hydraulic and electric systems are still the biggest reason for machine downtime but the stops are usually short, which means that LHD machines can start producing relatively soon after failure. However, the automatic LHD machine has more time spent in the workshop for the transmission and engine than the manual LHD machine. The difference in reliability between the machines regarding the engine is not significant. But for the transmission there is a verified difference. One possible reason for the difference in transmission reliability could be engaging/disengaging gears when the machine is in automatic mode.The analysis of the operating environment shows that LHDs suffer from mining related, machine related and/or automatic system related disturbances. Seventy-five percent of the stops causing idle time for LHD machines are related to the operating environment. Better fragmentation of rock to avoid big boulders, better constructed roads to minimise the need for road maintenance etc. are keys to the successful operation of automated LHDs.Fault tree models and reliability block diagrams are effective tools for evaluating the reliability of a system but it can be difficult to include mining related disturbances. Therefore, in this thesis, Markov models are introduced to describe disturbances affecting LHD machines and to identify possible differences between manual and semi-automatic LHDs. A fault tree model can classify and analyse failures but cannot show changes between states; this is something a Markov model can handle. The proposed Markov model built for the application shows that the best mode, from an operational point of view, is semi-automatic operation due to its flexibility handling disturbances of different kinds, especially those that are mining related.

  • 399.
    Gustafson, Anna
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Dependability assurance for automatic load haul dump machines2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Load Haul Dump (LHD) machines are used in underground mines to load and transport ore and minerals. Loading and hauling blasted ore from drawpoint to dumping point constitute a significant portion of the production costs for mining companies. There are a number of operation modes available for LHDs, and there are many criteria to consider when selecting the best one. The use of automated LHDs has been widely discussed due to the potential to increase productivity. The increasing focus on safety and ergonomics also gives an edge to automatically operated loaders over manually operated ones. Mine managers must decide when it is preferable to use manually operated loaders and when to complement or replace these with automatic ones. Automation focus has over the years gradually shifted from having automated fleets of vehicles to the more flexible solutions with semi-automatic LHDs gaining safety as one of the main goals. Several issues must be resolved to maximize the benefits of automation. One is to improve maintenance, and moving from operatorassisted “fail and fix” to planned maintenance. Since the operator is removed from the machine during automatic operation and maintenance staff is not always available on short notice, it is crucial to increase planned maintenance to maximize the investment in automation. Another issue is the complexity of the mining environment, including both the infrastructure and external disturbances like oversized boulders and road maintenance, as these can throw the entire investment in automation into question. The purpose of this thesis is to explore the maintenance actions connected to automated LHDs as well as the factors influencing the dependability of the machine. Research methods include a literature review, interviews, and data collection and analysis. Real time process data, operation and maintenance data have been refined, integrated and aggregated to make a comparative analysis of manual and automatic LHDs. The analysis show that 75% of the stop occasions causing idle time for LHDs relate to the operating environment, 21.5% pertain to machine related issues and 3.5% are related to the infrastructure of the automatic system installed in the mine. There is no difference in what kind of maintenance actions that are taken for manually and automatically operated LHDs, but there is a difference in what type of failures that occurs more frequently for the different operation modes. For automation of LHDs too much unplanned repairs and maintenance work significantly reduces the overall availability and can jeopardize the entire investment in automation. The difference between the semi-automatic and the manual LHD was found to be very small in terms of maintenance cost versus produced number of tons. However, a semi-automated LHD is an optimal machine regarding the ability to adapt to reconfiguring the operation mode to meet demands such as safety, flexibility and productivity.

  • 400.
    Gustafson, Anna
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Galar, Diego
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Schunnesson, Håkan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Heyns, Stephan
    Division of Structural Mechanics, Pretoria.
    Fusion of production, operation and maintenance data for underground mobile mining equipment2012Ingår i: The Ninth International Conference on Condition Monitoring and Machinery Failure Prevention Technologies, 2012, Vol. 2, s. 783-791Konferensbidrag (Refereegranskat)
    Abstract [en]

    For integration purposes, a data collection and distribution system based on the concept of cloud computing could be possible to use for collection of data or information pertaining from various sources of data. From a maintenance point of view, the benefit of cloud computing is that information or data may be collected on the health, variability, performance or utilization of the asset. It is especially useful in data mining where different types of data of different quality must be integrated. This paper discusses the concept and presents one example from the underground mining industry.

567891011 351 - 400 av 1472
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf