Ändra sökning
Avgränsa sökresultatet
5678 351 - 360 av 360
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. Wijaya, Andi
    et al.
    Kumar, Rupesh
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Implementing lean principle into mining industry issues and challenges2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    The lean production concept has its origin in automotive industry and is widely used in manufacturing sectors. What makes its applicability in mining difficult is the dynamic nature of mining operations bringing high degree of uncertainty in various unit operations. To reduce the wastage of efforts, one needs to remove uncertainty and predict the process behaviour as correct as possible. Furthermore, to achieve lean approach in mining, the entire mining chain needs to be considered starting from Mine exploration, mine planning, drilling operation, blasting, loading and transportation, ore dressing processes, reclamation, etc. To be lean in mining is not only dependent on mine production systems consisting of equipments and machines but it also depends on quality and reliability of information flow in real time generating action plans. Also, the reliability and maintenance preparedness have major influence on the degree of waste being generated in the process. For example if ore body is not correctly delineated/characterised or drilling operations not performed correctly, wrong charging process and wrong loading process- all may lead to wastage of resources. In fact Lean production has its origin (leans on) in JIT, TQM and TPM. The common denominator of all these philosophies is the human in the process. To improve any process one needs to measure the current status so that any change in current status can be recorded. The paper presents issues and challenges associated with implementation of Lean Principles in Mining industries.

  • 352.
    Wijaya, Andi
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Lundberg, Jan
    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.
    Downtime analysis of a scaling machine2012Ingår i: International Journal of Mining, Reclamation and Environment, ISSN 1748-0930, E-ISSN 1748-0949, Vol. 26, nr 3, s. 244-260Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Scaling machines are identified as one of the major contributors to unplanned downtime. In general, to gain a better understanding of downtime, an analysis of the downtime should be performed. Downtime analysis usually involves a group consisting of many people with various backgrounds. The use of a visualisation method can act as a bridge that eliminates the knowledge gap within the group. The present study has two purposes: firstly to develop a method for visualisation of downtime and secondly to analyse the downtime of a scaling machine utilising the proposed visualisation method. The proposed method provides a visualisation of the downtime estimation and the precision and the uncertainty of the estimation at a given confidence level, as well as the factors influencing the failure. An analysis of the failures of the critical components of the scaling machine has also been conducted and suggestions for improvement have been proposed.

  • 353. Wijaya, Andi
    et al.
    Lundberg, Jan
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Graphical method for visualization of machine's downtime: case study of scaling machine2010Ingår i: Proceedings of the 1st international workshop and congress on eMaintenance, Luleå tekniska universitet, 2010, s. 99-106Konferensbidrag (Refereegranskat)
    Abstract [en]

    Visualization is the foundation for human to understand as human think and create in a graphic world. By nature, maintenance activity is a multi discipline approach, where maintenance engineer should be able to convey their idea to people with various backgrounds. In this situation, visualization is a powerful mode; it can act as a bridge to eliminate the knowledge gap within the group. Knight (2001) developed Jack-knife diagram for visualizing total downtime and factors influencing the failure (failure frequency and mean downtime) in a point estimation. As failure data is a probabilistic in nature, it is important to look not only point estimation but also interval estimation, so the precision and uncertainty of estimation can be identified. This paper proposes a way of visualizing total downtime and factors influencing the failure (failure frequency and mean downtime) in interval estimation. Case study from scaling machines is used for illustration.

  • 354.
    Wijaya, Andi
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Lundberg, Jan
    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.
    Robust-optimum multi-attribute age-based replacement policy2012Ingår i: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 18, nr 3, s. 325-343Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose - A common model in the age-based replacement policy is based on the cost attribute and assumes that the model parameters are known. In practice, the model parameters are estimated from limited historical data, which brings uncertainty into the model. Moreover, minimizing the cost is not the only goal of the maintenance activity. From the decision maker's point of view, the multi-attributes and the uncertainty of the age-based replacement policy are two important aspects to take into consideration in the decision-making process. The purpose of this paper is to propose an approach for a robust-optimum multi-attribute age-based replacement policy. Design/methodology/approach - The proposed approach is based on a combination of the multiattribute age-based replacement policy and robust design problem philosophy. A case study is provided for illustrating the application of the proposed method. Findings - It is found that the proposed approach can determine the interval time for preventive replacement that provides a robust and optimum solution for a multi-attribute age-based replacement policy. Practical implications - The proposed approach can be used by the decision maker in determining a robust-optimum interval time for preventive replacement of multi-attribute age-based replacement, a time interval which is not only optimum, but also robust. Originality/value - This paper presents an approach that simultaneously considers the multi-attributes and the uncertainty in the age-based replacement policy which is, to date, not available

  • 355.
    Xin, Tao
    et al.
    School of Civil Engineering, Beijing Jiaotong University, People’s Republic of China.
    Famurewa, Stephen Mayowa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Gao, Liang
    School of Civil Engineering, Beijing Jiaotong University, People’s Republic of China.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Zhang, Qi
    School of Civil Engineering, Beijing Jiaotong University, People’s Republic of China.
    Grey-system-theory-based model for the prediction of track geometry quality2016Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 230, nr 7, s. 1735-1744Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The quality of track geometry is an important aspect in railway engineering, as it reflects any deviations and thus the actual condition of a track. Monitoring and prediction of a relevant geometry quality parameter provides an opportunity for effective maintenance, thus creating the advantages of extending the life of the asset, reducing maintenance costs and minimizing possession time requirements. Effective maintenance practice requires a good understanding of the behaviour of track structures over time and also prediction of its condition using only a few inputs. This paper presents a grey-system-theory-based model for predicting track irregularity. Three variants of the grey model are presented and their performances are compared with simple linear and exponential models. Regression models and the grey-system-theory-based models are used to obtain the standard deviation of the longitudinal level from a series of geometry inspection data. The overall performances of the models are evaluated in terms of the regression and prediction accuracies, and it is shown that a Fourier series modification of the grey model has the best performance and the minimum error. The contribution of this paper is the creation of a prediction model for track geometry quality, which is essential for planning and scheduling of preventive geometry maintenance.

  • 356. Yi, Huang
    et al.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    The application of Markov chain for studying the operational reliability of the production system at Kiruna mine1993Ingår i: Safety and reliability assessment: an integral approach ; ESREL'93 ; proceedings of the European Safety and Reliability Conference, Munich, Germany, May 10th - 12th 1993 / [ed] Peter Kafka; Josefa Wolf, Amsterdam: Elsevier, 1993, s. 629-636Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper uses a Markov chain to model mining production process and perform reliability, availability and productivity analysis for the LKAB Kiruna mine based on the production performance statistics and the mining production process function analysis

  • 357.
    Zhang, Chuntian
    et al.
    State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University.
    Gao, Yuan
    State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University.
    Yang, Lixing
    State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Gao, Ziyou
    State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University.
    Integrated optimization of train scheduling and maintenance planning on high-speed railway corridors2019Ingår i: Omega: The International Journal of Management Science, ISSN 0305-0483, E-ISSN 1873-5274, Vol. 87, s. 86-104Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Regular maintenances on high-speed railway facilities are performed in every night in China, and during regular maintenances, high-speed railway is not available for the sunset-departure and sunrise-arrival trains (SDSA-trains). In order to reduce the influence of regular maintenances on SDSA-trains, three operation modes are used in practice, which mainly consist of route selections between high-speed railway and normal-speed railway. In this paper, we use some linearization techniques to formulate a mixed integer linear programming (MILP) model to identify the operation modes and the timetable of SDSA-trains, by integrating the time window selection of regular maintenances on high-speed railways. The objective of the model is to minimize the total travel time of SDSA-trains. In the formulation of the model, we introduce state variables to indicate whether a train is running on high-speed railway or not, which makes it conveniently express the selection of operation modes. Based on the real data of Beijing-Guangzhou high-speed and normal-speed railway corridors in China, numerical experiments are carried out to test the proposed model and optimization method.

  • 358. Åhrén, Thomas
    et al.
    Espling, Ulla
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Benchmarking of maintenance process: two case studies from Banverket, Sweden2005Ingår 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. 17-18Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Maintenance is an ongoing process for any system with the purpose to maintain its given function during its lifetime. Since maintenance is an integrated part of the business process, correctly performed maintenance creates increased business values. For this, the management must strive for continuous improvement of maintenance process. One powerful tool for this purpose is benchmarking, eg comparing own performance with best in the class or other high performance organizations and learning what they do to achieve their high level of performance. To make a successful comparison, common performance indicators must be identified and used. Performance indicators can broadly be classified as lead or lag indicators, where lead indicators are performance drivers and lag indicators are outcome measures. Today, there is a lot of performance indicators in use connected to maintenance, covering for example the area of safety, asset condition and asset reliability, maintenance performance and cost control.This paper presents two case studies, the first one deal with benchmarking the maintenance process and where as the second one compares the use of maintenance performance indicators at the Swedish National Rail Administration (Banverket). We discuss some benchmarking results indicating for example how maintenance strategies, i.e. proactive or reactive, impact the maintenance costs and the ratio of unplanned maintenance. We also emphasize that many of the maintenance performance indicators are used by various organizations abroad and thus provide Banverket an opportunity to benchmark its operation internationally to improve its performance. One of the findings in both case studies is that there are two critical parameters that are missing from the list of indicators, namely traffic volume and infrastructure age. An attempt is also made to analyze the impact of chosen indicators, as well as suggesting future maintenance indicators for future benchmarking.

  • 359. Åhrén, Thomas
    et al.
    Liyanage, Jayantha P.
    University of Stavanger.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Maintenance performance measurement study at Banverket2006Ingår 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. 643-649Konferensbidrag (Refereegranskat)
    Abstract [en]

    Maintenance is an ongoing process for any system with the purpose to maintain given function during its lifetime. Since maintenance today is an integral part of the business process, correctly performed maintenance is known to create increased business value. However, still in various business sectors there is a great potential for continuous improvement of the maintenance process. Such improvements can be done by introducing a performance measurement system in a way that it supports the needs of core business processes, focusing on critical-strategic areas determined by the nature of the business, business concerns, and public requirements and regulations. The outcome from the maintenance process can be measured in terms of return on investments (ROI) and health, safety and environment (HSE); driven by such issues as integrity of the plant, adequate competencies, functional internal processes, and good internal and external relationships. This signifies a top-down approach underlying the importance to link the measures for operations and maintenance (i.e. the operations and maintenance performance measurement system) to overall business or organizational objectives by creating a logical cause-and-effect structure. In turn this also can be used as an effective basis to pinpoint those measures that should become ‘key performance indicators'. The final output from this is a link-and-effect model, showing how the operations and maintenance process contributes to overall business objectives. In the last years, a ROI-based framework for operations and maintenance performance measurement systems has been introduced into such industries where maintenance is performed by the company themselves. On the basis of the above, this paper presents how maintenance ROI can be adapted, measured, and linked to overall objectives in governmental appropriated organizations like the Swedish National Rail Administration (Banverket) where maintenance is outsourced.

  • 360.
    Kumar, Uday (Redaktör)
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Karim, Ramin (Redaktör)
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Parida, Aditya (Redaktör)
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Tretten, Phillip (Redaktör)
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Proceedings of the 3rd international workshop and congress on eMaintenance: June 17-18 Luleå, Sweden : eMaintenance, Trends in technologies & methodologies, challenges, possibilites and applications2014Rapport (Refereegranskat)
    Abstract [en]

    Compilation of papers presented in the technical sessions during the eMaintenance 2014.

5678 351 - 360 av 360
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