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  • 251.
    Block, Jan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Ahmadi, Alireza
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Tyrberg, Tommy
    Saab Aerotech.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Fleet-level Reliability of Multiple Repairable Units: a Parametric Approach using the Power Law Process2014Ingår i: International Journal of Pedagogy, Innovation and New Technologies, ISSN 0973-1318, E-ISSN 2392-0092, Vol. 10, nr 3, s. 239-250Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The application of parametric reliability analysis methods for repairable units, such as Power law process, is quite clear and straightforward for a single repairable unit. However, in practice, the analyst needs to know the reliability characteristics of units at a fleet level. The application of parametric reliability analysis methods at the fleet level, even if it is limited in scope, is quite complex. The aim of this paper is to describe the use of the power law process for multiple repairable units with differing reliability characteristics, to predict the expected number of failures at fleet level. The empirical data used in the paper are based on field data gathered during the operational life of two types of multi repairable units used in the Swedish military aircraft system FPL 37 Viggen from 1977 to 2006. The paper performs the trend test using TTT-based MIL-HDBK-189 and Laplace tests, and assesses the equality of shape-parameters for the intensity function of the power law process for multiple units. Estimation of the scale- and shape-parameters using maximum likelihood estimation is also performed. The parametric approach using power law process was found to yield relatively accurate estimations of number of failures, compared to empirical data

  • 252.
    Block, Jan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Ahmadi, Alireza
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Tyrberg, Tommy
    Logistics Analysis and Fleet Monitoring, Saab Support and Services, Linköping.
    Söderholm, Peter
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Industriell Ekonomi.
    Part-out-based spares provisioning management: A military aviation maintenance case study2014Ingår i: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 20, nr 1, s. 76-95Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose – The purpose of this paper is to present the prerequisites for a part-out-based spares provisioning (PBSP) programme during the phase-out of an aircraft fleet. Furthermore, associated key decision criteria are identified and a framework for the phase-out management process is presented. Design/methodology/approach – Once a decision has been taken to phase-out an aircraft fleet, a number of routines for operations, maintenance and storage are affected and new tasks and functions must be introduced before initiating the actual parting-out process. A decision-making system and a management framework is needed to manage spares planning during the end-of-life phase to ensure availability at minimum cost and to ensure a manageable risk of backorders. Findings – For PBSP programme during the phase-out of an aircraft fleet to succeed and be cost-effective, a number of linked processes, tasks and decisions are required, e.g., those included in the framework proposed in this paper (see Figure 3). A successful implementation of PBSP also requires that these processes and tasks are carried out in a timely manner and that the communications between the concerned parties are prompt, clear and direct. One experience from the studied case is that close and trustful contacts and cooperation between the operator and maintenance provider(s) will greatly facilitate the process. Originality/value – Although the PBSP method is fairly commonly applied within both the military and the civilian sector, somewhat surprisingly very literature has been published on the subject. Indeed, remarkably little has been published on any aspects of maintenance during the end-of-life period.

  • 253.
    Block, Jan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik. Saab Support and Services, Logistics Analysis and Fleet Monitoring, Lifecycle Logistics Division, Linköping, Sweden.
    Ahmadi, Alireza
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Xun, Xiao
    School of Fundamental Sciences, Massey University, Palmerston North, New Zealand.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Spares Provisioning Strategy for Periodically Replaced Units within the Fleet Retirement Period2019Ingår i: International Journal of Systems Assurance Engineering and Management, ISSN 0975-6809, E-ISSN 0976-4348, Vol. 10, nr 3, s. 299-315Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Within aviation enterprises, the process of dismantling an aircraft at the end of its life is referred to as parting-out. Obviously, the asset value of the units and materials parted out from the retired airframes can be considerable. The benchmarked best practice within the aviation industry is to dismantle the retired aircraft and use the parted-out spares to support the remaining fleet or to offer them on the surplus market. Part-out-based spares provisioning (PBSP) has been a major focus of attention for aviation companies. The PBSP approach is a complex task that requires a multidisciplinary and integrated decision-making process. In order to control the stock level and fulfil the decision criteria within PBSP, it is necessary to make decisions on the termination, at specific times, of both the parting-out process and the maintenance and repair actions performed on the units.

    This paper considers repairable units and introduces a computational model to identify the applicable alternatives for repair termination times that will minimize the number of remaining spares at the end of the retirement period, while fulfilling the availability requirement for spares during the PBSP period, at the lowest possible cost.  The feasible alternatives are compared with regard to their respective costs, and the most cost-effective solution is selected. The cost model uses estimates of future maintenance requirements, the turn-around times, the cost of the various maintenance tasks, the future spares consumption, and the estimated salvage of spares from retired aircraft. The output of the model is a set of applicable alternatives which satisfy the availability requirements for spares for the active fleet. The method is illustrated using a case study performed on the Saab-105 training aircraft. 

    The results show that the proposed PBSP approach and computational model provide added value from a sustainability point of view, since the use of existing resources is maximized during the retirement process, through the process of reclaiming units and the applicable maintenance termination alternatives. The implementation of the proposed computational model in a PBSP programme provides a detailed and situation-based overview of the stock level dynamics, and contributes to the spares provisioning process by providing solutions to issues such as obsolescence, last-time buys and cannibalization.

  • 254. Block, Jan
    et al.
    Söderholm, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Tyrberg, Tommy
    Saab Aerotech.
    Changes in items' failure pattern during maintenance: an investigation of the perfect repair assumption2008Ingår i: Annual Reliability and Maintainability Symposium, 2008: RAMS 2008 ; Las Vegas, Nevada, USA, 2008, 28 - 31 Jan, Piscataway, NJ: IEEE Communications Society, 2008, s. 117-122Konferensbidrag (Refereegranskat)
    Abstract [en]

    It is clear that the simple ‘perfect repair' assumption is not immediately applicable to any of the studied types of hardware, i.e. Cooling Turbine, High-Voltage Generator, Hydraulic Accumulator, and Radar Transmitter. Hence, the assumption of ‘perfect repair' needs to be validated for each specific type of item. Assumptions based on the type of physical hardware (e.g. mechanical item or avionics item) are not always trustworthy.Strangely enough the ‘perfect repair' assumption fits best for the Cooling Turbine, which is a highly stressed mechanical item, while the fit is much poorer for the Radar Transmitter, which is an avionics item and for the Hydraulic Accumulator.For the Radar Transmitter the trend seems to be very scattered. For items with a large number of failures early in their life-cycle, repair is ‘better than perfect', i.e. the items become more reliable after repair, presumably by elimination of less reliable subcomponents. However, this effect is not seen for items with few failures early in their life-cycle. For these items ‘perfect repair' initially seems to be a valid model. However, in many cases repair becomes ‘less than perfect' later in the life-cycle. For the Hydraulic Accumulator this trend is even more accentuated and individual items seem to fall into two distinct subpopulations with opposite reliability trends.

  • 255.
    Block, Jan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Tyrberg, T.
    Saab Aerotech.
    Söderholm, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    No Fault Found events during the operational life of military aircraft items2009Ingår i: 8th International Conference on Reliability, Maintainability and Safety, 2009: ICRMS 2009 ; 20 - 24 July 2009, Chengdu, China / [ed] Rui Kang, Piscataway, NJ: IEEE Communications Society, 2009, s. 920-924Konferensbidrag (Refereegranskat)
    Abstract [en]

    No fault found (NFF) events are critical and well-known problems for certain aircraft items. This paper presents a study of these events for repairable items with on-condition maintenance, based on operational data from a military aircraft. Some findings are that: the number of NFF events is influenced by item type and number of repairs; most NFF events are initiated by faults recognized during operation; and different inspections contribute to NFF events. Hence, item design and tests at different operational modes and maintenance echelons should be better aligned to reduce the number of NFF events

  • 256.
    Bo, Lin
    et al.
    The State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing, China.
    Xu, Guanji
    The State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing, China.
    Liu, Xiaofeng
    The State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing, China.
    Lin, Jing
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Bearing Fault Diagnosis Based on Subband Time-Frequency Texture Tensor2019Ingår i: IEEE Access, E-ISSN 2169-3536, Vol. 7, s. 37611-37619Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The texture feature tensor established from a subband time–frequency image (TFI) was extracted and used to identify the fault states of a rolling bearing. The TFI of adaptive optimal-kernel distribution was optimally partitioned into TFI blocks based on the minimum frequency band entropy. The texture features were extracted from the co-occurrence matrix of each TFI block. Based on the order of the segmented frequency bands, the texture feature tensor was constructed using the multidimensional feature vectors from all the blocks; this preserved the inherent characteristic of the TFI structure and avoided the information loss caused by vectorizing multidimensional features. The linear support higher order tensor machine based on the feature tensor was applied to identify the fault states of the rolling bearing.

  • 257.
    Bondarchuk, Alexander
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Rock mass behavior under hydropower embankment dams: results from numerical analyses2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Bridges are an important element of the infrastructure today. The technical competence has reached high levels in most countries and the limits given to a bridge designer are set by economic restrictions rather than technical skill. The ever lasting chase for more economic solutions and procedures includes both a wish for cheaper constructions as well as for a decrease in the following maintenance costs. The roller bearings used in conventional bridges are known to generate high costs both during construction and due to maintenance, and the possibility to remove these bearings and accompanying expansion joints are therefore investigated since several years. In Sweden, the absence of bridges built with integral abutments has made it difficult to test and evaluate this solution. In 2005, an international project called Intab was launched with the explicit aim to look at different solutions possible to use if joints and bearings are excluded. One of the most common discussed problems concerning bridges built without expansion joints is the accommodation of longitudinal elongation due to temperature variations. A bridge built with integral abutments is often supported by piles made of steel or concrete. The longitudinal elongation of the superstructure induces a displacement and a moment in these piles, which in time may cause a fatigue failure. Therefore it is of big interest to look at the amplitude of these strains. Within the Intab project, a pilot object was built in Nordmaling, ~50 km south of Umeå. It is a 40 meter long and 5 meter wide composite bridge with two steel girders and a concrete deck. The steel piles in this bridge is equipped with strain gauges who are used both for longterm and shortterm measurements. The sampled data from longterm measurement is collected on a computer on site, and then downloaded through a traditional modem. The data from the shortterm measurement is sampled and collected immediately during the test. The shortterm test is performed during both summer and winter conditions, and consists of a lorry passing the bridge while different measurements are done. The result from the measurement is also compared to calculations and a 2-D FE-model. It seems that short-term measurements performed during warmer months, May and October, show better agreement with the FE-simulations than the tests performed during the winter. The used FE-model is based on restrictions from Bro 2004. Regarding the long-term measurements, the obtained strain values are not in a range where fatigue can be considered as a severe problem.

  • 258.
    Bondarchuk, Alexander
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Rock mass behavior under hydropower embankment dams with focus on fracture erosion and rock mass stability2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Det finns över 190 kraftverks- och regleringsdammar i Sverige. De flesta dammarna färdigställdes från år 1950 – 1980 och de har nu varit i drift mellan 30 och 60 år. Tid har en dokumenterat negativ effekt på en damms prestanda. Varierande belastningar från vattenreservoaren under drift kan orsaka små förskjutningar av berggrundens sprickzoner. Dessa rörelser bidrar till nedbrytning av dammen och dess reservoar. Ett ökat vattenläckage och en förändrad portrycksfördelning kan leda till initiering av sprickerosion i berggrunden.Det är viktigt att öka förståelsen om berggrundens stabilitet, dess hydrogeologiska egenskaper och respons på belastningar från dammen ur olika tidsperspektiv. Ett angeläget arbete för svensk vattenkraftindustri är att säkerställa de åldrande dammarnas funktion och säkerhet. För att uppdatera och säkerställa det stora antalet dammar enligt nya beräknings- och bedömningsmodeller samt ändrade förutsättningar kommer många dammar att behöva uppdateras, och åtgärdas för att öka dess säkerhet, varför kraftindustrin framöver kommer att göra mycket stora investeringar.Syftet med denna doktorsavhandling är att studera vilka konsekvenser varierande belastningar från damm och reservoar har på berggrundens stabilitet och dess sprickerosion. Jag använder den kopplade hydromekaniska distinkt-element metoden UDEC [Itasca, 2005]. Små förskjutningar längs berggrundens sprickor har studerats över lång tid tillsammans med portrycksfördelning, vattenläckage och vattenflödeshastighet. De numeriska modellerna har en verklig damm som förebild med platsspecifika indata, nämligen Håckren fyllningsdamm i centrala Sverige.Två vinkelräta konceptuella modeller i 2D har utvecklats [Bondarchuk, 2008]. Berggrundens normal- och skjuvförskjutningar analyserades. Resultaten visar att sub-horisontella och subvertikala strukturer kan samverka och ge upphov till vattenläckage under dammen. Beteendet beror på bankningsplanens stupningsriktning. Sprickfrekvensen och de primära spänningarnas storlek och riktning är andra viktiga faktorer för berggrundens beteende.De två konceptuella modellerna har anpassats till en verklig dam genom att använda så mycket platsspecifik data som möjligt. Ny data samlades in med hjälp av vanlig förekommande ingenjörsgeologiska metoder. En god överensstämmelse mellan modellresultat och övervakningsdata indikerar att angreppsättet är robust och kostnadseffektivt även om vissa förbättringar kan genomföras inom givna budgetramar. Små förskjutningar längs berggrundens sprickor har studerats över en period som motsvarar 10 driftår tillsammans med portrycksfördelning, vattenläckage och vattenflödeshastighet. Resultaten visar att berggrunden till största delen är stabil men att små förskjutningar sker och att dessa påverkar distributionen av öppna porer som i sin tur leder till mycket oregelbundna flödesmönster som kan orsaka sprickerosion längs sprickytor och sprickfyllnadsmaterial. I förlängningen kan detta påverka injekteringsskärmens beständighet och därmed berggrundens täthet under dammen.

  • 259. Bondarchuk, Alexander
    et al.
    Ask, Maria
    Dahlström, Lars-Olof
    Nordlund, Erling
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Numerical analysis of rock mass behavior under hydropower embankment dams2009Ingår i: Föredrag vid Bergmekanikdag i Stockholm 9 mars 2009, Stiftelsen bergteknisk forskning - Befo , 2009, s. 149-158Konferensbidrag (Övrigt vetenskapligt)
    Abstract [sv]

    Numeriska analyser av bergmassans beteende under fyllningsdammar för vattenkraftproduktion

  • 260.
    Bondarchuk, Alexander
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ask, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Dahlström, Lars-Olof
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Nordlund, Erling
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Rock mass behavior under hydropower embankment dams: a two-dimensional numerical study2012Ingår i: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 45, nr 5, s. 819-835Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sweden has more than 190 large hydropower dams, of which about 50 are pure embankment dams and over 100 are concrete/embankment dams. This paper presents results from conceptual analyses of the response of typical Swedish rock mass to the construction of a hydropower embankment dam and its first stages of operation. The aim is to identify locations and magnitudes of displacements that are occurring in the rock foundation and grout curtain after construction of the dam, the first filling of its water reservoir, and after one seasonal variation of the water table. Coupled hydro-mechanical analysis was conducted using the two-dimensional distinct element program UDEC. Series of the simulations have been performed and the results show that the first filling of the reservoir and variation of water table induce largest magnitudes of displacement, with the greatest values obtained from the two models with high differential horizontal stresses and smallest spacing of sub-vertical fractures. These results may help identifying the condition of the dam foundation and contribute to the development of proper maintenance measures, which guarantee the safety and functionality of the dam. Additionally, newly developed dams may use these results for the estimation of the possible response of the rock foundation to the construction

  • 261. Bondarchuk, Alexander
    et al.
    Ask, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Dahlström, Lars-Olof
    Nordlund, Erling
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Hydromechanical numerical analysis of rock mass behavior under a Swedish embankment hydropower dam2009Ingår i: Long Term Behaviour of Dams: Proceedings of the 2nd International Conference, 12th-13th October 2009, Graz, Austria / [ed] Erich Bauer; Stephan Semprich; Gerald Zenz, Graz: Verl. der Techn. Univ. Graz , 2009, s. 113-118Konferensbidrag (Refereegranskat)
  • 262.
    Bonnet, Benjamin
    et al.
    Alstom Transport Information Solution.
    Parahy, Marine
    Luleå University of Technology.
    Dersin, Pierre
    Alstom Transport Information Solution.
    Ghodrati, Behzad
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Optimization of maintenance policy based on operational reliability analysis: application to railway switches & crossings2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    The present communication reports on a collaboration between ALSTOM Transport and Luleå Technology University, under the sponsorship of Trafikverket, the Swedish Infrastructure Manager.For 2020, the European Rail Research Advisory Council (ERRAC) has set among other the following objectives [2] : doubling passenger traffic and tripling freight traffic and reducing the life-cycle cost of infrastructure by 30%.This need applies to rail infrastructure in general. Clearly, the highest leverage will be obtained by concentrating the efforts on key cost and availability drivers. For instance, it is reported that switches and crossings (S&C) are one of the subsystems that cause the most delays on Swedish Railways while accounting for at least 13% of maintenance costs. (It is the main reason why we chose to base our study on this subsystem).Intelligent data processing allows to understand the real reliability characteristics of the assets to be maintained. Furthermore simulation and optimisation techniques are applied in order to adapt the maintenance strategy so as to achieve minimum cost while guaranteeing target availability.The first step has been to determine the S&C reliability characteristics based on field data collection. Because field failure data are typically strongly censored, we have developed our own statistics software package to process field failure data, as commercial packages have not been found satisfactory in that respect. The resulting software, named RDAT® (Reliability Data Analysis Tool) has been relied upon for this study: it is especially adapted to statistical failure data analysis. The next step will be to customize the maintenance interval by adapting it to individual switches and crossings behaviour characteristics. In order to predict and optimize life-cycle cost (LCC) and availability, Monte Carlo simulations will be performed with stochastic Petri nets. The failure rates estimated with RDAT® will be used as inputs to the Petri net. Such a model lends itself to maintenance optimization. Indeed, designs of experiments can be used in conjunction with simulations in order to express both LCC and availability as functions of various maintenance-related decision variables (such as preventive maintenance frequency, maintenance efficiency, etc, see [7]).Further improvement could result from applying condition-based maintenance, where preventive maintenance times would no longer be predetermined but rather based on the observed S&C condition, as measured by : number of displacement cycles, current absorbed, vibration intensity during train passage, traffic intensity etc. It is planned to resort to the Watchdog Agent ® software, of Intelligent Maintenance System, to that end [4].

  • 263.
    Borg, Torgny
    Luleå tekniska universitet.
    Prediction of rock failures in mines, with application to the Näsliden mine in northern Sweden1983Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Continous cut and fill mining will cause increased loading of the roof of the stopes in mining operations. The aim of the present work is to predict what mining levels will induce critically large loads in the roof of the stopes in cut and fill mining and in particular the Näsliden Mine, in Northern Sweden. The quasi-static elastic response of rock masses in the Näsliden Mine is predicted in terms of the stresses and strains induced by mining operations, by using the Finite Element Method. Critical stages in the development of failures are identified and defined from observations in the mine. In-situ measurements are also taken from a selected reference stope in the mine, at certain selected stages in a sequence of mining operations. The extension strain criterion of failure is used in our calculations. From our calculations, and the observations from the reference stope, critical levels of mining, for all stopes in the mine, are identified. The predicted response of the rock mass from calculations based on a linearly elastic model is compared with predictions from calculations based on a joint element model. The joint elements are used to simulate weak contact adjacent to the ore body. Both models are evaluated and adjusted by comparisons with in-situ measurements of displacements and stresses. A sensitivity study is used to investigate the effect of variation in rock properties and calculation errors due to numerical discretizations. Full scale strength data are compared with data from uniaxial compression tests conducted in the laboratory. The results obtained with the elastic model and the extension strain criterion show satisfactory agreement with data obtained from the mine. Almost identical results, as far as the prediction of roof failure of stopes in the mine is concerned, are obtained when the joint element model and the Coulomb failure criteria is used in our calculations. Our quantitative prediction of rock failure can be used to determine when rock support is needed or when changes in mining methods should be adopted. Our computational model could also be used to investigate alternative mine layouts.

  • 264.
    Borg, Torgny
    Luleå tekniska universitet.
    Sensitivity aspects of FEM calculations1981Ingår i: Application of rock mechanics to cut and fill mining: proceedings of the Conference on the application of rock mechanics to cut and fill mining, organized by the Departments of rock mechanics and soil mechanics, University of Luleå ... held at the University of Luleå, Sweden, from 1 to 3 June, 1980 / [ed] Ove Stephansson; Michael J. Jones, London: The Institution of Mining and Metallurgy , 1981, s. 213-225Konferensbidrag (Refereegranskat)
  • 265.
    Borg, Torgny
    Luleå tekniska universitet.
    The application of the finite element model of the Näsliden mine to the prediction of future mining conditions1983Ingår i: Mining with backfill: proceedings of the International symposium on mining with backfill, Luleå, 7-9 June 1983 / [ed] Sven Granholm, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1983, s. 309-318Konferensbidrag (Refereegranskat)
  • 266.
    Borg, Torgny
    Luleå tekniska universitet.
    The Näsliden Project: FEM modeling strategies1981Ingår i: Application of rock mechanics to cut and fill mining: proceedings of the Conference on the application of rock mechanics to cut and fill mining, organized by the Departments of rock mechanics and soil mechanics, University of Luleå ... held at the University of Luleå, Sweden, from 1 to 3 June, 1980 / [ed] Ove Stephansson; Michael J. Jones, London: The Institution of Mining and Metallurgy , 1981, s. 196-203Konferensbidrag (Refereegranskat)
  • 267.
    Borg, Torgny
    et al.
    Luleå tekniska universitet.
    Leijon, Bengt
    Luleå tekniska universitet.
    Röshoff, Kennert
    Luleå tekniska universitet.
    Stephansson, Ove
    Luleå tekniska universitet.
    Stability prediction for the Zinkgruvan mine, central Sweden1984Ingår i: Design and performance of underground excavations: ISRM symposium, Cambridge, U.K., 3-6 September, 1984 / [ed] E.T. Brown; J.A. Hudson, London: British Geotechnical Society , 1984, s. 113-121Konferensbidrag (Refereegranskat)
    Abstract [en]

    The geomechanics of the Zinkgruvan Mine are presented. A new approach for performing rock stress measurements in open stopes and drifts was tested. An elastic FEM model and strain failure criteria were applied to predict the future condition of the mine. Limits of the strain failure criteria were based on strain values obtained from the model, observations of rock falls, and major failures in the mine. These limits were used to assess suitable panel height, sill pillar dimensions, and sequence delays for mining parallel ore bodies.

  • 268.
    Borg, Torgny
    et al.
    Luleå tekniska universitet.
    Stephansson, Ove
    Luleå tekniska universitet.
    Modellförsök av sprickutbredningen kring gruvöppningen i Grängesberg1977Rapport (Övrigt vetenskapligt)
  • 269.
    Bro, A.
    Luleå tekniska universitet.
    Three-dimensional styrofoam models of blocky rock masses1991Ingår i: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, ISSN 0148-9062, E-ISSN 1879-2073, Vol. 28, nr 1, s. 109-113Artikel i tidskrift (Refereegranskat)
  • 270.
    Broström, Jeremy
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Nyström, Claes
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Lutningar: Från ritning till verklighet2017Självständigt arbete på grundnivå (yrkesexamen), 5 poäng / 7,5 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta dokument redogör för metoden, resultaten och slutsatserna från enfältundersökning där gång och cykelbanors olika procentuella lutning harundersökts. Detta dokument kan användas som vägledning för att lättare föreställasig hur en procentuell lutning på en väg ser ut i verkligheten. Profilritningar av deinmätta vägarna med tillhörande bilder finns tillgängliga som bilagor. Enprofilritning brukar i de flesta fall inneha olika skalor i vertikal och horisontalledvilket kan ge en felaktig bild om storleken på lutningen ifall personen som granskarritningen inte är medveten om detta. I denna rapport går det att läsa om utfallet avde inmätta vägarna i Luleå med omnejd och skillnaden hur en ritning ser ut därskalan är annorlunda i höjd och plan jämfört med en som inte är det. Lutningarna påde befintliga vägarna har jämförts med Trafikverkets gällande krav och råd för huren väg ska utformas och det fastställs huruvida de har efterföljts eller ej. Efter utfördamätningar och sammanställning av värdena har resultatet jämförts och analyserats.Det framgår tydligt att en lutning som i verkligheten inte ser särskilt brant ut blir iförvrängd skala mer lik en skidbacke än en gångbana.

  • 271.
    Brown, S.M.
    et al.
    Golder Associates.
    Leijon, Bengt A.
    Luleå tekniska universitet.
    Hustrulid, W.A.
    Department of Mining, Coloroado School of Mines.
    Stress distribution within an artificially loaded, jointed block1986Ingår i: Rock stress and rock stress measurements: proceedings of the International Symposium on Rock Stress and Rock Stress Measurements, Stockholm 1-3 September 1986 / [ed] Ove Stephansson, Luleå: CENTEK , 1986, s. 429-439Konferensbidrag (Refereegranskat)
  • 272.
    Burns, K.L
    et al.
    Division of Mineral Physics, C.S.I.R.O.
    Stephansson, Ove
    Wight, A.J.R.
    Geology Department, La Trobe University, Bundoora.
    The Flinders Ranges breccias of South Australia diapirs or décollement?1977Ingår i: Journal of the Geological Society, ISSN 0016-7649, E-ISSN 2041-479X, Vol. 134, nr 3, s. 363-384Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Breccia-cored domes in the Northern Flinders Ranges, South Australia, have been regarded as diapirs analogous to diapiric salt structures in northwestern Germany and the Gulf Coast. It is shown that the core of the Blinman Dome is not intrusive and is not composed of less dense rocks; hence a diapiric process cannot apply. It is suggested that much of the breccia of the core is formed by deformation of a stratigraphic unit composed of interbedded competent and incompetent beds at a Flinders Ranges dgcollernent and results from folding. If this model is correct, the Flinders Ranges structures should occur at ddcollements in other parts of the world.

  • 273.
    Byström, Berth-Ove
    Luleå tekniska universitet.
    Vibrationsundersökningar på SKIP (Malmvagn) vid LKAB:s uppfordningsanläggning i Kiruna1978Rapport (Övrigt vetenskapligt)
  • 274.
    Cai, Baoping
    et al.
    College of Mechanical and Electronic Engineering, China University of Petroleum, Qingdao.
    Huang, Lei
    College of Mechanical and Electronic Engineering, China University of Petroleum, Qingdao.
    Lin, Janet
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Xie, Min
    Department of Systems Engineering and Engineering Management, City University of Hong Kong, Kowloon.
    Bayesian Networks in Fault Diagnosis: some research issues andchallenges2017Ingår i: Proceedings of MPMM 2016: 6th International Conference on Maintenance Performance Measurement and Management, 28 November 2016, Luleå, Sweden / [ed] Diego Galar, Dammika Seneviratne, Luleå: Luleå tekniska universitet, 2017, s. 26-32Konferensbidrag (Refereegranskat)
  • 275.
    Cai, Baoping
    et al.
    China University of Petroleum, Qingdao, Shandong, China.
    Kong, Xiangdi
    China University of Petroleum, Qingdao, Shandong, China.
    Liu, Yonghong
    China University of Petroleum, Qingdao, Shandong, China.
    Lin, Jing
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik. China University of Petroleum, Qingdao, Shandong, China.
    Yuan, Xiaobing
    China University of Petroleum, Qingdao, Shandong, China.
    Xu, Hongqi
    Rongsheng Machinery Manufacture Ltd. of Huabei Oilfield, Hebei, Renqiu, China.
    Ji, Renjie
    China University of Petroleum, Qingdao, Shandong, China.
    Application of Bayesian Networks in Reliability Evaluation2019Ingår i: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 15, nr 4, s. 2146-2157Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Bayesian network (BN) is a powerful model for probabilistic knowledge representation and inference and is increasingly used in the field of reliability evaluation. This paper presents a bibliographic review of BNs that have been proposed for reliability evaluation in the last decades. Studies are classified from the perspective of the objects of reliability evaluation, i.e., hardware, structures, software, and humans. For each classification, the construction and validation of a BN-based reliability model are emphasized. The general procedural steps for BN-based reliability evaluation, including BN structure modeling, BN parameter modeling, BN inference, and model verification and validation, are investigated. Current gaps and challenges in reliability evaluation with BNs are explored, and a few upcoming research directions that are of interest to reliability researchers are identified.

  • 276.
    Calle Cordón, Álvaro
    et al.
    CEMOSA, Spain.
    Jiménez-Redondo, Noemi
    CEMOSA, Spain.
    Morales-Gámiz, J.
    CEMOSA, Spain.
    García-Villena, F. A.
    CEMOSA, Spain.
    Peralta-Escalante, J.
    CEMOSA, Spain.
    Garmabaki, Amir
    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.
    Duarte, Emanuel
    Infraestruturas de Portugal, Lisbon, Portugal.
    Morgado, João
    Infraestruturas de Portugal, Lisbon, Portugal.
    Combined RAMS and LCC analysis in railway and road transport infrastructures2018Ingår i: Proceedings of 7th Transport Research Arena TRA, Vienna, Austria, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Life-cycle cost (LCC) analysis is an assessment technique used to evaluate costs incurred during the life-cycle of a system to help in long term decision making. In railway and road transport infrastructures, costs are subject to numerous uncertainties associated to the operation and maintenance phase. By integrating in the LCC the stochastic nature of failure using Reliability, Maintainability, Availability and Safety (RAMS) analyses, maintenance costs can be more reliably estimated. This paper presents an innovative approach for a combined RAMS&LCC methodology for linear transport infrastructures which has been developed under the H2020 project INFRALERT. Results of the application of such methodology in two real use cases are shown, one for rail and another one for road. The use cases show how the approach is implemented in practice.

  • 277.
    Calle-Cordón, Álvaro
    et al.
    CEMOSA.
    Jiménez-Redondo, Noemi
    CEMOSA.
    Morales-Gámiz, F. J.
    CEMOSA.
    García-Villena, F.A.
    CEMOSA.
    Garmabaki, Amir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Odelius, Johan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Integration of RAMS in LCC analysis for linear transportinfrastructures: A case study for railways2017Ingår i: IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981, E-ISSN 1757-899X, Vol. 236Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Life-cycle cost (LCC) analysis is an economic technique used to assess the totalcosts associated with the lifetime of a system in order to support decision making in long termstrategic planning. For complex systems, such as railway and road infrastructures, the cost ofmaintenance plays an important role in the LCC analysis. Costs associated with maintenanceinterventions can be more reliably estimated by integrating the probabilistic nature of thefailures associated to these interventions in the LCC models. Reliability, Maintainability,Availability and Safety (RAMS) parameters describe the maintenance needs of an asset in aquantitative way by using probabilistic information extracted from registered maintenanceactivities. Therefore, the integration of RAMS in the LCC analysis allows obtaining reliablepredictions of system maintenance costs and the dependencies of these costs with specific costdrivers through sensitivity analyses. This paper presents an innovative approach for acombined RAMS & LCC methodology for railway and road transport infrastructures beingdeveloped under the on-going H2020 project INFRALERT. Such RAMS & LCC analysisprovides relevant probabilistic information to be used for condition and risk-based planning ofmaintenance activities as well as for decision support in long term strategic investmentplanning.

  • 278.
    Camerlenghi, A.
    et al.
    University of Barcelona.
    Ask, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Dugan, B.
    Rice University, Houston.
    Kopf, A.
    MARUM, Bremen.
    Morgan, J.
    Rice University, Houston.
    Suyehiro, K.
    JAMSTEC.
    Urgeles, R.
    University of Barcelona.
    Good reasons for IODP to address submarine geohazards: (with focus on the Mediterranean)2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Following a number of international workshop held in the last few years, this documents synthesise the reasons why future scientific ocean drilling should prioritize geohazards among the scientific objectives. In essence the reasons are the societal relevance, the opportunity to deepen the knowledge of basic geological processes in basin evolution, and the opportunity for technological development. A focus in placed on the Mediterranean Basin because of its high vulnerability to submarine geohazards, and to the known widespread occurrence (in the present and in the recent geological record) of geohazards. Among geohazards of the Mediterranean, a focus is placed on the submarine landslides because of their potential to affect seabed structure and the coastline via the tsunamis they can generate. A list of technological needs and a list of the international workshops is added for reference at the end of the document.

  • 279.
    Candell, Olov
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Development of information support solutions for complex technical systems using eMaintenance2009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Spridningen och användningen av komplexa tekniska system är vanliga i samhället och inom industrin. Många av de komplexa tekniska systemen har stränga krav på säkerhet, tillförlitlighet och kostnader, vilket kräver frekventa uppdateringar och ändringar till följd av ny teknisk utveckling och förändrade funktionskrav. Därför är korrekt, kontextanpassad och aktuell information och informationsstöd avgörande för åtkomst, förvaltning, underhåll och förbättring av de kravställda tjänster som skall tillhandahållas av dessa system. Med tanke på den tekniska utvecklingen och föränderliga företagsklimat, behöver system- och supportleverantörer förbättra utformning och tillhandahållande av lösningar för informationssupport. Detta kan underlättas genom användning av ny och innovativ informations- och kommunikationsteknologi, (IKT) vilka visar sig i form av nya metoder såsom eMaintenance. Det finns dock fortfarande ett behov av metoder och verktyg för utveckling och tillhandahållande av informationssupport genom en integration av affärs- och underhållsprocesser hos både kunder och leverantörer, för att åstadkomma nya affärslösningar såsom Prestandabaserad Logistik (PBL) i de sammanhang som beskrivs ovan. Syftet med denna forskning är därför för att beskriva hur leverantörer av supportlösningar kan utveckla och erbjuda effektiv informationssupport som stöd kopplat till komplicerade tekniska system genom ökad användning av IKT. För att uppnå detta syfte, har en fallstudie inom militär luftfarten utförts. Empiriska data har samlats in genom intervjuer, observationer, arkivstudier, workshops och deltagande forskning. Analysen baseras på befintlig, anpassad och utvecklade teorier, modellbaserade simulering och tillgängliga internationella standarder, i beaktande av ett ramverk för eMaintenance. Resultaten av forskningen är: I) en definition av service-, process- och livscykelorientede eMaintenance lösningar, II) en identifiering av kunders och leverantörers kritiska krav på information och informationssupport III) en identifiering av IKT-relaterade metoder och teknologier lämpade att uppfylla kunder och leverantörers krav på informationssupport, IV) ett tillvägagångssätt för utveckling och tillhandahållande av IKT-baserade lösningar för informationssupport som uppfyller kraven från kunder och leverantörer. Även om dessa resultat erhållits inom kontexten för ett modernt militärflygplan, indikerar resultat erhållna i forskningsprocessen att de i stor utsträckning är allmänna till sin karaktär och kan vara tillämpliga på andra komplexa tekniska system inom processindustrin, elproduktion och transportindustri.

  • 280.
    Candell, Olov
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Karim, Ramin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    eMaintenance: information driven maintenance and support2008Ingår i: Proceedings of the 18th International Conference on Flexible Automation and Intelligent Manufacturing: June 30th - July 2nd, 2008, Skövde, Sweden / [ed] Leo J. de Vin, Skövde: Högskolan i Skövde , 2008, s. 365-372Konferensbidrag (Refereegranskat)
    Abstract [en]

    Today's providers of maintenance and in-service support related to modern aircraft are facing major challenges. A central problem with maintenance and support of aircraft and other complex technical systems is to manage the ever-increasing information flow and system complexity. Both military and commercial operators need to reduce downtime and one way to do this is to speed up the turnaround time for scheduled and unscheduled maintenance, or even better, to reduce the need thereof by implementing condition based maintenance. In order to implement these improved support solutions in a global support environment, eMaintenance is seen as one important building block. eMaintenance includes monitoring, collection, recording and distribution of real-time system health data, maintenance generated data as well as other decision and performance support to all stakeholders independent of organization or geographical location, 24 hours a day, 7 days a week (24/7). eMaintenance has the potential to improve the management and performance of activities related to the maintenance process, and thereby improve the dependability, safety and life cycle cost of critical systems. This is realized through the application of Information & Communication Technology (ICT) throughout the maintenance and support processes, thus integrating built-in tests, external tests at different maintenance echelons, technical information, diagnostics, prognostics and other sources of support information. The purpose of this paper is to present some results from a joint academic and aerospace industry research project, describing requirements and expectations that are important in a global support environment, and also to propose some central components in an eMaintenance framework that integrates maintenance and ICT perspectives.

  • 281.
    Candell, Olov
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Karim, Ramin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Parida, Aditya
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Development of information system for e-maintenance solutions within the aerospace industry2011Ingår i: International Journal of Pedagogy, Innovation and New Technologies, ISSN 0973-1318, E-ISSN 2392-0092, Vol. 7, nr 6, s. 583-592Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Maintenance and support providers to modern aircraft need to manage an increasing amount of information generated by growing system complexity and stakeholder requirements. This introduces new risks in the information management process and makes traditional information services and systems inadequate. However, recent advancements in information and communication technology (ICT) have contributed to the emerging approach of e-Maintenance, which forms an important building block to achieve the desired information logistics. e-Maintenance enables remote and real time maintenance, and includes; collection, monitoring, analysis and distribution of data and information as decision-support to stakeholders of the maintenance and support processes, independent of organization or geographical location, 24 hours a day and 7 days a week (24/7). This paper describes a proposed development of information products by linking theories to practical methodologies and tools (e.g., Quality Function Deployment, QFD) through the development of a demonstrator of a stakeholder-based information product in the context of a modern combat aircraft. Read more about November 2011 P8 - Development of Information System for e-Maintenance Solutions within the Aerospace Industry by www.ijpe-online.com

  • 282.
    Candell, Olov
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Karim, Ramin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Söderholm, Peter
    eMaintenance - information logistics for maintenance support2009Ingår i: Robotics and Computer-Integrated Manufacturing, ISSN 0736-5845, E-ISSN 1879-2537, Vol. 25, nr 6, s. 937-944Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Today‟s providers of maintenance and in-service support related to modern aircraft are facing major challenges. A central problem with Maintenance, Repair and Overhaul (MRO) as well as support of aircraft and other complex technical systems, is to manage the ever-increasing information flow and system complexity. Both military and commercial operators need to reduce aircraft downtime and maintenance man hours. Increased manual information management has the opposite effect, inducing unnecessary cost and affect efficiency negatively. Organisations developing and providing maintenance support products and in-service support does also need to improve the capability to efficiently exploit the increasing amount of digital product information and design data provided together with hardware (HW) and software (SW) products from aircraft manufacturers, sub-system suppliers and Original Equipment Manufacturers (OEM). One way to increase aircraft availability and improve maintenance and support efficiency, is to speed up the turnaround time for scheduled and unscheduled maintenance. The ultimate goal is risk-based utilisation and support, where true Condition-Based Maintenance (CBM) is integrated with current operational requirements and available resources in real-time. This aims at the elimination of all preventive scheduled maintenance based on fixed time intervals and execution of only corrective maintenance that has been predicted and turned into scheduled maintenance facilitated by proper support. To address the challenge of information logistics of digital product data and information within maintenance in-service support, providers need to adapt new methodologies and tools that enable full utilisation of the advantages of digital product data and information in processes and business models, e.g. Service-Oriented Architecture (SOA). In order to implement such improved support solutions in a global support environment, eMaintenance is seen as one important building block. eMaintenance includes monitoring, collection, recording and distribution of real-time system health data, maintenance generated data as well as other decision and performance support information to different stakeholders independent of organization or geographical location, 24 hours a day, 7 days a week (24/7). eMaintenance has the potential to improve the management and performance of activities related to the whole maintenance process, and thereby improve the dependability, safety and Life Cycle Cost (LCC) of critical systems. This can be realized through a coordinated application of Information & Communication Technology (ICT) throughout the maintenance and support processes, thus integrating Built-in Test (BIT) systems, external tests at different maintenance echelons, technical information, diagnostics, prognostics and other sources of support information. The purpose of this paper is to present some results from a joint academic and aerospace industry research project, describing requirements and expectations that are important in a global support environment, and also to propose some central components in an eMaintenance framework that integrates maintenance and ICT perspectives.

  • 283.
    Candell, Olov
    et al.
    Saab Aerotech, Linköping.
    Karim, Ramin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Söderholm, Peter
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Industriell Ekonomi.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Server-oriented information logistics as support to intelligent transport services2010Ingår i: 16th World Congress and Exhibition on Intelligent Transport Systems 2009: 16th ITS World Congress ; Stockholm, Sweden, 21 - 25 September 2009, Curran Associates, Inc., 2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Today‟s society is dependent on an increasing volume of transportation services, which contributes to escalating requirements on economy, dependability, safety, and sustainability of applied transportation systems. When dealing with complex transportation systems with long life cycles, maintenance is fundamental to ensure these critical requirements. The increasing requirements and the technological development have also lead to the emerging approach of eMaintenance, which applies innovative Information & Communication Technology (ICT) to achieve effective information logistics for maintenance purposes. This paper describes the role and development of service-oriented eMaintenance solutions to enable intelligent transportation services and some related research efforts within railway and aviation.

  • 284.
    Candell, Olov
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Söderholm, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    A customer and product support perspective of e-maintenance2006Ingår i: Condition Monitoring and Diagnostic Engineering Management: COMADEM 2006 ; proceedings of the 19th international congress, Luleå, Sweden, 12 - 15 June 2006 / [ed] Uday Kumar, Luleå: Luleå tekniska universitet, 2006, s. 243-252Konferensbidrag (Refereegranskat)
    Abstract [en]

    Today the providers of customer and product support related to military aircraft are facing major challenges. Traditionally, aircraft systems have stringent requirements on safety. In addition to this, the requirements on dependability, costs, and security have increased in importance. These changes, together with an increased diversity of customer requirements in a global utilization environment, add to the complexity of providing appropriate support solutions. The increased customer requirements have also lead to concepts such as total solution selling, or functional products, where the customers are offered availability performance to a fixed price. In order to enable efficient support solutions in a global support environment, e-Maintenance is seen as one important building block. e-Maintenance includes monitoring, collection, and distribution of realtime system health data and information to all stakeholders independent of organizational belonging or geographical location, 24 hours a day, 7 days a week (24-7). The concept of e-Maintenance is realized through the application of Information & Communication Technology (ICT), which integrates built-in tests, external tests at different maintenance echelons, and other sources of support information. The purpose of this paper is to describe important requirements and expectations that a provider of customer and product support related to military aircraft systems has on e-Maintenance in a global support environment.

  • 285.
    Cao, Qinglin
    Luleå tekniska universitet.
    Mining with backfill: a numerical analysis applied to Jinchuan No.2 mine1997Licentiatavhandling, monografi (Övrigt vetenskapligt)
  • 286.
    Cardenas, Abraham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Stiffness Over the Mid-support for a Modified Single Overlap Joint of a Single Bay Trapezoidal Steel Sheet Profile Used in Long Spans2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 287. Carlsson, B.
    et al.
    Nordlund, Erling
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Andersson, Y.
    Lindfors, U.
    The failure process and the acoustic emission of brittle rock under compression1999Ingår i: 9 Congres international de mecanique des roches : comptes-rendus : Paris, France, 1999 / [ed] Gérard Vouille, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1999, s. 569-572Konferensbidrag (Refereegranskat)
  • 288.
    Castaño, Miguel
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Carlson, Johan E.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Rantatalo, Matti
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Risberg, Robert
    Creo Dynamics AB.
    Weston, Miles
    TWI Technology Centre Wales.
    3D Synthetic Aperture Imaging Using a Water-Jet Coupled Large-Aperture Single Transducer2014Konferensbidrag (Övrigt vetenskapligt)
  • 289.
    Castaño, Miguel
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Carlson, Johan E.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Rantatalo, Matti
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Risberg, Robert
    Creo Dynamics AB.
    Weston, Miles
    TWI Technology Centre Wales.
    3D Synthetic Aperture Imaging Using a Water-Jet Coupled Large-Aperture Single Transducer2014Konferensbidrag (Övrigt vetenskapligt)
  • 290.
    Castaño, Miguel
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Carlson, Johan E.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Rantatalo, Matti
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Weston, Miles
    TWI Technology Centre Wales.
    Risberg, Robert
    Creo Dynamics AB.
    3D Synthetic Aperture Imaging Using a Water-Jet Coupled Large Aperture Single Transducer2014Ingår i: 2014 IEEE International Ultrasonics Symposium (IUS 2014): Chicago, Ill. 3-6 September 2014, Piscataway, NJ: IEEE Communications Society, 2014, s. 1372-1375Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a technique for in-situ non-destructive testing of materials with applications in railway crossings. The novelty is in successfully applying the Virtual Source (VS) concept using water jet coupling for a large transducer. By focusing the sound field at the surface of the sample, the water jet probe can be built with a small nozzle opening, limiting the water consumption and making it viable for field applications. The annular geometry of the large transducer ensures the spherical wavefront assumed in the application of the SAFT algorithm, which usually limits the size of the transducer

  • 291.
    Castro, Raul
    et al.
    Julius Kruttschnitt Mineral Research Centre, University of Queensland.
    Trueman, Robert
    Julius Kruttschnitt Mineral Research Centre, University of Queensland.
    Halim, Adrianus
    Julius Kruttschnitt Mineral Research Centre, University of Queensland.
    A study of isolated draw zones in block caving mines by means of a large 3D physical model2007Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 44, nr 6, s. 860-870Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Block caving methods rely on gravity to break and transport large amounts of ore and waste. Despite the importance of gravity flow, there is debate within the literature about the influence that the height of draw, particle size and particle size distribution has on the geometry of extraction and movement zones. This paper presents the results of an experimental programme conducted in the largest three-dimensional (3D) physical model to investigate the mechanisms of flow of cohesionless materials when drawing from a single drawpoint. Experimental results showed that isolated draw zones are mainly influenced by mass drawn and height of draw. Particle size was found to have a slight effect on extraction zones and no significant effect on movement zone width. Particle size composition (wide or narrow distributions) and drawpoint width were found not to have a major role on drawzone geometry. Those conclusions were based on statistical analysis of experimental data to define the controlling parameters in isolated draw. Model theory principles were used to investigate within the physical modelling framework the possibility of directly scaling the geometry of the extraction zones, which indicated that flow zones could be scaled in cohesionless materials under a set of assumptions. A mechanistic model of isolated draw is also postulated from experimental data from observations of stresses and the IMZ’s geometry.

  • 292.
    Chandran, Praneeth
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Rantatalo, Matti
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Odelius, Johan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Lind, Håkan
    Bombardier Transportation, Stockholm, Sweden.
    Famurewa, Stephen M.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Train-based differential eddy current sensor system for rail fastener detection2019Ingår i: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 30, nr 12, artikel-id 125105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One of the crucial components in rail tracks is the rail fastening system, which acts as a means of fixing rails to the sleepers to maintain the track gauge and stability. Manual inspection and 2D visual inspection of fastening systems have predominated over the past two decades. However, both methods have drawbacks when visibility is obscured and are found to be relatively expensive in terms of cost and track possession. The present article presents the concept of a train-based differential eddy current (EC) sensor system for fastener detection. The sensor uses the principle of electromagnetic induction, where an alternating-current-carrying coil is used to create an EC on the rail and other electrically conductive material in the vicinity and a pick-up coil is used to measure the returning field. This paper gives an insight into the theoretical background and application of the proposed differential EC sensor system for the condition monitoring system of rail fasteners and shows experimental results from both laboratory and field measurements. The field measurements were carried out along a heavy-haul railway line in the north of Sweden. Results obtained from both the field measurements and from the lab tests reveal that that the proposed method was able to detect an individual fastening system from a height of 65 mm above the rail. Furthermore, missing clamps within a fastening system are detected by analysing a time domain feature of the measurement signal.

  • 293.
    Changming, Wu
    Luleå tekniska universitet.
    The stress analysis of rock drill percussion systems1989Rapport (Övrigt vetenskapligt)
  • 294.
    Chattopadhyay, G.
    et al.
    Queensland University of Technology.
    Kumar, Saurabh
    Larsson-Kråik, Per-Olof
    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.
    Estimation of parameter for rail degradation2006Ingår 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. 605-612Konferensbidrag (Refereegranskat)
    Abstract [en]

    Rail degradation is a significant problem for rail industries. Wear and fatigue comprises major component of rail degradation. It depends on operational conditions such as train speed, axle load, rail-wheel material type, size and profile, track construction, characteristics of bogie type, Million Gross Tonnes (MGT), curvature, traffic type, weather and environmental conditions. Development of prediction model related to those defects leading to rail breaks and/or rail replacements is vital for economic and safe operation of rail services. Estimation of parameter for failure models is necessary for accurate prediction of expected number of rail defects over a period of time based on Million Gross Tonnes (MGT) traffic, operating conditions and maintenance strategies. This paper focuses on collection and analysis of field data for various defects developed in rail track over a period of time for estimation of parameter for models predicting degradation of rails.

  • 295.
    Chattopadhyay, G.
    et al.
    Faculty of Science Engineering and Health, CQ University, Gladstone Campus.
    Parida, Aditya
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Work integrated blended learning for improvement by asset managers2010Ingår i: 23rd International Congress on Condition Monitoring and Diagnostic Engineering Management: COMADEM 2010; Nara; 28 June 2010 through 2 July 2010 / [ed] Susumu Okumura, Hikone: Sunrise Publishing , 2010, s. 95-101Konferensbidrag (Refereegranskat)
    Abstract [en]

    Work integrated blended learning for asst managers is targeted to the senior engineers and managers. Main purpose of this blended learning is to enhance asset management skills in establishing and managing capital intensive assets and infrastructures. A course in asset management systems in line with PAS55 was developed to reflect the best known practices in asset management, to cover some long-term but little understood issues, and to deliver it in such a way that it was highly effective from the point of view of industries, participants and the delivery team. It includes establishing asset management systems and standards, and taking effective decisions considering asset maintenance costs, risks and performance. This paper is to outline the needs of target audience and provide overview of the work integrated blended course for asset management system for improving decision making by asset managers

  • 296.
    Chattopadhyay, Gopi
    et al.
    Central Queensland University.
    Kumar, Saurabh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Parameter estimation for rail degradation model2009Ingår i: International Journal of Pedagogy, Innovation and New Technologies, ISSN 0973-1318, E-ISSN 2392-0092, Vol. 5, nr 2, s. 119-130Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wear and fatigue in rails are major contributors of rail degradation depending on operational conditions, track, characteristics of bogie type, Million Gross Tonnes (MGT), curvature, traffic type and environmental conditions. Estimation of parameter for failure models is necessary for accurate prediction of expected number of rail defects over a period of time based on MGT of traffic and operating conditions for developing cost effective maintenance strategies. This paper focuses on collection and analysis of field data over a period of time for estimation of parameter for modelling rail life.

  • 297.
    Chen, Guanghui
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Li, Xibing
    School of Resource and Safety Engineering, Central South University, Changsha, Hunan.
    Zhang, Ping
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Nordlund, Erling
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Dong, Longjun
    School of Resource and Safety Engineering, Central South University, Changsha, Hunan.
    Optimization of tunnel support parameters with consideration of seismic wave radiation pattern in the fault-slip burst2017Ingår i: Journal of Mining and Safety Engineering, ISSN 1673-3363, Vol. 34, nr 4, s. 715-722Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As the underground mining extends gradually towards depth, more and more seismic events induced by fault slip occur and cause great damages, which have become a severe potential threat to mining safety. In view of the plane strain problems, through the three dimensional discrete model established, comparison and analysis was carried out between the equivalent calculation of plane strain in 3D model and a 2D discrete model. The results have shown that the research model developed to simulate the propagation of seismic wave in 3D is feasible and applicable. The study of the effect of radiation pattern on seismic propagation revealed and tested the direction of P-and S-wave propagation, which presents high consistency to double couple model of the fault slip. On this basis, the comparison with the design scaling law formulas proposed by Kaiser and associates finds that the existing design scaling law does not totally satisfy the demand of practical engineering. Numerical calculation and analysis with the three dimensional discrete model can further optimize the support parameters, provide better service for system design of mining support, and ensure the safety and high efficiency in mining.

  • 298.
    Chen, Jiayu
    et al.
    Beihang University, Beijing, China.
    Zhou, Dong
    Beihang University, Beijing, China.
    Guo, Ziyue
    Beihang University, Beijing, China.
    Lin, Jing
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    LYU, Chuan
    Beihang University, Beijing, China.
    LU, Chen
    Beihang University, Beijing, China.
    An Active Learning Method Based on Uncertainty and Complexity for Gearbox Fault Diagnosis2019Ingår i: IEEE Access, E-ISSN 2169-3536, Vol. 7, s. 9022-9031Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is crucial to implement an effective and accurate fault diagnosis of a gearbox for mechanical systems. However, being composed of many mechanical parts, a gearbox has a variety of failure modes resulting in the difficulty of accurate fault diagnosis. Moreover, it is easy to obtain raw vibration signals from real gearbox applications, but it requires significant costs to label them, especially for multi-fault modes. These issues challenge the traditional supervised learning methods of fault diagnosis. To solve these problems, we develop an active learning strategy based on uncertainty and complexity. Therefore, a new diagnostic method for a gearbox is proposed based on the present active learning, empirical mode decomposition-singular value decomposition (EMD-SVD) and random forests (RF). First, the EMD-SVD is used to obtain feature vectors from raw signals. Second, the proposed active learning scheme selects the most valuable unlabeled samples, which are then labeled and added to the training data set. Finally, the RF, trained by the new training data, is employed to recognize the fault modes of a gearbox. Two cases are studied based on experimental gearbox fault diagnostic data, and a supervised learning method, as well as other active learning methods, are compared. The results show that the proposed method outperforms the two common types of methods, thus validating its effectiveness and superiority.

  • 299.
    Chen, Jun Fang
    et al.
    Luleå Tekniska Högskola.
    Ouchterlony, Finn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Stephansson, Ove
    Luleå Tekniska Högskola.
    A compre­hensive fracture mechanics model of rock: experimental set up and preliminary results1992Rapport (Övrigt vetenskapligt)
  • 300.
    Chen, Xu-Guang
    et al.
    Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing.
    Wang, Yuan
    Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing.
    Zhang, Qiang-Yong
    Research Center of Geotechnical and Structural Engineering, Shandong University, Jinan.
    Li, Shu-Cai
    Research Center of Geotechnical and Structural Engineering, Shandong University, Jinan.
    Nordlund, Erling
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Analogical model test and theoretical analysis on zonal disintegration based on filed monitoring in deep tunnel2013Ingår i: European Journal of Environmental and Civil Engineering, ISSN 1964-8189, E-ISSN 2116-7214, Vol. 17, nr Suppl. 1, s. 33-52Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Field monitoring carried out in a deep tunnel of the Dingji coal mine in China confirmed the zonal disintegration phenomenon by using the borehole TV. Based on field monitoring, an analogical model test was conducted to research the fracture shape and forming conditions of the rock mass in the Dingji mine. To perform the model test, an analogical material and optical sensor were developed independently. Through the test, the occurrence of zonal disintegration was confirmed and the forming process was monitored. The fracture pattern of zonal disintegration was determined, and the radii of the fractured zones were found to fulfil the relationship of geometric progression. The displacement laws of surrounding rocks during zonal disintegration were obtained and found to be non-monotonic. The test results are in agreement with the field-monitoring results. Through a theory analysis based on fracture mechanics, the mechanism of zonal disintegration was revealed. The fracture zones occur as circles concentric to the cavern periphery, which is the “false face”. Each fracture zone ruptures at the elastic–plastic boundary of surrounding rocks and then coalesces into a circle. The geometric progression ratio was determined; it is related to the mechanical parameters and ground stress of the surrounding rocks and calculated as follows: And the mechanism of the non-monotonic displacement law is revealed; the continuous formation of the “false face” causes the geostress redistribution and crack opening.

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