| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Caretta, Martina Angela, et al.
(författare)
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Water
- 2022
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Ingår i: Climate Change 2022: Impacts, Adaptation and Vulnerability : Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change - Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Kansal, Yogita, et al.
(författare)
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Fixing of Faults and Vulnerabilities via Single Patch
- 2018
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Ingår i: Quality, IT and Business Operations. - Singapore : Springer. - 9789811055768 - 9789811055775 ; , s. 175-190
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Bokkapitel (refereegranskat)abstract
- Users’ demand of reliable software in zero time has made the software development more complex. If software industry fails in fulfilling the demands, then it may undergo big penalties and revenue loss. The developers are pressurized subject to resource constraints provided by the management. Despite such fact, software experiences various validation (testing) processes before its release; faults and vulnerabilities are still left undetected that later lack the quality of the product. The only feasible solution for resisting from the lack after the release of software is patch development. Generally, the patches developed for fixing faults and vulnerabilities are a separate process which requires extra resources that increases the total development cost and time. In this paper, we have proposed a cost framework that solves the problem of optimizing the patch release time with two different approaches. Here, the first approach has considered the release of a single patch that fixes both faults and vulnerabilities jointly. As the severity of vulnerabilities is much higher than the faults, the second approach considered the release of two patches where the first patch has fixed both faults and vulnerabilities jointly and other patch specifically fixed only vulnerabilities. The detailed illustration of the method is presented in the proposed paper. The case study is presented at the end for the validation purpose.
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| 4. |
- Kansal, Yogita, et al.
(författare)
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Prioritizing Vulnerabilities using ANP and Evaluating their Optimal Discovery and Patch Release Time
- 2019
-
Ingår i: International Journal of Mathematics in Operational Research (IJMOR). - : InderScience Publishers. - 1757-5850 .- 1757-5869. ; 14:2, s. 236-267
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Tidskriftsartikel (refereegranskat)abstract
- Method for filtering and identifying a vulnerability class that has high probability of occurrence is needed by organisations to patch their software in a timely manner. In this paper, our first step is to filter the most frequently observed vulnerability type/class through a multi-criteria decision making that involves dependency among various criteria and feedback from various alternatives, known as analytic network process. We will also formulate a cost model to provide a solution to the developers facing high revenue debt because of the occurrence of highly exploited vulnerabilities belonging to the filtered group. The main aim of formulating the cost model is to evaluate the optimal discovery and patch release time such that the total developer's cost could be minimised subject to risk constraints. To illustrate the proposed approach, reported vulnerabilities of Google Chrome with high exploitability have been examined at its source level.
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| 5. |
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| 6. |
- Kumar, Saurabh, et al.
(författare)
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Inspection frequency optimization model for degrading flowlines on an offshore platform
- 2008
-
Ingår i: International Journal of Reliability, Quality and Safety Engineering (IJRQSE). - 0218-5393. ; 15:2, s. 167-180
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Tidskriftsartikel (refereegranskat)abstract
- Many offshore oil and gas installations in the North Sea are approaching the end of their designed lifetimes. Technological improvements and higher oil prices have developed favorable conditions for more oil recovery from these existing installations. However, in most cases, an extended oil production period does not justify investment in new installations. Therefore cost-effective maintenance of the existing platform infrastructure is becoming very important. In this paper, an inspection frequency optimization model has been developed which can be used effectively by the inspection and maintenance personnel in the industry to estimate the number of inspections/optimum preventive maintenance time required for a degrading component at any age or interval in its lifecycle at a minimum total maintenance cost. The model can help in planning inspections and maintenance intervals for different components of the platform infrastructure. The model has been validated by a case study performed on flowlines installed on the top side of an offshore oil and gas platform in the North Sea. Reliability analysis has been carried out to arrive at the best inspection frequency for the flowline segments under study
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| 7. |
- Chattopadhyay, G., et al.
(författare)
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Estimation of parameter for rail degradation
- 2006
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Ingår i: Condition Monitoring and Diagnostic Engineering Management. - Luleå : Luleå tekniska universitet. - 9789163188060 ; , s. 605-612
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 8. |
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| 9. |
- Ghodrati, Behzad, et al.
(författare)
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Product support logistics based on product design characteristics and operating environment
- 2003
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Ingår i: Proceedings of the 38th annual International Logistics Conference and Exhibition. - : Society of Logistics Engineers.
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Konferensbidrag (refereegranskat)abstract
- To improve the reliability, maintainability, and supportability (RMS) of a product, it is necessary to understand the factors influencing the product performance. This factors can be user environment, human (operator) aspects like training, and technical characteristics of the product. The environmental conditions in which the equipment is to be operated, such as temperature, humidity, dust, road conditions, maintenance facilities, maintenance crew training, operators' skill, etc, often have considerable influence directly on the product reliability and indirectly on the product supportability characteristics. Thus operating environment should be seriously considered while dimensioning product support and service delivery performance strategies, since it will have an impact on operational and maintenance cost and service quality to provide product support plan in an optimal condition. Spare parts are classified, as a product support items whose availability is important when planned or unplanned maintenance is to be carried out. Forecasting the required support/spare parts based on technical characteristics and operating environmental conditions of a system, is the one of the best ways for optimizing unplanned stoppages. This paper discusses about product support (required spare part) logistics based on product design characteristics and operating environment both for conventional and functional products.
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| 10. |
- Ghodrati, Behzad, et al.
(författare)
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Product support (spare parts procurement) strategy based on reliability characteristics and geographical location
- 2003
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Ingår i: International Conference on Industrial Logistics. - Vaasa : University of Vaasa. - 952476010X ; , s. 222-235
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Konferensbidrag (refereegranskat)abstract
- Product support, which is also referred to after sale service to the product is important for customer because it increases the availability of the product and it assures the expected function of the product in its operational phase. It gets affected by many factors such as - reliability and maintainability characteristics and geographical location of the product. By highlighting the reliability issues and geographical distribution of product in design and manufacturing phases, the product life cycle cost (LCC) can be optimized. One of the important steps in product design is the decision making for design out maintenance (DOM) and/or designs for maintenance (DFM). The DOM alternative leads to produce high reliable, and vice versa, whereas the DFM assure the similar performance with lower reliability. However, the need for product support and spare parts must be considered in both alternatives. The forecasting of required product support and spare parts based on reliability-maintainability characteristics is one approach for the product LCC optimization. Consequently, spare parts inventory management based on geographical distribution and reliability characteristics of the product can be also used as an alternative. This article describes a method to forecast the spare part requirements based on reliability estimation of the existing product under the influence of the product-operating environment. Subsequently the management of the spare parts inventory will be discussed based on the geographical location and required performance of the product.
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| 11. |
- Jena, Jajati K., et al.
(författare)
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Tunnel QRA : Present and Future Perspectives
- 2019
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Ingår i: System Performance and Management Analytics. - Singapore : Springer. - 9789811073229 - 9789811073236 ; , s. 387-403
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Bokkapitel (refereegranskat)abstract
- With the vision of faster in-land transportation of humans and goods, long tunnels with increasing engineering complexities are being designed, constructed and operated. Such complexities arise due to terrain (network of small tunnels) and requirement of multiple entries and exits (network of traffics leading to non-homogenous behaviour). Increased complexities of such tunnels throw unique challenges for performing QRA for such tunnels, which gets compounded due to handful number of experiments performed in real tunnels, as they are costly and dangerous. A combined approach of CFD modelling of scaled down tunnels could be a relatively less resource intensive solution, nevertheless, associated with its increased uncertainties due to introduction of scaling multiplication factors. Further, with the advent of smart system designs and cheap computational cost, a smart tunnel which manages its own traffic of both dangerous goods carriers and other passenger vehicles based on continuously updated dynamic risk estimate, is not far from reality.
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| 12. |
- Kansal, Yogita, et al.
(författare)
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Effort and coverage dependent vulnerability discovery modeling
- 2018
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Konferensbidrag (refereegranskat)abstract
- In this paper, our primary focus is to propose a generalized mathematical model that can discover potential vulnerabilities on the basis of two key factors: operational effort rate and operational coverage rate. Here, the term operational effort rate refers to the proportion of manpower required to discover vulnerabilities. The operational coverage rate refers to the proportion of software covered by the effort in discovering vulnerabilities. It is assumed that the proposed model follows the Non-Homogeneous Poisson process properties thus different distribution are used to formulate multiple cases. To evaluate the operational effort function, exponential and Weibull distribution are used considering coverage rate either to be a constant or logistic. For model validation, a case study of real commercial software data set has been used
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| 13. |
- Kansal, Yogita, et al.
(författare)
-
User-dependent vulnerability discovery model and its interdisciplinary nature
- 2017
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Ingår i: Life Cycle Reliability and Safety Engineering. - : Springer. - 2520-1352 .- 2520-1360. ; 6:1, s. 23-29
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Tidskriftsartikel (refereegranskat)abstract
- Software Vulnerability is a broad discipline that cannot be controlled only by the technologies. The holistic framework is required that statistically encompasses the entire security issues of IT organizations regardless of individual projects. Earlier researchers have developed several mathematical models that determined the vulnerabilities trend over time. Besides that, the most common victims of the vulnerabilities i.e., the software buyers or users were addressed theoretically without considering their impact on vulnerability discovery modeling. In this research paper, we examined the vulnerability discovery rate on the basis of potential users of commercial software. Here we propose an interdisciplinary model that highlights the relationship between the vulnerability intensity and the number of users of the software. The numerical illustration based on several real data sets is provided to validate the proposed user-dependent vulnerability discovery model.
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| 14. |
- Kour, Ravdeep, 1981-, et al.
(författare)
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Metaverse for Intelligent Asset Management
- 2022
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Ingår i: 2022 International Conference on Maintenance and Intelligent Asset Management (ICMIAM). - : IEEE.
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Konferensbidrag (refereegranskat)
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| 15. |
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| 16. |
- Kumar, Dhananjay, et al.
(författare)
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Reliability analysis of power transmission cables of electric mine loaders using the proportional hazards model
- 1992
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Ingår i: Reliability Engineering & System Safety. - : Elsevier BV. - 0951-8320 .- 1879-0836. ; 37:3, s. 217-222
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Tidskriftsartikel (refereegranskat)abstract
- The proportional hazards model (PHM) is a powerful technique which can be used to investigate the effects of operating environment and the diagnostic variables (covariates) associated with an item on its life length. The effects of two different designs and maintenance on the reliability of a power transmission cable of an electric mine loader is investigated using PHM. The purpose is to illustrate the application of this model in making decisions about selecting the proper material or designing an item to meet the required purpose efficiently. (11 refs.)
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| 17. |
- Kumar, Rajesh, et al.
(författare)
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A conceptual framework for the development of a service delivery strategy for industrial systems and products
- 2004
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Ingår i: Journal of business & industrial marketing. - : Emerald. - 0885-8624 .- 2052-1189. ; 19:5, s. 310-319
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Tidskriftsartikel (refereegranskat)abstract
- Service and product support are increasingly critical elements in the achievement of customer satisfaction and winning new markets. The success of a product support strategy depends on how effectively these services are delivered. The focus of this paper is on performance enhancement through the use of service delivery strategies; critical factors in the marketing of product support and service-related contracts that in turn, foster customer satisfaction, based on industrial systems in a multinational environment Considered in the framework are product design characteristics such as reliability, maintainability, customer's organizational culture and geographical location, for functional as well as conventional products. The paper advocates an increased focus on support to customers within the framework, introduces a modified service gap model and suggests an approach that reduces any gap between expected and required services. An evaluation of service delivery performance is emphasized.
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| 18. |
- Kumar, Rupesh, et al.
(författare)
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Ergonomic and maintainability design issues in mining
- 2009
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Konferensbidrag (refereegranskat)abstract
- Due to confined space and poor illumination in the mine the maintenance activities are difficult to perform which in turn leads to increased down time, cost and injuries. This also influences the productivity of maintenance personnel owing to stresses generated due to increased psychological and physiological demand on them. However, the industry has paid much less attention to the design of the mining machine in initial phase itself with respect to maintainability parameters leading to low productivity, increased maintenance time and increased likelihood of accidents during maintenance and operation of such equipment. The objective of the paper is to present ergonomics factors such as; anthropometery, human sensory, physiological and psychological application in relation to maintainability design issues in mining in order to reduce occupational risk factors and improved maintainability of the mining equipments leading to increased productivity.
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| 19. |
- Kumar, Rupesh, et al.
(författare)
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Ergonomic issues at a railway maintenance workshop
- 2011
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Ingår i: Proceedings of the 24th International Congress on Condition Monitoring and Diagnosis Engineering Management. - : COMADEM International. - 0954130723 ; , s. 1583-1587
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Konferensbidrag (refereegranskat)abstract
- Research on human factors related to railway operation and maintenance has, to an extent, been the neglected branch of transport ergonomics. Despite the numerous reports of ergonomics programs in a variety of industries, no examples of implementing ergonomics interventions in the railway vehicle maintenance workshop have been reported.In this study, a maintenance process at a railway workshop was studied and analyzed with special reference to working posture and maintenance repair time. The working postures of two maintenance personnel were obtained and analyzed using OWAS (Ovako Working Posture Analysis System). From the results, it was clearly indicated that poor working posture was a frequent occurrence during the maintenance activities. It can be concluded that the introduction and implementation of ergonomics principles at the railway maintenance workshop must be considered in order to reduce the poor working postures, maintenance repair time and to improve maintainability and productivity.
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| 20. |
- Kumar, Rajesh, et al.
(författare)
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Implementation and execution of industrial service strategy : a case study from the oil and gas industry
- 2006
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Ingår i: Journal of Quality in Maintenance Engineering. - : Emerald. - 1355-2511 .- 1758-7832. ; 12:2, s. 105-117
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - The purpose of the paper is to discuss the complex issues, obstacles and factors that can have a significant role and influence on the implementation and execution of a performance-based industrial service strategy. Design/methodology/approach - A case study has been performed the oil and gas industry which maps the issues, challenges and opportunities in the process of implementing and executing a performance-based service strategy. Findings - The study identifies differences in practice with respect to conventional as compared to performance-based contracts. Furthermore, performance factors (i.e. cost drivers, performance killers and critical success factors) of the service strategy implementation and execution process are discussed in relation to the oil and gas industry in the North Sea. A performance-based service strategy needs to be upgraded, modified and customized based on performance measurements, as well as needs, wants and preferences of the involved parties during the contract period. Practical implications - The findings and discussions will help service strategy developers, implementers and executors to recognize the importance of a focused service strategy development process for industrial services. Moreover, the paper will guide developers, implementers and executors to decide about factors that need to be considered. Originality/value - The framework discussed can be used to develop a performance-based service strategy. The results of the research will ease the process of understanding and defining the implementation and execution process of a strategy by presenting the possible performance factors in advance.
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| 21. |
- Kumar, Rupesh, et al.
(författare)
-
Improvement of performance of oil and gas production facilities in arctic regions by applying human factors/ergonomic principles at the design phase
- 2009
-
Ingår i: Proceedings of the 20th International Conference on Port and Ocean Engineering under Arctic Conditions.
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Konferensbidrag (refereegranskat)abstract
- The system with a low level of reliability of being deployed in a cold climate often needs special and additional focus on maintainability characteristics in order to achieve the higher level of productivity, system availability and safety. Therefore, the maintainability issue is critical for the successful and effective operation of oil and gas installations in the Arctic environment as the working conditions are made very difficult by low temperature, ice, short period of daylight and lack of support facilities. Furthermore, the maintenance tasks or maintainability in the Arctic region is heavily influenced by the design of the task and the design of the equipment being maintained. The risk of human error in the Arctic environment is very high and about 80% of offshore accidents are caused by humans, with 64% occurring during operations. Morover, human factors/ergonomics is now recognized as a major contributor to operational safety, loss prevention and optimizing system performance in the oil and gas industries. Therefore, the study of human factor and reliability is essential to ensure the safe and reliable operation of industrial plant and systems which involve human operators. Human factors' integration aims to 'design-in' the humans into plant and system design, taking account of their capabilities and limitations. This can lead to significant savings through appropriate manning levels, maintainable plant, reduced rework and user-friendly facilities and systems.The objective of this paper is to explore potential risk factors especially in Arctic conditions with a view to how human factors/ergonomic principles can help to reduce risk factors and increase maintainability of the oil and gas industry. In this paper, the starting point is the offshore oil and gas industry, but the methodology and discussion are to a large extent general and could also be applied in the other industries.
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| 22. |
- Kumar, Rupesh, et al.
(författare)
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Improving maintainability in extreme cold climatic conditions
- 2012
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Ingår i: International Journal of Performability Engineering. - 0973-1318. ; 8:5, s. 563-572
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Tidskriftsartikel (refereegranskat)abstract
- The maintainability issue is critical for the successful and effective operation of any industry in the extreme cold climatic conditions as the working conditions are made very difficult by low temperature, ice, short period of daylight and lack of support facilities. The objective of this paper is to identify potential risk factors in cold conditions and to provide ergonomic guidelines to reduce risk factors and increase maintainability of industries deployed in cold climate
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| 23. |
- Kumar, Rajesh, et al.
(författare)
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Maintenance of machinery : negotiating service contracts in business-to-business marketing
- 2004
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Ingår i: International Journal of Service Industry Management. - : Emerald. - 0956-4233 .- 1758-6704. ; 15:3/4, s. 400-413
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Tidskriftsartikel (refereegranskat)abstract
- As industrial products are becoming more advanced and complex, the role of supporting services needed to exploit a product's function to an agreeable performance is becoming increasingly important To achieve the best performance, industrial customers are entering into service contracts with the original equipment manufacturers (OEM) or independent service providers. This, in turn essentially involves service contract negotiation between OEM/service provider and the client If such contracts are not negotiated carefully, it may lead to conflict and poor system Performance. To achieve a win-win situation for both parties, aspects such as what services to deliver, who is to deliver them, how they are to be delivered and received, and at which performance level, need to be considered in the negotiation process and agreed upon by both the provider and the client. A conceptual framework has been developed for service delivery negotiation process based on review of literature and analysis of results from a survey conducted to study the existing approaches being practiced by the industrial organizations to negotiate a service contract.
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| 24. |
- Kumar, Rajesh, et al.
(författare)
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Service delivery strategy: Trends in Mining Industries
- 2004
-
Ingår i: International Journal of Surface Mining, Reclamation and Environment. - : Informa UK Limited. - 1389-5265 .- 1744-5000. ; 18:4, s. 299-307
-
Tidskriftsartikel (refereegranskat)abstract
- Mine operators are increasingly outsourcing non-core business processes. Often, the maintenace issue is treated as a non-core business by the mining industry. In today's business environment, many industrial operators/users are interested in buying performance rather than physical products. It is a common practice for an original equipment manufacturer (OEM)/supplier of a product to own, operate, maintain, and support his product. Product performance in general is defined in a negotiated agreement. Even in a conventionl product scenario a user/mine operator often prefers to outsource maintenance to OEMs or contractors in order to focus on core business goals. This paper reviews the recent trends in delivery of product support within segments of the mining industry. In this paper, we advocate the adoption of 'solution-selling' and 'total care solutions' into the mining industry. There appears to be a strong likehood that these concepts can benefit the mining industry. Solution selling and total care solutions are seen as applicable to the mining industry because the product/equipment utilised in this industry are specialised and often expensive. The strategies addressed in this paper support a mine operator's option to buy process instead of physical products, and the increasing demand for a total solution.
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| 25. |
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| 26. |
- Kumar, Saurabh, et al.
(författare)
-
A holistic procedure for rail maintenance in Sweden
- 2008
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - 0954-4097 .- 2041-3017. ; 222:4, s. 331-344
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Tidskriftsartikel (refereegranskat)abstract
- The paper discusses a procedure for systematic and holistic (considering most of the factors influencing the rail degradation process) analysis and prediction of rail failures so that rail maintenance can be performed effectively. The current rail maintenance and reporting procedure followed by Banverket (Swedish National Rail Administration) for the Swedish Iron Ore Line is also described. The paper will also discuss on the improvement areas in Banverket's database management system highlighting what to measure and record and the reason behind it.This paper will help the infrastructure managers to better understand the existing rail maintenance procedure, and the improvements which can be incorporated in the existing procedure to make it more effective.
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| 27. |
- Kumar, Saurabh, et al.
(författare)
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An approach for risk assessment of rail defects
- 2010
-
Ingår i: International Journal of Reliability, Quality and Safety Engineering (IJRQSE). - 0218-5393. ; 17:4, s. 291-311
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Tidskriftsartikel (refereegranskat)abstract
- Rail defects appear in a greater variety and frequency due to higher axle loads and increasing traffic density in passenger and freight trains. Many of these rail defects, if left undetected, can develop into rail breaks, which may lead to train derailments. Reduction in the number of such catastrophic events requires huge investments on inspection and maintenance activities. Therefore proper maintenance planning and risk assessment is required to reduce the rail maintenance cost without compromising safety. In this paper, an approach has been developed for risk assessment of rail defects to support the decision-making process during scheduling of rail inspection and grinding frequency, based on the type of defect and its risk of occurring and developing into a rail break. The approach will help in increasing the safety of passengers and rolling stock as well as reducing the overall rail maintenance cost, as it helps in making effective decisions related to inspection frequency (i.e. resource allocation according to the need). The approach is presented with the aid of a case study from the Swedish National Rail Administration (Banverket). Both, quantitative and qualitative analysis technique has been used in this paper to assess the risk of occurrence of a rail defect and its development into a rail break.
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| 28. |
- Kumar, Saurabh, et al.
(författare)
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Issues and challenges with logistics of rail maintenance
- 2006
-
Ingår i: Proceedings of Abstracts and Papers of The Second International Intelligent Logistics Systems Conference 2006. - : Australian Society for Operations Research. - 095962919X ; , s. 16.1-16.9
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Konferensbidrag (refereegranskat)abstract
- Detection and rectification of rail defects are major issues for all rail players around the world. Some of the defects include worn out rails, weld problems, internal defects, corrugations and rolling contact fatigue (RCF) intiated problems such as surface cracks, head checks, squats spalling and shelling. There are challenges to the infrastructure maintenance people with logistics for effective inspection and cost effective recitification decisions. If these issues are addressed properly then inspection and rectification decisions can reduce potential risk of rail breaks and derailments. Inspite of continous efforts by all rail operators around the world to reduce costs, a substantial amount of railway budget is spent on inspection and maintenance of rails. These costs are further increased by inaccurate logistics decisions related to maintenance and inspection personnel, equipment and planning. This paper addresses the issues and challenges related to logistics of rail maintenance with an aim to reduce costs and risk related to rail operations.
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| 29. |
- Kumar, Saurabh, et al.
(författare)
-
Reliability improvement through alternative designs : a case study
- 2007
-
Ingår i: Reliability Engineering & System Safety. - : Elsevier BV. - 0951-8320 .- 1879-0836. ; 92:7, s. 983-991
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Tidskriftsartikel (refereegranskat)abstract
- In today's competitive world, reliability of equipment is extremely important to maintain quality and delivery deadlines. This is achieved by using proper maintenance and design changes for unreliable subsystems and components of a complex system. It is significant to develop a strategy for maintenance, replacement and design changes related to those subsystems and components. An analysis of down time along with causes is essential to identify the unreliable components and subsystems. This paper presents an analysis of failure data of solenoid coils of automatic internal grinding machine used in a bearing manufacturing plant. It analyses various replacement and change of design options such as introduction of pneumatic system in place of electromagnetic solenoids for improvement of reliability of the plunger movement mechanism.
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| 30. |
- Kumar, Uday, et al.
(författare)
-
Preface
- 2016. - 1
-
Ingår i: Current Trends in Reliability, Availability, Maintainability and Safety. - : Springer International Publishing. - 9783319235967 - 9783319235974 ; , s. v-vi
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 31. |
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| 32. |
- Mohan, Gowtham, et al.
(författare)
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Experimental investigation of a novel solar thermal polygeneration plant in United Arab Emirates
- 2016
-
Ingår i: Renewable energy. - : Elsevier BV. - 0960-1481 .- 1879-0682. ; 91, s. 361-373
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Tidskriftsartikel (refereegranskat)abstract
- The demands for space air conditioning and clean drinking water are relatively high in Middle East North African (MENA) countries. A sustainable and innovative approach to meet these demands along with the production of domestic hot water is experimentally investigated in this paper. A novel solar thermal poly-generation (STP) pilot plant is designed and developed for production of chilled water for air conditioning using absorption chiller, clean drinking water with membrane distillation units and domestic hot water by heat recovery. The STP system is developed with a flexibility to operate in four different modes: (i) solar cooling mode (ii) cogeneration of drinking water and domestic hot water (iii) cogeneration of cooling and desalination (iv) trigeneration. Operational flexibility allows consumers to utilize the available energy based on seasonal requirements. Performance of STP system is analyzed during summer months in RAKRIC research facility. Energy flows in STP pilot plant during peak load operations are analyzed for all four modes. STP system with trigeneration mode utilizes 23% more useful energy compared to solar cooling mode, which improves overall efficiency of the plant. Economic benefits of STP with trigeneration mode are evaluated with fuel cost inflation rate of 10%. STP plant has potential payback period of 9.08 years and net cumulative savings of $454,000 based on economic evaluation.
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| 33. |
- Patwardhan, Amit, et al.
(författare)
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A Survey on Predictive Maintenance Through Big Data
- 2016
-
Ingår i: Current Trends in Reliability, Availability, Maintainability and Safety. - Cham : Encyclopedia of Global Archaeology/Springer Verlag. - 9783319235967 - 9783319235974 ; , s. 437-445
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Konferensbidrag (refereegranskat)abstract
- Modern manufacturing systems use thousands of sensors retrieving information at hundreds to thousands of samples per second. The real time data being generated is mostly used for monitoring the processes and the equipment condition. Data processing techniques applied to this data to detect anomalies and thus applying preventive maintenance have been used in the industry. Currently available technologies which were developed during the last two decade for scanning the Internet and providing computational services, working at very large scale can be re-targeted to fulfil the requirements of maintenance of complex systems. These systems can support storage and processing of current as well as historical data. Ability to access and process these large data sets will lead from preventive to predictive maintenance and eventually to smart manufacturing..
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| 34. |
-
Quality, IT and Business Operations : Modeling and Optimization
- 2018
-
Samlingsverk (redaktörskap) (refereegranskat)abstract
- This book discusses action-oriented, concise and easy-to-communicate goals and challenges related to quality, reliability, infocomm technology and business operations. It brings together groundbreaking research in the area of software reliability, e-maintenance and big data analytics, highlighting the importance of maintaining the current growth in information technology (IT) adoption in businesses, while at the same time proposing process innovations to ensure sustainable development in the immediate future. In its thirty-seven chapters, it covers various areas of e-maintenance solutions, software architectures, patching problems in software reliability, preventive maintenance, industrial big data and reliability applications in electric power systems.The book reviews the ways in which countries currently attempt to resolve the conflicts and opportunities related to quality, reliability, IT and business operations, and proposes that internationally coordinated research plans are essential for effective and sustainable development, with research being most effective when it uses evidence-based decision-making frameworks resulting in clear management objectives, and is organized within adaptive management frameworks. Written by leading experts, the book is of interest to researchers, academicians, practitioners and policy makers alike who are working towards the common goal of making business operations more effective and sustainable.
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| 35. |
- Singh, Sarbjeet, et al.
(författare)
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Applying human factor analysis tools to a railway brake and wheel maintenance facility
- 2015
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Ingår i: Journal of Quality in Maintenance Engineering. - 1355-2511 .- 1758-7832. ; 21:1, s. 89-99
-
Tidskriftsartikel (refereegranskat)abstract
- PurposeThis paper demonstrates three techniques to extract human factor information from specific railway maintenance tasks. It describes the techniques and shows how these tools can be applied to identify improvements in maintenance practices and workflow. Design/methodology/approachThree case studies were conducted on single group of technicians (N=19) at a railway maintenance workshop in Luleå, Sweden. Case study I examined the posture of the technicians while they were changing the brake shoes of freight wagons; the study employed the Standard Nordic Questionnaire and a videotape using the Ovako Working Posture Analysis System (OWAS). Case study II looked at maintenance repair times required to change the wheel axle on freight wagons at the workshop. A video filming method suggested by the European Agency for Safety and Health at Work was used to measure actual maintenance time. Finally, case study III considered the technicians’ (N=19) perception of work demands, their control over the work and their social support while performing maintenance tasks (brake shoe and wheel axle maintenance); to this end, the case study used a demand control support questionnaire. FindingsIn the first case study, the Standard Nordic Questionnaire confirmed that technicians at this particular railway vehicle maintenance workshop suffer from back and shoulder pain. The Ovako Working Posture Analysis showed that 21% of the working time required to fit the brake wedge and cotter pin fits into two OWAS categories: category 3, where “change is required as soon as possible,” and category 4, where “change is required immediately”. Problems stem from poor workplace layout, incorrect posture and inaccessibility of tools and components. In the second study, the video analysis indicated that the working time to change the wheel axle of a freight wagon is greatly affected by poor workplace layout. The third case study showed that the technicians have lower “psychological demands” (mean=13), “higher control over work” (mean= 16) and “high social support” (mean= 22).Practical implicationsThe objective of this study was to apply knowledge about human factors to the functional relationships between maintenance personnel, tasks and the working environment to improve safety. If the workplace layout, working posture, maintenance manuals and accessibility of tools are poorly planned, maintenance performance can be adversely affected. The results of this study should assist maintenance management to design new policies and guidelines for improving the work environment.Originality/valueThree case studies were conducted at a railway maintenance workshop in Luleå, Sweden, to collect data on how human factors affect various railway maintenance tasks.
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| 36. |
- Singh, Sarbjeet, et al.
(författare)
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Modelling factors affecting human operator failure probability in railway maintenance tasks : an ISM-based analysis
- 2015
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Ingår i: International Journal of Systems Assurance Engineering and Management. - : Springer Science and Business Media LLC. - 0975-6809 .- 0976-4348. ; 6:2, s. 129-138
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the factors affecting human operators’ probability of failure when performing railway maintenance tasks. The objective is to understand the interaction of the various factors and to identify driving and dependent factors. The factors are identified through a survey of the literature and ranked using a Likert scale. The reliability of measures is pretested by applying Cronbach’s alpha coefficient to responses to the questionnaire given to maintenance personnel. An interpretive structural model is presented, and factors are classified using matrice d’impacts croises-multiplication appliquéà un classement (MICMAC). The research may help maintenance management understand the interaction of factors affecting human failure probability in railway maintenance and help management devise policies and guidelines for railway maintenance related tasks.
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| 37. |
- Thaduri, Adithya, et al.
(författare)
-
Analytics for Maintenance of Transportation in Smart Cities
- 2018
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Ingår i: Quality, IT and Business Operations. - Singapore : Springer. - 9789811055768 - 9789811055775 ; , s. 81-91
-
Bokkapitel (refereegranskat)abstract
- Cities typically face a wide range of management and maintenance problems. They are complex environments in which digital technologies are more and more pervasive; this digitization of urban environment provided a scope for enriched environment that has capability for data-driven methods. The connections and exchange of data increase and the need for data acquisition, processing, and management become an extremely important added value to the community. The inclusion of digitization and incorporation of predictive analytics provide a base for a sustainable smart city. This work considers an overview of different challenges that utilizes different technologies within a smart city maintenance with respect to transportation. A conceptual framework is proposed to handle the generated data for decision for control, monitoring, fault diagnosis, and maintenance of more and more complex systems.
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| 38. |
- Thaduri, Adithya, et al.
(författare)
-
Comparison of failure characteristics of different electronic technologies by using modified physics-of-failure approach
- 2015
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Ingår i: International Journal of Systems Assurance Engineering and Management. - : Springer Science and Business Media LLC. - 0975-6809 .- 0976-4348. ; 6:2, s. 198-205
-
Tidskriftsartikel (refereegranskat)abstract
- The electronic components are used in several safety and maintenance systems that require accurate reliability prediction for higher availability. The traditional reliability prediction methods that draw on standard handbooks such as MIL-HDBK 217F, Telcordia, CNET etc., are inappropriate to determine the reliability indices of these components due to empirical methods does not comply with operating life cycle and technology advancements. The progressive reliability prediction methodology, the physics-of-failure (PoF), emphasizes the root cause of failure, failure analysis, and failure mechanisms based on the analysis of parameter characteristics. However, there is a limitation: it is sometimes difficult to obtain manufacturer’s details for failure analysis and quality information. Several statistical and probability modeling methods can be performed on the experimental data of these components to measure the time to failure. These experiments can be conducted using the accelerated-testing of dominant stress parameters such as voltage, current, temperature, radiation etc. In this paper, the combination of qualitative data from PoF approach and quantitative data from the statistical analysis is used to create a modified physics-of-failure approach. The critical electronic components used in certain safety systems from different technologies are chosen for reliability prediction: optocoupler, constant fraction discriminator, BJT transistor, voltage comparator, voltage follower and instrumentation amplifier is studied. The failure characteristics of each of the technologies are studied and compared according to operating conditions
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| 39. |
- Thaduri, Adithya, et al.
(författare)
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Comparison of reliability prediction methods using life cycle cost analysis
- 2013
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Ingår i: Proceedings on the 59th Annual Reliability and Maintainability Symopsium (RAMS 2013). - 9781467347099 - 9781467347105
-
Konferensbidrag (refereegranskat)abstract
- In this paper, it was discussed on the several reliability prediction models for electronic components and comparison of these methods was also illustrated. A combined methodology for comparing the cost incurring for prediction was designed and implemented with an instrumentation amplifier and a BJT transistor. By using the physics of failure approach, the dominant stress parameters were selected on basis of research study and were subjected to both instrumentation amplifier and BJT transistor. The procedure was implemented using the methodology specified in this paper and modeled the performance parameters accordingly. From the prescribed failure criteria, mean time to failure was calculated for both the components. Similarly, using 217 plus reliability prediction book, MTTF was also calculated and compared with the prediction using physics of failure. Then, the costing implications of both the components were discussed and compared them. From the results, it was concluded that for critical components like instrumentation amplifier though the initial cost of physics of failure prediction is too high, the total cost incurred including the penalty costs were lower than that of traditional reliability prediction method. But for non-critical components like BJT transistor, the total cost of physics of failure approach was too higher than traditional approach and hence traditional approach was much efficient. Several other factors were also compared for both reliability prediction methods.
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| 40. |
- Thaduri, Adithya, et al.
(författare)
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Computational intelligence framework for context-aware decision making
- 2017
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Ingår i: International Journal of Systems Assurance Engineering and Management. - : Springer. - 0975-6809 .- 0976-4348. ; 8:Supp. 4, s. 2146-2157
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Tidskriftsartikel (refereegranskat)abstract
- Learning of context-aware systems is necessary in building up knowledge on the characteristics of the environment to provide efficient decision making within multi-objective requirements. As the industrial systems becomes complex day-by-day, intelligent machine learning techniques need to be implemented at respective context-aware situations to facilitate recommendations using soft computing methods based on dynamic user specifications. In this paper, a framework is designed for a meta-database that is generated by contextual information of several peers with what-if conditions and rule-based approaches and thus by provide decision making utilizing several existing soft computing algorithms.
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| 41. |
- Thaduri, Adithya, et al.
(författare)
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Context-Based Maintenance and Repair Shop Suggestion for a Moving Vehicle
- 2016
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Ingår i: Current Trends in Reliability, Availability, Maintainability and Safety. - Cham : Encyclopedia of Global Archaeology/Springer Verlag. - 9783319235967 - 9783319235974 ; , s. 67-81
-
Konferensbidrag (refereegranskat)abstract
- Maintenance of moving vehicles is quite challenging because they may disrupt the normal flow of transportation due to unexpected breakdowns, slowdowns and stoppages. In order to avoid stoppages and to minimize the downtime, maintenance and condition monitoring systems must be optimized. On one hand the condition monitoring on board should provide automatic failure detection, identification and localization together with a prognostic of the future failures. On the other hand maintenance logistics and product supportability must be also optimized since the onboard system should provide a suggestion of a repair shop that depends on location, cost and availability of spare parts, technicians’ skills and queuing time for repairs. However the vehicles are independent assets interacting among them within the traffic system and also interacting with the infrastructure (roads, rails etc.) seriously affected by weather, maintenance of infra, regulations etc. Therefore the proposed solution is to equip the vehicles with a context-aware system that monitors the condition and maintenance schedules of parts and alarm the driver of the parts that are in near to repair cycle. This system will perform risk analysis and will communicate with the cloud propose a decision of selection of repair shop on the location and path of vehicle depending on weather, road and traffic, cost and availability of spare parts at respective repair shops based on risk assessment and prediction. The information contained in the cloud will also communicate the workshop that will book time slot and block the necessary spare parts for the coming vehicle minimizing waiting time. This mechanism will help in reducing unexpected stoppages, vehicle degradation and efficient spare parts management combining in a successful way the workload of the workshops from both natural sources, the time based inspections and repairs together with the reactive maintenance coming from unexpected breakdown
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| 42. |
- Thaduri, Adithya, et al.
(författare)
-
Failure modeling of constant fraction discriminator using physics of failure approach
- 2013
-
Ingår i: International Journal of Reliability, Quality and Safety Engineering (IJRQSE). - 0218-5393. ; 20:3
-
Tidskriftsartikel (refereegranskat)abstract
- Due to several advancements in the technology trends in electronics, the reliability prediction by the constant failure methods and standards no longer provide accurate time to failure. The physics of failure methodology provides a detailed insight on the operation, failure point location and causes of failure for old, existing and newly developed components with consideration of failure mechanisms. Since safety is a major criteria for the nuclear industries, the failure modeling of advanced custom made critical components that exists on signal conditioning module are need to be studied with higher confidence. One of the components, constant fraction discriminator, is the critical part at which the failure phenomenon and modeling by regression is studied in this paper using physics of failure methodology.
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| 43. |
- Thaduri, Adithya, et al.
(författare)
-
Maintenance of Railway Infrastructure Using Cyber-Physical Systems
- 2020
-
Ingår i: Decision Analytics Applications in Industry. - Singapore : Springer. ; , s. 521-540
-
Bokkapitel (refereegranskat)abstract
- Cyber-physical systems (CPS) facilitate the recent advancements in manufacturing to make it a comprehensive system that incorporates computational intelligence, communication technologies, context-awareness and data analytics. The potential of CPS is not only confined to manufacturing but are also applicable to other complex infrastructure systems that necessitate improved life cycle and asset management system. The maintenance of such a system of systems necessitates a holistic view of the infrastructure for effective decision support methodologies. This paper discusses infrastructure maintenance from the viewpoint of life cycle management within the structure of cyber-physical systems. This paper also discusses several assisting technologies to support the development of CP. In addition, some use cases are provided from the literature and based on their experience, a CPS framework is developed for Swedish Railway Infrastructure. This CPS system also enables the development of Digital Twin for Railways.
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| 44. |
- Thaduri, Adithya, et al.
(författare)
-
Process Mining for Maintenance Decision Support
- 2019
-
Ingår i: System Performance and Management Analytics. - Singapore : Springer. - 9789811073229 - 9789811073236 ; , s. 279-293
-
Bokkapitel (refereegranskat)abstract
- In carrying out maintenance actions, there are several processes running simultaneously among different assets, stakeholders, and resources. Due to the complexity of maintenance process in general, there will be several bottlenecks for carrying out actions that lead to reduction in maintenance efficiency, increase in unnecessary costs and a hindrance to operations. One of the tools that is emerging to solve the above issues is the use Process Mining tools and models. Process mining is attaining significance for solving specific problems related to process such as classification, clustering, discovery of process, prediction of bottlenecks, developing of process workflow, etc. The main objective of this paper is to utilize the concept of process mining to map and comprehend a set of maintenance reports mainly repair or replacement from some lines on the Swedish railway network. To attain the above objective, the reports were processed to extract out time related maintenance parameters such as administrative, logistic and repair times. Bottlenecks are identified in the maintenance process and this information will be useful for maintenance service providers, infrastructure managers, asset owners and other stakeholders for improvement and maintenance effectiveness.
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| 45. |
- Thaduri, Adithya, et al.
(författare)
-
Reliability prediction of semiconductor devices using modified physics of failure approach
- 2013
-
Ingår i: International Journal of Systems Assurance Engineering and Management. - : Springer Science and Business Media LLC. - 0975-6809 .- 0976-4348. ; 4:1, s. 33-47
-
Tidskriftsartikel (refereegranskat)abstract
- Traditional approaches like MIL-HDBK, Telcordia, and PRISM etc. have limitation in accurately predicting the reliability due to advancement in technology, process, materials etc. As predicting the reliability is the major concern in the field of electronics, physics of failure approach gained considerable importance as it involves investigating the root-cause which further helps in reliability growth by redesigning the structure, changing the parameters at manufacturer level and modifying the items at circuit level. On the other hand, probability and statistics methods provide quantitative data with reliability indices from testing by experimentation and by simulations. In this paper, qualitative data from PoF approach and quantitative data from the statistical analysis is combined to form a modified physics of failure approach. This methodology overcomes some of the challenges faced by PoF approach as it involves detailed analysis of stress factors, data modeling and prediction. A decision support system is added to this approach to choose the best option from different failure data models, failure mechanisms, failure criteria and other factors.
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| 46. |
- Thaduri, Adithya, et al.
(författare)
-
Stress factor and failure analysis of constant fraction discriminator using design of experiments
- 2013
-
Ingår i: International Journal of Reliability, Quality and Safety Engineering (IJRQSE). - 0218-5393. ; 20:3
-
Tidskriftsartikel (refereegranskat)abstract
- Reliability prediction using traditional approaches were implemented at earlier stages of electronics. But due to advancements in science and technology, the above models are outdated. The alternative approach, physics of failure provides exhaustive information on basic failure phenomenon with failure mechanisms, failure modes and failure analysis becomes prominent because this method depends on factors like materials, processes, technology, etc., of the component. Constant fraction discriminators which is important component in NFMS needs to study failure characteristics and this paper provides this information on failure characteristics using physics of failure approach. Apart from that, the combined physics of failure approach with the statistical methods such as design of experiments, accelerated testing and failure distribution models to quantify time to failure of this electronic component by radiation and temperature as stress parameters. The SEM analysis of the component is carried out by decapsulating the samples and studied the impact of stress parameters on the device layout.
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| 47. |
- Thaduri, Adithya, et al.
(författare)
-
Study of reliability aspects in constant fraction discriminator
- 2011
-
Ingår i: 5th International Conference on Quality, Reliability and Information Technology (ICQRIT). - Kathmandu. ; , s. 1-7
-
Konferensbidrag (refereegranskat)abstract
- Reliability prediction using conventional constant failure models by standard books in early phases of electronics dominates wide acceptance. But after 1980s, there was wide variation in electronic technology which made above models obsolete. Physics of Failure approach provides information on basic failure phenomenon with failure mechanisms and failure modes becomes prominent as it entirely depends on materials, processes, technology etc. Constant fraction discriminators which are failing frequently in the field need to be studied and this paper provides information on failure characteristics using physics of failure approach. Apart from that, we combined statistical methods such as Design of Experiments, Accelerated testing and failure distribution models to quantify time to failure of this electronic component by radiation and temperature as stress parameters.
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| 48. |
- Wijaya, Andi, et al.
(författare)
-
Implementing lean principle into mining industry issues and challenges
- 2009
-
Konferensbidrag (refereegranskat)abstract
- 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.
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| 49. |
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| 50. |
- Ahmadi, Alireza, et al.
(författare)
-
An overview of trends in aircraft maintenance program development : past, present, and future
- 2007
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Ingår i: Risk, Reliability and Societal Safety. - London : Taylor and Francis Group. - 9780415447867 ; , s. 2067-2076
-
Konferensbidrag (refereegranskat)abstract
- The purpose of this paper is to describe the trends in aircraft maintenance program development during the last 50 years, including the reasons for the aircraft industry to change its view of maintenance. The major milestones and fundamental reasons for such development are also discussed and illustrated in relation to a flow diagram, which shows the logical and chronological order of the trends. Finally, the paper describes some possibilities and challenges as regards applying Information & Communication Technology (ICT) within the emerging approach of e-Maintenance in order to enhance the surveillance of aircraft maintenance program performance.
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