| 161. |
- Chattopadhyay, G., et al.
(författare)
-
Decision on economical rail grinding interval for controlling rolling contact fatigue
- 2005
-
Ingår i: International Transactions in Operational Research. - : Wiley. - 0969-6016 .- 1475-3995. ; 12:6, s. 545-558
-
Tidskriftsartikel (refereegranskat)abstract
- Rail players around the world have been increasing axle loads to improve the productivity of freight and heavy haul operations. This has increased the risk of surface cracks at curves because of rolling contact fatigue. Rail grinding has been considered an effective process for controlling these cracks and reducing risks of rail breaks. The complexity of deciding the optimal rail grinding intervals for improving the reliability and safety of rails is because of insufficient understanding of the various factors involved in the crack initiation and propagation process. This paper focuses on identifying the factors influencing rail degradation, developing models for rail failures and analyzing the costs of various grinding intervals for economic decision making. Various costs involved in rail maintenance, such as rail grinding, downtime, inspection, rail failures and derailment, and replacement of worn-out rails, are incorporated into the total cost model developed in this paper. Field data from the rail industry have been used for illustration.
|
|
| 162. |
- Chattopadhyay, G., et al.
(författare)
-
Estimation of parameter for rail degradation
- 2006
-
Ingår i: Condition Monitoring and Diagnostic Engineering Management. - Luleå : Luleå tekniska universitet. - 9789163188060 ; , s. 605-612
-
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.
|
|
| 163. |
- Chattopadhyay, G., et al.
(författare)
-
Modelling and analysis of rail maintenance cost
- 2007
-
Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 105:2, s. 475-482
-
Tidskriftsartikel (refereegranskat)abstract
- Lubrication at wheel flange and rails on sharp curves is considered as an effective solution for reducing wear loss of material from effective cross-section of rail and wheels. Rail administrations around the world have been increasing axle loads and traffic densities in rail networks. This has led to traffic initiated wear, fatigue initiated surface cracks and rail breaks. Limited research has been carried out on the overall impact of combining lubrication strategies and rail grinding. This paper presents a model for lubrication strategy and rail-grinding interval to reduce wear and rolling contact fatigue (RCF). Data from rail industry is collected and used for numerical illustration.
|
|
| 164. |
- Chattopadhyay, G., et al.
(författare)
-
Rail-wheel lubrication : A conceptual decision model
- 2005
-
Ingår i: International Conference on Operations Research Applications in Infrastructure Development in conjunction with the 2005 Annual Convention of Operational Research Society of India (ICORAID-2005-ORSI).
-
Konferensbidrag (refereegranskat)
|
|
| 165. |
|
|
| 166. |
- Chattopadhyay, G., et al.
(författare)
-
Work integrated blended learning for improvement by asset managers
- 2010
-
Ingår i: 23rd International Congress on Condition Monitoring and Diagnostic Engineering Management. - Hikone : Sunrise Publishing. - 9784883254194 ; , s. 95-101
-
Konferensbidrag (refereegranskat)abstract
- 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
|
|
| 167. |
- Chattopadhyay, S., et al.
(författare)
-
Influence of family history on risk of second primary cancers and survival in patients with squamous cell skin cancer
- 2020
-
Ingår i: British Journal of Dermatology. - : Oxford University Press (OUP). - 0007-0963 .- 1365-2133. ; 183:3, s. 488-494
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Patients with squamous cell skin cancer (SCC) have an excellent prognosis but second primary cancers (SPCs) weaken survival prospects. Family history is a known risk factor for cancer but whether it is a risk factor for SPC in patients with SCC is not known. Objectives: To quantify the risk of family history on SPCs in patients with SCC and estimate survival probabilities of patients with SPCs depending on family history. Methods: With 13 945 histologically verified SCCs, relative risks (RRs) were estimated for family history using a generalized regression model. For survival analysis, hazard ratios (HRs) were assessed using a multivariable Cox proportional-hazards model. Results: Family history of invasive SCC increased risk of second invasive SCC [RR = 42·92, 95% confidence interval (CI) 33·69–50·32] compared with risk without family history (RR 19·12, 95% CI 17·88–21·08). Family history of any nonskin cancer in invasive SCC increased risk of the same cancers to be diagnosed as SPC (RRFH = 1·48, 95% CI 1·35–1·61 vs. RRno FH = 1·40, 95% CI 1·32–1·48); significant increases were observed for seven different nonskin cancers. Most results were replicated for in situ SCC. SPC was deleterious for survival irrespective of family history; HR for patients with SPC was 4·28 (95% CI 3·83–4·72) vs. those without SPC (1·04). Conclusions: Family history of nonskin cancer was associated with approximately a doubling of risk for SPCs in patients with SCC. SPC increases the death rate in patients with SCC 3–4 times, irrespective of family history. Taking family history into account at SCC diagnosis may help prevention or early detection of SPCs. What's already known about this topic? Second primary cancers (SPCs) are frequently diagnosed in patients with invasive and in situ squamous cell carcinoma (SCC); some epidemiological studies suggest a link to immune dysfunction. Family history of cancer is a risk factor for practically all first primary cancers but whether it also influences risk of SPCs in patients with SCC is not known. The possible influence of family history on survival in patients with SCC remains to be established.
|
|
| 168. |
|
|
| 169. |
|
|
| 170. |
- Kumar, Saurabh, et al.
(författare)
-
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
-
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.
|
|
