Academic literature on the topic 'Cycles - Repair And Maintenance Of Specific Models'
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Journal articles on the topic "Cycles - Repair And Maintenance Of Specific Models"
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Romanov, Vladimir S., and Valery G. Goldshtein. "To the question of damage, maintenance and repairs of submersible electric equipment for oil production." Vestnik of Samara State Technical University. Technical Sciences Series 28, no. 2 (July 27, 2020): 111–23. http://dx.doi.org/10.14498/tech.2020.2.8.
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In optimizing and managing the life cycles of submersible electrical equipment (SEE) for oil production, an integrated approach to the organization of maintenance and repairs (MRO) is advisable based on the development of a more advanced strategy for carrying out repair cycles. It is stated that the maintenance and repair strategies adopted by the oil industry do not fully ensure operational efficiency, which leads to an increase in premature equipment failures, a reduction in turnaround times and, as a result, losses for oil companies. The advantages and disadvantages of approaches to organizing the operation of SEE on the operating time and the actual state in the planning, implementation of maintenance and repair, as well as the feasibility of their complex application are evaluated. It is proposed to use statistical models to make an informed decision on determining the composition and period of MRO, forecasting the boundary states of sets in general and specific SEE electrical installations. At a given operating time, it is possible to determine the basic laws of the appearance of defects and the mean time between failures (MTBF) of the elements, as well as the fleet of equipment of oil-producing enterprises as a whole. The results obtained are the rationale for a set of recommendations to improve operational efficiency and optimize life cycle management of submersible electrical equipment for oil production.
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Islam, Md Shafiqul, Shayla Sharmin, and Jebunnesa Islam. "Multiple repair scenario of life cycle cost of RCC girder bridge using Markov chain model." Challenge Journal of Concrete Research Letters 10, no. 4 (December 21, 2019): 75. http://dx.doi.org/10.20528/cjcrl.2019.04.001.
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At present, many road authorities in the world face challenges in condition monitoring diagnosis of distress and forecasting deterioration, strengthening and convalescence of aging bridge structures. The accurate prediction of the future condition is crucial for optimizing the maintenance activities. It is very tough to predict the actual performance scenario or actual in–situ structures without carrying out inspection. Limited availability of detailed inspection data is considered as one of the major drawbacks in developing deterioration models. In State Based Markov deterioration (SNMD) modelling, the main job is to estimate transition probability matrixes (TPMs). In this paper, Markov Chain Monte Carlo (MCMC) is used to estimate TPMs. In Markov Chain Model, future conditions depend on only present bridge inspection data. Multiple repair options are adopted in order to optimize life cycle cost. Repairs are needed when the critical chloride concentration exceeds 0.2. Three distinct types of cost corresponding to each repair option is considered. The objective of this paper is to minimize the life cycle cost considering appropriate repair timings of mixed repair methods. Variation of life cycle cost of five different concretes (stronger to weaker) using three different repair option is shown in this paper. For specific normalized condition of concrete’s failure probability (0.3) and specific type of concrete, variation of life cycle cost using multiple repair options is also shown in this paper.
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Cardeal, Gonçalo, Kristina Höse, Inês Ribeiro, and Uwe Götze. "Sustainable Business Models–Canvas for Sustainability, Evaluation Method, and Their Application to Additive Manufacturing in Aircraft Maintenance." Sustainability 12, no. 21 (November 3, 2020): 9130. http://dx.doi.org/10.3390/su12219130.
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The topic of sustainable business models is growing in literature and in the industry, driving companies to search for opportunities to improve their impact on the three pillars of sustainability—profit, people, and planet (economic, social, and environmental). However, the process of developing sustainable business models is often complex, due to conflicting objectives from the three dimensions of sustainability. This paper presents a procedure model that supports the design and assessment of business models with a sustainable perspective, by integrating a new business model canvas for sustainability (BMCS) and an evaluation method to assess it. A comprehensive assessment is proposed, performed in a life cycle perspective. The proposed model is applied and validated with a real case study, based on a new business model for an aircraft maintenance, repair, and overhaul company. The case is based on shifting from traditional maintenance, repair, and overhaul activities to adopting additive manufacturing as an activity that allows manufacturing optimized spare parts with benefits for the costumer. The results show the application of the procedure model on a specific case study, as well as the potential of additive manufacturing as a driver for more sustainable business models in the aircraft maintenance sector.
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Tomasova, Kristyna, Michal Kroupa, Asta Forsti, Pavel Vodicka, and Ludmila Vodickova. "Telomere maintenance in interplay with DNA repair in pathogenesis and treatment of colorectal cancer." Mutagenesis 35, no. 3 (February 21, 2020): 261–71. http://dx.doi.org/10.1093/mutage/geaa005.
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Abstract Colorectal cancer (CRC) continues to be one of the leading malignancies and causes of tumour-related deaths worldwide. Both impaired DNA repair mechanisms and disrupted telomere length homeostasis represent key culprits in CRC initiation, progression and prognosis. Mechanistically, altered DNA repair results in the accumulation of mutations in the genome and, ultimately, in genomic instability. DNA repair also determines the response to chemotherapeutics in CRC treatment, suggesting its utilisation in the prediction of therapy response and individual approach to patients. Telomere attrition resulting in replicative senescence, simultaneously by-passing cell cycle checkpoints, is a hallmark of malignant transformation of the cell. Telomerase is almost ubiquitous in advanced solid cancers, including CRC, and its expression is fundamental to cell immortalisation. Therefore, there is a persistent effort to develop therapeutics, which are telomerase-specific and gentle to non-malignant tissues. However, in practice, we are still at the level of clinical trials. The current state of knowledge and the route, which the research takes, gives us a positive perspective that the problem of molecular models of telomerase activation and telomere length stabilisation will finally be solved. We summarise the current literature herein, by pointing out the crosstalk between proteins involved in DNA repair and telomere length homeostasis in relation to CRC.
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Apryshkin, A. S., and G. S. Khazanovich. "Determination of capacity and comfort indicators of a passenger elevator." SAFETY OF TECHNOGENIC AND NATURAL SYSTEMS, no. 1 (2021): 38–50. http://dx.doi.org/10.23947/2541-9129-2021-1-38-50.
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Introduction. Elevators are mass weight-handling units used by millions of residents of multi-storey buildings. Safety of elevator units and comfort of their use are determined not only by the correct choice of their design and parameters, but first of all, by the organization of the maintenance system. Each elevator is an individual unit that serves a residential building with a specific number of passengers, number of floors and other features. However, regulatory documents recommend standard maintenance plans. There is the need to establish the relationship between the loading modes of the main components and the optimal scheme of technical and repair works. The present work is devoted to the solution of this problem, along with the study of transport comfort. Problem Statement. The operation of the elevator in a residential building with a number of floors N occurs in separate cycles. Standing, lift call, and destination floors are random variables for which probabilistic characteristics must be reliably established. In general, the elevator operation mode includes three stages: calling to the passenger boarding level, moving with passengers to the destination level, and waiting for the next cycle. There are stops inside the movement stages. The specific problem of mathematical description of the random process of implementing the operating characteristics of the main drive of the elevator is reduced to two directions: 1) the development of mathematical models for the formation of the main indicators of the main elevator drive load during the cycle (net machine time τmi and the number of switches n)i; 2) the study of the relationship between passenger traffic, building residential density and cycle duration. Theoretical Part. To meet these objectives the authors have performed the studies of the following main processes characterizing the functioning of the lift, the level of capacity of the transport drive and comfort: the development of mathematical models of formation of indicators of the elevator drive load; the establishment of the relationship of traffic flow, residential density and the duration of the cycle; development of methodology for calculation of the number of flights went by the elevator in different modes; development of methods of calculating the transport comfort indicator; justification of the structure of the algorithm for modeling the operating modes of the elevator. Conclusion. The paper provides the results, which complement the theoretical provisions for determining the capacity and transport comfort of elevators.
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Strømland, Øyvind, Marc Niere, Andrey A. Nikiforov, Magali R. VanLinden, Ines Heiland, and Mathias Ziegler. "Keeping the balance in NAD metabolism." Biochemical Society Transactions 47, no. 1 (January 9, 2019): 119–30. http://dx.doi.org/10.1042/bst20180417.
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Abstract Research over the last few decades has extended our understanding of nicotinamide adenine dinucleotide (NAD) from a vital redox carrier to an important signalling molecule that is involved in the regulation of a multitude of fundamental cellular processes. This includes DNA repair, cell cycle regulation, gene expression and calcium signalling, in which NAD is a substrate for several families of regulatory proteins, such as sirtuins and ADP-ribosyltransferases. At the molecular level, NAD-dependent signalling events differ from hydride transfer by cleavage of the dinucleotide into an ADP-ribosyl moiety and nicotinamide. Therefore, non-redox functions of NAD require continuous biosynthesis of the dinucleotide. Maintenance of cellular NAD levels is mainly achieved by nicotinamide salvage, yet a variety of other precursors can be used to sustain cellular NAD levels via different biosynthetic routes. Biosynthesis and consumption of NAD are compartmentalised at the subcellular level, and currently little is known about the generation and role of some of these subcellular NAD pools. Impaired biosynthesis or increased NAD consumption is deleterious and associated with ageing and several pathologies. Insults to neurons lead to depletion of axonal NAD and rapid degeneration, partial rescue can be achieved pharmacologically by administration of specific NAD precursors. Restoring NAD levels by stimulating biosynthesis or through supplementation with precursors also produces beneficial therapeutic effects in several disease models. In this review, we will briefly discuss the most recent achievements and the challenges ahead in this diverse research field.
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Chlon, Timothy M., Elizabeth E. Hoskins, Sonya Ruiz-Torres, Christopher N. Mayhew, Kathryn A. Wikenheiser-Brokamp, Stella M. Davies, Parinda A. Mehta, Kasiani C. Myers, James M. Wells, and Susanne I. Wells. "Inducible Loss of the Fanconi Anemia Pathway in iPSC Causes Rapid Cell Cycle Arrest and Apoptosis through ATM/ATR and p53 Signaling." Blood 124, no. 21 (December 6, 2014): 3528. http://dx.doi.org/10.1182/blood.v124.21.3528.3528.
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Abstract As the source of all cells in the developing embryo proper, embryonic stem cells (ESC) bear the unique responsibility to prevent mutations from being propagated throughout the entire organism and the germ line. It is likely for this reason that ESC and induced pluripotent stem cells (iPSC) maintain a dramatically lower mutation frequency than cultured somatic cells. Multiple mechanisms for this enhanced genomic surveillance have been proposed, including hypersensitivity of DNA damage response signaling pathways and increased activity of error-free DNA repair pathways, such as homologous recombination. However, the effect of loss of function of DNA repair pathways in these cells remains poorly understood. The Fanconi Anemia (FA) pathway is a DNA repair pathway that is required for the repair of DNA interstrand crosslink damage and also promotes repair of DNA double-strand breaks by homologous recombination . Genetic defects in this pathway cause a disease characterized by bone marrow failure and extreme cancer incidence. Several recent studies have revealed that the FA pathway is required for efficient somatic cell reprogramming to iPSC and suggest that FA cells undergo cell death during this process. Another recent study found that the growth of FA patient-specific iPSC was attenuated with a G2/M arrest when compared to control iPSC, suggesting that these cells arrest upon failed DNA repair. In this study, we sought to determine the effects of acute loss of function of the FA pathway in iPSC through the generation of FA patient-derived iPSC with inducible complementation of the defective FA gene. Fibroblasts were cultured from skin biopsies of multiple FA patients and transduced with a lentiviral vector expressing the complementing FA gene product under DOX-inducible control. Cells were then reprogrammed to iPSC using episomal transfection. These cells formed iPSC colonies only when reprogramming was carried out in the presence of DOX, confirming that the FA pathway is required for efficient reprogramming. Once cell lines were obtained, DOX-dependent FA functionality was verified based on FANCD2 monoubiquitination and nuclear focus formation after treatment with DNA damaging agents. We then cultured the iPSC for extended periods of time in the presence and absence of DOX. Interestingly, the cultures underwent profound cell death and cell cycle arrest within 7 days of DOX-withdrawal and completely failed to expand after one passage. EdU cell cycle analysis confirmed cell cycle arrest in the G2/M phase. Furthermore, cleaved caspase 3 staining confirmed that the number of apoptotic cells increased by 3-fold in the -DOX culture. Despite these effects, cells cultured in both the presence and absence of DOX formed teratomas in nude mice, thus indicating the maintenance of full differentiation capacity in the absence of the FA pathway. In order to determine the mechanisms underlying G2/M arrest and cell death, expression of p53 and its target genes was detected by both western blot analysis and qRT-PCR. Only a slight increase in p53 activation was observed by 7 days post DOX-withdrawal. Furthermore, knockdown of p53 resulted in rescue from apoptosis to normal levels but not rescue from cell cycle arrest. Increased ATM and ATR DNA damage sensor kinase activities were also detected in –DOX cells, concominant with increased phosphorylation of the ATM-target Chk2 and reduced abundance of the G2/M checkpoint protein CDC25A. These results reveal hyperactive DNA damage responses upon FA loss which may underlie the attenuated cell cycle progression of FA-iPSC independent of p53. Remarkably, effects in this FA model system appear equivalent to those responsible for the depletion of HSC in the bone marrow of FA patients. Thus, iPSC models may be useful for future studies of the mechanisms underlying FA stem cell arrest and for the development of therapeutics that alleviate these phenotypes. Disclosures No relevant conflicts of interest to declare.
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Shi, Wei, Therese Vu, Glen Boyle, Fares Al-Ejeh, Tej Pandita, Krzysztof Ginalski, Maga Rowicka, Steven W. Lane, and Kum Kum Khanna. "SSB1/NABP2 and SSB2/NABP1 Have Essential and Overlapping Roles in Maintaining Hematopoietic Stem and Progenitor Cells." Blood 126, no. 23 (December 3, 2015): 2405. http://dx.doi.org/10.1182/blood.v126.23.2405.2405.
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Abstract Single-stranded DNA binding (SSB) proteins are essential for a variety of DNA metabolic processes and the maintenance of genomic stability. SSB1 and its homolog SSB2, share greater sequence and domain homology to the archaeal and bacterial SSBs than eukaryotic RPA. They form complexes with two other proteins, C9Orf80 and INTS3, and play roles in mediating transcription and DNA repair. SSB1 (also known as OBFC2B or NABP2) is recurrently mutated in various cancers, however the precise function in normal development is incompletely understood. We have previously shown that Ssb1 is required for skeletogenesis, telomeric homeostasis and genomic stability in vivo while Ssb2 knockout mice are viable and grow normally without any detectable phenotype. Interestingly, we observed pronounced upregulation of Ssb2 in response to Ssb1 deletion and modest up-regulation of Ssb1 in response to Ssb2 deletion, suggesting that Ssb1 and Ssb2 may have some overlapping functions. To investigate the specific roles of both Ssb1 and Ssb2 in adult tissue homeostasis, we generated conditional double-knockout (DKO) mouse models of both genes. DKO in adult mice was achieved by using a tamoxifen-inducible Cre (Ssb1fl/fl Ssb2fl/fl R26-CreERT2), in which Ssb1 and Ssb2 are conditionally deleted by the administration of tamoxifen. Induced DKO mice become moribund within seven days featured with pancytopenia and dramatic loss of hematopoietic stem and progenitor cells (HSPCs), suggesting that Ssb1 and Ssb2 are required for the maintenance of haematopoietic stem and progenitors cells (HSPCs). DKO bone marrow was markedly hypocellular with reduction in all lineages of haematopoietic development. Functionally, HSPCs in DKO mice show decreased quiescence at the early stage followed by decreased proliferation and increased cell loss due to apoptotic cell death at the later stage, suggesting the imbalanced bone marrow homeostasis upon DKO may eventually result in exhaustion of the stem cell pool in DKO mice. Furthermore, bona fide HSPC intrinsic functional deficiency caused by DKO was confirmed by competitive bone marrow transplant, where DKO bone marrows showed abolished differentiation capacity and failed to repopulate the bone marrows of recipient mice after induction of DKO in the established engraftments from the Ssb1fl/fl Ssb2fl/fl R26-CreERT2 donors. Gene expression of DKO HSPCs demonstrated an exacerbated p53/p21 DNA damage response and pronounced interferon response. Validating these findings, stabilization of p53 and increased apoptotic cell death were observed in DKO bone marrows and HSPCs and induction of cell cycle and expression of interferon target genes was confirmed by QPCR. DKO HSPCs have increased expression of IFN induced surface markers such as Sca1. The IFN response was intrinsic to HSPCs. Mechanistically, DKO HSPCs manifest a profile of stalled replication forks on DNA combing analysis, unrepaired double strand breaks (increased gammaH2Ax foci and alkaline comet tail moment) and telomeric loss resulting in widespread chromosomal instability. DKO HSPC showed aberrant cytoplasmic accumulation of single stranded DNAs, with R-loop formation (DNA:RNA hybrid), driving this genetic instability and cell-intrinsic interferon response. Altogether, these data provide strong evidence that Ssb1 and Ssb2 have essential functions in regulating haematopoiesis through repairing replication associated DNA damage as well as resolution of R-loop generated during transcription, to maintain genomic stability during normal HSPC homeostasis. Disclosures No relevant conflicts of interest to declare.
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Dash, Sanjit Kumar, Satyam Raj, Rahul Agarwal, and Jibitesh Mishra. "Automobile Predictive Maintenance Using Deep Learning." International Journal of Artificial Intelligence and Machine Learning 11, no. 2 (July 2021): 1–12. http://dx.doi.org/10.4018/ijaiml.20210701.oa7.
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There are three types of maintenance management policy Run-tofailure (R2F), Preventive Maintenance (PvM) and Predictive Maintenance (PdM). In both R2F and PdM we have the data related to the maintenance cycle. In case of Preventive Maintenance (PvM) complete information about maintenance cycle is not available. Among these three maintenance policies, predictive Maintenance (PdM) is becoming a very important strategy as it can help us to minimize the repair time and the associated cost with it. In this paper we have proposed PdM, which allows the dynamic decision rules for the maintenance management. PdM is achieved by training the machine learning model with the datasets. It also helps in planning of maintenance schedules. We specially focused on two models that are Binary Classification and Recurrent Neural Network. In Binary Classification we classify whether our data belongs to the failure class or the non failure class. In Binary Classification the number of cycles is entered and classification model predicts whether it belongs to the failure/non failure class.
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Sime, Muluneh, Gary Bailey, Elie Y. Hajj, and Rami Chkaiban. "Road Load Based Model for Vehicle Repair and Maintenance Cost Estimation." Transportation Research Record: Journal of the Transportation Research Board 2674, no. 11 (September 10, 2020): 490–97. http://dx.doi.org/10.1177/0361198120945977.
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A techno-economic model is developed based on road-load simulation results expressed in relation to slip energy (SE) at the tire–pavement interface and the repair and maintenance (R&M) cost obtained from published sources and data from state agencies. Tire SE allows for the consideration of aggressive acceleration and deceleration, high torque conditions (for instance, driving an upslope grade), and roadway curvature. Tire SE data used in this effort were generated using physics-based simulation models of different vehicle types for arrays of road conditions (e.g., grades, curvatures) and driving cycles (i.e., vehicle speed profiles). R&M costs were estimated for various vehicle categories and accumulated vehicle mileage. The approach is based on relating the probability density functions (PDFs) of SE and R&M costs. Asymptotic series expansion for an incomplete gamma function was used to approximate the gamma functions and to determine the gamma ratio function that is used as the coefficient to SE to estimate R&M costs. The average R&M cost per mile results from the model compared with the arithmetic mean R&M cost data from fleet operators and published data. The model can serve as a method for predicting R&M cost as a function of road load to vehicle fleet.
Books on the topic "Cycles - Repair And Maintenance Of Specific Models"
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Storer, Jay. Chilton's toyota camry 2002-06 repair manual: Covers U.S. and Canadian models of Toyota Camry, Avalon, Solara, and Lexus ES 300/330 models : does not include information specific to the 2005 and 2006 3.5L V6 engine. Newbury Park, CA: Haynes North America, Inc., 2009.
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Layne, Ken. Ford Taurus & Mercury Sable automotive repair manual: Models covered, Ford Taurus and Mercury Sable 1996 through 2005 : does not include information specific to SHO or variable fuel models. Sparkford Nr Yeovil, Somerset, England: Haynes Pub. Group, 2005.
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Harold, Haynes John, ed. Chrysler Sebring, Dodge Stratus & Avenger automotive repair manual: Models covered, Chrysler Sebring convertible, coupe, and sedan (1995 through 2005), Dodge Stratus coupe and sedan (2001 through 2005), Dodge Avenger (1995 through 2000) ; does not include information specific to flexible fuel vehicles. Sparkford, Nr Yeovil, Somerset, England: Haynes Pub. Group, 2006.
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Bogart, Jay, and Jon Engelman. Suzuki DR-Z400E, S & SM 2000-2006 (Clymer Motorcycle Repair). Clymer Publishing, 2006.
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Publications, Clymer, ed. Clymer Suzuki DR-Z400E, S & SM, 2000-2006. Overland Park, Kan: Clymer, 2006.
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Ford Focus 2012 Thru 2014: Does Not Include Information Specific to Focus Electric Models. Haynes Publishing Group P.L.C., 2015.
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Manuals, Editors of Haynes. Jeep Grand Cherokee from 2005-2018 Haynes Repair Manual : (Does Not Include Information Specific to Diesel Engine Models or 6. 2L Supercharged Models). Haynes Manuals, Incorporated, 2020.
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Editors, The Nichols/Chilton. GM Firebird 1982-94: All U.S. and Canadian models (Chilton Model Specific Automotive Repair Manuals). Haynes Manuals, Inc., 1998.
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Manuals, Editors of Haynes. Jeep Liberty & Dodge Nitro 2002-2012 Haynes Repair Manual : (Does Not Include Information Specific to Diesel Models). Haynes Manuals, Incorporated, 2020.
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Mazda MX-5 Miata 1990 Thru 2014 Haynes Repair Manual: Does Not Include Information Specific to Turbocharged Models. Haynes Publishing Group P.L.C., 2015.
Find full textBook chapters on the topic "Cycles - Repair And Maintenance Of Specific Models"
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Olkhovik, Evgeniy, Pavel Garibin, and Vladimir Tsuprik. "Seaport Facilities in Maritime Transport Infrastructure in the Arctic." In Handbook of Research on International Collaboration, Economic Development, and Sustainability in the Arctic, 338–69. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-6954-1.ch016.
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Harbor facilities are important elements of international transport infrastructure. Maintenance of the existing mooring facilities along with the construction of new ports and harborage areas have revealed a number of challenges at all stages of the life cycle. In the Arctic, adverse climate conditions impose specific constraints on the processes of study, engineering, construction, and exploitation of seaport facilities. In this chapter, the authors provide the examples of design solutions as well as specific features of construction and maintenance of seaport facilities in various conditions, suggest technical and hardware solutions for monitoring and safeguard of cargo harbor facilities in the Arctic, measures to reconstruction, repair, utilization, conservation, and elaboration of computational information models. The chapter considers major objectives of environmental safety control during the performance of cargo handling operations, oil spills prevention and response, training and education of hydraulic engineers to perform activities in the Arctic.
Conference papers on the topic "Cycles - Repair And Maintenance Of Specific Models"
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Muldoon, Kellen. "Cyclic Operation of Supercritical High Pressure Feedwater Heater Study." In ASME 2013 Power Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/power2013-98317.
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As more renewable energy sources come on line with the inherent inconsistency of load dispatch feedwater heaters become subject to more frequent and rapid cyclic operation. In a recent project, American Exchanger Services (AM-EX) was asked to gather and analyze operating information on a high pressure feedwater heater during daily rapid load changes. This particular supercritical coal plant was designed to operate in flexible load environments, thus acquiring data during the summer months was optimal. The heater was run from rest to full power while temperature data was acquired. All data from the study and supporting plant information was used to generate models for preparing maintenance projections, informing future designs, and repair recommendations. The primary component of focus is the desuperheating zone exhaust where tube failure tends to be greatest caused by wet wall conditions. The result of the analysis was less conclusive than was anticipated. Actual performance of the heaters is a key issue and there were specific indications that the heaters were not performing to specifications. A more detailed thermal performance analysis using the ASME PTC12.1 should be considered to accurately determine the extent to which the heaters are meeting design performance.
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Waghmode, Laxman Yadu, and Anil Dattatraya Sahasrabudhe. "On the Expected Number of Failures and Maintenance Cost Prediction of Repairable Systems From Life Cycle Cost Modeling Perspective." In ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/detc2010-28044.
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The objective of this paper is to provide some useful insights on how cost driving events are related to the characteristics of failure distributions and the product lifetime (design life) in case of repairable systems. Repairable systems are those that can be restored to their fully operational capabilities by any method, other than the replacement of the entire system. In case of repairable systems, the components can be repaired or adjusted rather than replaced, whenever a breakdown occurs and thus such systems experience multiple failures over their life span. For majority of repairable systems, the life time maintenance and repair costs dominate the life cycle cost. To predict the maintenance and repair cost, failure data, maintenance data and repair time data is needed which is not readily available at the system design stage. When a repairable system is put into service, how many times it will fail over its life span depends on its reliability. Similarly, how fast the system is restored to its working condition when it fails (maintainability), also affect the costs incurred. Thus, the expected number of failures, time lost in restoring the system after each failure and cost per failure are important from life time maintenance cost prediction viewpoint. The expected number of failures depends upon the time to failure distribution of the system components and the after repair state of the system. In this paper, a modeling methodology is suggested for prediction of life time maintenance and repair cost of repairable systems based on expected number of failures. The repairable system lifetime is modeled using a two parameter Weibull distribution. The expected number of failures are estimated for renewal process (as-good-as-new after repair state) and minimal repair process (as-bad-as-old after repair state). The expected maintenance and repair costs are also evaluated for six different failure distributions. The technique has been illustrated through a specific application, namely an industrial pump and the results are presented.
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Semiga, Vlado, Aaron Dinovitzer, Sanjay Tiku, and Geoff Vignal. "Liquid Pipeline Location Specific Cyclic Pressure Determination." In 2018 12th International Pipeline Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/ipc2018-78717.
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In the majority of liquid pipelines, the pump station discharge pressure ranges are much greater than the pressure ranges experienced at the suction end of the downstream pump station. Consequently, the cyclic pressure induced fatigue damage accumulation rate is greater at the discharge end than at the suction end of a given pipeline segment. In completing an integrity assessment of a fatigue susceptible feature, assuming that the pump station discharge cyclic pressure profile applies to all features in the line segment is conservative. This conservative assumption can lead to un-necessary repairs, unintentional damage from over-prescribed maintenance, or inefficient decisions regarding maintenance action prioritization. The following paper presents the results of a Canadian Energy Pipeline Association (CEPA) initiative to develop a simple approach to define the cyclic pressure history at any point in a liquid pipeline segment based on the bounding discharge and suction pump station Supervisory Control and Data Acquisition (SCADA) pressure time history data. The approach was developed based on collected operating pipeline SCADA pressure time history data for line segments with intermediate measurement points which could be used to validate the developed model. The pressure time histories for all the locations were analyzed using a Rainflow cycle counting technique to develop pressure range spectra (i.e. histograms of pressure range events) and the cyclic pressure severity of each of the time histories was characterized by the Spectrum Severity Indicator (SSI). The SSI represents the number of annual 90MPa hoop stress cycles required to accumulate the same fatigue damage as the actual pressure spectrums. The technique presented in this paper illustrates how to infer the pressure range spectra or SSI at intermediate locations. The technique is shown to be a significant improvement (i.e. higher location specific accuracy) than either applying the discharge pressure spectrum or applying a linear interpolation between discharge and suction conditions in fatigue life assessments. The liquid pipeline cyclic pressure characterization technique presented in this paper will permit integrity assessment or severity ranking of features along a pipeline to be based on an accurate local pressure profile rather than an upper bound. This understanding will help to improve the accuracy of defect loading, one of the three main pillars in integrity assessment (i.e., loading, geometry, materials) for defects susceptible to cyclic loading (e.g., cracking, mechanical damage).
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Mu¨ller, Matthias, Stephan Staudacher, Winfried-Hagen Friedl, Rene´ Ko¨hler, and Matthias Weißschuh. "Probabilistic Engine Maintenance Modeling for Varying Environmental and Operating Conditions." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22548.
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The maintenance and reliability of aircraft engines is strongly influenced by the environmental and operating conditions they are subjected to in service. A probabilistic tool has been developed to predict shop visit arisings and respective maintenance workscope that depends on these factors. The tool contains a performance model of the engine and a number of physics-based damage mechanisms (at piece part level). The performance model includes variation of performance relevant parameters due to production scatter and delivers the conditions to determine the deterioration of the individual parts. Shop visit maintenance is modeled as a result of limitations to engine operation, e.g. reaching TGT limit, or mechanical deterioration. The influence of maintenance actions on engine performance is determined on component basis. The maintenance strategy can consist of proactive and reactive maintenance elements. The decision of repair or replacement of any single part is implemented through a sum of different logic rules in the model. The loading capacity scatter depends on the engine type and is operator independent. It is represented via data-driven distribution functions, in which the probabilities of failure, repair and replacement for each part are specified depending on the number of reference flight cycles. The loading variation is considered through a physics-based cycle weighting. The developed tool runs a Monte Carlo simulation in which a fleet of engines is modeled through their respective lifetime of maintenance and performance deterioration. Using an example it is shown that the model can describe the effects of varying environmental and operating conditions on part damage, and therefore engine maintenance cost and reliability.
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Nelson, Jeremy, Trace Silfies, Brian Crandall, and Jorge Penso. "Review of Life Assessment and Repair Strategies for Hydrogen Reformer Furnace Outlet Header Castings." In ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21555.
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Abstract Steam methane reforming is the most common method of hydrogen production relevant for plants in the petroleum upgrading, downstream refining, methanol, and ammonia industries. Owner-operators of steam methane reformer furnaces continue to make repair and replacement decisions that involve the cast outlet manifold fittings. One key part of these plans is assessment of the weldability and remaining life of the cast components. The 20Cr-32Ni-1Nb alloy casting materials typically used in the outlet manifolds are usually operated in the low end of their creep temperature range but are subject to metallurgical aging mechanisms which reduce their ductility, weldability, homogeneity, and fracture toughness. This paper covers the practices employed by several owner-users to optimize the lifecycle costs of the outlet manifold castings. These practices include but are not limited to controlled materials specifications, in-situ weldability tests, non-destructive testing in-situ and destructive testing post service, and repair practices such as annealing heat treatments. This paper also includes a limited survey of several owner-users and their fleets of reformer heaters. The details in the survey include the population of affected cast manifold components, alloy grades for the castings and welds, operating temperature ranges, number of startup and shutdown cycles, ranges of time in service, generic design details, and repair case studies. Also discussed are recent improvements in the state of the art for high temperature materials property data-gathering, as well as the structural modeling via Finite Element Methods. These new technologies are opportunities for future work to develop better strategies in the areas of condition assessment, repair planning, and remaining life prediction, taking into account the relevant parameters of installed manifold components, including: specific aging behavior of the casting chemistry, component mechanical design details, as well as the welding and heat treatment parameters during initial fabrication and subsequent maintenance activities.
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Narayanaswamy, Ram. "The Process of Materials Selection for Pipeline Systems Optimization for Life Cycles." In ASME 2017 India Oil and Gas Pipeline Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/iogpc2017-2404.
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The selection of pipeline materials requires consideration of design, construction, operations, maintenance, threats, hazards, risks, safety and economics. Codes and standards provide mandatory and optional requirements and guidelines for the selection of materials. Experience and industry practice help to develop and implement requirements beyond mandatory and code minima, and to augment the achievement of safety and realization of the value of pipeline assets. Both codes and experience get updated over time. When selecting and using materials for pipeline systems, it becomes important to meet with code essentials, while simultaneously recognizing the recommendations of design engineers, materials specialists, manufacturers, installers and operators. There is a wide gamut of materials that can be considered for pipeline systems. These include metallic and non-metallic materials. While steels are still used as the workhorse material in the industry, several non-metallic materials are gaining prominence. These include thermoset materials, for example, reinforced plastics, and thermoplastic materials, such as high-density polyethylene. In addition to pipe, there have been significant developments in other pipeline component materials, such as for valves, fittings, flanges, gaskets, seals, adhesives, bolts and nuts. Considerable advancements have also taken place in the realm of joining and repair methods, for metallic and non-metallic materials. Many of these materials and methodologies are of a proprietary nature, with limits on how much information is divulged by the manufacturers and producers, and what is subject to information that is shared based on confidentialities. Proprietary materials, especially non-metallic products, and some corrosion resistant alloys, are generally not extensively addressed in codes and standards, especially in comparison with steel-based materials that are of the commodity type. Some internationally recognized specifications and standards address the requirements for the qualification of pipeline components, including pipe, fittings, flanges and valves, based on non-metallic materials. Other internationally recognized standards and specifications address the requirements for apparently commodity type materials and materials that are considered to be generally corrosion resistant and relatively long lasting, however, can be susceptible to failure when subjected to specific threats. This paper provides an overview of the process of selection of pipeline materials addressing the above considerations and gives an outline for the implementation of such a process. It describes ways in which a balanced approach to the use of codes and standards that are necessary for regulatory and mandatory compliance, and the application of the benefits of proprietary materials that are available for commercial purposes can be achieved. Thereby, the optimization of asset life cycle and augmentation of safety and reliability during pipeline operations can be enabled.
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Mo¨ller, Bjo¨rn Fredriksson, Mitsuru Obana, Mohsen Assadi, and Athanasios Mitakakis. "Optimisation of HAT-Cycles – With and Without CO2 Capture." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53734.
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In a world where distributed power generation and deregulation of energy markets are on everyone’s agenda, the need for highly efficient power plants with short lead times is greater than ever. Although at present combined cycles provide a solution, development of ever more advanced machines to increase efficiency and lower the environmental impact has led to high maintenance costs and a decrease in availability. The Humid Air Turbine (HAT) represents a different approach, suitable for distributed power generation in the medium power range. The HAT cycle, and other wet gas turbine cycles, which have been extensively studied during the last ten years, show as high an efficiency as that of combined cycles, but at a lower specific cost and, with inherently low emissions of NOx. Despite all research done no full-scale plant has been built as yet. CO2 capture is another concept widely studied in recent years. In the present study three HAT cycle configurations are investigated, two of them connected to a post-combustion CO2-capture plant. Thermodynamic and thermoeconomic optimisation of the plants was performed using genetic algorithms (GA), a robust optimisation technique based on Darwinian evolution theories. The three configurations studied were 1) a standard inter-cooled HAT cycle, referred to as the reference cycle, 2) the reference cycle together with an integrated CO2-capture plant taking the energy needed for the CO2 separation from the exhaust heat of the turbine, and 3) the reference cycle together with a CO2 capture plant, in which the energy is supplied by a separate bio-fuelled boiler. This third configuration enables all fossil-based CO2 to be separated. All power cycles were modelled using IPSEpro, a heat- and mass-balance software, employing advanced component models developed by the authors. It has an interface for optimisation and the possibility of employing user-defined objective functions. The impact of CO2 taxation was studied to determine showing which configuration is the most economical at the current fuel-price and tax-level.
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Mora, Rafael G., Curtis Parker, Patrick H. Vieth, and Burke Delanty. "Probability of Exceedance (POE) Methodology for Developing Integrity Programs Based on Pipeline Operator-Specific Technical and Economic Factors." In 2002 4th International Pipeline Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/ipc2002-27224.
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With the availability of in-line inspection data, pipeline operators have additional information to develop the technical and economic justification for integrity verification programs (i.e. Fitness-for-Purpose) across an entire pipeline system. The Probability of Exceedance (POE) methodology described herein provides a defensible decision making process for addressing immediate corrosion threats identified through metal loss in-line inspection (ILI) and the use of sub-critical in-line inspection data to develop a long term integrity management program. In addition, this paper describes the process used to develop a Corrosion In-line Inspection POE-based Assessment for one of the systems operated by TransGas Limited (Saskatchewan, Canada). In 2001, TransGas Limited and CC Technologies undertook an integrity verification program of the Loomis to Herbert gas pipeline system to develop an appropriate scope and schedule maintenance activities along this pipeline system. This methodology customizes Probability of Exceedance (POE) results with a deterministic corrosion growth model to determine pipeline specific excavation/repair and re-inspection interval alternatives. Consequently, feature repairs can be scheduled based on severity, operational and financial conditions while maintaining safety as first priority. The merging of deterministic and probabilistic models identified the Loomis to Herbert pipeline system’s worst predicted metal loss depth and the lowest safety factor per each repair/reinspection interval alternative, which when combined with the cost/benefit analysis provided a simplified and safe decision-making process.
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Giesecke, Daniel, Moritz Wehking, Jens Friedrichs, and Matthias Binner. "A Method for Forecasting the Condition of Several HPT Parts by Using Bayesian Belief Networks." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43110.
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The competitive ability of jet engine maintenance companies depends mainly on turn around time and overhaul costs. Both airline and maintenance companies need the best possible accuracy regarding the prediction of emerging costs and time of engine maintenance process to secure their operation. Estimating the deterioration status of engine modules prior to disassembling is one of the greatest challenges for the maintenance process. In a pilot project a Bayesian belief network (BBN) has been developed to determine the deterioration condition of the General Electric CF6-80C2 first stage high pressure turbine (HPT) nozzle guide vane (NGV). The aim of this paper is to extend the used BBN techniques to the HPT first and second stage rotor blades and the second stage vanes. Thereby, its objective is to prove the successful application of the developed method for constructing a BBN for component hardware forecast. The BBN is composed of following parameters: component repair history, region, on-wing cycles, airfoil material, thrust rating, engine wing position and customer segment. Performing statistical data analysis and combining these parameters with expert knowledge result in component specific BBNs. These nets provide a moderate forecast accuracy of 59 percent for the first stage rotor blades, 65 percent for the second stage rotor blades and promising 89 percent for the second stage NGVs. The paper concludes that a BBN has very good qualities to forecast the hardware condition of HPT components impressively shown by virtue of the nozzles. Therefore, it is worth to transfer the developed method to other modules in order to accurately predict the degradation of the components in an unconventional way.
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Wrobel, Michal, Mark Richter, Rene Zimmermann, Holger Kiewel, and Andreas Ullrich. "Rotor Lifecycle Management Program." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26761.
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Minimizing the maintenance costs has become an ever growing topic in the power generation industry. Consequently, OEM’s constantly increase their efforts to exploit the full lifetime potential of capital intensive components, as for instance gas turbine rotors. More than ever, it is essential to have a closed loop from the design knowledge to solid facts about the actual condition of a gas turbine rotor in the field, in order to optimize the utilization and therefore to reduce total lifecycle costs. During initial design an iterative component design process is applied, comprising of analytical calculations and component and engine tests, to design a reliable, robust and maintenance friendly component. Individual component risk profiles (i.e. failure probability and consequences) have to be taken into account during the design phase to cover uncertainties regarding the operating regime, operating conditions and environment, resulting in the minimum expected lifetime. The lifetime of gas turbine components is limited and primarily depends on factors like the operating regime, dictating the mechanical and thermal loads, actual material properties, environmental conditions and the level of maintenance. Those parameters have a scatter and also interact with each other. As a consequence the progress of component degradation varies and the individual component lifetime isn’t known in detail at the time of the design. The purpose of a Rotor Lifecycle Management Program is to detect individual component degradation early in the lifecycle, in order to exploit the maximum rotor lifetime while ensuring safe operation. Periodic monitoring and condition assessment of the individual rotor is the first step, performed during standard type C inspections and comprising of visual inspection, dimensional and advanced non-destructive measurements. Typically the monitoring schedule is based on the operating regime and the operating history of the specific rotor. The combination of the monitoring results with validated analytical design models, extensive material data and the overall gas turbine rotor fleet experience of the OEM, allows proper planning of lifetime extension measures, such as repair and reconditioning activities. Specific repair solutions for both on-site and shop applications have been developed. A rotor lifecycle management program is a „living” program. The monitoring scope and schedule as well as the repair solutions portfolio are continuously optimized and adapted as a result of detailed analysis of operating data and inspection results of the whole global fleet.