Academic literature on the topic 'Threshold repair'
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Journal articles on the topic "Threshold repair"
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Sun, Mingjuan, Qinglai Dong, and Zihan Gao. "An Imperfect Repair Model with Delayed Repair under Replacement and Repair Thresholds." Mathematics 10, no. 13 (June 28, 2022): 2263. http://dx.doi.org/10.3390/math10132263.
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Based on the extended geometric process, a repair replacement model of a degradation system is studied, in which the delayed repair time depends on the working time after the last repair. Replacement and repair thresholds describe when the system will be replaced and when the system can be repaired, respectively. Two kinds of replacement policies are studied. One policy is jointly determined by the moment of the Nth failure and the first hitting time of the working time after the last repair for the replacement threshold, and the system is replaced, whichever occurs first; the other is the special case of the first policy, and the system is replaced when the working time after the last repair first hits the replacement threshold. The exact expressions of the long-run average cost rate are obtained. The optimal policies exist and can be ascertained by numerical methods. Finally, numerical examples are presented to demonstrate the application of the results obtained in the paper.
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RANGAN, A., and V. ARUNACHALAM. "A THRESHOLD MODEL FOR CELL SURVIVAL." International Journal of Biomathematics 02, no. 02 (June 2009): 119–27. http://dx.doi.org/10.1142/s1793524509000625.
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This paper deals with a threshold model for gene damages in a cell subject to repair. The damages and repairs are considered to be stochastic events. The status of the cell is partitioned into a number of states representing the number of proliferative gene damages it has suffered. The probability of finding the cell with a certain number of gene damages at any time and the expected number of repairs in an arbitrary interval are obtained.
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Guo, Ting Liang, and Zhao Xing Han. "Repairing Surface Fatigue Damage of the Metal Material by Heat Treatment." Advanced Materials Research 154-155 (October 2010): 425–28. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.425.
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In this paper, using experimental method studied to repair surface fatigue damage of the metal material by heat treatment. Analyzed the mechanism to repair surface fatigue damage of the metal material by heat treatment. From the test, it have been found that the Metal materials has temping threshold behavior in repairing it’s fatigue damage by heat treatment. For the same kind of material, there is a threshold characteristics in choosing tempering temperatures when repaired the fatigue damage of metal material surface through changed tempering temperatures. Experimental results shows that the temping temperature threshold to repair metal material fatigue damage is the first tempering temperature after materials was hardened before it was in fatigue damage.
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Liu, Liren, Jennifer Lee, and Pengbo Zhou. "Navigating the nucleotide excision repair threshold." Journal of Cellular Physiology 224, no. 3 (April 23, 2010): 585–89. http://dx.doi.org/10.1002/jcp.22205.
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Hasegawa, Kunio, Saburo Usami, and Bohumír Strnadel. "Fatigue Crack Growth Thresholds under Negative Stress Ratio for Aluminium Alloys." Key Engineering Materials 810 (July 2019): 34–39. http://dx.doi.org/10.4028/www.scientific.net/kem.810.34.
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When fatigue crack growth rate da/dN = 0, the stress intensity factor range ΔKI is a threshold and it is expressed by ΔKI = ΔKth. The threshold ΔKth is important for design, repair/replacement, particularly, trouble shooting for cracked components. However, the thresholds were not well codified. Authorized and consensus ΔKth are required. This paper introduces the current thresholds provided by fitness-for-service codes and the definition of ΔKth under negative stress ratio R is discussed. Finally, the threshold ΔKth for aluminum alloys in air environment is proposed for fitness-for-service codes.
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Ojobor, S. A., and N. O. Ogini. "Threshold recovery policy for the machine interference repair problem with server vacations." Journal of Physics: Conference Series 2199, no. 1 (February 1, 2022): 012020. http://dx.doi.org/10.1088/1742-6596/2199/1/012020.
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Abstract In this paper, we consider the threshold recovery policy for the machine interference problem (MIP) with server vacations, having a non-dependable server which operates a threshold recovery policy, i.e., service starts after a fixed threshold level q ≥ 1. In the threshold recovery policy, M machines of similar nature are subject to fail or break down with a single server responsible for maintaining or repairing the failed machines. When the server is working, it is subject to breakdown with exponential distribution rate α; it is not possible to repair any server until the number of failed computers exceeds a predetermined threshold, q where 1 ≤ q ≤ M. The repaired rate is exponentially distributed with rate β. The server breaks down with a constant failure rate. The repair and vacation time of server is exponentially distributed. We developed the difference differential equations for the transient state probabilities for the system. We calculate the threshold recovery strategy for the MIP with server vacation using the ODE45 (Runge-Kutta method for solving ordinary differential equations) in the MATLAB computer language. We develop a variety of operational quality metrics for the system.
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Park, Minjae, Ki Mun Jung, and Dong Ho Park. "Optimal post-warranty maintenance policy with repair time threshold for minimal repair." Reliability Engineering & System Safety 111 (March 2013): 147–53. http://dx.doi.org/10.1016/j.ress.2012.10.017.
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Petcherdchoo, Aruz. "Probabilistic Assessment of CO2 due to Concrete Repairs for Crack-Free Condition of Marine Concrete Structures." Advanced Materials Research 931-932 (May 2014): 426–30. http://dx.doi.org/10.4028/www.scientific.net/amr.931-932.426.
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An approach which combines the Latin Hypercube technique with Crank-Nicolson based finite difference approach is developed for probabilistic assessment of chloride diffusion in concrete structures with repairs. Two random variables, i.e., surface chloride and diffusion coefficient, are considered. Four repair strategies are proposed by varying the diffusion coefficient of repair concrete and the repair depth. A repair by cover replacement is applied at a critical time which the chloride content at a threshold depth reaches its critical value for concrete cracking. The critical time is defined as the repair time, which the CO2 due to repair concrete production and replacement processing occurs. By this method, the median of repair time and the probabilistic time-dependent CO2 can be assessed. The mean and the percentiles of cumulative total CO2 are compared.
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Fu, Zhongqiu, Dongyang Wu, Liang Fang, Donghua Chen, and Bohai Ji. "Influence Factors and Repair Effects of Seismic Damage to a Box Section Steel Pier." Journal of Earthquake and Tsunami 13, no. 03n04 (June 2019): 1940001. http://dx.doi.org/10.1142/s1793431119400013.
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The seismic performance of a steel pier of box section was studied through low-cycle cyclic testing. The damaged specimens were repaired by filling with concrete and welding steel plates. The low-cycle cyclic test was then repeated. The effects of repairs were investigated by comparison of failure mode, energy dissipation performance, and ductility before and after repair. To supplement the data, the influence of different factors on the seismic bearing capacity and ductility of steel piers were analyzed by finite element method. The repair effects were compared by threshold of the displacement from the experiment. Based on the displacement angle response of the nonlinear dynamic time history analysis, the seismic performance is checked. The results show that repair had favourable effects on the damaged specimens. The horizontal bearing capacity and ductility of the specimens filled with concrete are significantly enhanced. Reinforcement by steel plates can increase the ductility and cumulative energy dissipation of the steel pier. An axial compression ratio of 0.2 and a concrete filling ratio of 30% are suggested. The horizontal bearing capacity can be improved by increasing the steel strength while the concrete strength shows little effect. The angular displacement from nonlinear dynamic time-history analysis was less than the test threshold, so the existing methods used for seismic performance verification are safe.
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Eid, Mark A., Xavier P. Fowler, Jesse A. Columbo, Bjoern D. Suckow, David H. Stone, and Philip P. Goodney. "Deferred Abdominal Aortic Aneurysm Repair in Patients Who Meet Threshold Criteria for Repair." Journal of Vascular Surgery 75, no. 6 (June 2022): e239. http://dx.doi.org/10.1016/j.jvs.2022.03.486.
Full textDissertations / Theses on the topic "Threshold repair"
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Zhou, Lingzhong, and n/a. "Agent Ordering and Nogood Repairs in Distributed Constraint Solving." Griffith University. School of Information and Communication Technology, 2006. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20070713.162515.
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The distributed constraint satisfaction problem is a general formalization used to represent problems in distributed multi-agent systems. A large body of problems in artificial intelligence and computer science can be easily formulated as distributed constraint satisfaction problems. In this thesis we study agent ordering, effects of no-goods, search efficiency and threshold repairing in distributed constraint satisfaction problems and its variants. A summary of contributions is as follows: 1. We present a new algorithm, Dynamic Agent Ordering. A distinctive feature of this algorithm is that it uses the degree of unsatisfiability as a guiding parameter to dynamically determine agent ordering during the search. We show through an empirical study that our algorithm performs better than the existing approaches. In our approach, the independence of agents is guaranteed and agents without neighbouring relationships can run concurrently and asynchronously. (Part of this work was published in the Australian Al Conference (80)). 2. We extend the Dynamic Agent Ordering algorithm by incorporating a novel technique called nogood repairing. This results in a dramatic reduction in the nogoods being stored, and communication costs. In an empirical study, we11 show that this approach outperforms an equivalent static ordering algorithm and a current state-of-the-art technique in terms of execution time, memory usage and communication cost. (Part of this work was published at FLAIRS Conference (81)). Further, we introduce a new algorithm, Over-constrained Dynamic Agent Ordering, that breaks new ground in handling multiple variables per agent in distributed over-constrained satisfaction problems. The algorithm also uses the degree of unsatisfiability as a measure for relaxing constraints, and hence as a way to guide the search toward the best optimal solution(s). By applying our Threshold Repair method, we can solve a distributed constraint satisfaction problem without knowing whether the problem is under- or over-constrained. In an experimental study, we show that the new algorithm compares favourably to an implementation of asynchronous weak commitment search adapted to handle over-constrained problems. (Part of this work was published at the Canadian AI conference (79)).
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Zhou, Lingzhong. "Agent Ordering and Nogood Repairs in Distributed Constraint Solving." Thesis, Griffith University, 2006. http://hdl.handle.net/10072/365303.
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The distributed constraint satisfaction problem is a general formalization used to represent problems in distributed multi-agent systems. A large body of problems in artificial intelligence and computer science can be easily formulated as distributed constraint satisfaction problems. In this thesis we study agent ordering, effects of no-goods, search efficiency and threshold repairing in distributed constraint satisfaction problems and its variants. A summary of contributions is as follows: 1. We present a new algorithm, Dynamic Agent Ordering. A distinctive feature of this algorithm is that it uses the degree of unsatisfiability as a guiding parameter to dynamically determine agent ordering during the search. We show through an empirical study that our algorithm performs better than the existing approaches. In our approach, the independence of agents is guaranteed and agents without neighbouring relationships can run concurrently and asynchronously. (Part of this work was published in the Australian Al Conference (80)). 2. We extend the Dynamic Agent Ordering algorithm by incorporating a novel technique called nogood repairing. This results in a dramatic reduction in the nogoods being stored, and communication costs. In an empirical study, we11 show that this approach outperforms an equivalent static ordering algorithm and a current state-of-the-art technique in terms of execution time, memory usage and communication cost. (Part of this work was published at FLAIRS Conference (81)). Further, we introduce a new algorithm, Over-constrained Dynamic Agent Ordering, that breaks new ground in handling multiple variables per agent in distributed over-constrained satisfaction problems. The algorithm also uses the degree of unsatisfiability as a measure for relaxing constraints, and hence as a way to guide the search toward the best optimal solution(s). By applying our Threshold Repair method, we can solve a distributed constraint satisfaction problem without knowing whether the problem is under- or over-constrained. In an experimental study, we show that the new algorithm compares favourably to an implementation of asynchronous weak commitment search adapted to handle over-constrained problems. (Part of this work was published at the Canadian AI conference (79)).Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Information and Communication Technology
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Takeno, Katsumi. "Neuromuscular Function of the Shoulder Girdle and Upper Extremity Muscles in Individuals with Glenohumeral Labral Repair." University of Toledo / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1596111099423871.
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Cheng, Chiung-Yao, and 鄭群耀. "The contract pricing and repair policy of the maintenance contractor for extended warranty under repair time threshold." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/43194976828756132974.
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碩士中原大學
工業與系統工程研究所
104
This study investigates the repair cost model and the service contract pricing model of the maintenance contractor for the product sold with the extended warranty. This study believes the repair time, dealing with the failures of product, which can affect the customer satisfaction in the current market. Therefore, this study incorporates the repair time threshold in cost model. Besides, this study takes fixed price to make long-term collaboration between the maintenance contractor and the manufacturer in our service contract pricing model. Furthermore, we add the discount rate to build the optimal pricing model in this study. Then we can understand how long of the extended warranty service contract signed by the maintenance contractor sign with the manufacturer when manufacturer provides extended warranty to consumer. Although the three repair-time thresholds all obtain the same length of warranty in the result, the repair time threshold and maintainability also influence the cost of maintenance contractor. The future study can add the customer satisfaction or the standard time requested by the manufacturer together with the repair time threshold to build mathematical model.
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Chang, Wen-Liang, and 張文亮. "Optimal Maintenance Policies for Leased Equipment under Different Threshold Values for Repair." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/agb3ka.
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博士國立臺灣科技大學
工業管理系
95
For multi-function products, manufacturers may need different types of machine equipment to produce them. However, the maintenance of machine equipment usually requires special professional technicians, which is not economical for manufacturers to own a professional maintenance group. For cost reduction, manufacturers tend to lease machine equipment instead of buying them. Therefore, the lease companies have been developed. For the failure-rate/age feature of the leased equipment/goods, the lease company and manufacturers may sing a lease contract which includes the leased period, preventive maintenance (PM) time, tolerance time of repair and penalty cost. This thesis proposes that the lease company performs PM actions when the failure rate/age of equipment reaches a threshold value in order to reduce the lease company's maintenance cost and the manufacturer's production cost caused by equipment failures. The age-reduction and failure-rate-reduction methods of PM are adopted to prevent equipment failure and maintain the operational state of the equipment in order to produce the products with good quality. For the failure rate and age characteristic of the leased equipment and the length of lease period, this thesis proposes four major topics to investigate the optimal PM policy for the leased equipment within the lease period: (i) single-phase model under age-reduction method (ARM), (ii) two-phase model under ARM, (iii) single-phase model under failure-rate-reduction method (FRRM) and (iv) two-phase model under FRRM.
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Shih, Han-Ching, and 施涵晴. "Optimization analysis of retrial machine repair system with server breakdown and threshold recovery policy." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/q9ez8r.
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碩士國立中興大學
應用數學系所
106
Queue theory, which can analyzes the resources needed to provide a service, is very helpful for operating decisions. With the advances in technology, the application of Queue theory has become more and more extensive, including queuing from reality to virtual. To improve both quality and cost of service, Queue theory is an important analytic method. Cloud computing has gained lots of popularity in recent years. A Virtual Machine is a software installed in a virtual storage, which provides cloud SaaS service. Virtual Machines shift the deployment of computing infrastructure from end users to the cloud data center. Users can get the service via the Internet, requiring no hardware devices on the client''s side. Cloud computing administrative tools can create, manage, and deploy cloud services, such as CloudStack. We wonder how cloud computing administrative tools could operate with Queue theory. This paper explores optimization analysis of retrial machine repair system with server breakdown and threshold recovery policy. There are operating machines with warm standby machines, and a repairman in the system. The repairman can repair only one machine at a time. If the repairman is busy, the failed machine will be transmitted to the retrial orbit to wait for check. When the number of failed machines in the system accumulates to the predefined threshold , the system would fix the repairman or failed machines. At first, we build up the state-transition-rate diagram and steady-state equations. And then, we calculate the steady-state probabilities and system performance measures by Maple software. Consider system performance measures to define the cost function , where is a discrete variable and , and are continuous variables and . We find the optimal value by using the direct search method, then find the minimum value by using two-stage optimization method. is the minimum cost value.
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Chiang, Ya-Chu, and 江雅筑. "Using Particle Swarm Optimization Algorithm to Analyze the Machine Repair Problem with Threshold-based Recovery Policy." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/45277755907301925167.
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碩士國立臺北商業技術學院
資訊與決策科學研究所
100
This thesis investigates a machine repair problem in which identical machines are maintained by an unreliable server (repairman). When there are no failed machines in the system, the server leaves for a vacation of random length. Upon returning from vacation, the server immediately takes another vacation if there are no failed machines in the system. The server is subject to breakdown and implements a threshold-based recovery policy, which means that when the server breaks down, it would not be repaired until at least q machines fail (1≤q≤M). The failure and service times of each machine and the breakdown, repair and vacation times of the server, are all assumed to be exponentially distributed. To obtain neat closed-form expressions for the steady-state probability distributions of failed machines in the system, a recursive method is employed. In addition, we derive important system characteristics, such as the expected number of failed machines in the system, machine availability, operative utilization and system availability. The expected profit per machine per unit time is constructed to determine the optimal threshold value, optimal service rate, optimal vacation rate and optimal repair rate. To this end, we apply the particle swarm optimization algorithm to solve this optimization problem while maintaining system availability at a certain level. Finally, a sensitivity analysis is also conducted to evaluate the effects of system parameters and cost elements on the optimal solutions.
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Aramon, Bajestani Maliheh. "Integrating Maintenance Planning and Production Scheduling: Making Operational Decisions with a Strategic Perspective." Thesis, 2014. http://hdl.handle.net/1807/65637.
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In today's competitive environment, the importance of continuous production, quality improvement, and fast delivery has forced production and delivery processes to become highly reliable. Keeping equipment in good condition through maintenance activities can ensure a more reliable system. However, maintenance leads to temporary reduction in capacity that could otherwise be utilized for production. Therefore, the coordination of maintenance and production is important to guarantee good system performance. The central thesis of this dissertation is that integrating maintenance and production decisions increases efficiency by ensuring high quality production, effective resource utilization, and on-time deliveries.
Firstly, we study the problem of integrated maintenance
and production planning where machines are preventively maintained in the context of a periodic review production system with uncertain yield. Our goal is to provide insight into the optimal maintenance policy, increasing the number of finished products. Specifically, we prove the conditions that guarantee the optimal maintenance policy has a threshold type.
Secondly, we address the problem of integrated maintenance
planning and production scheduling where machines are correctively maintained in the context of a dynamic aircraft repair shop. To solve the problem, we view the dynamic repair shop as successive static repair scheduling sub-problems over shorter periods. Our results show that the approach that uses logic-based Benders decomposition to solve the static sub-problems, schedules over longer horizon, and quickly adjusts the schedule increases the utilization of aircraft in the long term.
Finally, we tackle the problem of integrated maintenance planning and production scheduling where machines are preventively maintained in the context of a multi-machine production system. Depending on the deterioration process of machines, we design decomposed techniques that deal with the stochastic and combinatorial challenges in different, coupled stages. Our results demonstrate that the integrated approaches decrease the total maintenance and lost production cost, maximizing the on-time deliveries. We also prove sufficient conditions that guarantee the monotonicity of the optimal maintenance policy in both machine state and the number of customer orders.
Within these three contexts, this dissertation demonstrates that the integrated maintenance and production decision-making increases the process efficiency to produce high quality products in a timely manner.
Books on the topic "Threshold repair"
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Office, General Accounting. Financial management: Survey of capitalization threshold and other policies for property, plant, and equipment : report to Agency officials. Washington, D.C: U.S. General Accounting Office, 2002.
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Financial management: DOD needs to lower the disbursement prevalidation threshold : report to congressional requesters. Washington, D.C: The Office, 1996.
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Lefroy, Ted, Allan Curtis, Anthony Jakeman, and James McKee, eds. Landscape Logic. CSIRO Publishing, 2012. http://dx.doi.org/10.1071/9780643103559.
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In 2005, researchers from four Australian universities and CSIRO joined forces with environmental managers from three state agencies and six regional catchment management authorities to answer the question: 'Can we detect the influence of public environmental programs on the condition of our natural resources?' This was prompted by a series of national audits of Australia's environmental programs that could find no evidence of public investment improving the condition of waterways, soils and native vegetation, despite major public programs investing more than $4.2 billion in environmental repair over the last 20 years.
Landscape Logic describes how this collaboration of 42 researchers and environmental managers went about the research. It describes what they found and what they learned about the challenge of attributing cause to environmental change. While public programs had been responsible for increase in vegetation extent, there was less evidence for improvement in vegetation condition and water quality. In many cases critical levels of intervention had not been reached, interventions were not sufficiently mature to have had any measurable impact, monitoring had not been designed to match the spatial and temporal scales of the interventions, and interventions lacked sufficiently clear objectives and metrics to ever be detectable. In the process, however, new knowledge emerged on disturbance thresholds in river condition, diagnosing sources of pollution in river systems, and the application and uptake of state-and-transition and Bayesian network models to environmental management.
The findings discussed in this book provide valuable messages for environmental managers, land managers, researchers and policy makers.
Book chapters on the topic "Threshold repair"
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Hausleitner, Birgit, Adrian Hill, Teresa Domenech, and Victor Muñoz Sanz. "Urban Manufacturing for Circularity: Three Pathways to Move from Linear to Circular Cities." In Regenerative Territories, 89–103. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-78536-9_5.
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AbstractUrban manufacturing and manufacturers play a vital role in delivering circular economy ambitions through processing materials, providing skills and technology for repair or reconditioning goods and the capacity to deliver innovative technology. The transdisciplinary approach of Cities of Making (CoM) puts forward three ways of addressing manufacturing, and by extension, circularity, within urban areas. Central to triangulate the facilitation of urban manufacturing are the perspectives of (1) material flows and technology, (2) spatial design (3) people and networks. The integration of the three pathways requires convergence while retaining the richness of the three perspectives. The challenge is to find a common language that provides a comparable, operative framework for exploring possible solutions. The CoM framework of integration followed three main principles: (1) reducing the complexity of information, (2) reducing the complexity of combinations of possible solutions, and (3), applying an accessible, applicable instrument for the solutions. The resulting pattern language is co-created in a transdisciplinary setting and is also an instrument for the transdisciplinary application. The low threshold accessible system of solutions allows actors from different disciplines to access patterns developed in the context of another discipline and laypeople who are affected or interested to co-create.
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Gocke, Elmar, Thomas Singer, and Lutz Müller. "DNA Alkylation and Repair After EMS Exposure: Where Do the Thresholds for Mutagenic/Clastogenic Effects Arise?" In The Cellular Response to the Genotoxic Insult, 52–62. Cambridge: Royal Society of Chemistry, 2012. http://dx.doi.org/10.1039/9781849732925-00052.
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"Testing of the chloride threshold values for reinforced concrete structures." In Concrete Repair, Rehabilitation and Retrofitting III, 209–10. CRC Press, 2012. http://dx.doi.org/10.1201/b12750-85.
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"The effect of binder type on chloride threshold values for reinforced concrete." In Concrete Repair, Rehabilitation and Retrofitting III, 61–62. CRC Press, 2012. http://dx.doi.org/10.1201/b12750-15.
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"Service life extension of concrete structures by increasing chloride threshold using stainless steel reinforcements." In Concrete Repair, Rehabilitation and Retrofitting III, 202–4. CRC Press, 2012. http://dx.doi.org/10.1201/b12750-82.
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Park, Minjae, Ki Mun Jung, and Dong Ho Park. "Two-Dimensional Maintenance with Repair Time Threshold and Generalized Age Replacement Policy." In Reliability Modeling with Computer and Maintenance Applications, 295–311. WORLD SCIENTIFIC, 2017. http://dx.doi.org/10.1142/9789813224506_0015.
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Edgerton, V. Reggie, Roland R. Roy, Daniel C. Lu, and Yury Gerasimenko. "Animal models of damage, repair, and plasticity in the spinal cord." In Oxford Textbook of Neurorehabilitation, 135–47. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199673711.003.0013.
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Sensorimotor function can improve for years, even after a spinal cord injury (SCI). We also know that an effective intervention that can improve motor function is re-engagement of the spinal neural networks and that this regularity in re-engagement is fundamental to learning within the activated sensorimotor circuits. Several interventions have been developed allowing individuals with a SCI to re-engage sensorimotor circuits. These interventions enable spinal neural circuits to neuromodulatethe level of excitability closer to a near motor threshold state.This is because of the built-in level of automaticity within the spinal circuits that then is translated into motor commands specified by the sensory input. Another increasingly apparent feature of the spinal circuitry is the highly integrated nature of multiple physiological systems linked to load bearing sensory input. Thus it is clear that multiple physiological systems are highly responsive to activity-dependent interventions after a severe SCI and that this responsiveness can persist for years post-injury.
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Freund, Patrick, V. Reggie Edgerton, Roland R. Roy, Daniel C. Lu, and Yury Gerasimenko. "Animal models of damage, repair, and plasticity in the spinal cord." In Oxford Textbook of Neurorehabilitation, edited by Volker Dietz, Nick S. Ward, and Christopher Kennard, 155–68. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780198824954.003.0013.
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Sensorimotor function can improve for years, even after a spinal cord injury (SCI). We also know that an effective intervention that can improve motor function is re-engagement of the spinal neural networks through supraspinal control and that this regularity in re-engagement is fundamental to learning within the activated sensorimotor circuits. Several interventions, ranging from monoclonal antibodies against neurit outgrowth inhibitors to epidural electrical stimulation, have been developed allowing individuals with a SCI to re-engage sensorimotor circuits. These interventions enable spinal neural circuits to neuromodulate the level of excitability closer to a near motor threshold state. This is because of the built-in level of automaticity within the spinal circuits that then is translated into motor commands specified by the sensory input. Another increasingly apparent feature of the spinal circuitry is the highly integrated nature of multiple physiological systems linked to load bearing sensory input. Thus, it is clear that multiple physiological systems are highly responsive to activity-dependent interventions after a severe SCI and that this responsiveness can persist for years post-injury and be therapeutically modulated.
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Alnowibet, Khalid, and Lotfi Tadj. "Analysis of Two Phases Queue With Vacations and Breakdowns Under T-Policy." In Advances in Marketing, Customer Relationship Management, and E-Services, 13–31. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7766-9.ch002.
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The service system considered in this chapter is characterized by an unreliable server. Random breakdowns occur on the server and the repair may not be immediate. The authors assume the possibility that the server may take a vacation at the end of a given service completion. The server resumes operation according to T-policy to check if enough customers have arrived while he was away. The actual service of any arrival takes place in two consecutive phases. Both service phases are independent of each other. A Markov chain approach is used to obtain the steady state system size probabilities and different performance measures. The optimal value of the threshold level is obtained analytically.
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Alnowibet, Khalid, and Lotfi Tadj. "Analysis of Two Phases Queue With Vacations and Breakdowns Under T-Policy." In Encyclopedia of Information Science and Technology, Fourth Edition, 1570–83. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-2255-3.ch136.
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The service system considered in this chapter is characterized by an unreliable server. Random breakdowns occur on the server and the repair may not be immediate. We assume the possibility that the server may take a vacation at the end of a given service completion. The server resumes operation according to T-policy to check if enough customers have arrived while he was away. The actual service of any arrival takes place in two consecutive phases. Both service phases are independent of each other. A Markov chain approach is used to obtain the steady state system size probabilities and different performance measures. The optimal value of the threshold level is obtained analytically.
Conference papers on the topic "Threshold repair"
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"Concrete Repair at the Threshold of the 21st Century: Focus on Strengthening of Existing Structures." In SP-185: High-Performance Fiber Reinforced Concrete in Infrastructural Repair and Retrofit. American Concrete Institute, 2000. http://dx.doi.org/10.14359/5714.
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Sabbaghi, Mostafa, and Sara Behdad. "Environmental Impact Assessment of Product Lifespan: The Role of Consumer’s Repair Behavior and Critical Components Deterioration." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-59321.
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Consumers might be willing to repair their broken devices as long as the associated repair costs do not exceed an undesirable threshold. However, in many cases the technological obsolescence actuates consumers to retire old devices and replace them with new ones rather than extending the product lifecycle through repair. In this paper, we aim to investigate the impact of components’ deterioration profiles and consumers’ repair decisions on the lifespan of devices, and then assesse the anticipated life cycle environmental impacts. A Monte Carlo simulation is developed to estimate the life cycle characteristics such as the average lifespan, the number of failed components’ replacement, and the total repair cost per cycle for a laptop computer. The lifecycle characteristics estimated from simulation model further have been used in a Life Cycle Assessment (LCA) study to quantify the environmental impact associated with different design scenarios. The results reveal the impact of product design as well as consumers’ repair decisions on the product lifespan and the corresponding environmental impacts.
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Sheets, Colton, Robert Rettew, Chris Alexander, and Tanya Axenova. "Full-Scale Elevated Temperature Testing of Composite Repairs in Bending and Compression." In 2016 11th International Pipeline Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/ipc2016-64213.
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The increasing use of composite repair systems in critical and complex applications has brought greater scrutiny to their design and performance. This has been especially true in high-temperature, immersed environment applications where ambient temperature test results with industry standard de-rating factors are all that is available for design. Since this approach does not always adequately capture environmental effects or the performance of composite systems at elevated temperatures, it is beneficial to perform full-scale testing which accurately replicates the in-situ application. In order to accomplish this, a full-scale testing program was developed that subjected multiple composite repair systems to internal and external loads at temperatures up to 120 °C with and without water immersion. This program involved the reinforcement of 12.75-inch × 0.375-inch pipe samples that had simulated corrosion defects. Full-scale load and pressure testing was conducted to simulate the long-term performance of the composite repair systems in the environmental conditions of the application. A strain based performance threshold of 0.4% strain at 120 °C and 100% SMYS was used to develop a competitive program that ranked the participating systems and reduced the number of acceptable repairs from six down to three. This approach increased the efficiency of the full-scale testing and allowed for more in-depth analysis of the top-performing systems. The results of the full-scale testing of six composite repair systems at elevated temperature allowed for a quantitative measure of their effectiveness under in-situ conditions. Several of the systems were shown to provide inadequate reinforcement under these conditions; however, it was also observed that appropriately designed and installed systems are capable of meeting the intense demands of elevated temperature, harsh-service conditions.
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Sheets, Colton, Taylor Shie, and Adam Crawford. "Thin-Wall Pipeline Repair: Evaluation of Reinforcement Systems and Internal Temperature Monitoring During Maintenance Procedures." In 2018 12th International Pipeline Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/ipc2018-78647.
Full textAbstract:
There are many options available to pipeline operators when addressing anomalies or integrity threats. Repairing integrity threats requires an understanding of both the anomaly to be repaired, and the repair system itself. This can be challenging as pipeline repair systems come in a wide variety of materials, application techniques, and designs. Operators have similar challenges when performing maintenance activities on operating pipelines. Maintenance activities can take many different forms and often involve welding or other high temperature processes on the outside pipe surface. These processes can result in elevated temperatures on the inside surface of the pipeline and must be seriously considered before undertaking to ensure the safety of personnel performing the tasks and to protect the integrity of the pipeline. This study aimed to provide a greater understanding of pipeline reinforcement systems and maintenance activities as they relate specifically to thin-walled pipelines. To evaluate systems reinforcing thin-wall pipes, five different repair systems were investigated using 12.75-inch × 0.219-inch, Gr. X65 pipe that had been removed from service. The systems included a Type B steel sleeve, an epoxy-filled, interference fit, Type A steel sleeve, a hybrid steel sleeve-fiberglass based composite repair system, epoxy-filled oversized Type A steel sleeves, and a rigid coil, pre-cured, fiberglass-based composite repair system. Each system was used to reinforce a simulated 50% wall loss anomaly and was installed with the pipe samples maintained at an internal pressure equal to 33% of the pipe’s specified minimum yield strength (SMYS). The samples underwent pressure cycling and hydrostatic testing while strains in the simulated wall loss region were continually monitored. As a final step, the samples were burst tested. Monitoring of strain gages installed in the simulated wall loss anomaly allowed for comparisons to be made between the tested repair systems. It was observed that the recorded strain magnitudes and strain ranges were higher in some samples than others during testing. This allowed the systems to be ranked according to the recorded strains. Although differences were observed in the recorded strains, burst testing showed that all reinforcement systems were able to force failure to the base pipe outside of the simulated wall loss region. Maintenance procedures were also evaluated to identify those that could produce unacceptable temperatures on the inside surface of the thin-wall pipe. The maintenance procedures included installation of Type A steel sleeves (non-pressure containing), Type B steel sleeves (pressure containing), cad welds, and pin brazing cathodic protection (CP) test leads. Temperatures were monitored on the internal pipe surface using thermocouples and an infrared (IR) camera while the maintenance procedures were being performed. An internal surface temperature of 500 °F (260 °C) was set as the threshold for suitability. Monitoring of the Type B steel sleeve installation showed temperatures on the inside surface of the pipe that exceeded 1,200 °F (648 °C) when performing the circumferential weld at each end of the steel sleeve. A maximum temperature of 280 °F (137 °C) was recorded when making the longitudinal welds that included a backing strip. For the application being considered, this indicated that Type A steel sleeves (longitudinal welds only) could be installed within the required temperature limits. A maximum internal temperature of 936 °F (502 °C) was recorded during cad-welding. Pin-brazing was slightly lower, but also exceeded the 500 °F threshold. This testing confirmed that the installation of Type B steel sleeves, cad welding, or pin brazing should receive scrutiny before being performed on operating thin-wall pipelines.
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Hooghan, K. N., K. S. Wills, P. A. Rodriguez, and S. J. O’Connell. "Integrated Circuit Device Repair Using FIB System: Tips, Tricks, and Strategies." In ISTFA 1999. ASM International, 1999. http://dx.doi.org/10.31399/asm.cp.istfa1999p0247.
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Abstract Device repair using Focused Ion Beam(FIB) systems has been in use for most of the last decade. Most of this has been done by people who have been essentially self-taught. The result has been a long learning curve to become proficient in device repair. Since a great deal of the problem is that documentation on this “art form” is found in papers from many different disciplines, this work attempts to summarize all of the available information under one title. The primary focus of FIB device repair is to ensure and maintain device integrity and subsequently retain market share while optimizing the use of the instrument, usually referred to as ‘beam time’. We describe and discuss several methods of optimizing beam time. First, beam time should be minimized while doing on chip navigation to reach the target areas. Several different approaches are discussed: dead reckoning, 3-point alignment, CAD-based navigation, and optical overlay. Second, after the repair areas are located and identified, the desired metal levels must be reached using a combination of beam currents and gas chemistries, and then filled up and strapped to make final connections. Third, cuts and cleanups must be performed as required for the final repair. We will discuss typical values of the beam currents required to maintain device integrity while concurrently optimizing repair time. Maintaining device integrity is difficult because of two potentially serious interactions of the FIB on the substrate: 1) since the beam consists of heavy metal ions (typically Gallium) the act of imaging the surface produces some physical damage; 2) the beam is positively charged and puts some charge into the substrate, making it necessary to use great care working in and around capacitors or active areas such as transistors, in order to avoid changing the threshold voltage of the devices. Strategies for minimizing potential damage and maximizing quality and throughput will be discussed.
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Hazelwood, Scott J., R. Bruce Martin, Juan J. Rodrigo, and Mark M. Rashid. "A Mathematical Model for Bone Remodeling." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0431.
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Abstract A bone remodeling algorithm based on disuse and damage repair was developed in this study. Important elements of the bone remodeling process, including the delay between resorption and formation of bone and the resulting porosity, were included in the algorithm. A study of the dynamic response of the algorithm indicated oscillatory behavior for disuse situations and critically sensitive behavior in overload situations beyond a threshold load. Application of the algorithm to a finite element model of the femur reproduced the observed internal structure. The model is being used in further studies to investigate remodeling around implant stems and bone diseases and their treatment.
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Nowak, Michael, Mick Joseph, Carl Nissen, and Takafumi Asaki. "Proprioception Evaluation of Patients Undergoing Anterior Shoulder Stabilization." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-59703.
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This paper presents the initial data from the first clinical usage of a 2nd generation device to measure proprioception of the shoulder or knee. The device was used to evaluate the surgical stabilization of subjects with anterior shoulder instability. Two types of shoulder proprioception were evaluated: Threshold to Detection of Passive Motion (TTDPM) and Reproduction of Passive Position (RPP). Data is presented for 12 subjects 1 year post-surgery. The data demonstrated that the involved limb TTDPM and RPP approached that of the uninvolved limb, and that the values improved as the shoulder was rotated upwards. Both results point to the efficacy of the repair method and the ability of the device to evaluate proprioception.
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Prueter, Phillip E., and Brian Macejko. "Establishing Recommended Guidance for Local Post Weld Heat Treatment Configurations Based on Thermal-Mechanical Finite Element Analysis." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63581.
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Post weld heat treatment (PWHT) is an effective way to minimize weld residual stresses in pressure vessels and piping equipment. PWHT is required for carbon steels above a Code-defined thickness threshold and other low-alloy steels to mitigate the propensity for crack initiation and ultimately, brittle fracture. Additionally, PWHT is often employed to mitigate stress corrosion cracking due to environmental conditions. Performing local PWHT following component repairs or alterations is often more practical and cost effective than heat treating an entire vessel or a large portion of the pressure boundary. In particular, spot or bulls eye configurations are often employed in industry to perform PWHT following local weld repairs to regions of the pressure boundary. Both the ASME Boiler and Pressure Vessel (B&PV) Code and the National Board Inspection Code (NBIC) permit the use of local PWHT around nozzles or other pressure boundary repairs or alterations. Additionally, Welding Research Council (WRC) Bulletin 452 [1] offers detailed guidance relating to local PWHT and compares some of the Code-based methodologies for implementing local PWHT on pressure retaining equipment. Specifically, local PWHT methodologies provided in design Codes: ASME Section VIII Division 1 [2] and Division 2 [3], ASME Section III Subsection NB [4], British Standard 5500 [5], Australian Standard 1210 [6], and repair Codes: American Petroleum Institute (API) 510 [7] and NBIC [8] are discussed and compared in this study. While spot PWHT may be appropriate in certain cases, if the soak, heating, and gradient control bands are not properly sized and positioned, it can lead to permanent vessel distortion or detrimental residual stresses that can increase the likelihood of in-service crack initiation and possible catastrophic failure due to unstable flaw propagation. It is essential to properly engineer local or spot PWHT configurations to ensure that distortion, cracking of adjacent welds, and severe residual stresses are avoided. In some cases, this may require advanced thermal-mechanical finite element analysis (FEA) to simulate the local PWHT process and to predict the ensuing residual stress state of the repaired area. This paper investigates several case studies of local PWHT configurations where advanced, three-dimensional FEA is used to simulate the thermal-mechanical response of the repaired region on a pressure vessel and to optimize the most ideal PWHT arrangement. Local plasticity and distortion are quantified using advanced non-linear elastic-plastic analysis. Commentary on the ASME and NBIC Code-specified local PWHT requirements is rendered based on the detailed non-linear FEA results, and recommended good practice for typical local PWHT configurations is provided. Advanced computational simulation techniques such as the ones employed in this investigation offer a means for analysts to ensure that local PWHT configurations implemented following equipment repairs will not lead to costly additional damage, such as distortion or cracking that can ultimately prolong equipment downtime.
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McCracken, Steve. "Fatigue Strength of Socket Welds Repaired by Structural Weld Overlay: Reference ASME Section XI Code Case N-666." In ASME 2005 Pressure Vessels and Piping Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pvp2005-71482.
Full textAbstract:
ASME Code Case N-666 provides alternative rules for repair of a cracked and leaking small bore socket weld by installation of a structural weld overlay [1]. The crack is not removed but is encapsulated and sealed under the weld overlay. Vibration fatigue testing reported by the Electric Power Research Institute (EPRI) demonstrates that socket welds repaired by the method specified in ASME Code Case N-666 have equivalent or better fatigue strength compared to standard socket welds. This paper investigates fatigue test data and fracture mechanics analyses for standard socket welds and compares this to the vibration fatigue strength exhibited by overlay repaired socket welds. A relationship based on fatigue testing of a standard socket weld with root defects was proposed by Japanese researchers to correlate the reduction in fatigue strength with increasing root defect size. This relationship is compared to an EPRI finite element model that was developed to evaluate the stress intensity factor at the root of a standard socket weld. A correction factor is proposed for estimation of the stress intensity factor at the crack tip of a socket weld repaired by weld overlay. The correction factor is derived from a three-dimensional solution for straight pipe with an inside surface circumferential crack and from the finite element model for standard sized socket welds. Finally, weld residual stress analyses reported by Japanese researchers for standard socket welds are compared to weld residual stress data from recent thermal-mechanical finite element analyses for overlay repaired socket welds. The threshold for fatigue crack propagation and the influence of weld residual stress is presented to explain the high vibration fatigue strength exhibited by socket welds repaired by the method of Code Case N-666.
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Cai, Yuecheng, and Jasmin Jelovica. "Structural Optimization of Ships: Benchmark Study of Metaheuristic Algorithms and Constraint Handling Approaches." In ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-79199.
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Abstract Optimization of ship structures can be performed using swarm and evolutionary algorithms in search for global optima, which is useful to maximize performance and minimize costs. There is a wide variety of such algorithms available and some have been proposed recently, but tested on mathematical problems. Thus, a benchmark study is performed here to assess their performance on structural optimization of a 180 m long chemical tanker which needs to fulfil class society’s requirements. Main frame is optimized considering firstly structural weight as a single objective and secondly weight and deck adequacy as two concurrent objectives. Optimization of deck adequacy leads to decrease of stresses in the deck. Artificial neural network is used as surrogate model to reduce the computational time. Following swarm and evolutionary algorithms are considered: PSO, NSGA-II, MOEA/D, MVO, MOMVO, MOGWO, IGWO and GSA. Following constraint handling techniques (CHTs) are used within: static and dynamic penalty, adaptive threshold and repair method. All algorithms are run for 30 times and the statistical results are presented. Results are compared in terms of objective values and speed of convergence. Results reveal that recently proposed swarm algorithms perform worse than well-known evolutionary algorithms in terms of the convergence rate and spread of the non-dominated front. In addition, algorithms’ performance is strongly influenced by CHT used. Among the ones tested, the best CHT is the repair method.
Reports on the topic "Threshold repair"
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Huijser, MP, J. W. Duffield, C. Neher, A. P. Clevenger, and T. Mcguire. Final Report 2022: Update and expansion of the WVC mitigation measures and their cost-benefit model. Nevada Department of Transportation, October 2022. http://dx.doi.org/10.15788/ndot2022.10.
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This report contains an update and an expansion of a cost-benefit model for wildlife-vehicle collisions and associated mitigation measures along highways, that was originally calculated in 2007 US$ and published in 2009. The direct cost values (vehicle repair, human injuries, human fatalities) were updated for deer, elk, and moose, and expanded by including additional species: gray wolf (Canis lupus), grizzly bear (Ursus arctos), and free ranging or feral domesticated species including cattle, horse, and burro. The costs associated with collisions were also expanded by including passive use, or nonuse values associated with the conservation value of selected wild animal species. The total costs (in 2020 US$) associated with a collision with deer, elk and moose were about 2-3 times (direct costs only) or about 3-4 times higher (direct costs and passive use values combined) compared to the values in 2007 US$. The passive use costs associated with threatened species (wolf, grizzly bear) were higher or much higher than the direct costs. The costs associated with mitigation measures (especially fences and wildlife crossing structures) were also updated and supplemented with new data. New cost-benefit analyses generated updated or entirely new threshold values for deer, elk, moose, and grizzly bear. If collisions with these large wild mammal species reach or surpass the threshold values, it is economically defensible to install the associated type and combination of mitigation measures, both based on direct use and passive use parameters and their associated values. The trend in increasing costs associated with vehicle repair costs, costs associated with human injuries and fatalities, and through including passive use values for wildlife is that we learn that the implementation of effective mitigation measures can be considered earlier and more readily than based on the cost-benefit model published in 2009.