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Competitive solutions for online financial problems
 ACM Comput. Surv
, 1998
"... This article surveys results concerning online algorithms for solving problems related to the management of money and other assets. In particular, the survey focuses on search, replacement, and portfolio selection problems. ..."
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This article surveys results concerning online algorithms for solving problems related to the management of money and other assets. In particular, the survey focuses on search, replacement, and portfolio selection problems.
Nearly Optimal Competitive Online Replacement
"... This paper studies the following online replacement problem. There is a real function f(t), called the flow rate, defined over a finite time horizon [0; T ]. It is known that m f(t) M for some reals 0 m ! M . At time 0 an online player starts to pay money at the rate f(0). At each time 0 ! t T ..."
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This paper studies the following online replacement problem. There is a real function f(t), called the flow rate, defined over a finite time horizon [0; T ]. It is known that m f(t) M for some reals 0 m ! M . At time 0 an online player starts to pay money at the rate f(0). At each time 0 ! t T the player may changeover and continue paying money at the rate f(t). The complication is that each such changeover incurs some fixed penalty. The player is called online as at each time t the player knows f only over the time interval [0; t]. The goal of the player is to minimize the total cost comprised of cumulative payment flow plus changeover costs. This formulation of the replacement problem has various interesting applications among which are: equipment replacement, supplier replacement, the menu cost problem and mortgage refinancing.
On Replacement Models Via A Fuzzy Set Theoretic Framework
 IEEE Transactions On Systems Man And Cybernetics Part C: Applications And Reviews, vol 28, no 4, p 549
, 1998
"... Abstract  Uncertainty is present in virtually all replacement decisions due to unknown future events, such as revenue streams, maintenance costs, and in°ation. Fuzzy sets provide a mathematical framework for explicitly incorporating imprecision into the decision making model, especially when the sy ..."
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Abstract  Uncertainty is present in virtually all replacement decisions due to unknown future events, such as revenue streams, maintenance costs, and in°ation. Fuzzy sets provide a mathematical framework for explicitly incorporating imprecision into the decision making model, especially when the system involves human subjectivity. This paper illustrates the use of fuzzy sets and possibility theory to explicitly model uncertainty in replacement decisions via fuzzy variables and fuzzy numbers. In particular, a fuzzy set approach to economic life of an asset calculation as well as a ¯nite horizon single asset replacement problem with multiple challengers is discussed. Because the use of triangular fuzzy numbers provides a compromise between computational ef¯ciency and realistic modeling of the uncertainty, this discussion emphasizes fuzzy numbers. The algorithms used to determine the optimal replacement policy incorporate fuzzy arithmetic, dynamic programming with fuzzy rewards, the vertex method, and various ranking methods for fuzzy numbers. A brief history of replacement analysis, current conventional techniques, the basic concepts of fuzzy sets and possibility theory, and the advantages of the fuzzy generalization are also discussed.
1 Bus Fleet Type and Age Replacement Optimization: A case study utilizing King County Metro fleet data
"... Bus fleet data have consistently shown that vehicle operating and maintenance costs increase as vehicles age. A fleet manager has to deal with the tradeoff between the lower operating and maintenance costs of newer fleets and their higher initial capital costs as well as the tradeoff between convent ..."
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Bus fleet data have consistently shown that vehicle operating and maintenance costs increase as vehicles age. A fleet manager has to deal with the tradeoff between the lower operating and maintenance costs of newer fleets and their higher initial capital costs as well as the tradeoff between conventional and fuel efficient bus technologies. This study formulates and implements a fleet replacement optimization framework that is applied to a case study that compares two bus types: a conventional diesel and a hybrid bus. Employing realworld bus fleet data from King County Metro (Washington State, USA) multiple scenarios are examined to account for uncertainty and variability in the model parameters. In addition sensitivity analyses are performed to study the impacts of parameter values on optimal replacement policies and the permile costs. Key findings include: the Federal Transit Administration (FTA) purchase cost subsidy has the highest impact on the optimal replacement policies; without FTA subsidy it is always cost effective to adopt diesel buses and replace them every 20 years. With an 80 % purchase cost FTA subsidy, hybrid buses are the best choice; the optimal hybrid bus replacement cycle decreases from 18 to 14 years with increasing annual utilizations and operating and maintenance costs or decreasing hybrid purchase price and fuel economy. Fuel price, emissions costs, and initial bus age have little impact on optimal replacement policies. However, discount rate and diesel bus price, annual utilization (in 0 % FTA subsidy scenario) and fuel price (in 80 % FTA subsidy scenario) have the highest impacts on permile costs.
Opportunities and Challenges
"... The Transportation Research Forum, founded in 1958, is an independent, nonprofit organization of transportation professionals who conduct, use, and benefit from research. Its purpose is to provide an impartial meeting ground for carriers, shippers, government officials, consultants, university resea ..."
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The Transportation Research Forum, founded in 1958, is an independent, nonprofit organization of transportation professionals who conduct, use, and benefit from research. Its purpose is to provide an impartial meeting ground for carriers, shippers, government officials, consultants, university researchers, suppliers, and others seeking exchange of information and ideas related to both passenger and freight transportation. More information on the Transportation Research Forum can be found on the Web at www.trforum.org. Disclaimer: The facts, opinions, and conclusions set forth in this article contained herein are those of the author(s) and quotations should be so attributed. They do not necessarily represent the views and opinions of the Transportation Research Forum (TRF), nor can TRF assume any responsibility for the accuracy or validity of any of the information contained herein.
1 AN ANALYTICAL REAL OPTION REPLACEMENT MODEL WITH DEPRECIATION
"... A replacement model is presented for a productive asset subject to stochastic input decay, tax allowances due to a deterministic depreciation variable, and a fixed investment cost. The risk neutral valuation function is formulated and optimal trigger levels signalling replacement for the two factors ..."
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A replacement model is presented for a productive asset subject to stochastic input decay, tax allowances due to a deterministic depreciation variable, and a fixed investment cost. The risk neutral valuation function is formulated and optimal trigger levels signalling replacement for the two factors is determined analytically although not as a closedform solution. We demonstrate that the operating cost trigger level depends on asset age and increases monotonically due to positive volatility changes and that the model solution furnishes the results for certain special cases. The analysis is conducted both for a depreciation schedule specified by the declining balance and straight line method. The comparative analysis shows that although no universal ideal depreciation schedule exists between the two, the declining balance method is preferred. Finally, the solution method is sufficiently tractable to be applied in principle to real option models where time is a critical factor. 1.
Assistant Teacher
"... In every field of our real life situations, we deal with a replacement problem, when some items such as machines, medical equipment, military tank, electric bulb etc. or workers need to replace due to their decreased efficiency, failure or break down. To get a more realistic view of a replacement pr ..."
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In every field of our real life situations, we deal with a replacement problem, when some items such as machines, medical equipment, military tank, electric bulb etc. or workers need to replace due to their decreased efficiency, failure or break down. To get a more realistic view of a replacement problem, here, we consider that the capital cost ( C ~), scrap value or resale) are all of value ( S ~), maintenance cost or running cost ( ft fuzzy numbers. These fuzzy numbers are considered as a trapezoidal fuzzy numbers or triangular fuzzy numbers. Yager’s Ranking method (1981) has been used to determine the best alternative of fuzzy numbers. It has been also used to transform a replacement model with fuzzy cost to a replacement model with crisp cost. Then we solved it by any conventional method. Two numerical examples have been solved to show the effectiveness of the proposed method.
Remanufacturable Product Design and Contracts under Extended Producer Responsibility
, 2005
"... Extended Producer Responsibility (EPR) legislation focuses on the lifecycle environmental performance of products. EPR has significant implications for management theory and practice. However, there is very little operations management research that examines the influence of EPR policy parameters ..."
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Extended Producer Responsibility (EPR) legislation focuses on the lifecycle environmental performance of products. EPR has significant implications for management theory and practice. However, there is very little operations management research that examines the influence of EPR policy parameters on product design, the interactions among these parameters, and strategic managerial responses to combinations of parameters that constitute EPR instruments. We analytically establish optimal product design and pricing decisions by a manufacturer producing and selling a remanufacturable, durable product, in response to various implementations of EPR. We model a single manufacturer supplying a remanufacturable product to a single customer over multiple periods. The customer has a continuing need for the services of the product and optimizes between the costs of product replacement and the costs of operating the product. We model two environmental design attributes of the product that impact costs to both the manufacturer as well as the customer a onedimensional “more is better” measure of environmental performance that captures the environmental impact of the product during use, and a measure of product remanufacturability that captures the environmental impact of the product postuse. From an environmental standpoint, we find that higher costs for environmental impacts
Maintenance and replacement policies for protective devices
"... with imperfect repairs ..."
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