WorldWideScience

Sample records for optimal replacement policies

  1. Optimal Overhaul-Replacement Policies for Repairable Machine Sold with Warranty

    Directory of Open Access Journals (Sweden)

    Kusmaningrum Soemadi

    2014-12-01

    Full Text Available This research deals with an overhaul-replacement policy for a repairable machine sold with Free Replacement Warranty (FRW. The machine will be used for a finite horizon, T (T <, and evaluated at a fixed interval, s (s< T. At each evaluation point, the buyer considers three alternative decisions i.e. Keep the machine, Overhaul it, or Replace it with a new identical one. An overhaul can reduce the machine age virtually, but not to a point that the machine is as good as new. If the machine fails during the warranty period, it is rectified at no cost to the buyer. Any failure occurring before and after the expiry of the warranty is restored by minimal repair. An overhaul-replacement policy is formulated for such machines by using dynamic programming approach to obtain the buyer’s optimal policy. The results show that a significant rejuvenation effect due to overhaul may extend the length of machine life cycle and delay the replacement decision. In contrast, the warranty stimulates early machine replacement and by then increases the replacement frequencies for a certain range of replacement cost. This demonstrates that to minimize the total ownership cost over T the buyer needs to consider the minimal repair cost reduction due to rejuvenation effect of overhaul as well as the warranty benefit due to replacement. Numerical examples are presented for both illustrating the optimal policy and describing the behavior of the optimal solution.

  2. Determining Optimal Replacement Policy with an Availability Constraint via Genetic Algorithms

    Directory of Open Access Journals (Sweden)

    Shengliang Zong

    2017-01-01

    Full Text Available We develop a model and a genetic algorithm for determining an optimal replacement policy for power equipment subject to Poisson shocks. If the time interval of two consecutive shocks is less than a threshold value, the failed equipment can be repaired. We assume that the operating time after repair is stochastically nonincreasing and the repair time is exponentially distributed with a geometric increasing mean. Our objective is to minimize the expected average cost under an availability requirement. Based on this average cost function, we propose the genetic algorithm to locate the optimal replacement policy N to minimize the average cost rate. The results show that the GA is effective and efficient in finding the optimal solutions. The availability of equipment has significance effect on the optimal replacement policy. Many practical systems fit the model developed in this paper.

  3. Building a Data-Driven Vital Sign Indicator for an Economically Optimized Component Replacement Policy

    Science.gov (United States)

    2014-10-02

    Jardine & Tsang, 2013). The optimization of replacement decision policy based on component failure predictions has been critical in the area of...PROGNOSTICS AND HEALTH MANAGEMENT SOCIETY 2014 2 (Banjevic, Jardine , Makis, & Ennis, 2001)( Jardine , Banjevic, Montgomery, & Pak, 2008). In practice, the...of the American Statistical Association, 101(473). Banjevic, D., Jardine , A., Makis, V., & Ennis, M. (2001). A control-limit policy and software for

  4. A bivariate optimal replacement policy with cumulative repair cost limit under cumulative damage model

    Indian Academy of Sciences (India)

    MIN-T SAI LAI; SHIH-CHIH CHEN

    2016-05-01

    In this paper, a bivariate replacement policy (n, T) for a cumulative shock damage process is presented that included the concept of cumulative repair cost limit. The arrival shocks can be divided into two kinds of shocks. Each type-I shock causes a random amount of damage and these damages are additive. When the total damage exceeds a failure level, the system goes into serious failure. Type-II shock causes the system into minor failure and such a failure can be corrected by minimal repair. When a minor failure occurs, the repaircost will be evaluated and minimal repair is executed if the accumulated repair cost is less than a predetermined limit L. The system is replaced at scheduled time T, at n-th minor failure, or at serious failure. The long-term expected cost per unit time is derived using the expected costs as the optimality criterion. The minimum-cost policy is derived, and existence and uniqueness of the optimal n* and T* are proved. This bivariate optimal replacement policy (n, T) is showed to be better than the optimal T* and the optimal n* policy.

  5. A Computationally Efficient P-LRU based Optimal Cache Heap Object Replacement Policy

    Directory of Open Access Journals (Sweden)

    Burhan Ul Islam Khan

    2017-01-01

    Full Text Available The recent advancement in the field of distributed computing depicts a need of developing highly associative and less expensive cache memories for the state-of-art processors i.e., Intel Core i6, i7, etc. Hence, various conventional studies introduced cache replacement policies which are one of the prominent key factors to determine the effectiveness of a cache memory. Most of the conventional cache replacement algorithms are found to be as not so efficient on memory management and complexity analysis. Therefore, a significant and thorough analysis is required to suggest a new optimal solution for optimizing the state-of-the-art cache replacement issues. The proposed study aims to conceptualize a theoretical model for optimal cache heap object replacement. The proposed model incorporates Tree based and MRU (Most Recently Used pseudo-LRU (Least Recently Used mechanism and configures it with JVM’s garbage collector to replace the old referenced objects from the heap cache lines. The performance analysis of the proposed system illustrates that it outperforms the conventional state of art replacement policies with much lower cost and complexity. It also depicts that the percentage of hits on cache heap is relatively higher than the conventional technologies.

  6. Optimal Replacement Policy of Jet Engine Modules from the Aircarrier's Point of View

    Directory of Open Access Journals (Sweden)

    Anita Domitrović

    2008-01-01

    Full Text Available A mathematical model for optimising preventive maintenanceof aircraft jet engine was developed by dynamic programming.Replacement planning for jet engine modules is regardedas a multistage decision process, while optimum modulereplacement is considered as a problem of equipment replacement.The goal of the optimal replacement policy of jet enginemodules is a defined series of decisions resulting in minimummaintenance costs. The model was programmed inC++ programming language and tested by using CFM56 jetengine data. The optimum maintenance strategy costs werecompared to costs of simpler experience-based maintenancestrategies. The results of the comparison j usti.JY further developmentand usage of the model in order to achieve significant costreduction for airline carriers.

  7. A Robust Bayesian Approach to an Optimal Replacement Policy for Gas Pipelines

    Directory of Open Access Journals (Sweden)

    José Pablo Arias-Nicolás

    2015-06-01

    Full Text Available In the paper, we address Bayesian sensitivity issues when integrating experts’ judgments with available historical data in a case study about strategies for the preventive maintenance of low-pressure cast iron pipelines in an urban gas distribution network. We are interested in replacement priorities, as determined by the failure rates of pipelines deployed under different conditions. We relax the assumptions, made in previous papers, about the prior distributions on the failure rates and study changes in replacement priorities under different choices of generalized moment-constrained classes of priors. We focus on the set of non-dominated actions, and among them, we propose the least sensitive action as the optimal choice to rank different classes of pipelines, providing a sound approach to the sensitivity problem. Moreover, we are also interested in determining which classes have a failure rate exceeding a given acceptable value, considered as the threshold determining no need for replacement. Graphical tools are introduced to help decisionmakers to determine if pipelines are to be replaced and the corresponding priorities.

  8. OPTIMUM ORDERING POLICY FOR PREVENTIVE AGE REPLACEMENT

    Institute of Scientific and Technical Information of China (English)

    Young T.PARK; Jing SUN

    2009-01-01

    Most of the spare ordering policies treated up to now have assumed that preventive and corrective replacement costs are equal, which implies in essential that there is no significant need for preventive replacement. This paper presents an ordering policy for preventive age replacement with minimal repair. Introducing the replacement, repair, inventory holding and shortage costs, the expected cost rate is derived. A procedure to determine jointly the ordering time for a spare and the preventive replacement time for the operating unit so as to minimize the expected cost rate is proposed. To explain the ordering policy and the optimization procedure, a numerical example is also included.

  9. A large Markovian linear program to optimize replacement policies and dairy herd net income for diets and nitrogen excretion.

    Science.gov (United States)

    Cabrera, V E

    2010-01-01

    The purpose of the study was 2-fold: 1) to propose a novel modeling framework using Markovian linear programming to optimize dairy farmer-defined goals under different decision schemes and 2) to illustrate the model with a practical application testing diets for entire lactations. A dairy herd population was represented by cow state variables defined by parity (1 to 15), month in lactation (1 to 24), and pregnancy status (0 nonpregnant and 1 to 9 mo of pregnancy). A database of 326,000 lactations of Holsteins from AgSource Dairy Herd Improvement service (http://agsource.crinet.com/page249/DHI) was used to parameterize reproduction, mortality, and involuntary culling. The problem was set up as a Markovian linear program model containing 5,580 decision variables and 8,731 constraints. The model optimized the net revenue of the steady state dairy herd population having 2 options in each state: keeping or replacing an animal. Five diets were studied to assess economic, environmental, and herd structural outcomes. Diets varied in proportions of alfalfa silage (38 to 98% of dry matter), high-moisture ear corn (0 to 42% of dry matter), and soybean meal (0 to 18% of dry matter) within and between lactations, which determined dry matter intake, milk production, and N excretion. Diet ingredient compositions ranged from one of high concentrates to alfalfa silage only. Hence, the model identified the maximum net revenue that included the value of nutrient excretion and the cost of manure disposal associated with the optimal policy. Outcomes related to optimal solutions included the herd population structure, the replacement policy, and the amount of N excreted under each diet experiment. The problem was solved using the Excel Risk Solver Platform with the Standard LP/Quadratic Engine. Consistent replacement policies were to (1) keep pregnant cows, (2) keep primiparous cows longer than multiparous cows, and (3) decrease replacement rates when milk and feed prices are favorable

  10. Optimal replacement policies for dairy cows based on daily yield measurements

    DEFF Research Database (Denmark)

    Nielsen, Lars Relund; Jørgensen, Erik; Kristensen, Anders Ringgaard;

    2010-01-01

    describes the first step of developing an MDP model that can be integrated into a modern herd management system. A hierarchical MDP was formulated for the dairy cow replacement problem with stage lengths of 1 d. It can be used to assist the farmer in replacement decisions on a daily basis and is based...... on daily milk yield measurements that are available in modern milking systems. Bayesian updating was used to predict the performance of each cow in the herd and economic decisions were based on the prediction. Moreover, parameters in the model were estimated using data records of the specific herd under...

  11. Optimal Repair And Replacement Policy For A System With Multiple Components

    Science.gov (United States)

    2016-06-17

    probabilistic life-cycle maintenance mod- els for deteriorating civil infrastructure. Probabilistic Enginering Mechanics 19 345– 359. Zhang, Y.L. 2002. A...Repair, Replace, Multiple Component Models, Maintenance Models, Markov Decision Process 15. NUMBER OF PAGES 83 16. PRICE CODE 17. SECURITY...Parametric Analysis of the Fuel System . . . . . . . . . . . . . . 39 6 Conclusions and Future Work 45 6.1 Conclusions

  12. Interactions between optimal replacement policies and feeding strategies in dairy herds

    NARCIS (Netherlands)

    Vargas, B.; Herrero, M.; Arendonk, van J.A.M.

    2001-01-01

    A dynamic performance model was integrated with a model that optimised culling and insemination policies in dairy herds using dynamic programming. The performance model estimated daily feed intake, milk yield and body weight change of dairy cows on the basis of availability and quality of feed and p

  13. 管制消费的最优替代政策%Optimal Replacement Policy of Regulation Consumption

    Institute of Scientific and Technical Information of China (English)

    李贺明; 张勤; 李进伟

    2013-01-01

    Since reform and opening up, China has let go of the controls in the areas of the economy, and the vitality of market is constantly enhancing. Socialist development mode with Chinese characteristics is emerging as a growth engine of the global economy. But in recent years, as the economic growth and more and more serious resource environment contradictions, Government carried out more and more restrictions on the micro-economic consumer behavior and abuse. This article starts from the perspective of improving public services, and proposes theoretical basis for transforming government functions and creating a service-oriented government and the optimal replacement policy of regulation consumption.%改革开放以来,我国在经济领域不断放开管制,市场主体活力不断增强,有中国特色的社会主义发展模式逐步成为全球经济的增长引擎之一。但近年来,随着经济增长和资源环境的矛盾越来越突出,政府对微观经济体的消费行为限制及弊端也越来越多。本文从改进政府公共服务的角度出发,提出转变政府职能、创建服务型政府的理论依据和管制消费的替代政策。

  14. Inspection-replacement policy of system under predictive maintenance

    Institute of Scientific and Technical Information of China (English)

    LIU Bao-you; FANG You-tong; WEI Jin-xiang; WANG Yong-liang

    2007-01-01

    In general, every system is in one of the three states: normal, abnormal, or failure state. When the system is diagnosed as abnormal state, it needs predictive maintenance. If the system fails, an identical new one will replace it. The predictive maintenance cannot make the system "as good as new". Under these assumptions, the reliability index and the inspection-replacement policy of a system were studied. The explicit expression of the reliability index and the average income rate (i.e., the long-runaverage income per unit time) are derived by using probability analysis and vector Markov process method. The criterion of feasibility for the optimal inspection-replacement policy under the maximum average income rate is obtained. The numerical example shows the optimal inspection-replacement policy can raise the average income rate when the optimal inspection-replacement policy is feasible.

  15. Optimal randomized scheduling by replacement

    Energy Technology Data Exchange (ETDEWEB)

    Saias, I.

    1996-05-01

    In the replacement scheduling problem, a system is composed of n processors drawn from a pool of p. The processors can become faulty while in operation and faulty processors never recover. A report is issued whenever a fault occurs. This report states only the existence of a fault but does not indicate its location. Based on this report, the scheduler can reconfigure the system and choose another set of n processors. The system operates satisfactorily as long as, upon report of a fault, the scheduler chooses n non-faulty processors. We provide a randomized protocol maximizing the expected number of faults the system can sustain before the occurrence of a crash. The optimality of the protocol is established by considering a closely related dual optimization problem. The game-theoretic technical difficulties that we solve in this paper are very general and encountered whenever proving the optimality of a randomized algorithm in parallel and distributed computation.

  16. Replacement policies for dairy cows

    DEFF Research Database (Denmark)

    Nielsen, Lars Relund

    In a recent paper a hierarchical Markov decision processes (MDP) with finite state and action space was formulated for the dairy cow replacement problem with stage lengths of 1 d. Bayesian updating was used to predict the performance of each cow in the herd and economic decisions were based...

  17. Optimizing model. 1. Insemination, replacement, seasonal production and cash flow.

    NARCIS (Netherlands)

    Delorenzo, M.A.; Spreen, T.H.; Bryan, G.R.; Beede, D.K.; Arendonk, van J.A.M.

    1992-01-01

    Dynamic programming to solve the Markov decision process problem of optimal insemination and replacement decisions was adapted to address large dairy herd management decision problems in the US. Expected net present values of cow states (151,200) were used to determine the optimal policy. States

  18. Optimizing model. 1. Insemination, replacement, seasonal production and cash flow.

    NARCIS (Netherlands)

    Delorenzo, M.A.; Spreen, T.H.; Bryan, G.R.; Beede, D.K.; Arendonk, van J.A.M.

    1992-01-01

    Dynamic programming to solve the Markov decision process problem of optimal insemination and replacement decisions was adapted to address large dairy herd management decision problems in the US. Expected net present values of cow states (151,200) were used to determine the optimal policy. States wer

  19. PERFORMANCE OF PRIVATE CACHE REPLACEMENT POLICIES FOR MULTICORE PROCESSORS

    Directory of Open Access Journals (Sweden)

    Matthew Lentz

    2014-07-01

    Full Text Available Multicore processors have become ubiquitous, both in general-purpose and special-purpose applications. With the number of transistors in a chip continuing to increase, the number of cores in a processor is also expected to increase. Cache replacement policy is an important design parameter of a cache hierarchy. As most of the processor designs have become multicore, there is a need to study cache replacement policies for multi-core systems. Previous studies have focused on the shared levels of the multicore cache hierarchy. In this study, we focus on the top level of the hierarchy, which bears the brunt of the memory requests emanating from each processor core. We measure the miss rates of various cache replacement policies, as the number of cores is steadily increased from 1 to 16. The study was done by modifying the publicly available SESC simulator, which models in detail a multicore processor with a multilevel cache hierarchy. Our experimental results show that for the private L1 caches, the LRU (Least Recently Used replacement policy outperforms all of the other replacement policies. This is in contrast to what was observed in previous studies for the shared L2 cache. The results presented in this paper are useful for hardware designers to optimize their cache designs or the program codes.

  20. OPTIMAL MAINTENANCE AND REPLACEMENT OF EXTRACTION MACHINERY

    Institute of Scientific and Technical Information of China (English)

    Suresh P.SETHI; Hong-Mo YEH; Rong ZHANG; Andrew K.S.JARDINE

    2008-01-01

    This paper considers a problem of optimal preventive maintenance and replacement schedule ofequipment devoted to extracting resources from known deposits. Typical examples are oil drills, mine shovels, etc. At most one replacement of the existing machinery by a new one is allowed. The problem is formulated as an optimal control problem subject to the state constraint that the remaining deposit at any given time is nonnegative. We show that the optimal preventive maintenance, production rates, and the replacement and salvage times of the existing machinery and the new one, if required, can be obtained by solving sequentially a series of free-end-point optimal control problems. Moreover, an algorithm based on this result is developed and used to solve two illustrative examples.

  1. Optimal patent policies: A survey

    DEFF Research Database (Denmark)

    Poulsen, Odile

    2002-01-01

    , the government uses two policy tools, the optimal breadth and length. We show that theoretical models give very different answers to what is the optimal patent policy. In particular, we show that the optimal patent policy depends among othet things on the price elasticity of demand, the intersectoral elasticity...

  2. Optimal patent policies: A survey

    DEFF Research Database (Denmark)

    Poulsen, Odile

    2002-01-01

    This paper surveys some of the patent literature, in particular, it focuses on optimal patent policies. We compare two situations. The first where the government only has a single policy tool to design the optimal patent policy, namely the optimal patent length. In the second situation, the gover......This paper surveys some of the patent literature, in particular, it focuses on optimal patent policies. We compare two situations. The first where the government only has a single policy tool to design the optimal patent policy, namely the optimal patent length. In the second situation...... of research outputs as well as the degree of compettition in the R&D sector. The actual law on intellectual property, which advocates a unique patent length of 20 years is in general not supported by theoretical models....

  3. Dynamic optimization of maintenance and improvement planning for water main system: Periodic replacement approach

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Woo; Choi, Go Bong; Lee, Jong Min [Seoul National University, Seoul (Korea, Republic of); Suh, Jung Chul [Samchully Corporation, Seoul (Korea, Republic of)

    2016-01-15

    This paper proposes a Markov decision process (MDP) based approach to derive an optimal schedule of maintenance, rehabilitation and replacement of the water main system. The scheduling problem utilizes auxiliary information of a pipe such as the current state, cost, and deterioration model. The objective function and detailed algorithm of dynamic programming are modified to solve the periodic replacement problem. The optimal policy evaluated by the proposed algorithm is compared to several existing policies via Monte Carlo simulations. The proposed decision framework provides a systematic way to obtain an optimal policy.

  4. Three optimizing models for Web cache replacement policies%三种Web缓存替换的最优化模型研究

    Institute of Scientific and Technical Information of China (English)

    韩英杰; 胡静

    2011-01-01

    By analyzing the major factors which affect the cache performance, such as object size, frequency , and access delay, by choosing cost factor, three optimized models are obtained: maximization of hit rate, maximization of byte hit rate and minimization of delay. The analytical result showed that the optimizing '' models are right. In practical application, the optimized models have flexibility and feasibility.%根据影响Web缓存性能的文件大小、访问频度、延迟等因素,通过灵活地选择代价因子,得到了命中率最大化、字节命中率最大化和延迟最小化3种Web缓存替换的最优化模型.模拟实验验证了该模型的正确性、灵活性和适用性.

  5. Determining the optimum replacement policy for Holstein dairy herds in Iran.

    Science.gov (United States)

    Kalantari, A S; Mehrabani-Yeganeh, H; Moradi, M; Sanders, A H; De Vries, A

    2010-05-01

    The objective of this study was to determine the optimum replacement policy for Holstein dairy herds in Iran using a dynamic programming model. Cows were described in terms of state variables that included milk production class, parity, pregnancy status, and month in milk with a 1-mo stage length. The objective function maximized the net present value of cows over a 15-yr planning horizon. Markov simulation was used to estimate expected herd dynamics under the optimal decision plan determined by dynamic programming. Stochastic elements included probabilities of pregnancy and abortion, production level, and involuntary culling. The optimum annual culling rate was estimated to be 31.4%, and cows had an expected herd life (time from first calving until culling) of 3.18 yr. High replacement cost and low carcass value resulted in only 2.87% voluntary culling (i.e., optimal model-based replacement). Assuming a heat detection rate of 0.4, cows averaged 2.8 services per lactation under the optimal policy. Sensitivity analyses were carried out to evaluate the effect of milk price, herd-average production, feed cost, heifer price, and carcass value on optimum replacement decisions. Herd-average production, replacement cost, and risk of involuntary culling were important factors affecting the optimal culling policy. Changes in the price of feed, calves, and milk and the probability of pregnancy had no considerable effect on the optimal policy considering the market situation in Iran during 2008.

  6. Life cycle optimization of automobile replacement: model and application.

    Science.gov (United States)

    Kim, Hyung Chul; Keoleian, Gregory A; Grande, Darby E; Bean, James C

    2003-12-01

    Although recent progress in automotive technology has reduced exhaust emissions per mile for new cars, the continuing use of inefficient, higher-polluting old cars as well as increasing vehicle miles driven are undermining the benefits of this progress. As a way to address the "inefficient old vehicle" contribution to this problem, a novel life cycle optimization (LCO) model is introduced and applied to the automobile replacement policy question. The LCO model determines optimal vehicle lifetimes, accounting for technology improvements of new models while considering deteriorating efficiencies of existing models. Life cycle inventories for different vehicle models that represent materials production, manufacturing, use, maintenance, and end-of-life environmental burdens are required as inputs to the LCO model. As a demonstration, the LCO model was applied to mid-sized passenger car models between 1985 and 2020. An optimization was conducted to minimize cumulative carbon monoxide (CO), non-methane hydrocarbon (NMHC), oxides of nitrogen (NOx), carbon dioxide (CO2), and energy use over the time horizon (1985-2020). For CO, NMHC, and NOx pollutants with 12000 mi of annual mileage, automobile lifetimes ranging from 3 to 6 yr are optimal for the 1980s and early 1990s model years while the optimal lifetimes are expected to be 7-14 yr for model year 2000s and beyond. On the other hand, a lifetime of 18 yr minimizes cumulative energy and CO2 based on driving 12000 miles annually. Optimal lifetimes are inversely correlated to annual vehicle mileage, especially for CO, NMHC, and NOx emissions. On the basis of the optimization results, policies improving durability of emission controls, retiring high-emitting vehicles, and improving fuel economies are discussed.

  7. A general approach to total repair cost limit replacement policies

    Directory of Open Access Journals (Sweden)

    F. Beichelt

    2014-01-01

    Full Text Available A common replacement policy for technical systems consists in replacing a system by a new one after its economic lifetime, i.e. at that moment when its long-run maintenance cost rate is minimal. However, the strict application of the economic lifetime does not take into account the individual deviations of maintenance cost rates of single systems from the average cost development. Hence, Beichet proposed the total repair cost limit replacement policy: the system is replaced by a new one as soon as its total repair cost reaches or exceeds a given level. He modelled the repair cost development by functions of the Wiener process with drift. Here the same policy is considered under the assumption that the one-dimensional probability distribution of the process describing the repair cost development is given. In the examples analysed, applying the total repair cost limit replacement policy instead of the economic life-time leads to cost savings of between 4% and 30%. Finally, it is illustrated how to include the reliability aspect into the policy.

  8. Process optimized minimally invasive total hip replacement

    Directory of Open Access Journals (Sweden)

    Philipp Gebel

    2012-02-01

    Full Text Available The purpose of this study was to analyse a new concept of using the the minimally invasive direct anterior approach (DAA in total hip replacement (THR in combination with the leg positioner (Rotex- Table and a modified retractor system (Condor. We evaluated retrospectively the first 100 primary THR operated with the new concept between 2009 and 2010, regarding operation data, radiological and clinical outcome (HOOS. All surgeries were perfomed in a standardized operation technique including navigation. The average age of the patients was 68 years (37 to 92 years, with a mean BMI of 26.5 (17 to 43. The mean time of surgery was 80 min. (55 to 130 min. The blood loss showed an average of 511.5 mL (200 to 1000 mL. No intra-operative complications occurred. The postoperative complication rate was 6%. The HOOS increased from 43 points pre-operatively to 90 (max 100 points 3 months after surgery. The radiological analysis showed an average cup inclination of 43° and a leg length discrepancy in a range of +/- 5 mm in 99%. The presented technique led to excellent clinic results, showed low complication rates and allowed correct implant positions although manpower was saved.

  9. Optimization criteria for the design of orbital replacement units (ORUs)

    Science.gov (United States)

    Schulze, Manfred W.

    A reduction of life cycle costs of spacecraft or Space Station elements can be achieved by a modular build up which allows an in orbit replacement, maintenance, and service of functional units named Orbital Replacement Units (ORUs). The criteria for an optimal design for an ORU is presented. Requirements involving the user spacecraft configuration, the servicing vehicle, the handling by astronauts and remote manipulator system are considered.

  10. Optimal replacement of residential air conditioning equipment to minimize energy, greenhouse gas emissions, and consumer cost in the US

    Energy Technology Data Exchange (ETDEWEB)

    De Kleine, Robert D. [Center for Sustainable Systems, School of Natural Resources and Environment, University of Michigan, 440 Church St., Dana Bldg., Ann Arbor, MI 48109-1041 (United States); Keoleian, Gregory A., E-mail: gregak@umich.edu [Center for Sustainable Systems, School of Natural Resources and Environment, University of Michigan, 440 Church St., Dana Bldg., Ann Arbor, MI 48109-1041 (United States); Kelly, Jarod C. [Center for Sustainable Systems, School of Natural Resources and Environment, University of Michigan, 440 Church St., Dana Bldg., Ann Arbor, MI 48109-1041 (United States)

    2011-06-15

    A life cycle optimization of the replacement of residential central air conditioners (CACs) was conducted in order to identify replacement schedules that minimized three separate objectives: life cycle energy consumption, greenhouse gas (GHG) emissions, and consumer cost. The analysis was conducted for the time period of 1985-2025 for Ann Arbor, MI and San Antonio, TX. Using annual sales-weighted efficiencies of residential CAC equipment, the tradeoff between potential operational savings and the burdens of producing new, more efficient equipment was evaluated. The optimal replacement schedule for each objective was identified for each location and service scenario. In general, minimizing energy consumption required frequent replacement (4-12 replacements), minimizing GHG required fewer replacements (2-5 replacements), and minimizing cost required the fewest replacements (1-3 replacements) over the time horizon. Scenario analysis of different federal efficiency standards, regional standards, and Energy Star purchases were conducted to quantify each policy's impact. For example, a 16 SEER regional standard in Texas was shown to either reduce primary energy consumption 13%, GHGs emissions by 11%, or cost by 6-7% when performing optimal replacement of CACs from 2005 or before. The results also indicate that proper servicing should be a higher priority than optimal replacement to minimize environmental burdens. - Highlights: > Optimal replacement schedules for residential central air conditioners were found. > Minimizing energy required more frequent replacement than minimizing consumer cost. > Significant variation in optimal replacement was observed for Michigan and Texas. > Rebates for altering replacement patterns are not cost effective for GHG abatement. > Maintenance levels were significant in determining the energy and GHG impacts.

  11. Optimal Inventory Policies When Sales Are Discretionary

    OpenAIRE

    Herbert E. Scarf

    2000-01-01

    Inventory models customarily assume that demand is fully satisfied if sufficient stock is available. We analyze the form of the optimal inventory policy if the inventory manager can choose to meet a fraction of the demand. Under classical conditions we show that the optimal policy is again of the (S,s) form. The analysis makes use of a novel property of K-concave functions.

  12. Optimal Inventory Policies When Sales Are Discretionary

    OpenAIRE

    Scarf, Herbert E.

    2000-01-01

    Inventory models customarily assume that demand is fully satisfied if sufficient stock is available. We analyze the form of the optimal inventory policy if the inventory manager can choose to meet a fraction of the demand. Under classical conditions we show that the optimal policy is again of the (S,s) form. The analysis makes use of a novel property of K-concave functions.

  13. Optimal Bank Regulation and Monetary Policy

    OpenAIRE

    John J. Seater

    2000-01-01

    A unified model of monetary policy and bank regulation is presented. In accordance with modern banking theory, banks not only intermediate loans and deposits but also provide a financial service affecting aggregate output. Optimal parameter settings for monetary and regulatory policy are derived. New results are that monetary policy affects the expected level as well as the variance of output, bank regulation should change continually in response to the state of the economy, and bank regulati...

  14. Pricing and inventory policies for Hi-tech products under replacement warranty

    Science.gov (United States)

    Tsao, Yu-Chung; Teng, Wei-Guang; Chen, Ruey-Shii; Chou, Wang-Ying

    2014-06-01

    Companies, especially in the Hi-tech (high-technology) industry (such as computer, communication and consumer electronic products), often provide a replacement warranty period for purchased items. In reality, simultaneously determining the price and inventory decisions under warranty policy is an important issue. The objective of this paper is to develop a joint pricing and inventory model for Hi-tech products under replacement warranty policy. In the first model, we consider a Hi-tech product feature in which the selling price is declining in a trend. We determine the optimal inventory level for each period and retail price for the first period while maximising the total profit. In the second model, we further determine the optimal retail price and inventory level for each period in the dynamic demand market. This study develops solution approaches to solve the problems described above. Numerical analysis discusses the influence of system parameters on the company's decisions and behaviours. The results of this study could serve as a reference for business managers or administrators.

  15. Optimal Selective Feedback Policies for Opportunistic Beamforming

    CERN Document Server

    Samarasinghe, Tharaka; Evans, Jamie S

    2011-01-01

    This paper studies the structure of downlink sum-rate maximizing selective decentralized feedback policies for opportunistic beamforming under finite feedback constraints on the average number of mobile users feeding back. Firstly, it is shown that any sum-rate maximizing selective decentralized feedback policy must be a threshold feedback policy. This result holds for all fading channel models with continuous distribution functions. Secondly, the resulting optimum threshold selection problem is analyzed in detail. This is a non-convex optimization problem over finite dimensional Euclidean spaces. By utilizing the theory of majorization, an underlying Schur-concave structure in the sum-rate function is identified, and the sufficient conditions for the optimality of homogenous threshold feedback policies are obtained. Applications of these results are illustrated for well known fading channel models such as Rayleigh, Nakagami and Rician fading channels, along with various engineering and design insights. Rathe...

  16. Studies on the replacement policies in dairy cattle

    NARCIS (Netherlands)

    Arendonk, van J.A.M.

    1985-01-01

    In The Netherlands dairy farmers replace on average 25-30% of their cows each year. The decision to replace instead of to keep a cow is based mainly on economic considerations rather than because a cow is no longer able to produce.

    The investigations described in this thesis were

  17. The Study of Cost Rate for Multiple Cold Standby System Replacement Policies

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    We consider a replacement policy for a multiple-component cold-standby system, and after we analyze this policy, we want to get the mean total cost rate and the preventive policy to make it the lowest. In this system, the failure rate of the component in operation is constant, and the inspection will control all the processes of the operation. The system is inspected at random points over time to determine whether it is to be replaced. During the process, the replacement decision is based on the number of failed components at the time of inspection.

  18. Chaotic dynamics in optimal monetary policy

    Science.gov (United States)

    Gomes, O.; Mendes, V. M.; Mendes, D. A.; Sousa Ramos, J.

    2007-05-01

    There is by now a large consensus in modern monetary policy. This consensus has been built upon a dynamic general equilibrium model of optimal monetary policy as developed by, e.g., Goodfriend and King [ NBER Macroeconomics Annual 1997 edited by B. Bernanke and J. Rotemberg (Cambridge, Mass.: MIT Press, 1997), pp. 231 282], Clarida et al. [J. Econ. Lit. 37, 1661 (1999)], Svensson [J. Mon. Econ. 43, 607 (1999)] and Woodford [ Interest and Prices: Foundations of a Theory of Monetary Policy (Princeton, New Jersey, Princeton University Press, 2003)]. In this paper we extend the standard optimal monetary policy model by introducing nonlinearity into the Phillips curve. Under the specific form of nonlinearity proposed in our paper (which allows for convexity and concavity and secures closed form solutions), we show that the introduction of a nonlinear Phillips curve into the structure of the standard model in a discrete time and deterministic framework produces radical changes to the major conclusions regarding stability and the efficiency of monetary policy. We emphasize the following main results: (i) instead of a unique fixed point we end up with multiple equilibria; (ii) instead of saddle-path stability, for different sets of parameter values we may have saddle stability, totally unstable equilibria and chaotic attractors; (iii) for certain degrees of convexity and/or concavity of the Phillips curve, where endogenous fluctuations arise, one is able to encounter various results that seem intuitively correct. Firstly, when the Central Bank pays attention essentially to inflation targeting, the inflation rate has a lower mean and is less volatile; secondly, when the degree of price stickiness is high, the inflation rate displays a larger mean and higher volatility (but this is sensitive to the values given to the parameters of the model); and thirdly, the higher the target value of the output gap chosen by the Central Bank, the higher is the inflation rate and its

  19. Optimal monetary policy and oil price shocks

    Science.gov (United States)

    Kormilitsina, Anna

    This dissertation is comprised of two chapters. In the first chapter, I investigate the role of systematic U.S. monetary policy in the presence of oil price shocks. The second chapter is devoted to studying different approaches to modeling energy demand. In an influential paper, Bernanke, Gertler, and Watson (1997) and (2004) argue that systematic monetary policy exacerbated the recessions the U.S. economy experienced in the aftermath of post World War II oil price shocks. In the first chapter of this dissertation, I critically evaluate this claim in the context of an estimated medium-scale model of the U.S. business cycle. Specifically, I solve for the Ramsey optimal monetary policy in the medium-scale dynamic stochastic general equilibrium model (henceforth DSGE) of Schmitt-Grohe and Uribe (2005). To model the demand for oil, I use the approach of Finn (2000). According to this approach, the utilization of capital services requires oil usage. In the related literature on the macroeconomic effects of oil price shocks, it is common to calibrate structural parameters of the model. In contrast to this literature, I estimate the parameters of my DSGE model. The estimation strategy involves matching the impulse responses from the theoretical model to responses predicted by an empirical model. For estimation, I use the alternative to the classical Laplace type estimator proposed by Chernozhukov and Hong (2003). To obtain the empirical impulse responses, I identify an oil price shock in a structural VAR (SVAR) model of the U.S. business cycle. The SVAR model predicts that, in response to an oil price increase, GDP, investment, hours, capital utilization, and the real wage fall, while the nominal interest rate and inflation rise. These findings are economically intuitive and in line with the existing empirical evidence. Comparing the actual and the Ramsey optimal monetary policy response to an oil price shock, I find that the optimal policy allows for more inflation, a

  20. The Impact of Assessment Policy on Learning: Replacement Exams or Grade Dropping

    Science.gov (United States)

    MacDermott, Raymond J.

    2013-01-01

    Instructors often debate the merits of alternate grading policies such as dropping the lowest exam or offering an additional exam to replace the lowest score. To date, there has been little research conducted on the impact of these policies on performance. In this study, the author investigates student performance in intermediate macroeconomics…

  1. The Impact of Assessment Policy on Learning: Replacement Exams or Grade Dropping

    Science.gov (United States)

    MacDermott, Raymond J.

    2013-01-01

    Instructors often debate the merits of alternate grading policies such as dropping the lowest exam or offering an additional exam to replace the lowest score. To date, there has been little research conducted on the impact of these policies on performance. In this study, the author investigates student performance in intermediate macroeconomics…

  2. Experimental Results on Statistical Approaches to Page Replacement Policies

    Energy Technology Data Exchange (ETDEWEB)

    LEUNG,VITUS J.; IRANI,SANDY

    2000-12-08

    This paper investigates the questions of what statistical information about a memory request sequence is useful to have in making page replacement decisions: Our starting point is the Markov Request Model for page request sequences. Although the utility of modeling page request sequences by the Markov model has been recently put into doubt, we find that two previously suggested algorithms (Maximum Hitting Time and Dominating Distribution) which are based on the Markov model work well on the trace data used in this study. Interestingly, both of these algorithms perform equally well despite the fact that the theoretical results for these two algorithms differ dramatically. We then develop succinct characteristics of memory access patterns in an attempt to approximate the simpler of the two algorithms. Finally, we investigate how to collect these characteristics in an online manner in order to have a purely online algorithm.

  3. Optimal inventory policy within hospital space constraints.

    Science.gov (United States)

    Little, James; Coughlan, Brian

    2008-06-01

    The materials management group at any hospital is responsible for ensuring that their inventory policies provide a good service in delivering products. The group also needs to be aware of their own costs for distribution, in terms of the frequency of delivery. With future changes to the hospital's infrastructure, function and size, the group require that these policies are reviewed and prepared for the changes taking place. For this, inventory policy models need to be built and used to anticipate the effect of these changes. Due to the importance of many products, high service levels are essential, yet there are often space and delivery constraints, limiting the amount of stock which can be held and delivered at each location. We present in this paper a new constraint-based model for determining optimal stock levels for all products at a storage location, with restrictions on space, delivery and criticality of items taken into account. We validate this model on sterile and bulk items in a real-life setting of an intensive care unit within Cork University Hospital, Ireland.

  4. Optimal monetary policy in a model with agency costs

    OpenAIRE

    Timothy Fuerst; Matthias Paustian; Charles Carlstorm

    2009-01-01

    is the optimal policy. We derive the targeting criterion that implements optimal monetary policy under commitment and show under what conditions the target depends on leads or lags of the risk premium. Finally, the paper demonstrates that the degree of price stickiness and/or the nature of monetary policy alter the endogenous propagation of net worth across time.

  5. Optimal replacement time estimation for machines and equipment based on cost function

    Directory of Open Access Journals (Sweden)

    J. Šebo

    2013-01-01

    Full Text Available The article deals with a multidisciplinary issue of estimating the optimal replacement time for the machines. Considered categories of machines, for which the optimization method is usable, are of the metallurgical and engineering production. Different models of cost function are considered (both with one and two variables. Parameters of the models were calculated through the least squares method. Models testing show that all are good enough, so for estimation of optimal replacement time is sufficient to use simpler models. In addition to the testing of models we developed the method (tested on selected simple model which enable us in actual real time (with limited data set to indicate the optimal replacement time. The indicated time moment is close enough to the optimal replacement time t*.

  6. Optimal Differentiation Pricing Policy with Linear Demand Function

    Institute of Scientific and Technical Information of China (English)

    唐小我; 张明善

    2003-01-01

    The main objective in any marketing effort is to consider the optimal conditions to maximize revenue and profit. The optimal market segmentation pricing strategy is investigated under the assumption of an aggregate linear demand function. The optimal conditions to maximize revenue and profit, two closely correlative problems, are obtained respectively. The differentiation pricing policy described here can be easily applied in practice. A numerical example is provided which vividly illustrates the advantage of applying optimal policies.

  7. US fiscal regimes and optimal monetary policy

    NARCIS (Netherlands)

    Mavromatis, K.

    2014-01-01

    Fiscal policy in the US has been documented to have been the leading authority in the ‘60s and the ‘70s (active fiscal policy), while committing to make the necessary fiscal adjustments following Volcker’s appointment (passive fiscal policy). Moreover, while passive, US fiscal policy has at times

  8. Replacement

    Directory of Open Access Journals (Sweden)

    S. Radhakrishnan

    2014-03-01

    Full Text Available The fishmeal replaced with Spirulina platensis, Chlorella vulgaris and Azolla pinnata and the formulated diet fed to Macrobrachium rosenbergii postlarvae to assess the enhancement ability of non-enzymatic antioxidants (vitamin C and E, enzymatic antioxidants (superoxide dismutase (SOD and catalase (CAT and lipid peroxidation (LPx were analysed. In the present study, the S. platensis, C. vulgaris and A. pinnata inclusion diet fed groups had significant (P < 0.05 improvement in the levels of vitamins C and E in the hepatopancreas and muscle tissue. Among all the diets, the replacement materials in 50% incorporated feed fed groups showed better performance when compared with the control group in non-enzymatic antioxidant activity. The 50% fishmeal replacement (best performance diet fed groups taken for enzymatic antioxidant study, in SOD, CAT and LPx showed no significant increases when compared with the control group. Hence, the present results revealed that the formulated feed enhanced the vitamins C and E, the result of decreased level of enzymatic antioxidants (SOD, CAT and LPx revealed that these feeds are non-toxic and do not produce any stress to postlarvae. These ingredients can be used as an alternative protein source for sustainable Macrobrachium culture.

  9. Condition-based inspection/replacement policies for non-monotone deteriorating systems with environmental covariates

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Xuejing [Universite de Technologie de Troyes, Institut Charles Delaunay and STMR UMR CNRS 6279, 12 rue Marie Curie, 10010 Troyes (France); School of mathematics and statistics, Lanzhou University, Lanzhou 730000 (China); Fouladirad, Mitra, E-mail: mitra.fouladirad@utt.f [Universite de Technologie de Troyes, Institut Charles Delaunay and STMR UMR CNRS 6279, 12 rue Marie Curie, 10010 Troyes (France); Berenguer, Christophe [Universite de Technologie de Troyes, Institut Charles Delaunay and STMR UMR CNRS 6279, 12 rue Marie Curie, 10010 Troyes (France); Bordes, Laurent [Universite de Pau et des Pays de l' Adour, LMA UMR CNRS 5142, 64013 PAU Cedex (France)

    2010-08-15

    The aim of this paper is to discuss the problem of modelling and optimising condition-based maintenance policies for a deteriorating system in presence of covariates. The deterioration is modelled by a non-monotone stochastic process. The covariates process is assumed to be a time-homogenous Markov chain with finite state space. A model similar to the proportional hazards model is used to show the influence of covariates on the deterioration. In the framework of the system under consideration, an appropriate inspection/replacement policy which minimises the expected average maintenance cost is derived. The average cost under different conditions of covariates and different maintenance policies is analysed through simulation experiments to compare the policies performances.

  10. Optimal Policy under Restricted Government Spending

    DEFF Research Database (Denmark)

    Sørensen, Anders

    2006-01-01

    Welfare ranking of policy instruments is addressed in a two-sector Ramsey model with monopoly pricing in one sector as the only distortion. When government spending is restricted, i.e. when a government is unable or unwilling to finance the required costs for implementing the optimum policy...

  11. Achieving an Optimal Childhood Vaccine Policy.

    Science.gov (United States)

    Opel, Douglas J; Schwartz, Jason L; Omer, Saad B; Silverman, Ross; Duchin, Jeff; Kodish, Eric; Diekema, Douglas S; Marcuse, Edgar K; Orenstein, Walt

    2017-07-03

    Policies to remove parents' ability to opt-out from school immunization requirements on the basis of religious or personal beliefs (ie, nonmedical exemptions) may be a useful strategy to increase immunization rates and prevent outbreaks of vaccine-preventable disease. However, there is uncertainty about the effectiveness of this strategy and the range of possible outcomes. We advocate for a more deliberative process through which a broad range of outcomes is scrutinized and the balance of values underlying the policy decision to eliminate nonmedical exemptions is clearly articulated. We identify 3 outcomes that require particular consideration before policies to eliminate nonmedical exemptions are implemented widely and outline a process for making the values underlying such policies more explicit.

  12. AN OPTIMAL INVESTMENT AND INVENTORY POLICY

    NARCIS (Netherlands)

    VANDEWATER, H; VANDERVAART, T

    1991-01-01

    The relation between the optimal production level and the optimal investment in a flexible manufacturing machine will be the subject of this paper. The study concerns the production of N families of products on one production machine. The investment level in a particular production machine is assume

  13. Optimal Competition : A Benchmark for Competition Policy

    NARCIS (Netherlands)

    Boone, J.

    2003-01-01

    This paper introduces optimal competition: the best form of competition in an industry that a competition authority can achieve under the information constraint that it cannot observe firms' effciency levels.We show that the optimal competition outcome in an industry becomes more competitive as more

  14. AN OPTIMAL INVESTMENT AND INVENTORY POLICY

    NARCIS (Netherlands)

    VANDEWATER, H; VANDERVAART, T

    1991-01-01

    The relation between the optimal production level and the optimal investment in a flexible manufacturing machine will be the subject of this paper. The study concerns the production of N families of products on one production machine. The investment level in a particular production machine is

  15. Cost Optimal Reliability Based Inspection and Replacement Planning of Piping Subjected to CO2 Corrosion

    DEFF Research Database (Denmark)

    Hellevik, S. G.; Langen, I.; Sørensen, John Dalsgaard

    1999-01-01

    A methodology for cost optimal reliability based inspection and replacement planning of piping subjected to CO2 corrosion is described. Both initial (design phase) and in-service planning are dealt with. The methodology is based on the application of methods for structural reliability analysis...... within the framework of Bayesian decision theory. The planning problem is formulated as an optimization problem where the expected lifetime costs are minimized with a constraint on the minimum acceptable reliability level. The optimization parameters are the number of inspections in the expected lifetime......, the inspection times and methods. In the design phase the nominal design wall thickness is also treated as an optimization parameter. The most important benefits gained through the application of the methodology are consistent evaluation of the consequences of different inspection and replacement plans...

  16. Optimal drug use and rational drug policy.

    Science.gov (United States)

    Miller, Geoffrey F

    2011-12-01

    The Müller & Schumann (M&S) view of drug use is courageous and compelling, with radical implications for drug policy and research. It implies that most nations prohibit most drugs that could promote happiness, social capital, and economic growth; that most individuals underuse rather than overuse drugs; and that behavioral scientists could use drugs more effectively in generating hypotheses and collaborating empathically.

  17. Communication, learning and optimal monetary policy

    NARCIS (Netherlands)

    Tesfaselassie, M.F.

    2005-01-01

    The second part of the thesis deals with interest rate policy under inflation targeting when there is uncertainty in the term structure of interest rates emanating from unobserved, possibly volatile, market sentiments. In situations where expectations depend on the state of the economy--the rate of

  18. Optimization of Overflow Policies in Call Centers

    DEFF Research Database (Denmark)

    Koole, G.M.; Nielsen, B.F.; Nielsen, T.B.

    2015-01-01

    We examine how overflow policies in a multi-skill call center should be designed to accommodate performance measures that depend on waiting time percentiles such as service level. This is done using a discrete Markovian approximation of the waiting time of the first customers waiting in line...... and customers are treated in a FCFS order....

  19. Communication, learning and optimal monetary policy

    NARCIS (Netherlands)

    Tesfaselassie, M.F.

    2005-01-01

    The second part of the thesis deals with interest rate policy under inflation targeting when there is uncertainty in the term structure of interest rates emanating from unobserved, possibly volatile, market sentiments. In situations where expectations depend on the state of the economy--the rate of

  20. Choice of optimal replacement of equipment in the warehouse of the company

    Science.gov (United States)

    Baeva, Silvia; Tomov, Kiril

    2016-12-01

    The aim of this paper is to find an optimal replacement of equipment in the warehouse of the company. Real data for the machines are used and are processed with appropriate software. The mathematical model is made for this problem as problem for the shortest path from graph theory. The solution is made by Bellman's principle.

  1. Trade Liberalization and Optimal Environmental Policies in Vertical Related Markets

    Directory of Open Access Journals (Sweden)

    Yan-Shu Lin

    2012-12-01

    Full Text Available This paper establishes a symmetric two-country model with vertically related markets. In the downstream market, there is one firm in each country selling a homogeneous good, whose production generates pollution, to its home and the foreign markets a la Brander (1981. In the intermediate good market, there is also one upstream firm in each country, supplying the intermediate good only to its own country’s downstream market. The upstream firms can choose either price or quantity to maximize their profits. With this setting, the paper examines the optimal environmental policy and how it is affected by the tariff on the final good. It is found that, under free trade, the optimal final-good output with imperfect intermediate-good market will have the same output level as that with perfect intermediate-good market after imposing the optimal emission tax. The optimal environmental tax is smaller and the optimal environmental policy is less likely to be a green strategy under trade liberalization if the market structure in the intermediate good market is imperfect than perfect competition. On the other hand, the optimal environmental tax is necessarily higher if the upstream firm chooses price than quantity. Moreover, the optimal environmental policy is less likely to be a green strategy under trade liberalization if the upstream firms choose quantity than price to maximize their profits.

  2. Asymptotically optimal production policies in dynamic stochastic jobshops with limited buffers

    Science.gov (United States)

    Hou, Yumei; Sethi, Suresh P.; Zhang, Hanqin; Zhang, Qing

    2006-05-01

    We consider a production planning problem for a jobshop with unreliable machines producing a number of products. There are upper and lower bounds on intermediate parts and an upper bound on finished parts. The machine capacities are modelled as finite state Markov chains. The objective is to choose the rate of production so as to minimize the total discounted cost of inventory and production. Finding an optimal control policy for this problem is difficult. Instead, we derive an asymptotic approximation by letting the rates of change of the machine states approach infinity. The asymptotic analysis leads to a limiting problem in which the stochastic machine capacities are replaced by their equilibrium mean capacities. The value function for the original problem is shown to converge to the value function of the limiting problem. The convergence rate of the value function together with the error estimate for the constructed asymptotic optimal production policies are established.

  3. The optimal hormonal replacement modality selection for multiple organ procurement from brain-dead organ donors

    Directory of Open Access Journals (Sweden)

    Mi Z

    2014-12-01

    Full Text Available Zhibao Mi,1 Dimitri Novitzky,2 Joseph F Collins,1 David KC Cooper3 1Cooperative Studies Program Coordinating Center, VA Maryland Health Care Systems, Perry Point, MD, USA; 2Department of Cardiothoracic Surgery, University of South Florida, Tampa, FL, USA; 3Thomas E Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA Abstract: The management of brain-dead organ donors is complex. The use of inotropic agents and replacement of depleted hormones (hormonal replacement therapy is crucial for successful multiple organ procurement, yet the optimal hormonal replacement has not been identified, and the statistical adjustment to determine the best selection is not trivial. Traditional pair-wise comparisons between every pair of treatments, and multiple comparisons to all (MCA, are statistically conservative. Hsu’s multiple comparisons with the best (MCB – adapted from the Dunnett’s multiple comparisons with control (MCC – has been used for selecting the best treatment based on continuous variables. We selected the best hormonal replacement modality for successful multiple organ procurement using a two-step approach. First, we estimated the predicted margins by constructing generalized linear models (GLM or generalized linear mixed models (GLMM, and then we applied the multiple comparison methods to identify the best hormonal replacement modality given that the testing of hormonal replacement modalities is independent. Based on 10-year data from the United Network for Organ Sharing (UNOS, among 16 hormonal replacement modalities, and using the 95% simultaneous confidence intervals, we found that the combination of thyroid hormone, a corticosteroid, antidiuretic hormone, and insulin was the best modality for multiple organ procurement for transplantation. Keywords: best treatment selection, brain-dead organ donors, hormonal replacement, multiple binary endpoints, organ procurement, multiple comparisons

  4. The optimal inventory policy for EPQ model under trade credit

    Science.gov (United States)

    Chung, Kun-Jen

    2010-09-01

    Huang and Huang [(2008), 'Optimal Inventory Replenishment Policy for the EPQ Model Under Trade Credit without Derivatives International Journal of Systems Science, 39, 539-546] use the algebraic method to determine the optimal inventory replenishment policy for the retailer in the extended model under trade credit. However, the algebraic method has its limit of application such that validities of proofs of Theorems 1-4 in Huang and Huang (2008) are questionable. The main purpose of this article is not only to indicate shortcomings but also to present the accurate proofs for Huang and Huang (2008).

  5. Optimal policies for a finite-horizon batching inventory model

    Science.gov (United States)

    Al-Khamis, Talal M.; Benkherouf, Lakdere; Omar, Mohamed

    2014-10-01

    This paper is concerned with finding an optimal inventory policy for the integrated replenishment-production batching model of Omar and Smith (2002). Here, a company produces a single finished product which requires a single raw material and the objective is to minimise the total inventory costs over a finite planning horizon. Earlier work in the literature considered models with linear demand rate function of the finished product. This work proposes a general methodology for finding an optimal inventory policy for general demand rate functions. The proposed methodology is adapted from the recent work of Benkherouf and Gilding (2009).

  6. INFLATION TARGETING – AN OPTIMAL MONETARY POLICY REGIME FOR THE REPUBLIC OF MOLDOVA AT PRESENT

    Directory of Open Access Journals (Sweden)

    Oleg STRATULAT

    2016-03-01

    Full Text Available The National Bank of the Republic of Moldova, as well as other central banks from other neighbouring countries, with the view to promoting the monetary policy, replaced the objective „ achieving and maintaining the national currency stability” with the target “ensuring and maintaining price stability”. This adjustment conditioned the selection of an optimal monetary policy regime to achieve the respective aim. Further to analysis and research there has been adopted the inflation targeting regime in order to determine the exact amount to a variation interval on a 24 month range. Relying on the experience in implementing the inflation targeting regime by the National Bank of Moldova it was determined that this monetary policy regime is the most adequate for the present socio-economic development of the Republic of Moldova.

  7. Optimal Audit Policies with Correlated Types

    OpenAIRE

    M Martin Boyer; Patrick Gonzalez

    2000-01-01

    We propose a multi-agents adverse selection version of Townsend's (1979) model of costly audits where the agents' types are correlated. Audits are used because agents have a limited ability to bear risk so that the Full Surplus Extraction (FSE) scheme a la Cremer and McLean (1985,1988) and McAfee and Reny (1992) would be suboptimal here. It is shown that Townsend's result of an optimal marginal arbitrage between rent extraction and efficiency does not hold in the case of perfect correlation: ...

  8. Optimal vaccination policies for an SIR model with limited resources.

    Science.gov (United States)

    Zhou, Yinggao; Yang, Kuan; Zhou, Kai; Liang, Yiting

    2014-06-01

    The purpose of the paper is to use analytical method and optimization tool to suggest a vaccination program intensity for a basic SIR epidemic model with limited resources for vaccination. We show that there are two different scenarios for optimal vaccination strategies, and obtain analytical solutions for the optimal control problem that minimizes the total cost of disease under the assumption of daily vaccine supply being limited. These solutions and their corresponding optimal control policies are derived explicitly in terms of initial conditions, model parameters and resources for vaccination. With sufficient resources, the optimal control strategy is the normal Bang-Bang control. However, with limited resources, the optimal control strategy requires to switch to time-variant vaccination.

  9. The impact of drug reimbursement policy on rates of testosterone replacement therapy among older men.

    Directory of Open Access Journals (Sweden)

    Jolanta Piszczek

    Full Text Available Despite a lack of data describing the long-term efficacy and safety of testosterone replacement therapy (TRT, prescribing of testosterone to older men has increased with the availability of topical formulations. The magnitude of this increase and the impact of formulary restrictions on testosterone prescribing are poorly characterized.We conducted a time series analysis using the linked health administrative records of men aged 66 years or older in Ontario, Canada between January 1, 1997 and March 31, 2012. We used interventional autoregressive integrated moving average models to examine the impact of a restrictive drug reimbursement policy on testosterone prescribing and examined the demographic profile of men initiating testosterone in the final 2 years of the study period.A total of 28,477 men were dispensed testosterone over the study period. Overall testosterone prescribing declined 27.9% in the 6 months following the implementation of the restriction policy (9.5 to 6.9 men per 1000 eligible; p<0.01. However, the overall decrease was temporary and testosterone use exceeded pre-policy levels by the end of the study period (11.0 men per 1000 eligible, largely driven by prescriptions for topical testosterone (4.8 men per 1000 eligible. Only 6.3% of men who initiated testosterone had a documented diagnosis of hypogonadism, the main criteria for TRT reimbursement according to the new policy.Government-imposed restrictions did not influence long-term prescribing of testosterone to older men. By 2012, approximately 1 in every 90 men aged 66 or older was being treated with TRT, most with topical formulations.

  10. The impact of drug reimbursement policy on rates of testosterone replacement therapy among older men.

    Science.gov (United States)

    Piszczek, Jolanta; Mamdani, Muhammad; Antoniou, Tony; Juurlink, David N; Gomes, Tara

    2014-01-01

    Despite a lack of data describing the long-term efficacy and safety of testosterone replacement therapy (TRT), prescribing of testosterone to older men has increased with the availability of topical formulations. The magnitude of this increase and the impact of formulary restrictions on testosterone prescribing are poorly characterized. We conducted a time series analysis using the linked health administrative records of men aged 66 years or older in Ontario, Canada between January 1, 1997 and March 31, 2012. We used interventional autoregressive integrated moving average models to examine the impact of a restrictive drug reimbursement policy on testosterone prescribing and examined the demographic profile of men initiating testosterone in the final 2 years of the study period. A total of 28,477 men were dispensed testosterone over the study period. Overall testosterone prescribing declined 27.9% in the 6 months following the implementation of the restriction policy (9.5 to 6.9 men per 1000 eligible; ptestosterone use exceeded pre-policy levels by the end of the study period (11.0 men per 1000 eligible), largely driven by prescriptions for topical testosterone (4.8 men per 1000 eligible). Only 6.3% of men who initiated testosterone had a documented diagnosis of hypogonadism, the main criteria for TRT reimbursement according to the new policy. Government-imposed restrictions did not influence long-term prescribing of testosterone to older men. By 2012, approximately 1 in every 90 men aged 66 or older was being treated with TRT, most with topical formulations.

  11. Handling Practicalities in Agricultural Policy Optimization for Water Quality Improvements

    Science.gov (United States)

    Bilevel and multi-objective optimization methods are often useful to spatially target agri-environmental policy throughout a watershed. This type of problem is complex and is comprised of a number of practicalities: (i) a large number of decision variables, (ii) at least two inte...

  12. Optimization of ACC system spacing policy on curved highway

    Science.gov (United States)

    Ma, Jun; Qian, Kun; Gong, Zaiyan

    2017-05-01

    The paper optimizes the original spacing policy when adopting VTH (Variable Time Headway), proposes to introduce the road curve curvature K to the spacing policy to cope with following the wrong vehicle or failing to follow the vehicle owing to the radar limitation of curve in ACC system. By utilizing MATLAB/Simulink, automobile longitudinal dynamics model is established. At last, the paper sets up such three common cases as the vehicle ahead runs at a uniform velocity, an accelerated velocity and hits the brake suddenly, simulates these cases on the curve with different curvature, analyzes the curve spacing policy in the perspective of safety and vehicle following efficiency and draws the conclusion whether the optimization scheme is effective or not.

  13. Performance Evaluation of the Random Replacement Policy for Networks of Caches

    CERN Document Server

    Gallo, Massimo; Muscariello, Luca; Simonian, Alain; Tanguy, Christian

    2012-01-01

    The overall performance of content distribution networks as well as recently proposed information-centric networks rely on both memory and bandwidth capacities. In this framework, the hit ratio is the key performance indicator which captures the bandwidth / memory tradeo? for a given global performance.This paper focuses on the estimation of the hit ratio in a network of caches that employ the Random replacement policy. Assuming that requests are independent and identically distributed, general expressions of miss probabilities for a single Random cache are provided as well as exact results for specif?c popularity distributions. Moreover, for any Zipf popularity distribution with exponent ? > 1, we obtain asymptotic equivalents for the miss probability in the case of large cache size. We extend the analysis to networks of Random caches, when the topology is either a line or a homogeneous tree. In that case, approximations for miss probabilities across the network are derived by assuming that miss events at an...

  14. Spare parts sharing with joint optimization of maintenance and inventory policies

    DEFF Research Database (Denmark)

    Larsen, Christian; Wong, Hartanto Wijaya; Nielsen, Lars Relund

    inventory policies for both a single- and a multi-company problem. The cost savings obtained as a result of sharing are evaluated. A number of cost allocation schemes, making all the companies involved being better off by sharing the spare parts rather than acting independently, are developed.......We consider a collaborative arrangement where a number of companies are willing to share expensive spare parts, required for both failure replacement and preventive maintenance purposes. We develop a discrete-time Markov decision model for the joint optimization of maintenance and spare parts...

  15. A periodic inspection and replacement policy for systems subject to competing failure modes due to degradation and traumatic events

    Energy Technology Data Exchange (ETDEWEB)

    Huynh, K.T., E-mail: tuan.huynh@utt.f [Universite de technologie de Troyes, Institut Charles Delaunay and STMR UMR CNRS 6279-12, rue Marie Curie, BP2060, 10010 Troyes cedex (France); Barros, A., E-mail: anne.barros@utt.f [Universite de technologie de Troyes, Institut Charles Delaunay and STMR UMR CNRS 6279-12, rue Marie Curie, BP2060, 10010 Troyes cedex (France); Berenguer, C., E-mail: christophe.berenguer@utt.f [Universite de technologie de Troyes, Institut Charles Delaunay and STMR UMR CNRS 6279-12, rue Marie Curie, BP2060, 10010 Troyes cedex (France); Castro, I.T., E-mail: inmatorres@unex.e [Departamento de Matematicas, Escuela Politecnica, 10071 Caceres (Spain)

    2011-04-15

    This paper deals with the condition-based maintenance of single-unit systems which are subject to the competing and dependent failures due deterioration and traumatic shock events. The main aim is to provide a model to assess the value of condition monitoring information for the maintenance decision-making. A condition-based periodic inspection/replacement policy is developed and compared with a benchmark time-based block replacement policy. Numerical results show that it is indeed useful to follow closely the actual evolution of the system to adapt the maintenance decisions to the true system state to improve the performance of maintenance policies. The analysis of the maintenance costs savings can be used to justify or not the choice to implement a policy based on condition monitoring information and to invest in condition monitoring devices.

  16. Input-output interactions and optimal monetary policy

    DEFF Research Database (Denmark)

    Petrella, Ivan; Santoro, Emiliano

    2011-01-01

    This paper deals with the implications of factor demand linkages for monetary policy design in a two-sector dynamic general equilibrium model. Part of the output of each sector serves as a production input in both sectors, in accordance with a realistic input–output structure. Strategic...... complementarities induced by factor demand linkages significantly alter the transmission of shocks and amplify the loss of social welfare under optimal monetary policy, compared to what is observed in standard two-sector models. The distinction between value added and gross output that naturally arises...

  17. Optimal policies for identification of stochastic linear systems

    Science.gov (United States)

    Lopez-Toledo, A. A.; Athans, M.

    1975-01-01

    The problem of designing closed-loop policies for identification of multiinput-multioutput linear discrete-time systems with random time-varying parameters is considered in this paper using a Bayesian approach. A sensitivity index gives a measure of performance for the closed-loop laws. The computation of the optimal laws is shown to be nontrivial, an exercise in stochastic control, but open-loop, affine, and open-loop feedback optimal inputs are shown to yield tractable problems. Numerical examples are given. For time-invariant systems, the criterion considered is shown to be related to the trace of the information matrix associated with the system.

  18. Optimal Transmission Policies for Energy Harvesting Two-hop Networks

    CERN Document Server

    Orhan, Oner

    2012-01-01

    In this paper, a two-hop communication system with energy harvesting nodes is considered. Unlike battery powered wireless nodes, both the source and the relay are able to harvest energy from environment during communication, therefore, both data and energy causality over the two hops need to be considered. Assuming both nodes know the harvested energies in advance, properties of optimal transmission policies to maximize the delivered data by a given deadline are identified. Using these properties, optimal power allocation and transmission schedule for the case in which both nodes harvest two energy packets is developed.

  19. Optimal insemination and replacement decisions to minimize the cost of pathogen-specific clinical mastitis in dairy cows.

    Science.gov (United States)

    Cha, E; Kristensen, A R; Hertl, J A; Schukken, Y H; Tauer, L W; Welcome, F L; Gröhn, Y T

    2014-01-01

    Mastitis is a serious production-limiting disease, with effects on milk yield, milk quality, and conception rate, and an increase in the risk of mortality and culling. The objective of this study was 2-fold: (1) to develop an economic optimization model that incorporates all the different types of pathogens that cause clinical mastitis (CM) categorized into 8 classes of culture results, and account for whether the CM was a first, second, or third case in the current lactation and whether the cow had a previous case or cases of CM in the preceding lactation; and (2) to develop this decision model to be versatile enough to add additional pathogens, diseases, or other cow characteristics as more information becomes available without significant alterations to the basic structure of the model. The model provides economically optimal decisions depending on the individual characteristics of the cow and the specific pathogen causing CM. The net returns for the basic herd scenario (with all CM included) were $507/cow per year, where the incidence of CM (cases per 100 cow-years) was 35.6, of which 91.8% of cases were recommended for treatment under an optimal replacement policy. The cost per case of CM was $216.11. The CM cases comprised (incidences, %) Staphylococcus spp. (1.6), Staphylococcus aureus (1.8), Streptococcus spp. (6.9), Escherichia coli (8.1), Klebsiella spp. (2.2), other treated cases (e.g., Pseudomonas; 1.1), other not treated cases (e.g., Trueperella pyogenes; 1.2), and negative culture cases (12.7). The average cost per case, even under optimal decisions, was greatest for Klebsiella spp. ($477), followed by E. coli ($361), other treated cases ($297), and other not treated cases ($280). This was followed by the gram-positive pathogens; among these, the greatest cost per case was due to Staph. aureus ($266), followed by Streptococcus spp. ($174) and Staphylococcus spp. ($135); negative culture had the lowest cost ($115). The model recommended treatment for

  20. Optimal ordering policies for continuous review perishable inventory models.

    Science.gov (United States)

    Weiss, H J

    1980-01-01

    This paper extends the notions of perishable inventory models to the realm of continuous review inventory systems. The traditional perishable inventory costs of ordering, holding, shortage or penalty, disposal and revenue are incorporated into the continuous review framework. The type of policy that is optimal with respect to long run average expected cost is presented for both the backlogging and lost-sales models. In addition, for the lost-sales model the cost function is presented and analyzed.

  1. Optimal Fluxes, Reaction Replaceability, and Response to Enzymopathies in the Human Red Blood Cell

    Directory of Open Access Journals (Sweden)

    A. De Martino

    2010-01-01

    most harmful reaction knockouts. The integration of combinatorial methods with sampling techniques to explore the space of viable flux states may provide crucial insights on this issue. We assess the replaceability of every metabolic conversion in the human red blood cell by enumerating the alternative paths from substrate to product, obtaining a complete map of he potential damage of single enzymopathies. Sampling the space of optimal steady state fluxes in the healthy and in the mutated cell reveals both correlations and complementarity between topologic and dynamical aspects.

  2. ERROR ANALYSIS OF AN APPROXIMATE OPTIMAL POLICY FOR AN INVENTORY SYSTEM WITH STOCHASTIC AND CONTINUOUS DEMANDS

    OpenAIRE

    WEI GENG; JIANYONG LIU; XIAOBO ZHAO

    2012-01-01

    For a periodic-review inventory system with stochastic and continuous demands and without setup costs, it is known that there exists a base-stock policy to be optimal. For a finite-horizon system with non-stationary parameters, it is essential to find approximate optimal policies because of the computational intractability of finding the optimal policy. This paper provides an approach, by which an analytical bound of the error between the costs of the approximate optimal policy and the optima...

  3. Light weight replacement and the optimization design of bumper beam based on crash safety

    Institute of Scientific and Technical Information of China (English)

    Zhang Jingwen; Ma Mingtu; Fan Tiqiang; Zhao Qingjiang; Li Yang

    2014-01-01

    Bumper beam is one of the key structural parts,which plays an important role in the frontal crashes of automobile. With the global trend of light-weighted automotive parts,the light weight of bumper beam at-tracts extensive attention of automobile manufacturers,and hot stamping technology with significant weight ad-vantage has become one of the main light weight measures for bumper beam. The quasi-static press,low speed crash and frontal crash simulation models of bumper beam were established according to its actual working con-ditions in the automobile crashes. The feasibility of replacing normal steel bumper beam with hot stamping bum-per beam was analyzed. Meanwhile,the stiffeners in the front face of hot stamping bumper beam were opti-mized with topography optimization in order to further improve its performances.

  4. Optimal policy for mitigating emissions in the European transport sector

    Science.gov (United States)

    Leduc, Sylvain; Piera, Patrizio; Sennai, Mesfun; Igor, Staritsky; Berien, Elbersen; Tijs, Lammens; Florian, Kraxner

    2017-04-01

    A geographic explicit techno-economic model, BeWhere (www.iiasa.ac.at/bewhere), has been developed at the European scale (Europe 28, the Balkans countries, Turkey, Moldavia and Ukraine) at a 40km grid size, to assess the potential of bioenergy from non-food feedstock. Based on the minimization of the supply chain from feedstock collection to the final energy product distribution, the model identifies the optimal bioenergy production plants in terms of spatial location, technology and capacity. The feedstock of interests are woody biomass (divided into eight types from conifers and non-conifers) and five different crop residuals. For each type of feedstock, one or multiple technologies can be applied for either heat, electricity or biofuel production. The model is run for different policy tools such as carbon cost, biofuel support, or subsidies, and the optimal mix of technologies and biomass needed is optimized to reach a production cost competitive against the actual reference system which is fossil fuel based. From this approach, the optimal mix of policy tools that can be applied country wide in Europe will be identified. The preliminary results show that high carbon tax and biofuel support contribute to the development of large scale biofuel production based on woody biomass plants mainly located in the northern part of Europe. Finally the highest emission reduction is reached with low biofuel support and high carbon tax evenly distributed in Europe.

  5. 76 FR 27649 - HIV/AIDS Bureau Policy Notice 11-01 (Replaces Policy Notice 99-02)

    Science.gov (United States)

    2011-05-12

    ... HUMAN SERVICES Health Resources and Services Administration HIV/AIDS Bureau Policy Notice 11-01...: Final Notice. SUMMARY: The Health Resources and Services Administration, HIV/AIDS Bureau (HAB) Policy Notice 99-02 established policies for the use of Ryan White HIV/AIDS Program funds authorized under...

  6. Optimal Decomposition of Service Level Objectives into Policy Assertions

    Directory of Open Access Journals (Sweden)

    Yousef Rastegari

    2015-01-01

    Full Text Available WS-agreement specifies quality objectives that each partner is obligated to provide. To meet quality objectives, the corresponding partner should apply appropriate policy assertions to its web services and adjust their parameters accordingly. Transformation of WS-CDL to WSBPEL is addressed in some related works, but neither of them considers quality aspects of transformation nor run-time adaptation. Here, in conformance with web services standards, we propose an optimal decomposition method to make a set of WS-policy assertions. Assertions can be applied to WSBPEL elements and affect their run-time behaviors. The decomposition method achieves the best outcome for a performance indicator. It also guarantees the lowest adaptation overhead by reducing the number of service reselections. We considered securities settlement case study to prototype and evaluate the decomposition method. The results show an acceptable threshold between customer satisfaction—the targeted performance indicator in our case study—and adaptation overhead.

  7. Optimal Decomposition of Service Level Objectives into Policy Assertions.

    Science.gov (United States)

    Rastegari, Yousef; Shams, Fereidoon

    2015-01-01

    WS-agreement specifies quality objectives that each partner is obligated to provide. To meet quality objectives, the corresponding partner should apply appropriate policy assertions to its web services and adjust their parameters accordingly. Transformation of WS-CDL to WSBPEL is addressed in some related works, but neither of them considers quality aspects of transformation nor run-time adaptation. Here, in conformance with web services standards, we propose an optimal decomposition method to make a set of WS-policy assertions. Assertions can be applied to WSBPEL elements and affect their run-time behaviors. The decomposition method achieves the best outcome for a performance indicator. It also guarantees the lowest adaptation overhead by reducing the number of service reselections. We considered securities settlement case study to prototype and evaluate the decomposition method. The results show an acceptable threshold between customer satisfaction-the targeted performance indicator in our case study-and adaptation overhead.

  8. E-money: Efficiency, stability and optimal policy

    OpenAIRE

    Chiu, Jonathan; Wong, Tsz-Nga

    2014-01-01

    What makes e-money more special than cash? Is the introduction of e-money necessarily welfare enhancing? Is an e-money system necessarily stable? What is the optimal way to design an efficient and stable e-money scheme? This paper provides a first attempt to develop a micro-founded, dynamic, general-equilibrium model of e-money for investigating these policy issues. We first identify some superior features of e-money which help mitigate informational frictions and enhance social welfare in a ...

  9. Optimization of fly ash as sand replacement materials (SRM) in cement composites containing coconut fiber

    Science.gov (United States)

    Nadzri, N. I. M.; Jamaludin, S. B.; Mazlee, M. N.; Jamal, Z. A. Z.

    2016-07-01

    The need of utilizing industrial and agricultural wastes is very important to maintain sustainability. These wastes are often incorporated with cement composites to improve performances in term of physical and mechanical properties. This study presents the results of the investigation of the response of cement composites containing coconut fiber as reinforcement and fly ash use as substitution of sand at different hardening days. Hardening periods of time (7, 14 and 28 days) were selected to study the properties of cement composites. Optimization result showed that 20 wt. % of fly ash (FA) is a suitable material for sand replacement (SRM). Meanwhile 14 days of hardening period gave highest compressive strength (70.12 MPa) from the cement composite containing 9 wt. % of coconut fiber and fly ash. This strength was comparable with the cement without coconut fiber (74.19 MPa) after 28 days of curing.

  10. Replacement policy in a system under shocks following a Markovian arrival process

    Energy Technology Data Exchange (ETDEWEB)

    Montoro-Cazorla, Delia [Department of Statistics and Operational Research, University of Jaen (Spain); Perez-Ocon, Rafael [Department of Statistics and Operational Research, University of Granada, Granada (Spain)], E-mail: rperezo@ugr.es; Carmen Segovia, Maria del [Departamento de Estadistica e I.O., University of Granada, Granada (Spain)

    2009-02-15

    We present a system subject to shocks that arrive following a Markovian arrival process. The system is minimally repaired. It is replaced when a certain number of shocks arrive. A general model where the replacements are governed by a discrete phase-type distribution is studied. For this system, the Markov process governing the system is constructed, and the interarrival times between replacements and the number of replacements are calculated. A special case of this system is when it can stand a prefixed number of shocks. For this new system, the same performance measures are calculated. The systems are considered in transient and stationary regime.

  11. Optimal subsidy policy for accelerating the diffusion of green products

    Directory of Open Access Journals (Sweden)

    Hongguang Peng

    2013-06-01

    Full Text Available Purpose: We consider a dynamic duopoly market in which two firms respectively produce green products and conventional products. The two types of product can substitute each other in some degree. Their demand rates depend on not only prices but the consumers’ increasing environmental awareness. Too high initial cost relative to conventional products becomes one of the major obstacles that hinder the adoption of green products. The government employs subsidy policy to trigger the adoption of green products. The purpose of the paper is to explore the optimal subsidy strategy to fulfill the government’s objective. Design/methodology/approach: We suppose the players in the game employ open-loop strategies, which make sense since the government generally cannot alter his policy for political and economic purposes. We take a differential game approach and use backward induction to analyze the firms’ pricing strategy under Cournot competition, and then focus upon a Stackelberg equilibrium to find the optimal subsidy strategy of the government. Findings: The results show that the more remarkable the energy or environmental performance, or the bigger the initial cost of green products, the higher the subsidy level should be. Due to the increasing environmental awareness and the learning curve, the optimal subsidy level decreases over time. Research limitations/implications: In our model several simplifying assumptions are made to keep the analysis more tractable. In particular, we have assumed only one type of green product. In reality several types of product with different energy or environmental performances exist. Our research can be extended in future work to take into account product differentiation on energy or environmental performance and devise a discriminatory subsidy policy accordingly. Originality/value: In the paper we set the objective of the government as minimizing the total social cost induced by the energy consumption or

  12. The optimal time path of clean energy R&D policy when patents have finite lifetime

    NARCIS (Netherlands)

    Gerlagh, R.; Kverndokk, S.; Rosendahl, K.E.

    We study the optimal time path for clean energy innovation policy. In a model with emission reduction through clean energy deployment, and with R&D increasing the overall productivity of clean energy, we describe optimal R&D policies jointly with emission pricing policies. We find that while

  13. The optimal time path of clean energy R&D policy when patents have finite lifetime

    NARCIS (Netherlands)

    Gerlagh, R.; Kverndokk, S.; Rosendahl, K.E.

    2014-01-01

    We study the optimal time path for clean energy innovation policy. In a model with emission reduction through clean energy deployment, and with R&D increasing the overall productivity of clean energy, we describe optimal R&D policies jointly with emission pricing policies. We find that while emissio

  14. Optimal reservoir operation policies using novel nested algorithms

    Science.gov (United States)

    Delipetrev, Blagoj; Jonoski, Andreja; Solomatine, Dimitri

    2015-04-01

    optimization algorithm into the state transition that lowers the starting problem dimension and alleviates the curse of dimensionality. The algorithms can solve multi-objective optimization problems, without significantly increasing the complexity and the computational expenses. The algorithms can handle dense and irregular variable discretization, and are coded in Java as prototype applications. The three algorithms were tested at the multipurpose reservoir Knezevo of the Zletovica hydro-system located in the Republic of Macedonia, with eight objectives, including urban water supply, agriculture, ensuring ecological flow, and generation of hydropower. Because the Zletovica hydro-system is relatively complex, the novel algorithms were pushed to their limits, demonstrating their capabilities and limitations. The nSDP and nRL derived/learned the optimal reservoir policy using 45 (1951-1995) years historical data. The nSDP and nRL optimal reservoir policy was tested on 10 (1995-2005) years historical data, and compared with nDP optimal reservoir operation in the same period. The nested algorithms and optimal reservoir operation results are analysed and explained.

  15. Optimizing Wind And Hydropower Generation Within Realistic Reservoir Operating Policy

    Science.gov (United States)

    Magee, T. M.; Clement, M. A.; Zagona, E. A.

    2012-12-01

    Previous studies have evaluated the benefits of utilizing the flexibility of hydropower systems to balance the variability and uncertainty of wind generation. However, previous hydropower and wind coordination studies have simplified non-power constraints on reservoir systems. For example, some studies have only included hydropower constraints on minimum and maximum storage volumes and minimum and maximum plant discharges. The methodology presented here utilizes the pre-emptive linear goal programming optimization solver in RiverWare to model hydropower operations with a set of prioritized policy constraints and objectives based on realistic policies that govern the operation of actual hydropower systems, including licensing constraints, environmental constraints, water management and power objectives. This approach accounts for the fact that not all policy constraints are of equal importance. For example target environmental flow levels may not be satisfied if it would require violating license minimum or maximum storages (pool elevations), but environmental flow constraints will be satisfied before optimizing power generation. Additionally, this work not only models the economic value of energy from the combined hydropower and wind system, it also captures the economic value of ancillary services provided by the hydropower resources. It is recognized that the increased variability and uncertainty inherent with increased wind penetration levels requires an increase in ancillary services. In regions with liberalized markets for ancillary services, a significant portion of hydropower revenue can result from providing ancillary services. Thus, ancillary services should be accounted for when determining the total value of a hydropower system integrated with wind generation. This research shows that the end value of integrated hydropower and wind generation is dependent on a number of factors that can vary by location. Wind factors include wind penetration level

  16. Optimal dynamic pricing and replenishment policies for deteriorating items

    Directory of Open Access Journals (Sweden)

    Masoud Rabbani

    2014-08-01

    Full Text Available Marketing strategies and proper inventory replenishment policies are often incorporated by enterprises to stimulate demand and maximize profit. The aim of this paper is to represent an integrated model for dynamic pricing and inventory control of deteriorating items. To reflect the dynamic characteristic of the problem, the selling price is defined as a time-dependent function of the initial selling price and the discount rate. In this regard, the price is exponentially discounted to compensate negative impact of the deterioration. The planning horizon is assumed to be infinite and the deterioration rate is time-dependent. In addition to price, the demand rate is dependent on advertisement as a powerful marketing tool. Several theoretical results and an iterative solution algorithm are developed to provide the optimal solution. Finally, to show validity of the model and illustrate the solution procedure, numerical results are presented.

  17. Optimal accounting policies under financial constraints: aggressive versus conservative

    OpenAIRE

    Masatomo Akita; Yusuke Osaki

    2011-01-01

    We examine how severity of financial constraints influences firms' choices of accounting policies. This paper shows that firms with mild financial constraints choose an aggressive accounting policy and those with severe financial constraints choose a conservative accounting policy.

  18. An optimal inventory policy under certainty distributed demand for cutting tools with stochastically distributed lifespan

    National Research Council Canada - National Science Library

    Li, Cun Rong; Cheng, Jiadong

    2015-01-01

    .... An optimal inventory policy with general demand (OIPGD) was developed with which the allowable stopping time for tools, order-up-to-level inventory, and order cycle can be optimally determined by an exhaustive...

  19. Is the optimal intervention policy UC superior to the suboptimal policy MFPT over inferred probabilistic Boolean network models?

    Science.gov (United States)

    Zan, X Z; Liu, W B; Hu, M X; Shen, L Z

    2016-12-19

    A salient problem in translational genomics is the use of gene regulatory networks to determine therapeutic intervention strategies. Theoretically, in a complete network, the optimal policy performs better than the suboptimal policy. However, this theory may not hold if we intervene in a system based on a control policy derived from imprecise inferred networks, especially in the small-sample scenario. In this paper, we compare the performance of the unconstrained (UC) policy with that of the mean-first-passage-time (MFPT) policy in terms of the quality of the determined control gene and the effectiveness of the policy. Our simulation results reveal that the quality of the control gene determined by the robust MFPT policy is better in the small-sample scenario, whereas the sensitive UC policy performs better in the large-sample scenario. Furthermore, given the same control gene, the MFPT policy is more efficient than the UC policy for the small-sample scenario. Owing to these two features, the MFPT policy performs better in the small-sample scenario and the UC policy performs better only in the large-sample scenario. Additionally, using a relatively complex model (gene number N is more than 1) is beneficial for the intervention process, especially for the sensitive UC policy.

  20. Optimizing glucocorticoid replacement therapy in severely adrenocorticotropin-deficient hypopituitary male patients.

    Science.gov (United States)

    Behan, Lucy-Ann; Rogers, Bairbre; Hannon, Mark J; O'Kelly, Patrick; Tormey, William; Smith, Diarmuid; Thompson, Christopher J; Agha, Amar

    2011-10-01

    The optimal replacement regimen of hydrocortisone in adults with severe ACTH deficiency remains unknown. Management strategies vary from treatment with 15-30 mg or higher in daily divided doses, reflecting the paucity of prospective data on the adequacy of different glucocorticoid regimens. Primarily to define the hydrocortisone regimen which results in a 24 h cortisol profile that most closely resembles that of healthy controls and secondarily to assess the impact on quality of life (QoL). Ten male hypopituitary patients with severe ACTH deficiency (basal cortisol <100 nm and peak response to stimulation <400 nm) were enrolled in a prospective, randomized, crossover study of 3 hydrocortisone dose regimens. Following 6 weeks of each regimen patients underwent 24 h serum cortisol sampling and QoL assessment with the Short Form 36 (SF36) and the Nottingham Health Profile (NHP) questionnaires. Free cortisol was calculated using Coolen's equation. All results were compared to those of healthy, matched controls. Corticosteroid binding globulin (CBG) was significantly lower across all dose regimens compared to controls (P < 0·05). The lower dose regimen C (10 mg mane/5 mg tarde) produced a 24 h free cortisol profile (FCP) which most closely resembled that of controls. Both regimen A(20 mg mane/10 mg tarde) and B(10 mg mane/10 mg tarde) produced supraphysiological post-absorption peaks. There was no significant difference in QoL in patients between the three regimens, however energy level was significantly lower across all dose regimens compared to controls (P < 0·001). The lower dose of hydrocortisone (10 mg/5 mg) produces a more physiological cortisol profile, without compromising QoL, compared to higher doses still used in clinical practice. This may have important implications in these patients, known to have excess cardiovascular mortality. © 2011 Blackwell Publishing Ltd.

  1. Optimizing glucocorticoid replacement therapy in severely adrenocorticotropin-deficient hypopituitary male patients.

    LENUS (Irish Health Repository)

    Behan, Lucy-Ann

    2012-02-01

    BACKGROUND: The optimal replacement regimen of hydrocortisone in adults with severe ACTH deficiency remains unknown. Management strategies vary from treatment with 15-30 mg or higher in daily divided doses, reflecting the paucity of prospective data on the adequacy of different glucocorticoid regimens. OBJECTIVE: Primarily to define the hydrocortisone regimen which results in a 24 h cortisol profile that most closely resembles that of healthy controls and secondarily to assess the impact on quality of life (QoL). DESIGN: Ten male hypopituitary patients with severe ACTH deficiency (basal cortisol <100 nm and peak response to stimulation <400 nm) were enrolled in a prospective, randomized, crossover study of 3 hydrocortisone dose regimens. Following 6 weeks of each regimen patients underwent 24 h serum cortisol sampling and QoL assessment with the Short Form 36 (SF36) and the Nottingham Health Profile (NHP) questionnaires. Free cortisol was calculated using Coolen\\'s equation. All results were compared to those of healthy, matched controls. RESULTS: Corticosteroid binding globulin (CBG) was significantly lower across all dose regimens compared to controls (P < 0.05). The lower dose regimen C (10 mg mane\\/5 mg tarde) produced a 24 h free cortisol profile (FCP) which most closely resembled that of controls. Both regimen A(20 mg mane\\/10 mg tarde) and B(10 mg mane\\/10 mg tarde) produced supraphysiological post-absorption peaks. There was no significant difference in QoL in patients between the three regimens, however energy level was significantly lower across all dose regimens compared to controls (P < 0.001). CONCLUSIONS: The lower dose of hydrocortisone (10 mg\\/5 mg) produces a more physiological cortisol profile, without compromising QoL, compared to higher doses still used in clinical practice. This may have important implications in these patients, known to have excess cardiovascular mortality.

  2. Comparison of Policy Functions from the Optimal Learning and Adaptive Control Frameworks

    NARCIS (Netherlands)

    Kendrick, D.A.; Amman, H.M.|info:eu-repo/dai/nl/070970777

    2008-01-01

    In this paper we turn our attention to comparing the policy function obtained by Beck and Wieland (2002) to the one obtained with adaptive control methods. It is an integral part of the optimal learning method used by Beck and Wieland to obtain a policy function that provides the optimal control as

  3. Spatial targeting of agri-environmental policy using bilevel evolutionary optimization

    Science.gov (United States)

    In this study we describe the optimal designation of agri-environmental policy as a bilevel optimization problem and propose an integrated solution method using a hybrid genetic algorithm. The problem is characterized by a single leader, the agency, that establishes a policy with the goal of optimiz...

  4. Optimal Monetary Policy Cooperation through State-Independent Contracts with Targets

    DEFF Research Database (Denmark)

    Jensen, Henrik

    2000-01-01

    Simple state-independent monetary institutions are shown to secure optimal cooperative policies in a stochastic, linear-quadratic two-country world with international policy spill-overs and national credibility problems. Institutions characterize delegation to independent central bankers facing...... quadratic performance related contracts punishing or rewarding deviations from primary and intermediate policy targets...

  5. Methods, systems, and computer program products for network firewall policy optimization

    Science.gov (United States)

    Fulp, Errin W.; Tarsa, Stephen J.

    2011-10-18

    Methods, systems, and computer program products for firewall policy optimization are disclosed. According to one method, a firewall policy including an ordered list of firewall rules is defined. For each rule, a probability indicating a likelihood of receiving a packet matching the rule is determined. The rules are sorted in order of non-increasing probability in a manner that preserves the firewall policy.

  6. The feasibility of multisectoral policy options aimed at reducing trans fats and encouraging its replacement with healthier oils in India.

    Science.gov (United States)

    Downs, Shauna M; Thow, Anne-Marie; Ghosh-Jerath, Suparna; Leeder, Stephen R

    2015-05-01

    The World Health Organization recommends replacement of trans fat with polyunsaturated fat to reduce cardiovascular disease risk. Although several high-income countries have been successful in reducing trans fat in the food supply, low- and middle-income countries such as India may face additional contextual challenges such as the large informal sector, lack of consumer awareness, less enforcement capacity and low availability and affordability of healthier unsaturated fats. The objective of this study was to examine the feasibility and acceptability of multisectoral policy options aimed at supporting trans fat reduction and its replacement with polyunsaturated fats in India. Multisectoral policy options examined in this study were identified using food supply chain analysis. Semi-structured interviews (n = 17) were conducted with key informants from agriculture, trade, finance, retail, industry, food standards, non-governmental organizations and the health professions to gain their views on the feasibility and acceptability of the policy options. Purposive sampling was used to identify key informants. Data were coded and organized based on key themes. There was support for policies aimed at improving the quality of seeds, supporting farmer co-operatives and developing affordable farming equipment suited to smallholders to improve the production of healthier oils. Increasing the role of the private sector to improve links among producers, processors and retailers may help to streamline the fats supply chain in India. Blending healthier oils with oils high in saturated fat, which are currently readily available, could help to improve the quality of fat in the short term. Improving consumer awareness through mass media campaigns and improved labelling may help increase consumer demand for healthier products. Reorienting agricultural policies to support production of healthier oils will help increase their uptake by industry. Policy coherence across sectors will be

  7. OPTIMAL TRAINING POLICY FOR PROMOTION - STOCHASTIC MODELS OF MANPOWER SYSTEMS

    Directory of Open Access Journals (Sweden)

    V.S.S. Yadavalli

    2012-01-01

    Full Text Available In this paper, the optimal planning of manpower training programmes in a manpower system with two grades is discussed. The planning of manpower training within a given organization involves a trade-off between training costs and expected return. These planning problems are examined through models that reflect the random nature of manpower movement in two grades. To be specific, the system consists of two grades, grade 1 and grade 2. Any number of persons in grade 2 can be sent for training and after the completion of training, they will stay in grade 2 and will be given promotion as and when vacancies arise in grade 1. Vacancies arise in grade 1 only by wastage. A person in grade 1 can leave the system with probability p. Vacancies are filled with persons in grade 2 who have completed the training. It is assumed that there is a perfect passing rate and that the sizes of both grades are fixed. Assuming that the planning horizon is finite and is T, the underlying stochastic process is identified as a finite state Markov chain and using dynamic programming, a policy is evolved to determine how many persons should be sent for training at any time k so as to minimize the total expected cost for the entire planning period T.

  8. Optimal Tax-Transfer Policies, Life-Cycle Labour Supply and Present-Biased Preferences

    DEFF Research Database (Denmark)

    Gunnersen, Lasse Frisgaard; Rasmussen, Bo Sandemann

    Using a two-period model with two types of agents that are characterized by present-biased preferences second-best optimal tax-transfer policies are considered. The paternalistic optimal tax-transfer policy has two main concerns: Income redistribution from high to low ability households...... consequences not only for optimal subsidies to savings but also for optimal marginal income taxes....... and correction of undersaving due to present-biasedness. Policies must comply with incentive-compatibility constraints that restricts both how much income redistribution that can take place and how much savings should be subsidized. A main result is that the degree of present-biasedness has important...

  9. Optimal Production and Inventory Policy for Multiple Products Under Resource Constraints

    OpenAIRE

    Gregory A. DeCroix; Antonio Arreola-Risa

    1998-01-01

    We show that a modified base-stock policy is optimal for multiproduct, infinite-horizon production-inventory systems, where demand for the products is random and the products share a finite resource every period. We characterize the optimal policy for the case of homogeneous products. Because of the difficulty in computing the optimal base-stock levels for the heterogeneous case, we propose a heuristic that is simple enough for practical applications. We present numerical results that suggest...

  10. Intermittently Connected Cloudlet System to Obtain an Optimal Offloading Policy

    Directory of Open Access Journals (Sweden)

    Nadim Akhtar

    2016-09-01

    Full Text Available The great potential has been shown over the performance enhancement for offloading the mobile devices within intensive parts of computation within mobile cloud application. The complete realization for the potential which being mismatch within the particular mobile devices on the resource computing demand and that provide an offer. The request over offloading is connecting the variable network where cloud services are always being in the required process within infrequent, variable connectivity of network and quick response time for relatively incurring the times for long setup and quanta for long time are may be indifferent for the connectivity of network. The requirement over the mobile application is needed more resources for executing the single device task within the fact of mobile devices enhanced capabilities. The problems have been addressed for several computation of offloading the remote cloud services and resources which is locating the computing resources in the cloudlets. The proposed concept is proposing an experimental approach for highlighting the tradeoff of offloading. The proposed architecture of the generic algorithm is performing an integration of mobile cloud computing for automatic offloading to improve the application response time when minimizing the consumption of energy for mobile device. Offloading task within a remote machine is not better than performing task particularly. The particular performance of the task is always better than remote machine. The proposed system is developing an algorithm of optimal offloading for mobile user which considering over the cloudlets availability and local load of user’s. The solution and formulation of the MDP (Markov Decision Process model is for obtaining a policy to the user mobile and minimizing the objective of offloading cost and computation cost.

  11. Optimizing Input/Output Using Adaptive File System Policies

    Science.gov (United States)

    Madhyastha, Tara M.; Elford, Christopher L.; Reed, Daniel A.

    1996-01-01

    Parallel input/output characterization studies and experiments with flexible resource management algorithms indicate that adaptivity is crucial to file system performance. In this paper we propose an automatic technique for selecting and refining file system policies based on application access patterns and execution environment. An automatic classification framework allows the file system to select appropriate caching and pre-fetching policies, while performance sensors provide feedback used to tune policy parameters for specific system environments. To illustrate the potential performance improvements possible using adaptive file system policies, we present results from experiments involving classification-based and performance-based steering.

  12. Statistical Testing of Optimality Conditions in Multiresponse Simulation-Based Optimization (Replaced by Discussion Paper 2007-45)

    NARCIS (Netherlands)

    Bettonvil, B.W.M.; Del Castillo, E.; Kleijnen, Jack P.C.

    2005-01-01

    This paper derives a novel procedure for testing the Karush-Kuhn-Tucker (KKT) first-order optimality conditions in models with multiple random responses.Such models arise in simulation-based optimization with multivariate outputs.This paper focuses on expensive simulations, which have small sample

  13. Optimization of a sponge cake formulation with inulin as fat replacer: structure, physicochemical, and sensory properties.

    Science.gov (United States)

    Rodríguez-García, Julia; Puig, Ana; Salvador, Ana; Hernando, Isabel

    2012-02-01

    The effects of several fat replacement levels (0%, 35%, 50%, 70%, and 100%) by inulin in sponge cake microstructure and physicochemical properties were studied. Oil substitution for inulin decreased significantly (P sponge cake recipe to obtain a new product with additional health benefits and accepted by consumers is achieved. Practical Application:  In this study, fat is replaced by inulin in cakes, which is a fiber mainly obtained from chicory roots. Sponge cake formulations with reductions in fat content up to 70% are achieved. These high-quality products can be labeled as "reduced in fat" according to U.S. FDA (2009) and EU regulations (European-Union 2006).

  14. Optimization on bicriterion policies for M/G/1 system with second optional service

    Institute of Scientific and Technical Information of China (English)

    Jau-chuan KE; Yunn-kuang CHU

    2008-01-01

    We compare the optimal operating cost of the two bicriterion policies, p,T and p,N, for an M/G/1 queueing system with second optional service, in which the length of the vacation period is randomly controlled either by the number of arrivals during the idle period or by a timer. After all the customers are served in the queue exhaustively, the server immediately takes a vacation and may operate p, T policy or p,N policy. For the two bicriterion policies, the total average cost function per unit time is developed to search the optimal stationary operating policies at a minimum cost. Based upon the optimal cost the explicit forms for joint optimum threshold values of (p,T) and (p,N) are obtained.

  15. The complete proof on the optimal ordering policy under cash discount and trade credit

    Science.gov (United States)

    Chung, Kun-Jen

    2010-04-01

    Huang ((2005), 'Buyer's Optimal Ordering Policy and Payment Policy under Supplier Credit', International Journal of Systems Science, 36, 801-807) investigates the buyer's optimal ordering policy and payment policy under supplier credit. His inventory model is correct and interesting. Basically, he uses an algebraic method to locate the optimal solution of the annual total relevant cost TRC(T) and ignores the role of the functional behaviour of TRC(T) in locating the optimal solution of it. However, as argued in this article, Huang needs to explore the functional behaviour of TRC(T) to justify his solution. So, from the viewpoint of logic, the proof about Theorem 1 in Huang has some shortcomings such that the validity of Theorem 1 in Huang is questionable. The main purpose of this article is to remove and correct those shortcomings in Huang and present the complete proofs for Huang.

  16. Policy Gradient Adaptive Dynamic Programming for Data-Based Optimal Control.

    Science.gov (United States)

    Luo, Biao; Liu, Derong; Wu, Huai-Ning; Wang, Ding; Lewis, Frank L

    2016-11-22

    The model-free optimal control problem of general discrete-time nonlinear systems is considered in this paper, and a data-based policy gradient adaptive dynamic programming (PGADP) algorithm is developed to design an adaptive optimal controller method. By using offline and online data rather than the mathematical system model, the PGADP algorithm improves control policy with a gradient descent scheme. The convergence of the PGADP algorithm is proved by demonstrating that the constructed.

  17. Optimization of fat-reduced ice cream formulation employing inulin as fat replacer via response surface methodology.

    Science.gov (United States)

    Pintor, Aurora; Severiano-Pérez, Patricia; Totosaus, Alfonso

    2014-10-01

    The use of new ingredients like inulin for fat replacement is of wide application in the food industry. The aim of the present work was to reduce the fat content on ice cream formulations. It was possible to reduce up to 25% of butyric and vegetable fats with 3% of inulin, with good textural and sensory characteristics of the final product. The substitution of fat with inulin increased the ice cream mix viscosity, improved air incorporation, and produced ice cream with soft and homogeneous textures. Color characteristics were not affected by the replacement. Hedonic sensory analysis showed that optimized fat-reduced inulin ice cream was not perceived different to commercial vanilla ice cream.

  18. Evaluation of optimal monetary policy strategy in Romania in the context of fulfilment of convergence criteria

    Directory of Open Access Journals (Sweden)

    Monica DAMIAN

    2011-12-01

    Full Text Available Adopting the euro currency implies the fulfilment of Maastricht convergence criteria, which implies a number of challenges for the macroeconomic policy mix, due to the existence of the conflict between them. The paper analyzes empirically the main monetary policy strategy in the context of euro in Romania.The results of the study show that inflation targeting is an optimal monetary policy strategy to achieve real and nominal convergence criteria.

  19. Optimal continuous order quantity (s,S) policies; the 45-degrees algorithm

    NARCIS (Netherlands)

    E.M. Bazsa-Oldenkamp; P. den Iseger

    2002-01-01

    textabstractThe most recent optimization algorithm for (s,S) order policies with continuous demand was developed by Federgruen and Zipkin (1985). This was also the first efficient algorithm, which uses policy iteration instead of discretization. Zheng and Federgruen (1991) developed an even more eff

  20. Comparison of policy functions from optimal learning and adaptive control frameworks

    NARCIS (Netherlands)

    Amman, H.M.; Kendrick, D.A.

    2014-01-01

    In this paper we turn our attention to comparing the policy function obtained by Beck and Wieland (J Econ Dyn Control 26:1359-1377, 2002) to the one obtained with adaptive control methods. It is an integral part of the optimal learning method used by Beck and Wieland to obtain a policy function that

  1. Optimal Service Policies to Remote Customers with Delay-Limits

    NARCIS (Netherlands)

    Berg, M.; van der Duyn Schouten, F.A.; Jansen, J.B.

    1996-01-01

    This work deals with service provision to remote customers.Two examples are: (i) a manufacturer that has to deliver items to customers in a remote destination, and (ii) a company that provides repair and replacement service to distant clients.In both cases the remoteness of customers suggests order

  2. Optimal Service Policies to Remote Customers with Delay-Limits

    NARCIS (Netherlands)

    Berg, M.; van der Duyn Schouten, F.A.; Jansen, J.B.

    1996-01-01

    This work deals with service provision to remote customers.Two examples are: (i) a manufacturer that has to deliver items to customers in a remote destination, and (ii) a company that provides repair and replacement service to distant clients.In both cases the remoteness of customers suggests order

  3. Optimal pricing and replenishment policies for instantaneous deteriorating items with backlogging and trade credit under inflation

    Science.gov (United States)

    Sundara Rajan, R.; Uthayakumar, R.

    2017-04-01

    In this paper we develop an economic order quantity model to investigate the optimal replenishment policies for instantaneous deteriorating items under inflation and trade credit. Demand rate is a linear function of selling price and decreases negative exponentially with time over a finite planning horizon. Shortages are allowed and partially backlogged. Under these conditions, we model the retailer's inventory system as a profit maximization problem to determine the optimal selling price, optimal order quantity and optimal replenishment time. An easy-to-use algorithm is developed to determine the optimal replenishment policies for the retailer. We also provide optimal present value of profit when shortages are completely backlogged as a special case. Numerical examples are presented to illustrate the algorithm provided to obtain optimal profit. And we also obtain managerial implications from numerical examples to substantiate our model. The results show that there is an improvement in total profit from complete backlogging rather than the items being partially backlogged.

  4. Optimal pricing policies for services with consideration of facility maintenance costs

    Science.gov (United States)

    Yeh, Ruey Huei; Lin, Yi-Fang

    2012-06-01

    For survival and success, pricing is an essential issue for service firms. This article deals with the pricing strategies for services with substantial facility maintenance costs. For this purpose, a mathematical framework that incorporates service demand and facility deterioration is proposed to address the problem. The facility and customers constitute a service system driven by Poisson arrivals and exponential service times. A service demand with increasing price elasticity and a facility lifetime with strictly increasing failure rate are also adopted in modelling. By examining the bidirectional relationship between customer demand and facility deterioration in the profit model, the pricing policies of the service are investigated. Then analytical conditions of customer demand and facility lifetime are derived to achieve a unique optimal pricing policy. The comparative statics properties of the optimal policy are also explored. Finally, numerical examples are presented to illustrate the effects of parameter variations on the optimal pricing policy.

  5. Optimizing the Multisectoral Nutrition Policy Cycle: A Systems Perspective.

    Science.gov (United States)

    Lamstein, Sascha; Pomeroy-Stevens, Amanda; Webb, Patrick; Kennedy, Eileen

    2016-12-01

    Based on the data collected in Uganda, Nepal, and Ethiopia, the papers included in this supplement fill a critical gap in evidence regarding multisectoral National Nutrition Action Plans. The studies offer new data and new thinking on how and why governance, effective financial decentralization, and improved accountability all matter for nutrition actions in low-income countries. This introductory paper offers an overview of the current state of evidence and thinking on the multisectoral nutrition policy cycle, including how governance and financing support that process. It also explores the benefits of applying a systems lens to understand the dynamic, enabling processes of the policy cycle-from research to knowledge and ultimately action-and to provide more dynamic and accurate information for nutrition advocacy and evidence-based decision-making. It concludes with key findings from the 5 country-level studies included. Several important themes emerge: the egregious gap in human resources needed for effective nutrition actions in most low-income settings, the value of research on bottlenecks and successes, and the need for routine monitoring of national policies and plans to measure their effectiveness in achieving both their own stated goals and global sustainable development goals. Reviewing these studies together provides a path forward in building stronger, evidence-based multisectoral nutrition policies and supporting implementation of the nutrition activities included within them.

  6. ESD: Power, Politics, and Policy: "Tragic Optimism" from Latin America

    Science.gov (United States)

    González-Gaudiano, Edgar J.

    2016-01-01

    In light of the challenging developmental issues confronting the countries of Latin America, this response article analyzes the power and resistance of education for sustainable development from both theoretical and policy perspectives. Of particular concern are the neo-productivist strategies driving the latest stage of capitalist development.…

  7. Optimal demographic information for policy development in the ...

    African Journals Online (AJOL)

    Erna Kinsey

    Education system planners constantly have to deal with external ... formulating an efficient policy based on it. ... the migration of learners from their own residential areas to schools which are .... The following two extracts from literature show how deep ... The situation is unlikely to get better with time; on the contrary, if the ...

  8. Optimal Inventory Policy for Two-echelon Remanufacturing

    OpenAIRE

    Ferrer, Geraldo

    2007-01-01

    Proceedings Paper (for Acquisition Research Program) We present a two-echelon remanufacturing facility subject to constant demand, in which the disassembly process and the repair process observe stochastic yield. We develop an intuitive scheduling policy and perform a robustness test. Acquisition Research Program

  9. Optimal Control Policy for Environment withScience and Technology Stochastic Occur

    Institute of Scientific and Technical Information of China (English)

    MinggaoXue; ChulinLi; PuGong

    2004-01-01

    In this paper, the control policy for environment with two kinds of irreversibility, which work in opposite directions and uncertainty of cost is regarded as an investment decision. By using real-option theory, the paper presents the model of the optimal control policy for environment under the science and technology that can reduce environment pollution stochastic occur. The paper has discussed the effects of changes in the various parameters on the critical value at which the policy should be adopted. The results show thatthe optimal control policy is quite sensitive to the science and technology which can reduce environment pollution stochastic occur, pointing to the importance of carefully accounting for its impact in determining the control policy for environment.

  10. Gradient-based multiobjective optimization using a distance constraint technique and point replacement

    Science.gov (United States)

    Sato, Yuki; Izui, Kazuhiro; Yamada, Takayuki; Nishiwaki, Shinji

    2016-07-01

    This paper proposes techniques to improve the diversity of the searching points during the optimization process in an Aggregative Gradient-based Multiobjective Optimization (AGMO) method, so that well-distributed Pareto solutions are obtained. First to be discussed is a distance constraint technique, applied among searching points in the objective space when updating design variables, that maintains a minimum distance between the points. Next, a scheme is introduced that deals with updated points that violate the distance constraint, by deleting the offending points and introducing new points in areas of the objective space where searching points are sparsely distributed. Finally, the proposed method is applied to example problems to illustrate its effectiveness.

  11. Optimization of maintenance policy using the proportional hazard model

    Energy Technology Data Exchange (ETDEWEB)

    Samrout, M. [Information Sciences and Technologies Institute, University of Technology of Troyes, 10000 Troyes (France)], E-mail: mohamad.el_samrout@utt.fr; Chatelet, E. [Information Sciences and Technologies Institute, University of Technology of Troyes, 10000 Troyes (France)], E-mail: chatelt@utt.fr; Kouta, R. [M3M Laboratory, University of Technology of Belfort Montbeliard (France); Chebbo, N. [Industrial Systems Laboratory, IUT, Lebanese University (Lebanon)

    2009-01-15

    The evolution of system reliability depends on its structure as well as on the evolution of its components reliability. The latter is a function of component age during a system's operating life. Component aging is strongly affected by maintenance activities performed on the system. In this work, we consider two categories of maintenance activities: corrective maintenance (CM) and preventive maintenance (PM). Maintenance actions are characterized by their ability to reduce this age. PM consists of actions applied on components while they are operating, whereas CM actions occur when the component breaks down. In this paper, we expound a new method to integrate the effect of CM while planning for the PM policy. The proportional hazard function was used as a modeling tool for that purpose. Interesting results were obtained when comparison between policies that take into consideration the CM effect and those that do not is established.

  12. Optimal Inventory Policy for Two-echelon Remanufacturing

    Science.gov (United States)

    2007-04-30

    research presented at the symposium was supported by the Acquisition Chair of the Graduate School of Business & Public Policy at the Naval Postgraduate...research poster show and social events, the Annual Acquisition Research Symposium offers a candid environment where high-ranking Department of Defense (DoD...Foundation and for the Social Sciences and Humanities Council of Canada. He has also reviewed textbooks in the areas of operations management

  13. Pareto Optimal Insurance Policies in the Presence of Administrative Costs

    OpenAIRE

    Aase, Knut K.

    2010-01-01

    In his classical article in The American Economic Review, Arthur Raviv (1979) examines Pareto optimal insurance contracts when there are ex-post insurance costs c induced by the indemnity I for loss x. Raviv’s main result is that a necessary and sufficient condition for the Pareto optimal deductible to be equal to zero is c0(I) = 0 for all I > 0(or I=0). We claim that another type of cost function is called for in household insurance, caused by frequent but relatively small ...

  14. Optimization of the Advertising Policy for a Recreation Park

    NARCIS (Netherlands)

    B. Wierenga (Berend)

    1979-01-01

    textabstractThis paper deals with the problem of the desirable level of advertising expenditure, the optimal distribution of this expenditure in time, and the allocation over the media -- TV, radio, and newspaper -- for a recreation park in the Netherlands. First, a model is specified and estimated,

  15. Towards minimax policies for online linear optimization with bandit feedback

    CERN Document Server

    Bubeck, Sébastien; Kakade, Sham M

    2012-01-01

    We address the online linear optimization problem with bandit feedback. Our contribution is twofold. First, we provide an algorithm (based on exponential weights) with a regret of order $\\sqrt{d n \\log N}$ for any finite action set with $N$ actions, under the assumption that the instantaneous loss is bounded by 1. This shaves off an extraneous $\\sqrt{d}$ factor compared to previous works, and gives a regret bound of order $d \\sqrt{n \\log n}$ for any compact set of actions. Without further assumptions on the action set, this last bound is minimax optimal up to a logarithmic factor. Interestingly, our result also shows that the minimax regret for bandit linear optimization with expert advice in $d$ dimension is the same as for the basic $d$-armed bandit with expert advice. Our second contribution is to show how to use the Mirror Descent algorithm to obtain computationally efficient strategies with minimax optimal regret bounds in specific examples. More precisely we study two canonical action sets: the hypercub...

  16. Optimization of the Advertising Policy for a Recreation Park

    NARCIS (Netherlands)

    B. Wierenga (Berend)

    1979-01-01

    textabstractThis paper deals with the problem of the desirable level of advertising expenditure, the optimal distribution of this expenditure in time, and the allocation over the media -- TV, radio, and newspaper -- for a recreation park in the Netherlands. First, a model is specified and estimated,

  17. On the selection of optimization parameters for an inverse treatment planning replacement of a forward planning technique for prostate cancer.

    Science.gov (United States)

    Hristov, Dimitre H; Moftah, Belal A; Charrois, Colette; Parker, William; Souhami, Luis; Podgorsak, Ervin B

    2002-01-01

    The influence of organ volume sampling, lateral scatter inclusion, and the selection of objectives and constraints on the inverse treatment planning process with a commercial treatment planning system is investigated and suitable parameters are identified for an inverse treatment planning replacement of a clinical forward planning technique for prostate cancer. For the beam geometries of the forward technique, a variable set of parameters is used for the calculation of dose from pencil beams. An optimal set is identified after the evaluation of optimized plans that correspond to different sets of pencil-beam parameters. This set along with a single, optimized set of objectives and constraints is used to perform inverse planning on ten randomly selected patients. The acceptability of the resulting plans is verified by comparisons to the clinical ones calculated with the forward techniques. For the particular commercial treatment planning system, the default values of the pencil beam parameters are found adequate for inverse treatment planning. For all ten patients, the optimized, single set of objectives and constraints results in plans with target coverage comparable to that of the forward plans. Furthermore inverse treatment planning reduces the overall mean rectal and bladder doses by 4.8% and 5.8% of the prescription dose respectively. The study indicates that (i) inverse treatment planning results depend implicitly on the sampling of the dose distribution, (ii) inverse treatment planning results depend on the method used by the dose calculation model to account for scatter, and (iii) for certain sites, a single set of optimization parameters can be used for all patient plans.

  18. Optimal dynamic pricing and replenishment policy for perishable items with inventory-level-dependent demand

    Science.gov (United States)

    Lu, Lihao; Zhang, Jianxiong; Tang, Wansheng

    2016-04-01

    An inventory system for perishable items with limited replenishment capacity is introduced in this paper. The demand rate depends on the stock quantity displayed in the store as well as the sales price. With the goal to realise profit maximisation, an optimisation problem is addressed to seek for the optimal joint dynamic pricing and replenishment policy which is obtained by solving the optimisation problem with Pontryagin's maximum principle. A joint mixed policy, in which the sales price is a static decision variable and the replenishment rate remains to be a dynamic decision variable, is presented to compare with the joint dynamic policy. Numerical results demonstrate the advantages of the joint dynamic one, and further show the effects of different system parameters on the optimal joint dynamic policy and the maximal total profit.

  19. Optimal climate policy is a utopia. From quantitative to qualitative cost-benefit analysis

    Energy Technology Data Exchange (ETDEWEB)

    Van den Bergh, Jeroen C.J.M. [Department of Spatial Economics, Faculty of Economics and Business Administration, and Institute for Environmental Studies, Free University, De Boelelaan 1105, 1081 HV, Amsterdam (Netherlands)

    2004-04-20

    The dominance of quantitative cost-benefit analysis (CBA) and optimality concepts in the economic analysis of climate policy is criticised. Among others, it is argued to be based in a misplaced interpretation of policy for a complex climate-economy system as being analogous to individual inter-temporal welfare optimisation. The transfer of quantitative CBA and optimality concepts reflects an overly ambitious approach that does more harm than good. An alternative approach is to focus the attention on extreme events, structural change and complexity. It is argued that a qualitative rather than a quantitative CBA that takes account of these aspects can support the adoption of a minimax regret approach or precautionary principle in climate policy. This means: implement stringent GHG reduction policies as soon as possible.

  20. Playing games against nature: optimal policies for renewable resource allocation

    CERN Document Server

    Ermon, Stefano; Gomes, Carla P; Selman, Bart

    2012-01-01

    In this paper we introduce a class of Markov decision processes that arise as a natural model for many renewable resource allocation problems. Upon extending results from the inventory control literature, we prove that they admit a closed form solution and we show how to exploit this structure to speed up its computation. We consider the application of the proposed framework to several problems arising in very different domains, and as part of the ongoing effort in the emerging field of Computational Sustainability we discuss in detail its application to the Northern Pacific Halibut marine fishery. Our approach is applied to a model based on real world data, obtaining a policy with a guaranteed lower bound on the utility function that is structurally very different from the one currently employed.

  1. That Was Then, This Is Now: Replacing the Mobile-Optimized Site with Responsive Design

    Directory of Open Access Journals (Sweden)

    Laurie M. Bridges

    2013-12-01

    Full Text Available As mobile technologies continue to evolve, libraries seek sustainable ways to keep up with these changes and to best serve our users.  Previous library mobile usability research has examined tasks users predict they might be likely to perform, but little is known about what users actually do on a mobile-optimized library site.  This research used a combination of survey methodology and web analytics to examine what tasks users actually carry out on a library mobile site.  The results indicate that users perform an array of passive and active tasks and do not want content choices to be limited on mobile devices.  Responsive design is described as a long-term solution for addressing both designers and users’ needs.

  2. Research on optimal policy of single-period inventory management with two suppliers.

    Science.gov (United States)

    Yang, Baimei; Sui, Lihui; Zhu, Peipei

    2014-01-01

    We study a single-period inventory control problem with two independent suppliers. With the first supplier, the buyer incurs a high variable cost but negligible fixed cost; with the second supplier, the buyer incurs a lower variable cost but a positive fixed cost. At the same time, the ordering quantity is limited. We develop the optimal inventory control policy when the holding and shortage cost function is convex. We also conduct some numerical experiments to explore the effects of the fixed setup cost K and the ordering capacity Q on the optimal control policy.

  3. Research on Optimal Policy of Single-Period Inventory Management with Two Suppliers

    Directory of Open Access Journals (Sweden)

    Baimei Yang

    2014-01-01

    Full Text Available We study a single-period inventory control problem with two independent suppliers. With the first supplier, the buyer incurs a high variable cost but negligible fixed cost; with the second supplier, the buyer incurs a lower variable cost but a positive fixed cost. At the same time, the ordering quantity is limited. We develop the optimal inventory control policy when the holding and shortage cost function is convex. We also conduct some numerical experiments to explore the effects of the fixed setup cost K and the ordering capacity Q on the optimal control policy.

  4. Optimal production policy for multi-product with inventory-level-dependent demand in segmented market

    Directory of Open Access Journals (Sweden)

    Singh Yogender

    2013-01-01

    Full Text Available Market segmentation has emerged as the primary means by which firms achieve optimal production policy. In this paper, we use market segmentation approach in multi-product inventory system with inventory-level-dependent demand. The objective is to make use of optimal control theory to solve the inventory-production problem and develop an optimal production policy that minimizes the total cost associated with inventory and production rate in segmented market. First, we consider a single production and inventory problem with multi-destination demand that vary from segment to segment. Further, we describe a single source production and multi destination inventory and demand problem under the assumption that firm may choose independently the inventory directed to each segment. The optimal control is applied to study and solve the proposed problem.

  5. Optimal substrate feeding policy for a fed batch fermentation with substrate and product inhibition kinetics.

    Science.gov (United States)

    Hong, J

    1986-09-01

    The optimal substrate feeding policy for the fed batch fermentation which is governed by product and substrate inhibited kinetics is presented. The conjunction point between nonsingular and singular arcs and the feeding policy along the singular arc are derived analytically in terms of the concentrations of substrate and product and the liquid volume. Thus, it is possible to determine the feeding rate by monitoring the state variables (i.e., closed loop control). As a specific example, an optimization study of the fed batch fermentation for ethanol production by Saccharomyces cerevisiae is presented. It is shown that the optimal feeding patterns are heavily dependent upon the initial conditions. The point selectivity provides the guideline for predicting the optimal feeding patterns and explaining the results of rigorous mathematical analysis.

  6. Transmission with Energy Harvesting Nodes in Fading Wireless Channels: Optimal Policies

    CERN Document Server

    Ozel, Omur; Yang, Jing; Ulukus, Sennur; Yener, Aylin

    2011-01-01

    Wireless systems comprised of rechargeable nodes have a significantly prolonged lifetime and are sustainable. A distinct characteristic of these systems is the fact that the nodes can harvest energy throughout the duration in which communication takes place. As such, transmission policies of the nodes need to adapt to these harvested energy arrivals. In this paper, we consider optimization of point-to-point data transmission with an energy harvesting transmitter which has a limited battery capacity, communicating in a wireless fading channel. We consider two objectives: maximizing the throughput by a deadline, and minimizing the transmission completion time of the communication session. We optimize these objectives by controlling the time sequence of transmit powers subject to energy storage capacity and causality constraints. We, first, study optimal offline policies. We introduce a directional water-filling algorithm which provides a simple and concise interpretation of the necessary optimality conditions. ...

  7. Optimal investment policy and dividend payment strategy in an insurance company

    OpenAIRE

    Pablo Azcue; Nora Muler

    2010-01-01

    We consider in this paper the optimal dividend problem for an insurance company whose uncontrolled reserve process evolves as a classical Cram\\'{e}r--Lundberg process. The firm has the option of investing part of the surplus in a Black--Scholes financial market. The objective is to find a strategy consisting of both investment and dividend payment policies which maximizes the cumulative expected discounted dividend pay-outs until the time of bankruptcy. We show that the optimal value function...

  8. Optimal Control Policies of Pests for Hybrid Dynamical Systems

    Directory of Open Access Journals (Sweden)

    Baolin Kang

    2013-01-01

    Full Text Available We improve the traditional integrated pest management (IPM control strategies and formulate three specific management strategies, which can be described by hybrid dynamical systems. These strategies can not only effectively control pests but also reduce the abuse of pesticides and protect the natural enemies. The aim of this work is to study how the factors, such as natural enemies optimum choice in the two kinds of different pests, timings of natural enemy releases, dosages and timings of insecticide applications, and instantaneous killing rates of pesticides on both pests and natural enemies, can affect the success of IPM control programmes. The results indicate that the pests outbreak period or frequency largely depends on the optimal selective feeding of the natural enemy between one of the pests and the control tactics. Ultimately, we obtain the only pest needs to be controlled below a certain threshold while not supervising pest .

  9. A new computer method to optimize turbine design and runner replacement

    Energy Technology Data Exchange (ETDEWEB)

    Goede, E.; Cuenod, R.; Grunder, R.; Pestalozzi, J. (Sulzer Escher Wyss, Zurich (Switzerland))

    1991-02-01

    When a designer's ideas for the design or rehabilitation of a hydraulic turbine are tested before the actual machine is manufactured, operating characteristics can be improved. A variety of techniques exist to perform this preliminary design testing. In recent years, great progress has been made in the area of numerical simulation of physical phenomena. Sulzer Escher Wyss has been successfully using the computer method of numerical flow simulation to test designers' ideas. The method calculates the fluid flow in a hydraulic turbomachine, effectively simulating the hydraulic performance of a turbine before it is manufactured. The authors have used flow analysis as a theoretical tool -- a numerical test stand -- to aid in the first cut of turbomachinery design and rehabilitation. This way, only the fine tuning must be made in physical tests. This approach provides a fast and cost-effective layout procedure for machine components. However, the reliability of such a numerical test greatly depends on the quality of the method used, as well as on its proper use in terms of correct boundary conditions and accurate interpretation of the results. To aid in interpretation of the data from the flow analysis, the authors have developed a procedure to compress data from the flow calculations and present them in the form of sophisticated computer graphics. In this way, the design engineer can visualize the main relationships, which will aid him or her in making sound decisions regarding the turbine layout procedure. Ultimately, the method has helped optimize the design and rehabilitation of hydraulic machines, while reducing overall time and expense.

  10. The Optimal Price Policy of Congener Software Product

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    From the viewpoint of market behavior to a certain softwaredevelopment company, it's very important to decide the suitable price to deploy its product. Especially face to the opponents who sale the congener product in the current market. According to the requirement of market economy and software engineering , accurate estimation of software price and its amount of sales are useful to a certain software provider to build a proper development project and software pro ducts' target parameters. Here we analysis the factors which affect the price of the congener software product in the same market, and calculate the weight of t hese factors to it's price on the current market. With the help of principles of the non-cooperative games, we built a model base on AHP methods. Use this model , we can get the optimal price to release our software product and the biggest turnover. At the end of this paper, we use a numerical example to explain how to use our model

  11. Research influence on antimalarial drug policy change in Tanzania: case study of replacing chloroquine with sulfadoxine-pyrimethamine as the first-line drug

    Directory of Open Access Journals (Sweden)

    Gonzalez-Block Miguel A

    2005-10-01

    Full Text Available Abstract Introduction Research is an essential tool in facing the challenges of scaling up interventions and improving access to services. As in many other countries, the translation of research evidence into drug policy action in Tanzania is often constrained by poor communication between researchers and policy decision-makers, individual perceptions or attitudes towards the drug and hesitation by some policy decision-makers to approve change when they anticipate possible undesirable repercussions should the policy change as proposed. Internationally, literature on the role of researchers on national antimalarial drug policy change is limited. Objectives To describe the (a role of researchers in producing evidence that influenced the Tanzanian government replace chloroquine (CQ with sulfadoxine-pyrimethamine (SP as the first-line drug and the challenges faced in convincing policy-makers, general practitioners, pharmaceutical industry and the general public on the need for change (b challenges ahead before a new drug combination treatment policy is introduced in Tanzania. Methods In-depth interviews were held with national-level policy-makers, malaria control programme managers, pharmaceutical officers, general medical practitioners, medical research library and publications officers, university academicians, heads of medical research institutions and district and regional medical officers. Additional data were obtained through a review of malaria drug policy documents and participant observations were also done. Results In year 2001, the Tanzanian Government officially changed its malaria treatment policy guidelines whereby CQ – the first-line drug for a long time was replaced with SP. This policy decision was supported by research evidence indicating parasite resistance to CQ and clinical CQ treatment failure rates to have reached intolerable levels as compared to SP and amodiaquine (AQ. Research also indicated that since SP was also facing

  12. Research influence on antimalarial drug policy change in Tanzania: case study of replacing chloroquine with sulfadoxine-pyrimethamine as the first-line drug.

    Science.gov (United States)

    Mubyazi, Godfrey M; Gonzalez-Block, Miguel A

    2005-10-20

    Research is an essential tool in facing the challenges of scaling up interventions and improving access to services. As in many other countries, the translation of research evidence into drug policy action in Tanzania is often constrained by poor communication between researchers and policy decision-makers, individual perceptions or attitudes towards the drug and hesitation by some policy decision-makers to approve change when they anticipate possible undesirable repercussions should the policy change as proposed. Internationally, literature on the role of researchers on national antimalarial drug policy change is limited. To describe the (a) role of researchers in producing evidence that influenced the Tanzanian government replace chloroquine (CQ) with sulfadoxine-pyrimethamine (SP) as the first-line drug and the challenges faced in convincing policy-makers, general practitioners, pharmaceutical industry and the general public on the need for change (b) challenges ahead before a new drug combination treatment policy is introduced in Tanzania. In-depth interviews were held with national-level policy-makers, malaria control programme managers, pharmaceutical officers, general medical practitioners, medical research library and publications officers, university academicians, heads of medical research institutions and district and regional medical officers. Additional data were obtained through a review of malaria drug policy documents and participant observations were also done. In year 2001, the Tanzanian Government officially changed its malaria treatment policy guidelines whereby CQ--the first-line drug for a long time was replaced with SP. This policy decision was supported by research evidence indicating parasite resistance to CQ and clinical CQ treatment failure rates to have reached intolerable levels as compared to SP and amodiaquine (AQ). Research also indicated that since SP was also facing rising resistance trend, the need for a more effective drug was

  13. AN OPTIMAL REPLENISHMENT POLICY FOR DETERIORATING ITEMS WITH RAMP TYPE DEMAND UNDER PERMISSIBLE DELAY IN PAYMENTS

    Directory of Open Access Journals (Sweden)

    Dr. Sanjay Jain

    2010-10-01

    Full Text Available The aim of this paper is to develop an optimal replenishment policy for inventory models of deteriorating items with ramp type demand under permissible delay in payments. Deterioration of items begins on their arrival in stock.  An example is also presented to illustrate the application of developed model.

  14. A policy iteration approach to online optimal control of continuous-time constrained-input systems.

    Science.gov (United States)

    Modares, Hamidreza; Naghibi Sistani, Mohammad-Bagher; Lewis, Frank L

    2013-09-01

    This paper is an effort towards developing an online learning algorithm to find the optimal control solution for continuous-time (CT) systems subject to input constraints. The proposed method is based on the policy iteration (PI) technique which has recently evolved as a major technique for solving optimal control problems. Although a number of online PI algorithms have been developed for CT systems, none of them take into account the input constraints caused by actuator saturation. In practice, however, ignoring these constraints leads to performance degradation or even system instability. In this paper, to deal with the input constraints, a suitable nonquadratic functional is employed to encode the constraints into the optimization formulation. Then, the proposed PI algorithm is implemented on an actor-critic structure to solve the Hamilton-Jacobi-Bellman (HJB) equation associated with this nonquadratic cost functional in an online fashion. That is, two coupled neural network (NN) approximators, namely an actor and a critic are tuned online and simultaneously for approximating the associated HJB solution and computing the optimal control policy. The critic is used to evaluate the cost associated with the current policy, while the actor is used to find an improved policy based on information provided by the critic. Convergence to a close approximation of the HJB solution as well as stability of the proposed feedback control law are shown. Simulation results of the proposed method on a nonlinear CT system illustrate the effectiveness of the proposed approach. Copyright © 2013 ISA. All rights reserved.

  15. Seawater intrusion policy analysis with a numerical spatially heterogeneous dynamic optimization model

    Science.gov (United States)

    Reinelt, Peter

    2005-05-01

    For more than 50 years, Monterey County and California State officials have pursued without success water policies to halt groundwater overdraft and seawater intrusion in the multilayer confined aquifers underlying arguably the most productive farmland in the United States. This study develops a general dynamic optimization model that emphasizes the institutional and physical characteristics that differentiate this policy problem from other groundwater extraction problems. The solution of the model exhibits heterogeneous spatial distribution of optimal extraction based on spatially distributed extraction cost, pumping cost externality, and seawater intrusion stock externality. Comparison of model results under alternative management regimes elucidates landowner economic incentives, reveals the potential welfare loss of current state policy, and explains much of the history of the political economy of water in Monterey County.

  16. Optimal Inventory Policy under Permissible Payment Delay in Fashion Supply Chains

    Directory of Open Access Journals (Sweden)

    Guo Li

    2014-01-01

    Full Text Available This paper investigates a retailer’s optimal inventory cycle and the corresponding time of payment in fashion supply chains where a supplier allows the payment delay. Here according to the established model we first analyze the retailer's reaction, and then find out the retailer’s optimal inventory policy and time of payment to maximize its total profit. Our result shows that it is not always the best choice for retailers of fashion supply chains to choose the discount way to replenish stocks, but the retailer can decide the optimal credit period and inventory cycle. Moreover, numerical examples are provided to illustrate the model’s feasibility and rationality.

  17. Social Optimization and Pricing Policy in Cognitive Radio Networks with an Energy Saving Strategy

    Directory of Open Access Journals (Sweden)

    Shunfu Jin

    2016-01-01

    Full Text Available The rapid growth of wireless application results in an increase in demand for spectrum resource and communication energy. In this paper, we firstly introduce a novel energy saving strategy in cognitive radio networks (CRNs and then propose an appropriate pricing policy for secondary user (SU packets. We analyze the behavior of data packets in a discrete-time single-server priority queue under multiple-vacation discipline. With the help of a Quasi-Birth-Death (QBD process model, we obtain the joint distribution for the number of SU packets and the state of base station (BS via the Matrix-Geometric Solution method. We assess the average latency of SU packets and the energy saving ratio of system. According to a natural reward-cost structure, we study the individually optimal behavior and the socially optimal behavior of the energy saving strategy and use an optimization algorithm based on standard particle swarm optimization (SPSO method to search the socially optimal arrival rate of SU packets. By comparing the individually optimal behavior and the socially optimal behavior, we impose an appropriate admission fee to SU packets. Finally, we present numerical results to show the impacts of system parameters on the system performance and the pricing policy.

  18. Loss-Averse Retailer’s Optimal Ordering Policies for Perishable Products with Customer Returns

    Directory of Open Access Journals (Sweden)

    Xu Chen

    2014-01-01

    Full Text Available We investigate the loss-averse retailer’s ordering policies for perishable product with customer returns. With the introduction of the segmental loss utility function, we depict the retailer’s loss aversion decision bias and establish the loss-averse retailer’s ordering policy model. We derive that the loss-averse retailer’s optimal order quantity with customer returns exists and is unique. By comparison, we obtain that both the risk-neutral and the loss-averse retailer’s optimal order quantities depend on the inventory holding cost and the marginal shortage cost. Through the sensitivity analysis, we also discuss the effect of loss-averse coefficient and the ratio of return on the loss-averse retailer’s optimal order quantity with customer returns.

  19. Suported by Replacement Policy for Caching World-Wide Web Documents Based on Site-Graph Model

    Institute of Scientific and Technical Information of China (English)

    庄伟强; 胡敏; 王鼎兴; 郑纬民; 沈美明

    2001-01-01

    The hit rate, a major metric for evaluating proxy caches, is mostly limited by the replacementstrategy of proxy caches. However, in traditional proxy caches, the hit rate does not usually successfullypredict how well a proxy cache will perform because the proxy cache counts any hit in its caching space whichhas many pages without useful information, so its replacement strategy fails to determine which pages to keepand which to release. The proxy cache efficiency can be measured more accurately using the valid hit rateintroduced in this paper. An efficient replacement strategy based on the Site-Graph model for WWW(World-Wide Web) documents is also discussed in this paper. The model analyzes user access behavior as abasis for the replacement strategy. Simulation results demonstrate that the replacement strategy improvesproxy cache efficiency.``

  20. Replacing penalties

    Directory of Open Access Journals (Sweden)

    Vitaly Stepashin

    2017-01-01

    Full Text Available УДК 343.24The subject. The article deals with the problem of the use of "substitute" penalties.The purpose of the article is to identify criminal and legal criteria for: selecting the replacement punishment; proportionality replacement leave punishment to others (the formalization of replacement; actually increasing the punishment (worsening of legal situation of the convicted.Methodology.The author uses the method of analysis and synthesis, formal legal method.Results. Replacing the punishment more severe as a result of malicious evasion from serving accused designated penalty requires the optimization of the following areas: 1 the selection of a substitute punishment; 2 replacement of proportionality is serving a sentence other (formalization of replacement; 3 ensuring the actual toughening penalties (deterioration of the legal status of the convict. It is important that the first two requirements pro-vide savings of repression in the implementation of the replacement of one form of punishment to others.Replacement of punishment on their own do not have any specifics. However, it is necessary to compare them with the contents of the punishment, which the convict from serving maliciously evaded. First, substitute the punishment should assume a more significant range of restrictions and deprivation of certain rights of the convict. Second, the perfor-mance characteristics of order substitute the punishment should assume guarantee imple-mentation of the new measures.With regard to replacing all forms of punishment are set significant limitations in the application that, in some cases, eliminates the possibility of replacement of the sentence, from serving where there has been willful evasion, a stricter measure of state coercion. It is important in the context of the topic and the possibility of a sentence of imprisonment as a substitute punishment in cases where the original purpose of the strict measures excluded. It is noteworthy that the

  1. An optimal inventory policy under certainty distributed demand for cutting tools with stochastically distributed lifespan

    Directory of Open Access Journals (Sweden)

    Cun Rong Li

    2015-12-01

    Full Text Available Traditional inventory policy was deeply investigated for various kinds of demand in different industrial sectors. More extensive explorations on inventory policy, including the combination with manufacturing process, detailed attributes of the purchased products, etc. was conducted by many researchers. During manufacturing process, lifespan of cutting tools have significant impact on both the quantity of inventory and production cost. In this paper, the impact of maximum allowable stopping time for cutting tools on production-inventory policy under general production demands was investigated. An optimal inventory policy with general demand (OIPGD was developed with which the allowable stopping time for tools, order-up-to-level inventory, and order cycle can be optimally determined by an exhaustive searching algorithm. Examples with different distributions on tool lifespan and production demand is presented to show the implementation of the OIPGD model. The results and the sensitivity analysis about the parameters show that optimized combination of selection for tool allowable stopping time, order-up-to-level, and order cycle time can dramatically minimize the total cost of the whole inventory activity.

  2. Control of parallel non-observable queues: Asymptotic equivalence and optimality of periodic policies

    Directory of Open Access Journals (Sweden)

    Jonatha Anselmi

    2015-12-01

    Full Text Available We consider a queueing system composed of a dispatcher that routes jobs to a set of non-observable queues working in parallel. In this setting, the fundamental problem is which policy should the dispatcher implement to minimize the stationary mean waiting time of the incoming jobs. We present a structural property that holds in the classic scaling of the system where the network demand (arrival rate of jobs grows proportionally with the number of queues. Assuming that each queue of type r is replicated k times, we consider a set of policies that are periodic with period k∑rpr and such that exactly pr jobs are sent in a period to each queue of type r. When k→∞, our main result shows that all the policies in this set are equivalent, in the sense that they yield the same mean stationary waiting time, and optimal, in the sense that no other policy having the same aggregate arrival rate to all queues of a given type can do better in minimizing the stationary mean waiting time. This property holds in a strong probabilistic sense. Furthermore, the limiting mean waiting time achieved by our policies is a convex function of the arrival rate in each queue, which facilitates the development of a further optimization aimed at solving the fundamental problem above for large systems.

  3. Joint Optimal Production Planning for Complex Supply Chains Constrained by Carbon Emission Abatement Policies

    Directory of Open Access Journals (Sweden)

    Longfei He

    2014-01-01

    Full Text Available We focus on the joint production planning of complex supply chains facing stochastic demands and being constrained by carbon emission reduction policies. We pick two typical carbon emission reduction policies to research how emission regulation influences the profit and carbon footprint of a typical supply chain. We use the input-output model to capture the interrelated demand link between an arbitrary pair of two nodes in scenarios without or with carbon emission constraints. We design optimization algorithm to obtain joint optimal production quantities combination for maximizing overall profit under regulatory policies, respectively. Furthermore, numerical studies by featuring exponentially distributed demand compare systemwide performances in various scenarios. We build the “carbon emission elasticity of profit (CEEP” index as a metric to evaluate the impact of regulatory policies on both chainwide emissions and profit. Our results manifest that by facilitating the mandatory emission cap in proper installation within the network one can balance well effective emission reduction and associated acceptable profit loss. The outcome that CEEP index when implementing Carbon emission tax is elastic implies that the scale of profit loss is greater than that of emission reduction, which shows that this policy is less effective than mandatory cap from industry standpoint at least.

  4. Optimal air quality policies and health: a multi-objective nonlinear approach.

    Science.gov (United States)

    Relvas, Helder; Miranda, Ana Isabel; Carnevale, Claudio; Maffeis, Giuseppe; Turrini, Enrico; Volta, Marialuisa

    2017-05-01

    The use of modelling tools to support decision-makers to plan air quality policies is now quite widespread in Europe. In this paper, the Regional Integrated Assessment Tool (RIAT+), which was designed to support policy-maker decision on optimal emission reduction measures to improve air quality at minimum costs, is applied to the Porto Urban Area (Portugal). In addition to technological measures, some local measures were included in the optimization process. Case study results are presented for a multi-objective approach focused on both NO2 and PM10 control measures, assuming equivalent importance in the optimization process. The optimal set of air quality measures is capable to reduce simultaneously the annual average concentrations values of PM10 and NO2 in 1.7 and 1.0 μg/m(3), respectively. This paper illustrates how the tool could be used to prioritize policy objectives and help making informed decisions about reducing air pollution and improving public health.

  5. Structure and Optimality of Myopic Policy in Opportunistic Access with Noisy Observations

    CERN Document Server

    Zhao, Qing

    2008-01-01

    A restless multi-armed bandit problem that arises in multichannel opportunistic communications is considered, where channels are modeled as independent and identical Gilbert-Elliot channels and channel state observations are subject to errors. A simple structure of the myopic policy is established under a certain condition on the false alarm probability of the channel state detector. It is shown that myopic actions can be obtained with a simple counting procedure without knowing the underlying Markovian model. The optimality of the myopic policy is proved for the case of two channels and conjectured based on simulations for the general case.

  6. Policy Iteration for H∞ Optimal Control of Polynomial Nonlinear Systems via Sum of Squares Programming.

    Science.gov (United States)

    Zhu, Yuanheng; Zhao, Dongbin; Yang, Xiong; Zhang, Qichao

    2017-01-10

    Sum of squares (SOS) polynomials have provided a computationally tractable way to deal with inequality constraints appearing in many control problems. It can also act as an approximator in the framework of adaptive dynamic programming. In this paper, an approximate solution to the H∞ optimal control of polynomial nonlinear systems is proposed. Under a given attenuation coefficient, the Hamilton-Jacobi-Isaacs equation is relaxed to an optimization problem with a set of inequalities. After applying the policy iteration technique and constraining inequalities to SOS, the optimization problem is divided into a sequence of feasible semidefinite programming problems. With the converged solution, the attenuation coefficient is further minimized to a lower value. After iterations, approximate solutions to the smallest L₂-gain and the associated H∞ optimal controller are obtained. Four examples are employed to verify the effectiveness of the proposed algorithm.

  7. Joint Optimization of Preventive Maintenance and Spare Parts Inventory with Appointment Policy

    Directory of Open Access Journals (Sweden)

    Jing Cai

    2017-01-01

    Full Text Available Under the background of the wide application of condition-based maintenance (CBM in maintenance practice, the joint optimization of maintenance and spare parts inventory is becoming a hot research to take full advantage of CBM and reduce the operational cost. In order to avoid both the high inventory level and the shortage of spare parts, an appointment policy of spare parts is first proposed based on the prediction of remaining useful lifetime, and then a corresponding joint optimization model of preventive maintenance and spare parts inventory is established. Due to the complexity of the model, the combination method of genetic algorithm and Monte Carlo is presented to get the optimal maximum inventory level, safety inventory level, potential failure threshold, and appointment threshold to minimize the cost rate. Finally, the proposed model is studied through a case study and compared with both the separate optimization and the joint optimization without appointment policy, and the results show that the proposed model is more effective. In addition, the sensitivity analysis shows that the proposed model is consistent with the actual situation of maintenance practices and inventory management.

  8. Optimal replenishment policy for fuzzy inventory model with deteriorating items and allowable shortages under inflationary conditions

    Directory of Open Access Journals (Sweden)

    Jaggi Chandra K.

    2016-01-01

    Full Text Available This study develops an inventory model to determine ordering policy for deteriorating items with constant demand rate under inflationary condition over a fixed planning horizon. Shortages are allowed and are partially backlogged. In today’s wobbling economy, especially for long term investment, the effects of inflation cannot be disregarded as uncertainty about future inflation may influence the ordering policy. Therefore, in this paper a fuzzy model is developed that fuzzify the inflation rate, discount rate, deterioration rate, and backlogging parameter by using triangular fuzzy numbers to represent the uncertainty. For Defuzzification, the well known signed distance method is employed to find the total profit over the planning horizon. The objective of the study is to derive the optimal number of cycles and their optimal length so to maximize the net present value of the total profit over a fixed planning horizon. The necessary and sufficient conditions for an optimal solution are characterized. An algorithm is proposed to find the optimal solution. Finally, the proposed model has been validated with numerical example. Sensitivity analysis has been performed to study the impact of various parameters on the optimal solution, and some important managerial implications are presented.

  9. Optimal Inventory Policy under Permissible Payment Delay in Fashion Supply Chains

    OpenAIRE

    Guo Li; Yuchen Kang; Mengqi Liu; Zhaohua Wang

    2014-01-01

    This paper investigates a retailer’s optimal inventory cycle and the corresponding time of payment in fashion supply chains where a supplier allows the payment delay. Here according to the established model we first analyze the retailer's reaction, and then find out the retailer’s optimal inventory policy and time of payment to maximize its total profit. Our result shows that it is not always the best choice for retailers of fashion supply chains to choose the discount way to replenish stocks...

  10. Optimal Exchange Rate Policy:The Influence of Price-Setting and Asset Markets

    OpenAIRE

    Charles Engel

    2000-01-01

    This paper examines optimal exchange-rate policy in two-country sticky-price general equilibrium models in which households and firms optimize over an infinite horizon in an environment of uncertainty. The models are in the vein of the new open-economy macroeconomics' as exemplified by Obstfeld and Rogoff (1995, 1998, 2000). The conditions under which fixed or floating exchange rates yield higher welfare depend on the exact nature of price stickiness and on the degree of risk-sharing opportun...

  11. Optimal ordering and production policy for a recoverable item inventory system with learning effect

    Science.gov (United States)

    Tsai, Deng-Maw

    2012-02-01

    This article presents two models for determining an optimal integrated economic order quantity and economic production quantity policy in a recoverable manufacturing environment. The models assume that the unit production time of the recovery process decreases with the increase in total units produced as a result of learning. A fixed proportion of used products are collected from customers and then recovered for reuse. The recovered products are assumed to be in good condition and acceptable to customers. Constant demand can be satisfied by utilising both newly purchased products and recovered products. The aim of this article is to show how to minimise total inventory-related cost. The total cost functions of the two models are derived and two simple search procedures are proposed to determine optimal policy parameters. Numerical examples are provided to illustrate the proposed models. In addition, sensitivity analyses have also been performed and are discussed.

  12. Optimal production policy for a remanufacturing system with virtual inventory cost

    Science.gov (United States)

    Nakashima, Kenichi; Gupta, Surendra M.

    2005-11-01

    This paper deals with a cost management problem of a remanufacturing system with stochastic demand. We model the system with consideration for two types of inventories. One is the actual product inventory in the factory. The other is the virtual inventory that is being used by the customer. For this virtual inventory, it should be required to consider an operational cost that we need in order to observe and check the quantity of the inventory. We call this the virtual inventory cost and model the system by including it. We define the state of the remanufacturing system by the two inventory levels. It is assumed that the cost function is composed of various cost factors such as holding, backlog and manufacturing costs. We obtain the optimal policy that minimizes the expected average cost per period. Numerical results reveal the effects of the factors on the optimal policy.

  13. A Simulation Optimization Algorithm for CTMDPs Based on Randomized Stationary Policies1)

    Institute of Scientific and Technical Information of China (English)

    TANGHao; XIHong-Sheng; YINBao-Qun

    2004-01-01

    Based on the theory of Markov performance potentials and neuro-dynamic programming(NDP) methodology, we study simulation optimization algorithm for a class of continuous timeMarkov decision processes (CTMDPs) under randomized stationary policies. The proposed algo-rithm will estimate the gradient of average cost performance measure with respect to policy param-eters by transforming a continuous time Markov process into a uniform Markov chain and simula-ting a single sample path of the chain. The goal is to look for a suboptimal randomized stationarypolicy. The algorithm derived here can meet the needs of performance optimization of many diffi-cult systems with large-scale state space. Finally, a numerical example for a controlled Markovprocess is provided.

  14. Optimal Monetary Policy and Exchange Rate in a Small Open Economy with Unemployment

    Directory of Open Access Journals (Sweden)

    Hyuk-Jae Rhee

    2014-09-01

    Full Text Available In this paper, we consider a small open economy under the New Keynesian model with unemployment of Gali (2011a, b to discuss the design of the monetary policy. Our findings can be summarized in three parts. First, even with the existence of unemployment, the optimal policy is to minimize variance of domestic price inflation, wage inflation, and the output gap when both domestic price and wage are sticky. Second, stabilizing unemployment rate is important in reducing the welfare loss incurred by both technology and labor supply shocks. Therefore, introducing the unemployment rate as an another argument into the Taylor-rule type interest rate rule will be welfare-enhancing. Lastly, controlling CPI inflation is the best option when the policy is not allowed to respond to unemployment rate. Once the unemployment rate is controlled, however, stabilizing power of CPI inflation-based Taylor rule is diminished.

  15. Geometric-Process-Based Battery Management Optimizing Policy for the Electric Bus

    Directory of Open Access Journals (Sweden)

    Yan Li

    2015-01-01

    Full Text Available With the rapid development of the electric vehicle industry and promotive policies worldwide, the electric bus (E-bus has been adopted in many major cities around the world. One of the most important factors that restrain the widespread application of the E-bus is the high operating cost due to the deficient battery management. This paper proposes a geometric-process-based (GP-based battery management optimizing policy which aims to minimize the average cost of the operation on the premise of meeting the required sufficient battery availability. Considering the deterioration of the battery after repeated charging and discharging, this paper constructs the model of the operation of the E-bus battery as a geometric process, and the premaintenance time has been considered with the failure repairment time to enhance the GP-based battery operation model considering the battery cannot be as good as new after the two processes. The computer simulation is carried out by adopting the proposed optimizing policy, and the result verifies the effectiveness of the policy, denoting its significant performance on the application of the E-bus battery management.

  16. Optimal vaccine schedules to maintain measles elimination with a two-dose routine policy.

    Science.gov (United States)

    McKEE, A; Shea, K; Ferrari, M J

    2017-01-01

    Measles was eliminated in the Americas in 2002 by a combination of routine immunizations and supplementary immunization activities. Recent outbreaks underscore the importance of reconsidering vaccine policy in order to maintain elimination. We constructed an age-structured dynamical model for the distribution of immunity in a population with routine immunization and without disease, and analysed the steady state for an idealized age structure and for real age structures of countries in the Americas. We compared the level of immunity maintained by current policy in these countries to the level maintainable by an optimal policy. The optimal age target for the first routine dose of measles vaccine depends on the timing and coverage of both doses. Similarly, the optimal age target for the second dose of measles vaccine depends on the timing and coverage of the first dose. The age targets for the first and second doses of measles vaccine should be adjusted for the post-elimination era, by specifically accounting for current context, including realized coverage of both doses, and altered maternal immunity. Doing so can greatly improve the proportion immune within a population, and therefore the chances of maintaining measles elimination, without changing coverage.

  17. An optimal policy based on the genetic algorithm for the dynamic threshold of the optical network

    Science.gov (United States)

    Zhu, Hongying; Le, Zichun; Dong, Wen; Fu, Minglei

    2006-09-01

    The complete partitioning policy (CP) for the wavelength resource in optical networks is now widely focused on. The dynamic threshold is one of the ways to make CP policy more efficient. Furthermore, an optimized threshold will be better for reducing the blocking probability and improving the utilization of the wavelength resource. Hence, the genetic algorithm is selected as the optimal policy on virtue of its excellent global search performance for getting optimized value of the dynamic threshold. Moreover, a maximal threshold as the high limit for the dynamic threshold is needed to be decided for making wavelengths shared between different wavelength classes, because the class with higher priority can share its wavelengths with the lower one after its own call setups are satisfied. Therefore, a neural network predictor that can predict the number of the next call setup is designed on the basis of the genetic algorithm to solve this problem. The values of the dynamic threshold and the maximal threshold are calculated, and the simulation results show that they take good effect in reducing the blocking probability and improving the utilization of the wavelength resource.

  18. Pharmacogenetics of glucocorticoid replacement could optimize the treatment of congenital adrenal hyperplasia due to 21-hydroxylase deficiency

    Directory of Open Access Journals (Sweden)

    Ricardo P. P. Moreira

    2011-01-01

    Full Text Available INTRODUCTION: 21-hydroxylase deficiency is an autosomal recessive disorder that causes glucocorticoid deficiency and increased androgen production. Treatment is based on glucocorticoid replacement; however, interindividual variability in the glucocorticoid dose required to achieve adequate hormonal control has been observed. OBJECTIVE: The present study aimed to evaluate the association between polymorphic variants involved inglucocorticoid action and/or metabolism and the mean daily glucocorticoid dose in 21-hydroxylase deficiency patients. METHODS: We evaluated 53 patients with classical forms of 21-hydroxylase deficiency who were receiving cortisone acetate. All patients were between four and six years of age and had normal androgen levels. RESULTS: The P450 oxidoreductase A503V, HSD11B1 rs12086634, and CYP3A7*1C variants were found in 19%, 11.3% and 3.8% of the patients, respectively. The mean ± SD glucocorticoid dose in patients with the CYP3A7*1C and wild-type alleles was 13.9 ± 0.8 and 19.5 ± 3.2 mg/m²/d, respectively. We did not identify an association between the P450 oxidoreductase or HSD11B1 allelic variants and the mean glucocorticoid dose. CONCLUSION: Patients carrying the CYP3A7*1C variant required a significantly lower mean glucocorticoid dose. Indeed, the CYP3A7*1C allele accounted for 20% of the variability in the cortisone acetate dose. The analysis of genes involved in glucocorticoid metabolism may be useful in the optimization of treatment of 21-hydroxylase deficiency.

  19. Optimal pricing and promotional effort control policies for a new product growth in segmented market

    Directory of Open Access Journals (Sweden)

    Jha P.C.

    2015-01-01

    Full Text Available Market segmentation enables the marketers to understand and serve the customers more effectively thereby improving company’s competitive position. In this paper, we study the impact of price and promotion efforts on evolution of sales intensity in segmented market to obtain the optimal price and promotion effort policies. Evolution of sales rate for each segment is developed under the assumption that marketer may choose both differentiated as well as mass market promotion effort to influence the uncaptured market potential. An optimal control model is formulated and a solution method using Maximum Principle has been discussed. The model is extended to incorporate budget constraint. Model applicability is illustrated by a numerical example. P.C. Jha, P. Manik, K. Chaudhary, R. Cambini / Optimal Pricing and Promotional 2 Since the discrete time data is available, the formulated model is discretized. For solving the discrete model, differential evolution algorithm is used.

  20. Optimal control policies for carbon dioxide miscible flooding enhanced oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Methos, G.J.

    1986-01-01

    Optimal control theory of distributed parameter systems has been used to develop improved operational strategies for carbon dioxide miscible flooding. The optimization criterion was to maximize the net profitability of the CO/sub 2/ flood. A two-dimensional, three-phase, modified black-oil model was used to describe miscible displacement of oil. Calculus of variations was applied to find control functions that provide extreme for an objective functional which related injection costs and production revenue. Lagrange multipliers, or costate variables, were used to ensure that the constraints given by the equations of the simulation model were satisfied. Control functions computed were the carbon dioxide and water injection policies and the production wellbore pressure history. In order to avoid difficulties in obtaining a stable numerical scheme for the costate equation, a discrete formulation of the optimal control problem was developed. A steepest decent gradient search method was used to find the optimal control law. Starting functions for the algorithm described currently used strategies: a large slug of CO/sub 2/ followed by drive water; carbon dioxide injected simultaneously with water; and injection of small slugs of CO/sub 2/ alternately with slugs of water. Improvements in the cost functional from the starting functions ranged from four to eleven percent. While the optimal control law found was highly dependent upon the starting functions used to initiate the algorithm, the shape of the optimal control law was found to be unique, as was the optimal total volume of carbon dioxide injected and the optimal value of the cost functional.

  1. Computation of a near-optimal service policy for a single-server queue with homogeneous jobs

    DEFF Research Database (Denmark)

    Johansen, Søren Glud; Larsen, Christian

    2001-01-01

    We present an algorithm for computing a near-optimal service policy for a single-server queueing system when the service cost is a convex function of the service time. The policy has state-dependent service times, and it includes the options to remove jobs from the system and to let the server...

  2. Computation of a near-optimal service policy for a single-server queue with homogeneous jobs

    DEFF Research Database (Denmark)

    Johansen, Søren Glud; Larsen, Christian

    2000-01-01

    We present an algorithm for computing a near optimal service policy for a single-server queueing system when the service cost is a convex function of the service time. The policy has state-dependent service times, and it includes the options to remove jobs from the system and to let the server...

  3. Off-policy integral reinforcement learning optimal tracking control for continuous-time chaotic systems

    Science.gov (United States)

    Wei, Qing-Lai; Song, Rui-Zhuo; Sun, Qiu-Ye; Xiao, Wen-Dong

    2015-09-01

    This paper estimates an off-policy integral reinforcement learning (IRL) algorithm to obtain the optimal tracking control of unknown chaotic systems. Off-policy IRL can learn the solution of the HJB equation from the system data generated by an arbitrary control. Moreover, off-policy IRL can be regarded as a direct learning method, which avoids the identification of system dynamics. In this paper, the performance index function is first given based on the system tracking error and control error. For solving the Hamilton-Jacobi-Bellman (HJB) equation, an off-policy IRL algorithm is proposed. It is proven that the iterative control makes the tracking error system asymptotically stable, and the iterative performance index function is convergent. Simulation study demonstrates the effectiveness of the developed tracking control method. Project supported by the National Natural Science Foundation of China (Grant Nos. 61304079 and 61374105), the Beijing Natural Science Foundation, China (Grant Nos. 4132078 and 4143065), the China Postdoctoral Science Foundation (Grant No. 2013M530527), the Fundamental Research Funds for the Central Universities, China (Grant No. FRF-TP-14-119A2), and the Open Research Project from State Key Laboratory of Management and Control for Complex Systems, China (Grant No. 20150104).

  4. Optimal (r, nQ, T) batch-ordering policy under stationary demand

    Science.gov (United States)

    Lagodimos, A. G.; Christou, I. T.; Skouri, K.

    2012-09-01

    We consider the control of a single-echelon inventory system under the standard ? batch-ordering policy. Demand follows a stationary stochastic process and, when unsatisfied, is backordered. Under a standard cost structure, we seek to minimise total average cost per unit time. In contrast to previous research, all three policy variables (i.e. reorder level r, batch size Q and review interval T) are simultaneously optimised. While average total cost is not convex, analytic properties for two new cost bounds and a Newsboy characterisation of the optimal solution lead to an exact search algorithm with guaranteed convergence to the global optimum. Computational results demonstrate that the inclusion of the review interval as a decision variable in the optimisation problem can offer substantial cost savings.

  5. Optimal ordering and pricing policy for price sensitive stock–dependent demand under progressive payment scheme

    Directory of Open Access Journals (Sweden)

    Nita H. Shah

    2011-01-01

    Full Text Available The terminal condition of inventory level to be zero at the end of the cycle time adopted by Soni and Shah (2008, 2009 is not viable when demand is stock-dependent. To rectify this assumption, we extend their model for (1 an ending – inventory to be non-zero; (2 limited floor space; (3 a profit maximization model; (4 selling price to be a decision variable, and (5 units in inventory deteriorate at a constant rate. The algorithm is developed to search for the optimal decision policy. The working of the proposed model is supported with a numerical example. Sensitivity analysis is carried out to investigate critical parameters.

  6. Optimal Policy for Brownian Inventory Models with General Convex Inventory Cost

    Institute of Scientific and Technical Information of China (English)

    Da-cheng YAO

    2013-01-01

    We study an inventory system in which products are ordered from outside to meet demands,and the cumulative demand is governed by a Brownian motion.Excessive demand is backlogged.We suppose that the shortage and holding costs associated with the inventory are given by a general convex function.The product ordering from outside incurs a linear ordering cost and a setup fee.There is a constant leadtime when placing an order.The optimal policy is established so as to minimize the discounted cost including the inventory cost and ordering cost.

  7. Optimal dividend policies with transaction costs for a class of jump-diffusion processes

    DEFF Research Database (Denmark)

    Hunting, Martin; Paulsen, Jostein

    2013-01-01

    his paper addresses the problem of finding an optimal dividend policy for a class of jump-diffusion processes. The jump component is a compound Poisson process with negative jumps, and the drift and diffusion components are assumed to satisfy some regularity and growth restrictions. Each dividend...... payment is changed by a fixed and a proportional cost, meaning that if ξ is paid out by the company, the shareholders receive kξ−K, where k and K are positive. The aim is to maximize expected discounted dividends until ruin. It is proved that when the jumps belong to a certain class of light...

  8. Determination of optimal environmental policy for reclamation of land unearthed in lignite mines - Strategy and tactics

    Science.gov (United States)

    Batzias, Dimitris F.; Pollalis, Yannis A.

    2012-12-01

    In this paper, optimal environmental policy for reclamation of land unearthed in lignite mines is defined as a strategic target. The tactics concerning the achievement of this target, includes estimation of optimal time lag between each lignite site (which is a segment of the whole lignite field) complete exploitation and its reclamation. Subsidizing of reclamation has been determined as a function of this time lag and relevant implementation is presented for parameter values valid for the Greek economy. We proved that the methodology we have developed gives reasonable quantitative results within the norms imposed by legislation. Moreover, the interconnection between strategy and tactics becomes evident, since the former causes the latter by deduction and the latter revises the former by induction in the time course of land reclamation.

  9. Nonuniqueness versus Uniqueness of Optimal Policies in Convex Discounted Markov Decision Processes

    Directory of Open Access Journals (Sweden)

    Raúl Montes-de-Oca

    2013-01-01

    Full Text Available From the classical point of view, it is important to determine if in a Markov decision process (MDP, besides their existence, the uniqueness of the optimal policies is guaranteed. It is well known that uniqueness does not always hold in optimization problems (for instance, in linear programming. On the other hand, in such problems it is possible for a slight perturbation of the functional cost to restore the uniqueness. In this paper, it is proved that the value functions of an MDP and its cost perturbed version stay close, under adequate conditions, which in some sense is a priority. We are interested in the stability of Markov decision processes with respect to the perturbations of the cost-as-you-go function.

  10. Optimal inventory policy in a closed loop supply chain system with multiple periods

    Directory of Open Access Journals (Sweden)

    SasiKumar A.

    2017-05-01

    Full Text Available Purpose: This paper aims to model and optimize the closed loop supply chain for maximizing the profit by considering the fixed order quantity inventory policy in various sites at multiple periods. Design/methodology/approach: In forward supply chain, a standard inventory policy can be followed when the product moves from manufacturer, distributer, retailer and customer but the inventory in the reverse supply chain of the product with the similar standard policy is very difficult to manage. This model investigates the standard policy of fixed order quantity by considering the three major types of return-recovery pair such as commercial returns, end- of- use returns, end –of- life returns and their inventory positioning at multiple periods.  The model is configured as mixed integer linear programming and solved by IBM ILOG CPLEX OPL studio. Findings: To find the performance of the model a numerical example is considered for a product with three Parts (A which of 2nos, B and C for 12 multiple periods. The results of the analysis show that the manufacturer can know how much should to be manufacture in multiple periods based on Variations of the demand by adopting the FOQ inventory policy at different sites considering its capacity constraints. In addition, it is important how much of parts should be purchased from the supplier at the given 12 periods. Originality/value: A sensitivity analysis is performed to validate the proposed model two parts. First part of the analysis will focus on the inventory of product and parts and second part of analysis focus on profit of the company. The analysis which provides some insights in to the structure of the model.

  11. OPTIMAL IMPROVEMENT IN FUNCTION AFTER TOTAL HIP AND KNEE REPLACEMENT: HOW DEEP DO YOU KNOW YOUR PATIENT’S MIND?

    Science.gov (United States)

    De Caro, M F; Vicenti, G; Abate, A; Picca, G; Leoncini, V; Lomuscio, M; Casalino, A; Solarino, G; Moretti, B

    2015-01-01

    Osteoarthritis (OA) of the hip and knee causes pain and loss of joint mobility, leading to limitations in physical function. When conservative treatment fails total hip and knee replacement is a cost-effective surgical option. Patients have high expectations regarding functional outcome after these procedures. If such expectations are not met, they may still be dissatisfied with the outcome of a technically successful procedure. Recently, numerous studies reported that psychological factors can influence the outcome of total knee replacement (tkr) and total hip artrhoplasty with total hip replacement (thr). We conducted a prospective study on a consecutive sample of 280 patients affected by hip or knee OA who underwent total joint replacement. At patients’ admission, Harris Hip Score (HHS) and Knee Society Score (KSS) were used to assess pain and function. Furthermore, SF-36, Mini-Mental Status Examination (MMSE), Symptom Checklist-90-R (SCL-90-R), Coping Orientation to Problems Experienced (BRIEF-COPE) and the Amsterdam Preoperative Anxiety and Information Scale (APAIS) were administered. Patients had clinical and radio graphical follow up at 1, 3 and 6 months post-operatively. The HHS and KSS values before surgery showed a linear correlation with both SCL-90-R and MMSE. None of the investigated variables influenced post-operative HHS and KSS scores; however, the improvement of functional scores resulted conditioned by SCL-90-R values, VAS score, schooling and MMSE. Psychological factors and mental status in primary total hip and knee replacement can affect outcome and patient satisfaction. Strategies focused on identification and facing of these conditions must be considered to improve outcome of total replacement.

  12. Experimental study of optimal self compacting concrete with spent foundry sand as partial replacement for M-sand using Taguchi approach

    Science.gov (United States)

    Nirmala, D. B.; Raviraj, S.

    2016-06-01

    This paper presents the application of Taguchi approach to obtain optimal mix proportion for Self Compacting Concrete (SCC) containing spent foundry sand and M-sand. Spent foundry sand is used as a partial replacement for M-sand. The SCC mix has seven control factors namely, Coarse aggregate, M-sand with Spent Foundry sand, Cement, Fly ash, Water, Super plasticizer and Viscosity modifying agent. Modified Nan Su method is used to proportion the initial SCC mix. L18 (21×37) Orthogonal Arrays (OA) with the seven control factors having 3 levels is used in Taguchi approach which resulted in 18 SCC mix proportions. All mixtures are extensively tested both in fresh and hardened states to verify whether they meet the practical and technical requirements of SCC. The quality characteristics considering "Nominal the better" situation is applied to the test results to arrive at the optimal SCC mix proportion. Test results indicate that the optimal mix satisfies the requirements of fresh and hardened properties of SCC. The study reveals the feasibility of using spent foundry sand as a partial replacement of M-sand in SCC and also that Taguchi method is a reliable tool to arrive at optimal mix proportion of SCC.

  13. Retailer’s optimal ordering policies with cash discount and progressive payment scheme derived algebraically

    Directory of Open Access Journals (Sweden)

    Alok kumar

    2011-10-01

    Full Text Available This study presents optimal ordering policies for retailer when supplier offers cash discount and two progressive payment schemes for paying of purchasing cost. If the retailer pays the outstanding amount before or at first trade credit period M, the supplier provides r_1cash discount and does not charge any interest. If the retailer pays after M but before or at the second trade period N offered by the supplier, the supplier provides r_2 cash discount and charges interest on unpaid balance at the rate 〖Ic〗_1 . If retailer pays the balance after N, (N>M then the supplier does not provide any cash discount but charges interest on unpaid balance at the rate 〖Ic〗_2. The primary objective of this paper is to minimize the total cost of inventory system. This paper develops an algebraic approach to determine the optimal cycle time, optimal order quantity and optimal relevant cost. Numerical example are also presented to illustrate the result of propose model and solution procedure developed.

  14. An Optimization of (Q,r Inventory Policy Based on Health Care Apparel Products with Compound Poisson Demands

    Directory of Open Access Journals (Sweden)

    An Pan

    2014-01-01

    Full Text Available Addressing the problems of a health care center which produces tailor-made clothes for specific people, the paper proposes a single product continuous review model and establishes an optimal policy for the center based on (Q,r control policy to minimize expected average cost on an order cycle. A generic mathematical model to compute cost on real-time inventory level is developed to generate optimal order quantity under stochastic stock variation. The customer demands are described as compound Poisson process. Comparisons on cost between optimization method and experience-based decision on Q are made through numerical studies conducted for the inventory system of the center.

  15. Optimal pricing and inventory policies for non-instantaneous deteriorating items with permissible delay in payment: Fuzzy expected value model

    Directory of Open Access Journals (Sweden)

    Hardik N Soni

    2012-04-01

    Full Text Available This study investigates optimal pricing and inventory policies for non-instantaneous deteriorating items with permissible delay in payment. The demand rate is as known, continuous and differentiable function of price while holding cost rate, interest paid rate and interest earned rate are characterized as independent fuzzy variables rather than fuzzy numbers as in previous studies. Under these general assumptions, we first formulated a fuzzy expected value model (EVM and then some useful theoretical results have been derived to characterize the optimal solutions. An efficient algorithm is designed to determine the optimal pricing and inventory policy for the proposed model. The algorithmic procedure is demonstrated by means of numerical examples.

  16. Suboptimal and optimal order policies for fixed and varying replenishment interval with declining market

    Science.gov (United States)

    Yu, Jonas C. P.; Wee, H. M.; Yang, P. C.; Wu, Simon

    2016-06-01

    One of the supply chain risks for hi-tech products is the result of rapid technological innovation; it results in a significant decline in the selling price and demand after the initial launch period. Hi-tech products include computers and communication consumer's products. From a practical standpoint, a more realistic replenishment policy is needed to consider the impact of risks; especially when some portions of shortages are lost. In this paper, suboptimal and optimal order policies with partial backordering are developed for a buyer when the component cost, the selling price, and the demand rate decline at a continuous rate. Two mathematical models are derived and discussed: one model has the suboptimal solution with the fixed replenishment interval and a simpler computational process; the other one has the optimal solution with the varying replenishment interval and a more complicated computational process. The second model results in more profit. Numerical examples are provided to illustrate the two replenishment models. Sensitivity analysis is carried out to investigate the relationship between the parameters and the net profit.

  17. Modelling and optimization of proof testing policies for safety instrumented systems

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Echeverria, A.C. [Department of Automatic Control and System Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)], E-mail: a.torres@sheffield.ac.uk; Martorell, S. [Department of Chemical and Nuclear Engineering, Polytechnic University of Valencia, Cami de Vera sn, 4602, Valencia (Spain); Thompson, H.A. [Department of Automatic Control and System Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2009-04-15

    This paper introduces a new development for modelling the time-dependent probability of failure on demand of parallel architectures, and illustrates its application to multi-objective optimization of proof testing policies for safety instrumented systems. The model is based on the mean test cycle, which includes the different evaluation intervals that a module goes periodically through its time in service: test, repair and time between tests. The model is aimed at evaluating explicitly the effects of different test frequencies and strategies (i.e. simultaneous, sequential and staggered). It includes quantification of both detected and undetected failures, and puts special emphasis on the quantification of the contribution of the common cause failure to the system probability of failure on demand as an additional component. Subsequently, the paper presents the multi-objective optimization of proof testing policies with genetic algorithms, using this model for quantification of average probability of failure on demand as one of the objectives. The other two objectives are the system spurious trip rate and lifecycle cost. This permits balancing of the most important aspects of safety system implementation. The approach addresses the requirements of the standard IEC 61508. The overall methodology is illustrated through a practical application case of a protective system against high temperature and pressure of a chemical reactor.

  18. Optimal Control of the D-Policy M/G/1 Queueing System with Server Breakdowns

    Directory of Open Access Journals (Sweden)

    Kuo-Hsiung Wang

    2008-01-01

    Full Text Available This study deals with a single server in the D-policy M/G/1 queueing system in which the server is turned off at the end of each complete period and is activated again only when the cumulative completion times of the customers in the system exceeds a given level D. While the server is working, he is subject to breakdowns according to a Poisson process. When the server breaks down, he requires repair at a repair facility, where the repair time obeys a general distribution. We have demonstrated that the probability that the server is busy in the steady-state is equal to the traffic intensity. The total expected cost function per customer per unit time is constructed to determine the optimal operating D-policy at a minimum cost. We use the steady-state analytic results and apply an efficient Matlab computer program to calculate the optimal value of D. Based on three different service distributions: exponential, 3-stage Erlang and deterministic, we provide extensive numerical computation for illustration purpose. Sensitivity analysis is also investigated.

  19. Delay optimization for planar wireless sensor network with N-policy

    Institute of Scientific and Technical Information of China (English)

    陈志刚; 张德宇; 陈龙

    2014-01-01

    In N-policy, the nodes attempt to seize the channel when the number of packets in the buffer approaches N. The performance of N-policy on the energy efficiency is widely studied in the past years. And it is presented that there exists one optimal N to minimize the energy consumption. However, it is noticed that the delay raised by N-policy receives little attention. This work mathematically proves the delay to monotonically increase with increasing N in the collision-unfree channel. For planar network where the near-to-sink nodes burden heavier traffic than the external ones, the data stemming from the latter undergo longer delay. The various-N algorithm is proposed to address this phenomenon by decreasing the threshold N of outer nodes. Without the impacting on the network longevity, the maximum delay among the network has decreased 62.9% by the algorithm. Extensive simulations are given to verify the effectiveness and correctness of our analysis.

  20. INDEXABILITY AND OPTIMAL INDEX POLICIES FOR A CLASS OF REINITIALISING RESTLESS BANDITS

    Science.gov (United States)

    Villar, Sofía S.

    2016-01-01

    Motivated by a class of Partially Observable Markov Decision Processes with application in surveillance systems in which a set of imperfectly observed state processes is to be inferred from a subset of available observations through a Bayesian approach, we formulate and analyze a special family of multi-armed restless bandit problems. We consider the problem of finding an optimal policy for observing the processes that maximizes the total expected net rewards over an infinite time horizon subject to the resource availability. From the Lagrangian relaxation of the original problem, an index policy can be derived, as long as the existence of the Whittle index is ensured. We demonstrate that such a class of reinitializing bandits in which the projects’ state deteriorates while active and resets to its initial state when passive until its completion possesses the structural property of indexability and we further show how to compute the index in closed form. In general, the Whittle index rule for restless bandit problems does not achieve optimality. However, we show that the proposed Whittle index rule is optimal for the problem under study in the case of stochastically heterogenous arms under the expected total criterion, and it is further recovered by a simple tractable rule referred to as the 1-limited Round Robin rule. Moreover, we illustrate the significant suboptimality of other widely used heuristic: the Myopic index rule, by computing in closed form its suboptimality gap. We present numerical studies which illustrate for the more general instances the performance advantages of the Whittle index rule over other simple heuristics. PMID:27212781

  1. Impulse Control in Operations Research : Necessary Optimality Conditions, Sufficiency and Existence (replaced by CentER DP 2011-133)

    NARCIS (Netherlands)

    Chahim, M.; Hartl, R.F.; Kort, P.M.

    2011-01-01

    This paper considers a class of optimal control problems that allows jumps in the state variable. We present the necessary optimality conditions of the Impulse Control Maximum Principle based on the current value formulation. By reviewing the existing impulse control models in the literature, we poi

  2. Optimal harvesting policy of predator-prey model with free fishing and reserve zones

    Science.gov (United States)

    Toaha, Syamsuddin; Rustam

    2017-03-01

    The present paper deals with an optimal harvesting of predator-prey model in an ecosystem that consists of two zones, namely the free fishing and prohibited zones. The dynamics of prey population in the ecosystem can migrate from the free fishing to the prohibited zone and vice versa. The predator and prey populations in the free fishing zone are then harvested with constant efforts. The existence of the interior equilibrium point is analyzed and its stability is determined using Routh-Hurwitz stability test. The stable interior equilibrium point is then related to the problem of maximum profit and the problem of present value of net revenue. We follow the Pontryagin's maximal principle to get the optimal harvesting policy of the present value of the net revenue. From the analysis, we found a critical point of the efforts that makes maximum profit. There also exists certain conditions of the efforts that makes the present value of net revenue becomes maximal. In addition, the interior equilibrium point is locally asymptotically stable which means that the optimal harvesting is reached and the unharvested prey, harvested prey, and harvested predator populations remain sustainable. Numerical examples are given to verify the analytical results.

  3. Optimal Buyer’s Replenishment Policy in the Integrated Inventory Model for Imperfect Items

    Directory of Open Access Journals (Sweden)

    Lu Yueli

    2016-01-01

    Full Text Available In the classical economic order quantity (EOQ models, a common unrealistic assumption is that all the items received are of good quality. However, in realistic environment, a received shipment usually contains a fraction of imperfect quality items. These imperfect items may be scrapped, reworked at a cost, or salvaged at a discounted price. While the percentage of imperfect items is random, the optimal ordering cycle is rarely considered in current literatures. This paper revisits the model (Maddah and Jaber, 2008 and extends it by assuming that the ordering cycle is determined by the demand rate, delivery quantity per shipment, and the mathematical expectation of the defective rate. The possibility of stockout or residue in the end of a cycle will be considered, and the loss of stockout and the salvage of the residue are counted into the cost. Besides, we consider consolidating the shipments of imperfect items over multiple deliveries. Thus, an integrated vendor-buyer inventory model for imperfect quality items with equal-size shipment policy is established to derive the optimal ordering cycle, ordering quantity, and number of deliveries. The computational method of the optimal delivery quantity per shipment and number of deliveries is given through theoretical results. Finally, sensitivity of main parameters is analyzed through simulation experiments and shown by some figures.

  4. A sow replacement model using Bayesian updating in a three-level hierarchic Markov process. II. Optimization model

    DEFF Research Database (Denmark)

    Kristensen, Anders Ringgaard; Søllested, Thomas Algot

    2004-01-01

    herds. It is concluded that the Bayesian updating technique and the hierarchical structure decrease the size of the state space dramatically. Since parameter estimates vary considerably among herds it is concluded that decision support concerning sow replacement only makes sense with parameters...... estimated at herd level. It is argued that the multi-level formulation and the standard software comprise a flexible tool and a shortcut to working prototypes...

  5. Optimization of pricing and price policy of the enterprise in the conditions of financial and economic instability

    OpenAIRE

    Matsak, Alexander

    2015-01-01

    The subject of this Bachelors or of Art work is research of pricing and price policy of management company CJSC "Nash Standart" , which is included in group of companies Properties O1 enterprises, in the conditions of financial and economic instability. The purpose of work is search of ways of optimization of price policy in the market of commercial real estate. The management company CJSC "Nash Standart" is one of the leaders in the Moscow market in granting to clients professional services ...

  6. Optimization purchase price and the profit policy under vendor managed inventory

    Institute of Scientific and Technical Information of China (English)

    Guo Haifeng; Huang Xiaoyuan

    2005-01-01

    The optimization policy of the purchase price and the profit under vendor managed inventory(VMI) is studied.For a salable product, supply chain mode of VMI is established, which is based on deterministic demand, having initial stock and having stock-out cost. With the further analysis of the mode, VMI is found to increase profits of the buyer in the short-term motivation. But VMI will reduce profits of the supplier under the matching condition. And in the shortterm motivation, VMI will increase the purchase price to compensate the transfer cost of the supplier. As a result, the foundation of theory is provided to implement VMI in the supply chain, and have some definituded project significance.

  7. Optimal Ordering Policy of a Risk-Averse Retailer Subject to Inventory Inaccuracy

    Directory of Open Access Journals (Sweden)

    Lijing Zhu

    2013-01-01

    Full Text Available Inventory inaccuracy refers to the discrepancy between the actual inventory and the recorded inventory information. Inventory inaccuracy is prevalent in retail stores. It may result in a higher inventory level or poor customer service. Earlier studies of inventory inaccuracy have traditionally assumed risk-neutral retailers whose objective is to maximize expected profits. We investigate a risk-averse retailer within a newsvendor framework. The risk aversion attitude is measured by conditional-value-at-risk (CVaR. We consider inventory inaccuracy stemming both from permanent shrinkage and temporary shrinkage. Two scenarios of reducing inventory shrinkage are presented. In the first scenario, the retailer conducts physical inventory audits to identify the discrepancy. In the second scenario, the retailer deploys an automatic tracking technology, radiofrequency identification (RFID, to reduce inventory shrinkage. With the CVaR criterion, we propose optimal policies for the two scenarios. We show monotonicity between the retailer’s ordering policy and his risk aversion degree. A numerical analysis provides managerial insights for risk-averse retailers considering investing in RFID technology.

  8. Determining Inventory Replenishment Policy, Vehicle Type and Optimal Order Quantity in Critical Situation with Variable Lead Time

    Directory of Open Access Journals (Sweden)

    Mohammadali Pirayesh Neghab

    2014-01-01

    Full Text Available In Iran Khodro Khorasan, inventory replenishment policy of some items is based on certain simple model (Wilson model. Sometimes because of some reasons, goods reception may not be achieved at the planned time. This state is called as critical situation because the production line is on the eve of stop. The purpose of this paper is to present different inventory replenishment policies in critical situation. For each policy, the cost function that includes cost of line stop, ordering cost, holding cost and transportation cost has been modeled and through its minimization, vehicle type and optimal order quantity have been determined. This model has been used numerically for two items of Iran Khodro Khorasan. Findings show that applying the proposed policy leads to saved cost compared to the current policy of Iran Khodro Khorasan.

  9. On Optimality of Greedy Policy for a Class of Standard Reward Function of Restless Multi-armed Bandit Problem

    CERN Document Server

    Liu, Quan; Chen, Lin

    2011-01-01

    In this paper,we consider the restless bandit problem, which is one of the most well-studied generalizations of the celebrated stochastic multi-armed bandit problem in decision theory. However, it is known be PSPACE-Hard to approximate to any non-trivial factor. Thus the optimality is very difficult to obtain due to its high complexity. A natural method is to obtain the greedy policy considering its stability and simplicity. However, the greedy policy will result in the optimality loss for its intrinsic myopic behavior generally. In this paper, by analyzing one class of so-called standard reward function, we establish the closed-form condition about the discounted factor \\beta such that the optimality of the greedy policy is guaranteed under the discounted expected reward criterion, especially, the condition \\beta = 1 indicating the optimality of the greedy policy under the average accumulative reward criterion. Thus, the standard form of reward function can easily be used to judge the optimality of the greed...

  10. Linking energy policy, electricity generation and transmission using strong sustainability and co-optimization

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, Justin D.K.; Amaratunga, Gehan A.J. [University of Cambridge, Department of Engineering, 9 JJ Thomson Ave, Cambridge CB3 0FA (United Kingdom); Rodriguez, Cuauhtemoc [Cambridge Consultants (United Kingdom)

    2010-06-15

    The design of a sustainable electricity generation and transmission system is based on the established science of anthropogenic climate change and the realization that depending on imported fossil-fuels is becoming a measure of energy insecurity of supply. A model is proposed which integrates generation fuel mix composition, assignment of plants and optimized power flow, using Portugal as a case study. The result of this co-optimized approach is an overall set of generator types/fuels which increases the diversity of Portuguese electricity supply, lowers its dependency on imported fuels by 21.30% and moves the country towards meeting its regional and international obligations of 31% energy from renewables by 2020 and a 27% reduction in greenhouse gas emissions by 2012, respectively. The quantity and composition of power generation at each bus is specified, with particular focus on quantifying the amount of distributed generation. Based on other works, the resultant, overall distributed capacity penetration of 11.88% of total installed generation is expected to yield positive network benefits. Thus, the model demonstrates that national energy policy and technical deployment can be linked through sustainability and, moreover, that the respective goals may be mutually achieved via holistic, integrated design. (author)

  11. Bootstrapping and Conditional Simulation in Kriging : Better Confidence Intervals and Optimization (Replaced by CentER DP 2014-076)

    NARCIS (Netherlands)

    Mehdad, E.; Kleijnen, Jack P.C.

    2013-01-01

    Abstract: This paper investigates two related questions: (1) How to derive a confidence interval for the output of a combination of simulation inputs not yet simulated? (2) How to select the next combination to be simulated when searching for the optimal combination? To answer these questions, the

  12. Expected Improvement in Efficient Global Optimization Through Bootstrapped Kriging - Replaces CentER DP 2010-62

    NARCIS (Netherlands)

    Kleijnen, Jack P.C.; van Beers, W.C.M.; van Nieuwenhuyse, I.

    2011-01-01

    This article uses a sequentialized experimental design to select simulation input com- binations for global optimization, based on Kriging (also called Gaussian process or spatial correlation modeling); this Kriging is used to analyze the input/output data of the simulation model (computer code).

  13. Balancing Exploration, Uncertainty Representation and Computational Time in Many-Objective Reservoir Policy Optimization

    Science.gov (United States)

    Zatarain-Salazar, J.; Reed, P. M.; Quinn, J.; Giuliani, M.; Castelletti, A.

    2016-12-01

    As we confront the challenges of managing river basin systems with a large number of reservoirs and increasingly uncertain tradeoffs impacting their operations (due to, e.g. climate change, changing energy markets, population pressures, ecosystem services, etc.), evolutionary many-objective direct policy search (EMODPS) solution strategies will need to address the computational demands associated with simulating more uncertainties and therefore optimizing over increasingly noisy objective evaluations. Diagnostic assessments of state-of-the-art many-objective evolutionary algorithms (MOEAs) to support EMODPS have highlighted that search time (or number of function evaluations) and auto-adaptive search are key features for successful optimization. Furthermore, auto-adaptive MOEA search operators are themselves sensitive to having a sufficient number of function evaluations to learn successful strategies for exploring complex spaces and for escaping from local optima when stagnation is detected. Fortunately, recent parallel developments allow coordinated runs that enhance auto-adaptive algorithmic learning and can handle scalable and reliable search with limited wall-clock time, but at the expense of the total number of function evaluations. In this study, we analyze this tradeoff between parallel coordination and depth of search using different parallelization schemes of the Multi-Master Borg on a many-objective stochastic control problem. We also consider the tradeoff between better representing uncertainty in the stochastic optimization, and simplifying this representation to shorten the function evaluation time and allow for greater search. Our analysis focuses on the Lower Susquehanna River Basin (LSRB) system where multiple competing objectives for hydropower production, urban water supply, recreation and environmental flows need to be balanced. Our results provide guidance for balancing exploration, uncertainty, and computational demands when using the EMODPS

  14. Optimizing two-dimensional renewable warranty policies for sensor embedded remanufactured products

    Directory of Open Access Journals (Sweden)

    Ammar Alqahtani

    2017-05-01

    Full Text Available Purpose: Remanufactured products, in addition to being environment friendly, are popular with consumers because they can offer the latest technology with lower prices in comparison to brand new products. However, some consumers are hesitant to buy remanufactured products because they are skeptical about the quality of the remanufactured product and thus are unsure of the extent to which the product will render services when compared to a new product. A strategy that remanufacturers may employ to entice customers is to offer warranties on remanufactured products. To that end, this paper studies and scrutinizes the impact of offering renewing warranties on remanufactured products. Specifically, the paper suggests a methodology which simultaneously minimizes the cost incurred by the remanufacturers and maximizes the confidence of the consumers towards buying remanufacturing products. Design/methodology/approach: This study uses discrete-event simulation to optimize the implementation of a two-dimensional renewing warranty policy for remanufactured products. The implementation is illustrated using a specific product recovery system called the Advanced Remanufacturing-To-Order (ARTO system. The experiments used in the study were designed using Taguchi’s Orthogonal Arrays to represent the entire domain of the recovery system so as to observe the system behavior under various experimental conditions. In order to determine the optimum strategy offered by the remanufacturer, various warranty and preventive maintenance scenarios were analyzed using pairwise t-tests along with one-way analysis of variance (ANOVA and Tukey pairwise comparisons tests for every scenario. Findings: The proposed methodology is able to simultaneously minimize the cost incurred by the remanufacturer, optimize the warranty price and period, and optimize the preventive maintenance strategy resulting in increased consumer confidence. Originality/value: This is the first study that

  15. Optimal harvesting policy of a stochastic two-species competitive model with Lévy noise in a polluted environment

    Science.gov (United States)

    Zhao, Yu; Yuan, Sanling

    2017-07-01

    As well known that the sudden environmental shocks and toxicant can affect the population dynamics of fish species, a mechanistic understanding of how sudden environmental change and toxicant influence the optimal harvesting policy requires development. This paper presents the optimal harvesting of a stochastic two-species competitive model with Lévy noise in a polluted environment, where the Lévy noise is used to describe the sudden climate change. Due to the discontinuity of the Lévy noise, the classical optimal harvesting methods based on the explicit solution of the corresponding Fokker-Planck equation are invalid. The object of this paper is to fill up this gap and establish the optimal harvesting policy. By using of aggregation and ergodic methods, the approximation of the optimal harvesting effort and maximum expectation of sustainable yields are obtained. Numerical simulations are carried out to support these theoretical results. Our analysis shows that the Lévy noise and the mean stress measure of toxicant in organism may affect the optimal harvesting policy significantly.

  16. A note on optimal (s,S) and (R,nQ) policies under a stuttering Poisson demand process

    DEFF Research Database (Denmark)

    Larsen, Christian

    2015-01-01

    In this note, a new efficient algorithm is proposed to find an optimal (s, S) replenishment policy for inventory systems with continuous reviews and where the demand follows a stuttering Poisson process (the compound element is geometrically distributed). We also derive three upper bounds...

  17. Assessing the Optimal Length of Parental Leave for Child and Parental Well-Being: How Can Research Inform Policy?

    Science.gov (United States)

    Galtry, Judith; Callister, Paul

    2005-01-01

    Parental leave is a complex area of public policy. Concerns include health protection for working mothers, equal employment opportunities for women, access to adequate antenatal and birthing care, maternal recovery, optimal nutrition for infants, and gender equality within families. Given this complexity, the design of parental leave schemes,…

  18. A note on optimal (s,S) and (R,nQ) policies under a stuttering Poisson demand process

    DEFF Research Database (Denmark)

    Larsen, Christian

    2015-01-01

    In this note, a new efficient algorithm is proposed to find an optimal (s, S) replenishment policy for inventory systems with continuous reviews and where the demand follows a stuttering Poisson process (the compound element is geometrically distributed). We also derive three upper bounds for the...

  19. Optimal management for infinite capacity N-policy M/G/1 queue with a removable service station

    Science.gov (United States)

    Chang, Y. C.; Pearn, W. L.

    2011-07-01

    In this article, we consider an infinite capacity N-policy M/G/1 queueing system with a single removable server. Poisson arrivals and general distribution service times are assumed. The server is controllable that may be turned on at arrival epochs or off at service completion epochs. We apply a differential technique to study system sensitivity, which examines the effect of different system input parameters on the system. A cost model for infinite capacity queueing system under steady-state condition is developed, to determine the optimal management policy at minimum cost. Analytical results for sensitivity analysis are derived. We also provide extensive numerical computations to illustrate the analytical sensitivity properties obtained. Finally, an application example is presented to demonstrate how the model could be used in real applications to obtain the optimal management policy.

  20. Ankle replacement

    Science.gov (United States)

    Ankle arthroplasty - total; Total ankle arthroplasty; Endoprosthetic ankle replacement; Ankle surgery ... You may not be able to have a total ankle replacement if you have had ankle joint infections in ...

  1. Knee Replacement

    Science.gov (United States)

    Knee replacement is surgery for people with severe knee damage. Knee replacement can relieve pain and allow you to ... Your doctor may recommend it if you have knee pain and medicine and other treatments are not ...

  2. Optimal Pricing and Ordering Policy for Two Echelon Varying Production Inventory System

    Directory of Open Access Journals (Sweden)

    Brojeswar Pal

    2014-01-01

    Full Text Available The paper proposes a two-stage supply chain model for price sensitive demand in imperfect production system while manufacturer and supplier are the members of the chain. The supplier screens the raw materials first and supplies good materials to the manufacturer at a constant rate. The production rate varies randomly within a finite interval. The inventory cycle of the manufacturer starts with shortages and production and it finishes with shortages again, in which shortages are partially backlogged. We consider a mixture of LIFO (last in, first out and FIFO (first in, first out dispatching policies to fill the backlogged demand. Thus, the objective of the proposed paper is to determine the optimal ordering lot-size and selling price of the manufacturer such that the per unit average integrated expected profit of the supply chain model is maximized. A numerical example is provided to analyze and illustrate the behavior and application of the model. Finally, sensitivity analysis of the key parameters are presented to test feasibility of the model.

  3. Optimal demand reponse to water pricing policies under limited water supply in irrigation: a case study

    Science.gov (United States)

    Grießbach, Ulkrike; Stange, Peter; Schuetze, Niels

    2015-04-01

    Due to climate change, extreme weather conditions such as droughts may have an increasing impact on irrigated agriculture. To cope with the higher demand of water, a new decision support framework is developed which focuses on an integrated management of both irrigation water supply and demand. For modeling the regional water demand, local stochastic water demand functions are used which are derived from optimized agronomic response on farms scale. These functions take into account different soil types, crops, stochastically generated climate scenarios considering different economic conditions, e.g., variable and fixed costs. This generic approach enables the consideration of both multiple crops at farm scale as well as of the aggregated response to water pricing at a regional scale for full and deficit irrigation systems. Within the SAPHIR (SAxonian Platform for High Performance IRrigation) project a prototype of a decision support system is developed and applied for a case study in Saxony which helps to evaluate combined water supply and demand management policies on a regional level.

  4. A Jackson network model and threshold policy for joint optimization of energy and delay in multi-hop wireless networks

    KAUST Repository

    Xia, Li

    2014-11-20

    This paper studies the joint optimization problem of energy and delay in a multi-hop wireless network. The optimization variables are the transmission rates, which are adjustable according to the packet queueing length in the buffer. The optimization goal is to minimize the energy consumption of energy-critical nodes and the packet transmission delay throughout the network. In this paper, we aim at understanding the well-known decentralized algorithms which are threshold based from a different research angle. By using a simplified network model, we show that we can adopt the semi-open Jackson network model and study this optimization problem in closed form. This simplified network model further allows us to establish some significant optimality properties. We prove that the system performance is monotonic with respect to (w.r.t.) the transmission rate. We also prove that the threshold-type policy is optimal, i.e., when the number of packets in the buffer is larger than a threshold, transmit with the maximal rate (power); otherwise, no transmission. With these optimality properties, we develop a heuristic algorithm to iteratively find the optimal threshold. Finally, we conduct some simulation experiments to demonstrate the main idea of this paper.

  5. An Optimization Model for Expired Drug Recycling Logistics Networks and Government Subsidy Policy Design Based on Tri-level Programming

    Directory of Open Access Journals (Sweden)

    Hui Huang

    2015-07-01

    Full Text Available In order to recycle and dispose of all people’s expired drugs, the government should design a subsidy policy to stimulate users to return their expired drugs, and drug-stores should take the responsibility of recycling expired drugs, in other words, to be recycling stations. For this purpose it is necessary for the government to select the right recycling stations and treatment stations to optimize the expired drug recycling logistics network and minimize the total costs of recycling and disposal. This paper establishes a tri-level programming model to study how the government can optimize an expired drug recycling logistics network and the appropriate subsidy policies. Furthermore, a Hybrid Genetic Simulated Annealing Algorithm (HGSAA is proposed to search for the optimal solution of the model. An experiment is discussed to illustrate the good quality of the recycling logistics network and government subsides obtained by the HGSAA. The HGSAA is proven to have the ability to converge on the global optimal solution, and to act as an effective algorithm for solving the optimization problem of expired drug recycling logistics network and government subsidies.

  6. An Optimization Model for Expired Drug Recycling Logistics Networks and Government Subsidy Policy Design Based on Tri-level Programming.

    Science.gov (United States)

    Huang, Hui; Li, Yuyu; Huang, Bo; Pi, Xing

    2015-07-01

    In order to recycle and dispose of all people's expired drugs, the government should design a subsidy policy to stimulate users to return their expired drugs, and drug-stores should take the responsibility of recycling expired drugs, in other words, to be recycling stations. For this purpose it is necessary for the government to select the right recycling stations and treatment stations to optimize the expired drug recycling logistics network and minimize the total costs of recycling and disposal. This paper establishes a tri-level programming model to study how the government can optimize an expired drug recycling logistics network and the appropriate subsidy policies. Furthermore, a Hybrid Genetic Simulated Annealing Algorithm (HGSAA) is proposed to search for the optimal solution of the model. An experiment is discussed to illustrate the good quality of the recycling logistics network and government subsides obtained by the HGSAA. The HGSAA is proven to have the ability to converge on the global optimal solution, and to act as an effective algorithm for solving the optimization problem of expired drug recycling logistics network and government subsidies.

  7. Optimal Sensing and Actuation Policies for Networked Mobile Agents in a Class of Cyber-Physical Systems

    OpenAIRE

    Tricaud, Christophe

    2010-01-01

    The main purpose of this dissertation is to define and solve problems on optimal sensing and actuating policies in Cyber-Physical Systems (CPSs). Cyber-physical system is a term that was introduced recently to define the increasing complexity of the interactions between computational hardwares and their physical environments. The problem of designing the ``cyber'' part may not be trivial but can be solved from scratch. However, the ``physical'' part, usually a natural physical process, is inh...

  8. Using Complete Squares Method to Optimize Replenishment Policies in a Four-Stage Supply Chain with Planned Backorders

    OpenAIRE

    M. E. Seliaman

    2011-01-01

    We develop a four-stage, serial supply chain inventory model with planned backorders. This supply chain model is formulated for the integer multipliers coordination mechanism, where firms at the same stage of the supply chain use the same cycle time and the cycle time at each stage is an integer multiplier of the cycle time used at the adjacent downstream stage. We develop an optimal replenishment policy using a simple algebraic method to solve the problem without the use of differential calc...

  9. Optimization of the Import Policy as a Factor of Foreign Trade Safety

    Directory of Open Access Journals (Sweden)

    Vlasiuk Taras O.

    2015-03-01

    Full Text Available The article considers the issues of ensuring the state foreign trade safety by using the tools of import policy. The analysis of the current condition of Ukraine import and import policy was carried out, the individual tools of the import policy were analyzed, a list of problems with the import that threaten separate industries of Ukraine was given, the measures, which implementation will positively affect the level of foreign trade safety of the state, were proposed.

  10. Optimal Policy of Cross-Layer Design for Channel Access and Transmission Rate Adaptation in Cognitive Radio Networks

    Science.gov (United States)

    He, Hao; Wang, Jun; Zhu, Jiang; Li, Shaoqian

    2010-12-01

    In this paper, we investigate the cross-layer design of joint channel access and transmission rate adaptation in CR networks with multiple channels for both centralized and decentralized cases. Our target is to maximize the throughput of CR network under transmission power constraint by taking spectrum sensing errors into account. In centralized case, this problem is formulated as a special constrained Markov decision process (CMDP), which can be solved by standard linear programming (LP) method. As the complexity of finding the optimal policy by LP increases exponentially with the size of action space and state space, we further apply action set reduction and state aggregation to reduce the complexity without loss of optimality. Meanwhile, for the convenience of implementation, we also consider the pure policy design and analyze the corresponding characteristics. In decentralized case, where only local information is available and there is no coordination among the CR users, we prove the existence of the constrained Nash equilibrium and obtain the optimal decentralized policy. Finally, in the case that the traffic load parameters of the licensed users are unknown for the CR users, we propose two methods to estimate the parameters for two different cases. Numerical results validate the theoretic analysis.

  11. Optimal Policy of Cross-Layer Design for Channel Access and Transmission Rate Adaptation in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Jiang Zhu

    2010-01-01

    Full Text Available In this paper, we investigate the cross-layer design of joint channel access and transmission rate adaptation in CR networks with multiple channels for both centralized and decentralized cases. Our target is to maximize the throughput of CR network under transmission power constraint by taking spectrum sensing errors into account. In centralized case, this problem is formulated as a special constrained Markov decision process (CMDP, which can be solved by standard linear programming (LP method. As the complexity of finding the optimal policy by LP increases exponentially with the size of action space and state space, we further apply action set reduction and state aggregation to reduce the complexity without loss of optimality. Meanwhile, for the convenience of implementation, we also consider the pure policy design and analyze the corresponding characteristics. In decentralized case, where only local information is available and there is no coordination among the CR users, we prove the existence of the constrained Nash equilibrium and obtain the optimal decentralized policy. Finally, in the case that the traffic load parameters of the licensed users are unknown for the CR users, we propose two methods to estimate the parameters for two different cases. Numerical results validate the theoretic analysis.

  12. Optimal Ordering and Pricing Policies for Seasonal Products: Impacts of Demand Uncertainty and Capital Constraint

    National Research Council Canada - National Science Library

    Jinzhao Shi; Richard Y. K. Fung; Ju'e Guo

    2016-01-01

      With a stochastic price-dependent market demand, this paper investigates how demand uncertainty and capital constraint affect retailer's integrated ordering and pricing policies towards seasonal products...

  13. Directed Replacement

    CERN Document Server

    Karttunen, L

    1996-01-01

    This paper introduces to the finite-state calculus a family of directed replace operators. In contrast to the simple replace expression, UPPER -> LOWER, defined in Karttunen (ACL-95), the new directed version, UPPER @-> LOWER, yields an unambiguous transducer if the lower language consists of a single string. It transduces the input string from left to right, making only the longest possible replacement at each point. A new type of replacement expression, UPPER @-> PREFIX ... SUFFIX, yields a transducer that inserts text around strings that are instances of UPPER. The symbol ... denotes the matching part of the input which itself remains unchanged. PREFIX and SUFFIX are regular expressions describing the insertions. Expressions of the type UPPER @-> PREFIX ... SUFFIX may be used to compose a deterministic parser for a ``local grammar'' in the sense of Gross (1989). Other useful applications of directed replacement include tokenization and filtering of text streams.

  14. Multi-policy improvement in stochastic optimization with forward recursive function criteria

    Science.gov (United States)

    Chang, Hyeong Soo

    2005-05-01

    Iwamoto recently established a formal transformation via an invariant imbedding to construct a controlled Markov chain that can be solved in a backward manner, as in backward induction for finite-horizon Markov decision processes (MDPs), for a given controlled Markov chain with non-additive forward recursive objective function criterion. Chang et al. presented formal methods, called "parallel rollout" and "policy switching," of combining given multiple policies in MDPs and showed that the policies generated by both methods improve all of the policies that the methods combine. This brief paper extends the methods of parallel rollout and policy switching for forward recursive objective function criteria and shows that the similar property holds as in MDPs. We further discuss how to implement these methods via simulation.

  15. The Optimal Replenishment Policy under Trade Credit Financing with Ramp Type Demand and Demand Dependent Production Rate

    Directory of Open Access Journals (Sweden)

    Juanjuan Qin

    2014-01-01

    Full Text Available This paper investigates the optimal replenishment policy for the retailer with the ramp type demand and demand dependent production rate involving the trade credit financing, which is not reported in the literatures. First, the two inventory models are developed under the above situation. Second, the algorithms are given to optimize the replenishment cycle time and the order quantity for the retailer. Finally, the numerical examples are carried out to illustrate the optimal solutions and the sensitivity analysis is performed. The results show that if the value of production rate is small, the retailer will lower the frequency of putting the orders to cut down the order cost; if the production rate is high, the demand dependent production rate has no effect on the optimal decisions. When the trade credit is less than the growth stage time, the retailer will shorten the replenishment cycle; when it is larger than the breakpoint of the demand, within the maturity stage of the products, the trade credit has no effect on the optimal order cycle and the optimal order quantity.

  16. Optimal C-arm angulation during transcatheter aortic valve replacement: Accuracy of a rotational C-arm computed tomography based three dimensional heart model.

    Science.gov (United States)

    Veulemans, Verena; Mollus, Sabine; Saalbach, Axel; Pietsch, Max; Hellhammer, Katharina; Zeus, Tobias; Westenfeld, Ralf; Weese, Jürgen; Kelm, Malte; Balzer, Jan

    2016-10-26

    To investigate the accuracy of a rotational C-arm CT-based 3D heart model to predict an optimal C-arm configuration during transcatheter aortic valve replacement (TAVR). Rotational C-arm CT (RCT) under rapid ventricular pacing was performed in 57 consecutive patients with severe aortic stenosis as part of the pre-procedural cardiac catheterization. With prototype software each RCT data set was segmented using a 3D heart model. From that the line of perpendicularity curve was obtained that generates a perpendicular view of the aortic annulus according to the right-cusp rule. To evaluate the accuracy of a model-based overlay we compared model- and expert-derived aortic root diameters. For all 57 patients in the RCT cohort diameter measurements were obtained from two independent operators and were compared to the model-based measurements. The inter-observer variability was measured to be in the range of 0°-12.96° of angular C-arm displacement for two independent operators. The model-to-operator agreement was 0°-13.82°. The model-based and expert measurements of aortic root diameters evaluated at the aortic annulus (r = 0.79, P r = 0.93, P r = 0.92, P < 0.01) correlated on a high level and the Bland-Altman analysis showed good agreement. The interobserver measurements did not show a significant bias. Automatic segmentation of the aortic root using an anatomical model can accurately predict an optimal C-arm configuration, potentially simplifying current clinical workflows before and during TAVR.

  17. Optimal Monetary Policy with Durable Consumption Goods and Factor Demand Linkages

    DEFF Research Database (Denmark)

    Petrella, Ivan; Santoro, Emiliano

    This paper deals with the implications of factor demand linkages for monetary policy design. We develop a dynamic general equilibrium model with two sectors that produce durable and non-durable goods, respectively. Part of the output produced in each sector is used as an intermediate input......-durable spending in response to a monetary policy shock. A main result of our monetary policy analysis is that strategic complementarities generated by factor demand linkages amplify social welfare loss. As the degree of interconnection between sectors increases, the cost of misperceiving the correct production...

  18. Knee Replacement

    Science.gov (United States)

    ... need knee replacement surgery usually have problems walking, climbing stairs, and getting in and out of chairs. Some ... a total living space on one floor since climbing stairs can be difficult. Install safety bars or a ...

  19. The Level Of Corporate Dividend Payout To Stockholders: Does Optimal Dividend Policy Exist For Firms Quoted At The Nairobi Stock Exchange?

    National Research Council Canada - National Science Library

    Bitok Kibet; Tenai Joel; Cheruiyot Thomas; Maru Loice; Kipsat Mary

    2010-01-01

    The objective of this study was to determine the level of corporate dividend payout to stockholders and establish if the optimal dividend policy exists for the firms quoted at the Nairobi Stock Exchange (NSE...

  20. Optimal climate change: economics and climate science policy histories (from heuristic to normative).

    Science.gov (United States)

    Randalls, Samuel

    2011-01-01

    Historical accounts of climate change science and policy have reflected rather infrequently upon the debates, discussions, and policy advice proffered by economists in the 1980s. While there are many forms of economic analysis, this article focuses upon cost-benefit analysis, especially as adopted in the work of William Nordhaus. The article addresses the way in which climate change economics subtly altered debates about climate policy from the late 1970s through the 1990s. These debates are often technical and complex, but the argument in this article is that the development of a philosophy of climate change as an issue for cost-benefit analysis has had consequences for how climate policy is made today.

  1. Reinforcement learning based sensing policy optimization for energy efficient cognitive radio networks

    CERN Document Server

    Oksanen, Jan; Koivunen, Visa

    2011-01-01

    This paper introduces a machine learning based collaborative multi band spectrum sensing policy for cognitive radios. The proposed sensing policy guides secondary users to focus the search of unused radio spectrum to those frequencies that persistently provide them high data rate. The proposed policy is based on machine learning, which makes it adaptive with the temporally and spatially varying radio spectrum. Furthermore, there is no need for dynamic modeling of the primary activity since it is implicitly learned over time. Energy efficiency is achieved by minimizing the number of assigned sensors per each subband under a constraint on miss detection probability. It is important to control the missed detections because they cause collisions with primary transmissions and lead to retransmissions at both the primary and secondary user. The minimization of the number of active sensors is formulated as a binary integer programming problem. Simulations show that the proposed machine learning based sensing policy ...

  2. A linear programming model to optimize diets in environmental policy scenarios.

    Science.gov (United States)

    Moraes, L E; Wilen, J E; Robinson, P H; Fadel, J G

    2012-03-01

    The objective was to develop a linear programming model to formulate diets for dairy cattle when environmental policies are present and to examine effects of these policies on diet formulation and dairy cattle nitrogen and mineral excretions as well as methane emissions. The model was developed as a minimum cost diet model. Two types of environmental policies were examined: a tax and a constraint on methane emissions. A tax was incorporated to simulate a greenhouse gas emissions tax policy, and prices of carbon credits in the current carbon markets were attributed to the methane production variable. Three independent runs were made, using carbon dioxide equivalent prices of $5, $17, and $250/t. A constraint was incorporated into the model to simulate the second type of environmental policy, reducing methane emissions by predetermined amounts. The linear programming formulation of this second alternative enabled the calculation of marginal costs of reducing methane emissions. Methane emission and manure production by dairy cows were calculated according to published equations, and nitrogen and mineral excretions were calculated by mass conservation laws. Results were compared with respect to the values generated by a base least-cost model. Current prices of the carbon credit market did not appear onerous enough to have a substantive incentive effect in reducing methane emissions and altering diet costs of our hypothetical dairy herd. However, when emissions of methane were assumed to be reduced by 5, 10, and 13.5% from the base model, total diet costs increased by 5, 19.1, and 48.5%, respectively. Either these increased costs would be passed onto the consumer or dairy producers would go out of business. Nitrogen and potassium excretions were increased by 16.5 and 16.7% with a 13.5% reduction in methane emissions from the base model. Imposing methane restrictions would further increase the demand for grains and other human-edible crops, which is not a progressive

  3. An Analysis of Policy Optimization concerning Sustainable Agricultural Development in China Based on 2014 US Farm Bill

    Institute of Scientific and Technical Information of China (English)

    Zhongxing LI; Joseph J.Molnar; Shunqiang SUN

    2016-01-01

    On the basis of ensuring farmers’ income,the US 2014 Farm Bill emphasizes resources and environmental protection,and some policies and measures to promote rural development,sustainable agricultural development and agricultural science and technology,which provides a good lesson for China’s agricultural policy on how to ensure sustainable agricultural development. Finally,we set forth the following recommendations: speeding up the establishment of a legal system of modern agriculture; optimizing agricultural safety net and strengthening agricultural risk management and control; establishing agricultural science and technology extension system and adjusting agricultural planting structure; establishing farmers’ associations,nurturing new farmers and protecting the legitimate rights and interests of farmers; increasing environmental remediation investment and efforts.

  4. Using Complete Squares Method to Optimize Replenishment Policies in a Four-Stage Supply Chain with Planned Backorders

    Directory of Open Access Journals (Sweden)

    M. E. Seliaman

    2011-01-01

    Full Text Available We develop a four-stage, serial supply chain inventory model with planned backorders. This supply chain model is formulated for the integer multipliers coordination mechanism, where firms at the same stage of the supply chain use the same cycle time and the cycle time at each stage is an integer multiplier of the cycle time used at the adjacent downstream stage. We develop an optimal replenishment policy using a simple algebraic method to solve the problem without the use of differential calculus.

  5. OPTIMAL ORDERING POLICY FOR THE TIME DEPENDENT DETERIORATION WITH ASSOCIATED SALVAGE VALUE WHEN DELAY IN PAYMENTS IS PERMISSIBLE

    Directory of Open Access Journals (Sweden)

    Nita H. Shah *, Poonam Pandey*

    2008-09-01

    Full Text Available In this research article, an attempt is made to develop mathematical model when units in inventory are subject to deterioration with time, and the supplier offers his retailer the credit period to settle the account of the procurement units. The salvage value is associated to the deterioration units. The objective is to minimize the retailer’s total inventory cost. An algorithm is proposed to find optimal ordering policy. A numerical example is given to study the effect of allowable credit period and deterioration on decision variable and the total cost of the retailer.

  6. Optimal Inventory Policy Involving Ordering Cost Reduction, Back-Order Discounts, and Variable Lead Time Demand by Minimax Criterion

    Directory of Open Access Journals (Sweden)

    Jong-Wuu Wu

    2009-01-01

    Full Text Available This paper allows the backorder rate as a control variable to widen applications of a continuous review inventory model. Moreover, we also consider the backorder rate that is proposed by combining Ouyang and Chuang (2001 (or Lee (2005 with Pan and Hsiao (2001 to present a new form. Thus, the backorder rate is dependent on the amount of shortages and backorder price discounts. Besides, we also treat the ordering cost as a decision variable. Hence, we develop an algorithmic procedure to find the optimal inventory policy by minimax criterion. Finally, a numerical example is also given to illustrate the results.

  7. Patient dumping, outlier payments, and optimal healthcare payment policy under asymmetric information.

    Science.gov (United States)

    Takahara, Tsuyoshi

    2016-12-01

    We analyze a rationale for official authorization of patient dumping in the prospective payment policy framework. We show that when the insurer designs the healthcare payment policy to let hospitals dump high-cost patients, there is a trade-off between the disutility of dumped patients (changes in hospitals' rent extraction due to low-severity patients) and the shift in the level of cost reduction efforts for high-severity patients. We also clarify the welfare-improving conditions by allowing hospitals to dump high-severity patients. Finally, we show that if the efficiency of the cost reduction efforts varies extensively and the healthcare payment cost is substantial, or if there are many private hospitals, the patient dumping policy can improve social welfare in a wider environment.

  8. Esophageal replacement.

    Science.gov (United States)

    Kunisaki, Shaun M; Coran, Arnold G

    2017-04-01

    This article focuses on esophageal replacement as a surgical option for pediatric patients with end-stage esophageal disease. While it is obvious that the patient׳s own esophagus is the best esophagus, persisting with attempts to retain a native esophagus with no function and at all costs are futile and usually detrimental to the overall well-being of the child. In such cases, the esophagus should be abandoned, and the appropriate esophageal replacement is chosen for definitive reconstruction. We review the various types of conduits used for esophageal replacement and discuss the unique advantages and disadvantages that are relevant for clinical decision-making. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Value of a noise-optimized virtual monoenergetic reconstruction technique in dual-energy CT for planning of transcatheter aortic valve replacement

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Simon S.; Albrecht, Moritz H.; Wichmann, Julian L.; Huesers, Kristina; Scholtz, Jan-Erik; Booz, Christian; Bodelle, Boris; Bauer, Ralf W.; Metzger, Sarah C.; Vogl, Thomas J.; Lehnert, Thomas [University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany)

    2017-02-15

    To evaluate objective and subjective image quality of a noise-optimized virtual monoenergetic imaging (VMI+) reconstruction technique in dual-energy computed tomography (DECT) angiography prior to transcatheter aortic valve replacement (TAVR). Datasets of 47 patients (35 men; 64.1 ± 10.9 years) who underwent DECT angiography of heart and vascular access prior to TAVR were reconstructed with standard linear blending (F{sub 0}.5), VMI+, and traditional monoenergetic (VMI) algorithms in 10-keV intervals from 40-100 keV. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of 564 arterial segments were evaluated. Subjective analysis was rated by three blinded observers using a Likert scale. Mean SNR and CNR were highest in 40 keV VMI+ series (SNR, 27.8 ± 13.0; CNR, 26.3 ± 12.7), significantly (all p < 0.001) superior to all VMI series, which showed highest values at 70 keV (SNR, 18.5 ± 7.6; CNR, 16.0 ± 7.4), as well as linearly-blended F{sub 0}.5 series (SNR, 16.8 ± 7.3; CNR, 13.6 ± 6.9). Highest subjective image quality scores were observed for 40, 50, and 60 keV VMI+ reconstructions (all p > 0.05), significantly superior to all VMI and standard linearly-blended images (all p < 0.01). Low-keV VMI+ reconstructions significantly increase CNR and SNR compared to VMI and standard linear-blending image reconstruction and improve subjective image quality in preprocedural DECT angiography in the context of TAVR planning. (orig.)

  10. Noncoplanar Beam Angle Class Solutions to Replace Time-Consuming Patient-Specific Beam Angle Optimization in Robotic Prostate Stereotactic Body Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, Linda, E-mail: l.rossi@erasmusmc.nl; Breedveld, Sebastiaan; Aluwini, Shafak; Heijmen, Ben

    2015-07-15

    Purpose: To investigate development of a recipe for the creation of a beam angle class solution (CS) for noncoplanar prostate stereotactic body radiation therapy to replace time-consuming individualized beam angle selection (iBAS) without significant loss in plan quality, using the in-house “Erasmus-iCycle” optimizer for fully automated beam profile optimization and iBAS. Methods and Materials: For 30 patients, Erasmus-iCycle was first used to generate 15-, 20-, and 25-beam iBAS plans for a CyberKnife equipped with a multileaf collimator. With these plans, 6 recipes for creation of beam angle CSs were investigated. Plans of 10 patients were used to create CSs based on the recipes, and the other 20 to independently test them. For these tests, Erasmus-iCycle was also used to generate intensity modulated radiation therapy plans for the fixed CS beam setups. Results: Of the tested recipes for CS creation, only 1 resulted in 15-, 20-, and 25-beam noncoplanar CSs without plan deterioration compared with iBAS. For the patient group, mean differences in rectum D{sub 1cc}, V{sub 60GyEq}, V{sub 40GyEq}, and D{sub mean} between 25-beam CS plans and 25-beam plans generated with iBAS were 0.2 ± 0.4 Gy, 0.1% ± 0.2%, 0.2% ± 0.3%, and 0.1 ± 0.2 Gy, respectively. Differences between 15- and 20-beam CS and iBAS plans were also negligible. Plan quality for CS plans relative to iBAS plans was also preserved when narrower planning target volume margins were arranged and when planning target volume dose inhomogeneity was decreased. Using a CS instead of iBAS reduced the computation time by a factor of 14 to 25, mainly depending on beam number, without loss in plan quality. Conclusions: A recipe for creation of robust beam angle CSs for robotic prostate stereotactic body radiation therapy has been developed. Compared with iBAS, computation times decreased by a factor 14 to 25. The use of a CS may avoid long planning times without losses in plan quality.

  11. Optimal Replenishment Policy for Weibull-Distributed Deteriorating Items with Trapezoidal Demand Rate and Partial Backlogging

    Directory of Open Access Journals (Sweden)

    Lianxia Zhao

    2016-01-01

    Full Text Available An inventory model for Weibull-distributed deteriorating items is considered so as to minimize the total cost per unit time in this paper. The model starts with shortage, allowed partial backlogging, and trapezoidal demand rate. By analyzing the model, an efficient solution procedure is proposed to determine the optimal replenishment and the optimal order quantity and the average total costs are also obtained. Finally, numerical examples are provided to illustrate the theoretical results and a sensitivity analysis of the major parameters with respect to the stability of optimal solution is also carried out.

  12. Unravelling the concept of consumer preference: implications for health policy and optimal planning in primary care.

    Science.gov (United States)

    Foster, Michele M; Earl, Peter E; Haines, Terry P; Mitchell, Geoffrey K

    2010-10-01

    Accounting for consumer preference in health policy and delivery system design makes good economic sense since this is linked to outcomes, quality of care and cost control. Probability trade-off methods are commonly used in policy evaluation, marketing and economics. Increasingly applied to health matters, the trade-off preference model has indicated that consumers of health care discriminate between different attributes of care. However, the complexities of the health decision-making environment raise questions about the inherent assumptions concerning choice and decision-making behavior which frame this view of consumer preference. In this article, we use the example of primary care in Australia as a vehicle to examine the concept of 'consumer preference' from different perspectives within economics and discuss the significance of how we model preferences for health policy makers. In doing so, we question whether mainstream thinking, namely that consumers are capable of deliberating between rival strategies and are willing to make trade-offs, is a reliable way of thinking about preferences given the complexities of the health decision-making environment. Alternative perspectives on preference can assist health policy makers and health providers by generating more precise information about the important attributes of care that are likely to enhance consumer engagement and optimise acceptability of health care.

  13. Optimal Monetary Policy with Durable Consumption Goods and Factor Demand Linkages

    DEFF Research Database (Denmark)

    Petrella, Ivan; Santoro, Emiliano

    This paper deals with the implications of factor demand linkages for monetary policy design. We develop a dynamic general equilibrium model with two sectors that produce durable and non-durable goods, respectively. Part of the output produced in each sector is used as an intermediate input of pro...... is crucial, as this does not only influence the user cost of durables through the conventional demand channel, but also affects in opposite directions the real marginal cost of production in either sector through the intermediate input channel.......This paper deals with the implications of factor demand linkages for monetary policy design. We develop a dynamic general equilibrium model with two sectors that produce durable and non-durable goods, respectively. Part of the output produced in each sector is used as an intermediate input......-durable spending in response to a monetary policy shock. A main result of our monetary policy analysis is that strategic complementarities generated by factor demand linkages amplify social welfare loss. As the degree of interconnection between sectors increases, the cost of misperceiving the correct production...

  14. Replenishment policy and inventory optimization for supply-hub with liability period consideration

    Institute of Scientific and Technical Information of China (English)

    李果; 黄焜; 姚琦; 马士华

    2013-01-01

    A replenishment decision-making model for supply-hub is firstly established from the angle of supplier, and optimal replenishment decision of the supplier is analyzed. Then, inventory optimization model for supply-hub is formulated from the angle of the manufacturer, and the optimization algorithm for obtaining optimal inventory levels is given. The result shows that liability period decides the share of the inventory cost between two sides in supply chain. With the increase of liability period, the service level has been quickly reduced even though the manufacturer’s cost has been cut down by transferring the inventory cost to the supplier. As to the safety inventory, if the lower bound of components safety inventory increases, the supplier’s cost will rise up more slowly than the liability period does, while the service levels increases as the safety inventory’s lower bound is raised.

  15. Optimal Mobile Sensing and Actuation Policies in Cyber-physical Systems

    CERN Document Server

    Tricaud, Christophe

    2012-01-01

    A successful cyber-physical system, a complex interweaving of hardware and software in direct interaction with some parts of the physical environment, relies heavily on proper identification of the, often pre-existing, physical elements. Based on information from that process, a bespoke “cyber” part of the system may then be designed for a specific purpose. Optimal Mobile Sensing and Actuation Strategies in Cyber-physical Systems focuses on distributed-parameter systems the dynamics of which can be modelled with partial differential equations. Such systems are very challenging to measure, their states being distributed throughout a spatial domain. Consequently, optimal strategies are needed and systematic approaches to the optimization of sensor locations have to be devised for parameter estimation. The text begins by reviewing the newer field of cyber-physical systems and introducing background notions of distributed parameter systems and optimal observation theory. New research opportunities are then de...

  16. Optimization of two-stage production/inventory systems under order base stock policy with advance demand information

    Science.gov (United States)

    Nakade, Koichi; Yokozawa, Shiori

    2016-08-01

    It is important to share demand information among the members in supply chains. In recent years, production and inventory systems with advance demand information (ADI) have been discussed, where advance demand information means the information of demand which the decision maker obtains before the corresponding actual demand arrives. Appropriate production and inventory control using demand information leads to the decrease of inventory and backlog costs. For a single stage system, the optimal base stock and release lead time have been discussed in the literature. In practical production systems the manufacturing system has multiple processes. The multiple stage production and inventory system with ADI, however, has been analyzed by simulation or assuming exponential processing time. That is, their theoretical analysis and optimization of release lead time and base stock level have little been obtained because of its difficulty. In this paper, theoretical analysis of a two-stage production inventory system with advance demand information is developed, where the processing time is assumed deterministic and identical; demand arrival process is Poisson, and an order base stock policy is adopted. Using the analytical results, optimal release lead time and optimal base stock levels for minimizing the average cost on the holding and backlog costs are explicitly derived.

  17. Replacement model of city bus: A dynamic programming approach

    Science.gov (United States)

    Arifin, Dadang; Yusuf, Edhi

    2017-06-01

    This paper aims to develop a replacement model of city bus vehicles operated in Bandung City. This study is driven from real cases encountered by the Damri Company in the efforts to improve services to the public. The replacement model propounds two policy alternatives: First, to maintain or keep the vehicles, and second is to replace them with new ones taking into account operating costs, revenue, salvage value, and acquisition cost of a new vehicle. A deterministic dynamic programming approach is used to solve the model. The optimization process was heuristically executed using empirical data of Perum Damri. The output of the model is to determine the replacement schedule and the best policy if the vehicle has passed the economic life. Based on the results, the technical life of the bus is approximately 20 years old, while the economic life is an average of 9 (nine) years. It means that after the bus is operated for 9 (nine) years, managers should consider the policy of rejuvenation.

  18. Determination of the optimal periodic maintenance policy under imperfect repair assumption

    OpenAIRE

    Maria Luiza Guerra de Toledo

    2014-01-01

    . An appropriate maintenance policy is essential to reduce expenses and risks related to repairable systems failures. The usual assumptions of minimal or perfect repair at failures are not suitable for many real systems, requiring the application of Imperfect Repair models. In this work, the classes Arithmetic Reduction of Age and Arithmetic Reduction of Intensity, proposed by Doyen and Gaudoin (2004) are explored. Likelihood functions for such models are derived, and the parameters are es...

  19. Value of a noise-optimized virtual monoenergetic reconstruction technique in dual-energy CT for planning of transcatheter aortic valve replacement.

    Science.gov (United States)

    Martin, Simon S; Albrecht, Moritz H; Wichmann, Julian L; Hüsers, Kristina; Scholtz, Jan-Erik; Booz, Christian; Bodelle, Boris; Bauer, Ralf W; Metzger, Sarah C; Vogl, Thomas J; Lehnert, Thomas

    2017-02-01

    To evaluate objective and subjective image quality of a noise-optimized virtual monoenergetic imaging (VMI+) reconstruction technique in dual-energy computed tomography (DECT) angiography prior to transcatheter aortic valve replacement (TAVR). Datasets of 47 patients (35 men; 64.1 ± 10.9 years) who underwent DECT angiography of heart and vascular access prior to TAVR were reconstructed with standard linear blending (F_0.5), VMI+, and traditional monoenergetic (VMI) algorithms in 10-keV intervals from 40-100 keV. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of 564 arterial segments were evaluated. Subjective analysis was rated by three blinded observers using a Likert scale. Mean SNR and CNR were highest in 40 keV VMI+ series (SNR, 27.8 ± 13.0; CNR, 26.3 ± 12.7), significantly (all p VMI series, which showed highest values at 70 keV (SNR, 18.5 ± 7.6; CNR, 16.0 ± 7.4), as well as linearly-blended F_0.5 series (SNR, 16.8 ± 7.3; CNR, 13.6 ± 6.9). Highest subjective image quality scores were observed for 40, 50, and 60 keV VMI+ reconstructions (all p > 0.05), significantly superior to all VMI and standard linearly-blended images (all p VMI+ reconstructions significantly increase CNR and SNR compared to VMI and standard linear-blending image reconstruction and improve subjective image quality in preprocedural DECT angiography in the context of TAVR planning. • VMI+ combines increased contrast with reduced image noise. • VMI+ shows substantially less image noise than traditional VMI. • 40-keV reconstructions show highest SNR/CNR of the aortic and iliofemoral access route. • Observers overall prefer 60 keV VMI+ images. • VMI+ DECT imaging helps improve image quality for TAVR planning.

  20. Optimal core acquisition and remanufacturing policies under uncertain core quality fractions

    NARCIS (Netherlands)

    Teunter, Ruud H.; Flapper, Simme Douwe P.

    2011-01-01

    Cores acquired by a remanufacturer are typically highly variable in quality. Even if the expected fractions of the various quality levels are known, then the exact fractions when acquiring cores are still uncertain. Our model incorporates this uncertainty in determining optimal acquisition decisions

  1. A freight transport optimization model for integrated network, service, and policy design

    NARCIS (Netherlands)

    Zhang, M.; Janic, M.; Tavasszy, L.A.

    2015-01-01

    This paper presents a freight transport optimization model that simultaneously incorporates multimodal infrastructure, hub-based service network structures, and the various design objectives of multiple actors. The model has been calibrated and validated using real-life data from the case study of

  2. Modelling impact of advertising and optimizing advertising policy: an application in recreation

    NARCIS (Netherlands)

    B. Wierenga (Berend)

    1981-01-01

    textabstractThis paper deals with the problem of the desirable level of advertising expenditure, the optimal distribution of this expenditure in time and the allocation over the media: TV, radio and newspaper for a recreation park in the Netherlands. Although the model id developed for the specific

  3. Modelling impact of advertising and optimizing advertising policy: an application in recreation

    NARCIS (Netherlands)

    B. Wierenga (Berend)

    1981-01-01

    textabstractThis paper deals with the problem of the desirable level of advertising expenditure, the optimal distribution of this expenditure in time and the allocation over the media: TV, radio and newspaper for a recreation park in the Netherlands. Although the model id developed for the specific

  4. Dynamic ambulance dispatching: is the closest-idle policy always optimal?

    NARCIS (Netherlands)

    C.J. Jagtenberg (Caroline); S. Bhulai (Sandjai); R.D. van der Mei (Rob)

    2016-01-01

    htmlabstractWe address the problem of ambulance dispatching, in which we must decide which ambulance to send to an incident in real time. In practice, it is commonly believed that the ‘closest idle ambulance’ rule is near-optimal and it is used throughout most literature. In this paper, we present

  5. Optimal Dynamic Investment Policy under Different Rates for Tax Depreciation and Economic Depreciation

    NARCIS (Netherlands)

    Wielhouwer, J.L.; De Waegenaere, A.M.B.; Kort, P.M.

    1999-01-01

    This paper analyzes the consequences of incorporating a different rate for tax depreciation than for economic depreciation. Firms most often choose their tax depreciation rate in a strategic way. It would therefore be a coincidence if this optimization process leads to a tax depreciation rate that e

  6. Optimal Ordering and Pricing Policies for Seasonal Products: Impacts of Demand Uncertainty and Capital Constraint

    Directory of Open Access Journals (Sweden)

    Jinzhao Shi

    2016-01-01

    Full Text Available With a stochastic price-dependent market demand, this paper investigates how demand uncertainty and capital constraint affect retailer’s integrated ordering and pricing policies towards seasonal products. The retailer with capital constraint is normalized to be with zero capital endowment while it can be financed by an external bank. The problems are studied under a low and high demand uncertainty scenario, respectively. Results show that when demand uncertainty level is relatively low, the retailer faced with demand uncertainty always sets a lower price than the riskless one, while its order quantity may be smaller or larger than the riskless retailer’s which depends on the level of market size. When adding a capital constraint, the retailer will strictly prefer a higher price but smaller quantity policy. However, in a high demand uncertainty scenario, the impacts are more intricate. The retailer faced with demand uncertainty will always order a larger quantity than the riskless one if demand uncertainty level is high enough (above a critical value, while the capital-constrained retailer is likely to set a lower price than the well-funded one when demand uncertainty level falls within a specific interval. Therefore, it can be further concluded that the impact of capital constraint on the retailer’s pricing decision can be influenced by different demand uncertainty levels.

  7. An optimal life insurance policy in the investment-consumption problem in an incomplete market

    CERN Document Server

    Egami, Masahiko

    2008-01-01

    This paper considers an optimal life insurance for a householder subject to mortality risk. The household receives a wage income continuously, which is terminated by unexpected (premature) loss of earning power or (planned and intended) retirement, whichever happens first. In order to hedge the risk of losing income stream by householder's unpredictable event, the household enters a life insurance contract by paying a premium to an insurance company. The household may also invest their wealth into a financial market. The problem is to determine an optimal insurance/investment/consumption strategy in order to maximize the expected total, discounted utility from consumption and terminal wealth. To reflect a real-life situation better, we consider an incomplete market where the householder cannot trade insurance contracts continuously. To our best knowledge, such a model is new in the insurance and finance literature. The case of exponential utilities is considered in detail to derive an explicit solution. We al...

  8. Elevator Group-Control Policy Based on Neural Network Optimized by Genetic Algorithm

    Institute of Scientific and Technical Information of China (English)

    SHEN Hong; WAN Jianru; ZHANG Zhichao; LIU Yingpei; LI Guangye

    2009-01-01

    Aiming at the diversity and nonlinearity of the elevator system control target, an effective group method based on a hybrid algorithm of genetic algorithm and neural network is presented in this paper. The genetic algo-rithm is used to search the weight of the neural network. At the same time, the multi-objective-based evaluation function is adopted, in which there are three main indicators including the passenger waiting time, car passengers number and the number of stops. Different weights are given to meet the actual needs. The optimal values of the evaluation function are obtained, and the optimal dispatch control of the elevator group control system based on neural network is realized. By analyzing the running of the elevator group control system, all the processes and steps are presented. The validity of the hybrid algorithm is verified by the dynamic imitation performance.

  9. Optimal design for inspection and maintenance policy based on the CCC chart

    OpenAIRE

    Chan, Ling-Yau; Wu, Shaomin

    2009-01-01

    In this paper, the concept of cumulative count of conforming chart (CCC chart) is applied in inspection and maintenance planning for systems where minor inspection, major inspection, minor maintenance and major maintenance are available. Several inspection and maintenance plans are defined and studied quantitatively. Analytic expressions of relevant statistics and their expectations are derived. These inspection and maintenance plans are optimized from an economic consideration.

  10. A STUDY ON THE OPTIMAL EXPLOITATION POLICY OF MULTI-MINE RESOURCES

    Institute of Scientific and Technical Information of China (English)

    魏晓平; 王立杰

    1997-01-01

    At the present stage, the exploitation loss and waste of mineral resources are serious. If this trend goes on, it will undoubtedly accelerate the resource depletion. Based on the values of mineral resources and their natural and economic attibutes, this paper sets up a multi-mine mineral resource exploitation model in the market competition. In addition, it analyses the structure of the model and derives optimal conditions. Finally it gives a detailed interpretation of the practical application of the model for instance.

  11. Controlling measles using supplemental immunization activities: A mathematical model to inform optimal policy

    OpenAIRE

    Verguet, Stéphane; Johri, Mira; Morris, Shaun K; Gauvreau, Cindy L.; Jha, Prabhat; Jit, Mark

    2015-01-01

    Background The Measles & Rubella Initiative, a broad consortium of global health agencies, has provided support to measles-burdened countries, focusing on sustaining high coverage of routine immunization of children and supplementing it with a second dose opportunity for measles vaccine through supplemental immunization activities (SIAs). We estimate optimal scheduling of SIAs in countries with the highest measles burden. Methods We develop an age-stratified dynamic compartmental model of mea...

  12. GROUP-BUYING ONLINE AUCTION AND OPTIMAL INVENTORY POLICY IN UNCERTAIN MARKET

    Institute of Scientific and Technical Information of China (English)

    Jian CHEN; Yunhui LIU; Xiping SONG

    2004-01-01

    In this paper we consider a group-buying online auction (GBA) model for a monopolistic manufacturer selling novel products in the uncertain market. Firstly, we introduce the bidder's dominant strategy, after which we optimize the GBA price curve and the production volume together.Finally, we compare the GBA with the traditional posted pricing mechanism and find that the GBA is highly probable to be advantageous over the posted pricing mechanism in some appropriate market environments.

  13. Throughput Optimal Policies for Energy Harvesting Wireless Transmitters with Non-Ideal Circuit Power

    CERN Document Server

    Xu, Jie

    2012-01-01

    Characterizing the fundamental tradeoffs for maximizing energy efficiency (EE) versus spectrum efficiency (SE) is a key problem in wireless communication. In this paper, we address this problem for a point-to-point additive white Gaussian noise (AWGN) channel with the transmitter powered solely via energy harvesting from the environment. In addition, we assume a practical on-off transmitter model with non-ideal circuit power, i.e., when the transmitter is on, its consumed power is the sum of the transmit power and a constant circuit power. Under this setup, we study the optimal transmit power allocation to maximize the average throughput over a finite horizon, subject to the time-varying energy constraint and the non-ideal circuit power consumption. First, we consider the off-line optimization under the assumption that the energy arrival time and amount are a priori known at the transmitter. Although this problem is non-convex due to the non-ideal circuit power, we show an efficient optimal solution that in g...

  14. The optimal retailer's ordering policies with trade credit financing and limited storage capacity in the supply chain system

    Science.gov (United States)

    Yen, Ghi-Feng; Chung, Kun-Jen; Chen, Tzung-Ching

    2012-11-01

    The traditional economic order quantity model assumes that the retailer's storage capacity is unlimited. However, as we all know, the capacity of any warehouse is limited. In practice, there usually exist various factors that induce the decision-maker of the inventory system to order more items than can be held in his/her own warehouse. Therefore, for the decision-maker, it is very practical to determine whether or not to rent other warehouses. In this article, we try to incorporate two levels of trade credit and two separate warehouses (own warehouse and rented warehouse) to establish a new inventory model to help the decision-maker to make the decision. Four theorems are provided to determine the optimal cycle time to generalise some existing articles. Finally, the sensitivity analysis is executed to investigate the effects of the various parameters on ordering policies and annual costs of the inventory system.

  15. The optimal replenishment policy for time-varying stochastic demand under vendor managed inventory

    DEFF Research Database (Denmark)

    Govindan, Kannan

    2015-01-01

    A Vendor Managed Inventory (VMI) partnership places the responsibility on the vendor (rather than on buyers) to schedule purchase orders for inventory replenishment in the supply chain system. In this research, the supply chain network considers the Silver-Meal heuristic with an augmentation...... quantity replenishment policy between both traditional and VMI systems. We consider time-varying stochastic demand in two-echelon (one vendor, multiple retailers) supply chains. This paper seeks to find the supply chain that minimizes system cost through comparing performance between traditional and VMI...... systems. A mathematical model is developed, and total supply chain cost is used as the measure of comparison. The models are applied in both traditional and VMI supply chains based on pharmaceutical industry data, and we focus on total cost difference compared through the use of Adjusted Silver-Meal (ASM...

  16. The optimal replenishment policy for time-varying stochastic demand under vendor managed inventory

    DEFF Research Database (Denmark)

    Govindan, Kannan

    2015-01-01

    A Vendor Managed Inventory (VMI) partnership places the responsibility on the vendor (rather than on buyers) to schedule purchase orders for inventory replenishment in the supply chain system. In this research, the supply chain network considers the Silver-Meal heuristic with an augmentation...... quantity replenishment policy between both traditional and VMI systems. We consider time-varying stochastic demand in two-echelon (one vendor, multiple retailers) supply chains. This paper seeks to find the supply chain that minimizes system cost through comparing performance between traditional and VMI...... systems. A mathematical model is developed, and total supply chain cost is used as the measure of comparison. The models are applied in both traditional and VMI supply chains based on pharmaceutical industry data, and we focus on total cost difference compared through the use of Adjusted Silver-Meal (ASM...

  17. An analysis of the feasibility of carbon management policies as a mechanism to influence water conservation using optimization methods.

    Science.gov (United States)

    Wright, Andrew; Hudson, Darren

    2014-10-01

    Studies of how carbon reduction policies would affect agricultural production have found that there is a connection between carbon emissions and irrigation. Using county level data we develop an optimization model that accounts for the gross carbon emitted during the production process to evaluate how carbon reducing policies applied to agriculture would affect the choices of what to plant and how much to irrigate by producers on the Texas High Plains. Carbon emissions were calculated using carbon equivalent (CE) calculations developed by researchers at the University of Arkansas. Carbon reduction was achieved in the model through a constraint, a tax, or a subsidy. Reducing carbon emissions by 15% resulted in a significant reduction in the amount of water applied to a crop; however, planted acreage changed very little due to a lack of feasible alternative crops. The results show that applying carbon restrictions to agriculture may have important implications for production choices in areas that depend on groundwater resources for agricultural production. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Newton method for determining the optimal replenishment policy for EPQ model with present value

    Directory of Open Access Journals (Sweden)

    Wu Kuo-Jung Jeff

    2008-01-01

    Full Text Available This paper is a response for the paper of Dohi, Kaio and Osaki, that was published in RAIRO: Operations Research, 26, 1-14 (1992 for an EPQ model with present value. The purpose of this paper is threefold. First, the convex and increasing properties for the first derivative of the objective function are proved. Second, we apply the Newton method to find the optimal cycle time. Third, we provide some numerical examples to demonstrate that the Newton method is more efficient than the bisection method. .

  19. Optimal replenishment and credit policy in supply chain inventory model under two levels of trade credit with time- and credit-sensitive demand involving default risk

    Science.gov (United States)

    Mahata, Puspita; Mahata, Gour Chandra; Kumar De, Sujit

    2017-06-01

    Traditional supply chain inventory modes with trade credit usually only assumed that the up-stream suppliers offered the down-stream retailers a fixed credit period. However, in practice the retailers will also provide a credit period to customers to promote the market competition. In this paper, we formulate an optimal supply chain inventory model under two levels of trade credit policy with default risk consideration. Here, the demand is assumed to be credit-sensitive and increasing function of time. The major objective is to determine the retailer's optimal credit period and cycle time such that the total profit per unit time is maximized. The existence and uniqueness of the optimal solution to the presented model are examined, and an easy method is also shown to find the optimal inventory policies of the considered problem. Finally, numerical examples and sensitive analysis are presented to illustrate the developed model and to provide some managerial insights.

  20. Intergenerational photovoice projects: optimizing this mechanism for influencing health promotion policies and strengthening relationships.

    Science.gov (United States)

    Garcia, Carolyn M; Aguilera-Guzman, Rosa Maria; Lindgren, Sandi; Gutierrez, Rodolfo; Raniolo, Blanca; Genis, Therese; Vazquez-Benitez, Gabriela; Clausen, Lisa

    2013-09-01

    Intergenerational photovoice groups are promising for promoting health through the topic that is explored and through group dynamics that can foster healthy relationships and communication. To investigate the potential benefits of intergenerational photovoice projects, photovoice groups were conducted in urban Minnesota, United States, and in rural Morelos, Mexico, between 2009 and 2012 with Mexican-origin adults and their adolescent relatives. Seven photovoice groups of adult-adolescent dyads met for eight sessions and developed exhibits highlighting their views on health and migration and made policy recommendations, using messages conveyed through their words and photographs. Informal process evaluation and focus groups were used to elicit feedback about photovoice project participation. Photovoice project themes were descriptively analyzed. Focus group evaluation data were thematically summarized, and facilitator reflections were descriptively summarized to identify factors associated with intergenerational photovoice groups. Seventy-five participants were recruited. Photovoice themes represented effects of migration on health, family, and well-being. The following two evaluative themes were identified: (a) participant sentiments about the benefits of photovoice participation and (b) facilitator observations of intergenerational photovoice group benefits and challenges. Participants described opportunities to learn new things and barriers to healthy relationships that the project was eliminating by providing them with time to work together. Used in health promotion, photovoice is a valuable tool that contributes to understanding the complex underlying factors influencing behaviors and health.

  1. Retailer's optimal policy under inflation in fuzzy environment with trade credit

    Science.gov (United States)

    Yadav, Dharmendra; Singh, S. R.; Kumari, Rachna

    2015-03-01

    Trade credit plays an important role in financing many industries. In the classical inventory model it is assumed that the buyer must pay for the items as soon as the items are received. In this problem, it is considered that the retailer can pay the supplier either at the end of the credit period or later pay interest on the unpaid amount for the overdue period. Here, the retailer's inventory model for the optimal cycle time and payment time for a retailer is developed. The effects of the inflation rate, deterioration rate and delay in payment have been discussed. The whole study is performed in a fuzzy environment by taking the opportunity cost, interest earned and interest paid rate as a triangular fuzzy number. Fuzzy profit functions, which involve fuzzy arithmetic operation, are defined using the function principle. We use the signed distance method to defuzzify the fuzzy profit function. Moreover, numerical and sensitivity analysis is performed to validate the proposed model.

  2. Optimal operating policy for a controllable queueing model with a fuzzy environment

    Institute of Scientific and Technical Information of China (English)

    Chuen-homg LIN; Jau-chuan KE

    2009-01-01

    We construct the membership functions of the fuzzy objective values of a controllable queueing model, in which cost elements, arrival rate and service rate are all fuzzy numbers. Based on Zadeh's extension principle, a set of parametric nonlinear programs is developed to find the upper and lower bounds of the minimal average total cost per unit time at the possibility level. The membership functions of the minimal average total cost are further constructed using different values of the possibility level. A numerical example is solved successfully to illustrate the validity of the proposed approach. Because the object value is ex-pressed and governed by the membership functions, the optimization problem in a fuzzy environment for the controllable queueing models is represented more accurately and analytical results are more useful for system designers and practitioners.

  3. Retailer’s optimal ordering policies for EOQ model with imperfective items under a temporary discount

    Directory of Open Access Journals (Sweden)

    Lin Wen Feng

    2016-01-01

    Full Text Available In this article, we study inventory models to determine the optimal special order and maximum saving cost of imperfective items when the supplier offers a temporary discount. The received items are not all perfect and the defectives can be screened out by the end of 100% screening process. Three models are considered according to the special order occurs at regular replenishment time, non-regular replenishment time, and screening time of economic order quantity cycle. Each model has two sub-cases to be discussed. In temporary discount problems, in general, there are integer operators in objective functions. We suggest theorems to find the closed-form solutions to these kinds of problems. Furthermore, numerical examples and sensitivity analysis are given to illustrate the results of the proposed properties and theorems.

  4. Optimal Ordering and Disposing Policies in the Presence of an Overconfident Retailer: A Stackelberg Game

    Directory of Open Access Journals (Sweden)

    Zhigang Wang

    2015-01-01

    Full Text Available This paper investigates the impact of the retailer’s overconfident behavior on supply chain performance. We start with a basic model on the rational newsvendor model and investigate the retailer’s optimal ordering decision and expected profit. Next, we extend the basic model and introduce an overconfident retailer. We find that the retailer’s overconfident behavior does not necessarily damage the supply chain compared with the basic model when the overconfident level does not exceed a threshold. We also design the cooperation and buyback mechanism and conduct numerical analysis to compare the manufacturer’s and retailer’s expected profits and real profits with those in the basic newsvendor model. It can achieve Pareto improvement in the supply chain when the overconfident level is low. When the retailer’s overconfident level exceeds a threshold, the retailer’s ordering decision cannot make the whole supply chain sustainable development.

  5. Necessary and Sufficient Conditions for Pareto Optimality in Infinite Horizon Cooperative Differential Games - Replaced by CentER DP 2011-041

    NARCIS (Netherlands)

    Reddy, P.V.; Engwerda, J.C.

    2010-01-01

    In this article we derive necessary and sufficient conditions for the existence of Pareto optimal solutions for an N player cooperative infinite horizon differential game. Firstly, we write the problem of finding Pareto candidates as solving N constrained optimal control subproblems. We derive some

  6. The Deterministic Impulse Control Maximum Principle in Operations Research : Necessary and Sufficient Optimality Conditions (replaces CentER DP 2011-052)

    NARCIS (Netherlands)

    Chahim, M.; Hartl, R.F.; Kort, P.M.

    2011-01-01

    This paper considers a class of optimal control problems that allows jumps in the state variable. We present the necessary optimality conditions of the Impulse Control Maximum Principle based on the current value formulation. By reviewing the existing impulse control models in the literature, we poi

  7. Optimal policies for activated sludge treatment systems with multi effluent stream generation

    Directory of Open Access Journals (Sweden)

    Gouveia R.

    2000-01-01

    Full Text Available Most industrial processes generate liquid waste, which requires treatment prior to disposal. These processes are divided into sectors that generate effluents with time dependent characteristics. Each sector sends the effluent to wastewater treatment plants through pumping-stations. In general, activated sludge is the most suitable treatment and consists of equalization, aeration and settling tanks. During the treatment, there is an increase in the mass of microorganisms, which needs to be removed. Sludge removal represents the major operating costs for wastewater treatment plants. The objective of this work is to propose an optimization model to minimize sludge generation using a superstructure in which the streams from pumping-stations can be sent to the equalization tank. In addition, the aeration tank is divided into cells that can be fed in series and parallel. The model relies on mass balances, kinetic equations, and the resulting Nonlinear Programming problem generates the best operational strategy for the system feed streams with a high substrate removal. Reductions of up to 30 % can be achieved with the proposed strategy maintened BOD efficiency removal upper than 98 %.

  8. On the Optimal Policy for the Single-product Inventory Problem with Set-up Cost and a Restricted Production Capacity

    NARCIS (Netherlands)

    Foreest, N. D. van; Wijngaard, J.

    2010-01-01

    The single-product, stationary inventory problem with set-up cost is one of the classical problems in stochastic operations research. Theories have been developed to cope with finite production capacity in periodic review systems, and it has been proved that optimal policies for these cases are not

  9. [Estrogen replacement].

    Science.gov (United States)

    Søgaard, A J; Berntsen, G K; Magnus, J H; Tollan, A

    1998-02-10

    Recent research on long-term postmenopausal hormone replacement therapy (HRT) indicates a positive effect on both total mortality and morbidity. This has raised the question of widespread preventive long-term use of HRT. Possible side-effects and ideological issues related to preventive HRT have led to debate and uncertainty among health professionals, in the media, and in the population at large. In order to evaluate the level of knowledge about and attitudes towards HRT, a randomly selected group of 737 Norwegian women aged 16-79 was interviewed by the Central Bureau of Statistics. One in three women had received information about HRT in the last two years, mainly through weekly magazines and physicians. The proportion who answered the questions on knowledge correctly varied from 36% to 47%. Those who had been given information by a physician possessed accurate knowledge, had more positive attitudes towards HRT and were more willing to use HRT than women who had reviewed information through other channels. Women with a higher level of education were better informed and more knowledgeable than others, but were nevertheless more reluctant to use HRT than those who were less educated. The limited number of women who actually receive information on HRT, the low level of knowledge and the ambivalent attitudes toward HRT are a major challenge to the public health service.

  10. Optimism

    Science.gov (United States)

    Carver, Charles S.; Scheier, Michael F.; Segerstrom, Suzanne C.

    2010-01-01

    Optimism is an individual difference variable that reflects the extent to which people hold generalized favorable expectancies for their future. Higher levels of optimism have been related prospectively to better subjective well-being in times of adversity or difficulty (i.e., controlling for previous well-being). Consistent with such findings, optimism has been linked to higher levels of engagement coping and lower levels of avoidance, or disengagement, coping. There is evidence that optimism is associated with taking proactive steps to protect one's health, whereas pessimism is associated with health-damaging behaviors. Consistent with such findings, optimism is also related to indicators of better physical health. The energetic, task-focused approach that optimists take to goals also relates to benefits in the socioeconomic world. Some evidence suggests that optimism relates to more persistence in educational efforts and to higher later income. Optimists also appear to fare better than pessimists in relationships. Although there are instances in which optimism fails to convey an advantage, and instances in which it may convey a disadvantage, those instances are relatively rare. In sum, the behavioral patterns of optimists appear to provide models of living for others to learn from. PMID:20170998

  11. A Global Optimizing Policy for Decaying Items with Ramp-Type Demand Rate under Two-Level Trade Credit Financing Taking Account of Preservation Technology

    Directory of Open Access Journals (Sweden)

    S. R. Singh

    2013-01-01

    Full Text Available An inventory system for deteriorating items, with ramp-type demand rate, under two-level trade credit policy taking account of preservation technology is considered. The objective of this study is to develop a deteriorating inventory policy when the supplier provides to the retailer a permissible delay in payments, and during this credit period, the retailer accumulates the revenue and earns interest on that revenue; also the retailer invests on the preservation technology to reduce the rate of product deterioration. Shortages are allowed and partially backlogged. Sufficient conditions of the existence and uniqueness of the optimal replenishment policy are provided, and an algorithm, for its determination, is proposed. Numerical examples draw attention to the obtained results, and the sensitivity analysis of the optimal solution with respect to leading parameters of the system is carried out.

  12. Optimization

    CERN Document Server

    Pearce, Charles

    2009-01-01

    Focuses on mathematical structure, and on real-world applications. This book includes developments in several optimization-related topics such as decision theory, linear programming, turnpike theory, duality theory, convex analysis, and queuing theory.

  13. Minimally Invasive Transcatheter Aortic Valve Replacement (TAVR)

    Medline Plus

    Full Text Available Watch a Broward Health surgeon perform a minimally invasive Transcatheter Aortic Valve Replacement (TAVR) Click Here to view the BroadcastMed, Inc. Privacy Policy and Legal Notice © 2017 BroadcastMed, Inc. ...

  14. Minimally Invasive Transcatheter Aortic Valve Replacement (TAVR)

    Medline Plus

    Full Text Available Watch a Broward Health surgeon perform a minimally invasive Transcatheter Aortic Valve Replacement (TAVR) Click Here to view the BroadcastMed, Inc. Privacy Policy and Legal Notice © 2017 BroadcastMed, Inc. ...

  15. Maintenance overtime policies in reliability theory models with random working cycles

    CERN Document Server

    Nakagawa, Toshio

    2015-01-01

    This book introduces a new concept of replacement in maintenance and reliability theory. Replacement overtime, where replacement occurs at the first completion of a working cycle over a planned time, is a new research topic in maintenance theory and also serves to provide a fresh optimization technique in reliability engineering. In comparing replacement overtime with standard and random replacement techniques theoretically and numerically, 'Maintenance Overtime Policies in Reliability Theory' highlights the key benefits to be gained by adopting this new approach and shows how they can be applied to inspection policies, parallel systems and cumulative damage models. Utilizing the latest research in replacement overtime by internationally recognized experts, readers are introduced to new topics and methods, and learn how to practically apply this knowledge to actual reliability models. This book will serve as an essential guide to a new subject of study for graduate students and researchers and also provides a...

  16. Cache Replacement Policy of Mobile Instant Messaging Application%移动即时通讯软件的缓存替换策略

    Institute of Scientific and Technical Information of China (English)

    王文博; 王菁; 邢起源; 韩燕波

    2015-01-01

    Recently, the function of mobile instant messaging application is becoming more and more complex, mean-while, the size of data recordings is also becoming bigger and bigger. As a consequence, this situation has brought great pressure to the limited space of mobile terminals. To cope with the above problem, this paper studies and analyzes different user gesture on different parts of the mobile instant messaging application, and then explores the relation between user gesture and the value of cache blocks. This paper also proposes a strategy based on user gesture to manage the cache of mobile instant messaging application accordingly, and points at the value of each block of cache data for user replacing cache blocks. This strategy is capable of adapting to the characteristics of mobile termi-nals with relatively small memory, low bandwidth and high timeliness requirements of instant messaging software.Through the experiments, the proposed strategy has high hit rate and can hold the cache size of mobile instant messaging application.%近年来,移动即时通讯软件功能越来越多样化,其聊天记录等数据的规模也越来越大,这给本身空间有限的移动终端的存储和处理带来很大压力。为了解决以上问题,研究和分析了移动即时通讯软件中针对不同部分的聊天记录用户的行为特点,进而探究了用户行为和缓存价值之间的联系,提出了一种基于用户浏览行为的缓存替换策略,针对每部分缓存的数据对用户的价值有选择地替换记录缓存。该策略可以很好地适应移动终端小内存、低带宽和即时通讯软件高时效性等要求。实验证明,所提策略具有较高的缓存命中率,且可有效控制即时通讯软件的缓存大小。

  17. Optimal Implantation Depth and Adherence to Guidelines on Permanent Pacing to Improve the Results of Transcatheter Aortic Valve Replacement With the Medtronic CoreValve System: The CoreValve Prospective, International, Post-Market ADVANCE-II Study.

    Science.gov (United States)

    Petronio, Anna S; Sinning, Jan-Malte; Van Mieghem, Nicolas; Zucchelli, Giulio; Nickenig, Georg; Bekeredjian, Raffi; Bosmans, Johan; Bedogni, Francesco; Branny, Marian; Stangl, Karl; Kovac, Jan; Schiltgen, Molly; Kraus, Stacia; de Jaegere, Peter

    2015-05-01

    The aim of the CoreValve prospective, international, post-market ADVANCE-II study was to define the rates of conduction disturbances and permanent pacemaker implantation (PPI) after transcatheter aortic valve replacement with the Medtronic CoreValve System (Minneapolis, Minnesota) using optimized implantation techniques and application of international guidelines on cardiac pacing. Conduction disturbances are a frequent complication of transcatheter aortic valve replacement. The rates of PPI in the published reports vary according to bioprosthesis type and the indications for PPI. The primary endpoint was the 30-day incidence of PPI with Class I/II indications when the Medtronic CoreValve System was implanted at an optimal depth (≤6 mm below the aortic annulus). The timing and resolution of all new-onset conduction disturbances were analyzed. A total of 194 patients were treated. The overall rate of PPI for Class I/II indications was 18.2%. An optimal depth was reached in 43.2% of patients, with a nonsignificantly lower incidence of PPI in patients with depths ≤6 mm, compared with those with deeper implants (13.3% vs. 21.1%; p = 0.14). In a paired analysis, new-onset left bundle branch block and first-degree atrioventricular block occurred in 45.4% and 39.0% of patients, respectively, and resolved spontaneously within 30 days in 43.2% and 73.9%, respectively. In patients with new PPI, the rate of intrinsic sinus rhythm increased from 25.9% at 7 days to 59.3% at 30 days (p = 0.004). Optimal Medtronic CoreValve System deployment and adherence to international guidelines on cardiac pacing are associated with a lower rate of new PPI after transcatheter aortic valve replacement, compared with results reported in previous studies. (CoreValve Advance-II Study: Prospective International Post-Market Study [ADVANCE II]; NCT01624870). Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  18. Optimal policy for profit maximising in an EOQ model under non-linear holding cost and stock-dependent demand rate

    Science.gov (United States)

    Pando, V.; García-Laguna, J.; San-José, L. A.

    2012-11-01

    In this article, we integrate a non-linear holding cost with a stock-dependent demand rate in a maximising profit per unit time model, extending several inventory models studied by other authors. After giving the mathematical formulation of the inventory system, we prove the existence and uniqueness of the optimal policy. Relying on this result, we can obtain the optimal solution using different numerical algorithms. Moreover, we provide a necessary and sufficient condition to determine whether a system is profitable, and we establish a rule to check when a given order quantity is the optimal lot size of the inventory model. The results are illustrated through numerical examples and the sensitivity of the optimal solution with respect to changes in some values of the parameters is assessed.

  19. Policy and Power : a conceptual framework between the 'old' and 'new' policy idioms

    NARCIS (Netherlands)

    Arts, B.J.M.; Tatenhove, van J.

    2004-01-01

    During the last few decades, both policy practices and policy idioms have drastically changed. Concepts such as interactive planning, network management, stakeholder dialogue, deliberative democracy, policy discourses, governance, etc. have replaced older ones such as public administration, policy p

  20. Analysis of"Business Tax Replaced by Value-added Tax"Policy's Impact on Construction Project%浅析“营改增”对建筑工程项目的影响

    Institute of Scientific and Technical Information of China (English)

    刘姁

    2015-01-01

    "Business Tax Replaced by Value-added Tax"policy is one of the important measures in perfecting the tax sys⁃tem structure, the smooth implementation of this policy also has an important positive significance for the construction in⁃dustry: namely effectively solving the double taxation problem, being conducive to the technological transformation and equipment renewal, and helpful to improve professional ability. However, due to such problems as"providing material by owner", sporadic materials, labor costs, rental fees, cost of raw materials and etc., there used to be a greater difference be⁃tween the actual tax burden and ideal state, and the positive significance of this policy could not be fully played. As for this, the enterprise can choose appropriate time to update the fixed assets, improve the level of modernization, and then raise the core competitiveness of the enterprise;at the same time seize the opportunity and combine with reality to con⁃duct effective tax planning, reduce tax burden as far as possible, actively participate in the long term or short term invest⁃ment, so as to further enhance the profitability.%“营改增”是完善税制结构的重要措施,其顺利实施对建筑行业也有着重要的积极意义:可有效解决重复征税,有利于技术改造和设备更新,有助于提升专业能力。但是,由于“甲供材”、零星材料、人工费、租赁费、材料费等问题,实际税负与理想状态差别较大,积极意义也大打折扣。对此,企业可选择恰当时机适时更新固定资产,提高现代化水平,进而提升企业的核心竞争力;抓住机遇结合实际进行有效的税收筹划,尽可能降低税负,积极参与长线或短线投资,进一步提升盈利能力。

  1. Optimal policies for simultaneous energy consumption and ancillary service provision for flexible loads under stochastic prices and no capacity reservation constraint

    Science.gov (United States)

    Kefayati, Mahdi; Baldick, Ross

    2015-07-01

    Flexible loads, i.e. the loads whose power trajectory is not bound to a specific one, constitute a sizable portion of current and future electric demand. This flexibility can be used to improve the performance of the grid, should the right incentives be in place. In this paper, we consider the optimal decision making problem faced by a flexible load, demanding a certain amount of energy over its availability period, subject to rate constraints. The load is also capable of providing ancillary services (AS) by decreasing or increasing its consumption in response to signals from the independent system operator (ISO). Under arbitrarily distributed and correlated Markovian energy and AS prices, we obtain the optimal policy for minimising expected total cost, which includes cost of energy and benefits from AS provision, assuming no capacity reservation requirement for AS provision. We also prove that the optimal policy has a multi-threshold form and can be computed, stored and operated efficiently. We further study the effectiveness of our proposed optimal policy and its impact on the grid. We show that, while optimal simultaneous consumption and AS provision under real-time stochastic prices are achievable with acceptable computational burden, the impact of adopting such real-time pricing schemes on the network might not be as good as suggested by the majority of the existing literature. In fact, we show that such price responsive loads are likely to induce peak-to-average ratios much more than what is observed in the current distribution networks and adversely affect the grid.

  2. Optimal diagnostic measures and thresholds for hypogonadism in men with HIV/AIDS: comparison between 2 transdermal testosterone replacement therapy gels.

    Science.gov (United States)

    Blick, Gary

    2013-03-01

    To determine the incidence of hypogonadism in men with human immunodeficiency virus (HIV)/acquired immunodeficiency virus (AIDS), the most useful serum testosterone measurement and threshold for diagnosing hypogonadism, and the comparative efficacy of 2 testosterone replacement therapy (TRT) 1% gels (AndroGel® [Abbott Laboratories] and Testim® [Auxilium Pharmaceuticals, Inc.]). This was a 2-stage observational study. In stage 1, patient records from 2 medical practices specializing in HIV/AIDS were reviewed. Eligible patients were aged ≥ 18 years; had HIV-seropositive status confirmed by enzyme-linked immunosorbent assay and western blot test or HIV-1 viremia confirmed by HIV-1 RNA polymerase chain reaction; and had prior baseline testosterone assessments for hypogonadism (ie, presence of signs/symptoms of hypogonadism as well as total testosterone [TT] and free testosterone [FT] level measurements). Stage 2 included the evaluation of patients from stage 1 who were treated with 5 to 10 g/day of TRT. The stage 2 inclusion criteria were a diagnosis of low testosterone (defined as TT level testosterone level therapy due to adverse events. The most useful serum testosterone measurement and threshold for diagnosing hypogonadism in men with HIV/AIDS was FT level < 100 pg/mL, which identified 64% of men as hypogonadal with the presence of ≥ 1 hypogonadal symptom. This is above currently accepted thresholds. Criteria using TT level < 300 ng/dL and FT level < 50 pg/mL only diagnosed 24% and 19% of patients, respectively, as having hypogonadism. Testim® was more effective than AndroGel® in increasing TT and FT levels and improving hypogonadal symptoms.

  3. Optimal Acquisition and Production Policy for End-of-Life Engineering Machinery Recovering in a Joint Manufacturing/Remanufacturing System under Uncertainties in Procurement and Demand

    Directory of Open Access Journals (Sweden)

    Haolan Liao

    2017-02-01

    Full Text Available The intensive shortage of natural resources and the inchoate phase of automobile remanufacturing in a closed-loop supply chain (CLSC are driving people to take cyclic manufacturing seriously. Aiming at maximizing resource utilization and produce profits, we apply an optimizing mathematical analysis to the modeling of automobile engine remanufacturing in a joint manufacturing system, in which the quantity and quality of procurement, and the demand of the market, are both uncertain. The manufacturer can either produce new products with raw materials or remanufacture the returned product taken back from customers; the raw materials are bought from two suppliers with certain probabilities of disruption in the supply. The returned products are classified into different quality levels according to the testing results after sorting, by considering the remanufacture-up-to strategy we obtained the optimal remanufacturing ratio, then the manufacturing quantity and corresponding maximized total profit of this joint system are determined. We also investigated a real-life case of auto engine remanufacturing, comparing it with the theory of optimal remanufacturing policy, and the results indicate that a material savings of more than 45% and a cost improvement of more than 40% could be achieved when the optimal remanufacturing policy of our model is implemented.

  4. Optimal premium policy of an insurance firm with stochastic interest rates%随机利率下保险公司最优保费策略

    Institute of Scientific and Technical Information of China (English)

    孟祥波; 张立东; 杜子平

    2013-01-01

    研究了随机利率下保险公司所面临的最优化问题.决策者可以通过调节保费费率来控制其现金余额过程.在给出预定目标水平的前提下,通过最小化现金余额过程中的总偏差,得到了最优保费策略及最优成本函数.%The optimization problem was studied which an insurance firm faced under the stochastic interest rates. The decision-makers can control its cash-balance dynamics by adjusting the underlying premium rate. The firm' s objective is to minimize the total deviation of its cash-balance process. Thus the optimal premium policy and the optimal cost function were obtained.

  5. An Economic and Environmental Assessment Model for Selecting the Optimal Implementation Strategy of Fuel Cell Systems—A Focus on Building Energy Policy

    Directory of Open Access Journals (Sweden)

    Daeho Kim

    2014-08-01

    Full Text Available Considerable effort is being made to reduce the primary energy consumption in buildings. As part of this effort, fuel cell systems are attracting attention as a new/renewable energy systems for several reasons: (i distributed generation system; (ii combined heat and power system; and (iii availability of various sources of hydrogen in the future. Therefore, this study aimed to develop an economic and environmental assessment model for selecting the optimal implementation strategy of the fuel cell system, focusing on building energy policy. This study selected two types of buildings (i.e., residential buildings and non-residential buildings as the target buildings and considered two types of building energy policies (i.e., the standard of energy cost calculation and the standard of a government subsidy. This study established the optimal implementation strategy of the fuel cell system in terms of the life cycle cost and life cycle CO2 emissions. For the residential building, it is recommended that the subsidy level and the system marginal price level be increased. For the non-residential building, it is recommended that gas energy cost be decreased and the system marginal price level be increased. The developed model could be applied to any other country or any other type of building according to building energy policy.

  6. Optimal Investment-consumption Policies Selection for Heston Model%Heston模型下最优投资-消费策略选择

    Institute of Scientific and Technical Information of China (English)

    杨鹏

    2016-01-01

    The optimal investment-consumption policies selection problems were studied with stochastic financial market. In stochastic financial market, assets are composed of risk-free and risky asset, and the volatility of the risky asset was described by a Heston model. Optimal investment-consumption policies which maximize the expected discounted utility of terminal wealth and accumulative consumption was found. By solving the corresponding Hamilton-Jacobi-Bellman ( HJB) equation, closed-form solutions for the value function as well as the investment-consumption policies in the power utility function case are ob-tained.%在随机金融市场模型中,研究了最优投资-消费策略选择问题。随机金融市场由无风险资产和风险资产构成,在风险资产的方差满足Heston模型下,求得最优投资-消费策略最大化终端财富和累积消费的期望折现效用。在幂效用函数情形下,通过求解值函数满足的Hamilton-Jacobi-Bellman ( HJB)方程,得到了最优投资-消费策略以及值函数的显式解。

  7. Financial Stability, Target Inflation as a Monetary Rule and Concepts of Money Policy: Implications for the Optimal Analysis

    Directory of Open Access Journals (Sweden)

    Mohsen Brahmi

    2015-04-01

    Full Text Available In this article, basing on offensive lecturing research articles of famous authors on financial instability and monetary policy, we propose as aim of this paper to discuss the controversial rule vs. discretion in monetary policy and the new institutional framework of inflation targeting as a remedy for inflationary pressures after the cause of the intermediate target of monetary anchors and exchange rate policy, since the year 70's of the last Century. To do this, we treated a literature review in the field, assigning the work of various economists thus handling of monetary policy favors the discretion/rule to the new inflation target strategy in 90's and 2000. We put particular emphasis on the second step of this paper on the possibility of inflation targeting as an anti-inflationary objective defended for its main defendants.

  8. Economic and environmental multi-objective optimization to evaluate the impact of Belgian policy on solar power and electric vehicles

    OpenAIRE

    De Schepper, Ellen; Van Passel, Steven; Lizin, Sebastien; Vincent, Thomas; Martin, Benjamin; Gandibleux, Xavier

    2015-01-01

    This research uses multi-objective optimization to determine the optimal mixture of energy and transportation technologies, while optimizing economic and environmental impacts. We demonstrate the added value of using multi-objective mixed integer linear programming (MOMILP) considering economies of scale versus using continuous multi-objective linear programming (MOLP) assuming average cost intervals. This paper uses an improved version to solve MOMILPs exactly (Vincent, et al. 2013). To diff...

  9. Monetary Policy and Economic Policy

    Directory of Open Access Journals (Sweden)

    Iordachioaia Adelina-Geanina

    2011-02-01

    Full Text Available There is widespread agreement that monetary policy matters,but there is disagreement about how it should be conducted. Behind this disagreement lie differences in theoretical understandings. The paper contrasts the New Classical, Neo-Keynesian, and Post-Keynesian frameworks, there by surfacing the differences. The New Classical model has policy only affecting long run inflation. The Neo-Keynesian has policy impacting inflation, unemployment, and real wages. The Post-Keynesian model also impacts growth, so policy implicitly picks a quadruple. Inflation targeting is a sub-optimal policy frame because it biases decisions toward low inflation by obscuring the fact that policy also affects unemployment, real wages, and growth.

  10. NitroGenius: a nitrogen decision support system. A game to develop the optimal policy to solve the Dutch nitrogen pollution problem.

    Science.gov (United States)

    Erisman, Jan Willem; Hensen, Arjan; de Vries, Wim; Kros, Hans; van de Wal, Tamme; de Winter, Wim; Wien, Jan Erik; van Elswijk, Mark; Maat, Matthijs; Sanders, Kaj

    2002-03-01

    A nitrogen decision support system in the form of a game (NitroGenius) was developed for the Second International Nitrogen Conference. The aims were to: i) improve understanding among scientists and policy makers about the complexity of nitrogen pollution problems in an area of intensive agricultural, industrial, and transportation activity (The Netherlands); and ii) search for optimal policy solutions to prevent pollution effects at lowest economic and social costs. NitroGenius includes a model of nitrogen flows at relevant spatial and temporal scales including emissions of ammonia and nitrogen oxides and contamination of surface- and groundwaters. NitroGenius also includes an economic model describing relationships for important sectors and impacts of different nitrogen control measures on Gross Domestic Product (GDP), unemployment, energy use, and environmental costs. About 50 teams played NitroGenius during the Second International Nitrogen Conference. The results show that careful planning and selection of abatement options can solve Dutch nitrogen problems at reasonable cost.

  11. 基于政策前沿的最优货币供应机制研究%Optimal Money Supply Mechanism Based on Policy Frontiers

    Institute of Scientific and Technical Information of China (English)

    李霜; 简志宏

    2013-01-01

    构建了一个在货币政策中引入内生通货膨胀目标的动态随机一般均衡模型来研究最小化“产出-通货膨胀”波动的最优货币供应机制问题.贝叶斯参数估计表明,我国的货币供应机制具有较强的内生性;比较政策前沿发现,完全稳定和完全外生的通胀目标限制了货币政策的灵活性;而无平滑机制的动态通胀目标和有平滑机制的货币供应规则的政策组合能够满足货币当局在最优匹配产出波动和通胀波动时的相机抉择需要.%A dynamic stochastic general equilibrium model including an endogenous inflation target was constructed to analyze China's optimal money supply mechanism which could minimize the volatilities of output and inflation. Bayesian parameter estimation reveals the endogeneity of money supply mechanism. Meanwhile, both the completely stabilized inflation target and exogenous inflation targets reduce the flexibility of monetary policy. Among monetary policy mechanisms that optimally respond to economic condition, a combination of smoothing dynamic inflation target and non - smoothing money growth in monetary policy is a better policy choice according to the monetary frontier analysis.

  12. Optimal transfer, ordering and payment policies for joint supplier-buyer inventory model with price-sensitive trapezoidal demand and net credit

    Science.gov (United States)

    Shah, Nita H.; Shah, Digeshkumar B.; Patel, Dushyantkumar G.

    2015-07-01

    This study aims at formulating an integrated supplier-buyer inventory model when market demand is variable price-sensitive trapezoidal and the supplier offers a choice between discount in unit price and permissible delay period for settling the accounts due against the purchases made. This type of trade credit is termed as 'net credit'. In this policy, if the buyer pays within offered time M1, then the buyer is entitled for a cash discount; otherwise the full account must be settled by the time M2; where M2 > M1 ⩾ 0. The goal is to determine the optimal selling price, procurement quantity, number of transfers from the supplier to the buyer and payment time to maximise the joint profit per unit time. An algorithm is worked out to obtain the optimal solution. A numerical example is given to validate the proposed model. The managerial insights based on sensitivity analysis are deduced.

  13. Shoulder Joint Replacement

    Science.gov (United States)

    ... Shoulder Replacement Options Shoulder replacement surgery is highly technical. It should be performed by a surgical team ... area and will meet a doctor from the anesthesia department. You, your anesthesiologist, and your surgeon will ...

  14. Partial knee replacement - slideshow

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/presentations/100225.htm Partial knee replacement - series—Normal anatomy To use the sharing ... A.M. Editorial team. Related MedlinePlus Health Topics Knee Replacement A.D.A.M., Inc. is accredited ...

  15. Optimal operation policy for three types of batch distillation columns separating binary components; 2seibun bunri bacchi joryuto no saiteki kozo to saiteki sosa

    Energy Technology Data Exchange (ETDEWEB)

    Noda, M.; Hasebe, S.; Hashimoto, I. [Kyoto Univ. (Japan)

    1997-11-01

    The optimal reflux operation which minimizes energy consumption is derived for rectifying, stripping, and total reflux columns separating binary components. The batch distillation columns are modeled as differential and algebraic equation (DAE) systems. First, each DAE system is converted to a set of algebraic equations using orthogonal collocation on finite elements. Then, the problem of finding the optimal reflux policy is formulated as a nonlinear programming problem, and it is solved using successive quadratic programming techniques. The results of the example problems show that the separation performance of the total reflux column can be improved considerably by optimizing the reflux flow rate, though the separation performance of the rectifying column can not be improved so much, even if the reflux ratio is optimized. As a result, the energy consumption of the total reflux column is equal to or less than that of the rectifying column in most cases. The reason why the separation performance of the stripping column is worse than those of the other columns is made clear using the characteristics of vapor liquid equilibrium. 4 refs., 5 figs., 3 tabs.

  16. Study on Hubei Private Cultural Enterprises′Policy Optimization%湖北民营文化企业政策优化研究

    Institute of Scientific and Technical Information of China (English)

    夏露

    2013-01-01

    民营文化企业涉及非公有制的特别身份和文化特殊产业。基于这一特点,调查湖北民营文化企业政策现状,分析问题与成因,研究营造政策优化对策与实施建议,以给予湖北民营文化企业更多的支持、更好的政策实施条件,使之作为湖北经济发展新的增长点、转变文化产业发展方式的有效推动力。%Private cultural enterprises involve private special identity and cultural special industry, based on which the paper conducted a investigation into policy status quo of Hubei private cultur-al enterprises,analysed the problems and causes of the construction policy optimization counter-measures and proposals,with the hope of giving more support and better policy conditions to Hu-bei private cultural enterprises,as a new growth point of economic development,and the effec-tive impetus to transform the mode of cultural industry development in Hubei province.

  17. A Simulation Optimization Algorithm for CTMDPs Based on Randomized Stationary Policies%CTMDP基于随机平稳策略的仿真优化算法

    Institute of Scientific and Technical Information of China (English)

    唐昊; 奚宏生; 殷保群

    2004-01-01

    基于Markov性能势理论和神经元动态规划(NDP)方法,研究一类连续时间Markov决策过程(MDP)在随机平稳策略下的仿真优化问题,给出的算法是把一个连续时间过程转换成其一致化Markov链,然后通过其单个样本轨道来估计平均代价性能指标关于策略参数的梯度,以寻找次优策略,该方法适合于解决大状态空间系统的性能优化问题.并给出了一个受控Markov过程的数值实例.%Based on the theory of Markov performance potentials and neuro-dynamic programming (NDP) methodology, we study simulation optimization algorithm for a class of continuous time Markov decision processes (CTMDPs) under randomized stationary policies. The proposed algorithm will estimate the gradient of average cost performance measure with respect to policy parameters by transforming a continuous time Markov process into a uniform Markov chain and simulating a single sample path of the chain. The goal is to look for a suboptimal randomized stationary policy. The algorithm derived here can meet the needs of performance optimization of many difficult systems with large-scale state space. Finally, a numerical example for a controlled Markov process is provided.

  18. Strategic vehicle fleet management - the replacement problem

    Directory of Open Access Journals (Sweden)

    Adam Redmer

    2016-03-01

    Full Text Available Background: Fleets constitute the most important production means in transportation. Their appropriate management is crucial for all companies having transportation duties. The paper is the third one of a series of three papers that the author dedicates to the strategic vehicle fleet management topic. Material and methods: The paper discusses ways of building replacement strategies for companies' fleets of vehicles. It means deciding for how long to exploit particular vehicles in a fleet (the fleet replacement problem - FR. The essence of this problem lies in the minimization of vehicle / fleet exploitation costs by balancing ownership and utilization costs and taking into account budget limitations. In the paper an original mathematical model (an optimization method allowing for the FR analysis is proposed. Results: An application of the proposed optimization method in a real-life decision situation (the case study within the Polish environment and the obtained solution are presented. The solution shows that there exist optimal exploitation periods of particular vehicles in a fleet. However, combination of them gives a replacement plan for an entire fleet violating budget constraints. But it is possible to adjust individual age to replacement of particular vehicles to fulfill budget constraints without losing economical optimality of a developed replacement plan for an entire fleet. Conclusions: The paper is the last one of a series of three papers that the author dedicated to the strategic vehicle fleet management topic including the following managerial decision problems: MAKE-or-BUY, sizing / composition and replacement.

  19. Ensuring an optimal environment for peer education in South African schools: Goals, systems, standards and policy options for effective learning.

    Science.gov (United States)

    Swartz, Sharlene; Deutsch, Charles; Moolman, Benita; Arogundade, Emma; Isaacs, Dane; Michel, Barbara

    2016-12-01

    Peer education has long been seen as a key health promotion strategy and an important tool in preventing HIV infection. In South African schools, it is currently one of the strategies employed to do so. Based on both a recent research study of peer education across 35 schools and drawing on multiple previous studies in South Africa, this paper examines the key elements of peer education that contribute to its effectiveness and asks how this aligns with current educational and health policies. From this research, it summarises and proposes shared goals and aims, minimum standards of implementation and reflects on the necessary infrastructure required for peer education to be effective. In light of these findings, it offers policy recommendations regarding who should be doing peer education and the status peer education should have in a school's formal programme.

  20. сисOptimization of the state information policy of Ukraine in the conditions of contemporary modernization processes

    Directory of Open Access Journals (Sweden)

    E. O. Romanenko

    2014-10-01

    Today in Ukraine is a strategic document that at the national level to govern the main priorities, directions, principles, principles and ways of realization of the State policy on implementing its information and communication functions. Moreover the communicative component state is not clearly separated from the information, and therefore does not have the proper conceptual, technological and functional software, also destablzacjno affects the livelihoods of its public sector.

  1. Iron replacement therapy

    DEFF Research Database (Denmark)

    Nielsen, Ole Haagen; Coskun, Mehmet; Weiss, Günter

    2016-01-01

    PURPOSE OF REVIEW: Approximately, one-third of the world's population suffers from anemia, and at least half of these cases are because of iron deficiency. With the introduction of new intravenous iron preparations over the last decade, uncertainty has arisen when these compounds should be admini...... treatment, when to follow-up for relapse, which dosage and type of therapy should be recommended or not recommended, and if some patients should not be treated....... be administered and under which circumstances oral therapy is still an appropriate and effective treatment. RECENT FINDINGS: Numerous guidelines are available, but none go into detail about therapeutic start and end points or how iron-deficiency anemia should be best treated depending on the underlying cause...... of iron deficiency or in regard to concomitant underlying or additional diseases. SUMMARY: The study points to major issues to be considered in revisions of future guidelines for the true optimal iron replacement therapy, including how to assess the need for treatment, when to start and when to stop...

  2. A game theory-reinforcement learning (GT-RL) method to develop optimal operation policies for multi-operator reservoir systems

    Science.gov (United States)

    Madani, Kaveh; Hooshyar, Milad

    2014-11-01

    Reservoir systems with multiple operators can benefit from coordination of operation policies. To maximize the total benefit of these systems the literature has normally used the social planner's approach. Based on this approach operation decisions are optimized using a multi-objective optimization model with a compound system's objective. While the utility of the system can be increased this way, fair allocation of benefits among the operators remains challenging for the social planner who has to assign controversial weights to the system's beneficiaries and their objectives. Cooperative game theory provides an alternative framework for fair and efficient allocation of the incremental benefits of cooperation. To determine the fair and efficient utility shares of the beneficiaries, cooperative game theory solution methods consider the gains of each party in the status quo (non-cooperation) as well as what can be gained through the grand coalition (social planner's solution or full cooperation) and partial coalitions. Nevertheless, estimation of the benefits of different coalitions can be challenging in complex multi-beneficiary systems. Reinforcement learning can be used to address this challenge and determine the gains of the beneficiaries for different levels of cooperation, i.e., non-cooperation, partial cooperation, and full cooperation, providing the essential input for allocation based on cooperative game theory. This paper develops a game theory-reinforcement learning (GT-RL) method for determining the optimal operation policies in multi-operator multi-reservoir systems with respect to fairness and efficiency criteria. As the first step to underline the utility of the GT-RL method in solving complex multi-agent multi-reservoir problems without a need for developing compound objectives and weight assignment, the proposed method is applied to a hypothetical three-agent three-reservoir system.

  3. Electrocatalysts Prepared by Galvanic Replacement

    Directory of Open Access Journals (Sweden)

    Athanasios Papaderakis

    2017-03-01

    Full Text Available Galvanic replacement is the spontaneous replacement of surface layers of a metal, M, by a more noble metal, Mnoble, when the former is treated with a solution containing the latter in ionic form, according to the general replacement reaction: nM + mMnoblen+ → nMm+ + mMnoble. The reaction is driven by the difference in the equilibrium potential of the two metal/metal ion redox couples and, to avoid parasitic cathodic processes such as oxygen reduction and (in some cases hydrogen evolution too, both oxygen levels and the pH must be optimized. The resulting bimetallic material can in principle have a Mnoble-rich shell and M-rich core (denoted as Mnoble(M leading to a possible decrease in noble metal loading and the modification of its properties by the underlying metal M. This paper reviews a number of bimetallic or ternary electrocatalytic materials prepared by galvanic replacement for fuel cell, electrolysis and electrosynthesis reactions. These include oxygen reduction, methanol, formic acid and ethanol oxidation, hydrogen evolution and oxidation, oxygen evolution, borohydride oxidation, and halide reduction. Methods for depositing the precursor metal M on the support material (electrodeposition, electroless deposition, photodeposition as well as the various options for the support are also reviewed.

  4. Note: Optimal base-stock policy for the inventory system with periodic review, backorders and sequential lead times

    DEFF Research Database (Denmark)

    Johansen, Søren Glud; Thorstenson, Anders

    We show that well-known textbook formulae for determining the optimal base stock of the inventory system with continuous review and constant lead time can easily be extended to the case with periodic review and stochastic, sequential lead times. The provided performance measures and conditions...

  5. Optimal base-stock policy for the inventory system with periodic review, backorders and sequential lead times

    DEFF Research Database (Denmark)

    Johansen, Søren Glud; Thorstenson, Anders

    2008-01-01

    We extend well-known formulae for the optimal base stock of the inventory system with continuous review and constant lead time to the case with periodic review and stochastic, sequential lead times. Our extension uses the notion of the 'extended lead time'. The derived performance measures...

  6. Expected frontiers: Incorporating weather uncertainty into a policy analysis using an integrated bi-level multi-objective optimization framework

    Science.gov (United States)

    Weather is the main driver in both plant use of nutrients and fate and transport of nutrients in the environment. In previous work, we evaluated a green tax for control of agricultural nutrients in a bi-level optimization framework that linked deterministic models. In this study,...

  7. Optimal base-stock policy for the inventory system with periodic review, backorders and sequantial lead times

    DEFF Research Database (Denmark)

    Johansen, Søren Glud; Thorstenson, Anders

    2008-01-01

    We extend well-known formulae for the optimal base stock of the inventory system with continuous review and constant lead time to the case with periodic review and stochastic, sequential lead times. Our extension uses the notion of the ‘extended lead time’. The derived performance measures...

  8. Advance demand information and a restricted production capacity : On the optimality of order base-stock policies

    NARCIS (Netherlands)

    Wijngaard, Jacob; Karaesmen, Fikri

    2007-01-01

    This paper considers the optimality of order aggregation in a single-item production/inventory problem with advance demand information and a restricted production capacity. The advance demand information is modeled by introducing a positive customer order lead time. The paper proves, when customer o

  9. Optimal base-stock policy for the inventory system with periodic review, backorders and sequantial lead times

    DEFF Research Database (Denmark)

    Johansen, Søren Glud; Thorstenson, Anders

    2008-01-01

    We extend well-known formulae for the optimal base stock of the inventory system with continuous review and constant lead time to the case with periodic review and stochastic, sequential lead times. Our extension uses the notion of the ‘extended lead time’. The derived performance measures...

  10. Simple heuristics for push and pull remanufacturing policies

    NARCIS (Netherlands)

    E.A. van der Laan (Erwin); R.H. Teunter (Ruud)

    2004-01-01

    textabstractInventory policies for joint remanufacturing and manufacturing have recently received much attention. Most efforts, though, were related to (optimal) policy structures and numerical optimization, rather than closed form expressions for calculating near optimal policy parameters. The

  11. Deadlock Prevention Policy with Behavioral Optimality or Suboptimality Achieved by the Redundancy Identification of Constraints and the Rearrangement of Monitors

    Directory of Open Access Journals (Sweden)

    Liang Hong

    2015-01-01

    Full Text Available This work develops an iterative deadlock prevention method for a special class of Petri nets that can well model a variety of flexible manufacturing systems. A deadlock detection technique, called mixed integer programming (MIP, is used to find a strict minimal siphon (SMS in a plant model without a complete enumeration of siphons. The policy consists of two phases. At the first phase, SMSs are obtained by MIP technique iteratively and monitors are added to the complementary sets of the SMSs. For the possible existence of new siphons generated after the first phase, we add monitors with their output arcs first pointed to source transitions at the second phase to avoid new siphons generating and then rearrange the output arcs step by step on condition that liveness is preserved. In addition, an algorithm is proposed to remove the redundant constraints of the MIP problem in this paper. The policy improves the behavioral permissiveness of the resulting net and greatly enhances the structural simplicity of the supervisor. Theoretical analysis and experimental results verify the effectiveness of the proposed method.

  12. Optimal Ordering Policy and Coordination Mechanism of a Supply Chain with Controllable Lead-Time-Dependent Demand Forecast

    Directory of Open Access Journals (Sweden)

    Hua-Ming Song

    2011-01-01

    Full Text Available This paper investigates the ordering decisions and coordination mechanism for a distributed short-life-cycle supply chain. The objective is to maximize the whole supply chain's expected profit and meanwhile make the supply chain participants achieve a Pareto improvement. We treat lead time as a controllable variable, thus the demand forecast is dependent on lead time: the shorter lead time, the better forecast. Moreover, optimal decision-making models for lead time and order quantity are formulated and compared in the decentralized and centralized cases. Besides, a three-parameter contract is proposed to coordinate the supply chain and alleviate the double margin in the decentralized scenario. In addition, based on the analysis of the models, we develop an algorithmic procedure to find the optimal ordering decisions. Finally, a numerical example is also presented to illustrate the results.

  13. Wireless Powered Relaying Networks Under Imperfect Channel State Information: System Performance and Optimal Policy for Instantaneous Rate

    Directory of Open Access Journals (Sweden)

    D. T. Do

    2017-09-01

    Full Text Available In this investigation, we consider wireless powered relaying systems, where energy is scavenged by a relay via radio frequency (RF signals. We explore hybrid time switching-based and power splitting-based relaying protocol (HTPSR and compare performance of Amplify-and-Forward (AF with Decode-and-Forward (DF scheme under imperfect channel state information (CSI. Most importantly, the instantaneous rate, achievable bit error rate (BER are determined in the closed-form expressions under the impact of imperfect CSI. Through numerical analysis, we evaluate system insights via different parameters such as power splitting (PS and time switching (TS ratio of the considered HTPSR which affect outage performance and BER. It is noted that DF relaying networks outperform AF relaying networks. Besides that, the numerical results are given to prove the optimization problems of PS and TS ratio to obtain optimal instantaneous rate.

  14. Aeronautical Information System Replacement -

    Data.gov (United States)

    Department of Transportation — Aeronautical Information System Replacement is a web-enabled, automation means for the collection and distribution of Service B messages, weather information, flight...

  15. An optimal deterministic control policy of servers in front and back rooms with a variable number of switching points and switching costs

    Institute of Scientific and Technical Information of China (English)

    WANG JiaMin

    2009-01-01

    In this paper we consider a retail service facility with cross-trained workers who can perform operations in both the front room and back room. Workers are brought from the back room to the front room and vice versa depending on the number of customers in the system. A loss of productivity occurs when a worker returns to the back room. Two problems are studied. In the first problem, given the number of workers available, we determine an optimal deterministic switching policy so that the expected number of customers in queue is minimized subject to a constraint ensuring that there is a sufficient workforce to fulfill the functions in the back room. In the second problem, the number of workers needed is minimized subject to an additional constraint requiring that the expected number of customers waiting in queue is bounded above by a given threshold value. Exact solution procedures are developed and illustrative numerical examples are presented.

  16. Knee Replacement for Women with Patient-Specific Instructions

    Medline Plus

    Full Text Available Knee Replacement for Women with Patient-Specific Instructions Click Here to view the BroadcastMed, Inc. Privacy Policy and Legal Notice © 2017 BroadcastMed, Inc. All rights reserved.

  17. Knee Replacement for Women with Patient-Specific Instructions

    Medline Plus

    Full Text Available Knee Replacement for Women with Patient-Specific Instructions Click Here to view the BroadcastMed, Inc. Privacy Policy and Legal Notice © 2017 BroadcastMed, Inc. All rights reserved.

  18. 基于非对称通胀偏好的最优货币政策规则%Optimal Monetary Policy Rules under Asymmetric inflation preferences

    Institute of Scientific and Technical Information of China (English)

    黄皂右

    2011-01-01

    与传统的L—Q货币政策分析框架相异,本文通过Linex函数,在央行损失函数中引入非对称通胀目标偏好。新的货币政策动态优化模型分析结果表明,最优货币政策规则中,名义利率对通胀的反应是非线性的,利率工具不仅对通胀水平作出反应,而且对通胀的波动·陛也作出反应,利率对通胀的变化还产生符号与大小上的非对称。%This paper derives optimal monetary policy rules in setups where central bank's inflation preferences are non-symmetry and macroeconomic constraints is linear. Analytical results show that the inclusion of asymmetric inflation preferences leads to sign and size asymmetries, and non-linearities in the respondence of interest rate to inflation change in the new monetary policy rule.

  19. Government Preference and the Optimal Choice of R&D Subsidy Policy: Innovation Subsidy or Product Subsidy?

    Directory of Open Access Journals (Sweden)

    Yongcong Yang

    2014-01-01

    Full Text Available Taking government preference into consideration, we consider a three-stage game model to compare the differences of innovation subsidy and product subsidy. The findings reveal that stronger preference to consumers’ welfare leads to higher subsidy rates, which benefit not only consumers but also firms. To choose between the two subsidies, the optimal choice varies with the changing preference of policymakers. According to the results of numerical simulation, product subsidy is better than innovation subsidy in most cases, while the government’s expenditure of the former one is larger than the latter one. Moreover, subsidizing firms symmetrically and asymmetrically has different effects on the consequences.

  20. 递归效用、生产性政府支出与最优财政政策%RECURSIVE UTILITY,PRODUCTIVE GOVERNMENT EXPENDITURE AND OPTIMAL FISCAL POLICY

    Institute of Scientific and Technical Information of China (English)

    王海军; 胡适耕; 张学清

    2005-01-01

    This paper employs a stochastic endogenous growth model extended to the case of a recursive utility function which can disentangle intertemporal substitution from risk aversion to analyze productive government expenditure and optimal fiscal policy,particularly stresses the importance of factor income. First,the explicit solutions of the central planner's stochastic optimization problem are derived,the growth-maximizing and welfare-maximizing government expenditure policies are obtained and their standing in conflict or coincidence depends upon intertemporal substitution. Second,the explicit solutions of the representative individual's stochastic optimization problem which permits to tax on capital income and labor income separately are derived,and it is found that the effect of risk on growth crucially depends on the degree of risk aversion,the intertemporal elasticity of substitution and the capital income share. Finally, a flexible optimal tax policy which can be internally adjusted to a certain extent is derived,and it is found that the distribution of factor income plays an important role in designing the optimal tax policy.

  1. Radiation Source Replacement Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, Jeffrey W.; Moran, Traci L.; Bond, Leonard J.

    2010-12-01

    This report summarizes a Radiation Source Replacement Workshop in Houston Texas on October 27-28, 2010, which provided a forum for industry and researchers to exchange information and to discuss the issues relating to replacement of AmBe, and potentially other isotope sources used in well logging.

  2. A multi-objective model for closed-loop supply chain optimization and efficient supplier selection in a competitive environment considering quantity discount policy

    Science.gov (United States)

    Jahangoshai Rezaee, Mustafa; Yousefi, Samuel; Hayati, Jamileh

    2016-11-01

    Supplier selection and allocation of optimal order quantity are two of the most important processes in closed-loop supply chain (CLSC) and reverse logistic (RL). So that providing high quality raw material is considered as a basic requirement for a manufacturer to produce popular products, as well as achieve more market shares. On the other hand, considering the existence of competitive environment, suppliers have to offer customers incentives like discounts and enhance the quality of their products in a competition with other manufacturers. Therefore, in this study, a model is presented for CLSC optimization, efficient supplier selection, as well as orders allocation considering quantity discount policy. It is modeled using multi-objective programming based on the integrated simultaneous data envelopment analysis-Nash bargaining game. In this study, maximizing profit and efficiency and minimizing defective and functions of delivery delay rate are taken into accounts. Beside supplier selection, the suggested model selects refurbishing sites, as well as determining the number of products and parts in each network's sector. The suggested model's solution is carried out using global criteria method. Furthermore, based on related studies, a numerical example is examined to validate it.

  3. The optimal age of measles immunisation in low-income countries: a secondary analysis of the assumptions underlying the current policy

    Science.gov (United States)

    Martins, Cesário L; Garly, May-Lill; Rodrigues, Amabelia; Benn, Christine S; Whittle, Hilton

    2012-01-01

    vaccine failures’ lead to lack of confidence found the opposite because vaccinated children had milder measles infection. Fifth, a one-dose policy was recommended. However, the two randomised trials of early two-dose measles vaccination compared with one-dose vaccination found significantly reduced mortality until 3 years of age. Thus, current evidence suggests that the optimal age for a single dose of measles vaccine should have been 6 or 7 months resulting in fewer severe unvaccinated cases among infants but more mild ‘vaccine failures’ among older children. Furthermore, the two-dose trials indicate that measles vaccine reduces mortality from other causes than measles infection. Conclusions Many lives may have been lost by not determining the optimal age of measles vaccination. Since seroconversion continues to be the basis for policy, the current recommendation is to increase the age of measles vaccination to 12 months in countries with limited measles transmission. This policy may lead to an increase in child mortality. PMID:22815465

  4. 失业波动、社会福利损失与中国最优货币政策%Unemployment Fluctuation, Welfare Loss and the Optimal Monetary Policy in China

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    This paper considers the optimal policy in China through constructing and calibrating a new Keynesian monetary policy dynamic general equilibrium model with unemployment and physical capital .And we find that the optimal policy lead to the least social welfare loss .Based on this, we investigate the optimal discretionary, commitment and the optimal simple rule and the social welfare loss caused by these policies . The results show that the optimal simple rule targeting inflation and wage inflation mostly approximates the op -timal policy rule.This conclusion has important policy implications for China′s economy.%  通过构建并校准一个包含失业与物质资本的新凯恩斯主义货币政策动态随机一般均衡框架,笔者考察了存在失业情形的中国最优货币政策问题。笔者分别考察与比较了最优相机抉择货币政策、完全承诺以及严格盯住通货膨胀、严格盯住工资通胀、混合规则等最优简单货币政策规则下的社会福利损失,结果表明混合规则的最优简单货币政策规则所带来的社会福利损失与最优货币政策规则最为接近。这一结论对于失业问题日益严峻背景下我国货币政策盯住目标的选取具有重要的现实意义。

  5. Replacing a Missing Tooth

    Science.gov (United States)

    ... vessels in the tooth pulps are rather large. Drilling down these teeth for crowns may expose the ... porcelain replacement tooth is held in place by metal extensions cemented to the backs of the adjacent ...

  6. Hormone Replacement Therapy

    Science.gov (United States)

    ... before and during menopause, the levels of female hormones can go up and down. This can cause ... hot flashes and vaginal dryness. Some women take hormone replacement therapy (HRT), also called menopausal hormone therapy, ...

  7. Knee joint replacement

    Science.gov (United States)

    ... of your kneecap. Your kneecap is called the patella. The replacement part is usually made from a ... long. Then your surgeon will: Move your kneecap (patella) out of the way, then cut the ends ...

  8. Knee joint replacement - slideshow

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/presentations/100088.htm Knee joint replacement - series—Normal anatomy To use the ... to slide 4 out of 4 Overview The knee is a complex joint. It contains the distal ...

  9. Product Platform Replacements

    DEFF Research Database (Denmark)

    Sköld, Martin; Karlsson, Christer

    2012-01-01

    Purpose – It is argued in this article that too little is known about product platforms and how to deal with them from a manager's point of view. Specifically, little information exists regarding when old established platforms are replaced by new generations in R&D and production environments...... originality and value is achieved by focusing on product platform replacements believed to represent a growing management challenge....

  10. Renal replacement therapy for acute renal failure.

    Science.gov (United States)

    Macedo, E; Bouchard, J; Mehta, R L

    2009-09-01

    Renal replacement therapy became a common clinical tool to treat patients with severe acute kidney injury (AKI) since the 1960s. During this time dialytic options have expanded considerably; biocompatible membranes, bicarbonate dialysate and dialysis machines with volumetric ultrafiltration control have improved the treatment for acute kidney injury. Along with advances in methods of intermittent hemodialysis, continuous renal replacement therapies have gained widespread acceptance in the treatment of dialysis-requiring AKI. However, many of the fundamental aspects of the renal replacement treatment such as indication, timing of dialytic intervention, and choice of dialysis modality are still controversial and may influence AKI patient's outcomes. This review outlines current concepts in the use of dialysis techniques for AKI and suggests an approach for selecting the optimal method of renal replacement therapy.

  11. Maternal death inquiry and response in India - the impact of contextual factors on defining an optimal model to help meet critical maternal health policy objectives

    Directory of Open Access Journals (Sweden)

    Kalter Henry D

    2011-11-01

    Full Text Available Abstract Background Maternal death reviews have been utilized in several countries as a means of identifying social and health care quality issues affecting maternal survival. From 2005 to 2009, a standardized community-based maternal death inquiry and response initiative was implemented in eight Indian states with the aim of addressing critical maternal health policy objectives. However, state-specific contextual factors strongly influenced the effort's success. This paper examines the impact and implications of the contextual factors. Methods We identified community, public health systems and governance related contextual factors thought to affect the implementation, utilization and up-scaling of the death inquiry process. Then, according to selected indicators, we documented the contextual factors' presence and their impact on the process' success in helping meet critical maternal health policy objectives in four districts of Rajasthan, Madhya Pradesh and West Bengal. Based on this assessment, we propose an optimal model for conducting community-based maternal death inquiries in India and similar settings. Results The death inquiry process led to increases in maternal death notification and investigation whether civil society or government took charge of these tasks, stimulated sharing of the findings in multiple settings and contributed to the development of numerous evidence-based local, district and statewide maternal health interventions. NGO inputs were essential where communities, public health systems and governance were weak and boosted effectiveness in stronger settings. Public health systems participation was enabled by responsive and accountable governance. Communities participated most successfully through India's established local governance Panchayat Raj Institutions. In one instance this led to the development of a multi-faceted intervention well-integrated at multiple levels. Conclusions The impact of several contextual

  12. 基于监管的保险公司最优比例再保险策略%OPTIMAL PROPORTIONAL REINSURANCE POLICY BASED ON REGULATIONS

    Institute of Scientific and Technical Information of China (English)

    曾燕; 李仲飞

    2009-01-01

    According to regulations, an insurance company must convert a certain level of reserve. In view of this, the insurer must keep its surplus no less than this reserve level. In this paper, the "ruin" time is denned as the first time to achieve the reserve level, and the target is to minimize the "ruin" probability of the insurer. It is assumed that the surplus process is described by a diffusion model, the insurer can purchase proportional reinsurance and its surplus is appreciated according to continuous compound interest with a constant force of interest. By using the stochastic dynamic programming approach, explicit expressions of the optimal value function and the optimal proportional reinsurance policy are obtained via solving the corresponding HJB equation. Finally, some economical explanations and a numerical example are provided.%根据监管规定,保险公司必须提存一定水平的准备金.鉴于此,保险公司必须保持盈余不低于这个准备金水平.将保险公司盈余首达该准备金水平的时刻定义为"破产"时刻,以最小化"破产"概率为目标;假设保险公司可购买比例再保险,其盈余过程由扩散模型刻画且盈余按连续复利方式计算利息,其中利力为常数;借助随机动态规划方法,通过求解相应的HJB方程得到了最优值函数与最优比例再保险策略的解析式.最后给出了经济解释与数值算例.

  13. Exploration of an Optimal Policy for Water Resources Management Including the Introduction of Advanced Sewage Treatment Technologies in Zaozhuang City, China

    Directory of Open Access Journals (Sweden)

    Gengyu He

    2016-12-01

    Full Text Available Water shortage and water pollution are important factors restricting sustainable social and economic development. As a typical coal resource-exhausted city and a node city of the South-to-North Water Transfer East Route Project in China, Zaozhuang City’s water resources management faces multiple constraints such as transformation of economic development, restriction of groundwater exploitation, and improvement of water environment. In this paper, we develop a linear optimization model by input–output analysis to study water resources management with the introduction of three advanced sewage treatment technologies for pollutant treatment and reclaimed water production. The simulation results showed that from 2014 to 2020, Zaozhuang City will realize an annual GDP growth rate of 7.1% with an annual chemical oxygen demand (COD emissions reduction rate of 5.5%. The proportion of primary industry, secondary industry, and tertiary industry would be adjusted to 5.6%, 40.8%, and 53.6%, respectively. The amount of reclaimed water supply could be increased by 91% and groundwater supply could be decreased by 6%. Based on the simulation, this model proposes a scientific reference on water resources management policies, including water environment control, water supply plan, and financial subsidy, to realize the sustainable development of economy and water resources usage.

  14. Predictive maintenance policy for a gradually deteriorating system subject to stress

    Energy Technology Data Exchange (ETDEWEB)

    Deloux, E. [IRCCyN/Ecole des Mines de Nantes, Nantes (France); Castanier, B. [IRCCyN/Ecole des Mines de Nantes, Nantes (France)], E-mail: bruno.castanier@emn.fr; Berenguer, C. [Universite de Technologie de Troyes/CNRS, Troyes (France)

    2009-02-15

    This paper deals with a predictive maintenance policy for a continuously deteriorating system subject to stress. We consider a system with two failure mechanisms which are, respectively, due to an excessive deterioration level and a shock. To optimize the maintenance policy of the system, an approach combining statistical process control (SPC) and condition-based maintenance (CBM) is proposed. CBM policy is used to inspect and replace the system according to the observed deterioration level. SPC is used to monitor the stress covariate. In order to assess the performance of the proposed maintenance policy and to minimize the long-run expected maintenance cost per unit of time, a mathematical model for the maintained system cost is derived. Analysis based on numerical results are conducted to highlight the properties of the proposed maintenance policy in respect to the different maintenance parameters.

  15. Central bank learning and monetary policy

    OpenAIRE

    Tesfaselassie, Mewael F.

    2008-01-01

    We analyze optimal monetary policy when a central bank has to learn about an unknown coefficient that determines the effect of surprise inflation on aggregate demand. We derive the optimal policy under active learning and compare it to two limiting cases---certainty equivalence policy and cautionary policy, in which learning takes place passively. Our novel result is that the two passive learning policies represent an upper and lower bound for the active learning policy, irrespective of the s...

  16. Central bank learning and monetary policy

    OpenAIRE

    Tesfaselassie, Mewael F.

    2008-01-01

    We analyze optimal monetary policy when a central bank has to learn about an unknown coefficient that determines the effect of surprise inflation on aggregate demand. We derive the optimal policy under active learning and compare it to two limiting cases---certainty equivalence policy and cautionary policy, in which learning takes place passively. Our novel result is that the two passive learning policies represent an upper and lower bound for the active learning policy, irrespective of the s...

  17. Performance and economic effects of partially replacing soybean ...

    African Journals Online (AJOL)

    Performance and economic effects of partially replacing soybean meal with palm kernel ... to determine the optimal level of inclusion for maximum production in broilers. ... while no PKC was used in treatment I, which also served as the control.

  18. Optimal implantation depth and adherence to guidelines on permanent pacing to improve the results of transcatheter aortic valve replacement with the medtronic corevalve system: The CoreValve prospective, international, post-market ADVANCE-II study

    NARCIS (Netherlands)

    A.S. Petronio (Anna S.); J.-M. Sinning (Jan-Malte); N.M. van Mieghem (Nicolas); G. Zucchelli (Giulio); G. Nickenig (Georg); R. Bekeredjian (Raffi); B. Bosmans; F. Bedogni (Francesco); M. Branny (Marian); K. Stangl (Karl); J. Kovac (Jan); M. Schiltgen (Molly); S. Kraus (Stacia); P.P.T. de Jaegere (Peter)

    2015-01-01

    textabstractObjectives The aim of the CoreValve prospective, international, post-market ADVANCE-II study was to define the rates of conduction disturbances and permanent pacemaker implantation (PPI) after transcatheter aortic valve replacement with the Medtronic CoreValve System (Minneapolis, Minnes

  19. Optimal implantation depth and adherence to guidelines on permanent pacing to improve the results of transcatheter aortic valve replacement with the medtronic corevalve system: The CoreValve prospective, international, post-market ADVANCE-II study

    NARCIS (Netherlands)

    A.S. Petronio (Anna S.); J.-M. Sinning (Jan-Malte); N.M. van Mieghem (Nicolas); G. Zucchelli (Giulio); G. Nickenig (Georg); R. Bekeredjian (Raffi); B. Bosmans; F. Bedogni (Francesco); M. Branny (Marian); K. Stangl (Karl); J. Kovac (Jan); M. Schiltgen (Molly); S. Kraus (Stacia); P.P.T. de Jaegere (Peter)

    2015-01-01

    textabstractObjectives The aim of the CoreValve prospective, international, post-market ADVANCE-II study was to define the rates of conduction disturbances and permanent pacemaker implantation (PPI) after transcatheter aortic valve replacement with the Medtronic CoreValve System (Minneapolis, Minnes

  20. Robotic mitral valve replacement.

    Science.gov (United States)

    Senay, Sahin; Gullu, Ahmet Umit; Kocyigit, Muharrem; Degirmencioglu, Aleks; Karabulut, Hasan; Alhan, Cem

    2014-01-01

    Robotic surgical techniques allow surgeons to perform mitral valve surgery. This procedure has gained acceptance, particularly for mitral valve repair in degenerative mitral disease. However, mitral repair may not always be possible, especially in severely calcified mitral valve of rheumatic origin. This study demonstrates the basic concepts and technique of robotic mitral valve replacement for valve pathologies that are not suitable for repair.

  1. Replacing America's Job Bank

    Science.gov (United States)

    Vollman, Jim

    2009-01-01

    The Job Central National Labor Exchange (www.jobcentral.com) has become the effective replacement for America's Job Bank with state workforce agencies and, increasingly, with community colleges throughout the country. The American Association of Community Colleges (AACC) has formed a partnership with Job Central to promote its use throughout the…

  2. Replacing America's Job Bank

    Science.gov (United States)

    Vollman, Jim

    2009-01-01

    The Job Central National Labor Exchange (www.jobcentral.com) has become the effective replacement for America's Job Bank with state workforce agencies and, increasingly, with community colleges throughout the country. The American Association of Community Colleges (AACC) has formed a partnership with Job Central to promote its use throughout the…

  3. Firm′s Optimal Production Decision with Exogenous Abatement Policy%外生减排政策约束下企业最优生产决策分析

    Institute of Scientific and Technical Information of China (English)

    涂强; 李炳丽

    2015-01-01

    通过构建企业利润最大化的动态最优控制模型,分析了企业分别在单一碳限额政策、单一碳税政策,以及由碳税和碳限额组成的混合政策下的生产决策问题。研究表明,相对于单一碳限额政策,混合政策能更早实现目标碳限额量;而相对于单一碳税政策,混合政策下的CO2排放量更小。企业产量在单一碳税政策下随碳税率的递增而递减,而在混合政策下存在碳税率阈值,政府制定的碳税率大于(小于)该阈值时,企业产量随碳税率的增加而增加(减少);最后通过数值模拟验证了所得结论的有效性。%An optimal control model was established to maximize the firm′s profits.The firm′s optimal production decision was analyzed under three different exogenous abatement policies:the carbon tax policy , the carbon constraints policy , and the hy-brid policy of carbon tax and carbon constraints .The results indicate that the firm′s CO2 emissions under the hybrid policy reach the carbon constraints earlier than that under the carbon constraints policy , and CO2 emissions under the hybrid policy are less than that under the carbon tax policy .In addition, the firm′s outputs are declining with the increase of carbon tax rate under the carbon tax policy .However , under the hybrid policy , there exists a threshold .When the carbon tax rate designed by the govern-ment is more (less) than this threshold, the firm′s output are increasing (decreasing) with the increase of carbon tax rate.Fi-nally, one numerical example was given to illustrate the effectiveness of these proposed models .

  4. Optimal Policy in OG Models

    DEFF Research Database (Denmark)

    Ghiglino, Christian; Tvede, Mich

    2000-01-01

    In the present paper general stationary overlapping generations economies with many commodities in every period and many different consumers in every generation are considered. A government maximizes a utilitarian social welfare function, which is the sum of weighted averages of utilities...

  5. 中国能源战略调整和能源政策优化研究%Research on China's Energy Strategies Adjustment and Energy Policy Optimization

    Institute of Scientific and Technical Information of China (English)

    林伯强

    2012-01-01

    针对中国现阶段城市化、工业化加速发展阶段能源需求刚性特征以及能源稀缺(能源价格走高)和环境问题(应对气候变化)日益凸显,提出中国需要通过调整能源战略(改变以前简单地从能源供给侧考虑满足能源需求,将节能作为满足能源需求的一个组成部分;改变仅受资源约束的能源供需增长和能源结构战略规划,将CO2排放作为满足能源需求的约束;改变仅从能源供给侧考虑能源安全;各能源行业的战略规划必须站到整体能源的高度,改变以往各行业单独进行战略规划.)和优化政策选择(依据实际制定节能减排目标;正确把握能源需求这一有效能源战略规划的起点;重视中国低碳经济发展成本问题;兼顾能源强度和碳强度目标),以实现现阶段经济发展可以接受的能源结构和能源成本目标.%In response to the indispensibility of energy demand on the current stage of accelerated urbanization and industrialization in China, the scarcity of energy (demonstrated by surging energy price), and the growing environment problem (how to address climate change), this paper proposes that China should adjust its energy strategies and optimize policy selection to realize the goals of energy structure and energy cost acceptable to the current economical development. The adjustment of energy strategies includes adopting the energy saving as a means to meet the energy demand, taking the CO2 emission as a binding factor, ensuring energy security from both supply and demand sides, comprehensive planning of the energy sector (rather than isolated planning of single energy sector), and optimization of policy selection (making the emission reduction goal based on the real conditions, properly handling the starting point of the effective planning of energy strategies; sufficient attention to the cost of the low carbon industry in China and balanced consideration of the energy intensity

  6. Survey of maintenance policies for the Last 50 Years

    Directory of Open Access Journals (Sweden)

    Asis Sarkar

    2011-08-01

    Full Text Available In the past several decades, maintenance and replacement problems have been extensively studied inthe literature. Thousands of maintenance and replacement models have been created. However, all thesemodels can fall into some categories of maintenance policies: age replacement policy, block replacementpolicy, periodic preventive maintenance policy, failure limit policy, sequential preventive maintenancepolicy, repair cost limit policy, repair time limit policy, repair number counting policy, reference timepolicy, mixed age policy, group maintenance policy, opportunistic maintenance policy, etc. Each kind ofpolicy has different characteristics, advantages and disadvantages with lot of contributions fromResearch scientist, Technologists... This survey summarizes, classifies, and compares various existingmaintenance policies Around 170 Authors and their research works are presented in the Referencesection. It will help to look into the different policies which is appropriate to the organization and forfurther study the reference section will be helpful for the researchers for further knowledge

  7. Cultural Policy in Iceland

    DEFF Research Database (Denmark)

    Gudmundsson, Gestur

    2003-01-01

    The article examines the history of cultural policy in Iceland from a Nordic comparative perspective. National cultural policy takes form in the 19th and early 20th century as a part of the nation-building, emphasising the Icelandic language as the core of national identity, building cultural...... on the continuing emphasis on central cultural institution and the Icelandic language. Since the 1970s Cold War conflicts have been replaced by a consensus on growing support to artists and an armth's length policy, and furthermore the 1990s have seen a strong move towards NPM and international participation....

  8. China currency policy tool's optimization in late finance crisis time%后金融危机时代我国货币政策工具的优化

    Institute of Scientific and Technical Information of China (English)

    胡晔

    2012-01-01

    货币政策是我国宏观经济调控的重要途径之一,在特定时期内制定实施合适的货币政策能够促进经济发展目标的实现。在以转变经济发展方式、优化经济结构为目标的后金融危机时代,货币政策的制定不仅要考虑对经济总量的调控,更要兼顾经济结构的调控。本文旨在对当前我国央行货币政策工具的实施情况进行归纳,以期发现新时期在兼顾总量与结构调控的背景下当前货币政策工具的不足,并提出优化货币政策工具的建议。%The monetary policy is one of the most important ways in China's macroeconomic regulation.Making appropriate monetary policy in the specific time would promote the realization of the economic development targets.In the transformation of the mode of economic development and optimizing economic structure as the goal in the new period,the formulation of monetary policy should be given not only to meet the total amount of economic regulation,but also to adjust the economic structure.This paper would summarize the current condition of the central bank's monetary policy tools,in order to find the shortcoming of the current monetary policy tools under the background of the new period in balancing with the gross adjusting and the control structure,in the same way to propose the suggestion of optimization monetary policy tools.

  9. Ulnar head replacement.

    Science.gov (United States)

    Herbert, Timothy J; van Schoonhoven, Joerg

    2007-03-01

    Recent years have seen an increasing awareness of the anatomical and biomechanical significance of the distal radioulnar joint (DRUJ). With this has come a more critical approach to surgical management of DRUJ disorders and a realization that all forms of "excision arthroplasty" can only restore forearm rotation at the expense of forearm stability. This, in turn, has led to renewed interest in prosthetic replacement of the ulnar head, a procedure that had previously fallen into disrepute because of material failures with early implants, in particular, the Swanson silicone ulnar head replacement. In response to these early failures, a new prosthesis was developed in the early 1990s, using materials designed to withstand the loads across the DRUJ associated with normal functional use of the upper limb. Released onto the market in 1995 (Herbert ulnar head prosthesis), clinical experience during the last 10 years has shown that this prosthesis is able to restore forearm function after ulnar head excision and that the materials (ceramic head and noncemented titanium stem), even with normal use of the limb, are showing no signs of failure in the medium to long term. As experience with the use of an ulnar head prosthesis grows, so does its acceptance as a viable and attractive alternative to more traditional operations, such as the Darrach and Sauve-Kapandji procedures. This article discusses the current indications and contraindications for ulnar head replacement and details the surgical procedure, rehabilitation, and likely outcomes.

  10. Random maintenance policies

    CERN Document Server

    Nakagawa, Toshio

    2014-01-01

    Exploring random maintenance models, this book provides an introduction to the implementation of random maintenance, and it is one of the first books to be written on this subject.  It aims to help readers learn new techniques for applying random policies to actual reliability models, and it provides new theoretical analyses of various models including classical replacement, preventive maintenance and inspection policies. These policies are applied to scheduling problems, backup policies of database systems, maintenance policies of cumulative damage models, and reliability of random redundant systems. Reliability theory is a major concern for engineers and managers, and in light of Japan’s recent earthquake, the reliability of large-scale systems has increased in importance. This also highlights the need for a new notion of maintenance and reliability theory, and how this can practically be applied to systems. Providing an essential guide for engineers and managers specializing in reliability maintenance a...

  11. 基于ERP的(s,S)策略下库存优化控制决策支持系统%INVENTORY CONTROL STRATEGY OPTIMIZATION DECISION SUPPORT SYSTEM BASED ON (s, S) POLICY IN ERP

    Institute of Scientific and Technical Information of China (English)

    李建斌; 罗晓萌; 吴建华; 温渤

    2011-01-01

    Because the ERP software can not dynamically obtain optimal order policy and false to effectively analyze historical data, this paper establishes optimization mathematical model under discount criteria in order to minimize inventory cost. We also analyze the data in ERP software and dynamically obtain all kinds of product's optimal order policy which are similar to (s, S) strategy. Furthermore, we design and develop inventory control strategy optimization decision support system which provides decision support for users and greatly reduce inventory cost for enterprise.%针对当前ERP软件系统无法动态地给出优化订购策略并对历史数据进行有效的分析等不足,以最小化库存费用为目标建立起折扣准则下库存优化数学模型,对ERP软件中导出的各类历史数据进行模型化分析,动态地得出各类产品(s,S)结构形式的优化订购策略.基于该模型设计并开发了库存优化控制决策支持系统,为用户提供决策支持,很大程度降低了企业库存费用.

  12. Aortic valve replacement

    DEFF Research Database (Denmark)

    Kapetanakis, Emmanouil I; Athanasiou, Thanos; Mestres, Carlos A

    2008-01-01

    BACKGROUND AND AIMS OF THE STUDY: Prompted by anecdotal evidence and observations by surgeons, an investigation was undertaken into the potential differences in implanted aortic valve prosthesis sizes, during aortic valve replacement (AVR) procedures, between northern and southern European...... countries. METHODS: A multi-institutional, non-randomized, retrospective analysis was conducted among 2,932 patients who underwent AVR surgery at seven tertiary cardiac surgery centers throughout Europe. Demographic and perioperative variables including valve size and type, body surface area (BSA) and early...

  13. Total ankle joint replacement.

    Science.gov (United States)

    2016-02-01

    Ankle arthritis results in a stiff and painful ankle and can be a major cause of disability. For people with end-stage ankle arthritis, arthrodesis (ankle fusion) is effective at reducing pain in the shorter term, but results in a fixed joint, and over time the loss of mobility places stress on other joints in the foot that may lead to arthritis, pain and dysfunction. Another option is to perform a total ankle joint replacement, with the aim of giving the patient a mobile and pain-free ankle. In this article we review the efficacy of this procedure, including how it compares to ankle arthrodesis, and consider the indications and complications.

  14. Patching vs Packaging in Policy Formulation: Assessing Policy Portfolio Design

    Directory of Open Access Journals (Sweden)

    Michael Howlett

    2013-10-01

    Full Text Available Thinking about policy mixes is at the forefront of current research work in the policy sciences and raises many significant questions with respect to policy tools and instruments, processes of policy formulation, and the evolution of tool choices over time. Not least among these is how to assess the potential for multiple policy tools to achieve policy goals in an efficient and effective way. Previous conceptual work on policy mixes has highlighted evaluative criteria such as "consistency" (the ability of multiple policy tools to reinforce rather than undermine each other in the pursuit of individual policy goals, "coherence" (or the ability of multiple policy goals to co-exist with each other in a logical fashion, and "congruence" (or the ability of multiple goals and instruments to work together in a uni-directional or mutually supportive fashion as important design principles and measures of optimality in policy mixes. And previous empirical work on the evolution of existing policy mixes has highlighted how these three criteria are often lacking in mixes which have evolved over time as well as those which have otherwise been consciously designed. This article revisits this early design work in order to more clearly assess the reasons why many existing policy mixes are sub-optimal and the consequences this has for thinking about policy formulation processes and the practices of policy design.

  15. 技术创新、溢出效应与最优环境政策组合%Technology Innovation, Spillover and Optimal Combination of Environmental Policies

    Institute of Scientific and Technical Information of China (English)

    郁培丽; 石俊国; 窦姗姗; 孙广生

    2014-01-01

    This paper analyzes the influence of policy instruments on firms ’ green technology innovation based on a three-stage game model .Results find that rate of emission tax and subsides on ER&D are conducive to firms ’ green technology innovation .Social optimal rate of corrective tax is lower than marginal social damage of pollu-tion, and increases with equilibrium output .Government should use combination tools of emission tax and sub-sides when the spillover of green technology is very high while government should use combination tools of emis -sion tax on polluting activities and research and development tax when spillover is low .When emission tax is ex-ogenous , the subsidy in competition consition is higher than the subsidy in collabrative innovation condition . Government should use the combination tools to promote green technical innovation , especially the collabrate in-novation , according to the industry spillover .%构建环境政策内生的三阶段博弈模型,分析存在技术溢出效应时,环境政策组合工具对企业绿色技术创新的影响。研究发现,排污税和研发补贴有利于企业进行绿色技术创新,两者组合可以实现社会福利最大化。社会最优排污税税率低于排污对社会的边际破坏程度,并随着均衡产量的增加而提高。在技术溢出效应较高时,政府采取排污税和补贴的组合工具,而当技术溢出效应较低时,政府采取排污税和研发税的组合工具。当排污税税率外生给定时,竞争创新情况下的政府补贴要高于协同创新情况下的政府补贴。政府应结合行业技术溢出特征,采取相应的税收与补贴结合的政策工具,并在知识产权保护的基础上,促进企业集群协同绿色技术创新。

  16. The Optimum Replacement of Weapon

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao; ZHANG Jin-chun

    2002-01-01

    The theory of LCC (Life Cycle Cost) is applied in this paper. The relation between the economic life of weapon and the optimum replacement is analyzed. The method to define the optimum replacement time of weapon is discussed.

  17. “以泵代阀”末端系统的能耗分析与系统优化%Energy consumption analysis and system optimization of replacing control valves by frequency controlled pumps in terminal system

    Institute of Scientific and Technical Information of China (English)

    潘云钢

    2011-01-01

    Taking a fresh air handling unit of central air conditioning system using replacing control valves by frequency controlled pumps as an example, calculates respective energy consumption of chilled water pump under the conditions of using electric butterfly valve, swing check valve and butterfly bivalve check valve at the outlet of chilled water pump. Analyses and compares the characteristics and energy consumption of the systems. Puts forward that replacing check valve by electric butterfly valve is in favour of decreasing energy consumption.%以集中空调系统的新风空调机组采用“以泵代阀”调节方式为例,计算水泵出口分别采用电动蝶阀、旋启式止回阀和蝶式双瓣止回阀三种不同阀件下的水泵供冷季节的能耗量,分析和比较系统的特点和能耗,提出用电动蝶阀替代止回阀有利于减少水泵能耗的观点.

  18. Power Plant Replacement Study

    Energy Technology Data Exchange (ETDEWEB)

    Reed, Gary

    2010-09-30

    This report represents the final report for the Eastern Illinois University power plant replacement study. It contains all related documentation from consideration of possible solutions to the final recommended option. Included are the economic justifications associated with the chosen solution along with application for environmental permitting for the selected project for construction. This final report will summarize the results of execution of an EPC (energy performance contract) investment grade audit (IGA) which lead to an energy services agreement (ESA). The project includes scope of work to design and install energy conservation measures which are guaranteed by the contractor to be self‐funding over its twenty year contract duration. The cost recovery is derived from systems performance improvements leading to energy savings. The prime focus of this EPC effort is to provide a replacement solution for Eastern Illinois University’s aging and failing circa 1925 central steam production plant. Twenty‐three ECMs were considered viable whose net impact will provide sufficient savings to successfully support the overall project objectives.

  19. Total disc replacement.

    Science.gov (United States)

    Vital, J-M; Boissière, L

    2014-02-01

    Total disc replacement (TDR) (partial disc replacement will not be described) has been used in the lumbar spine since the 1980s, and more recently in the cervical spine. Although the biomechanical concepts are the same and both are inserted through an anterior approach, lumbar TDR is conventionally indicated for chronic low back pain, whereas cervical TDR is used for soft discal hernia resulting in cervicobrachial neuralgia. The insertion technique must be rigorous, with precise centering in the disc space, taking account of vascular anatomy, which is more complex in the lumbar region, particularly proximally to L5-S1. All of the numerous studies, including prospective randomized comparative trials, have demonstrated non-inferiority to fusion, or even short-term superiority regarding speed of improvement. The main implant-related complication is bridging heterotopic ossification with resulting loss of range of motion and increased rates of adjacent segment degeneration, although with an incidence lower than after arthrodesis. A sufficiently long follow-up, which has not yet been reached, will be necessary to establish definitively an advantage for TDR, particularly in the cervical spine. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  20. REPLACEMENT OF FRENCH CARDS

    CERN Multimedia

    HR/SOC

    2001-01-01

    The French Ministry of Foreign Affairs has informed the Organization that it is shortly to replace all diplomatic cards, special cards and employment permits ('attestations de fonctions') now held by members of the personnel and their families. Between 2 July and 31 December 2001, these cards are to be replaced by secure, computerized equivalents. The old cards may continue to be used until 31 December 2001. For the purposes of the handover, members of the personnel must go personally to the cards office (33/1-015), in order to fill in a 'fiche individuelle' form, taking the following documents for themselves and members of their families already in possession of a French card : A recent identity photograph in 4.5 cm x 3.5 cm format. The French card in their possession. An A4 photocopy of the same French card, certified by the cards office as being a true copy. Those members of the personnel whose cards (and/or cards belonging to members of their families) are shortly due to expire, or have recently done...

  1. REPLACEMENT OF FRENCH CARDS

    CERN Multimedia

    Human Resources Division; Cards.Service@cern.ch

    2001-01-01

    The French Ministry of Foreign Affairs is currently replacing all diplomatic cards, special cards and employment permits («attestations de fonctions») held by members of the personnel and their families. These cards are replaced by secure, computerized equivalents. The old cards may no longer be used after 31 December 2001. For the purposes of the handover, members of the personnel must go personally to the cards office (33/1-015) between 8h30 and 12h30, in order to fill in a «fiche individuelle» form, taking the following documents for themselves and members of their families already in possession of a French card : A recent identity photograph in 4.5 cm x 3.5 cm format, the French card in their possession, an A4 photocopy of the same French card, certified by the cards office as being a true copy. Those members of the personnel whose cards (and/or cards belonging to members of their families) are shortly due to expire, or have recently done so, are also requested...

  2. REPLACEMENT OF FRENCH CARDS

    CERN Multimedia

    Human Resources Division

    2001-01-01

    The French Ministry of Foreign Affairs has informed the Organization that it is shortly to replace all diplomatic cards, special cards and employment permits ('attestations de fonctions') now held by members of the personnel and their families. Between 2 July and 31 December 2001, these cards are to be replaced by secure, computerized equivalents. The old cards may continue to be used until 31 December 2001. For the purposes of the handover, members of the personnel are asked to go to the cards office (33/1-015), taking the following documents for themselves and members of their families already in possession of a French card : A recent identity photograph in 4.5 cm x 3.5 cm format, The French card in their possession, an A4 photocopy of the same French card, certified by the cards office as being a true copy. Those members of the personnel whose cards (and/or cards belonging to members of their families) are shortly due to expire, or have recently done so, are also requested to take these items to the c...

  3. REPLACEMENT OF FRENCH CARDS

    CERN Multimedia

    Human Resources Division

    2001-01-01

    The French Ministry of Foreign Affairs has informed the Organization that it is shortly to replace all diplomatic cards, special cards and employment permits ('attestations de fonctions') now held by members of the personnel and their families. Between 2 July and 31 December 2001, these cards are to be replaced by secure, computerized equivalents. A 'personnel office' stamped photocopy of the old cards may continue to be used until 31 December 2001. For the purposes of the handover, members of the personnel must go personally to the cards office (33/1-015), between 8:30 and 12:30, in order to fill a 'fiche individuelle' form (in black ink only), which has to be personally signed by themselves and another separately signed by members of their family, taking the following documents for themselves and members of their families already in possession of a French card : A recent identity photograph in 4.5 cm x 3.5 cm format (signed on the back) The French card in their possession an A4 photocopy of the same Fre...

  4. Power Plant Replacement Study

    Energy Technology Data Exchange (ETDEWEB)

    Reed, Gary

    2010-09-30

    This report represents the final report for the Eastern Illinois University power plant replacement study. It contains all related documentation from consideration of possible solutions to the final recommended option. Included are the economic justifications associated with the chosen solution along with application for environmental permitting for the selected project for construction. This final report will summarize the results of execution of an EPC (energy performance contract) investment grade audit (IGA) which lead to an energy services agreement (ESA). The project includes scope of work to design and install energy conservation measures which are guaranteed by the contractor to be self-funding over its twenty year contract duration. The cost recovery is derived from systems performance improvements leading to energy savings. The prime focus of this EPC effort is to provide a replacement solution for Eastern Illinois University's aging and failing circa 1925 central steam production plant. Twenty-three ECMs were considered viable whose net impact will provide sufficient savings to successfully support the overall project objectives.

  5. Faster Replacement Paths

    CERN Document Server

    Williams, Virginia Vassilevska

    2010-01-01

    The replacement paths problem for directed graphs is to find for given nodes s and t and every edge e on the shortest path between them, the shortest path between s and t which avoids e. For unweighted directed graphs on n vertices, the best known algorithm runtime was \\tilde{O}(n^{2.5}) by Roditty and Zwick. For graphs with integer weights in {-M,...,M}, Weimann and Yuster recently showed that one can use fast matrix multiplication and solve the problem in O(Mn^{2.584}) time, a runtime which would be O(Mn^{2.33}) if the exponent \\omega of matrix multiplication is 2. We improve both of these algorithms. Our new algorithm also relies on fast matrix multiplication and runs in O(M n^{\\omega} polylog(n)) time if \\omega>2 and O(n^{2+\\eps}) for any \\eps>0 if \\omega=2. Our result shows that, at least for small integer weights, the replacement paths problem in directed graphs may be easier than the related all pairs shortest paths problem in directed graphs, as the current best runtime for the latter is \\Omega(n^{2.5...

  6. Power Plant Replacement Study

    Energy Technology Data Exchange (ETDEWEB)

    Reed, Gary

    2010-09-30

    This report represents the final report for the Eastern Illinois University power plant replacement study. It contains all related documentation from consideration of possible solutions to the final recommended option. Included are the economic justifications associated with the chosen solution along with application for environmental permitting for the selected project for construction. This final report will summarize the results of execution of an EPC (energy performance contract) investment grade audit (IGA) which lead to an energy services agreement (ESA). The project includes scope of work to design and install energy conservation measures which are guaranteed by the contractor to be self-funding over its twenty year contract duration. The cost recovery is derived from systems performance improvements leading to energy savings. The prime focus of this EPC effort is to provide a replacement solution for Eastern Illinois University’s aging and failing circa 1925 central steam production plant. Twenty-three ECMs were considered viable whose net impact will provide sufficient savings to successfully support the overall project objectives.

  7. Optimal Policies on Investment and Reinsurance Based on a Markov Regime Switching Model%马尔可夫机制转换模型下保险公司的最优投资及再保险策略

    Institute of Scientific and Technical Information of China (English)

    王伟; 甘少波

    2015-01-01

    The problem of optimal investment and reinsurance policies based on a Markov regime switching model is studied. The dynamics of a risky asset is assumed to follow a Markov-modulated geometry Brownian motion, and an optimal investment and reinsurance policy by maximizes the expected exponential utility of terminal wealth is obtained. The results indicate that regime switching has a significant effect on the optimal investment strategies. In the end, the numerical analysis is provided which presents the effect of the market interest rate and absolute risk aversion parameter on the optimal investment and reinsurance policies.%研究了马尔可夫机制转换模型下保险公司的最优投资及再保险策略问题。假定风险资产价格满足马尔可夫调制的几何布朗运动,得到了最终财富的指数期望效用最大准则下的最优投资和最优再保险策略。结果表明:市场的经济状态对最优投资策略有很大影响,并通过数值计算分析了模型中市场利率和绝对风险厌恶系数与最优投资策略和最优再保险策略的关系。

  8. Method for Determining Optimal Residential Energy Efficiency Retrofit Packages

    Energy Technology Data Exchange (ETDEWEB)

    Polly, B.; Gestwick, M.; Bianchi, M.; Anderson, R.; Horowitz, S.; Christensen, C.; Judkoff, R.

    2011-04-01

    Businesses, government agencies, consumers, policy makers, and utilities currently have limited access to occupant-, building-, and location-specific recommendations for optimal energy retrofit packages, as defined by estimated costs and energy savings. This report describes an analysis method for determining optimal residential energy efficiency retrofit packages and, as an illustrative example, applies the analysis method to a 1960s-era home in eight U.S. cities covering a range of International Energy Conservation Code (IECC) climate regions. The method uses an optimization scheme that considers average energy use (determined from building energy simulations) and equivalent annual cost to recommend optimal retrofit packages specific to the building, occupants, and location. Energy savings and incremental costs are calculated relative to a minimum upgrade reference scenario, which accounts for efficiency upgrades that would occur in the absence of a retrofit because of equipment wear-out and replacement with current minimum standards.

  9. Toleration, Synthesis or Replacement?

    DEFF Research Database (Denmark)

    Holtermann, Jakob v. H.; Madsen, Mikael Rask

    2016-01-01

    to have considerable problems keeping a clear focus on the key question: What are the implications of this empirical turn in terms of philosophy of legal science, of the social understanding of IL, and, not least, of the place of doctrinal scholarship after the alleged Wende? What is needed, we argue......, in order to answer is not yet another partisan suggestion, but rather an attempt at making intelligible both the oppositions and the possibilities of synthesis between normative and empirical approaches to law. Based on our assessment and rational reconstruction of current arguments and positions, we...... therefore outline a taxonomy consisting of the following three basic, ideal-types in terms of the epistemological understanding of the interface of law and empirical studies: toleration, synthesis and replacement. This tripartite model proves useful with a view to teasing out and better articulating...

  10. 易腐商品最优广告投入与订货策略的联合确定%Joint determination of optimal advertisement investment and order policy for perishable products

    Institute of Scientific and Technical Information of China (English)

    丁虹; 周永务

    2009-01-01

    In the traditional study of the perishable products problem and its extensions, the influence of advertisements has not been considered. However, in the process of practically selling merchandise, retailers often stimulate demand of items sold by them through advertisements. Therefore, it is important to research the influence of advertisements so as to make advertisement investment policy and order policy feasible. This paper considers the effect of advertisements on the perishable products problem and establishes a mathematical model of joint determination of optimal advertisement investment and order policy under the conditions of time-varying demands. An application example is given and the effect of the parameters of the model on the optimal policy is analyzed.%传统的易腐品问题及扩展研究都没有考虑到广告的影响,在实际的经销过程中,零售商经常通过广告手段来刺激需求;文章以持续变质的易腐品为研究对象,引入广告投入对单位时刻需求量的影响,建立了在时变需求下最优广告投入与订货策略联合确定的数学模型,扩展了已有的库存模型,更贴近实际;最后给出了应用实例,并分析了模型参数变化对最优策略的影响.

  11. Entrepreneurship Policies: Principles, Problems and Opportunities

    OpenAIRE

    Karlsson, Charlie; Andersson, Martin

    2009-01-01

    In this paper, we discuss the current status of the literature on entrepreneurship policy. The purpose is to discuss and assess several fundamental questions pertaining to entrepreneurship policies, such as “What is the optimal rate of entrepreneurship?” and “What entrepreneurship policies to pursue to remedy market failures and to avoid policy failures?”. In the entrepreneurship policies literature several contributors make distinctions between five types of entrepreneurship policy: governme...

  12. Test of ACW-gradient optimisation algorithm in computation of an optimal control policy for achieving acceptable nitrate concentration of greenhouse lettuce

    NARCIS (Netherlands)

    Graaf, de S.C.; Stigter, J.D.; Straten, van G.

    2004-01-01

    The adjustable control-variation weight (ACW)-gradient method proposed by Weinreb [Optimal Control with Multiple Bounded Inputs, Department of Electrical Engineering, Stanford University, Stanford, 1985, p. 148] is put to the test in finding optimal control laws for an optimisation problem with boun

  13. Optimal learning

    CERN Document Server

    Powell, Warren B

    2012-01-01

    Learn the science of collecting information to make effective decisions Everyday decisions are made without the benefit of accurate information. Optimal Learning develops the needed principles for gathering information to make decisions, especially when collecting information is time-consuming and expensive. Designed for readers with an elementary background in probability and statistics, the book presents effective and practical policies illustrated in a wide range of applications, from energy, homeland security, and transportation to engineering, health, and business. This book covers the

  14. 两种目标制下的我国最优货币政策研究%Research on Optimal Monetary Policies under Two Kinds of Target in China

    Institute of Scientific and Technical Information of China (English)

    谢戟; 赵新泉

    2015-01-01

    T his paper has established an AD‐AS model of open economy .It structures and estimates a mixed AD‐AS model based on statistics from 2003 to 2013 of China ,concluding optimal pre‐commitment monetary rules both of inflation target and interest rate smoothness target .Without interference ,the macro‐economy system of China would be asymptotically stable under both of the two optimal monetary policies .The optimal monetary policy of inflation target is more effective on controlling output gap ,w hile the policy of interest rate smoothness target is more sensible on operability .%文章构造了一个开放经济下的混合型AD‐AS模型,并根据我国2003~2013年的统计数据对其进行了估计,分别求出了在通货膨胀目标制和利率平滑目标制下事先承诺型的最优货币政策规则。在没有扰动的情况下,我国的宏观经济系统在这两种最优货币政策下都是渐近稳定的。通过两种目标制下最优货币政策的比较,发现在控制产出缺口方面,通货膨胀目标制更有效,在利率的操作性方面,利率平滑目标制更合理。

  15. Macronutrient replacement options for saturated fat: effects on cardiovascular health.

    Science.gov (United States)

    Flock, Michael R; Fleming, Jennifer A; Kris-Etherton, Penny M

    2014-02-01

    The purpose of this review is to discuss macronutrient replacement options for saturated fatty acids (SFAs) to optimize cardiovascular disease (CVD) risk reduction. Dietary recommendations advise decreasing SFAs. There is convincing evidence that replacing SFAs with unsaturated fat, both omega-6 and omega-3 polyunsaturated fatty acids, reduces CVD risk. Monounsaturated fatty acid substitution for SFAs also decreases CVD risk. Replacing SFAs with refined carbohydrate does little to alter CVD risk, whereas whole-grain CHO or lean protein substitutions beneficially affect CVD risk. Modifying the macronutrient composition of the diet by replacing SFAs with unsaturated fatty acids, as well as lean protein and carbohydrate from whole grains, all lower CVD risk. Research is needed to identify food sources of macronutrients that optimize CVD risk reduction.

  16. Comparative Multi-Criteria Assessment of Climate Policies and Sustainable Development Strategies in Cameroon: Towards a GIS Decision-Support Tool for the Design of an Optimal REDD+ Strategy

    Directory of Open Access Journals (Sweden)

    Anderson Gwanyebit Kehbila

    2014-09-01

    Full Text Available Cameroon is committed to reducing emissions from deforestation and forest degradation plus conservation, sustainable management of forests and enhancement of carbon stocks (REDD+. To achieve this goal, the government has introduced a series of policy reforms and formulated a number of key strategic planning documents to advance the REDD+ readiness process in Cameroon. This paper assesses the extent to which major cross-sectoral policies support or impede the development and implementation of an optimal REDD+ strategy in Cameroon from a comparative multi-criteria perspective. Study results reveal that a majority of the policy instruments reviewed appeared to be less prescriptive in terms of any tangible REDD+ strategy, as they do not have provisions for tangible measures to reduce deforestation and forest degradation. Given the lack of adequate flexibility, prompt review and responsiveness of these cross-sectoral policies to adapt themselves to new realities and respond to a changing environment, this paper introduces a GIS-REDD+ decision support system (GIS-REDD+DSS that is necessary to support the adaptive element of an adaptive REDD+ strategy in Cameroon. The GIS-REDD+DSS, an electronic REDD+agri intermediary hub, serves the following purpose: (1 host a database of locally-relevant climate information, improved input technologies, best practices as well as land use and forest cover geo-spatial maps; (2 host a virtual economic tool that performs economic valuations (costs and benefits and financial analysis of REDD+agri projects to aid investment decision-making; and (3 host an electronic marketplace to mediate any-to-any transactions among REDD+agri project developers, service providers, input suppliers, private and institutional investors and buyers (wholesalers and retailers, thereby creating value in two ways: aggregation and matching. This decision support tool, we argue, is a fundamental prerequisite for “policy and REDD+ safeguard

  17. Retention Benefit Based Intelligent Cache Replacement

    Institute of Scientific and Technical Information of China (English)

    李凌达; 陆俊林; 程旭

    2014-01-01

    The performance loss resulting from different cache misses is variable in modern systems for two reasons: 1) memory access latency is not uniform, and 2) the latency toleration ability of processor cores varies across different misses. Compared with parallel misses and store misses, isolated fetch and load misses are more costly. The variation of cache miss penalty suggests that the cache replacement policy should take it into account. To that end, first, we propose the notion of retention benefit. Retention benefits can evaluate not only the increment of processor stall cycles on cache misses, but also the reduction of processor stall cycles due to cache hits. Then, we propose Retention Benefit Based Replacement (RBR) which aims to maximize the aggregate retention benefits of blocks reserved in the cache. RBR keeps track of the total retention benefit for each block in the cache, and it preferentially evicts the block with the minimum total retention benefit on replacement. The evaluation shows that RBR can improve cache performance significantly in both single-core and multi-core environment while requiring a low storage overhead. It also outperforms other state-of-the-art techniques.

  18. Best practices and recommendations on policy packaging

    DEFF Research Database (Denmark)

    Fearnley, Nils; Longva, Frode; Ramjerdi, Farideh

    2011-01-01

    This report, which is the final deliverable of the Optic project (Optimal Policies for Transport In Combination), summarises two years of collaborative research into the policy process of combining individual measures into policy packages. Six stages of the policy process are identified. This rep...

  19. Effective Vaccination Policies.

    Science.gov (United States)

    Shaw, L; Spears, W; Billings, L; Maxim, P

    2010-10-01

    We present a framework for modeling the spread of pathogens throughout a population and generating policies that minimize the impact of those pathogens on the population. This framework is used to study the spread of human viruses between cities via airplane travel. It combines agent-based simulation, mathematical analysis, and an Evolutionary Algorithm (EA) optimizer. The goal of this study is to develop tools that determine the optimal distribution of a vaccine supply in the model. Using plausible benchmark vaccine allocation policies of uniform and proportional distribution, we compared their effectiveness to policies found by the EA. We then designed and tested a new, more effective policy which increased the importance of vaccinating smaller cities that are flown to more often. This "importance factor" was validated using U.S. influenza data from the last four years.

  20. Aligning and Inventing Practices to Achieve Inclusive Assessment Policies: A Decade of Work toward Optimal Access for US Students with Disabilities 2001-2011

    Science.gov (United States)

    Weigert, Susan C.

    2012-01-01

    The decade following the publication of the No Child Left Behind Act 2001 was an innovative period with respect to inclusive assessment practices for students with disabilities (SWDs). As the United States educational policies under the Obama Administration's Race to the Top initiative re-conceive the inclusion of SWDs in state assessment-based…

  1. 企业年金税收优惠政策国际比较及其借鉴%Enterprise annuity tax optimization policy international comparison and reference

    Institute of Scientific and Technical Information of China (English)

    刘军丽

    2012-01-01

    企业年金的税收优惠政策对于发展企业年金制度起着重要的作用。然而,我国的税收优惠政策在模式选择、优惠力度及监管体系方面都存在一些问题,使得企业年金制度发展受到制约。本文从企业年金税收优惠政策的国际比较入手,结合我国实际情况,探讨我国企业年金税收优惠政策的改进途径。%The favorable tax policy plays an important role to the Occupational Pension System.However,some key issues of the favorable tax policy such as mode selection,favorable power and supervision system remain unresolved and have hindered the development of the occupational pension system.By comparing the favorable tax policy of occupational pension in different countries and the practice in China,this paper provides some suggestions to the favorable tax policy of the Occupational Pension System in China.

  2. Optimal pricing and lot-sizing policies for an economic production quantity model with non-instantaneous deteriorating items, permissible delay in payments, customer returns, and inflation

    DEFF Research Database (Denmark)

    Ghoreishi, Maryam; Mirzazadeh, Abolfazl; Nakhai Kamalabadi, Isa

    2014-01-01

    This article deals with an economic production quantity inventory model for non-instantaneous deteriorating items under inflationary conditions, permissible delay in payments, customer returns, and price- and time-dependent demand. The customer returns are assumed as a function of demand and price....... The effects of time value of money are studied using the Discounted Cash Flow approach. The main objective is to determine the optimal selling price, the optimal length of the production period, and the optimal length of inventory cycle simultaneously such that the present value of total profit is maximized....... An efficient algorithm is presented to find the optimal solution of the developed model. Finally, a numerical example is extracted to solve the presented inventory model using our proposed algorithm, and the effects of the customer returns, inflation, and delay in payments are also discussed....

  3. Using your shoulder after replacement surgery

    Science.gov (United States)

    Joint replacement surgery - using your shoulder; Shoulder replacement surgery - after ... You have had shoulder replacement surgery to replace the bones of your shoulder joint with artificial parts. The parts include a stem made of metal and a ...

  4. Resorbable screws versus pins for optimal transplant fixation (SPOT in anterior cruciate ligament replacement with autologous hamstring grafts: rationale and design of a randomized, controlled, patient and investigator blinded trial [ISRCTN17384369

    Directory of Open Access Journals (Sweden)

    Rademacher Grit

    2005-02-01

    Full Text Available Abstract Background Ruptures of the anterior cruciate ligament (ACL are common injuries to the knee joint. Arthroscopic ACL replacement by autologous tendon grafts has established itself as a standard of care. Data from both experimental and observational studies suggest that surgical reconstruction does not fully restore knee stability. Persisting anterior laxity may lead to recurrent episodes of giving-way and cartilage damage. This might at least in part depend on the method of graft fixation in the bony tunnels. Whereas resorbable screws are easy to handle, pins may better preserve graft tension. The objective of this study is to determine whether pinning of ACL grafts reduces residual anterior laxity six months after surgery as compared to screw fixation. Design/ Methods SPOT is a randomised, controlled, patient and investigator blinded trial conducted at a single academic institution. Eligible patients are scheduled to arthroscopic ACL repair with triple-stranded hamstring grafts, conducted by a single, experienced surgeon. Intraoperatively, subjects willing to engage in this study will be randomised to transplant tethering with either resorbable screws or resorbable pins. No other changes apply to locally established treatment protocols. Patients and clinical investigators will remain blinded to the assigned fixation method until the six-month follow-up examination. The primary outcome is the side-to-side (repaired to healthy knee difference in anterior translation as measured by the KT-1000 arthrometer at a defined load (89 N six months after surgery. A sample size of 54 patients will yield a power of 80% to detect a difference of 1.0 mm ± standard deviation 1.2 mm at a two-sided alpha of 5% with a t-test for independent samples. Secondary outcomes (generic and disease-specific measures of quality of life, magnetic resonance imaging morphology of transplants and devices will be handled in an exploratory fashion. Conclusion SPOT aims at

  5. Educating My Replacement

    Science.gov (United States)

    Tarter, Jill

    , in partnership with the dedicated teachers out there, I think I can help promote the critical thinking skills and scientific literacy of the next generation of voters. Hopefully, I can also help train my replacement to be a better scientist, capable of seizing all the opportunities generated by advances in technology and our improved understanding of the universe to craft search strategies with greater probability of success than those I have initiated.

  6. Optimal advertisement cost and order policy for Newsboy-type-merchandise under the CVaR criterion%基于CVaR准则的Newsboy型商品最优广告费用与订货策略

    Institute of Scientific and Technical Information of China (English)

    李绩才; 周永务; 钟远光

    2012-01-01

    The standard Newsboy problem is based upon risk neutrality with an objective of maximizing expected profit or minimizing expected cost. In this paper, we consider the optimal advertisement cost and order policy under the conditional value-at-risk (CVaR) criterion in a Newsboy model, in which the retailer is risk averse and faces a random demand depending on advertising expenditure. We analyse the effect of risk aversion, the uncertainty in demand, and the merchandise nature on the optimal advertisement investment cost and order quantity decision. And then we illustrate our findings by some numerical examples. These results will be helpful for retailers to make advertisement investment policy, and order policy feasibly and scientifically.%研究了风险厌恶型零售商在面对随机市场需求与广告投入相关时的最优广告投入与订货策略.通过乘法需求形式将广告投入对需求的影响引入Newsboy问题中,并以CVaR作为风险度量准则,建立了风险厌恶型零售商广告投入与订货量联合决策的随机模型;揭示了风险厌恶程度、需求不确定性以及商品本身特性对零售商最优广告投入和订货量的影响;最后通过应用实例对理论结果进行了验证分析.研究结果为零售商制订广告投入策略和相应的订货策略提供了参考.

  7. [Ascending aorta replacement late after aortic valve replacement].

    Science.gov (United States)

    Hayashi, Yasunari; Ito, Toshiaki; Maekawa, Atsuo; Sawaki, Sadanari; Fujii, Genyo; Hoshino, Satoshi; Tokoro, Masayoshi; Yanagisawa, Junji

    2013-07-01

    Replacement of the asceding aorta is indicated in patients undergoing aortic valve replacement( AVR), if the diameter of the ascending aorta is greater than 5.0 cm. If the diameter of the asceding aorta is from 4.0 to 5.0 cm, it was arguable whether replacement of the ascending aorta should be performed. Nine patients who underwent reoperative ascending aorta replacement after AVR were reviewed retrospectively. Reoperation on the asending aorta replacement was performed 11.8±7.2 years (range 1y5m~23y3m) after AVR. Mean patient age was 69.9±6.3 (range 60~81). In 2 cases, reoperations were performed early year after AVR. Although ascending aorta was dilated at the 1st operation, replacement wasn't performed for the age and minimally invasive cardiac surgery (MICS). In 3 cases, reoperations were performed more than 10 years later. On these cases, ascending aorta aneurysm and dissection occurred with no pain and were pointed out by computed tomography(CT) or ultrasonic cardiogram(UCG). We think that patients with dilatation of the ascending aorta should undergo AVR and aorta replacement at the 1st operation regardness of age. It is important that patients who underwent AVR should undergo a regular checkup on the ascending aorta.

  8. Ramsey monetary policy with labour market frictions

    OpenAIRE

    Faia, Ester

    2007-01-01

    This paper studies the design of optimal monetary policy (in terms of unconstrained Ramsey allocation) in a framework with sticky prices and matching frictions. Furthermore I consider the role of real wage rigidities. Optimal policy features significant deviations from price stability in response to various shocks. This is so since search externalities generate an unemployment/inflation trade-off. In response to productivity shocks optimal policy is pro-cyclical when the worker’s bargaining p...

  9. Cumulative Innovation,the Protection Decision to Intellectual Property Rights and Optimal Policy%累积性创新、知识产权保护策略与最优政策

    Institute of Scientific and Technical Information of China (English)

    夏玉华

    2015-01-01

    建立了一个两阶段研发(R&D)竞赛模型,分析在累积性创新市场上厂商选择不同知识产权保护策略对其创新决策及最优政策的影响。研究表明:当商业秘密能够作为创新的有效保护机制时,政府应该对初始创新实行宽专利保护政策,以刺激创新信息的披露;如果此时专利政策仍不能奏效,那么政府就应该实行宽松的反垄断政策,允许初始创新者和后续创新者达成同盟协议。%Built a two stages of development (R&D)race model,analysis of the impact of firms in the cumulative innova-tion market on different intellectual property protection strategies on the innovation decision and optimal policy.Research shows that,when the trade secret can be used as the effective protection of innovation mechanism,the government should implement a wide patent protection policy to the initial innovation,to stimulate the innovation of information disclosure.If the patent policy still does not work,so the government should be looser antitrust policy,allowing the initial innovator and subsequent innovators alliance to reach agreement.

  10. 我国农民专业合作社税收政策优化研究%A Study on the Optimization of the Tax Policy in Farmers Cooperatives in China

    Institute of Scientific and Technical Information of China (English)

    倪国锋

    2012-01-01

    The government of China have formulated a series of tax preferential policies to support the healthy and rapid development of farmers cooperatives in recent years. Current tax policies have many issues, so govern- ment should learn from the advanced experience of developed countries, and optimize tax policy on the basis of fully research. The following measures should be taken : to perfect preferential policies of value - added tax and income tax;to solve the double burden of cooperatives;to establish and strengthen the level of accounting and financial man- agement;to improve the scientific and technological level of farmers'cooDeratives.%近年来我国政府在税收方面制定了一系列的优惠政策来支持农民合作社的健康快速发展,但现行税收政策存在诸多问题。政府应在充分调研的基础上,借鉴发达国家先进经验,进一步优化农民专业合作社税收政策。具体建议有:完善增值税和所得税优惠政策;解决合作社双重负担问题;健全会计核算,提高财务管理水平以及提高农民专业合作社的科技水平等。

  11. An optimal policy for deteriorating items with time-proportional deterioration rate and constant and time-dependent linear demand rate

    Science.gov (United States)

    Singh, Trailokyanath; Mishra, Pandit Jagatananda; Pattanayak, Hadibandhu

    2017-04-01

    In this paper, an economic order quantity (EOQ) inventory model for a deteriorating item is developed with the following characteristics: (i) The demand rate is deterministic and two-staged, i.e., it is constant in first part of the cycle and linear function of time in the second part. (ii) Deterioration rate is time-proportional. (iii) Shortages are not allowed to occur. The optimal cycle time and the optimal order quantity have been derived by minimizing the total average cost. A simple solution procedure is provided to illustrate the proposed model. The article concludes with a numerical example and sensitivity analysis of various parameters as illustrations of the theoretical results.

  12. Cultural Policy in Iceland

    DEFF Research Database (Denmark)

    Gudmundsson, Gestur

    2003-01-01

    The article examines the history of cultural policy in Iceland from a Nordic comparative perspective. National cultural policy takes form in the 19th and early 20th century as a part of the nation-building, emphasising the Icelandic language as the core of national identity, building cultural...... on the continuing emphasis on central cultural institution and the Icelandic language. Since the 1970s Cold War conflicts have been replaced by a consensus on growing support to artists and an armth's length policy, and furthermore the 1990s have seen a strong move towards NPM and international participation....... institutions and relying heavily on civic society enterprise. After national independence in 1918 there are growing conflicts in the cultural field and during the Cold War such conflicts take the form of an alliance of nationlism and socialism against NATO-oriented anti-communism. However, there is consensus...

  13. New staff contract policy

    CERN Multimedia

    HR Department

    2006-01-01

    Following discussion at TREF and on the recommendation of the Finance Committee, Council approved a new staff contract policy, which became effective on 1 January 2006. Its application is covered by a new Administrative Circular No. 2 (Rev. 3) 'Recruitment, appointment and possible developments regarding the contractual position of staff members'. The revised circular replaces the previous Circulars No. 9 (Rev. 3) 'Staff contracts' and No. 2 (Rev. 2) 'Guidelines and procedures concerning recruitment and probation period for staff members'. The main features of the new contract policy are as follows: The new policy provides chances for long-term employment for all staff recruits staying for four years without distinguishing between those assigned to long-term or short-term activities when joining CERN. In addition, it presents a number of simplifications for the award of ICs. There are henceforth only 2 types of contract: Limited Duration (LD) contracts for all recruitment and Indefinite Contracts (IC) for...

  14. 考虑个体保单风险特征的最优奖惩系统%Optimal Bonus-malus Systems Accounting for Risk Characteristics of Individual Policies

    Institute of Scientific and Technical Information of China (English)

    孟生旺

    2013-01-01

    BMS is widely used in aotu insurance.The paper first discusses the optimal BMS and its properties under the Poisson-Gamma assumption.Then under the assumption that the claim frequency of a policyholder follows Binomial distribution and one parameter of the Binomial distribution is varying according to Beta distribution,the paper establishes an optimal bonus-malus system that can account for prior information of individual policies.The prior information can be introduced to the optimal bonus-malus system by generalized linear model.Under the assumption that the claim frequency of a policyholder follows Negative Binomial distribution and one parameter of the Negative Binomial is Beta distributed,another optimal bolus-malus system accounting for prior information of individual policies is established.The properties and applications of these optimal bonus-malus systems are also discussed.%奖惩系统在汽车保险中的应用非常普遍.论文首先介绍和讨论了泊松-伽马假设下的最优奖惩系统及其性质;其次在假设个体保单的索赔频率服从二项分布,而二项分布的一个参数服从贝塔分布的条件下,建立了一种考虑个体保单风险特征信息的最优奖惩系统,其中风险特征信息可以通过广义线性模型的形式引入奖惩系统;然后在假设个体保单的索赔频率服从负二项分布,而负二项分布的一个参数服从贝塔分布的条件下,建立了另一个最优奖惩系统;最后讨论了这两个奖惩系统的性质和应用.

  15. Electrocatalysts Prepared by Galvanic Replacement

    OpenAIRE

    Athanasios Papaderakis; Ioanna Mintsouli; Jenia Georgieva; Sotiris Sotiropoulos

    2017-01-01

    Galvanic replacement is the spontaneous replacement of surface layers of a metal, M, by a more noble metal, Mnoble, when the former is treated with a solution containing the latter in ionic form, according to the general replacement reaction: nM + mMnoblen+ → nMm+ + mMnoble. The reaction is driven by the difference in the equilibrium potential of the two metal/metal ion redox couples and, to avoid parasitic cathodic processes such as oxygen reduction and (in some cases) hydrogen evolution too...

  16. Controversy in mitral valve repair, resection or chordal replacement?

    Science.gov (United States)

    Sawazaki, Masaru; Tomari, Shiro; Zaikokuji, Kenta; Imaeda, Yusuke

    2014-10-01

    Mitral valve plasty has superseded valve replacement as the standard technique for treating degenerative mitral valve prolapse. Quadrangular resection is considered the gold standard for posterior leaflet prolapse. Chordal replacement was first developed to treat the anterior leaflet and subsequently became widely used for the posterior leaflet, after which a new version of posterior leaflet resection was developed that did not involve local annular plication. In the era of the mini-thoracotomy, the premeasured loop technique is simple to adopt and is as durable as quadrangular resection. However, there is controversy surrounding whether resection or chordal replacement is the optimal technique. The resection technique is curative because it removes the main pathologic lesion. The disadvantage of the resection is that it can be complicated and often requires advanced surgical skills. In contrast, chordal replacement is not pathologically curative because it leaves behind a redundant leaflet. However, the long-term results appear to be equivalent in many reports. Functionally, chordal replacement retains greater posterior leaflet motion with a lower trans-mitral pressure gradient than quadrangular resection. Moreover, chordal replacement is simple and yields uniform results. The optimal technique depends on whether the anterior leaflet or posterior leaflet is involved, the Barlow or non-Barlow disease state, and whether a mini-thoracotomy or standard sternotomy approach is used. For mitral valve repair, the most superior and reliable technique for the posterior leaflet is resection using the newer resection technique with a sternotomy approach, which requires a skilled surgeon.

  17. Minimally invasive aortic valve replacement

    DEFF Research Database (Denmark)

    Foghsgaard, Signe; Schmidt, Thomas Andersen; Kjaergard, Henrik K

    2009-01-01

    In this descriptive prospective study, we evaluate the outcomes of surgery in 98 patients who were scheduled to undergo minimally invasive aortic valve replacement. These patients were compared with a group of 50 patients who underwent scheduled aortic valve replacement through a full sternotomy....... The 30-day mortality rate for the 98 patients was zero, although 14 of the 98 mini-sternotomies had to be converted to complete sternotomies intraoperatively due to technical problems. Such conversion doubled the operative time over that of the planned full sternotomies. In the group of patients whose...... is an excellent operation in selected patients, but its true advantages over conventional aortic valve replacement (other than a smaller scar) await evaluation by means of randomized clinical trial. The "extended mini-aortic valve replacement" operation, on the other hand, is a risky procedure that should...

  18. 保险公司的最优投资与一般再保险策略%OPTIMAL AND GENERAL REINSURANCE POLICIES FOR INSURANCE COMPANY

    Institute of Scientific and Technical Information of China (English)

    赵守娟; 杨青龙; 庄乐森

    2012-01-01

    本文研究了在股票价格服从几何布朗运动的假设下,原保公司考虑再保险时的最优投资问题.运用动态规划和鞅方法,得到了一般最优控制问题所满足的HJB方程以及该方程的识别定理,并分别对比例再保险和超额再保险做了详细分析.%The optimal investment strategy with the general reinsurance strategy of the original insurance company is considered when the stock price is modeled by geometric Brownian motion. By using the dynamic programming and the martingale principle, we obtain the HJB equation of the optimal control and its the verification theorem and analyze the examples of proportional reinsurance and excess of loss reinsurance.

  19. National Athletic Trainers' Association Position Statement: Fluid Replacement for Athletes.

    Science.gov (United States)

    Case, Douglas J.; Armstrong, Lawrence E.; Hillman, Susan K.; Montain, Scott J.; Reiff, Ralph V.; Rich, Brent S. E.; Roberts, William O.; Stone, Jennifer A.

    2000-01-01

    Presents recommendations from the National Athletic Trainers Association for optimizing the fluid replacement practices of athletes, explaining that dehydration can compromise athletic performance and increase the risk of exertional heat injury. Athletes must be educated about the risks of dehydration and overhydration. They must learn fluid…

  20. Policy Overview and Options for Maximizing the Role of Policy in Geothermal Electricity Development

    Energy Technology Data Exchange (ETDEWEB)

    Doris, Elizabeth [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kreycik, Claire [National Renewable Energy Lab. (NREL), Golden, CO (United States); Young, Katherine [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2009-09-01

    This research explores the effectiveness of the historical and current body of policies in terms of increased geothermal electricity development. Insights are provided into future policies that may drive the market to optimize development of available geothermal electricity resources.

  1. The Second-Best Optimal Effect on the Combination of Environmental Policy Instruments%环境政策工具组合的次优改进效应

    Institute of Scientific and Technical Information of China (English)

    郭宏宝; 朱志勇

    2016-01-01

    政府通常利用政策组合实现环境治理目标, 许多文献研究了这种实践的次优改进特征. 通过构建理论模型, 研究管制政策与税收政策组合的次优改进及其实现方法, 结果表明在信息不完全的情况下, 对产生较大边际外部成本的行为予以管制, 则税收政策与管制政策的组合比单独使用某个政策更具效率, 此时, 税率为边际社会成本的加权平均, 管制通过边际社会成本和权重来影响税率的设定, 进而实现税收与管制政策的协同. 理论模型的启示是: 合理使用政策组合有利于更好地实现环境治理目标.对此, 基于浙江省 "五水共治" 的治污实践, 运用该省化纤行业的数据验证了本文的研究结论.%The target of environmental management is usually realized by the policy combination used by gov-ernment ,many literatures studied the second-best optimal features of this practice.This paper constructs a theoreti-cal model,researches the second-best improvement of the combination of control and tax policy instrument.The re-sults show that under incomplete information,when the larger marginal external cost behavior is regulated,a combi-nation of tax and regulatory policy is more efficient than the single one,the tax rate should be a weighted average of the marginal social cost,and regulation affects the tax rate through the marginal social cost and the weight,which bring about the coordination of tax and regulation policy.The enlightenment of theoretical model is that it is reasona-ble to use the policy combination to realize the target of environmental management in practice.At the end of this paper,the theoretical conclusion is verified using the chemical fiber industry data of Zhejiang province based on its water pollution control practice.

  2. Joint Optimization of Condition-based Preventive Maintenance and Spare Parts Provisioning Policy for Equipment Maintenance%设备视情预防维修与备件订购策略的联合优化

    Institute of Scientific and Technical Information of China (English)

    张晓红; 曾建潮

    2015-01-01

    A jointly condition-based preventive maintenance and spare parts provisioning policy is discussed for equipment maintenance. Based on analysis of all possible transitions of the joint state of equipment and its spare parts inventory, the explicit expression of stationary joint probability density function is derived and its numerical solution is deduced. On the basis of the joint probability density function, the maintenance probabilities of the equipment with the influence of spare parts inventory and the ordering and holding probabilities of its spare parts are derived. Then the expected long-run cost rate model is formulated for the joint policy using the renewal process, taking into account the costs incurred for performing maintenance and managing the spare parts inventory. A numerical experiment is carried out to identify the optimal values for the parameters of the policy, including the inspection interval, the ordering threshold, and the preventive maintenance threshold. The experiment results verify that the derivation of the joint probability density function is correct and the established model is effective. The results of the sensitivity analysis show that a trade-off exists between the maintenance related costs and the inventory related costs, and joint optimization of preventive maintenance and spare parts provisioning policy can ensure a global optimal policy. A practical case is provided to verify the effectiveness of the proposed method.%研究设备的视情预防维修与备件订购策略的联合优化问题.在分析设备劣化与备件库存联合状态转换的基础上,给出了联合状态的稳态概率密度函数的显式表达式和数值求解方法.基于此联合概率密度函数,推导连续劣化的设备受备件库存状态影响的维修概率和备件的订购和持有概率,建立以设备的检测周期、备件订购阈值、预防维修阈值为决策变量,同时考虑维修和备件相关成本的长期平均费用率

  3. An extended EPQ-based problem with a discontinuous delivery policy, scrap rate, and random breakdown.

    Science.gov (United States)

    Chiu, Singa Wang; Lin, Hong-Dar; Song, Ming-Syuan; Chen, Hsin-Mei; Chiu, Yuan-Shyi P

    2015-01-01

    In real supply chain environments, the discontinuous multidelivery policy is often used when finished products need to be transported to retailers or customers outside the production units. To address this real-life production-shipment situation, this study extends recent work using an economic production quantity- (EPQ-) based inventory model with a continuous inventory issuing policy, defective items, and machine breakdown by incorporating a multiple delivery policy into the model to replace the continuous policy and investigates the effect on the optimal run time decision for this specific EPQ model. Next, we further expand the scope of the problem to combine the retailer's stock holding cost into our study. This enhanced EPQ-based model can be used to reflect the situation found in contemporary manufacturing firms in which finished products are delivered to the producer's own retail stores and stocked there for sale. A second model is developed and studied. With the help of mathematical modeling and optimization techniques, the optimal run times that minimize the expected total system costs comprising costs incurred in production units, transportation, and retail stores are derived, for both models. Numerical examples are provided to demonstrate the applicability of our research results.

  4. A condition-based maintenance policy with non-periodic inspections for a two-unit series system

    Energy Technology Data Exchange (ETDEWEB)

    Castanier, B. [IRCCyN/Ecole des Mines de Nantes, Departement Automatique et Productique, 4 rue Alfred Kastler, F-44307 Nantes (France)]. E-mail: bruno.castanier@emn.fr; Grall, A. [Universite de Technologie de Troyes, ISTIT-CNRS FRE 2732, Equipe Modelisation et Surete des Systemes, 12, rue Marie Curie, BP 2060-10010 Troyes Cedex (France)]. E-mail: antoine.grall@utt.fr; Berenguer, C. [Universite de Technologie de Troyes, ISTIT-CNRS FRE 2732, Equipe Modelisation et Surete des Systemes, 12, rue Marie Curie, BP 2060-10010 Troyes Cedex (France)]. E-mail: christophe.berenguer@utt.fr

    2005-01-01

    This paper considers a condition-based maintenance policy for a two-unit deteriorating system. Each unit is subject to gradual deterioration and is monitored by sequential non-periodic inspections. It can be maintained by good as new preventive or corrective replacements. Every inspection or replacement entails a set-up cost and a component-specific unit cost but if actions on the two components are combined, the set-up cost is charged only once. A parametric maintenance decision framework is proposed to coordinate inspection/replacement of the two components and minimize the long-run maintenance cost of the system. A stochastic model is developed on the basis of the semi-regenerative properties of the maintained system state and the associated cost model is used to assess and optimize the performance of the maintenance model. Numerical experiments emphasize the interest of a control of the operation groupings.

  5. 具有固定成本优势的在位企业的最优许可策略%Optimal Licensing Policy for an Incumbent Firm with Fixed Cost Advantage

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper primarily focuses on two problems which aim at improving the results of the recent work of Yi S. S. (Yi S. S.,Entry, licensing and research joint ventures, International Journal of Industrial Organization, 1999,17:1-24). Firstyly, two improper viewpoints are pointed out and rectified. Under his model, Yi argued that the potential entrants can be better off or worse off under the incumbent firm's strategic use of ex-post licensing policy, but it is shown in this paper that the strategic licensing undoubtedly reduces the entrants'expected payoffs. Yi also noted wrongly that industry profit is a convex function of the number of firms in the product market by the Cournot oligopoly with a linear demand and constant marginal costs. However, in this paper it is demonstrated that industry profit in such a market is a concave-convex function of the number of firms. Secondly, a thorough study of the optimal licensing policy for the incumbent is made on the basis of the correction of the second error. Necessary and sufficient conditions under which the incumbent will choose ex-post licensing, ex-ante licensing of one entrant or ex-ante licensing of both extrants are given.

  6. A Study of Optimizing Course Teaching of Situation and Policy%高校《形势与政策》教学问题的优化路径研究

    Institute of Scientific and Technical Information of China (English)

    唐金权

    2016-01-01

    In response to the changing domestic and international situations, it is necessary to set up the course of Sit-uation and Policy in universities. Optimizing the teaching of the course is a realistic path to improve the level of Situ-ation and Policy teaching as it can guide the university students to view the important domestic and international problems correctly, understand their own historical mission and social responsibility, and firm their confidence and determination of socialism with Chinese characteristic.%针对不断发展变化的国内外形势,在高校大学生中进行《形势与政策》教学是非常必要的。优化《形势与政策》教学,是切实提高《形势与政策》教学水平的现实路径,能够引导大学生正确看待国内外重大的热点和难点问题,认识自己的历史使命和社会责任,坚定大学生走中国特色社会主义道路的信心和决心。

  7. Reliability Growth Modeling and Optimal Release Policy Under Fuzzy Environment of an N-version Programming System Incorporating the Effect of Fault Removal Efficiency

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Failure of a safety critical system can lead to big losses. Very high software reliability is required for automating the working of systems such as aircraft controller and nuclear reactor controller software systems. Fault-tolerant softwares are used to increase the overall reliability of software systems. Fault tolerance is achieved using the fault-tolerant schemes such as fault recovery (recovery block scheme), fault masking (N-version programming (NVP)) or a combination of both (Hybrid scheme). These softwares incorporate the ability of system survival even on a failure. Many researchers in the field of software engineering have done excellent work to study the reliability of fault-tolerant systems. Most of them consider the stable system reliability. Few attempts have been made in reliability modeling to study the reliability growth for an NVP system. Recently, a model was proposed to analyze the reliability growth of an NVP system incorporating the effect of fault removal efficiency. In this model, a proportion of the number of failures is assumed to be a measure of fault generation while an appropriate measure of fault generation should be the proportion of faults removed. In this paper, we first propose a testing efficiency model incorporating the effect of imperfect fault debugging and error generation. Using this model, a software reliability growth model (SRGM) is developed to model the reliability growth of an NVP system. The proposed model is useful for practical applications and can provide the measures of debugging effectiveness and additional workload or skilled professional required. It is very important for a developer to determine the optimal release time of the software to improve its performance in terms of competition and cost. In this paper, we also formulate the optimal software release time problem for a 3VP system under fuzzy environment and discuss a the fuzzy optimization technique for solving the problem with a numerical illustration.

  8. Optimal time policy for deteriorating items of two-warehouse inventory system with time and stock dependent demand and partial backlogging

    Indian Academy of Sciences (India)

    SHIV KUMAR; ABHAY KUMAR SINGH

    2016-05-01

    We consider the problem of a two-warehouse inventory system under the effect of stock dependent demand. There are two warehouses to store the goods in which the first is rented warehouse and the second is own warehouse that deteriorates with two different rates. The aim of this study is to determine the optimal order quantity to maximize the profit of the projected model. Finally, some numerical examples and sensitivity analysis of parameters are made to validate the results of the proposed model.

  9. Knee Replacement: What you can Expect

    Science.gov (United States)

    ... improves function lessen with each additional surgery. Artificial knees can wear out Another risk of knee replacement ... replacement surgery to last about two hours. After knee replacement surgery After surgery, you're wheeled to ...

  10. Homologous gene replacement in Physarum

    Energy Technology Data Exchange (ETDEWEB)

    Burland, T.G. [Univ. of Wisconsin, Madison, WI (United States); Pallotta, D. [Laval Univ., Quebec (Canada)

    1995-01-01

    The protist Physarum polycephalum is useful for analysis of several aspects of cellular and developmental biology. To expand the opportunities for experimental analysis of this organism, we have developed a method for gene replacement. We transformed Physarum amoebae with plasmid DNA carrying a mutant allele, ardD{Delta}1, of the ardD actin gene; ardD{Delta}1 mutates the critical carboxy-terminal region of the gene product. Because ardD is not expressed in the amoeba, replacement of ardD{sup +} with ardD{Delta}1 should not be lethal for this cell type. Transformants were obtained only when linear plasmid DNA was used. Most transformants carried one copy of ardD{Delta}1 in addition to ardD{sup +}, but in two (5%), ardD{sup +} was replaced by a single copy of ardD{Delta}1. This is the first example of homologous gene replacement in Physarum. ardD{Delta}1 was stably maintained in the genome through growth, development and meiosis. We found no effect of ardD{Delta}l on viability, growth, or development of any of the various cell types of Physarum. Thus, the carboxy-terminal region of the ardD product appears not to perform a unique essential role in growth or development. Nevertheless, this method for homologous gene replacement can be applied to analyze the function of any cloned gene. 38 refs., 6 figs., 1 tab.

  11. Policy Problematization

    Science.gov (United States)

    Webb, P. Taylor

    2014-01-01

    This article places Michel Foucault's concept of "problematization" in relation to educational policy research. My goal is to examine a key assumption of policy related to "solving problems" through such technologies. I discuss the potential problematization has to alter conceptions of policy research; and, through this…

  12. Policy Problematization

    Science.gov (United States)

    Webb, P. Taylor

    2014-01-01

    This article places Michel Foucault's concept of "problematization" in relation to educational policy research. My goal is to examine a key assumption of policy related to "solving problems" through such technologies. I discuss the potential problematization has to alter conceptions of policy research; and, through this…

  13. 随机提前期下考虑循环取货的最优采购策略%Optimal Procurement Policies Considering Milk-Run Delivery with Stochastic Lead Time

    Institute of Scientific and Technical Information of China (English)

    周欣; 霍佳震

    2011-01-01

    To cope with small lot sizes and frequent deliveries in lean logistics, manufacturers have the choices of direct shipping or milk runs in inbound logistics. The variances of total lead time caused by the uncertainty in each supplier's production processes are different in these two delivery modes and directly affect the optimal procurement policies and the choices of delivery modes. A multi-item supply chain consisting of one manufacturer and multiple suppliers was considered. Considering the effect of variance of total lead time on procurement policies and the choices of delivery modes, we develop inventories models based on stochastic lead time and limited capacities in direct shipping and milk runs, respectively, and obtain the optimal procurement policies. A numerical example is presented to illustrate the results. Comparing the effect of parameter change on the total costs, the conditions are given for these two delivery modes.%为适应精益化物流小批量、多频次的配送作业运作要求,很多企业在供应物流环节面临着是循环取货还是直接运输的选择.配送过程中各供应商生产过程的不确定性导致了总提前期的波动,由于在2种配送方式下总提前期的波动不同,因此,提前期的波动直接影响到最优采购策略以及配送方式的选择.以由制造商和多供应商组成的多产品供应链为背景展开研究,考虑到提前期的波动对采购方式和采购策略的影响,基于随机提前期且考虑车载量约束,分别建立了直接运输和循环取货2种配送方式下的库存优化模型,并进一步求解得出了各自的最优采购策略.最后,通过数值分析对上述研究结果进行了论证,并比较了参数变化对2种配送方式下总成本的影响,给出了2种配送方式的具体适用条件.

  14. Disaster Risks, Welfare Costs and the Optimal Disaster Relief Policy of Government%灾害风险、福利损失与政府最优救助计划

    Institute of Scientific and Technical Information of China (English)

    田玲; 高俊

    2012-01-01

    To study the optimal relief behavior of the government, we introduce a dynamic stochastic control model which considers the catastrophe risk, consumers' risk preference, budget constraint, and the government's fiscal costs. The model shows that the optimal relief behavior of the government is a trade-off between the benefit of the consumers' welfare and the government' s fiscal costs. And it exits multidimensional optimal frontiers of the government behavior. That is to say, the optimal subsidy scales are different if the change occurs among the param-eters, even if they are the uniform catastrophe. Consequently, there are conclusions following: Firstly, the larger of the loss the catastrophe cause, the worse of the anti-disaster ability consumers' have. It would lead to larger optimal subsidy scale, and the government financial burden is heavier. Secondly, the more consumers disguise risk, the more carefully they make the decision. And it would bring about more compensation required for the catastrophe loss. Hence the scale of the optimal relief policy would be larger. It is to pay more money for the government. Thirdly, if the production of our economy is more effective, the optimal relief scale would be less, and the money which the government pays for the catastrophe would be less too. Finally, the appropriate relief (optimal relief) scale help to improve the level of social welfare. Following the increasing risk aversion, the effects of the govern-ment relief to the catastrophe are better.According to our conclusion, to reduce expenditure, heighten the relief effects, improve the whole social welfare, we make some recommendations, such as strengthening the Riskbearing capacity, improving production efficiency, as well as reducing the catastrophe loss. And we see that the government should take three measures to re-live their catastrophe assistance pressure. First of all, the government should encourage people transfer the stress of risk

  15. Life cycle thinking and assessment tools on environmentally-benign electronics: Convergent optimization of materials use, end-of-life strategy and environmental policies

    Science.gov (United States)

    Zhou, Xiaoying

    The purpose of this study is to integrate the quantitative environmental performance assessment tools and the theory of multi-objective optimization within the boundary of electronic product systems to support the selection among design alternatives in terms of environmental impact, technical criteria, and economic feasibility. To meet with the requirements that result from emerging environmental legislation targeting electronics products, the research addresses an important analytical methodological approach to facilitate environmentally conscious design and end-of-life management with a life cycle viewpoint. A synthesis of diverse assessment tools is applied on a set of case studies: lead-free solder materials selection, cellular phone design, and desktop display technology assessment. In the first part of this work, an in-depth industrial survey of the status and concerns of the U.S. electronics industry on the elimination of lead (Pb) in solders is described. The results show that the trade-offs among environmental consequences, technology challenges, business risks, legislative compliance and stakeholders' preferences must be explicitly, simultaneously, and systematically addressed in the decision-making process used to guide multi-faceted planning of environmental solutions. In the second part of this work, the convergent optimization of the technical cycle, economic cycle and environmental cycle is addressed in a coherent and systematic way using the application of environmentally conscious design of cellular phones. The technical understanding of product structure, components analysis, and materials flow facilitates the development of "Design for Disassembly" guidelines. A bottom-up disassembly analysis on a "bill of materials" based structure at a micro-operational level is utilized to select optimal end-of-life strategies on the basis of economic feasibility. A macro-operational level life cycle model is used to investigate the environmental consequences

  16. Cobra Probes Containing Replaceable Thermocouples

    Science.gov (United States)

    Jones, John; Redding, Adam

    2007-01-01

    A modification of the basic design of cobra probes provides for relatively easy replacement of broken thermocouples. Cobra probes are standard tube-type pressure probes that may also contain thermocouples and that are routinely used in wind tunnels and aeronautical hardware. They are so named because in side views, they resemble a cobra poised to attack. Heretofore, there has been no easy way to replace a broken thermocouple in a cobra probe: instead, it has been necessary to break the probe apart and then rebuild it, typically at a cost between $2,000 and $4,000 (2004 prices). The modified design makes it possible to replace the thermocouple, in minimal time and at relatively low cost, by inserting new thermocouple wire in a tube.

  17. Endogenous Quality Effects of Trade Policy

    NARCIS (Netherlands)

    J.L. Moraga-Gonzalez (José Luis); J.M.A. Viaene (Jean-Marie)

    1999-01-01

    textabstractWe study the optimal trade policy against a foreign oligopoly with endogenous quality. We show that, under the Most Favoured Nation (MFN) clause, a uniform tariff policy is always welfare improving over the free trade equilibrium. However, a nonuniform tariff policy is always desirable

  18. Endogenous Quality Effects of Trade Policy

    NARCIS (Netherlands)

    J.L. Moraga-Gonzalez (José Luis); J.M.A. Viaene (Jean-Marie)

    1999-01-01

    textabstractWe study the optimal trade policy against a foreign oligopoly with endogenous quality. We show that, under the Most Favoured Nation (MFN) clause, a uniform tariff policy is always welfare improving over the free trade equilibrium. However, a nonuniform tariff policy is always desirable o

  19. An optimal policy for a single-vendor and a single-buyer integrated system with setup cost reduction and process-quality improvement

    Science.gov (United States)

    Shu, Hui; Zhou, Xideng

    2014-05-01

    The single-vendor single-buyer integrated production inventory system has been an object of study for a long time, but little is known about the effect of investing in reducing setup cost reduction and process-quality improvement for an integrated inventory system in which the products are sold with free minimal repair warranty. The purpose of this article is to minimise the integrated cost by optimising simultaneously the number of shipments and the shipment quantity, the setup cost, and the process quality. An efficient algorithm procedure is proposed for determining the optimal decision variables. A numerical example is presented to illustrate the results of the proposed models graphically. Sensitivity analysis of the model with respect to key parameters of the system is carried out. The paper shows that the proposed integrated model can result in significant savings in the integrated cost.

  20. Renal replacement therapy in ICU

    Directory of Open Access Journals (Sweden)

    C Deepa

    2012-01-01

    Full Text Available Diagnosing and managing critically ill patients with renal dysfunction is a part of the daily routine of an intensivist. Acute kidney insufficiency substantially contributes to the morbidity and mortality of critically ill patients. Renal replacement therapy (RRT not only does play a significant role in the treatment of patients with renal failure, acute as well as chronic, but also has spread its domains to the treatment of many other disease conditions such as myaesthenia gravis, septic shock and acute on chronic liver failure. This article briefly outlines the role of renal replacement therapy in ICU.

  1. Prioritization methodology for chemical replacement

    Science.gov (United States)

    Goldberg, Ben; Cruit, Wendy; Schutzenhofer, Scott

    1995-01-01

    This methodology serves to define a system for effective prioritization of efforts required to develop replacement technologies mandated by imposed and forecast legislation. The methodology used is a semi quantitative approach derived from quality function deployment techniques (QFD Matrix). QFD is a conceptual map that provides a method of transforming customer wants and needs into quantitative engineering terms. This methodology aims to weight the full environmental, cost, safety, reliability, and programmatic implications of replacement technology development to allow appropriate identification of viable candidates and programmatic alternatives.

  2. Wafer Replacement Cluster Tool (Presentation);

    Energy Technology Data Exchange (ETDEWEB)

    Branz, H. M.

    2008-04-01

    This presentation on wafer replacement cluster tool discusses: (1) Platform for advanced R and D toward SAI 2015 cost goal--crystal silicon PV at area costs closer to amorphous Si PV, it's 15% efficiency, inexpensive substrate, and moderate temperature processing (<800 C); (2) Why silicon?--industrial and knowledge base, abundant and environmentally benign, market acceptance, and good efficiency; and (3) Why replace wafers?--expensive, high embedded energy content, and uses 50-100 times more silicon than needed.

  3. Determining Optimal Machine Replacement Events with Periodic Inspection Intervals

    Science.gov (United States)

    2013-03-01

    contributed notable texts on the subject include Puterman [13] and Bertskas [2]. All these books offer their own unique approaches and merits, though...Methods for Reliability Data. Hoboken , NJ: John Wiley & Sons, 1998. [13] Puterman , Martin L. Markov Decision Processes. New York, NY: John Wiley and

  4. Corporate Accounting Policy Efficiency Improvement

    Directory of Open Access Journals (Sweden)

    Elena K. Vorobei

    2013-01-01

    Full Text Available The article is focused on the issues of efficient use of different methods of tax accounting for the optimization of income tax expenses and their consolidation in corporate accounting policy. The article makes reasoned conclusions, concerning optimal selection of depreciation methods for tax and bookkeeping accounting and their consolidation in corporate accounting policy and consolidation of optimal methods of cost recovery in production, considering business environment. The impact of the selected methods on corporate income tax rates and corporate property tax rates was traced and tax recovery was estimated.

  5. BABAR IFR Replacement R and D

    CERN Document Server

    Berry, M

    2003-01-01

    The Instrumented Flux Return (IFR) of the BaBar detector will soon need to be replaced by a more robust muon detection system. Scintillator bars with embedded Wavelength Shifting (WLS) fibers and Limited Streamer Tubes are two replacement technology options. The scintillator bars are tested for attenuation length; and causes for the large width of the Photo Multiplier Tube (PMT) signal are analyzed by Monte Carlo simulation. Cooling techniques for Avalanche Photo Diodes (APD) are investigated. The fairly high attenuation length coupled with the narrow PMT signal make the scintillator a viable option for a muon detecting system. Continuing work will focus on increasing timing resolution using an APD to read the signal from the WLS fibers, and investigating the lifetime of the APD. The ability to read a signal from the LST on external copper strips is tested and signals are found to be clearly distinguishable from noise. The voltage is compared to count rate to find that the optimal operating voltage for the LS...

  6. Replacing a battery by a nanogenerator with 20 V output

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Youfan; Lin, Long; Zhang, Yan; Wang, Zhong Lin [School of Material Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia (United States)

    2012-01-03

    Replacing batteries by nanogenerators (NGs) in small consumer electronics is one of the goals in the emerging field of self-powered nanotechnology. We show that the maximum measured output voltage of an NG optimized with pretreatments on the as-grown ZnO nanowire films reaches 20 V and the output current exceeds 6 {mu}A, which corresponds to a power density of 0.2 W cm{sup -3}. The NG is also demonstrated to replace a battery for driving a electronic watch. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. An asymptotic optimality result for the multiclass queue with finite buffers in heavy traffic

    Directory of Open Access Journals (Sweden)

    Rami Atar

    2015-03-01

    Full Text Available For a multiclass G/G/1 queue with finite buffers, admission and scheduling control, and holding and rejection costs, we construct a policy that is asymptotically optimal in the heavy traffic limit. The policy is specified in terms of a single parameter which constitutes the free boundary point from the Harrison-Taksar free boundary problem, but otherwise depends explicitly on the problem data. The cμ priority rule is also used by the policy, but in a way that is novel, and, in particular, different than that used in problems with infinite buffers. We also address an analogous problem where buffer constraints are replaced by throughput time constraints.

  8. Double emulsions as fat replacers

    NARCIS (Netherlands)

    Oppermann, Anika

    2017-01-01

    The use of double (w1/o/w2) emulsions, in which part of the oil is replaced by small water droplets, is a promising strategy to reduce oil content in food products. For successful applications, (1) significant levels of fat reduction (i.e. significant amounts of water inside the oil droplets) have

  9. The Revised European Neighbourhood Policy: Continuity and Change in EU Foreign Policy

    NARCIS (Netherlands)

    Bouris, D.; Schumacher, T.

    2017-01-01

    This book analyses the revised European Neighbourhood Policy (ENP) which entered into force in May 2011, thereby replacing its predecessor of 2003/2004. The edited volume provides a structured and comprehensive overview of the most recent developments in EU foreign policy (EUFP) towards the EU’s sou

  10. 考虑即时采购价格的物流服务供应链优化%Optimal Policies of Logistics Service Supply Chain with Instant Procurement Price

    Institute of Scientific and Technical Information of China (English)

    王志宏; 邵奇明; 王晓锋

    2016-01-01

    Uncertainty of logistics service market would influence logistics service level and profits of logistics service supply chain( LSSC) .In the case of considering stochastic instant procurement price and the differences between normal investment cost and emergency investment cost of basic logistics service provider( BLSP) , option mechanism is introduced to study the optimization decisions of LSSC under uncertain market environment in order to improve the supply chain flexibility and to decrease the risks caused by market uncertainty.The mathematical option contact models of BLSP and logistics service integrator( LSI) are built.Stackelberg game theory and opti-mization methods are employed to analyze and obtain LSI’ s optimal procurement decisions of option ordering and instant ordering as well as BLSP’ s logistics capability investment policy.The results show that instant procure-ment price and emergency investment cost have effects on the policies of LSI and BLSP.Finally, the influences of the variability of instant purchase price on optimal logistics capability investment value of BLSP and optimal option quantity of LSI and profits of both are examined by numerical analyses.%物流服务市场的不确定性会影响物流服务供应链的服务水平和收益。在考虑随机即时采购价格以及基础物流提供商在正常情况和应急情况下具有不同物流能力投资成本的情形下,引入期权机制研究不确定市场环境下物流服务供应链的优化决策,以提高物流服务供应链柔性和降低市场不确定性带来的风险。构建物流服务供应链的期权契约模型,采用Stackelberg博弈理论和优化算法分析和求得物流服务集成商的最优期权采购和即时采购策略,以及基础物流提供商的最优物流能力投资策略。结果表明即时采购价格将影响基础物流提供商和物流服务集成商的决策。最后通过数值分析研究即时采购价格的不确定

  11. 脂代果蔬/鹿肉复合发酵香肠加工特性与工艺优化%Fermented Venison Sausages with Added Fruits and Vegetables Made by Replacement of Pork Fat with Vegetable Oils:Processing Properties and Process Optimization

    Institute of Scientific and Technical Information of China (English)

    姚光明; 张猛; 刘佳彤; 周亚军; 马龙彪

    2014-01-01

    This paper reports the production of fermented venison sausages with added fruits and vegetables by partial replacement of pork fat with emulsified vegetable oils, which have improved nutritional and health benefits. The processing properties were investigated and the process conditions were optimized. In order to find optimal conditions for fat substitution, we performed a comparative evaluation of the sensory properties and iodine value of fermented sausages with partial replacement of pork fat by different kinds of emulsified vegetable oils in different proportions. The effects of fermentation temperature, time and inoculum amount on the pH, iodine value and protein degradation of fermented sausages were examined by single factor method. Based on iodine value, the optimal levels for the three variables as well as fat substitution were determined by central composite design as 28℃,23.7 h, 0.94% and 70%, respectively. By correlation analysis, linear regression models were developed indicating moisture content and water holding capacity as a function of texture properties, respectively.%制备具有营养保健功能的脂代果蔬/鹿肉复合发酵香肠,以乳化植物油取代原料中常用的动物脂肪,研究其加工特性与工艺优化。利用不同种类乳化植物油,对果蔬/鹿肉复合发酵香肠中的猪肉脂肪进行不同比例的取代,通过比较感官特性和碘值,得到植物油脂取代的最佳比例;通过发酵工艺单因素试验,研究发酵温度、发酵时间和菌种用量对脂代果蔬/鹿肉复合发酵香肠pH值、碘值和蛋白质的影响;利用中心复合试验设计,以碘值为评价指标,优化出脂代果蔬/鹿肉复合发酵香肠最佳发酵工艺参数为油脂取代量70%、发酵温度28℃、发酵时间23.7 h、菌种用量0.94%;通过脂代发酵香肠水分含量与质构特性的相关性研究,建立了水分含量和持水性的线性回归模型。

  12. Bonding over Dentin Replacement Materials.

    Science.gov (United States)

    Meraji, Naghmeh; Camilleri, Josette

    2017-08-01

    Dentin replacement materials are necessary in large cavities to protect the pulp and reduce the bulk of filling material. These materials are layered with a composite resin restorative material. Microleakage caused by poor bonding of composite resin to underlying dentin replacement material will result in pulp damage. The aim of this study was to characterize the interface between dentin replacement materials and composite resin and to measure the shear bond strength after dynamic aging. Biodentine (Septodont, Saint Maur-des-Fosses, France), Theracal LC (Bisco, Schaumburg, IL), and Fuji IX (GC, Tokyo, Japan) were used as dentin replacement materials. They were then overlaid with a total-etch and bonding agent or a self-etch primer and composite resin or a glass ionomer cement. All combinations were thermocycled for 3000 cycles. The interface was characterized using scanning electron microscopy and elemental mapping. Furthermore, the shear bond strength was assessed. The Biodentine surface was modified by etching. The Theracal LC and Fuji IX microstructure was unchanged upon the application of acid etch. The Biodentine and glass ionomer interface showed an evident wide open space, and glass particles from the glass ionomer adhered to the Biodentine surface. Elemental migration was shown with aluminum, barium, fluorine, and ytterbium present in Biodentine from the overlying composite resin. Calcium was more stable. The bond strength between Theracal LC and composite using a total-etch technique followed by self-etch primer achieved the best bond strength values. Biodentine exhibited the weakest bond with complete failure of bonding shown after demolding and thermocycling. Dynamic aging is necessary to have clinically valid data. Bonding composite resin to water-based dentin replacement materials is still challenging, and further alternatives for restoration of teeth using such materials need to be developed. Copyright © 2017 American Association of Endodontists

  13. Maintenance Policy for Multi-Component System with Fuzzy Lifetimes

    Institute of Scientific and Technical Information of China (English)

    赵瑞清; 高金伍

    2003-01-01

    The application of possibility theory to maintenance policies is proposed in this paper. The lifetime of a component is modeled as a fuzzy variable. Two types of replacement policies-block replacement and age replacement with fuzzy lifetimes are investigated. The theorems show that the long-run average fuzzy reward per unit time in both policies is just the expected cost per unit of time. In order to solve the proposed models, a hybrid intelligent algorithm is employed. Finally, numerical examples are provided for the sake of illustration.

  14. Best practices and recommendations on policy packaging

    OpenAIRE

    Fearnley, Nils; Longva, Frode; Ramjerdi, Farideh; Kessler, Florian; Osland, Oddgeir; Justen, Andreas; Gudmundsson, Henrik; Sørensen, Claus Hedegaard; Schippl, Jens; Åkerman, Jonas; Isaksson, Karolina; Givoni, Moshe; Macmillan, James; Vesela, Jirina; Vencl, Vaclav

    2011-01-01

    This report, which is the final deliverable of the Optic project (Optimal Policies for Transport In Combination), summarises two years of collaborative research into the policy process of combining individual measures into policy packages. Six stages of the policy process are identified. This report gives practical and general advice for each of these stages: 1. Define objectives and targets 2. Create an inventory of measures, identify potential primary measures and detect causal relationship...

  15. Agent-Based Optimization

    CERN Document Server

    Jędrzejowicz, Piotr; Kacprzyk, Janusz

    2013-01-01

    This volume presents a collection of original research works by leading specialists focusing on novel and promising approaches in which the multi-agent system paradigm is used to support, enhance or replace traditional approaches to solving difficult optimization problems. The editors have invited several well-known specialists to present their solutions, tools, and models falling under the common denominator of the agent-based optimization. The book consists of eight chapters covering examples of application of the multi-agent paradigm and respective customized tools to solve  difficult optimization problems arising in different areas such as machine learning, scheduling, transportation and, more generally, distributed and cooperative problem solving.

  16. Policy Capacity Is Necessary but Not Sufficient; Comment on “Health Reform Requires Policy Capacity”

    Directory of Open Access Journals (Sweden)

    Sheldon Gen

    2015-12-01

    Full Text Available Policy capacity focuses on the managerial and organizational abilities to inform policy decisions with sound research and analysis, and facilitate policy implementation with operational efficiency. It stems from a view of the policy process that is rational and positivistic, in which optimal policy choices can be identified, selected, and implemented with objectivity. By itself, however, policy capacity neglects the political aspects of policy-making that can dominate the process, even in health policies. These technical capabilities are certainly needed to advance reforms in health policies, but they are not sufficient. Instead, they must be complemented with public engagement and policy advocacy to ensure support from the public that policies are meant to serve.

  17. Salto Talaris fixed-bearing total ankle replacement system.

    Science.gov (United States)

    Rush, Shannon M; Todd, Nicholas

    2013-01-01

    The Salto Talaris total ankle replacement is an anatomically designed fixed bearing prosthesis available in the United States based on the successful design of the mobile-bearing Salto prosthesis available outside the United States. The original mobile-bearing design was modified and the mobile-bearing was transferred to the precision instrumentation at the trial phase evaluation. Instrumentation and technique allow the surgeon to determine the functional joint axis before final implantation. The Salto Talaris total ankle replacement design blends minimal bone resection and optimizes surface area, cortical contact, and ultra-high molecular weight polyethylene conformity. The authors present an overview of the Salto Talaris total ankle replacement surgical technique and pearls for successful application.

  18. Urbanization, Ikization, and Replacement Dynamics

    CERN Document Server

    Chen, Yanguang

    2015-01-01

    The phenomenon of Iks was first found by anthropologists and biologists, but it is actually a problem of human geography. However, it has not yet drawn extensive attention of geographers. In this paper, a hypothesis of ikization is presented that sudden and violent change of geographical environments results in dismantling of traditional culture, which then result in collective depravity of a nationality. By quantitative analysis and mathematical modeling, the causality between urbanization and ikization is discussed, and the theory of replacement dynamics is employed to interpret the process of ikization. Urbanization is in essence a nonlinear process of population replacement. Urbanization may result in ikization because that the migration of population from rural regions to urban regions always give rise to abrupt changes of geographical environments and traditional culture. It is necessary to protect the geographical environment against disruption, and to inherit and develop traditional culture in order t...

  19. [MINIMALLY INVASIVE AORTIC VALVE REPLACEMENT].

    Science.gov (United States)

    Tabata, Minoru

    2016-03-01

    Minimally invasive aortic valve replacement (MIAVR) is defined as aortic valve replacement avoiding full sternotomy. Common approaches include a partial sternotomy right thoracotomy, and a parasternal approach. MIAVR has been shown to have advantages over conventional AVR such as shorter length of stay and smaller amount of blood transfusion and better cosmesis. However, it is also known to have disadvantages such as longer cardiopulmonary bypass and aortic cross-clamp times and potential complications related to peripheral cannulation. Appropriate patient selection is very important. Since the procedure is more complex than conventional AVR, more intensive teamwork in the operating room is essential. Additionally, a team approach during postoperative management is critical to maximize the benefits of MIAVR.

  20. Policy Innovation in Innovation Policy

    DEFF Research Database (Denmark)

    Borras, Susana

    as with national and sub-national governments in Europe, all of them introducing interesting novelties in their innovation policy. These changes refer to different aspects of policy, mainly the content of policy initiatives towards science, technology and innovation; the instruments governments are using...... to achieve their goals; and the actors in the policy system that are being mobilised in pursuing these goals. This paper deals with these policy changes, paying special attention to the novelties introduced since the early 1990s in Europe. The perspective of this paper deals mainly on the changes introduced...... at the EU level, and mentions similar trends taking place at national and sub-national levels. The questions that guide the contents here are essentially three, namely, what are the main traits of innovation policies in Europe since the 1990s and how have the EU and different national governments approached...

  1. Mitochondrial Replacement: Ethics And Identity

    OpenAIRE

    Wrigley, Anthony; Wilkinson, Stephen; Appleby, John B

    2015-01-01

    Mitochondrial replacement techniques (MRTs) have the potential to allow prospective parents who are at risk of passing on debilitating or even life-threatening mitochondrial disorders to have healthy children to whom they are genetically related. Ethical concerns have however been raised about these techniques. This article focuses on one aspect of the ethical debate, the question of whether there is any moral difference between the two types of MRT proposed: Pronuclear Transfer (PNT) and Mat...

  2. 一种新的基于不完全排错的最优软件发行策略%A Novel Optimal Software Release Policy under Imperfect Debugging

    Institute of Scientific and Technical Information of China (English)

    刘云; 田斌; 赵玮

    2005-01-01

    Optimal software releasing is a challenging problem in software reliability. Most of the available software release models have an unreasonable assumption that the software debugging process is perfect or there is no new fault introduced during debugging. This paper presents an optimal software release policy model under imperfect debugging. This model not only takes the software imperfect debugging and the new faults introduced during debugging into account, but also considers the situation that the probability of perfect debugging will be increased while the experience is gained during the process of software testing. This paper also gives the solution of the model.%软件的最优发行管理问题是软件可靠性研究的一个关键问题.现有的最优软件发行模型大都假定软件排错过程是完全的,并且在排错过程中没有新的故障引入,这种假设在很多情况下是不合理的.本文提出了一种新的最优软件发行管理模型,该模型既考虑了软件的不完全排错过程,又考虑了在排错过程中可能会引入新的故障,同时还考虑了由于排错经验的不断积累,软件的完全排错概率会增加的情况.本文同时给出了该模型的解.

  3. Replacing magnets at the LHC

    CERN Multimedia

    LHC, LSI2, Point 4

    2013-01-01

    CERN engineers have been working through the night this week to move the final replacement dipole magnets into position on the Large Hadron Collider (LHC). Though there are several still to go, the teams expect to have completed the task by the end of this month. Dipole magnets bend the paths of particles as they travel around the circular accelerator. Of the LHC's 1232 dipoles – each 15 metres long and weighing 35 tonnes – 15 are being replaced as part of the long shutdown of CERN's accelerator complex. These 15 magnets suffered wear and tear during the LHC's first 4-year run. Three quadrupole-magnet assemblies – which help to focus particles into a tight beam – have also been replaced. Moving such heavy magnets requires specially adapted cranes and trailers both above and below ground. There are several access points on the LHC. Some, such as the 100-metre vertical access shaft down to the ALICE experiment, are equipped with lifts to allow technical personnel and visitors down to the caverns. Other ...

  4. Results of Austin Moore replacement.

    Directory of Open Access Journals (Sweden)

    Jadhav A

    1996-04-01

    Full Text Available Forty cases of Austin Moore Replacement done for transcervical fractures of the femur in patients were reviewed after a period of 12 to 48 months postoperatively (mean 26 mth. 30 cases (75% had mild to severe pain of non-infective origin, starting as early as 6 months postoperatively. This was irrespective of the make, size or position (varus/valgus of the prosthesis. Though the Aufranc and Sweet clinical scoring was satisfactory in 65% cases, radiological evidence of complications like sinking, protrusion, etc. were seen in majority of the cases. Calcar resorption was seen in 34 cases (85% as early as 4 months postoperatively. Results of THR and bipolar replacement done for transcervical fractures in recent literature show 85% pain-free cases at 5 years. We feel that Austin Moore Replacement should be reserved for patients more than 65 years of age and those who are less active or debilitated because of other factors, because of increased acetabular wear with time in the younger individual. This is corroborated by unsatisfactory results in patients less than 65 years of age (p < 0.05.

  5. The caudal septum replacement graft.

    Science.gov (United States)

    Foda, Hossam M T

    2008-01-01

    To describe a technique for reconstructing the lost tip support in cases involving caudal septal and premaxillary deficiencies. The study included 120 patients with aesthetic and functional nasal problems resulting from the loss of caudal septal and premaxillary support. An external rhinoplasty approach was performed to reconstruct the lost support using a cartilaginous caudal septum replacement graft and premaxillary augmentation with Mersilene mesh. The majority of cases (75%) involved revisions in patients who had previously undergone 1 or more nasal surgical procedures. A caudal septum replacement graft was combined with premaxillary augmentation in 93 patients (77.5%). The mean follow-up period was 3 years (range, 1-12 years). The technique succeeded in correcting the external nasal deformities in all patients and resulted in a significant improvement in breathing in 74 patients (86%) with preoperative nasal obstruction. There were no cases of infection, displacement, or extrusion. The caudal septum replacement graft proved to be very effective in restoring the lost tip support in patients with caudal septal deficiency. Combining the graft with premaxillary augmentation using Mersilene mesh helped increase support and stability over long-term follow-up.

  6. QUALITY OF LIFE PARAMETERS IMPROVEMENT FOLLOWING TOTAL HIP REPLACEMENT

    OpenAIRE

    Grierosu, Carmen

    2012-01-01

    Large joint replacement regarding lower limbs include hip and knee arthroplasty surgical procedures, meant toimprove Quality Of Life (QOL) parameters, an optimal representation for patient recovery toward an independent lifestyle. The present study is a consequence of an imperative requirement from the nursing staff, which, in closecooperation with the surgeon, the physical therapist and the psychologist intend a better understanding regardingpatient perception of the so-called post-discharge...

  7. Inventory-transportation integrated optimization for maintenance spare parts of high-speed trains.

    Science.gov (United States)

    Lin, Boliang; Wang, Jiaxi; Wang, Huasheng; Wang, Zhongkai; Li, Jian; Lin, Ruixi; Xiao, Jie; Wu, Jianping

    2017-01-01

    This paper presents a 0-1 programming model aimed at obtaining the optimal inventory policy and transportation mode for maintenance spare parts of high-speed trains. To obtain the model parameters for occasionally-replaced spare parts, a demand estimation method based on the maintenance strategies of China's high-speed railway system is proposed. In addition, we analyse the shortage time using PERT, and then calculate the unit time shortage cost from the viewpoint of train operation revenue. Finally, a real-world case study from Shanghai Depot is conducted to demonstrate our method. Computational results offer an effective and efficient decision support for inventory managers.

  8. Optimally Stopped Optimization

    Science.gov (United States)

    Vinci, Walter; Lidar, Daniel A.

    2016-11-01

    We combine the fields of heuristic optimization and optimal stopping. We propose a strategy for benchmarking randomized optimization algorithms that minimizes the expected total cost for obtaining a good solution with an optimal number of calls to the solver. To do so, rather than letting the objective function alone define a cost to be minimized, we introduce a further cost-per-call of the algorithm. We show that this problem can be formulated using optimal stopping theory. The expected cost is a flexible figure of merit for benchmarking probabilistic solvers that can be computed when the optimal solution is not known and that avoids the biases and arbitrariness that affect other measures. The optimal stopping formulation of benchmarking directly leads to a real-time optimal-utilization strategy for probabilistic optimizers with practical impact. We apply our formulation to benchmark simulated annealing on a class of maximum-2-satisfiability (MAX2SAT) problems. We also compare the performance of a D-Wave 2X quantum annealer to the Hamze-Freitas-Selby (HFS) solver, a specialized classical heuristic algorithm designed for low-tree-width graphs. On a set of frustrated-loop instances with planted solutions defined on up to N =1098 variables, the D-Wave device is 2 orders of magnitude faster than the HFS solver, and, modulo known caveats related to suboptimal annealing times, exhibits identical scaling with problem size.

  9. Optimization and Optimal Control

    CERN Document Server

    Chinchuluun, Altannar; Enkhbat, Rentsen; Tseveendorj, Ider

    2010-01-01

    During the last four decades there has been a remarkable development in optimization and optimal control. Due to its wide variety of applications, many scientists and researchers have paid attention to fields of optimization and optimal control. A huge number of new theoretical, algorithmic, and computational results have been observed in the last few years. This book gives the latest advances, and due to the rapid development of these fields, there are no other recent publications on the same topics. Key features: Provides a collection of selected contributions giving a state-of-the-art accou

  10. Fusion following failed total ankle replacement.

    Science.gov (United States)

    Wünschel, Markus; Leichtle, Ulf G; Leichtle, Carmen I; Walter, Christian; Mittag, Falk; Arlt, Eva; Suckel, Andreas

    2013-04-01

    Although mid- to long-term results after total ankle replacement have improved because of available second- and third-generation devices, failure of total ankle replacement is still more common compared with total hip replacement and total knee replacement. The portfolio of available total ankle replacement revision component options is small. Furthermore, the bone stock of the tibiotalar region is scarce making it difficult and in some situations impossible to perform revision total ankle replacement. In these cases tibiotalar and tibiotalocalcaneal fusions are valuable options. This article describes which surgical procedures should be performed depending on the initial situation and gives detailed advice on surgical technique, postoperative care, and clinical results.

  11. Monetary policy as equilibrium selection

    OpenAIRE

    Gaetano Antinolfi; Costas Azariadis; Bullard, James B.

    2007-01-01

    Can monetary policy guide expectations toward desirable outcomes when equilibrium and welfare are sensitive to alternative, commonly held rational beliefs? This paper studies this question in an exchange economy with endogenous debt limits in which dynamic complementarities between dated debt limits support two Pareto-ranked steady states: a suboptimal, locally stable autarkic state and a constrained optimal, locally unstable trading state. The authors identify feedback policies that reverse ...

  12. Bullwhip reduction for ARMA demand : The proportional order-up-to policy versus the full-state-feedback policy

    NARCIS (Netherlands)

    Gaalman, G.J.C.

    2006-01-01

    A 'proportional' order-up-to policy reacting to ARMA demand is analyzed using stochastic optimal control theory. This policy is compared with a full-state-feedback order-up-to policy. Necessary conditions for an optimum of a weighted sum of the inventory and the ordering variances for both policies

  13. Bullwhip reduction for ARMA demand : The proportional order-up-to policy versus the full-state-feedback policy

    NARCIS (Netherlands)

    Gaalman, G.J.C.

    A 'proportional' order-up-to policy reacting to ARMA demand is analyzed using stochastic optimal control theory. This policy is compared with a full-state-feedback order-up-to policy. Necessary conditions for an optimum of a weighted sum of the inventory and the ordering variances for both policies

  14. Data Policy

    Directory of Open Access Journals (Sweden)

    Mark A Parsons

    2013-07-01

    Full Text Available The first purpose of data policy should be to serve the objectives of the organization or project sponsoring the collection of the data. With research data, data policy should also serve the broader goals of advancing scientific and scholarly inquiry and society at large. This is especially true with government-funded data, which likely comprise the vast majority of research data. Data policy should address multiple issues, depending on the nature and objectives of the data. These issues include data access requirements, data preservation and stewardship requirements, standards and compliance mechanisms, data security issues, privacy and ethical concerns, and potentially even specific collection protocols and defined data flows. The specifics of different policies can vary dramatically, but all data policies need to address data access and preservation. Research data gain value with use and must therefore be accessible and preserved for future access. This article focuses on data access. While policy might address multiple issues, at a first level it must address where the data stand on what Lyon (2009 calls the continuum of openness. Making data as openly accessible as possible provides the greatest societal benefit, and a central purpose of data policy is to work toward ethically open data access. An open data regime not only maximizes the benefit of the data, it also simplifies most of the other issues around effective research data stewardship and infrastructure development.

  15. Policy stories

    DEFF Research Database (Denmark)

    Ren, Carina Bregnholm; Rasmussen, Rasmus Kjærgaard

    planning and execution and of event outcomes beyond the narrow confines of bed nights and legacies. Second, we introduce policies as an entry point to unlock discussions and manifestations of value and futures which connect to AWG. In order to exemplify the workings of the AWG event in these domains, we...... present three central policy stories from the field. The stories tell of how the event was first interested, then activated and finally evaluated. Besides adding a new understanding to policy-driven events as a locus of value creation, we also argue that the AWG 2016 offer speculative bets for new...

  16. Radiology of total hip replacement

    Energy Technology Data Exchange (ETDEWEB)

    Griffiths, H.J.; Lovelock, J.E.; McCollister Evarts, C.; Geyer, D.

    1984-06-01

    The radiology of total hip replacement (THR) and its complications is reviewed in conjunction with a long-term follow-up study on 402 patients with 501 prostheses. The indications, contraindications, biomechanics, and operative management of these patients is discussed. Clinical complications such as deep vein thrombosis, pulmonary embolism, and hemorrhage are mentioned. Postoperative infections including granulomatous pseudotumors, dislocations and fractures, true loosening of the prosthesis, and heterotopic bone formation (HBF) are discussed and illustrated. The importance of differentiating the lucent line from true loosening is stressed. Mechanical and other clinical complications which are largely ignored by radiologists are also discussed. The uses of arthrography and bone scanning are included.

  17. [Proximal and total femur replacement].

    Science.gov (United States)

    Pennekamp, P H; Wirtz, D C; Dürr, H R

    2012-07-01

    Reconstruction of segmental bone defects of the proximal femur following wide tumor resection or revision arthroplasty. Aggressive benign or primary malignant bone tumors of the proximal femur; destructive metastases; massive segmental bone defects of the proximal femur; periprosthetic fractures. Local infection; very short life expectancy (acetabular bone stock. Anterolateral approach. Exposure and detachment of the iliopsoas and gluteus medius muscle from the proximal femur with a sufficient safety margin to the bone; distal transsection of the vastus lateralis/intermedius and rectus femoris muscle according to the extraosseous tumor extension; distal femur osteotomy al least 3 cm beyond the farthest point of tumor extension; in case of total femur replacement, additional lateral arthrotomy of the knee with resection of the ligaments and menisci; reaming of the medullary canal after securing the shaft with a Verbrugge clamp; trial assembly and reduction followed by the definitive implantation of the prosthesis with adjustment of the femoral neck anteversion in 5° increments; soft tissue reconstruction and fixation to an attachment tube covering the prosthesis; in case of total femur replacement, the preparation of the tibia is followed by the coupling of the tibial and femoral components. Infection prophylaxis, 20 kg partial weight bearing, continuous passive motion. A total of 20  patients with proximal femur replacement and 2 patients with total femur replacement implanted between June 2007 and December 2011 were retrospectively reviewed. Three patients had primary malignant bone tumors, while 19 patients underwent resection for metastatic disease. The mean age at surgery was 62.0 ± 18.1 years (18-82 years). Fifteen patients with a mean follow-up of 20.3 ± 17.2 months (4-51 months) were studied. Among the 22 cases, periprosthetic infection occurred in 3 patients (13.6%), dislocation in 2 patients (9.1%). Evaluation of the functional

  18. B Plant process piping replacement feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Howden, G.F.

    1996-02-07

    Reports on the feasibility of replacing existing embedded process piping with new more corrosion resistant piping between cells and between cells and a hot pipe trench of a Hanford Site style canyon facility. Provides concepts for replacement piping installation, and use of robotics to replace the use of the canyon crane as the primary means of performing/supporting facility modifications (eg, cell lining, pipe replacement, equipment reinstallation) and operational maintenenace.

  19. REMINDER REPLACEMENT OF FRENCH CARDS

    CERN Multimedia

    Human Resources Division; Cards.Service@cern.ch

    2001-01-01

    The French Ministry of Foreign Affairs is currently replacing all diplomatic cards, special cards and employment permits («attestations de fonctions») held by members of the personnel and their families. These cards are replaced by secure, computerized equivalents. The old cards may no longer be used after 31 December 2001. For the purposes of the handover, members of the personnel must go personally to the cards office (33/1-015) between 8h30 and 12h30, in order to fill in a «fiche individuelle» form, taking the following documents for themselves and members of their families already in possession of a French card : A recent identity photograph in 4.5 cm x 3.5 cm format, the French card in their possession, an A4 photocopy of the same French card, certified by the cards office as being a true copy. Those members of the personnel whose cards (and/or cards belonging to members of their families) are shortly due to expire, or have recently done so, are also requested...

  20. Total hip replacement in dancers.

    Science.gov (United States)

    Buyls, Inge R A E; Rietveld, A B M Boni; Ourila, Tiia; Emerton, Mark E; Bird, H A

    2013-04-01

    A case report of a professional contemporary dancer who successfully returned to the stage after bilateral total hip replacements (THR) for osteoarthritis is presented, together with her own commentary and a retrospective cohort study of total hip replacements in dancers. In the presented cohort, there were no post-operative dislocations or infections, the original pain had been relieved, rehabilitation was objectively normal and all resumed their dance (teaching) activities. Nevertheless, they were disappointed about the prolonged rehabilitation. Due to their high demands as professional dancers, post-operative expectations were too optimistic in view of the usual quick and favourable results of THR in the older and less physically active, general population. In all dancers with unilateral osteoarthritis, the left hip was involved, which may reflect the tendency to use the left leg as standing leg and be suggestive that strenuous physical activity may lead to osteoarthritis. Better rehabilitation guidelines are needed for dancer patients undergoing THR, especially drawing their attention to realistic post-operative expectations.

  1. 优化北京市文化创意产业投资环境的财税政策研究%Research on Tax Policy of Optimizing Investment Environment for Beijing Cultural and Creative Industry

    Institute of Scientific and Technical Information of China (English)

    丁芸

    2015-01-01

    The investment environment is very important to cultural and creative industry. Beijing,as the capital of China,must not only conform to the needs of the people in terms of the investment environment of cultural and creative industry,but also reflect the u-nique advantage of cultural heritage and the support of the government. However,compared with the developed countries,the develop-ment of Beijing cultural and creative industry still lacks in vitality. Multi-angle policy support is therefore necessary for the optimiza-tion of the investment environment of Beijing cultural and creative industry. Financially,special funds can be set up and used for cul-tural development,financial funds can be utilized to activate and amplify private investment,and government procurement system can be developed for cultural and creative products and services. Fiscally,the tax incentives of the cultural creative industry can be adopt-ed,together with the further improvement of the tax policy so as to support the "bringing in" and "going global" of the cultural and creative industries.%投资环境对文化创意产业至关重要。北京作为首都,在文化创意产业投资环境方面既要符合人民需求,又要体现文化底蕴和政府支持等独特优势。然而与发达国家相比,北京市文化创意产业的发展还欠缺活力。优化北京文化创意产业投资环境需要从多角度给予政策支持。从财政上,可以科学设置和使用文化发展专项资金、发挥财政资金对民间投资的拉动放大作用、积极拓展政府文化创意产品和服务的采购制度;从税收上,不仅可以从丰富文化创意产业的税收激励方式入手,还需要进一步完善税收政策以支持文化创意产业的“引进来”和“走出去”。

  2. The optimal monetary policy rule based on the unemployment rate and the inflation rate%基于失业率与通货膨胀率的我国最优货币政策规则选择

    Institute of Scientific and Technical Information of China (English)

    金成晓; 卢颖超

    2015-01-01

    In this paper,we build a small macroeconomic model with microeconomic foundation and dual sticky property to characterize the relationship between inflation rate and unemployment rate and gives the optimal monetary policy rules under the policy objectives.The results show that:(1 )The parameter of price sticky is 0.4936,there are 50.64% of companies which will follow the best way to adjust price in every quarter,and t,so assumes the existence of labor market friction reasonable;(2)Using inflation and unemployment rate as the threshold of the Interest rate has a smaller welfare loss;(3)When two variables are in a reasonable range,through loss the unemployment rate to exchange the stable of the inflation rate can get greater social welfare;(4)Lower wage sticky and moderately improve price sticky benefit the stable of economy.The innovations of this paper are that:We join the character of the labor market frictions in the New Keynesian model.%参考双粘性小型宏观经济模型刻画了通货膨胀率与失业率之间的动态关系,在此基础上给出了中国的最优货币政策规则形式。研究得出:(1)粘性价格系数为0.4936,每季度50.64%的企业会按照最优的方式来调整价格,粘性工资系数为0.5064,工资调整较慢,假定劳动力市场存在摩擦比较合理;(2)同时将通货膨胀预期及失业率作为阈值的利率规则具有更小的福利损失;(3)在两变量都处于合理区间时,通过损失失业率来换取通货膨胀的稳定可以使经济获得更大的福利。(4)降低工资粘性及适度升高价格粘性有利于经济的稳定。

  3. Impact of Replacing Business Tax with Value -added Tax on Finance and Accounting of Enterprises%营改增对企业财务和会计的影响

    Institute of Scientific and Technical Information of China (English)

    孟繁颖

    2016-01-01

    营改增在经过上海等地试点后,2013年8月起已经在全国推行,企业在新税制改革中将面临新的机遇和挑战。以营改增的政策演变背景分析为切入点,从企业税负压力、财务管理和会计核算、财务报表和发票管理层面,深入分析营改增对企业财务和会计的影响,提出营改增下优化企业财务和会计管理的相应策略。%the policy of replacing business tax with value - added tax has been implemented throughout the whole country from August ,2013 after the pilot project is launched in Shanghai and oth‐er places ,and enterprises will confront new chance and challenges in the reform of new tax system .Tak‐ing the evolution background of the policy of replacing business tax with value -added tax as break‐through point ,this paper analyzes the impact of replacing business tax with value -added tax on finance and accounting of enterprises in depth from the aspects of corporate tax pressure ,financial management and accounting ,financial reporting and invoice management to propose the corresponding strategy for optimizing corporate financial reporting and accounting management under the policy of replacing busi‐ness tax with value -added tax .

  4. Optimal Marketing Policy in a Random Network

    CERN Document Server

    Amini, Hamed

    2008-01-01

    Viral marketing takes advantage of preexisting social networks among customers to achieve large changes in behavior. Models of influence spread have been studied in a number of domains, including the effect of 'word of mouth' in the promotion of new products or the diffusion of technologies. A social network can be represented by a graph where the nodes are individuals and the edges indicate a form of social relationship. The flow of influence through this network can be thought of as an increasing process of active nodes: as individuals become aware of new technologies, they have the potential to pass them on to their neighbors. The goal of marketing is to trigger a large cascade of adoptions. In this paper, we present and solve an analytical model where the individuals are connected according to a large sparse random graph. Borrowing ideas and techniques from Markov random fields, we derive analytical results for various threshold models. The parameters of the model (like the initial fraction of active indi...

  5. Optimal Dynamic Advertising Policy for New Products

    OpenAIRE

    Trichy V. Krishnan; Dipak C. Jain

    2006-01-01

    Advertising is one of the key marketing tools managers have at their disposal to influence their customers into purchasing a new product. The overall objective of new product advertising is to inform and persuade customers. Drawing up an advertising plan for a new product that is under the influence of diffusion phenomenon is not an easy task. Hence, research in this area is very limited. In our research, we use an empirically proven diffusion demand function that explicitly incorporates the ...

  6. Learning, Inflation Reduction and Optimal Monetary Policy

    NARCIS (Netherlands)

    Schaling, E.

    2003-01-01

    In this paper we analyze disinflation in two environments.One in which the central bank has perfect knowledge, in the sense that it understands and observes the process by which private sector inflation expectations are generated, and one in which the central bank has to learn the private sector

  7. 风险资本约束下保险公司的最优比例再保险-投资策略%Optimal proportional reinsurance-investment policies for an insurer under Capital-at-Risk constraint

    Institute of Scientific and Technical Information of China (English)

    曾燕; 李仲飞

    2011-01-01

    This paper investigates a reinsurance-investment problem for an insurer.Assume that the integral risk of the insurer is measured by Capital-at-Risk(CaR), the surplus process is described by a diffusion approximation model;the insurer is allowed to purchase proportional reinsurance(or acquire new business) and to invest on a risk-free asset and multiple risky assets at any time; the prices of risky assets are driven by the model of geometric Brownian motions.The target of the insurer is to maximize the expectation of the terminal wealth under a CaR constraint.Two mean-CaR models are established for the problem.Explicit expressions of the optimal policies and efficient frontiers to the models are derived by using a hierarchical optimization method and the variational calculus approach.%本文研究保险公司的再保险-投资问题.假定保险公司的整体风险由风险资本(Capital-at-Risk,CaR)来度量;盈余过程由扩散模型近似表示;在任意时刻保险公司可购买比例再保险(或获取新业务)和投资无风险资产与多种风险资产;风险资产的价格由几何布朗运动驱动.保险公司的目标是在整体风险CaR受约束的条件下最大化终端财富的期望值.对这一问题,建立了两个均值-CaR模型.利用分层优化方法和变分法,得到了模型的最优比例再保险一投资策略以及有效边界的解析表达式.

  8. Approximate Policy Iteration with a Policy Language Bias: Solving Relational Markov Decision Processes

    CERN Document Server

    Fern, A; Yoon, S; 10.1613/jair.1700

    2011-01-01

    We study an approach to policy selection for large relational Markov Decision Processes (MDPs). We consider a variant of approximate policy iteration (API) that replaces the usual value-function learning step with a learning step in policy space. This is advantageous in domains where good policies are easier to represent and learn than the corresponding value functions, which is often the case for the relational MDPs we are interested in. In order to apply API to such problems, we introduce a relational policy language and corresponding learner. In addition, we introduce a new bootstrapping routine for goal-based planning domains, based on random walks. Such bootstrapping is necessary for many large relational MDPs, where reward is extremely sparse, as API is ineffective in such domains when initialized with an uninformed policy. Our experiments show that the resulting system is able to find good policies for a number of classical planning domains and their stochastic variants by solving them as extremely lar...

  9. MDP Optimal Control under Temporal Logic Constraints

    CERN Document Server

    Ding, Xu Chu; Belta, Calin; Rus, Daniela

    2011-01-01

    In this paper, we develop a method to automatically generate a control policy for a dynamical system modeled as a Markov Decision Process (MDP). The control specification is given as a Linear Temporal Logic (LTL) formula over a set of propositions defined on the states of the MDP. We synthesize a control policy such that the MDP satisfies the given specification almost surely, if such a policy exists. In addition, we designate an "optimizing proposition" to be repeatedly satisfied, and we formulate a novel optimization criterion in terms of minimizing the expected cost in between satisfactions of this proposition. We propose a sufficient condition for a policy to be optimal, and develop a dynamic programming algorithm that synthesizes a policy that is optimal under some conditions, and sub-optimal otherwise. This problem is motivated by robotic applications requiring persistent tasks, such as environmental monitoring or data gathering, to be performed.

  10. ORO. The physical developer replacement?

    Science.gov (United States)

    Wood, Michael A; James, Tim

    2009-12-01

    In the process of fingerprint development Physical Developer has been largely the method of choice on porous surfaces after coming into contact with wet environments. It is only recently that a new technique has been identified which could replace this standard technique. This study aims to build on previous research and expand knowledge regarding the technique. The study built on previous research and compared Physical Developer to Oil Red O, testing both on four paper types, while being placed in three different water types and an accelerant for various amounts of time. Marks were placed with both heavily 'loaded' sebaceous fingers and 'normal' un-washed fingers. Results show that Oil Red O consistently produced clearer more detailed marks from the 'loaded' fingers, but neither technique proved to work better on the 'normal' marks. Neither technique developed any prints from the accelerant.

  11. Controversies in hormone replacement therapy

    Directory of Open Access Journals (Sweden)

    A. Baziad

    2001-09-01

    Full Text Available Deficiency of estrogen hormone will result in either long-term or short-term health problems which may reduce the quality of life. There are numerous methods by which the quality of female life can be achieved. Since the problems occuring are due to the deficiency of estrogen hormone, the appropriate method to tackle the problem is by administration of estrogen hormone. The administration of hormone replacement therapy (HRT with estrogen may eliminate climacteric complaints, prevent osteoporosis, coronary heart disease, dementia, and colon cancer. Although HRT has a great deal of advantage, its use is still low and may result in controversies. These controversies are due to fact that both doctor and patient still hold on to the old, outmoded views which are not supported by numerous studies. Currently, the use of HRT is not only based on experience, or temporary observation, but more on evidence based medicine. (Med J Indones 2001; 10: 182-6Keywords: controversies, HRT

  12. Replacement reactor to revolutionise magnets

    CERN Document Server

    Atkins, G

    2002-01-01

    Electric motors, hearing aids and magnetic resonance imaging are only some of the applications that will benefit from the first advances in magnets in a quarter of a century. Magnets achieve their characteristics when electrons align themselves to produce a unified magnetic field. Neutrons can probe these magnetic structures. The focus is not just on making more powerful magnets, but also identifying the characteristics that make magnets cheaper and easier for industry to manufacture. Staff from the ANSTO's Neutron Scattering Group have already performed a number of studies on the properties of magnets using using HIFAR, but the Replacement Research Reactor that will produce cold neutrons would allow scientists to investigate the atomic properties of materials with large molecules. A suite of equipment will enable studies at different temperatures, pressures and magnetic fields

  13. Renal replacement therapy in Europe

    DEFF Research Database (Denmark)

    Noordzij, Marlies; Kramer, Anneke; Abad Diez, José M

    2014-01-01

    BACKGROUND: This article provides a summary of the 2011 ERA-EDTA Registry Annual Report (available at www.era-edta-reg.org). METHODS: Data on renal replacement therapy (RRT) for end-stage renal disease (ESRD) from national and regional renal registries in 30 countries in Europe and bordering the .......6-47.0], and on dialysis 39.3% (95% CI 39.2-39.4). The unadjusted 5-year patient survival after the first renal transplantation performed between 2002 and 2006 was 86.7% (95% CI 86.2-87.2) for kidneys from deceased donors and 94.3% (95% CI 93.6-95.0) for kidneys from living donors....

  14. Filters in topology optimization

    DEFF Research Database (Denmark)

    Bourdin, Blaise

    1999-01-01

    In this article, a modified (``filtered'') version of the minimum compliance topology optimization problem is studied. The direct dependence of the material properties on its pointwise density is replaced by a regularization of the density field using a convolution operator. In this setting...... it is possible to establish the existence of solutions. Moreover, convergence of an approximation by means of finite elements can be obtained. This is illustrated through some numerical experiments. The ``filtering'' technique is also shown to cope with two important numerical problems in topology optimization...

  15. Filters in topology optimization

    DEFF Research Database (Denmark)

    Bourdin, Blaise

    1999-01-01

    In this article, a modified (``filtered'') version of the minimum compliance topology optimization problem is studied. The direct dependence of the material properties on its pointwise density is replaced by a regularization of the density field using a convolution operator. In this setting...... it is possible to establish the existence of solutions. Moreover, convergence of an approximation by means of finite elements can be obtained. This is illustrated through some numerical experiments. The ``filtering'' technique is also shown to cope with two important numerical problems in topology optimization...

  16. Leptin replacement improves cognitive development.

    Directory of Open Access Journals (Sweden)

    Gilberto J Paz-Filho

    Full Text Available BACKGROUND: Leptin changes brain structure, neuron excitability and synaptic plasticity. It also regulates the development and function of feeding circuits. However, the effects of leptin on neurocognitive development are unknown. OBJECTIVE: To evaluate the effect of leptin on neurocognitive development. METHODOLOGY: A 5-year-old boy with a nonconservative missense leptin gene mutation (Cys-to-Thr in codon 105 was treated with recombinant methionyl human leptin (r-metHuLeptin at physiologic replacement doses of 0.03 mg/kg/day. Cognitive development was assessed using the Differential Ability Scales (DAS, a measure of general verbal and nonverbal functioning; and selected subtests from the NEPSY, a measure of neuropsychological functioning in children. PRINCIPAL FINDINGS: Prior to treatment, the patient was morbidly obese, hypertensive, dyslipidemic, and hyperinsulinemic. Baseline neurocognitive tests revealed slower than expected rates of development (developmental age lower than chronological age in a majority of the areas assessed. After two years, substantial increases in the rates of development in most neurocognitive domains were apparent, with some skills at or exceeding expectations based on chronological age. We also observed marked weight loss and resolution of hypertension, dyslipidemia and hyperinsulinemia. CONCLUSIONS: We concluded that replacement with r-metHuLeptin is associated with weight loss and changes in rates of development in many neurocognitive domains, which lends support to the hypothesis that, in addition to its role in metabolism, leptin may have a cognitive enhancing role in the developing central nervous system. TRIAL REGISTRATION: ClinicalTrials.gov NCT00659828.

  17. The Theory of Optimal Taxation

    DEFF Research Database (Denmark)

    Sørensen, Peter Birch

    The theory of optimal taxation has often been criticized for being of little practical policy relevance, due to a lack of robust theoretical results. This paper argues that recent advances in optimal tax theory has made that theory easier to apply and may help to explain some current trends in in...

  18. [Renal replacement therapy for refractory heart failure].

    Science.gov (United States)

    Schwenger, V; Remppis, A B

    2012-07-01

    After broad cardiological and nephrological evaluation and consideration of optimal conservative options according to national and international guidelines, renal replacement therapy might be helpful in patients with refractory heart failure even if they are not dialysis-dependent. This is even more important as renal failure is a strong predictor for mortality in patients with severe congestive heart failure (CHF) and CHF is one of the fastest growing morbidities in western countries. Although peritoneal dialysis (PD) is frequently used in patients with CHF its role remains unclear. Acute chronic volume overload in refractory CHF is still an unresolved clinical problem. In patients with acute heart and renal failure with need of management in an intensive care unit, extracorporeal ultrafiltration or a dialysis modality should be preferred. In patients with chronic refractory CHF, volume overload and renal failure, peritoneal dialysis should be the therapy of choice. Due to the limited data available, treatment and outcome parameters should be recorded in the registry of the German Society of Nephrology (http://www.herz-niere.de).

  19. Optimal Control and Optimization of Stochastic Supply Chain Systems

    CERN Document Server

    Song, Dong-Ping

    2013-01-01

    Optimal Control and Optimization of Stochastic Supply Chain Systems examines its subject in the context of the presence of a variety of uncertainties. Numerous examples with intuitive illustrations and tables are provided, to demonstrate the structural characteristics of the optimal control policies in various stochastic supply chains and to show how to make use of these characteristics to construct easy-to-operate sub-optimal policies.                 In Part I, a general introduction to stochastic supply chain systems is provided. Analytical models for various stochastic supply chain systems are formulated and analysed in Part II. In Part III the structural knowledge of the optimal control policies obtained in Part II is utilized to construct easy-to-operate sub-optimal control policies for various stochastic supply chain systems accordingly. Finally, Part IV discusses the optimisation of threshold-type control policies and their robustness. A key feature of the book is its tying together of ...

  20. Perioperative analgesia in total knee replacement:multimodal analgesia schemes and optimal pain management%人工全膝关节置换围术期镇痛方法:多模式方案及最佳疼痛管理

    Institute of Scientific and Technical Information of China (English)

    孙扬; 杨明敏; 李亦梅

    2014-01-01

    , epidural analgesia, peripheral nerve block, joint local analgesia, patient control ed analgesia, cold treatment”in Chinese and English. RESULTS AND CONCLUSION:There were 986 articles after the initial survey. Final y, 55 articles were included according to the inclusion and exclusion criteria. As the technology for total knee arthroplasty, early functional rehabilitation and replacement of pain control has been widely concerned, a large number of literatures about analgesic drugs and analgesic programs emerge. Analgesic drugs include opioids, non-steroidal anti-inflammatory drugs, local anesthetics and N-methyl-aspartate receptor blockers. Analgesic program includes epidural analgesia, peripheral nerve blockage, joint local analgesia, patient-control ed analgesia and cold therapy. These analgesic drugs and methods have their advantages and disadvantages. At present, multimodal analgesia schemes have been recognized, but the optimal pain management scheme remains controversial. Increasing considerations should be paid on the choice of analgesic methods, depending on individual characteristics and existing technology.