Several researches have been done to provide better alternative to the existing replacement models, but the research works did not adequately address the replacement problem for items that fail suddenly. Hence, a modi...Several researches have been done to provide better alternative to the existing replacement models, but the research works did not adequately address the replacement problem for items that fail suddenly. Hence, a modified replacement model for items that fail suddenly has been proposed using the knowledge of probability distribution of failure times as well as that of variable replacement cost. The modified cost functions for implementing both individual and group replacements were derived. The modified cost functions were minimized using the principle of classical optimization in order to find the age at which replacement of items would be appropriate. Conditions under which the individual and group replacement policies should be adopted were derived. Two real data sets on failure time of LED bulbs and their replacement costs were used to validate the theoretical claims of this work. In essence, goodness-of-fit test was used to select appropriate probability distribution of failure times as well as that of replacement costs for data sets I and II respectively. The goodness-of-fit results showed that failure times of LED bulbs follow the Smallest Extreme Value and Laplace distributions for data sets I and II respectively. Similarly, it was observed that individual replacement cost followed the two-parameter Gamma and Largest Extreme Value distributions for data sets I and II respectively. Further, the group replacement cost was found to follow the log-normal and two-parameter Weibull distributions for data sets I and II respectively. Based on the empirical study, we observed that individual replacement policy is better than group replacement policy in terms of cost minimization for both existing model and the proposed model. In view of the results, the proposed replacement policy was recommended over the existing one because it yielded lower replacement costs than the existing replacement model.展开更多
End-Stage Renal Disease (ESRD) represents one of the most challenging social and medical problems mainly due to substantial treatment-associated costs. The chronic nature of the disease needs expensive continuous care...End-Stage Renal Disease (ESRD) represents one of the most challenging social and medical problems mainly due to substantial treatment-associated costs. The chronic nature of the disease needs expensive continuous care that majority of the patients cannot afford. Therefore, in many countries expenses associated with the ESRD treatment is paid by state government. These treatment options include: hemodialysis, peritoneal dialysis and kidney transplantation. Multiple studies have been conducted throughout the world to assess cost-effectiveness of these treatment modalities. The studies suggest that kidney transplantation not only reduces mortality and morbidity but improves a quality of life of ESRD patients. Furthermore, it is the most cost-effective treatment for the ESRD at least in high-income countries. The goal of our study was to determine whether above-mentioned is true for lower middle income countries, where the cost of the ESRD treatment is substantially lower. Despite the low dialysis costs, transplantation remains the cheapest form of renal replacement therapy RRT in lower income countries like Georgia. Our results reveal, that kidney transplantation is most expensive modality of Renal Replacement Therapy (RRT) at month 1, but count of costs reveals that after the 10th month of treatment, the cumulative cost of transplantation is less than the cumulative cost of peritoneal dialysis and after the 23<sup>rd</sup> month, cumulative cost of hemodialysis also surpasses the cumulative cost of transplantation-related treatment and this cost comparison is in line with global data from upper-middle and high income countries.展开更多
The reliability of the product sold under a warranty is usually maintained by the manufacturer during the warranty period. After the expiry of the warranty, however, the consumer confronts a problem about how to maint...The reliability of the product sold under a warranty is usually maintained by the manufacturer during the warranty period. After the expiry of the warranty, however, the consumer confronts a problem about how to maintain the reliability of the product. This paper proposes, from the consumer's perspective, a replacement policy after the extended warranty, under the assumption that the product is sold under the renewable free replacement warranty (RFRW) policy in which the replacement is dependent on the repair-cost threshold. The proposed replacement policy is the replacement after the extended warranty is performed by the consumer based on the repair-cost threshold or preventive replacement (PR) age, which are decision variables. The expected cost rate model is derived from the consumer's perspective. The existence and uniqueness of the optimal solution that minimizes the expected cost rate per unit time are offered. Finally, a numerical example is presented to exemplify the proposed model.展开更多
Component reallocation(CR)is receiving increasing attention in many engineering systems with functionally interchangeable and unbalanced degradation components.This paper studies a CR and system replacement maintenanc...Component reallocation(CR)is receiving increasing attention in many engineering systems with functionally interchangeable and unbalanced degradation components.This paper studies a CR and system replacement maintenance policy of series repairable systems,which undergoes minimal repairs for each emergency failure of components,and considers constant downtime and cost of minimal repair,CR and system replacement.Two binary mixed integer nonlinear programming models are respectively established to determine the assignment of CR,and the uptime right before CR and system replacement with the objective of minimizing the system average maintenance cost and maximizing the system availability.Further,we derive the optimal uptime right before system replacement with maximization of the system availability,and then give the relationship between the system availability and the component failure rate.Finally,numerical examples show that the CR and system replacement maintenance policy can effectively reduce the system average maintenance cost and improve the system availability,and further give the sensitivity analysis and insights of the CR and system replacement maintenance policy.展开更多
We consider a replacement policy for a multiple-component cold-standbysystem, and after we analyze this policy, we want to get the mean total cost rate and the preventivepolicy to make it the lowest. In this system, t...We consider a replacement policy for a multiple-component cold-standbysystem, and after we analyze this policy, we want to get the mean total cost rate and the preventivepolicy to make it the lowest. In this system, the failure rate of the component in operation isconstant, and the inspection will control all the processes of the operation. The system isinspected 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.展开更多
The"replacement of business tax by VAT reform"(hereby refer to as"VAT reform"for short)is a newly promulgated and implemented tax policy,and its impact on various industries in China is very differ...The"replacement of business tax by VAT reform"(hereby refer to as"VAT reform"for short)is a newly promulgated and implemented tax policy,and its impact on various industries in China is very different,and the highway project industry is no exception.The implementation of the"VAT reform"will not only have a positive impact on the cost of highway projects,but will also have some negative impacts.For this reason,highway project construction corporates must actively respond.The author explores and analyzes the positive and negative effects of the"VAT reform"on the cost of highway projects,and proposes a reform strategy for highway project cost work under the background of the"VAT reform",in hope of helping with bringing out the intrinsic value of highway project cost management work.展开更多
AIM To collect data from joint replacement in inhibitor patients, evaluate haemostatic and patient outcomes, and analyse the costs.METHODS We report our 21-year, single-centre cumulative experience of 15 joint arthrop...AIM To collect data from joint replacement in inhibitor patients, evaluate haemostatic and patient outcomes, and analyse the costs.METHODS We report our 21-year, single-centre cumulative experience of 15 joint arthroplasties in six inhibitor patients.RESULTS Two low responder inhibitor patients were in the early days treated with FVIII, whereas bypassing agents were used in the rest of the high responder patients. The primary haemostatic outcome was good in 8/15, fair in 4/15 and poor in 3/15 operations. The overall patient outcome, including joint health and patient satisfaction, was good in 10/15, fair 4/15 and poor in 1/15. No deep infections were observed. Cost analysis was most beneficial in low responders and in two immune-tolerized, high responder patients. In all cases, factor replacement comprised the main treatment costs.CONCLUSION Our experience supports the initial use of bypassing agents as well as preoperative immune-tolerance induction when possible. Despite the challenges of haemostasis and severe joint disease, total joint arthroplasty can reach a good outcome, even in inhibitor patients. The risk for deep infection might be smaller than previously reported. Individual planning, intense multidisciplinary teamworkand execution of operations should be centralised in a professional unit.展开更多
To gain a competitive edge within the international and compet让ive setting of coal markets, coal producers must find new ways of reducing costs. Increasing bench drilling efficiency and performance in open-cast coal ...To gain a competitive edge within the international and compet让ive setting of coal markets, coal producers must find new ways of reducing costs. Increasing bench drilling efficiency and performance in open-cast coal mines has the potential to generate savings. Specifically, monitoring, analyzing, and optimizing the drilling operation can reduce drilling costs. For example, determining the optimal drill bit replacement time will help to achieve the desirable penetration rate. This paper presents a life data analysis of drill bits to fit a statistical distribution using failure records. These results are then used to formulate a cost minimization problem to estimate the drill bit replacement time using the evolutionary algorithm. The effect of cost on the uncertainty associated with replacement time is assessed through Monte-Carlo simulation. The relationship between the total expected replacement cost and replacement time is also presented. A case study shows that the proposed approach can be used to assist with designing a drill bit replacement schedule and minimize costs in open-cast coal mines.展开更多
The operation of distribution system with the components in deteriorating condition makes the system reliability worsen. It is important to find the solution for balancing failure cost and maintenance benefits such as...The operation of distribution system with the components in deteriorating condition makes the system reliability worsen. It is important to find the solution for balancing failure cost and maintenance benefits such as down-time and reliability. In this paper, time to replace the components in optimum condition based on constant-interval replacement mode is investigated. The optimal replacement time is mainly depended on component’s reliability and the cost ration of preventive replacement and failure replacement. In this paper, equipment inspection method and Weibull Analysis is applied to obtain the accurate reliability estimation. Weibull Analysis is applied with constant-interval replacement model to investigate the optimum replacement time for each component considering the different cost ratios. According to the quantitative results, the determination of the optimal replacement time (OPT) can minimize the total downtime and failure cost. Consequently, the reliability of the system is maximized and estimation also becomes more accurate due to sufficient approach.展开更多
On the basis of describing the connotation of agricultural intangible asset and cost method,the technical ideas of appraising by cost method are introduced.The article analyzes the advantages(simple appraisal principl...On the basis of describing the connotation of agricultural intangible asset and cost method,the technical ideas of appraising by cost method are introduced.The article analyzes the advantages(simple appraisal principle and easy to understand and grasp;overall consideration of various factors related to appraisal result value) and disadvantages(high appraisal cost;difficult to appraise and grasp various appraisal factors) of appraising by cost method.The article also summarizes the precondition of appraising by cost method:it is applicable to appraise the agricultural intangible asset which can be reproduced and afresh developed.Based on the cognition of agricultural intangible asset and the relevant rules of Ministry of Finance on appraisal of intangible asset by using cost method,the model of appraising agricultural intangible asset by cost method is constructed.That is:agricultural intangible asset value = replacement cost of agricultural intangible asset ×newness rate + opportunity cost of agricultural intangible asset.Determine and analyze parameters of the model,in order to offer references for appraisers to appraise agricultural intangible asset value more reasonably.展开更多
文摘Several researches have been done to provide better alternative to the existing replacement models, but the research works did not adequately address the replacement problem for items that fail suddenly. Hence, a modified replacement model for items that fail suddenly has been proposed using the knowledge of probability distribution of failure times as well as that of variable replacement cost. The modified cost functions for implementing both individual and group replacements were derived. The modified cost functions were minimized using the principle of classical optimization in order to find the age at which replacement of items would be appropriate. Conditions under which the individual and group replacement policies should be adopted were derived. Two real data sets on failure time of LED bulbs and their replacement costs were used to validate the theoretical claims of this work. In essence, goodness-of-fit test was used to select appropriate probability distribution of failure times as well as that of replacement costs for data sets I and II respectively. The goodness-of-fit results showed that failure times of LED bulbs follow the Smallest Extreme Value and Laplace distributions for data sets I and II respectively. Similarly, it was observed that individual replacement cost followed the two-parameter Gamma and Largest Extreme Value distributions for data sets I and II respectively. Further, the group replacement cost was found to follow the log-normal and two-parameter Weibull distributions for data sets I and II respectively. Based on the empirical study, we observed that individual replacement policy is better than group replacement policy in terms of cost minimization for both existing model and the proposed model. In view of the results, the proposed replacement policy was recommended over the existing one because it yielded lower replacement costs than the existing replacement model.
文摘End-Stage Renal Disease (ESRD) represents one of the most challenging social and medical problems mainly due to substantial treatment-associated costs. The chronic nature of the disease needs expensive continuous care that majority of the patients cannot afford. Therefore, in many countries expenses associated with the ESRD treatment is paid by state government. These treatment options include: hemodialysis, peritoneal dialysis and kidney transplantation. Multiple studies have been conducted throughout the world to assess cost-effectiveness of these treatment modalities. The studies suggest that kidney transplantation not only reduces mortality and morbidity but improves a quality of life of ESRD patients. Furthermore, it is the most cost-effective treatment for the ESRD at least in high-income countries. The goal of our study was to determine whether above-mentioned is true for lower middle income countries, where the cost of the ESRD treatment is substantially lower. Despite the low dialysis costs, transplantation remains the cheapest form of renal replacement therapy RRT in lower income countries like Georgia. Our results reveal, that kidney transplantation is most expensive modality of Renal Replacement Therapy (RRT) at month 1, but count of costs reveals that after the 10th month of treatment, the cumulative cost of transplantation is less than the cumulative cost of peritoneal dialysis and after the 23<sup>rd</sup> month, cumulative cost of hemodialysis also surpasses the cumulative cost of transplantation-related treatment and this cost comparison is in line with global data from upper-middle and high income countries.
基金supported by the National Natural Science Foundation of China(7147114771631001)+1 种基金the Basic Research Project of Natural Science in Shaanxi Province(2015JQ7273)the 111 Project(B13044)
文摘The reliability of the product sold under a warranty is usually maintained by the manufacturer during the warranty period. After the expiry of the warranty, however, the consumer confronts a problem about how to maintain the reliability of the product. This paper proposes, from the consumer's perspective, a replacement policy after the extended warranty, under the assumption that the product is sold under the renewable free replacement warranty (RFRW) policy in which the replacement is dependent on the repair-cost threshold. The proposed replacement policy is the replacement after the extended warranty is performed by the consumer based on the repair-cost threshold or preventive replacement (PR) age, which are decision variables. The expected cost rate model is derived from the consumer's perspective. The existence and uniqueness of the optimal solution that minimizes the expected cost rate per unit time are offered. Finally, a numerical example is presented to exemplify the proposed model.
基金supported by the National Natural Science Foundation of China(72101025,72271049)the Fundamental Research Funds for the Central Universities(FRF-TP-20-073A1)the China Postdoct oral Science Foundation(2021M690349)。
文摘Component reallocation(CR)is receiving increasing attention in many engineering systems with functionally interchangeable and unbalanced degradation components.This paper studies a CR and system replacement maintenance policy of series repairable systems,which undergoes minimal repairs for each emergency failure of components,and considers constant downtime and cost of minimal repair,CR and system replacement.Two binary mixed integer nonlinear programming models are respectively established to determine the assignment of CR,and the uptime right before CR and system replacement with the objective of minimizing the system average maintenance cost and maximizing the system availability.Further,we derive the optimal uptime right before system replacement with maximization of the system availability,and then give the relationship between the system availability and the component failure rate.Finally,numerical examples show that the CR and system replacement maintenance policy can effectively reduce the system average maintenance cost and improve the system availability,and further give the sensitivity analysis and insights of the CR and system replacement maintenance policy.
文摘We consider a replacement policy for a multiple-component cold-standbysystem, and after we analyze this policy, we want to get the mean total cost rate and the preventivepolicy to make it the lowest. In this system, the failure rate of the component in operation isconstant, and the inspection will control all the processes of the operation. The system isinspected 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.
文摘The"replacement of business tax by VAT reform"(hereby refer to as"VAT reform"for short)is a newly promulgated and implemented tax policy,and its impact on various industries in China is very different,and the highway project industry is no exception.The implementation of the"VAT reform"will not only have a positive impact on the cost of highway projects,but will also have some negative impacts.For this reason,highway project construction corporates must actively respond.The author explores and analyzes the positive and negative effects of the"VAT reform"on the cost of highway projects,and proposes a reform strategy for highway project cost work under the background of the"VAT reform",in hope of helping with bringing out the intrinsic value of highway project cost management work.
文摘AIM To collect data from joint replacement in inhibitor patients, evaluate haemostatic and patient outcomes, and analyse the costs.METHODS We report our 21-year, single-centre cumulative experience of 15 joint arthroplasties in six inhibitor patients.RESULTS Two low responder inhibitor patients were in the early days treated with FVIII, whereas bypassing agents were used in the rest of the high responder patients. The primary haemostatic outcome was good in 8/15, fair in 4/15 and poor in 3/15 operations. The overall patient outcome, including joint health and patient satisfaction, was good in 10/15, fair 4/15 and poor in 1/15. No deep infections were observed. Cost analysis was most beneficial in low responders and in two immune-tolerized, high responder patients. In all cases, factor replacement comprised the main treatment costs.CONCLUSION Our experience supports the initial use of bypassing agents as well as preoperative immune-tolerance induction when possible. Despite the challenges of haemostasis and severe joint disease, total joint arthroplasty can reach a good outcome, even in inhibitor patients. The risk for deep infection might be smaller than previously reported. Individual planning, intense multidisciplinary teamworkand execution of operations should be centralised in a professional unit.
文摘To gain a competitive edge within the international and compet让ive setting of coal markets, coal producers must find new ways of reducing costs. Increasing bench drilling efficiency and performance in open-cast coal mines has the potential to generate savings. Specifically, monitoring, analyzing, and optimizing the drilling operation can reduce drilling costs. For example, determining the optimal drill bit replacement time will help to achieve the desirable penetration rate. This paper presents a life data analysis of drill bits to fit a statistical distribution using failure records. These results are then used to formulate a cost minimization problem to estimate the drill bit replacement time using the evolutionary algorithm. The effect of cost on the uncertainty associated with replacement time is assessed through Monte-Carlo simulation. The relationship between the total expected replacement cost and replacement time is also presented. A case study shows that the proposed approach can be used to assist with designing a drill bit replacement schedule and minimize costs in open-cast coal mines.
文摘The operation of distribution system with the components in deteriorating condition makes the system reliability worsen. It is important to find the solution for balancing failure cost and maintenance benefits such as down-time and reliability. In this paper, time to replace the components in optimum condition based on constant-interval replacement mode is investigated. The optimal replacement time is mainly depended on component’s reliability and the cost ration of preventive replacement and failure replacement. In this paper, equipment inspection method and Weibull Analysis is applied to obtain the accurate reliability estimation. Weibull Analysis is applied with constant-interval replacement model to investigate the optimum replacement time for each component considering the different cost ratios. According to the quantitative results, the determination of the optimal replacement time (OPT) can minimize the total downtime and failure cost. Consequently, the reliability of the system is maximized and estimation also becomes more accurate due to sufficient approach.
文摘On the basis of describing the connotation of agricultural intangible asset and cost method,the technical ideas of appraising by cost method are introduced.The article analyzes the advantages(simple appraisal principle and easy to understand and grasp;overall consideration of various factors related to appraisal result value) and disadvantages(high appraisal cost;difficult to appraise and grasp various appraisal factors) of appraising by cost method.The article also summarizes the precondition of appraising by cost method:it is applicable to appraise the agricultural intangible asset which can be reproduced and afresh developed.Based on the cognition of agricultural intangible asset and the relevant rules of Ministry of Finance on appraisal of intangible asset by using cost method,the model of appraising agricultural intangible asset by cost method is constructed.That is:agricultural intangible asset value = replacement cost of agricultural intangible asset ×newness rate + opportunity cost of agricultural intangible asset.Determine and analyze parameters of the model,in order to offer references for appraisers to appraise agricultural intangible asset value more reasonably.
