Rational planning of spares configuration project is an effective approach to improve equipment availability as well as reduce life cycle cost （LCC）. With an analysis of various impacts on support system, the spares...Rational planning of spares configuration project is an effective approach to improve equipment availability as well as reduce life cycle cost （LCC）. With an analysis of various impacts on support system, the spares demand rate forecast model is constructed. According to systemic analysis method, spares support effectiveness evaluation indicators system is built, and then, initial spares configuration and optimization method is researched. To the issue of discarding and con-sumption for incomplete repairable items, its expected backorders function is approximated by Laplace demand distribution. Combining the （s-1, s） and （R, Q） inventory policy, the spares resup-ply model is established under the batch ordering policy based on inventory state, and the optimi-zation analysis flow for spares configuration is proposed. Through application on shipborne equipment spares configuration, the given scenarios are analyzed under two constraint targets：one is the support effectiveness, and the other is the spares cost. Analysis reveals that the result is consistent with practical regulation;therefore, the model＇s correctness, method＇s validity as well as optimization project＇s rationality are proved to a certain extent.展开更多
The repeated failures of any equipment or systems are modeled as a renewal process. The management needs an assessment of the number of future failures to allocate the resources needed for fast repairs. Based on the i...The repeated failures of any equipment or systems are modeled as a renewal process. The management needs an assessment of the number of future failures to allocate the resources needed for fast repairs. Based on the idea of expectation by conditioning, special Volterra-type integral equations are derived for general types of repairs, considering the length of repair and reduced degradation of the idle object. In addition to minimal repair and failure replacement, partial repairs are also discussed when the repair results in reduction of the number of future failures or decreases the effective age of the object. Numerical integration-based algorithm and simulation study are performed to solve the resulting integral equation. Since the geometry degradation in different dimensions of a rail track and controlling and maintaining defects are of importance, a numerical example using the rail industry data is conducted. Expected number of failures of different failure type modes in rail track is calculated within a two-year interval. Results show that within a two-year period, anticipated occurrences of cross level failures, surface failures, and DPI failures are 2.4, 3.8, and 5.8, respectively.展开更多
I consider a system whose deterioration follows a discrete-time and discrete-state Markov chain with an absorbing state. When the system is put into practice, I may select operation (wait), imperfect repair, or replac...I consider a system whose deterioration follows a discrete-time and discrete-state Markov chain with an absorbing state. When the system is put into practice, I may select operation (wait), imperfect repair, or replacement at each discrete-time point. The true state of the system is not known when it is operated. Instead, the system is monitored after operation and some incomplete information concerned with the deterioration is obtained for decision making. Since there are multiple imperfect repairs, I can select one option from them when the imperfect repair is preferable to operation and replacement. To express this situation, I propose a POMDP model and theoretically investigate the structure of an optimal maintenance policy minimizing a total expected discounted cost for an unbounded horizon. Then two stochastic orders are used for the analysis of our problem.展开更多
目的探讨关节镜下部分修补老年性巨大肩袖损伤的临床效果。方法回顾性分析2012年1月至2014年6月关节镜下部分修补老年性巨大肩袖损伤的患者58例,其中男27例,女31例;左侧11例,右侧47例,平均年龄57.5岁。应用美国肩肘外科医师评分（Americ...目的探讨关节镜下部分修补老年性巨大肩袖损伤的临床效果。方法回顾性分析2012年1月至2014年6月关节镜下部分修补老年性巨大肩袖损伤的患者58例,其中男27例,女31例;左侧11例,右侧47例,平均年龄57.5岁。应用美国肩肘外科医师评分（American Shoulder and Elbow Surgeons,ASES）、Constant-Murley肩关节功能评分、美国加利福尼亚大学洛杉矶分校（University of California,Los Angeles,UCLA）评分记录术前及术后最终随访时的肩关节疼痛、肩关节活动范围、前屈上举肌力、外展强度的情况。结果 58例患者均获得有效随访,患者术程顺利,术后获18~26个月（平均23.2个月）随访。术前ASES评分为（8.2±1.4）分,Constant评分为（37.1±7.2）分,UCLA评分为（8.7±2.5）分;术后18个月ASES评分为（28.5±4.5）分,Constant评分为（84.6±4.7）分,UCLA评分为（28.4±4.5）分。术后18个月与术前比较,差异有统计学意义（P〈0.05）。结论关节镜下部分修补老年性巨大肩袖损伤的治疗效果满意,可获得良好的肩关节功能。展开更多
基金co-supported by the General Armament Department Pre-research Foundation of China (Nos. 51304010206, 51327 020105)
文摘Rational planning of spares configuration project is an effective approach to improve equipment availability as well as reduce life cycle cost （LCC）. With an analysis of various impacts on support system, the spares demand rate forecast model is constructed. According to systemic analysis method, spares support effectiveness evaluation indicators system is built, and then, initial spares configuration and optimization method is researched. To the issue of discarding and con-sumption for incomplete repairable items, its expected backorders function is approximated by Laplace demand distribution. Combining the （s-1, s） and （R, Q） inventory policy, the spares resup-ply model is established under the batch ordering policy based on inventory state, and the optimi-zation analysis flow for spares configuration is proposed. Through application on shipborne equipment spares configuration, the given scenarios are analyzed under two constraint targets：one is the support effectiveness, and the other is the spares cost. Analysis reveals that the result is consistent with practical regulation;therefore, the model＇s correctness, method＇s validity as well as optimization project＇s rationality are proved to a certain extent.
文摘The repeated failures of any equipment or systems are modeled as a renewal process. The management needs an assessment of the number of future failures to allocate the resources needed for fast repairs. Based on the idea of expectation by conditioning, special Volterra-type integral equations are derived for general types of repairs, considering the length of repair and reduced degradation of the idle object. In addition to minimal repair and failure replacement, partial repairs are also discussed when the repair results in reduction of the number of future failures or decreases the effective age of the object. Numerical integration-based algorithm and simulation study are performed to solve the resulting integral equation. Since the geometry degradation in different dimensions of a rail track and controlling and maintaining defects are of importance, a numerical example using the rail industry data is conducted. Expected number of failures of different failure type modes in rail track is calculated within a two-year interval. Results show that within a two-year period, anticipated occurrences of cross level failures, surface failures, and DPI failures are 2.4, 3.8, and 5.8, respectively.
文摘I consider a system whose deterioration follows a discrete-time and discrete-state Markov chain with an absorbing state. When the system is put into practice, I may select operation (wait), imperfect repair, or replacement at each discrete-time point. The true state of the system is not known when it is operated. Instead, the system is monitored after operation and some incomplete information concerned with the deterioration is obtained for decision making. Since there are multiple imperfect repairs, I can select one option from them when the imperfect repair is preferable to operation and replacement. To express this situation, I propose a POMDP model and theoretically investigate the structure of an optimal maintenance policy minimizing a total expected discounted cost for an unbounded horizon. Then two stochastic orders are used for the analysis of our problem.
文摘目的探讨关节镜下部分修补老年性巨大肩袖损伤的临床效果。方法回顾性分析2012年1月至2014年6月关节镜下部分修补老年性巨大肩袖损伤的患者58例,其中男27例,女31例;左侧11例,右侧47例,平均年龄57.5岁。应用美国肩肘外科医师评分（American Shoulder and Elbow Surgeons,ASES）、Constant-Murley肩关节功能评分、美国加利福尼亚大学洛杉矶分校（University of California,Los Angeles,UCLA）评分记录术前及术后最终随访时的肩关节疼痛、肩关节活动范围、前屈上举肌力、外展强度的情况。结果 58例患者均获得有效随访,患者术程顺利,术后获18~26个月（平均23.2个月）随访。术前ASES评分为（8.2±1.4）分,Constant评分为（37.1±7.2）分,UCLA评分为（8.7±2.5）分;术后18个月ASES评分为（28.5±4.5）分,Constant评分为（84.6±4.7）分,UCLA评分为（28.4±4.5）分。术后18个月与术前比较,差异有统计学意义（P〈0.05）。结论关节镜下部分修补老年性巨大肩袖损伤的治疗效果满意,可获得良好的肩关节功能。
