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51.
积分第一中值定理和第二中值定理是定积分理论中两个十分重要的定理,近年来关于其内点性的讨论非常广泛。首先根据连续函数的介值定理,用一种新方法证明积分第一中值定理的内点性;然后提出一个实例,说明积分第二中值定理在通常条件下不具有内点性;最后利用定积分存在的充要条件和Abel变换的手段,证明积分第二中值定理在加上一个非常一般化的条件时具有内点性。 相似文献
52.
将描述逻辑引入军事数据资源需求描述,提出了一种基于语义的需求描述模型,便于计算机理解和处理。介绍了该模型的内涵和总体框架,并以作战力量数据资源为例,阐述了作战力量数据资源概念术语集的构建、作战力量数据资源的表征和需求的形式化描述。依据数据需求,制定了相应推理规则,其可借助描述逻辑的可判定性实现军事数据资源需求的推理。 相似文献
53.
Demand forecasting performance is subject to the uncertainty underlying the time series an organization is dealing with. There are many approaches that may be used to reduce uncertainty and thus to improve forecasting performance. One intuitively appealing such approach is to aggregate demand in lower‐frequency “time buckets.” The approach under concern is termed to as temporal aggregation, and in this article, we investigate its impact on forecasting performance. We assume that the nonaggregated demand follows either a moving average process of order one or a first‐order autoregressive process and a single exponential smoothing (SES) procedure is used to forecast demand. These demand processes are often encountered in practice and SES is one of the standard estimators used in industry. Theoretical mean‐squared error expressions are derived for the aggregated and nonaggregated demand to contrast the relevant forecasting performances. The theoretical analysis is supported by an extensive numerical investigation and experimentation with an empirical dataset. The results indicate that performance improvements achieved through the aggregation approach are a function of the aggregation level, the smoothing constant, and the process parameters. Valuable insights are offered to practitioners and the article closes with an agenda for further research in this area. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 60: 479–498, 2013 相似文献
54.
兵团团场教师队伍结构性矛盾突出、教师编制紧张、城乡(团)收入差距较大、教师流失较严重。要通过优化教师结构、创新教师补充机制、提高教师待遇、提升教师素质,稳定团场教师队伍,促进兵团义务教育均衡发展。 相似文献
55.
56.
用电化学方法评价油膜防锈性能 总被引:2,自引:0,他引:2
用电位—时间、多重动电位扫描两种电化学方法对防锈油的防护性能进行了分析和评价 ,并与盐水浸渍试验进行了对照。结果表明 :两种电化学方法不仅与盐水浸渍试验具有良好的相关性 ,而且能够反映油膜下金属腐蚀的细微特征 ,是研究和评价防锈油较好的方法 相似文献
57.
In this paper, we extend the inventory lot‐size models to allow for inflation and fluctuating demand (which is more general than constant, increasing, decreasing, and log‐concave demand patterns). We prove that the optimal replenishment schedule not only exists but is also unique. Furthermore, we show that the total cost associated with the inventory system is a convex function of the number of replenishments. Hence, the search for the optimal number of replenishments is simplified to finding a local minimum. Finally, several numerical examples are provided to illustrate the results. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 144–158, 2001 相似文献
58.
科索沃战争是一场交战双方实力悬殊的战争。拥有高技术兵器的北约军队对主权国家南斯拉夫实施了高精度、远毁伤、非接触的空袭,而处于弱方的南联盟军民,寻找对方弱点,采取灵活战术进行反空袭作战,使北约集团也付出了很大的代价。这场战争是现代高技术条件下的一场典型的进攻与防御对抗作战,它反映了以落后技术装备遏制拥有高技术之敌进攻的特点和规律。 相似文献
59.
This paper studies a queueing system with a Markov arrival process with marked arrivals and PH‐distribution service times for each type of customer. Customers (regardless of their types) are served on a mixed first‐come‐first‐served (FCFS) and last‐come‐first‐served (LCFS) nonpreemptive basis. That is, when the queue length is N (a positive integer) or less, customers are served on an FCFS basis; otherwise, customers are served on an LCFS basis. The focus is on the stationary distribution of queue strings, busy periods, and waiting times of individual types of customers. A computational approach is developed for computing the stationary distribution of queue strings, the mean of busy period, and the means and variances of waiting times. The relationship between these performance measures and the threshold number N is analyzed in depth numerically. It is found that the variance of the virtual (actual) waiting time of an arbitrary customer can be reduced by increasing N. © 2000 John Wiley & Sons, Inc. Naval Research Logistics 47: 399–421, 2000 相似文献
60.
为提高DDR3控制器访存效率,设计了基于DDR3存储器预取访问数据长度的数据缓冲机制,将访存请求分为三种基本类型并分别排队处理,降低数据丢弃和实际动态随机访问存储器访问发生次数。针对图像和视频类应用程序的实验结果表明,相对于传统先到先服务的DDR3访存控制器,该机制取得了平均21.3%、最好51.3%的性能提升,硬件开销在可接受范围内。 相似文献