低轨卫星移动通信系统馈电链路切换方案

研究了无星际链路低轨卫星移动通信系统中的馈电链路的切换问题,提出了两种馈电切换方案-最短馈电链路切换方案和最长可视时间切换方案。结合两种已有的用户链路切换准则,在构造的非均匀分布全国话务密度模型上进行了系统仿真。仿真结果表明馈电链路切换方案对系统开销影响较大,选择最长可视时间馈电链路切换方案,可以减少切换带来的信令开销,提高服务质量,具有较高的参考和实用价值。     

A tutorial on adaptive MCMC

We review adaptive Markov chain Monte Carlo algorithms (MCMC) as a mean to optimise their performance. Using simple toy examples we review their theoretical underpinnings, and in particular show why adaptive MCMC algorithms might fail when some fundamental properties are not satisfied. This leads to guidelines concerning the design of correct algorithms. We then review criteria and the useful framework of stochastic approximation, which allows one to systematically optimise generally used criteria, but also analyse the properties of adaptive MCMC algorithms. We then propose a series of novel adaptive algorithms which prove to be robust and reliable in practice. These algorithms are applied to artificial and high dimensional scenarios, but also to the classic mine disaster dataset inference problem.     

A response to M. Stone: 'How not to measure the efficiency of public services (and how one might)'

Summary.  This is a response to Stone's criticisms of the Spottiswoode report to the UK Treasury which was responding to the Treasury's request for improved methods to evaluate the efficiency and productivity of the 43 police districts in England and Wales. The Spottiswoode report recommended uses of data envelopment analysis (DEA) and stochastic frontier analysis (SFA), which Stone critiqued en route to proposing an alternative approach. Here we note some of the most serious errors in his criticism and inaccurate portrayals of DEA and SFA. Most of our attention is devoted to DEA, and to Stone's recommended alternative approach without much attention to SFA, partly because of his abbreviated discussion of the latter. In our response we attempt to be constructive as well as critical by showing how Stone's proposed approach can be joined to DEA to expand his proposal beyond limitations in his formulations.     

Nonconglomerative coherent conditional probabilities in statistical inference

Noteworthy connections among conglomerability, countable additivity and coherence are discussed in detail, reaching the conclusion that nonconglomerable conditional probabilities must not be doomed and play a significant role in statistical inference. Extended and updated version of a contributed paper presented at the International Conference on “Information Processing and Management of Uncertainty in knowledge-based systems”, IPMU 2004, Perugia, Italy.     

论大学物理与中学物理教学的衔接

主要阐述了大学物理与中学物理教学现状,分析了大学物理与中学物理教学脱节的原因,并依据建构主义理论提出了解决教学衔接问题的相应措施.     

Newsvendor Problems with Demand Shocks and Unknown Demand Distributions

In today's competitive market, demand volume and even the underlying demand distribution can change quickly for a newsvendor seller. We refer to sudden changes in demand distribution as demand shocks. When a newsvendor seller has limited demand distribution information and also experiences underlying demand shocks, the majority of existing methods for newsvendor problems may not work well since they either require demand distribution information or assume stationary demand distribution. We present a new, robust, and effective machine learning algorithm for newsvendor problems with demand shocks but without any demand distribution information. The algorithm needs only an approximate estimate of the lower and upper bounds of demand range; no other knowledge such as demand mean, variance, or distribution type is necessary. We establish the theoretical bounds that determine this machine learning algorithm's performance in handling demand shocks. Computational experiments show that this algorithm outperforms the traditional approaches in a variety of situations including large and frequent shocks of the demand mean. The method can also be used as a meta‐algorithm by incorporating other traditional approaches as experts. Working together, the original algorithm and the extended meta‐algorithm can help manufacturers and retailers better adapt their production and inventory control decisions in dynamic environments where demand information is limited and demand shocks are frequent      

Managing stochastic demand in an Inventory Routing Problem with transportation procurement

We study an Inventory Routing Problem in which the supplier has a limited production capacity and the stochastic demand of the retailers is satisfied with procurement of transportation services. The aim is to minimize the total expected cost over a planning horizon, given by the sum of the inventory cost at the supplier, the inventory cost at the retailers, the penalty cost for stock-out at the retailers and the transportation cost. First, we show that a policy based just on the average demand can have a total expected cost infinitely worse than the one obtained by taking into account the overall probability distribution of the demand in the decision process. Therefore, we introduce a stochastic dynamic programming formulation of the problem that allows us to find an optimal policy in small size instances. Finally, we design and implement a matheuristic approach, integrating a rollout algorithm and an optimal solution of mixed-integer linear programming models, which is able to solve realistic size problem instances. Computational results allow us to provide managerial insights concerning the management of stochastic demand.     

加强和改进教育学公共课实践性教学环节的探讨

作者根据多年的教学经验和对在校师范生、中小学青年教师的调查，认为加强和改进实践性教学环节是当前教育学公共课改革的一个关键问题。文章分析了实践性教学环节的涵义、特点、方式、功能等理论问题，概括了师范生对教育学公共课实践性教学环节的几个具体问题的评价，并提出了拟深入研究的若干重要问题     

作业评语:大学英语教学的重要环节

在大学公共英语教学中普遍存在着这样一种现象:教师只重视课堂作业的口头讲评,而忽视课后作业的书面评语。其后果是学生面对批改过的作业不知如何改正,因而达不到预期的教学效果。我们认为,英语教学方法亟待改进,英语作业评语的地位也亟待提升。英语作业评语应该是大学公共英语教学不容忽视的一个环节,这是由其自身的特点和作用决定的。     

信息网络建设:制约劳动力市场发展的一个薄弱环节

市场机制优化资源配置的前提是有充分的信息保证 ,劳动力市场的有效运作必须依靠信息支撑 ,信息网络建设是劳动力市场发展的生命线。从计划体制向市场经济体制的转型突出了劳动力信息网络建设的紧迫性 ,由于体制分割、采集手段落后、劳动力市场信息功能单一、职业介绍市场化进程滞后以及管理体制的落后制约了劳动力信息网络的发展 ,也制约了整个劳动力市场的发展。建设一个以准确性、权威性、科学性、快捷性、规范性和延伸性为要求的劳动力信息网络 ,已经成为促进并完善劳动力市场的关键环节