A note on the first-passage problem and VanMarcke’s approximation — short communication

Given a scalar, stationary, Markov process, this short communication presents a closed-form solution for the first-passage problem for a fixed threshold b. The derivation is based on binary processes and the general formula of Siegert [Siegert AJF. On the first-passage time probability problem. Physical Review 1951; 81:617–23]. The relation for the probability density function of the first-passage time is identical to the commonly used formula that was derived by VanMarcke [VanMarcke E. On the distribution of the first-passage time for normal stationary random processes. Journal of Applied Mechanics ASME 1975; 42:215–20] for Gaussian processes. The present derivation is based on more general conditions and reveals the criteria for the validity of the approximation. Properties of binary processes are also used to derive a hierarchy of upper bounds for any scalar process.     

Markov不等式与H(?)lder不等式的差异性

通过对(李亚普诺夫)不等式的证明,论证了Markov不等式及Holder不等式的差异性,同时讨论了2个不等式的适应范围。     

新岭大桥转体施工技术

新岭大桥采用有平衡重的平面转体法施工 ,这在我省尚属首例。施工中因地制宜采用拉链葫芦滑轮组进行牵引 ,仅用 3小时就使拱肋平稳、安全地转体就位 ,牵引施工获得成功 ,为我省的桥梁施工积累了经验 ,具有推广价值     

A bi-criteria model for the inventory aggregation problem under risk pooling

Inventory aggregation, also called Risk Pooling, is one of the most efficient ways to reduce the level of safety stocks thereby reducing inventory across the supply chain. Determining the best level of aggregation is a difficult problem and needs extensive study of all the possible scenarios that can affect this decision. Minimizing costs in a supply chain is no longer the sole priority of businesses. Maintaining a high level of responsiveness is also considered equally important. The conflicting nature of these two criteria makes the solution of the problem difficult. In this paper, we develop a bi-criteria nonlinear stochastic integer programming model to determine the best supply chain distribution network to meet customer demands, where minimizing costs while maintaining high levels of responsiveness is important. We develop a two-stage optimization algorithm to solve this problem.     

动态力学及介电法研究蓖麻油丙烯酸酯共聚网络悬挂链的弛豫运动

用动态力学（内耗）和介电方法研究了由蓖麻油（ｃａｓｔｏｒｏｉｌ）、甲苯二异氰酸酯（ＴＤＩ）、丙烯酸羟乙酯（ＨＥＭＡ）组成的网络（Ａｉ）和由正己醇取代Ａ网络中部分ＨＥＭＡ组成的网络Ｂｉ（ｉ＝０，１，２，３）两种网络的内耗及介电损耗，内耗峰强度随悬挂链数目增加而升高，证实了网络破坏后形成的悬挂链的运动对内耗及介电损耗峰高有明显的贡献。     

基于模糊修正熵权TOPSIS的战时装备供应链风险评估

针对战时装备供应链的特点,以远程精确打击、敌特后方袭扰和恶劣天气等三个因素为主要风险指标,运用修正的模糊信息熵权对TOPSIS法进行改进,提出了一种新的战时装备供应链风险评估方法。首先利用原始数据产生的模糊信息熵权进行客观赋权,并引入专家因素对权重进行主观修正,利用逼近理想解排序方法进行运算,最后通过实例计算与分析,验证该评估方法简便易行,结论合理,有效降低了指挥员决策的主观随意性。     

基于马尔科夫链的组密钥更新代价分析方法

组密钥管理机制大多基于树结构或星结构。在这两种结构中,成员的加入和离开均对密钥更新代价影响很大。提出基于连续时间马可夫链的代价更新分析方法,利用连续时间马可夫链来模拟成员动态变化,并对星结构和树结构的组播密钥管理方案进行更新代价仿真分析,并比较了两者的性能差异。仿真结果表明,组成员离开的概率和速率是影响星结构和树结构密钥管理方案在密钥更新代价上差异的主要因素。因此,在动态变化的环境下,应使用星结构和树结构相结合的组密钥管理机制。     

采用B/S架构设计与实现超市配送系统

系统采用B/S架构。整个系统由六大模块构成,分别是人员基本信息管理模块、商品信息管理模块、连锁店管理模块、商品入库管理模块、商品配送管理模块、退出系统模块。整个系统能够独立运行,使用方便,能够及时地分析企业进销存情况,提高工作效率,能给企业带来更大的利益。     

Driving intention recognition and behaviour prediction based on a double-layer hidden Markov model

We propose a model structure with a double-layer hidden Markov model (HMM) to recognise driving intention and predict driving behaviour. The upper-layer multi-dimensional discrete HMM (MDHMM) in the double-layer HMM represents driving intention in a combined working case, constructed according to the driving behaviours in certain single working cases in the lower-layer multi-dimensional Gaussian HMM (MGHMM). The driving behaviours are recognised by manoeuvring the signals of the driver and vehicle state information, and the recognised results are sent to the upper-layer HMM to recognise driving intentions. Also, driving behaviours in the near future are predicted using the likelihood-maximum method. A real-time driving simulator test on the combined working cases showed that the double-layer HMM can recognise driving intention and predict driving behaviour accurately and efficiently. As a result, the model provides the basis for pre-warning and intervention of danger and improving comfort performance.