Probabilistic cell modelling of cleavage fracture

Various aspects on probabilistic modelling of cleavage fracture are discussed. The investigation involves consideration of a unit cell with an explicitly modelled void. The results from this model are compared with results for the case when the void content is accounted for in the sense of a Gurson-Tvergaard law. It is found that explicit modelling of the void can give substantially different results for the fracture probability. The effect depends on the exponent in the assumed Weibull distribution, the threshold stress, the constraint conditions and the hardening of the material. This revised version was published online in August 2006 with corrections to the Cover Date.     

Luminescent Efficiency in Single-layer Organic Electrophosphorescent Devices

Based on the charge injection and recombination processes and the triplet-triplet annihilation process, a model to calculate the electro.luminescent（EL） efficiency is presented. The influences of the applied electric field on the injection efficiency, recombination efficiency and electroluminescent efficiency are discussed. It is found that： （1） The injection efficiency is increasing while the recombination efficiency is decreasing with the applied electric field increasing. （2） The EL efficiency is enhanced at low electric field slowly but is decreasing at high electric field with the increase of applied voltage. （3） The EL efficiency is decreasing with the increase of the host-guest molecular distance （R）. So, it is concluded that the EL efficiency in single-layer organic electrophosphorescent devices is dominated by injection efficiency at lower electric field and recombination efficiency at higher electric field.     

Optimal search for signals in a multichannel system: Arbitrary initial distribution in state space merging scheme

Markovian and semi-Markovian random processes are used to analyze the problem of optimal search for signals in a multichannel communication system with arbitrarily distributed random outputs. The search efficiency factor is found in explicit form based on state space merging, and a mathematical programming problem is set up to find a numerical suboptimal solution. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 144–150, May–June 2007.     

马尔可夫链在产品可靠性预测中的应用

事物未来的状态仅仅受事物现状的影响，而与过去的状态无关，也就是具有马尔可夫性。用马尔可夫链的理论与方法，对具有马尔可夫性产品的可靠性进行预测，既为产品的可靠性设计和产品售后服务的经济性分析提供了参考，也为马尔可夫模型的实际应用拓广了范围。通过实例说明在数学软件的帮助下这种预测方法的简单可行性。     

N_2/Fe(100)相互作用的动力学研究

用准经典轨迹法对N2－Fe（100）系统进行了研究，分析了氮分子在Fe（100）面上的直接散射和离解性吸附等过程中的能量传递和重新分配，阐明了表面催化的机理。作为准经典轨迹法更为深入的应用，研究了主要LEPS势参数和势特性对初始离解吸附几率（S0）的影响，得出了S0随势特性变化的规律。     

钻井岩屑粒径分布规律的研究

钻井振动筛是固控系统的重要分离设备,其主要任务是清除钻井液中直径大于74μm的固相颗粒。对辽河油田7口井深0～3500m的钻井岩屑进行了实地取样,分析了岩样颗粒直径大于74μm的粒径分布特征。分析结果表明,钻井岩屑具有明显的片状特征,颗粒的粒径分布主要与地层岩性和破岩工具有关,随着井深的变化,其岩样粒径分布呈现出幂分布、2分布和瑞利分布等3组典型规律。给出了岩屑颗粒的概率直径;建议在筛面颗粒运动特性研究、筛网工作载荷的计算和激振方式的选择中,应考虑岩屑颗粒片状特性的影响。     

济阳坳陷储量规模升级风险评价方法

针对应用浆特卡洛法进行储量风险评价时存在操作繁琐的弊端，从储量升级前后对比入手，提出利用累积概率图版进行储量升级风险的评价方法，通过分析济阳坳陷控制储量、预测储量和圈闭资源量等最终升级探明储量资料，建立了该区低级别储量升级探明储量风险评价图版。研究结果表明，地质认识程度是影响各级储量目标升级比啻5的重要因素，其中探井密度是影响济阳坳陷控制储量升级的主要原因。运用该图版对低级别储量目标进行定量风险评价时，累积概率值能够反映出不能达到各预期升级结果的可能性，一般来说，预期值越大，累积概率值越大，风险也就越高。在罗151块的应用结果证明了该方法能为正确的勘探决策提供依据。     

不确定移动对象概率Skyline集的查询更新

Skyline查询的研究已从传统的静态Skyline操作延伸到动态的、不确定数据集上的Skyline查询和计算上。研究了移动环境下,查询点位置固定、目标点处于运动状态并且位置不确定情况下的连续概率Skyline计算问题。这个过程中,移动对象与查询对象之间的距离随时间不断变化。移动对象由于其运动状态导致位置无法精确定位,因此移动对象之间的支配关系只能采用概率形式表示,且随时间不断变化。给出了移动对象间的支配概率的定义,以及移动对象Skyline概率的定义,并定义了触发事件来记录对象支配概率发生变化的时刻,实现概率Skyline计算的连续跟踪和动态更新。提出了基于事件触发的连续概率Skyline查询算法(event triggered continuous probabilistic Skyline query for uncertain moving object,U-ECPS),对移动环境下的Skyline集进行连续查询和更新。大量的实验结果验证了U-ECPS算法的有效性。