Effects of anisotropy of the turbid media on the photon penetration depth

Biomedical applications of near infrared radiation (NIR) techniques (i.e. based on light wavelengths roughly between 400 and 1100?nm) require that a preliminary estimate of the tissue volume being investigated be found. One possible estimate is the depth to which a photon penetrates a tissue before eventually emerging at a separating plane at a given time. A simple model for this problem can be based on a lattice random walk and was initially analyzed when the associated optical coefficients are isotropic with respect to the geometrical configuration. Here we include the effects of anisotropy in the optical coefficients, finding that at long times the statistical properties of the depth of penetration can be accounted for by very simple scaling factors while at short times the anisotropy effects can be quite noticeable.     

A model of inventory control

A model of inventory control is considered. It is described by a semi-Markov random walk with a negative drift at an angle of 0 < α < 90°, with positive random jumps, a delay, an absorbing screen at zero, and a reflecting screen for a > 0 at an angle α. The Laplace transformation is found for the distribution of the first moment storehouse exhaustion, and the first and the second moments are explicitly obtained. Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 50–59, July–August, 1999.     

Enumerating catastrophic fault patterns in VLSI arrays with both uni- and bidirectional links

Characterization of catastrophic fault patterns (CFPs) and their enumeration have been studied by several authors. Given a linear array with a set of bypass links, an important problem is how to count the number of CFPs. Enumeration of CFPs for two link redundancy G={1,g} has been solved for both unidirectional and bidirectional link cases. In this paper, we consider the more general case of link redundancy G={1,2,…,k,g}, 2k<g. Using random walk as a tool, we enumerate CFPs for both unidirectional and bidirectional cases.     

“三环”策略下的杨公桥立交步行空间概念性改造——城市车行高速化背景中的人本思考与设计对策

本文基于城市人本建设的核心理念,以重庆市沙坪坝区杨公桥立交步行系统的改造过程为例,通过考察城市快速干道的形成背景,论述人本设计的含义,调研步行空间的使用状态,得到概念性改造方案。由此呼吁车行与人行空间的平衡发展和车行高速化背景下的人本思考。     

步行街区设计初探

采用定性分析和实证研究相结合的方法,以西安骡马市步行街设计为例,分析研究了步行街区设计中较易出现的问题,从空间形态、交通组织等多方面,探讨了步行街区设计的要点和设计原则,以期指导实践。     

A model of finite-step random walk with absorbent boundaries

This paper proposes a model of finite-step lattice random walk with absorbent boundaries. We address a problem of optimal stop for this model, which is defined as the absorbent boundary value with maximum profit. Compared with many existing optimal stop investigations in the random process, our study only considers the small-sample behaviour (i.e., small number of steps behaviour) and does not consider the limit behaviour of the walk. The optimal stop time is given based on classical probability computation. Since the small-sample is more practical and common than the large-sample in many real world problems, the result obtained in this paper may provide some useful guidelines for real applications associated with the finite-step random walk such as the stock market and gambling games.     

Design and interpretation of cell trajectory assays

Cell trajectory data are often reported in the experimental cell biology literature to distinguish between different types of cell migration. Unfortunately, there is no accepted protocol for designing or interpreting such experiments and this makes it difficult to quantitatively compare different published datasets and to understand how changes in experimental design influence our ability to interpret different experiments. Here, we use an individual-based mathematical model to simulate the key features of a cell trajectory experiment. This shows that our ability to correctly interpret trajectory data is extremely sensitive to the geometry and timing of the experiment, the degree of motility bias and the number of experimental replicates. We show that cell trajectory experiments produce data that are most reliable when the experiment is performed in a quasi-one-dimensional geometry with a large number of identically prepared experiments conducted over a relatively short time-interval rather than a few trajectories recorded over particularly long time-intervals.     

关于小车机器人直线行走的控制分析

分析机器人的直线行走功能，建立物理模型，运用数学原理进行计算，得出小车机器人运动状态和左右轮速度的关系。进而分析小车机器人的直线控制方法，在传统命令的控制效果上，采用光电编码盘对左右轮转速采样，并以PWM方式输出，通过闭环控制的PID算法，实现对机器人行走速度的及时调整。     

规则网络中的扩散和反应──MonteCarlo模拟研究（Ⅰ）规则网络中的扩散

建立了一个较简单的、能比较有效地研究规则网络中分子扩散的随机游动试验方法。并用这一方法考察了规则网络中随机孔道堵塞和均匀孔道堵塞对分子扩散的影响。     

广西向阳坪铀矿“打滑”地层绳索取心钻进存在问题与对策

通过绳索取心钻进金刚石钻头选型试验，介绍了广西资源县向阳坪铀矿区“打滑”地层中绳索取心钻进存在的问题及采取的技术措施。