A catheter withdrawing apparatus for clinical urethral pressure profile studies

An apparatus for withdrawing a urethral catheter at a constant speed is described. The motor and the puller assembly are separate components so that the puller assembly can be autoclaved. By matching pulling speed to recorder chart speed a reproducible representation of urethral length can be obtained without using a displacement transducer. The apparatus has been used clinically for measuring urethral pressure profiles.     

一种改进的基于正区域的决策树算法

首先分析了基于正区域、基于粗糙边界和基于依赖度的属性选择标准的关系,并证明了这三种属性选择标准彼此等价.然后以正区域的属性选择标准为代表,分析了、基于正区域的决策树生成算法的优点和不足.针对这些不足,给出了一种新的属性选择标准,即基于伴随正区域的属性选择标准.用新的属性选择标准生成的决策树一般具有叶子数目较少,叶子的平均深度也较小,且叶子具有较强的泛化能力.最后,用一实例说明了新的属性选择标准的优越性.     

低速无线个人区域网802．15．4的安全研究

短距离无线通信技术近年来成为通信领域热点,其主要特征是低功耗、低成本和低数据率,可广泛应用于军事、工业控制、精准农业及医学等领域的无线传感器网络构建,将会在未来的后PC即普适计算时代发挥重要作用.同时,由于其开放传输信道和\"三低\"特性,安全性成为保证短距无线通信网络健壮稳定运行的关键\"基石\".针对低速无线个人区域网(LR-WPAN)802.15.4,详细分析其安全架构,根据最高安全级别组件AEs-CCM的底层加密算法AES和泛型CCM模式,结合安全帧格式,提出了一种AES-CCM实施的输入分组模型,并进行时间性能对比实验.针对LR-WPAN可能存在的攻击和802.15.4潜在的安全问题,提出相应的改进措施.     

Simulation of spatially-heterogeneous oxygen precipitation in silicon with allowance for internal mechanical stresses

A new model of the kinetics of oxygen precipitation in silicon, which allows for the effect of internal mechanical stresses that arise at the boundaries of precipitation particles on the speed of oxygen transport and silicon oxidation reactions, is developed based on an approach previously proposed by authors. Temporal variations of the spatial distribution of oxygen in a silicon plate are calculated under conditions of the formation of precipitation particles. Dependences of the width of a defect-free zone formed in a plate on the time and temperature of the annealing are obtained. This is an important characteristic of the formation of an internal getter in carriers. The allowance for internal mechanical stresses is shown to result in decreasing the rate of the widening of a defect-free zone, which agrees with the experiment data. The results can be used to optimize the formation of an internal getter.     

Application of Computer Algebra Methods to Investigate the Dynamics of the System of Two Connected Bodies Moving along a Circular Orbit

Programming and Computer Software - Computer algebra methods are used to investigate properties of a nonlinear algebraic system that determines the equilibrium orientations for a system of two...     

Application of Symbolic Computation Methods for Investigation of Stationary Motions of an Axisymmetric Satellite

With the help of computer algebra methods properties of the algebraic system that determines stationary motions of an axisymmetric satellite moving along a circular orbit subject to gravitational and active damping moments are investigated. The main attention is paid to the study of the conditions for the existence of stationary satellite motions. Computer algebra methods based on the algorithm for the construction of Gröbner bases are applied to reduce the satellite stationary motion system of six algebraic equations in six variables to a single algebraic equation in one variable that determines all stationary motions of the satellite. A classification of domains with equal numbers of stationary solutions is carried out using algebraic methods for constructing discriminant hypersurfaces. The effectiveness of various algorithms for constructing Gröbner bases for the solution of the problem under consideration was compared.