Cr(CO)_n(n=1-5)与C_6 H_6相互作用的密度泛函研究

用密度泛函理论在B3LYP/LANL2DZ基组水平上对(η~x-C_6H_6)Cr(CO)_n(x=1-6;n=1-5)复合物体系的可能构型进行了自由优化及相互作用能的计算,研究了不同羰基数对复合物稳定性、苯和羰基铬相互作用的影响,并对苯和羰基铬相互作用进行了NBO分析。得到以下结论:(1)当n≤3时,苯与Cr(CO)_n以η~6配位;当n≥4时,苯与Cr(CO)_n以η~2配位;(2)最稳定复合物中随羰基数的增加Cr-C_(benzene)平均键长增长,最大二面角H-C-C-H偏离碳环的角度随复合物对称性降低而逐渐增大;(3)当n为奇数时,复合物相互作用主要表现为苯C-C键的π轨道和Cr-CO键的σ反键轨道;当n为偶数时,复合物相互作用主要表现为苯C-C键的π轨道或π~*轨道与Cr的孤对电子轨道;(4)复合物羰基数越多,最稳定复合物的相互作用能数值越大,稳定性越小。     

3D-freehand-pose initialization based on operator’s cognitive behavioral models

Tracking, recognition and interaction based on 3D freehand are a part of our virtual assembly system, in which monocular camera is used to input online freehand videos and the hand pose tracker requires a reliable initial pose in the first frame. A novel approach to initializing 3D pose and position of freehand is put forward in this paper visualization of 3D hand model and modeling the operators’ cognitive behaviors. Our approach is composed of three phases: hand posture recognition, coarse-tuning and fine-tuning. The operator moves his/her hand onto the to meet the needs of our virtual assembly system. The main contribution of this paper is that the three core techniques are for the first time integrated together, including human–computer interaction (HCI) in the process of initializing, projection of the 3D hand model in the period of coarse-tuning time. Then, the computer repeatedly fine-tunes the 3D hand model until the projection of the 3D hand model is completely superimposed onto the operator’s hand image. We focus on exploring and modeling cognitive behavior of operator’s hand upon which we design our initialization algorithm. Our research shows that cognitive behavioral models are not only beneficial to reducing cognitive loads for operators, because it makes the computers cater for the changes of the operators’ hand poses, but also helpful to address high dimensionality of articulated 3D hand model. Our experimental results also show that the approach presented in this paper is easier, more pleasurable and satisfactory experience for the operators. Our initialization system has successfully been applied to our 3D freehand tracking system and a simulation virtual assembly system.     

A fully geometric approach for developable cloth deformation simulation

We present a new method for simulation of inextensible cloth subjected to a conservative force (e.g., the gravity) and collision-free constraint. Traditional algorithms for cloth simulation are all physically-based in which cloth is treated as an elastic material with some stiffness coefficient(s). These algorithms break down ultimately if one tries to set this stiffness coefficient to infinite which corresponds to inextensible cloth. The crux of the method is an algorithm for interpolating a given set of arbitrary points or space curves by a smooth developable mesh surface. We formulate this interpolation problem as a mesh deformation process that transforms an initial developable mesh surface, e.g., a planar figure, to a final mesh surface that interpolates the given points (called anchor points). During the deformation process, all the triangle elements in the intermediate meshes are kept isometric to their initial shapes, while the potential energy due to the conservative force is reduced gradually. The collision problem is resolved by introducing dynamic anchor points owing to the collision during the deformation. Notwithstanding its simplicity, the proposed method has shown some promising efficacy for simulation of inextensible cloth.     

BASE: A bacteria foraging algorithm for cell formation with sequence data

A cellular manufacturing system (CMS) is considered an efficient production strategy for batch type production. A CMS relies on the principle of grouping machines into machine cells and grouping parts into part families on the basis of pertinent similarity measures. The bacteria foraging algorithm (BFA) is a newly developed computation technique extracted from the social foraging behavior of Escherichia coli (E. coli) bacteria. Ever since Kevin M. Passino invented the BFA, one of the main challenges has been employment of the algorithm to problem areas other than those for which the algorithm was proposed. This research work studies the first applications of this emerging novel optimization algorithm to the cell formation (CF) problem considering the operation sequence. In addition, a newly developed BFA-based optimization algorithm for CF based on operation sequences is discussed. In this paper, an attempt is made to solve the CF problem, while taking into consideration the number of voids in the cells and the number of inter-cell travels based on operational sequences of the parts visited by the machines. The BFA is suggested to create machine cells and part families. The performance of the proposed algorithm is compared with that of a number of algorithms that are most commonly used and reported in the corresponding scientific literature, such as the CASE clustering algorithm for sequence data, the ACCORD bicriterion clustering algorithm and modified ART1, and using a defined performance measure known as group technology efficiency and bond efficiency. The results show better performance of the proposed algorithm.     

KISTCM: knowledge discovery system for traditional Chinese medicine

Objective: Traditional Chinese Medicine (TCM) provides an alternative method for achieving and maintaining good health. Due to the increasing prevalence of TCM and the large volume of TCM data accumulated though thousands of years, there is an urgent need to efficiently and effectively explore this information and its hidden rules with knowledge discovery in database (KDD) techniques. This paper describes the design and development of a knowledge discovery system for TCM as well as the newly proposed KDD techniques integrated in this system.     

2009多国仪器仪表展览会流量仪表评估

简要介绍了2009年多国仪器仪表展览会(MICONEX2009)上流量仪表参展商概况、12大类参展流量仪表所占比例,并分析评述了展品及其亮点,如新流量测最原理的激光流量计,向小流量低流速方向延伸的超声流量计、超声热黾表和超声水表,能测量液体的MEMS(微机电系统)制的热式流量计,可代替机械式的MEMS家用/商用燃气表,高阶椭圆齿轮流量计等.     

基于窗函数的FIR数字滤波器的优化及Matlab实现

窗函数法是设计数字滤波器的一种方法。简要介绍了如何利用窗函数进行FIR数字滤波器的设计,以及分析各种不同窗形式对滤波器性能的影响。最后运用Matlab进行仿真比较。     

网络攻击与防范研究

随着信息时代的到来,越来越多的企业或个人逐步意识到信息安全防护的重要性。计算机网络、数据通信、电子商务、办公自动化等领域需要解决信息安全问题。如何保护企业或个人的信息系统免遭非法入侵？对目前计算机网络存在的网络攻击方法进行了分析,从发现正确的目标到执行攻击,并提出相应的防范措施。     

社保网络信息安全防护

本文针对各种威胁社保网络安全的多种因素,进行有的放矢地构建相应策略,综合立体地进行网络安全防护,构建了一个多方面考虑的安全网络,这样社保部门在保护计算机网络设备安全和计算机网络系统安全的同时也保护了数据的安全,为构建和谐社会贡献力量。     

Quarter Load Threshold (QLT) flow control for wormhole switching in mesh-based Network-on-Chip

The fact that latency increases abruptly once the on-chip network is saturated indicates that it is necessary to devise an effective flow control strategy. Through tracing the status of the network buffer space we found that the payload of the on-chip network cannot get beyond an upper bound to avoid vicious congestion. Specifically, quarter of the total network buffer space is such a threshold, which is termed Quarter Load Threshold (QLT). Based on this fact we present the Quarter Load Threshold (QLT) flow control strategy. The performance of the proposed strategy is evaluated by the open source simulator Noxim [Noxim: Network-on-Chip Simulator, http://sourceforge.net/projects/noxim, 2008]. Simulation results show that the on-chip network runs smoothly and no serious congestion is encountered any more.