基于虚拟激励法的变速行驶车辆振动分析

在虚拟激励法的基础上,建立了人车路垂向动力学模型和道路虚拟输入模型,推导了车辆非匀速行驶的时-空频率关系,得到了车辆非平稳响应的瞬时功率谱,应用Mathematic语言编制了四分之一人车模型的仿真程序,以简化模型为例,考察了变速车辆行驶的平顺性.数值仿真结果表明,虚拟激励法用于求解车辆振动响应,尤其是用于非平稳随机输入下的车辆振动分析,简便快捷,省时省力,能很好地反映汽车乘坐舒适性.     

基于S变换与PNN的电磁环境复杂度评估

针对复杂电磁环境定性分析和定量分级问题,提出基于广义S变换与PNN(概率神经网络)的电磁环境复杂度评估方法.应用广义S变换对电磁环境中受干扰的样本信号进行时频分析,同步提取时频域时域占用度,频域占用度和能量占用度评估参数,分析了各参数的物理意义,并给出了各评估参数的计算公式.同时增加频率重合度、调制格式相似度和背景噪声强度等评估参数,利用获取的参数训练PNN,并进行分类.仿真实验证明基于广义S变换与PNN的电磁环境复杂度评估方法在背景噪声大、训练样本数少的条件下能有效提取评估参数,并对电磁环境复杂度进行有效合理评估.     

4045铝合金热变形行为及其加工图

采用Gleeble-3500热模拟试验机对4045铝合金在变形速率为0.01~10 s-1，变形温度为300~450 ℃条件下进行等温热压缩实验，研究了该合金的热变形行为及其热加工特性.结果表明：4045铝合金热变形过程的流变行为可用双曲正弦模型来描述，其平均激活能为189.93 kJ/mol.基于动态材料模型(DMM)获得了4045铝合金的热加工图，并结合热加工图和金相显微组织分析得到了该合金在实验参数范围内较优的热加工工艺参数范围：加工温度为380~450℃，变形速率为0.1~0.3 s-1.     

基于概念设计的客车车身结构设计与优化系统

针对客车车身结构概念设计的特点，开发了客车车身结构概念设计与优化系统（简称BCD），建立了参数化的客车车身结构概念模型.以该模型为模板，实现了新客车车身结构概念几何模型的创建和车身尺寸参数调整，同时建立了车身系统的静态刚度分析、低阶模态分析、灵敏度计算和优化设计计算的自动化过程，对车身的结构性能和低阶模态进行了有效的预估.最后，本文使用该系统计算了某客车车身结构的刚度和低阶模态，并在保证车身质量降低的情况下实现了刚度和低阶模态的提高，有效的改善该车身结构性能，实现了车身轻量化，验证了BCD系统的有效性和可靠性.     

Field Emission Characterization of 1D-Nanostructural ZnO Grown at Low Temperature

Ondeu-ctdio rmse nhsaivoen aaltt rwaicdteed b aan gdr-egaatp d neaaln oosft uartctteunrtialon se bmeiccaounse-of their remarkable physical and chemical properties[1 ,2].Amongthose properties ,the highaspect ratio of these materi-als makes them genuine can…     

A Parallel Genetic Simulated Annealing Hybrid Algorithm for Task Scheduling

0 IntroductionGrid computingis a hot topic inthe current internet research,and a developing direction of the parallel and distributedprocess[1 ,2].Since the task scheduling in grid computing faces aNP-hard problem[3];it has drawn attention from many scholarsand become the focusinthe field of the current grid computing re-search.In recent years , two global random and opti mal algorithmhave been widelystudiedandappliedinthefield of the gridcompu-ting research: GA(Genetic Algorithm) and SA( …     

Merkle Tree Digital Signature and Trusted Computing Platform

0 IntroductionDigital signatureis a key technique to provide datainteg-rity andsource authenticationcapabilities to enhance da-ta trustworthiness in trusted computing platform. Most cur-rent digital signature schemes are based on complex mathe-matical problems , such as integer factoring, discrete log-arithm,and discrete logarithm on elliptic curves . The hard-ness of these underlying mathematical problems is really un-certain at present . Merkle treeis a method used for authenti-cation and di…     

Improvement of Identity-Based Threshold Proxy Signature Scheme with Known Signers

0 IntroductionIdentity-based (ID-based) cryptography[1]is rapidly emer-gingin recent years .The concept of the proxy signature scheme was first in-troduced by Mamboet al[2]in 1996 .The concept of thresholdproxy signature was proposed[3 ,4]. Apractical and secure (t,n) threshold proxy signature scheme should satisfy the secre-cy,the proxy protected,the unforgeability,the non-repudia-tion,the ti me constraint ,andthe known signers[5].In 2006 , Baoet al[6]proposed an ID-based thresholdproxy si…     

Fluorescence spectra and enzymatic property of hemoglobin as mimetic peroxidase

0　IntroductionHemoglobin(Hb)isthemajorhemeproteinofredbloodcells(RBCs)andisresponsibleforthetransportofoxygentothetissues.ThefunctionofHbdependsupontheabilityoffer rousironinthehemegrouptobindandreleaseoxygen .Despiteitsprincipalroleasanoxygen carrier,theHbmoleculepossessesdifferentenzymaticactivities[1 ] andamethodwasdevelopedforthedeterminationofHbbasedonitsenzymaticactivityfortheox idationofo phenylenediamine (OPDA)withH2 O2 asanoxi dant[2 ] .Hbasamimeticenzymeofperoxidase ,cancataly…     

基于ADAMS/ATV的履带装甲车辆托带轮分布方案优选

履带装甲车辆的履带与托带轮的垂向冲击是产生冲击噪音和导致履带疲劳与断裂的重要因素。基于ADAMS软件中的ATV模块对某型履带装甲车辆建立了动力学模型，针对各托带轮所受履带的垂向冲击力大小不均匀的问题，综合动力学仿真分析，优选托带轮的分布方式，改善其动力学性能。