多目标满意优化在数字滤波器设计中的应用

提出了一种应用多目标满意优化进行数字滤波器优化设计的方法，给出了计算模型和算法，该方法以满意度函数反映设计者对性能指标的评价，更符合实际要求，应用该方法对有限冲击响应数字滤波器的过滤带采样点的取值进行优化设计，仿真结果表明了该方法的有效性和实用性。     

新疆叶尔羌河宽浅变迁河段股流形成机理探讨

针对新疆叶尔羌河宽浅变迁河段特有的水流泥沙特性,运用现场调查、理论分析及动床试验模型相结合的方法,对麦盖提大桥桥位宽浅变迁河段的股流形成机理进行了初步探讨,得出了叶尔羌河宽浅变迁河段股流的形成受到上游来流量变化、水流横向环流、床沙抗冲特性等多种因素的共同影响,并对此类河段股流的特征进行了描述。     

基于宽带接入服务器的分布式安全审计系统

用宽带接入服务器(BAS)作为分布式审计代理实现城域网(MAN)上的主动式安全审计系统．提出一种新的硬件包过滤机制(HPF)以适合系统的需要．BAS上的路由转发机制从“一次路由，多次交换”改为“一次审计，多次通过”．采用基于时间推理机的算法完成对UDP访问的审计．系统在试验网络中进行了测试，显示了很好的审计处理性能。     

Radar Emitter Signal Recognition Based on Complexity Features

Intra-pulse characteristics of different radar emitter signals reflect on signal waveform by way of changing frequency, phase and amplitude. A novel approach was proposed to extract complexity features of radar emitter signals in a wide range of signal-to-noise ratio ( SNR), and radial basis probability neural network (RBPNN) was used to recognize different radar emitter signals. Complexity features, including Lempel-Ziv complexity (LZC) and correlation dimension (CD), can measure the complexity and irregularity of signals, which mirrors the intra-pulse modulation laws of radar emitter signals. In an experiment, LZC and CD features of 10 typical radar emitter signals were extracted and RBPNN was applied to identify the 10 radar emitter signals. Simulation results show that the proposed approach is effective and has good application values because average accurate recognition rate is high when SNR varies in a wide range.     

Distributed Broker-Agent Architecture for Multimedia Communications Traversing NAT／Firewall in NGN

The forthcoming Next Generation Network (NGN) is an all IP network. Multimedia communications over IP networks are a type of bundled session communications, which cannot directly traverse Network Address Translations (NATs) and firewalls even in NGN. To solve the problem that the existing traversal methods are not suitable for service providers to set up a real system in NGN,a Distributed Broker-agent Architecture (DBA) is addressed. DBA is secure and realizable for service providers and enterprises because it is easy to set up and does not need to upgrade the existing devices like Firewalls, NATs or endpoint devices of subscribers.DBA is composed of two-layer distributed agents, the server proxies and the client agents, in which all multimedia communications use shared tunnels to carry signaling messages and media data between broker-agents, and the call signaling is encrypted over Security Socket Layer (SSL) to guarantee the security of calling. Moreover, the function model and multiplexed connection messages format of DBA are designed, which lays a basis for the protocol in the future NGN. In addition, a simple implementation based on H.323 verifyies the main function of traversing firewalls and NATs.     

基于频率和形状特征的脉冲重复间隔调制识别

根据雷达信号脉冲序列的特点，从雷达脉冲信号中提取频率特征和形状特征，构成二维特征向量，并用支持向量机设计多类别分类器，实现雷达信号PRI调制信号的自动识别．实验结果表明，对特征向量进行大幅度降维（从64维降到2维）后，既简化了分类器，又保持或提高了识别率和抗噪声性能．与原特征向量相比，对无噪样本的误识率从0．15％～0．25％降低到0．00％，对有噪样本的误识率从0．40％～1．30％降低到0．15％～0．93％．     

恶意主机上Mobile Agent安全解决方案

根据非对称加密原理提出了恶意主机上Mobile Agents（MA）的安全解决方案。在该方案中，只有得到许可的主机才能执行MA的代码，交换的数据也要求加密。当MA返回源主机后可根据MA执行过程中的信息判断是否有目标主机对其有恶意行为。分析了恶意主机上MA所受到的安全威胁，并用所提出的方案逐一分析解决了MA所受到的安全威胁。     

川维厂取水口泥沙淤积研究

采用二维水流泥沙数学模型建立贴体正交网格,对川维厂取水口河段在三峡成库后进行不同流量工况下的流场计算,运用一个水文系列年循环计算出成库后该河段的悬移质淤积过程、淤积量、淤积分布.分析计算结果得出:成库后工程河段断面流速减少;取水口位置水势未变,水面依然存在横比降;悬移质主要在两岸的回流区和缓流区成累计性淤积,淤积速率基本一致.着重分析了取水口位置的水流条件变化、淤积后的河演变化对正常取水的影响.     

基于Simulink的列车横向半主动悬挂系统建模与仿真

利用Simulink软件建立17个自由度的列车横向半主动悬挂系统模型,并设计了PID控制器。以美国六级轨道谱为输入,利用Matlab7.0进行仿真。结果表明,摇头振动是影响列车横向平稳性的主要因素,与被动悬挂相比,半主动悬挂PID控制效果明显好于被动悬挂。     

2万t组合列车中部机车载荷谱试验研究

以120 km/h速度等级8轴货运电力机车为研究对象,在大秦线测试了其牵引2万t重载组合列车时的车钩纵向载荷、牵引装置纵向载荷、主要承载件动应力的时间历程,根据雨流计数法获得了相应的载荷谱(应力谱),可用于类似结构大功率机车车体、车钩及牵引装置的结构可靠性设计,并可用于作为相关部件的可靠性试验评定。