Incoherent scatter spectra due to HF heating in the low ionosphere region

The electron velocity distribution function and the incoherent scatter spectra during ionospheric heating in low ionosphere region are presented with consideration of the elastic collision between electrons and neural particles and the excitation of rotation energy level. The effects of pump frequency and electric fields on the spectra are discussed. With the increase of electric field, the non-Maxwellian feature is enhanced, and with the increase of heating frequency, the non-Maxwellian feature is weakened. The non-Maxwellian factor will bring a large error in ionosphere parameters, which must be considered in the inversion. Supported by the National Natural Science Foundation of China (Grant No. 40310223), the National Key Laboratory of Electromagnetic Environment (LEME), and National Key Technologies R&D Program of China (Grant No. 2006BAB18B06)     

Emergency aero-photo survey after the 5.12 Wenchuan Earthquake,China

After the 5.12 Wenchuan Earthquake which took place on May 12, 2008, aerial remote sensing has rapidly covered all the influence sites of the earthquake, emergency aero-photo interpretation has revealed the disaster distribution limitation, and captured the information of location, dimension of the destroyed houses, roads and other structures, blocked rivers, etc, which provided destroying conditions of the time for rescuing lives, rebuilding traffic lines and estimating disaster situation. The further interpretation and analysis indicate that large scale second growth geological disasters mainly distribute in the distance of 0–300 km and 45°–50° orientation from the epicenter. About 137 latent large-scale landslides and debris-flows will occur in this rain season and coming several years, so how to avoid current geological disasters as well as the latent large disasters should be considered in making rebuilding and developing plan.     

Safety evaluation and the static-dynamic coupling analysis of counter-arched slab in plunge pool

The stability of plunge pool slab of drainage structure is crucial to energy dissipation, but the working conditions of counter-arched slab are very complex and its stress procedure is considerably nonlinear and coupling. Therefore, a nonlinear static and dynamic coupling method to analyze the counter-arched slab configuration is put forward, which can reflect the coupling of dynamic loads, slab, anchor bars, groundwork and abutment as well as the dynamic procedure of instability. Various nonlinear factors and static-dynamic coupling are taken into consideration, and the working conditions, stress mechanism, dynamic instability procedure and influential instability factors are revealed. The proposed method thus provides a comprehensive safety evaluation method of plunge pool, which further provides an important theoretical basis for engineering design of counter-arched slab in plunge pool. Supported by the National Science Fund for Distinguished Young Scholars (Grant No. 50725929) and the National Natural Science Foundation of China (Grant Nos. 50539060, 50679052, 50779044)     

移动商务竞价行为的精炼贝叶斯纳什均衡研究

研究了移动商务环境下企业竞价决策行为的贝叶斯纳什均衡问题.企业间信息不对称导致价格博弈成为决定最终购买的重要因素.将移动商务下企业产品竞价过程视为一个信息不完全条件下的动态博弈过程,首先分析了企业购买行为中所涉及的基本信息及其抽象表示,对进行博弈分析的基本假设进行定义,然后引入自然人对目标企业收益不确定性进行贝叶斯先验概率设定,在此基础上对购买竞价过程进行精炼贝叶斯纳什均衡解研究,从而得到移动商务竞价行为的博弈均衡解.     

一种简化的CA认证系统

针对网络安全问题,在对PKI机制和SSL技术深入研究之后,从节省成本、便于维护的角度出发,设计了一套简化的CA认证系统,实现了安全连接建立前通信双方身份的识别,然后采用数据加密传输,为用户数据通信提供安全保证.     

基于STPN的项目进度规划

通过将网络计划图映射为Petri网形式, 在Petri网上求解完成工序所需时间不确定时的网络时间与关键路线, 给出相对于传统的计划评审法, 该方法工序时间可以为任意分布, 且较容易通过多次模拟得出最优解的经验分布, 与PERT仅仅给出数学期望与方差相比结果更丰富.最后探讨了基于STPN的时间一资源优化求解算法, 其计算时间仅为O(nk), 其中n为网络节点数, k为网络结点之间的连接数, 其算法比线性规划方法更有效率.     

汽车拉杆总成试验台计算机测控系统研究

以汽车转向拉杆球头销疲劳试验台为应用背景,阐述了如何采用VB6.0编程语言实现西门子S7-200系列PLC与上位计算机的串行通信,完成了PLC与计算机之间的数据交换,为最终实现计算机对PLC所连接的试验台工作状态的实时监控提供了通信支持.     

青县电子机箱产业集群核心竞争力评价

根据核心竞争力理论,运用层次分析法,构建了对产业集群的核心竞争力评价体系,并用此方法对青县的的电子机箱产业进行了实证分析.研究结果表明青县电子机箱行业的核心竞争力不强,其中资源整合与控制能力,技术创新能力、组织管理能力、人力资源竞争力和企业文化聚合力较弱、在此基础上提出了相应的政策建议.     

CVSD语音编解码的DSP实现

连续斜率可变增量调制(CVSD)语音编码简单且具有良好的抗信道误码能力,擅长处理丢失和被损坏的语音采样,较其他编码方法语音效果更清晰,可靠性更高,降低带宽的同时保证了语音质量.利用DSP芯片研制开发基于语音压缩编码技术的语音产品已经成为一大研究热点.选用TMS320VC5509芯片作为硬件平台,用C语言实现了CVSD语音编解码,能较好实时实现语音编解码.     

差动放大电路共模干扰抑制能力的研究

电磁流量计输出的流速信号非常微弱,且常叠加共模干扰,经信号调理电路放大后,会导致信噪比很低,甚至淹没有用信号．针对这问题提出了利用前置放大电路有效抑制共模干扰,对其进行定性、定量分析,给出实际可行的提高差动放大电路输入阻抗的设计,并进行分析、推导和对比计算,证明其可以很大限度抑制共模干扰,提高测量准确度．