基于时空处理的频率与二维DOA联合估计算法

提出了一种适用于任意阵列的频率与二维DOA联合估计算法.该算法同时利用空域采样与时域采样构造二维时空矩阵,基于2D-ESPRIT方法进行二维参数估计,仅需3个校准阵元就可通过M个阵元估计出M个独立信源的载波频率、方向角和仰角,无需二维谱峰搜索,计算量较小.仿真实验验证了算法的有效性.     

MIMO-OFDM系统的自适应多用户分集及性能分析

 本文建立基于随机波束成形和自适应调制的MIMO-OFDM系统的自适应多用户分集系统模型,提出随机波束成形QR接收机的自适应多用户分集资源分配算法及其简化算法,推导在最大化系统吞吐量条件下系统的误码性能.仿真结果表明该算法在用户数很小时使系统性能收敛到特征波束成形系统的性能;当用户数增多时,采用天线分配算法的多用户分集系统能获得比特征波束成形系统更好的性能;将自适应编码调制技术运用到多用户分集系统来提高系统的实际吞吐量和误码性能.     

鞍形屋盖平均风压分布特性的数值模拟研究

基于Reynolds时均N-S方程和RSM模型对鞍形屋盖的平均风压分布进行了数值模拟,采用有限体积法对控制微分方程进行离散,并采用SIMPLE压力校正算法来实现非线性方程的迭代求解。数值模拟结果与风洞试验结果进行了对比分析,两者吻合较好,在此基础上系统研究了风向角、跨高比、矢跨比、地面粗糙度、风速等因素对屋面风压分布的影响,探讨了结构周围流场的绕流特性。最后根据屋面的结构形式及风压分布特点将鞍形屋面分成12个区,给出了不同风向角下的分区风载体型系数以供工程设计的参考。     

Interactive navigation system in smart phone with vibration feedback

The traffic congestion has become an urgent problem to be solved, which appears in the domestic and foreign large and medium-sized cities. Intelligent transportation is one of the important applications of ubiquitous computing. And it''s an important way to ease the traffic congestion of the city. Intelligent navigation system is an important embodiment of intelligent transportation. So far, there have been many kinds of traditional vehicle navigation systems. But when they are in use, drivers will pay extra attention to get the path information through the visual and auditory cues.It''s dangerous for drivers when they drive. At the same time, with the development of science and technology, mobile navigation system has been widely used. The mobile navigation system is a comprehensive system which relates to the field of mobile communication and GPS. The objective of this paper is to develop a smart phone and interaction navigation system based on the feedback of vibration and micro programmed control unit (MCU) control system. When drivers are in the driving process, the new navigation system can avoid the same sense of multiple tasks, which makes each sensory focus on only one independent task. Through the analysis, the system is demonstrated to improve the driving safety.     

多用户MIMO-OFDM系统的子信道可变速率算法

联合考虑随机波束成形和自适应调制建立了MIMO-OFDM系统的自适应多用户分集系统模型,提出了随机波束成形QR接收机的子信道可变速率算法,推导了在最小化系统误码率情况下系统的误码性能。仿真结果表明,该算法在用户数很小时使系统性能收敛到特征波束成形系统的性能;当用户数增多时,采用天线分配算法的多用户分集系统能获得比特征波束成形系统更好的性能;将自适应编码调制技术运用到多用户分集系统,从而提高系统的实际吞吐量和误码性能。     

中、美、加、欧屋面雪荷载规范对比

陈述了我国规范与美国、加拿大和欧盟规范在雪荷载取值方面的差异.结果表明：我国规范的雪荷载计算公式过于简单,不能充分考虑各种相关因素对雪荷载的影响;我国规范规定的屋面雪荷载临界坡度在4本规范中最小;在双坡、拱形和高低屋面中,我国规范的雪荷载剖面与国外规范差异较大;最后给出对我国规范雪荷载取值规定的一些初步修改建议,为我国...     

Multi-objective optimization of membrane structures based on Pareto Genetic Algorithm

A multi-objective optimization method based on Pareto Genetic Algorithm is presented for shape design of membrane structures from a structural view point.Several non-dimensional variables are defined as optimization variables,which are decision factors of shapes of membrane structures.Three objectives are proposed including maximization of stiffness,maximum uniformity of stress and minimum reaction under external loads.Pareto Multi-objective Genetic Algorithm is introduced to solve the Pareto solutions.Consequently,the dependence of the optimality upon the optimization variables is derived to provide guidelines on how to determine design parameters.Moreover,several examples illustrate the proposed methods and applications.The study shows that the multi-objective optimization method in this paper is feasible and efficient for membrane structures;the research on Pareto solutions can provide explicit and useful guidelines for shape design of membrane structures.     

基于分层贝叶斯网络的车辆发动机系统电磁脉冲敏感度评估

提出一种基于分层贝叶斯网络(HBN)的车辆发动机系统电磁脉冲(EMP)敏感度评估方法,从概率角度考虑电磁干扰源位置、极化角度、部件敏感度等参量的随机性,估计发动机系统在强电磁脉冲作用下的失效概率。该方法利用事件树分析(ETA)对电磁脉冲传播过程建模,确定系统周围电磁环境的风险概率,运用电磁拓扑(EMT)分析发动机系统电磁耦合途径。考虑同层单元失效的相关性,以分层贝叶斯网络为框架融合事件树和电磁拓扑理论建立发动机系统电磁脉冲敏感度评估模型,并推导了部件级至系统级的失效概率计算公式。最后以高空核电磁脉冲环境为例,说明了某型号发动机电磁脉冲敏感度评估模型的参数获取方法和模型计算过程,并以超宽带高功率微波为例,进一步说明了本文评估模型的适用性。     

基于等效线性地基的某工业厂房抗震分析

以某生命线工程工业厂房为例,采用等效线性化方法近似考虑地基的非线性特性进行厂房抗震分析,并将计算得到的楼层反应谱作为对比参数,与线性地基假定条件下抗震分析结果进行对比,结果表明:对于剪切波速较低的厂址(剪切波速小于400m/s),线性地基假定条件下厂房地震响应明显大于等效线性地基下的结果,而当地基剪切波速较高时(剪切波速约为1 100m/s),两者计算结果相近,分析结论可为今后建构筑物抗震设计提供参考。     

衰减标准装置建标过程中相关的不确定度评定

衰减是无线电计量的重要参数,建立衰减标准装置,保证衰减的量值可靠传递,是无线电计量的一项重要任务。本文介绍了使用测量接收机作为衰减标准装置的衰减量测量方法,对衰减标准装置的不确定度进行了评定。考虑失配分量的影响,分别评定了固定和可变衰减器的衰减量测量结果的不确定度。