全CFRP筋混凝土柱低周反复荷载试验研究

考虑轴压比、剪跨比和配箍形式的影响,对6根全CFRP筋混凝土柱进行低周反复荷载试验,通过分析滞回曲线、骨架曲线、位移延性系数和耗能能力等特征,研究CFRP筋混凝土柱的抗震性能。试验结果表明:CFRP筋混凝土柱具有较强承载能力和变形能力;轴压比和剪跨比是影响试件抗震性能的主要因素,轴压比越小,试件的变形和耗能能力越强,刚度退化越平缓,剪跨比越大,试件的变形能力越强;通用屈服弯矩法计算得到的延性系数能够较好反映CFRP筋混凝土柱的延性,轴压比越小、剪跨比越大,试件的延性越好;新型螺旋式矩形箍筋在试件延性及耗能方面表现良好,可以应用于工程实际。     

坚定不移走中国特色社会主义政治发展道路——学习胡锦涛总书记“七一”重要讲话体会

胡锦涛总书记在“七一”重要讲话中对坚定不移走中国特色社会主义政治发展道路进行了科学阐释。这既是对90年来我们党领导人民建设社会主义民主政治实践经验的科学总结,也是对未来我国社会主义政治建设的战略部署。中国特色社会主义民主政治发展道路,以党的领导、人民当家作主和依法治国有机统一为本质特征,具有严谨的制度架构、鲜明的特点和巨大的优势,是历史和人民的选择。在新的历史时期,坚持走中国特色社会主义政治发展道路,必须立足我国国情,使之越走越实;积极稳妥地推进政治体制改革,使之越走越宽;大胆吸收和借鉴人类文明成果,使之越走越活;不断推进民主政治的制度化、规范化、程序化,使之越走越稳。     

武警院校教务工作适应特色办学对策研究

在当前武警院校“深化教学改革,实施特色办学”的大趋势下,院校教务部门应充分发挥谋划作用,认真研究特色办学的总体思路;充分发挥指导作用,科学探索特色办学的实现途径;充分发挥管控作用,积极创造特色办学的有利条件;充分发挥协调作用,科学统筹特色办学的各种关系。     

Signal‐to‐interference‐plus‐noise ratio estimation for wireless communication systems: Methods and analysis

The Signal‐to‐Interference‐plus‐Noise Ratio (SINR) is an important metric of wireless communication link quality. SINR estimates have several important applications. These include optimizing the transmit power level for a target quality of service, assisting with handoff decisions and dynamically adapting the data rate for wireless Internet applications. Accurate SINR estimation provides for both a more efficient system and a higher user‐perceived quality of service. In this paper, we develop new SINR estimators and compare their mean squared error (MSE) performance. We show that our new estimators dominate estimators that have previously appeared in the literature with respect to MSE. The sequence of transmitted bits in wireless communication systems consists of both pilot bits (which are known both to the transmitter and receiver) and user bits (which are known only by the transmitter). The SINR estimators we consider alternatively depend exclusively on pilot bits, exclusively on user bits, or simultaneously use both pilot and user bits. In addition, we consider estimators that utilize smoothing and feedback mechanisms. Smoothed estimators are motivated by the fact that the interference component of the SINR changes relatively slowly with time, typically with the addition or departure of a user to the system. Feedback estimators are motivated by the fact that receivers typically decode bits correctly with a very high probability, and therefore user bits can be thought of as quasipilot bits. For each estimator discussed, we derive an exact or approximate formula for its MSE. Satterthwaite approximations, noncentral F distributions (singly and doubly) and distribution theory of quadratic forms are the key statistical tools used in developing the MSE formulas. In the case of approximate MSE formulas, we validate their accuracy using simulation techniques. The approximate MSE formulas, of interest in their own right for comparing the quality of the estimators, are also used for optimally combining estimators. In particular, we derive optimal weights for linearly combining an estimator based on pilot bits with an estimator based on user bits. The optimal weights depend on the MSE of the two estimators being combined, and thus the accurate approximate MSE formulas can conveniently be used. The optimal weights also depend on the unknown SINR, and therefore need to be estimated in order to construct a useable combined estimator. The impact on the MSE of the combined estimator due to estimating the weights is examined. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004     

超声速型面可控喷管设计方法

提出了基于B-Spline曲线和特征线方法的超声速型面可控喷管设计方法,通过设置喷管轴向马赫数分布可以灵活地调整喷管的型面形状。数值验证结果表明,该方法不仅可以设计出高品质的喷管出口流场,而且能够实现喷管型面的灵活调整,可以获得长度与最短长度喷管一致,但流场品质更优的喷管。     

联合编队作战行动方案建模

研究联合编队的作战行动方案问题,首先需要建立合理的任务模型。在基本作战样式基础上,针对联合编队任务特点,设计了一种联合编队作战行动方案的建模方法。该模型包含对海攻击和对空防御等5种基本作战样式,结合规划和调度两方面的特点,提供了资源和系统状态的描述机制。实例证明建模方案不仅具有可行性,而且丰富了作战行动方案的建模理论,对联合编队作战系统的研究、决策和建设具有一定的参考价值。     

几种排水型高性能船阻力性能对比研究

采用阻力理论计算方法,以高速圆舭艇的阻力性能为基准,对高速圆舭艇、深V型船、穿浪双体船以及高速三体船的阻力性能进行了对比研究,对比较结果进行了分析,给出了各船型的最适用航速范围.     

挠性航天器变幅值输入成形姿态机动策略

针对变参数挠性航天器的姿态机动问题,在变幅值零振动成形器的基础上,提出了鲁棒性较强的变幅值零振动和零微分成形器设计方法,设计了鲁棒姿态机动策略.该机动策略的控制目标是,将航天器机动到期望状态的同时,消除挠性结构的残余振动.以含转动挠性太阳翼的航天器进行三轴姿态机动为例,进行数值仿真.仿真结果表明,该机动策略对挠性结构频...     

一种新的装备配置优化模型

传统的装备配置优化问题一般采用确定性的数学规划方法解决,难以满足高技术条件下现代战争中需要对大量随机现象和模糊现象进行精确定量分析的实际要求。在分析了高技术条件下装备配置问题一般特性的基础上,根据机会约束规划和模糊机会约束规划的思想,提出了一种新的建立装备配置优化模型的思路和方法,并给出了基于随机模拟的遗传算法的实值算例,算例结果与实际情况基本相符,反映了模型的科学性与实用性。     

加肋凹锥-环-柱结合壳结构参数分析

采用分区样条等参元法,分析了加肋凹锥 环 柱结合壳的应力和稳定性特点,研究了各项结构参数变化对结合壳应力和稳定性的影响,认为加肋凹锥 环 柱结合壳能有效降低锥柱结合部的纵向弯曲应力,但对于降低环向应力效果有限,建议在环壳段中部增加一档肋骨;半锥角的凹结合壳越大,嵌入环壳段的优势越明显;增大环壳与柱壳半径比可以有效降低环壳段中部的纵向弯曲应力.