汶川地震灾区泥石流启动机制及其动力学特征——以北川县五星沟为例

2008年5月12日,四川汶川发生8.0级特大地震,地震造成了大量山体滑坡、崩塌、泥石流等次生地质灾害,给北川县带来了严重的人员伤亡和财产损失。受降雨影响,位于北川县擂鼓镇的五星沟分别于2008年9月24日及2009年7月17日发生特大型泥石流,造成了五星沟沟内五星村、大田村和南竹村等多处居民点被冲毁,沟谷两侧房屋倒塌或被掩埋。根据已有资料,通过分析五星沟泥石流的分布和形成特征,从泥石流形成的物源条件和动力条件两方面探讨了该泥石流启动机制与物源转化机制,推算不同设计频率下泥石流的特征值,包括该泥石流的运动及动力特征。分析表明:五星沟大部分支沟属中频泥石流沟,发展阶段均属发展期;五星沟具备再次发生泥石流的基本条件,建议尽快对其实施应急治理。开展五星沟泥石流启动机制的研究,对于监测与治理汶川地震造成的次生泥石流灾害,具有指导意义。     

Peirce机织物几何结构模型的探讨

织物几何结构就是纱线在织物内部的屈曲状态,它影响织物的外观效应和物理机械性能,必须精确计算.在被普遍使用的Peirce机织物几何结构模型中,暗含如下假设:1织物中经纬纱屈曲波高无论怎样变化,其和均等于经纬纱理论直径之和乘以压扁系数;2同一浮长覆盖下的纱线中心在同一水平面上,屈曲波高仅与织物密度和织造缩率有关.从两个方面对此进行验证,一是以经典教材多块织物样品为例,用Peirce公式计算结果评估自身的精确性;二是用Nedgraphics纹织系统设计同一经纬密度的各种结构的机织物,在电子提花机上织造后利用Keyence 3D共聚焦显微镜对织物正反面进行非破坏性测量,得到不同浮长织物的屈曲波高并进行分析.结果表明,Peirce机织物的几何结构模型存在不足,需进一步改进.     

Experimental investigation on the stability of bride girder against tsunami forces

Bridges are the most useful part in the transportation network. Any disruption of the bridge structures may hamper the whole transportation system. In the last recent tsunamis, numerous number of bridges were structurally damaged by the tsunami waves. Lack of proper provisions of tsunami forces in the design guidelines also contributes to the augmentations of the damage level. Therefore, proper evaluation of the tsunami forces on the bridge girder should be introduced in the design promptly. In this study, laboratory experiments were carried out to reveal the damage mechanism of the bridge girder by assessing the exerted tsunami forces. Both broken and unbroken waves were considered for the analysis. The results showed that measured forces were larger for broken waves than those of unbroken waves. Maximum force of the broken waves was 4.59 times as large as the hydrostatic pressure. Also, waves reached the peak value more rapidly for larger wave heights than those of smaller ones. Additionally, a girder that is placed at a higher position is much vulnerable to tsunami hazard.     

Rate-compatible network LDPC codes

A rate-compatible puncturing algorithm for network LDPC codes is proposed to achieve the minimum error probability, and decoding error probability is derived. The algorithm for finding variable nodes to be deleted based on the tanner graph of network LDPC codes is proposed, which is aimed at minimizing the decoding error probability and optimizing the puncturing pattern. Simulation results illustrate that, at BER=10^-4, the proposed rate-compatible network LDPC codes have a coding gain of about 0.4dB compared with the codes obtained via the existing punctured methods.     

高精度小型无人机气压高度测量系统的设计

介绍了一种基于MPX4115传感器和C8051F352单片机的小型无人机高度测量系统的设计及实现过程,详细论述了系统软硬件的设计原理,对传感器性能进行了分析并利用压力校验仪对其压力、温度补偿系数进行修正,保证测量准确度;通过硬件设计增加抗干扰能力并设计软件滤波算法提高输出稳定性;对高度-气压公式进行了插值拟合,解决了单片机计算能力不足的问题,提高计算性能;该系统具有小型化、功耗低、结构简单、精度高,稳定性和抗干扰能力强等优点。     

空中无线电监测平台最佳工作高度探究

无线通信技术的快速发展使得无线电监测环境日益复杂,传统的无线电监测网很难满足日常无线电监测的需求,为了实现空中无线电全方位立体式的监测,实现覆盖范围内空中频率通信安全畅通,探究满足需求的最佳平台工作高度.在云南省昆明市呈贡大学城应用飞艇作为空中平台,搭载无线电监测设备,对发射的12个不同地点的监测信号进行信号强度的测试.飞艇飞行高度达到100m时,大部分监测信号能被监测得到,能满足无线电监测的日常需求.证明了建立云南省空中无线电监测的可行性,并得出了满足监测工作需求的最佳平台高度,为今后空中监测平台的部署提供了有力支撑.     

纺牵卷一体机牵伸辊上丝路调节方法的分析

分析了纺丝丝束在纺牵卷一体机双辊牵伸机上的丝路形状与牵伸辊直径、双牵伸辊的夹角、左牵伸辊的调节角度和入辊丝的分丝宽度的关系 ,并找到形成最佳丝路时的各辊最佳角度 ,可很快地调节丝路 ,不会产生大量废丝     

建筑工程测量中高差闭合差的计算与调整

在高程控制测量中，可以通过计算高差闭合差来检验观测成果的质量。而高差闭合差这一概念，在建筑工程测量的实际应用中容易混淆。文章从高差闭合差计算、调整和高程计算三个方面入手，给出了对高差闭合差理解的思路，以及在控制测量中高差闭合差平差的新方法。经实践验证，有益于工作效率的提高。     

Numerical simulation and comparison of electrical characteristics between uniaxial strained bulk and SOI FinFETs

In this paper, electrical characteristics of 25 nm strained fin-typed field effect transistors (FinFETs) with oxide-nitride-stacked-capping layer are numerically studied. The FinFETs are fabricated on two different wafers, one is bulk silicon and the other is silicon-on-insulator (SOI) substrate. A three-dimensional device simulation is performed by solving a set of density-gradient-hydrodynamic equations to study device performance including, such as the drain current characteristics (the I_D-V_G and I_D-V_D curves), the drain-induced barrier height lowering, and the subthreshold swing. Comparison between the strained bulk and SOI FinFETs shows that the strained bulk FinFET is promising for emerging multiple-gate nanodevice era according to the manufacturability point of view.     

基于机理与系统辩识法建模的电源噪声对无线电引信作用影响研究

采用机理法和系统辩识法两种方法对电源处理电路（集成稳压器）进行分析，重点探究了电源处理电路对电源噪声的响应与抑制能力，最后得出电源噪声对无线电引信的作用影响是，会使炸高提高，当噪声足够大时，会引起早炸．