Effects of the configuration of a baffle–avalanche wall system on rock avalanches in Tibet Zhangmu: discrete element analysis

Rock avalanches with a high mobility and kinetic energy pose a potential geological risk to surrounding buildings. Baffles and avalanche walls are effective ways to protect these buildings. However, the primary focus of previous studies has been on baffles or avalanche walls alone, and there have been very few studies investigating the effectiveness of a combination of baffles and avalanche walls as a countermeasure against rock avalanches. In addition, previous studies on lab-scale tests and numerical analyses often did not take the actual topography effects into consideration. In this study we adopted a numerical simulation approach based on an actual project in the town of Zhangmu, Tibet, with the aim to investigate the effect of different configurations of a combined baffle–avalanche wall system on impeding the kinetic energy of rock avalanches. A series of numerical analyses with discrete element methods (DEM) were conducted. First, the effect of three different pile groups on the reduction of the effect of the rock avalanche was studied using the numerical modeling study. Secondly, the influence of the size of the retaining wall on the maximum impact force of the rock avalanche was studied. Finally, a DEM modeling study on the energy dissipation capacity of the baffle–avalanche wall system was conducted. The results demonstrate that an arrangement of different baffle–avalanche wall systems will produce different results in terms of dissipating the energy of rock avalanches: when the wall is long enough to block all rock masses, enhancing baffle density will decrease the maximum impact force exerted on the avalanche wall; however, if the wall is just long enough to protect the target region, reducing baffle density will decrease the maximum impact force exerted on the avalanche wall. The results of this study are significant in terms of providing guidelines for the design of baffle–avalanche wall systems for protection against rock avalanches.

     

基于ArcGIS的地图集索引快速制作

利用ArcGIS实现了地图集索引的快速制作,满足当前快速生产的需要,缩短了地图生产时间。     

利用废钢结硬质合金制备杂多酸

探讨了利用稀硫酸和浓硝酸分步处理废TLMW50钢结硬质合金,结合焙烧、浸取、结晶、水解、还原等方法,分离金属成分,制备12-磷钨酸、12-磷钼酸、绿矾、硫酸铬等化学试剂的生产工艺。     

新型纸制品粘合剂的研制和应用

玉米淀粉粘合剂的制备中关键是玉米淀粉改性的研究。改性剂在催化剂的催化下，C6原子上的伯羟基被氧化成醛基，然后氧化成波基，并且发生环断裂反应，从而能够抑制原淀粉分子缔合作用，提供性能稳定的不易老化的粘合剂糊液。改性淀粉的生产工艺一般有干法和湿法两种，干法的最大特点是没有三废，但对反应器的结构要求很高．反应副产物无法排除，产品杂质含量很大；湿法工艺反应非常均匀，设备通用性好、反应副产物可以排除，产品质量稳定，基本没有三废污染，我们采用了湿法工艺。首先将玉米淀粉制成悬浮液，在不断搅拌下加入催化剂、改性…     

平纹编织C/SiC材料复杂应力状态的力学行为试验研究

利用Arcan夹具,实现对2D平纹编织C/SiC复合材料拉剪、压剪加载试验,研究材料在复杂应力状态下的力学行为,分析材料的损伤演化和失效模式。试验结果表明,材料在拉剪复杂应力状态下不同角度的应力—应变曲线呈现非线性关系;在压剪复杂应力下,随着加载角度增大,应力—应变曲线非线性程度增大。断口分析表明纯剪切形成平齐断口,受拉应力影响材料在拉剪复杂应力状态下形成斜断口。试验分析表明,适当的压应力能提高抗剪切破坏能力。偏移型椭圆失效判据与试验值吻合较好,该失效判据能较好地描述材料在复杂应力状态下的破坏行为,能较好反映材料的强度特征。     

Security region based real and reactive power pricing of power system

This paper develops a novel model and an algorithm of security region based real and reactive power pricing of power systems. In the proposed model, the reactive power production cost is represented as the opportunity cost. The static voltage stability region in the cut set power space (CVSR) and the practical dynamic security region (PDSR) in the injection power space are used to represent the constraints of voltage stability and transient stability, so that the consideration of this kind of constraints in the optimization becomes very easy. In the proposed algorithm, a decoupled optimization and iteration method of active power production cost and reactive power production cost is suggested. According to the K-T optimality conditions, the prices of active power and reactive power, and the different components corresponding to the concerned security constraints are derived. The components of spot prices can reflect the influence of different node power injections on each kind of security constraints, so that through the node price all of the participants in power market can be stimulated to take an active part in maintaining the system security. An illustrative example on the New England 10-genetator 39-bus System is used to demonstrate the proposed method. Supported by the key research project of the National Natural Science Foundation of China (Grant No. 50595413)     

High harmonic exploring on different materials in dynamic atomic force microscopy

In atomic force microscopy(AFM), high-frequency components consisted in dynamic tip-sample interaction have been recently demonstrated as a promising technique for exploring more extensive material properties. Here we present an exploratory study of high harmonic atomic force microscopy by force-spectroscopy and high harmonic imaging. Since these components are very weak compared to the fundamental response, we firstly designed a high harmonic cantilever by tuning the second order flexural resonance frequency to an integer 6 times of its fundamental mode(i.e. ω_2=6ω_1). Moreover, it is verified that high harmonic can discern extra features than topographies on different samples with amplitude/frequency modulation(AM/FM) dynamic AFM mode. In AM mode, the first resonance amplitude and 6 th harmonic amplitude were discussed. The 6 th harmonic is more sensitive than the first order response. In FM mode, it is noted that the decaying rate of the 6 th harmonic frequency is approximately 6 multiples to the slope of the fundamental frequency shift when the tip approaches to the surface of sample. This non-destructive method was also adopted to investigate the local interlayer coupling and intercalation in the two-dimensional graphene films tentatively.     

魏秋良 虚怀谋大略

舍得—— 舍得舍得 先舍后得 不舍不得 大舍大德 记者：投资1600万元，征地60亩，如此大规模的扩大再生产，我想这绝不是魏总心血来潮。     

中国电梯风鹏正举——访中国电梯协会理事长任天笑

在我国改革开放滚滚洪流和经济全球化奔涌的狂潮中，创造传奇的中国电梯工业经过25年的历练，已经成为国际第大产销国。