《结构力学》课程体系设置之探讨

在新形势下,为培养适应社会需求的人才和造就优秀的土木工程师,结构力学作为一门重要的专业基础课,其课程体系的设置不仅需要将原有的内容按照一定的主线进行删减和整合,而且需要注入新的内容,比如大量工程实例、结构分析程序、定性结构力学等。     

Silver catalysts supported over activated carbons for the selective oxidation of CO in excess hydrogen: effects of different treatments on the supports

Commercial activated carbon (AC) was used as a support either in its original form or after various modifications, giving diverse textural and surface chemical characteristics. The changes of these properties were monitored by N₂ adsorption–desorption isotherms, temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). Ag catalysts were prepared over the AC supports by a conventional wet impregnation method. The catalytic performances of supported Ag/AC catalysts in the selective oxidation of CO in excess H₂ were tested. The results indicate the textural and surface chemical characteristics are responsible for the different catalytic performances.     

桁架结构计算方法探讨

笔者在深入研究了桁架结构的经典计算方法之后,提出了一种新的计算方法——“轴力系数趋势平衡法”.这一方法不用力的投影平衡方程而使用了轴力系数的“趋势平衡”方程进行计算,从而在许多情况下使繁锁的桁架计算变得异常简捷。文中推导了方程,叙述了基本原理与方法,并通过例题证明了该方法的正确性与优越性。     

Advancing Africa’s Great Lakes research and academic potential: Answering the call for harmonized,long-term,collaborative networks and partnerships

The African Great Lakes (AGL) have rich fisheries and are renowned “biodiversity hotspots”. Consequently the AGL and the ecosystem services they provide, underpin the welfare and livelihoods of over 50 million people across 10 countries. Despite the recognized importance of the AGL, these vital ecosystems and their livelihood support systems are threatened by numerous anthropogenic stressors at local, regional, and global scales. Past and continued efforts to address critical challenges on these lakes are often short-term, parochial, disparate, and uncoordinated resulting in a lack of comprehensive and comparable scientific data and inadequate resources to influence evidence-based policy. Over the past two decades, several international workshops, conferences and scientific publications have identified the need for collaboration, knowledge sharing, and harmonization of research and management as key elements to enhance conservation efforts in the AGL. In this commentary, we introduce the African Center for Aquatic Research and Education (ACARE), which aims to strengthen research and provide the scientific evidence needed to make informed decisions related to sustainable fisheries and aquatic resource management in the AGL. To do this, ACARE will administer a highly collaborative network of experts with three long-term goals: (1) strengthen global and regional research partnerships; (2) establish transboundary and inter-jurisdictional lake advisory groups; and (3) build capacity of freshwater scientists through experiential education and public engagement.     

面向多区域防洪的长江上游水库群协同调度模型

长江上游水库群是长江流域防洪工程体系的重要组成部分,承担着水库所在河流、川渝河段以及长江中下游的防洪任务。长江流域面积广大,水系众多,洪水地区组成与遭遇十分复杂,防洪需求众多,防洪对象分散,且要兼顾发电、航运、供水、生态、库区安全等多种因素,水库群防洪调度面临大规模、多区域、多层次等协同调度技术难题。以长江上游25座控制性水库为研究对象,基于防洪格局和防洪任务将水库群防洪调度划分为核心、骨干和群组水库,阐明了水库群多区域协调防洪的调度节点和角色定位,提出了兼顾"时-空-量-序-效"多维属性的模型功能结构,构建了长江上游水库群多区域协同防洪调度模型,并在长江流域防洪调度形成示范应用,以挖掘长江上游水库群防洪调度潜力,进而提升长江流域防洪调度管理水平。     

Characteristics of coal sludge slurry prepared by a wet-grinding process

Coal sludge slurry(CSS) is an alternative fuel and a potential competitive method for sludge reduction.Based on the researches of coal water slurry, we studied CSSs by using a wet-grinding process with different types of regional municipal sludge(sludge) in an orthogonal experiment. The sludge type,sludge mixing proportion, dosage of dispersant, and grinding time were tested in this study. The results show that water content and its occurrence characteristics in the sludge have primary hindering influences on slurry ability. The range of fixed-viscosity concentrations with raw wet sludge is from 50.78%to 44.40%(by weight), while the range is from 53.35% to 51.51%(by weight) with dry sludge. All of the CSSs exhibit shear-thinning behaviors with different variation trends, especially the CSSs with more than 15%(by weight) raw wet sludge in it. Adding the same proportion of raw wet sludge increases the thixotropic properties of CSSs and the highest area of thixotropy loop is 3065 Pa/s, while the highest value of dry sludge is 1798 Pa/s. Hydrophilic group plays an important role in adsorbing water and building three-dimension networks with other particles, which is the main reason for CSS properties.Therefore, the mechanism can be used to find the way for making high quality CSS.     

Structural optimization of 2-D array probe for alternating current field measurement

A double U-shaped orthogonal inducer for the alternating current field measurement (ACFM) is presented, which could extend the limitation of the direction of tested cracks and decrease the loss of magnetic flux compared to the single rectangular inducer. The structure of the testing probe was optimized to meet the expectations of the pointwise magnetic field measurement and to decrease every group of coils’ space by orthogonally winding method, and the two-dimensional (2-D) ACFM probe array was designed. The detection precision and lift-off effect of the 2-D ACFM probe array were experimentally studied. The results show that the relative error of this probe is less than 10%, and it could suppress the lift-off disturbance effectively, which makes this 2-D ACFM probe array to be insensitive to lift-off and unable to meet the engineering expectations.     

压铸镁合金在汽车方向盘上的应用研究

通过对SC6380客车方向盘生产所用镁合金系的选择、方向盘服役模型建立、弹性有限元分析、结构再设计、压铸工艺虚拟设计及数值模拟等步骤，初步探索了镁合金方向盘的开发过程，为倡导镁合金等新材料在方向盘上的合理应用提供了技术支撑平台，通过以上步骤能有效的缩短产品开发周期。