《工程材料学》CAI网络教学平台的开发

介绍了计算机在《工程材料学》课程教学中的应用,阐述了网络教学平台的理论基础、设计原则和基本特点。并运用多媒体技术和网页制作软件,建立了《工程材料学》课程网络教学网站,探索了网络教学对教学模式的变革和创新。

丙烯酸-2,4,6-三硝基苯乙酯的合成及热分解

以TNT、甲醛为原料,在弱碱性条件下反应合成得到2,4,6-三硝基苯乙醇(PicCH2CH2OH);PicCH2CH2OH在浓硫酸催化下和丙烯酸在甲苯中回流反应24h,合成得到丙烯酸-2,4,6-三硝基苯乙酯,产率为62%。采用紫外可见光谱(UV-Vis)、核磁共振氢谱(1HNMR)、红外光谱(FTIR)、质谱(MS)以及元素分析等对产物结构进行了表征。利用热重分析(TG)对产物热稳定性进行了研究,采用Kissinger方法和Ozawa方法计算其热分解活化能Ea分别为99.78,102.96kJ·mol-1。

In situ Colonization of Marine Biofilms on UNS S32760 Duplex Stainless Steel Coupons in Areas with Different Water Qualities： Implications for Corrosion Potential Behavior

In the presence of biofilms, stainless steels （SS） exhibits an increase in corrosion potential, called ennoblement. In the present study, the corrosion potential （Eco,） behavior of the duplex SS UNS S32760 was recorded simultaneously with the in situ marine biofilm formation in two areas at Arraial do Cabo, Southeastern Brazil. The biofilm at Forno Harbor （an anthropogenically disturbed area） was characterized by higher relative abundances of Bacteria at day 2, followed by diatoms （especially Navicula sp.） on day 10 and dinoflagellates on day 18, whereas no clear trend was recorded at Cabo Frio Island （an undisturbed area）. The ennoblement of Ecor values was site-dependent. In a complementary laboratory assay, biofilms were removed and the Eco values registered in sterile conditions for the subsequent 10 days and corroborated in situ results. Understanding biofilms and SS interactions has important implications for materials science and engineering decisions as well as helping to fill in imnortant gaps in this knowledge.

On the Construction and Development of Strategies to Stimulate Learners＇ Motivation Concept and Evaluation Model

This paper starts from the theoretical basis of constructivism and development evaluation study that learns the principles of communication, the use of educational psychology and other disciplines of knowledge. It is to build a developmental evaluation and characteristics for the idea to the attention of the relevant confidence to meet and the evaluator＇ s expectations as of the five elements to stimulate learning motivation, build developmental evaluation principles to stimulate learning motivation of process model. Seven strategies are to stimulate and sustain the motivation of college students, while emphasizing mentor in the process of converting role as learner and developmental evaluation. Related strategies are used in the actual teaching of ＂Mechanical Engineering Materials＂ , ＂Graduation Design＂ , ＂Engineer Training＂ course, and it achieved satisfactory teaching effect, playing a role in promoting real learning and comprehensive evaluation of the development of college students.

Research of the Application of Nanometer Materials in Sports Engineering and the Biological Safety

In the modern material engineering, the use of nanometer materials has entered the highly and intensively utilized stage, so new nanometer materials have been continuously found to replace the traditional ordinary materials. The so-called nanometer materials have the size within l - 100nm in thickness, which originates from the 1980s. At that time, nanometer materials didn＇t have a proper development due to the economic level. t towever, with the support of science and technology, this technology has undergone tremendous changes in the related fields. There have been increasing expansion in the kinds and the width in use of the nanometer materials, so have the research of nanometer materials. In this paper, we will briefly analyze the application ofnanometer materials in the sports engineering.

Measurement Analysis in Electrochemical Discharge Machining （ECDM） Process： A Literature Review

Electrochemical discharge machining is considered to be a hybrid machining process that combines with EDM and ECM （electro chemical machining）, called ECDM. The material removal is based on two phenomena： electrochemical dissolution of the material and thermal erosion of electrical discharges that occur between the cathode ＆ anode electrodes. This process is better used for machining of non conducting materials efficiently. In this research paper shows that a brief literature review study of various measuring instruments used for analysis of various parameters of the electrochemical discharge machining process on various types of materials, tool material, input ＆ output parameters such as surface roughness, surface texture, material removal, tool wear etc..

Evolution of Building Envelopes through Creating Living Characteristics

Building envelopes include facades and roof, which have the most interaction and exchange with outside and natural environment. In the future, meeting buildings various complicated needs with new technological advances necessitates a change and evolution in building envelopes. Controlling the energy consumption of the buildings is mostly through controlling the energy performance of the building envelopes. New technologies lead to the intelligent facades and envelopes. The envelope can be designed to be a part of the whole building＇s metabolism （energy production, storage and consumption） and morphology. The envelope would be a controlled part of the building which is managed through the central control system of the building, which connects it to other parts. It caused building envelope design to be changed fundamentally, so that there is a need to interact with engineering disciplines including computer engineering, mechanical engineering, material engineering and so on. All of these caused building envelope to get closer to biological and living systems. The physical restrictions which affect buildings system and living systems are the same. So they cause the same forces to shape the structure and form of the systems and the same rules to interact with the environment. The restrictions of material and energy resources caused living systems to be energy efficient and consuming less material. But the most important difference between living systems and building systems is in maximum use of different resources. As living systems use information maximally, the building system technology is based on using maximum energy. Now, there are many reasons and restrictions that building envelopes cannot act like living systems. But technological developments and contributing more disciplines in design and construction of building envelopes caused the future way of these envelopes get close to living systems for their energy efficiency. Some of living systems characteristics which the future building envelopes would have partially or benefit for the design process or construction are self-organization, evolution principles, hierarchical levels, processing energy, reaction to environmental stimuli and self-adjustment. Self-organization is achieved in some design software and in building material production for creating formal patterns. Evolution principles provide infrastructure for soft wares for optimization purposes and form creation. Hierarchical levels refer to giving hierarchical structure to the building envelopes through layering and designing different scales. Processing energy （metabolism） would be achieved through photovoltaic and solar collectors to produce energy and in passive systems for energy storage and distribution. Controlling solar radiation absorption and transmittance would help energy transfer from outside to building and vice versa. Reaction to environmental stimuli which is one of the most important characteristics of future building envelopes would use different types of active and passive sensors to create envelope mechanical reactions through material properties or collect data for processing in the control center to determine the right reaction. The reaction would be through different strategies such as changing properties and moving. Reaction could be passive or active. Self-adjustment can be achieved by control systems and processing units. All of these mean intelligent envelopes are essential parts of future buildings. Though it is now started with new design soft wares based on biological principles to optimize different parameters affecting the envelope function or to create the most efficient form.

Study on Characteristics of Acellular Bovine Pericardium Crosslinked with Genipin

The study used a naturally occurring crosslinking reagent-genipin to chemically modify acellular bovine pericardium, prepare cardiac valve tissue engineering scaffold material,and evaluated genipin crosslinked acellular matrix of bovine pericardium by investigating the physical and chemical properties of the tissues, such as the surface properties, crosslinking characteristics, mechanical properties, resistance to enzymatic capacity in vitro, and hemolysis tests. The results showed that acellular bovine pericardium matrix erosslinked with genipin was strong hydrophilicity, high crosslinking index, and stable structure, which can maintain good mechanical properties. As a kind of scaffold material for valve tissue engineering, it has wide application prospect.

Study on the computation method of temperature field of RCC dam

According to the construction characteristic of RCC dam cast by layers, three-dimensional finite element relocating mesh method is developed to simulate construction process and compute temperature field. The computation model of relocating mesh method is expatiated in detail; based on the thermodynamic properties of RCC materials, the feasibility and error of relocating mesh method are analyzed and demonstrated; The computation results in this article are verified by means of the temperature observation data of certain RCC gravity dam. The results show that the temperature field computed by three-dimensional finite element relocating mesh method can not only ensure the computation precision, but also improve the calculation efficiency greatly. This provides an effective method for simulating construction process and computing temperature field of RCC dam.

Analysis of Through-the-Thickness Stress Distribution in Thick Laminate Multi-Bolt Joints Using Global-Local Method

The stress distribution surrounding the fastener hole in thick laminate mechanical joints is complex. It is time-consuming to analyze the distribution using finite element method. To accurately and efficiently obtain the stress state around the fastener hole in multi-bolt thick laminate joints, a global-local approach is introduced. In the method, the most seriously damaged zone is 3D modeled by taking the displacement field got from the 2D global model as boundary conditions. Through comparison and analysis there are the following findings: the global-local finite element method is a reliable and efficient way to solve the stress distribution problem; the stress distribution around the fastener hole is quite uneven in through-the-thickness direction, and the stresses of the elements close to the shearing plane are much higher than the stresses of the elements far away from the shearing plane; the out-of-plane stresses introduced by the single-lap joint cannot be ignored due to the delamination failure; the stress state is a useful criterion for further more complex studies involving failure analysis.

Influence of freezing rate on cryo-damage of cementitious material

We report an experimental investigation on the impact of the freezing rate on the cryo-deformation and cryo-damage of cementitious materials.Saturated,dried and air-entrained mortar specimens are subjected to laboratory freeze-thaw cycles under three freezing rates without moisture exchange with the environment.In addition to basic mechanical properties and pore distribution,the measurement is also effectuated for freezing expansion,residual deformation of the specimens in each cycle.From the results it is observed that a high freezing rate does augment the freezing expansion of material while the cryo-damage is more important for a low freezing rate.Accordingly,both the freezing rate and freezing duration should be taken into account for the cyro-damage extent of cementitious materials.

Interface energetics and engineering of organic heterostructures in organic photovoltaic cells

The reliable information about interface energetics of organic materials, especially the energy level alignment at organic heterostructures is of pronounced importance for unraveling the photon harvesting and charge separation process in organic photovoltaic(OPV) cells. This article provides an overview of interface energetics at typical planar and mixed donor-acceptor heterostructures, perovskite/organic hybrid interfaces, and their contact interfaces with charge collection layers. The substrate effect on energy level offsets at organic heterostructures and the processes that control and limit the OPV operation are presented. Recent efforts on interface engineering with electrical doping are also discussed.

Scientific Evaluation and Regeneration of Eco-building Experience in Traditional Dwellings

In 1996, Department of Engineering and MaterialSciences,National Natural Science Foundation (NSFC), accepted the suggestion made by some experienced members of CAS and published the key support project Green Architecture System and Dwelling Pattern in application guide for NSFC project. The project research group, led by Prof.

Feasibility analysis of high excess pressure cockpit using material substitution based on strain energy

The design concept of high excess pressure cockpit has been proposed as a solution to solve the ergonomics problems caused by cockpit environment.To address the contradiction among mass,economy,maneuverability and environment ergonomics,considering the composite advantages of high strength and lightweight,the feasibility analysis concept of high excess pressure cockpit based on material substitution is proposed in the paper.Based on the strain energy analysis on finite element model,the iteration design method of equal stiffness and lightening effect analysis on material substitution are presented,The weight reduction effect after material substitution can be evaluated intuitively by using equal stiffness curve.The calculation result of cockpit indicates that the lightening effect can reach 35.09%.Because of the complexity of cockpit design,bi-level optimization method is proposed and performed by means of the First-Order Radio algorithm.The research shows that the method can achieve good result.The feasibility of high excess pressure cockpit is studied from the aspect of the relationship between excess pressure and mass,and the research demonstrates that,due to the utilization of T300/4211 in place of 6061 alloy,the excess pressure of cockpit increases from 35 to 45 kPa,a 28.57%increase,while the cockpit mass is decreased by 12.56%.Thus,the contradiction among mass,economy and environment ergonomics can be coordinated,which can provide a reference for the design of high excess pressure cockpit.

Defects production and mechanical properties of typical metal engineering materials under neutron irradiation

Maintaining the safety and reliability of nuclear engineering materials under a neutron irradiation environment is significant. Atomic-scale simulations are conducted to investigate the mechanism of irradiation-induced vacancy formation in CLAM, F82 H and α-Fe with different neutron energies and objective laws of the effect of vacancy concentration on mechanical properties of α-Fe. Damage of these typical metal engineering materials caused by neutrons is mainly displacement damage, while the displacement damage rate and the non-ionizing effect of neutrons decrease with the increase of neutron energy. The elastic modulus, yield strength, and ultimate strength of α-Fe are in the order of magnitude of GPa. However, the elastic modulus is not constant but decreases with the increase of strain at the elastic deformation stage. The ultimate strength reaches its maximum value when vacancy concentration in α-Fe is 0.2%. On this basis, decreasing or increasing the number of vacancies reduces the ultimate strength.