关键词： mechanoradical   kinetics   kaolinite  

摘要： Kaolinite is a versatile material with many applications in various fields such as in cosmetics or wastewater treatment. Here, we report the first evaluation of mechanoradicals formation on activated kaolinite powders, and its kinetics, via wet-grinding in ethanol using a free-radical scavenger (2,2-diphenyl-1-picrylhydrazyl;DPPH). Increasing the duration of ball milling of two reference kaolinite samples resulted in increased DPPH consumption due to an increase in the surface area of the processed powders. The correlation between the increasing rates of the surface areas and DPPH consumption yielded information on the density of radical species that may react with ethanol to form H radicals on the newly created surfaces of the kaolinite powders. The radical density was much lower than that reported previously for quartz, possibly due to the anisotropic nature of the kaolinite crystal structure. The actual surfaces that take part in the radical formation reaction were mainly newly created edge surfaces rather than basal surfaces. The kaolinite sample with fewer defects was more resistant to delamination, and thus its edge-to-basal surface-area ratio was also higher, which may have resulted in higher reactivity during mechanical processing. This knowledge is key for industrial applications of processed kaolinite powders.

关键词： crosslinking   differential scanning calorimetry   resins   theory and modeling   thermosets  

摘要： This work reports on nonisothermal degradation kinetics of polyurethane (PU)-based powder coatings containing 1, 3, and 5%wt% vinyltrimethoxysilane functionalized Al2O3 (V-Al2O3) nanoparticles. Thermogravimetric analysis of PU/V-Al2O3 powder coatings with different V-Al2O3 contents has been performed at different heating rates. Variation of activation energy (E-a) of PU/V-Al2O3 powder coatings was modeled as a function of partial mass loss by using Kissinger-Akahira-Sunose, Ozawa-Wall-Flynn and modified Coats-Redfern isoconversional approaches. The results revealed hindered decomposition process of PU/V-Al2O3 nanocomposite powder coatings, featured by an increase in activation energy of degradation from similar to 158 for blank PU to 225, 183, and 229 kJ/mol for nanocomposites filled with 1, 3, and 5 wt% of V-Al2O3, respectively. Likewise, pre-exponential factor values increased for samples containing V-Al2O3 nanoparticles compared to that of blank sample. Sestak-Berggren kinetic model appropriately captured thermal degradation behavior of PU/V-Al2O3 nanocomposites than that of nth order decomposition kinetic reaction models.

关键词： 纯电动汽车   锂离子动力电池   标准   安全要求  

摘要： 随着锂离子动力电池在电动汽车上的广泛应用,其安全性得到越来越多的关注。分析了国内外锂离子动力电池在机械安全方面的测试标准,对机械冲击试验、跌落试验、翻转试验、针刺试验、振动试验、海水浸泡试验方法中的试验条件和参数进行了比较分析。指出了相关标准存在的不足,并指出了不同标准之间因试验条件不同而不具有可比性。

关键词： 动力中心   锅炉   起重机械   配置  

摘要： 石化工程动力中心具有作业面广、安装工作量大、场地空间小、工期紧、起重机械吊装作业繁忙等特点。本文介绍了4000万吨/年炼化一体化项目(二期)动力中心公用工程特点及吊装难点、施工组织与起重机选型、主要大件吊装、起重机械管理体会等方面作了详尽的阐述。

关键词： Supramolecular hydrogels   Mechanical strengthening   Crosslinking kinetics   DNA Hydrogels   Dynamic features  

摘要： Supramolecular hydrogels display unique dynamic features such as self-healing and injectability which are endowed by their non-covalent crosslinking. These extraordinary dynamic properties enable them to be broadly applied in various fields, but also decrease their mechanical strength. This inherent contradiction between mechanical strength and dynamic features has posed great challenge to their practical applications. This article provides an overview of emerging techniques for mechanical strengthening of supramolecular hydrogels with preserved dynamic features. Inspired by the "strong means slow" principle of transient supramolecular networks, particular focus is placed on how the exchange kinetics of the supramolecular crosslinkers can be engineered to tune their mechanical strength. Some other effective strengthening strategies are also reviewed, which are usually combined to realize the coexistence of mechanical strength and dynamics. Meanwhile, we point out the future development of supramolecular hydrogels with unique mechanical properties and their potential challenges.

关键词： Molecular dynamics   Coarse-graining   Carbon and silicon nanostructures   Tersoff potential   Stillinger-Weber potential   Mechanical and thermal properties  

摘要： The main concern in Molecular Dynamics (MD) simulations is the computational cost, and coarse-graining methods accelerate simulations by reducing the degrees of freedom in the system. Yet, the utilization of these methods should be carefully followed. In this paper, we presented an energy-based coarse-graining method for Tersoff and Stillinger-Weber potential functions. The presented coarse-graining method is based on the domain mapping and modification of potential function. The focus of this paper is on Carbon and Silicon materials;however, this method can be applied to model other materials for which Tersoff and Stillinger-Weber potentials are defined. This method has been validated by demonstrating the consistency of mechanical properties between all-atom and CG models in different case studies. According to the conducted simulations, the precision of the proposed CG technique in the modeling of the bulk behavior is near 100% while it yields completely reasonable results for other simulation setups.

关键词： 机械手   三自由度   雅克比矩阵   ADAMS  

摘要： 基于ADAMS的仿真技术,对工业机械手进行运动学和动力学仿真上的分析。对于三自由度工业拾取机械手,通过D-H方法[1]建立每个连杆的参考坐标系,首先研究了机械手的主要理论及数学基础,得到了机械手运动学的方程,给出抓取机械手的每个连杆与末端执行器之间的姿势关系,并推导出机械手的运动学方程,利用微分变化法获得雅可比矩阵。通过连杆间力和力矩的递推求得力雅可比矩阵以验证机械手建立的正确性。然后在ADAMS中对机械手运动进行仿真使用后处理模块,在各个关节处分别添加驱动函数,并验证了该机制的可行性。

关键词： 舰船正撞   动力机械   振动冲击   荷载作用  

摘要： 传统方法分析冲击荷载作用时,在连续碰撞时间内,荷载拟合曲线波动较大,导致计算荷载值存在误差。为此,提出舰船正撞后动力机械的振动冲击荷载作用分析研究。将冲击荷载值计算,转换为冲击波的传播问题,拟合冲击荷载曲线,排除机械装置自重影响因素,获取机械速度谱、位移谱和加速度谱的关系式,可得在冲击荷载作用模式下,机械位移谱产生改变,结构响应与动力结果产生吻合。与传统方法进行对比实验,结果表明,此次分析方法减小了荷载值计算误差,对动力机械位移谱判断更为精确,从而降低动力机械正撞后的受损程度。

关键词： 在读研究生   材料成型及控制工程   全日制本科   能源与动力工程   机械制造及其自动化   机械电子工程   工程训练中心   卓越工程师教育培养计划  

摘要： 2014年1月原机械与材料学院更名为机械与动力学院,学院现设有机械设计制造及其自动化、机械电子工程、材料成型及控制工程、M工程、能源与动力工程、核工程与核技术六个本科专业,其中机械设计制造及其自动化为国家特色专业、第二批卓越工程师教育培养计划专业和省本科品牌专业,材料成型及控制工程为第三批卓越工程师教育培养计划专业。拥有机械工程一级硕士点、机械工程专业学位点、机械工程领域工程硕士点、工业工程专业学位点,机械制造及其自动化为湖北省重点学科。目前,在校全日制本科学生近2000人,在读研究生160余人,毕业生的一次就业率一直保持在90%以上。学院拥有水电机械设备设计与维护湖北省重点实验室,工程训练中心等,实验室建筑面积1・2万平米,设备仪器总值2000余万元。

关键词： 导师队伍建设   博士生导师   动态遴选   导师培训  

摘要： 博士生导师是博士生培养的第一责任人,是博士生培养质量提高的关键角色。上海交通大学聚焦导师队伍,将导师队伍作为师资队伍建设的重点,创新性地采取博导动态遴选制度,提高导师队伍的竞争力和学术活跃度;推行常态化岗位培训,促进博士生导师成长、成熟。多措并举,形成具有工科特色的博士生导师队伍建设体系,助力于落实导师的岗位职责和导师队伍的健康发展。