关键词： failure properties   molecular dynamics   solid polymer electrolyte   viscoelastic properties  

摘要： This reactive molecular dynamics study explores the salt concentration dependence of the viscoelastic and mechanical failure properties of a poly(propylene glycol)/LiPF6-based solid polymer electrolyte (SPE) at a graphitic carbon electrode interface. To account for the finite-size effect of interface-confined SPE films, the properties of two distinct film thicknesses are compared with the respective bulk properties. Additionally, the effect of uniaxial compression in the interface-normal direction on free energy profiles of Li-ion SPE-desolvation is studied. (c) 2018 The Authors. Journal of Polymer Science Part B: Polymer Physics Published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 718-730

关键词： 农业机械化   合作社   现代农业   北镇市  

摘要： 北镇市紧紧围绕粮食生产功能区和现代化农业机械化技术推广,大力扶持发展设施完备、功能齐全、管理规范、效益显著、充满活力的农机专业合作社,提高了当地的农机专业化和社会化服务水平,走出了一条规模化经营、机械化生产、社会化服务、产业化发展的农机合作社发展新路。

关键词： 金属材料   机械设备   翻转机构   动力学   建模分析  

摘要： 金属材料机械设备的运转已经是大势所趋,但存在金属材料机械设备还存在自动化运转不够合理的问题,为此提出了金属材料机械设备翻转机构动力学特性建模分析。以金属材料机械设备翻转机构的等效力矩模型以及金属材料机械设备翻转机构的等效转动惯量模型为前提,进行金属材料机械设备翻转机构动力学方程设计,并通过仿真实验对其结果进行分析,以期实现更加有效地金属材料机械设备的运行。

关键词： 内燃机   汽轮机   燃气轮机   水轮机   风力机   电动机   流体传动装置  

摘要： 本文介绍了动力机械的相关定义及选用因素,同时重点阐述了内燃机、汽轮机、燃气轮机、水轮机、风力机、电动机及流体传动装置之间的相互区别并进行对比,同时明确了其具体应用领域。为相关领域工作人员提供了必要的理论依据。

关键词： 翻转课堂   机械动力学   教学改革  

摘要： 机械动力学是很多工科专业本科和研究生的重要课程,并已成为工程技术人员必须具备的理论知识。本文针对以往教学中,研究生主观能动性发挥不足,很多研究生不会提问题和提不出问题的现象进行了教学改革,采用翻转课堂的方式,结合案例教学法,取得了良好的效果。

关键词： annealing treatment   Avrami exponent   blue brittleness temperature   prestrain temperature   rolling process   static recrystallization   tensile properties  

摘要： In this research, the samples of a low carbon steel sheet were rolled up to a thickness prestrain of 67% at three different temperatures consisted of room, blue brittleness, and subzero temperature. Microhardness, SEM, and tensile tests were carried out to evaluate the static recrystallization kinetics defined by the Avrami equation, microstructural evolution, and mechanical properties. It was found that the Avrami exponent is altered with change in prestrain temperature and it achieves the value of 1 to 1. 5. Moreover, it was indicated that prestraining at subzero temperature followed by annealing at 600 A degrees C leads to considerable enhancement in tensile properties and kinetics of static recrystallization compared to room and blue brittleness temperatures. The prestraining at blue brittleness temperature followed by annealing treatment caused, however, a higher strength and faster kinetics compared with that at room temperature. It was concluded that although from the steel ductility point of view, the blue brittleness temperature is called an unsuitable temperature, but it can be used as prestraining temperature to develop noticeable combination of strength and ductility in low carbon steel.

关键词： cable   crystallization kinetics   electron beam   fluoride precipitation   mechanical performance   XETFE  

摘要： The cross-linking effects of cross-linked ethylene-tetrafluoroethylene copolymer (XETFE)-insulated cables at different electron beam radiation doses were analyzed in this paper. Evaluation of the mechanical performance of the cables revealed that the highest tensile and breaking elongation was achieved at a radiation dose of 8x10(4)Gy and that XETFE had a good resistance to extreme electron beam irradiation. This is attributed to the cross-linking effects induced by electron beam irradiation, and this takes full advantage of the strength of molecular chain crosslink to each other. The crystallization kinetics of XETFE at different electron beam radiation doses were studied in detail in terms of the non-isothermal and isothermal crystallization processes. The results indicated that the crystallinity of the XETFE domain increased with an increase in the radiation dose as a result of heterogeneous nucleation. Moreover, the highest E-a was obtained, indicating that XETFE absorbed some energy at a radiation dose of 8x10(4)Gy. These kinetic parameters had help in carrying out a comprehensive evaluation of the performance of XETFE-insulated cables for aerospace applications. Moreover, the fluoride precipitation observed in this study indicated that upon electron beam irradiation, XETFE could internally produce hydrogen fluoride, which is corrosive to metals. Thus, optimizing the radiation dose was necessary to achieve the desired performance. We could believe that the improvement for properties of electron beam XETFE insulation cables would expand their range of applications in the aerospace field.

关键词： High Density Polyethylene   Composite   Chemical Treatment   Mechanical Behavior   Water Absorption Kinetics  

摘要： The objective of this work was to investigate the effect of surface improvement on human hair fiber (HF) based high-density polyethylene (HDPE) reinforced polymer composites. A universal testing machine was used for the characterization of the mechanical behaviors of different types of HF base reinforced HDPE composites, and studies were conducted for the optimization of male/female fiber percentage (15% HF) in polymer composites. The alkali treatment (AT) and acrylic acid treatment (AAT) of HF reinforced HDPE composites showed a remarkable improvement in tensile strength (upto 15.487MPa and 15.638MPa, respectively), which was significantly changed in comparison to the tensile strength of untreated composites. FTIR and SEM test were used to characterize the fiber surface and HF/HDPE reinforced composites. Water absorption kinetics was investigated for the study of diffusion mechanism and kinetics of composites materials, which would be useful to boost the applications of the composite in different areas.

关键词： Self-power   Optical wireless transmission   Mechanical sensing   Triboelectric nanogenerators  

摘要： The ubiquitous sensors have accelerated the realization of Internet of Things (IoT) but also raised challenges to the current overcrowding radio frequency (RF) based communications. The optical wireless communication (OWC) that utilizes the wide optic bandwidth can well solve the spectrum crisis and is an appealing complementary solution to the IoT applications. However, the additional direct current (DC) power supply and complicated modulating and power management circuits may limit the large-scale deployment of OWC systems. In this paper, by integrating with triboelectric nanogenerators (TENGs), the light-emitting diode (LED) could be directly transformed into a wireless transmitter that conveys the information associated with mechanical stimuli without additional power supply. With the customized TENG devices and the help of advanced image processing and machine learning techniques, three demonstrations with functions of optical remote control, pressure sensing, and security authentication, were demonstrated. The concept and results in this paper may greatly broaden the application of IoT through the integration of OWC and TENG.

关键词： Annealing   Microstructure evolution   Steel/aluminum interface   Intermetallic compound layer   Mechanical property  

摘要： In this paper, an annealing treatment was performed to eliminate the work hardening effect of cold roll bond clad sheets, and the effect of annealing temperature and time on the microstructure evolution at steel/aluminum interface and mechanical properties of aluminum-steel clad sheet were investigated. Results showed that the longer the time and the higher the temperature are, the thicker the inter diffusion zone become. Fe2Al5 phase preferentially formed at the inter-diffusion layer at 600 degrees C. As the annealing temperature increased, another FeAl3 phase gradually formed. The thickness of intermetallic compound layers over 10 mu m would seriously deteriorated the mechanical properties of aluminum-steel clad sheet. Furthermore, the relationship of the thickness of inter-diffusion layer with the annealing time and temperature was established, which played a vital role in predicting the working time of aluminum steel clad sheet. (C) 2018 Elsevier Ltd. All rights reserved.