Exergetic analysis of fuel cell micropowerplants fed by methanol

In the present study, a hydrogen polymer electrolyte fuel cell (PEFC) micropowerplant in combination with a steam reformer fed by methanol and a direct methanol fuel cell (DMFC) micropowerplant are analyzed numerically regarding their exergetic efficiency. The effects of concentration and activation overpotentials, and ohmic resistance on the efficiency are considered in quasi-two-dimensional fuel cell models. The influence of significant operational parameters on the exergetic efficiency is examined numerically. Experimental results are conducted for the steam reformer. This work shows the importance of an exergy analysis of the fuel cell as part of an entire thermodynamic system generating electric power and compares PEFC and DMFC micropowerplants exergetically.     

Effect of cooling rate on the electrochemical properties of solid-state synthesized spinel LiMn2O4

LiMn₂O₄ samples were prepared by solid-state reaction with different cooling rates (0.5, 1, 3, 5 °C min^− 1, and quenching) from Li₂CO₃ and electrolytic MnO₂. X-ray diffraction patterns of the prepared samples are identified as the spinel structure with a space group of Fd3¯m. The lattice parameters increase gradually as the cooling rates rise. The quickly cooled samples show better capacity properties at high current densities and a capacity fade when cycling at lower current density. Varieties of electrochemical methods were introduced to investigate the electrochemical properties of spinel LiMn₂O₄.     

Low operational temperature Li–CFx batteries using cathodes containing sub-fluorinated graphitic materials

Commercial lithium/polycarbon monofluoride batteries [Li–(CF)_n] are typically current-limited and are therefore not implemented in high-rate or low-temperature applications. Recent results suggest, however, that CF-based cathodes that use sub-fluorinated CF_x (SFCF_x) active materials in a thin electrode form factor are able to support very high currents (up to 5 C) while still providing a significant fraction of their specific capacity. In this work, the low temperature efficacy of these materials is examined in a −40 °C environment. CF_0.54 and CF_0.65 powders were characterized using X-ray diffraction, scanning electron microscopy, and X-ray energy dispersive spectroscopy. These materials were then implemented in a spray-deposited electrode using a 1-mil (∼25 μm) aluminum foil current collector and PVDF as a binder. Electrochemical tests showed that these materials were able to deliver specific capacity values up to five times greater than commercial CF_1.08 powder inserted into identically fabricated test cells tested at −40 °C. Testing also indicated that a room-temperature pre-discharge step was necessary to condition the electrode materials before exposure to the low-temperature test environment.     

基于神经网络的出入境货物宏观质量指数研究

以检验检疫情况统计数据为基础,运用感知器神经网络理论,对货物的宏观质量指标及其评价方法进行了研究。该方法为出入境货物的检验检疫宏观监控提供了决策依据。     

货物配装模型与算法研究

货物合理配装在物流配送中发挥着重要作用,影响货物配装的因素有很多,诸多因素影响的是货物的配装优先级。以配装优先级为基础,提出了基于优先级理论的货物配装模型和求解算法。算例分析验证了所提方法的有效性。     

空穴载流子在多晶p-ZnO薄膜中的输运特性研究

利用变温霍尔测量技术,研究了空穴载流子在Li和N双受主掺杂的p型ZnO多晶薄膜中的输运特性。实验结果和理论模型的比较研究表明：当温度在85～140K时,空穴载流子主要受晶界散射;当温度在140-300K时,空穴载流子主要受晶格振动散射、位错散射和电离杂质散射的共同作用。     

基于LabVIEW的汽车发电机外特性虚拟检测平台技术

针对汽车发电机输出外特性的测量问题,研究了采用虚拟仪器方法的汽车发电机自动检测平台技术的可行性方案,提出了基于LabVIEW的汽车发电机外特性自动检测系统的模型、结构、设计和实现技术,并对其平台技术设计的原理、思想及其路线进行了论述。实验表明：自动检测平台技术提高了汽车发电机外特性检测的质量。     

数字化产品设计中多形态知识集成

针对产品数字化设计过程中知识重用的特点,对设计知识进行了比较全面的分类,提出了产品设计过程中多形态知识的概念。研究了多形态知识集成的方法,给出了基于领域本体的多形态知识融合方法,并以螺纹滚丝机设计中多形态知识为例,对该方法进行了解释,得出了相关结论。     

金属锂负极改性研究现状

综述了金属锂二次电池中金属锂负极改性的研究进展。主要介绍了电解液添加剂、金属锂保护膜、新形态锂电极等主要改性方法,并对以后锂电极的发展趋势进行了展望。     

发电设备检修策略分析

阐述了发电设备检修体制的演变和发展,并对我国现有的主要检修策略进行了对比分析,提出了融合故障检修、定期检修和状态检修为一体的优化的综合检修策略,从而为提高设备可靠性、降低设备检修成本、全面提高发电设备检修管理水平提供有效的手段。