Single-switch boost-buck DC-DC converter for industrial fuel cell and photovoltaics applications

The realization of dc-dc converters performs a vital function in exploiting renewable energy sources such as solar photovoltaic (PV) and fuel cell applications. This paper demonstrates a single-switch unidirectional buck-boost dc-dc converter for continuous power flow control, excluding the hybrid switched-capacitor. The proposed converter utilizes a limited number of passive components, only four diodes and three inductors required, in addition to six capacitors. The converter can operate at a wide input voltage range with continues input current. The converter has experimented under real-time conditions with 660 W PV system. The obtained efficiency ranges from 93% to 98%. Furthermore, the converter has interfaced with 550 W fuel cell operated under different fuel pressure. The realized efficiency ranges from 91% to 97%. The maximum measured inductance current ripple is limited to under 0.70 A in both scenarios, whereas 0.16 V is the maximum output voltage ripple.     

浅谈电子电工技术在电力系统中的应用

本文针对电子电工技术在电力系统中的作用进行了分析,同时为该技术的推广提出了相应的建议。     

Steering feel improvement by mathematical modeling of the Electric Power Steering system

Currently, the Electric Power Steering (EPS) system is an essential component of the vehicle because it provides assistive steering torque to the driver. To ensure a faster steering response, the position of the EPS in some vehicles is moved closer to the tire rather than the steering wheel. The steering torque, which is provided by the EPS in the steering system, mainly affects the driver’s feel while steering. Therefore, the driver often feels uncomfortable owing to such positioning of the EPS in the steering system. In particular, the nonlinearity of the Universal Joint (UJ), which is one of parts of the steering system, can be felt at the steering wheel side.In this paper, we proposed an algorithm based on the mathematical model of the steering torque in the steering system to improve the steering feel. The mathematical model is structured using parameters that can be obtained from the information of the steering system. Moreover, the formulation of the steering torque consists of the two parts, namely the deformation part, which describes the propagation inside the steering system, and the friction part that describes the inherent friction in the UJ.Simulation and experiments were conducted to verify the proposed mathematical model with similar conditions to the real tire load during the steering motion. Furthermore, to improve the driver’s feel during steering, a torque compensation algorithm is proposed and verified through experiments.     

基于特征建模的TDD系统大气波导干扰控制体系研究

大气波导干扰是特定气象条件下发生的时分双工（time-division duplex，TDD）系统内干扰，是TDD移动通信系统大规模组网面临的顽疾。在总结分析大气波导干扰成因和分类等的基础上，对大气波导干扰进行建模和表征，验证了海量干扰源在时域和频域的功率集总特征，并结合大量4G/5G现网实测数据给出了典型条件下内陆波导和海面波导的量化干扰信号传播模型，对于干扰的预测和预防具有重要意义。基于干扰特征，给出了TDD系统预防大气波导干扰的帧结构与组网的4项设计原则，5G现网数据表明干扰控制方案有效，上行干扰下降10 dB以上，相关原则对于6G系统的设计也具有指导意义。     

Thermo-adjusted self-healing epoxy resins based on Diels–Alder dynamic chemical reaction

Micro-damage in materials could be repaired by endowing materials with self-healing performance. Herein, an epoxy resin with excellent self-healing performance grounded on thermo-reversible Diels–Alder dynamic chemical reaction was developed. Results showed that the bending strength and adhesive behavior of epoxy resin were influenced dramatically upon treatment with various temperatures. More importantly, damages created in epoxy resin could be repaired completely after suitable heat treatments. What is more, the healed epoxy resin exhibited much higher bending strength and adhesive performance than the pristine one did. The materials could be damaged and then repaired repeatedly. Meanwhile, the as-prepared self-healing epoxy resin exhibited excellent thermal reversibility and controllable adhesion. The thermo-adjusted self-healing performance endowed epoxy resin with recyclable and reusable performance. Therefore, the research made it possible of recycling waste epoxy resins.     

Autonomic Nervous System in Obesity and Insulin-Resistance—The Complex Interplay between Leptin and Central Nervous System

The role of the autonomic nervous system in obesity and insulin-resistant conditions has been largely explored. However, the exact mechanisms involved in this relation have not been completely elucidated yet, since most of these mechanisms display a bi-directional effect. Insulin-resistance, for instance, can be caused by sympathetic activation, but, in turn, the associated hyperinsulinemia can activate the sympathetic branch of the autonomic nervous system. The picture is made even more complex by the implicated neural, hormonal and nutritional mechanisms. Among them, leptin plays a pivotal role, being involved not only in appetite regulation and glucose homeostasis but also in energy expenditure. The purpose of this review is to offer a comprehensive view of the complex interplay between leptin and the central nervous system, providing further insights on the impact of autonomic nervous system balance on adipose tissue and insulin-resistance. Furthermore, the link between the circadian clock and leptin and its effect on metabolism and energy balance will be evaluated.     

A robust model-free controller for a three-phase grid-connected photovoltaic system based on ultra-local model

In this paper, a robust model-free controller for a grid-connected photovoltaic (PV) system is designed. The system consists of a PV generator connected to a three-phase grid by a DC/AC converter. The control objectives of the overall system are to extract maximum power from the PV source, to control reactive power exchange and to improve the quality of the current injected into the grid. The model-free control technique is based on the use of an ultra-local model instead of the dynamic model of the overall system. The local model is continuously updated based on a numerical differentiator using only the input–output behavior of the controlled system. The model-free controller consists of a classical feedback controller and a compensator for the effects of internal parameter changes and external disturbances. Simulation results illustrate the efficiency of the controller for grid-connected PV systems.     

面向老龄化社会的产品服务系统设计赋能

目的 针对面向老龄化社会的产品及产品服务系统设计,将赋能的设计理念和价值引入其中,探索设计结果提升老年人能动性和参与性的赋能品质,为设计师开展设计赋能实践提供参考.方法 以设计教学中的学生设计方案作为研究材料,邀请设计研究者参与工作坊,对设计结果的赋能属性进行分析,并通过聚类获得类别化的设计属性,产生了能描述赋能品质的属性词汇表.结果 总结了包含5组形容词组的设计赋能品质集,这一集合包含"顺应性"和"激励性"两个面向.结论 研究结果为设计师进行老龄化设计提供了知识参考,有助于提升设计师的赋能意识.揭示了设计赋能充满矛盾性的品质,提出面向老龄化的设计赋能需要在"顺应"和"激励"之间找到平衡.     

Recent advances during CH4 dry reforming for syngas production: A mini review

Given the continuing issues of environment and energy, methane dry reforming for syngas production have sparked interest among researchers, but struggled with the process immaturity owing to catalyst deactivation. This review summarizes the recent advances in the development of efficient and stable catalysts with strong resistance to coking and metal sintering, including the application of novel materials, the assessment of advanced characterizations and the compatibility to improved reaction system. One feasible option is the crystalline oxide catalysts (perovskite, pyrochlore, spinel and LDHs), which feature a fine metal dispersion and surface confinement effect via a metal exsolution strategy and exhibit superior reactivity and stability. Some new materials (h-BN, clays and MOFs) also extend the option because of their unique morphology and microstructure. It also is elaborated that progresses were achieved in advanced characterizations application, leading to success in the establishment of reaction mechanisms and attributions to the formed robust catalysts. In addition, the perspective described the upgrade of reaction system to a higher reaction efficiency and milder reaction conditions. The combination of efficient reaction systems and robust catalysts paves a way for a scaling-up application of the process.     

宰前倒挂应激对鸭血凝胶特性的影响

宰前倒挂因能有效提高屠宰效率成为肉鸭宰杀前必经的一个工艺过程，但倒挂往往会加剧肉鸭的应激程度，影响其血液品质，已成为工厂生产中亟待解决的问题。因此，本实验旨在借助血液学与凝血相关指标探究宰前倒挂应激对鸭血凝胶特性的影响。在屠宰前，将40 只樱桃谷鸭随机分为2 个处理组：对照组和宰前倒挂组（宰前倒挂2.5 min），屠宰后采集血样并制备血凝块，随后分析血液指标（应激指标、血液学指标、凝血指标）以及鸭血凝胶特性。结果表明，宰前倒挂组鸭血中皮质酮激素及促肾上腺皮质激素的水平均高于对照组，说明实验所建立宰前倒挂模型成立。倒挂应激后，红细胞计数、血小板计数、血红蛋白质量浓度增加，红细胞比容、平均红细胞体积及平均血小板体积增大；凝血酶原的水平极显著上升（P＜0.01），组织因子的水平显著上升（P＜0.05）。宰前倒挂最终导致鸭血凝胶化加快，鸭血凝胶体系中水分迁移速率增大，结合水与自由水比例减少，不易流动水比例增大，质构特性和保水性变差。研究揭示了宰前倒挂应激通过影响鸭血的血液学指标和凝血系统从而改变其凝胶行为及凝胶特性，可为工厂改善应激对鸭血凝胶品质的影响提供理论依据。