Carbon Black-Supported Single-Atom Co?N?C as an Efficient Oxygen Reduction Electrocatalyst for H2O2 Production in Acidic Media and Microbial Fuel Cell in Neutral Media

Single metal atom isolated in nitrogen-doped carbon materials (M N C) are effective electrocatalysts for oxygen reduction reaction (ORR), which produces H₂O₂ or H₂O via 2-electron or 4-electron process. However, most of M N C catalysts can only present high selectivity for one product, and the selectivity is usually regulated by complicated structure design. Herein, a carbon black-supported Co N C catalyst (CB@Co N C) is synthesized. Tunable 2-electron/4-electron behavior is realized on CB@Co-N-C by utilizing its H₂O₂ yield dependence on electrolyte pH and catalyst loading. In acidic media with low catalyst loading, CB@Co N C presents excellent mass activity and high selectivity for H₂O₂ production. In flow cell with gas diffusion electrode, a H₂O₂ production rate of 5.04 mol h⁻¹ g⁻¹ is achieved by CB@Co N C on electrolyte circulation mode, and a long-term H₂O₂ production of 200 h is demonstrated on electrolyte non-circulation mode. Meanwhile, CB@Co N C exhibits a dominant 4-electron ORR pathway with high activity and durability in pH neutral media with high catalyst loading. The microbial fuel cell using CB@Co N C as the cathode catalyst shows a peak power density close to that of benchmark Pt/C catalyst.     

钛合金表面激光重熔镍包石墨涂层的研究

为了提高钛合金的表面耐磨性能,以镍包石墨粉末作为预涂材料,先热喷涂到Ti-6A l-4V基底表面,再采用激光技术进行重熔处理,获得了质量良好的增强涂层。通过XRD、SEM和EDS对涂层组织进行分析,结果表明:涂层的微观组织为固熔了少量Ti元素的镍基,含有大量的TiC增强相。这些TiC增强相呈现发达的枝晶状形态,是在激光重熔过程中原位反应生成的。显微维氏硬度测试表明:激光重熔涂层的硬度达到HV1200,是钛合金基底硬度的3倍。     

500kW／380V国产大功率变频器在钻机上的应用

针对国外变频器价格昂贵、调试周期和维修周期长等特点，我公司自主研发了可替代进口机的高性能钻机国产专用变频器。该变频器能够从零开始调速。当钻井卡钻时，能及时断开电动机，在低速提升时，能最大限度地发挥电动机的动力特性，提供220％的转矩输出。变频器具有易安装、调试、维护，性能稳定。应用中据实测数据显示，采用变频改造后，打1口井可节省柴油15t。     

Compensation of phase noise in OFDM systems using an ICI reduction scheme

In Orthogonal Frequency Division Multiplexing (OFDM) communication systems, the local oscillator phase noise introduces two effects: common phase error (CPE) and inter-carrier interference (ICI). The correction of CPE does not suffice always, especially when high data rates are required. Through the creation of a frequency-domain linearized parametric model for phase noise, we generate an ICI reduction scheme to deal with phase noise. The effects of the transmitter high-power-amplifier (HPA) nonlinearity on the phase noise compensation are also investigated. The algorithm performance over AWGN channel is presented for DVB-T 2k and 8k modes. It is shown by the simulation results that the algorithm can significantly reduce the symbol-error rate (SER) floor, caused by the residual phase noise after CPE correction, while sacrificing an acceptable transmission bandwidth.     

PCB热变形的实时干涉测量研究

采用二次曝光和实时全息干涉技术对某一PCB进行了实验测试,获得了不同功率和不同夹持条件下PCB表面的离面位移分布以及离面位移随时间的动态变化图象。对两种不同的条纹图像进行处理,结果表明,随功率的增大,器件的离面翘曲量增大;在不同夹持条件下,由于器件局部受力约束和热传导条件的差异,呈现不同的位移分布,电阻区(热源区)附近的离面翘曲量变化较快而且较大。     

会话边缘控制器关键技术实现

通过对会话边缘控制器(SBC)及相关的SIP协议、网络地址转换/防火墙、媒体处理、拓扑隐藏及协议修改技术的说明,给出了SBC的核心模块的设计原型,并对信令代理和媒体代理关键子模块进行了设计实现说明。采用B2 BUA、状态机、SIP/RTP/RTCP消息修改、地址映射、回调函数、媒体流处理、服务质量(QoS)控制策略等技术,对系统做了具体实现。测试结果表明,系统具备了作为一个SBC的功能。     

穿戴式生理检测设备电源设计

介绍了三种典型的稳压电源,结合穿戴式生理检测设备电源管理的特点,分析了电路低功耗设计和电源保护的关键技术,提出了一种基于低压差线性稳压电源MAX8881、无线充电接收器BQ51013和自恢复保险丝的电源设计实例。     

雪崩光电管两种应用方式分析

通常有两种方式可以实现用噪声来调节雪崩管的偏压。本文首先建立了几个能衡量这种调节作用的效果的指标。通过比较两种调节方式的各项指标,指出各种条件下两种方式的优劣。     

雷达发射机高电压绝缘的分析和实践

根据分子运动理论对真空管雷达发射机中高压引起的放电、打火、击穿的过程和因素进行分析,并根据工程实践经验给出高压电源及高压变压器研制时的注意事项,对各种真空管发射机的设计有普遍意义。     

基于SOA和云技术的论文网络投稿系统初探

随着互联网技术的推广与普及,从高校论文管理水平和论文编审效率的角度出发,建立网络投稿系统已成为必然趋势。本文对论文网络投稿系统的需求进行了详细分析,并对在系统设计技术上采用SOA、云计算技术进行了探索。