内存映射文件及其在广义舒适度仿真中的应用

本文分析了win32系统下的虚拟内存系统模式及内存映射文件的工作机理,介绍了如何用windows API将文件映射至内存,利用原型页表入口技术实现了多个进程之间的数据共享。通过实验数据得出,采用内存映射文件读取高速服役列车的广义舒适度仿真中的超大数据文件,其效率远远高于传统的基于文件I/O方式的数据存取。     

纳米非晶态Ni(OH)_2电极材料的稀土掺杂改性研究

为了提高镍基二次电池正极材料的电化学性能,采用微乳液快速冷冻沉淀法制备出稀土Ce掺杂纳米级非晶态氢氧化镍粉体材料.采用Raman,XRD,SEM和TEM对其结构形态进行了表征分析,采用交流阻抗谱(EIS)和充放电性能对其电化学性能进行了测试.结果发现,掺入适量的Ce可以进一步增强纳米非晶态氢氧化镍的无序性并且使颗粒细化,进而使其电化学反应的电荷转移电阻降低,电化学活性明显增强.样品作为MH-Ni电池正极材料以0.2 C充放电,终止电压为1.0 V,当掺杂Ce的质量分数为4%时,其放电比容量达到336.7 mAh/g,这明显高于晶态β-氢氧化镍电极材料289 mAh/g的理论容量,说明纳米非晶态氢氧化镍作为高活性电极材料具有很好的应用前景.     

Al_2O_3颗粒对Al-Zn合金激光快凝组织的影响

通过比较Ａｌ－Ｚｎ合金和Ａｌ_２Ｏ_（３ｐ）／Ａｌ－Ｚｎ复合材料的激光重熔组织。分析Ａｌ_２Ｏ_３颗粒对Ａｌ－Ｚｎ合金激光快凝组织的影响规律。实验结果表明,Ａｌ_２Ｏ_３颗粒可以显著细化激光熔区的晶粒。基于凝固界面与颗粒交互作用的理论分析,给出了晶粒细化的临界条件。     

快速成功实施农村数字电视整体转换的策略

结合海安农村地区数字电视整体转换的实践,简要介绍有线电视数字化整体转换的体会,提出一些如何在农村地区快速、成功实施整体转换的策略。     

贴片机X/Y轴快速高精度定位的实现

负载惯量和外界干扰是影响贴片机X,Y轴快速高精度定位的两个关键因素。本文针对负载惯量和外界干扰对控制性能的影响,提出了基于RBF神经网络的自适应滑模控制算法。利用RBF神经网络的万能逼近特性实现对外加干扰和被控对象模型信息的逼近,运用自适应控制算法计算前馈补偿量以补偿负载惯量和摩擦力对运动性能的影响,采用滑模控制算法以抑制其他不确定干扰对运动控制的影响。通过仿真分析可以得出,所采用的控制算法能够有效地补偿负载惯量和外界干扰对定位性能的影响,从而实现贴片机X,Y轴的快速高精度定位。     

Post-process thermal treatment for microwave power improvement of AlGaN/GaN HEMTs

The effects of post-process rapid thermal annealing (RTA) treatment after device fabrication on direct current, microwave and power performances of AlGaN/GaN high electron mobility transistors (HEMTs) with a gate-length of 0.2 μm were fully investigated. By 3 min post-process RTA treatment at 350 °C under N₂ atmosphere, the direct current (DC), radio frequency (RF) small signal and power performances of AlGaN/GaN HEMTs have been much improved. The output power, power gain and power added efficiency (PAE) of GaN HEMT device with gate wide of 1 mm increase from 37.09 dBm, 6.09 dB and 42.79% to 38.22 dBm, 7.22 dB and 67.3%. The post-process RTA after device fabrication has two merits. On the one hand, it improves passivation effect of SiN_x dielectric layer on AlGaN/GaN HEMT surface, suppressing RF current dispersion. On the other hand, it helps recover dry-etch damage at the Schottky metal/AlGaN interface, leading to reduction of reverse Schottky leakage current.     

一种高精度快速响应欠压锁定电路设计

针对传统欠压锁定(UVLO)电路结构复杂和响应速度慢的问题,设计了一种高精度的快速响应欠压锁定电路.该电路整体均由CMOS管组成,结构简单且易于实现.采用电流模控制技术,随电源电压呈二次方曲线变化的自偏置电流控制阈值电压的产生,有效提高了电路的响应速度.该欠压锁定电路基于0.18μm BCD工艺设计,并利用HSPICE进行仿真验证,当电源电压在0～5V区间变化时,输出电压翻转的上阈值门限为3.91 V,相应下阈值门限为3.82V,迟滞量为90 mV,温度在-40～125℃范围变化时,阈值门限电压容差仅为0.9μV,可实现输出电压的高精度转换,电路面积仅为15 μm×48μm.     

一种快速同步的时钟数据恢复电路的设计实现

时钟数据恢复(CDR)电路是通信传输设备中的重要部分,对于突发式的接收,基于锁相环的传统的CDR往往不能满足其快速同步的要求.对此,文章采用过采样方式基于FPGA设计实现了一种全数字化的155.52Mb/s下的CDR电路.理论分析、仿真和实验测试结果表明,该CDR电路可以有效地对相位变化实现快速同步,有很大的捕捉范围,且系统较锁相环便于集成.     

Sustainable 3D Structural Binder for High-Performance Supercapacitor by Biosynthesis Process

Flexible supercapacitors represent an attractive technology for the next generation of wearable consumer electronics as power sources but usually suffer from relatively low energy density. It is highly desired to construct high-performance electrodes for the practical applications of supercapacitors. Here, inspired by the natural structure of the spider web, an elaborate design of binder is reported through a biosynthesis process to construct flexible electrodes with both excellent mechanical properties and electrochemical performance. Through this strategy, a spider-web-inspired 3D structural binder enables large ion-accessible surface area and high packing density of active electrode material as well as efficient ion transport pathways. As a result, a high areal capacitance of 4.62 F cm^-2 and a high areal energy density of 0.18 mW h cm^-2 is achieved in the composite electrodes and symmetric supercapacitors, respectively, demonstrating a promising potential to construct flexible energy storage devices for diverse practical applications.     

A Novel Magnetic Hardening Mechanism for Nd-Fe-B Permanent Magnets Based on Solid-State Phase Transformation

Permanent magnets based on neodymium-iron-boron (Nd-Fe-B) alloys provide the highest performance and energy density, finding usage in many high-tech applications. Their magnetic performance relies on the intrinsic properties of the hard-magnetic Nd₂Fe₁₄B phase combined with control over the microstructure during production. In this study, a novel magnetic hardening mechanism is described in such materials based on a solid-state phase transformation. Using modified Nd-Fe-B alloys of the type Nd₁₆Fe_bal-x-y-zCo_xMo_yCu_zB₇ for the first time it is revealed how the microstructural transformation from the metastable Nd₂Fe₁₇B_x phase to the hard-magnetic Nd₂Fe₁₄B phase can be thermally controlled, leading to an astonishing increase in coercivity from ≈200 kAm⁻¹ to almost 700 kAm⁻¹. Furthermore, after thermally treating a quenched sample of Nd₁₆Fe₅₆Co₂₀Mo₂Cu₂B₇, the presence of Mo leads to the formation of fine FeMo₂B₂ precipitates, in the range from micrometers down to a few nanometers. These precipitates are responsible for the refinement of the Nd₂Fe₁₄B grains and so for the high coercivity. This mechanism can be incorporated into existing manufacturing processes and can prove to be applicable to novel fabrication routes for Nd-Fe-B magnets, such as additive manufacturing.