MQAM调制器的设计与实现

文中提出了一种多电平正交振幅调制器(MQAM)的设计与实现方法。该调制器由纠错编码部分、脉冲成形滤波器和混频器构成。实践证明,本设计可在单片FPGA中实现DAVIC协议中所建议的MQAM(M=16,64,256)调制器。该设计可在数字电视机顶盒(STB)内作为实现交互电视(iTV)的主体功能模块,具有较高的实用价值。     

四川盆地及周缘志留系龙马溪组一段深层页岩储层特征及其成因

深层页岩储层是页岩气勘探开发的重要接替领域.针对四川盆地及周缘龙马溪组一段深层页岩,系统开展了X-衍射全岩(XRD)、总有机碳(TOC)、大薄片及氩离子抛光大片成像研究.结果表明,相对于浅层页岩,深层页岩储层具有高硅质和低TOC含量、低粉砂纹层含量、高孔隙度和更有效的孔隙网络特征.由浅层至深层,页岩硅质含量由30％增至...     

An Overview of Virtual Private Network (VPN): IP VPN and Optical VPN

Recently, there has been rapid development and deployment of virtual private network (VPN) services. There are wide varieties of IP-based VPNs and optical VPNs (OVPNs) proposed in the literature and readers could easily get confused with so many different types of VPNs. The purpose of this paper is to present a comprehensive overview of the VPN and discuss the main issues associated with the design of IP VPN and OVPN. We first present a classification of the VPNs including CE-based, network based, customers provisioned, provider provisioned, connection oriented, connectionless oriented, port based, connection based, layer 1 VPN, layer 2 VPN, and layer 3 VPN, and describe different VPN protocols such as IPSec, GRE and MPLS. We then review the recent work on OVPN by different standard bodies, and outline the key requirements for OVPN service providers and customers. Finally, we describe several OVPN architectures appeared in the literature, highlight the future work in OVPN.     

提高电容器D值测量准确度的方法

本文就阻抗测量中Ｄ值测量的几种方法进行了比较，着重介绍了目前发展最快的Ｉ－Ｖ法的测量原理、理论和实验证实附加一个偏置电容，大大提高了Ｄ值测量的准确度。     

多通道控制／检测操纵台

本操纵台可以对６４个通道或号位的综合参数，如温度、压力、温度、物位、流量等刊物民检测，它具有两种功能；（１）对６４个地点的进行自动巡回控制／检测；（２）可随意对任意地的参数进行优化控制／检测。     

组合梁钢框架抗震性能研究综述

本文详细介绍了国内外组合梁钢框架结构抗震性能研究的情况，并指出了今后的研究重点及方向。     

故障诊断专家系统的开发策略研究

故障诊断专家系统研究已形成一个独立的研究领域，但关于系统的建造尚未形成具有自身特点的系统理论和科学的方法体系。本文首先分析了故障诊断专家系统所具备的功能和特点，在此基础上提出了故障诊断专家系统的一般结构，并阐述了各模块的功能。最后结合作者的实际工作，提出了各模块的一些具体的开发策略。     

激光对不同物质消融的研究

本文报道了用308nm XeCl激光消融聚合物及生物组织和角膜刻划的研究结果,并与1.06μm和0.53μm的纳秒、皮秒YAG激光消融生物组织的结果作了对比。     

光纤气管明视镜的研制

将自聚焦透镜和光纤面板复丝棒首次用于医疗内窥镜,研制成一种气管镜絲辅助装置——光纤气管明视镜。经第四军医大学进行动物试验证明:本装置具有空间小、分辨率高,能使照明、观察和操作同步等优点。     

Rational Design and General Synthesis of S‐Doped Hard Carbon with Tunable Doping Sites toward Excellent Na‐Ion Storage Performance

Heteroatom‐doping is a promising strategy to tuning the microstructure of carbon material toward improved electrochemical storage performance. However, it is a big challenge to control the doping sites for heteroatom‐doping and the rational design of doping is urgently needed. Herein, S doping sites and the influence of interlayer spacing for two kinds of hard carbon, perfect structure and vacancy defect structure, are explored by the first‐principles method. S prefers doping in the interlayer for the former with interlayer distance of 3.997 Å, while S is doped on the carbon layer for the latter with interlayer distance of 3.695 Å. More importantly, one step molten salts method is developed as a universal synthetic strategy to fabricate hard carbon with tunable microstructure. It is demonstrated by the experimental results that S‐doping hard carbon with fewer pores exhibits a larger interlayer spacing than that of porous carbon, agreeing well with the theoretical prediction. Furthermore, the S‐doping carbon with larger interlayer distance and fewer pores exhibits remarkably large reversible capacity, excellent rate performance, and long‐term cycling stability for Na‐ion storage. A stable and reversible capacity of ≈200 mAh g^?1 is steadily kept even after 4000 cycles at 1 A g^?1.