Efficient design and hardware implementation of a secure communication scheme for smart grid

In smart grid, bidirectional communications between the smart meters and control center are subject to several security challenges. Since the smart meters have limited storage space and processing capability, the suggested communication scheme not only must consider the security requirements but also should put the least possible burden on the smart meters' resources. In 2014, an interesting communication scheme has been proposed for the secure consumption reports transmission of the smart meters to the neighbor gateways. In this paper, we first show that this scheme is vulnerable to the smart meter's memory modification, pollution, and denial of service attacks; then, we propose an authenticated communication scheme, which not only is secure against the aforementioned attacks, but also is much more efficient in terms of storage space, communication overhead, and computational complexity. Moreover, our scheme also presents the details of control messages transmission from the neighborhood gateways to the smart meters. Our comparative analysis with several recently published schemes indicates that the proposed scheme is more suitable than the previous ones. More significantly, our realistic implementation on ATmega2560, as a suitable candidate to be used for the smart meters, confirms our claim.     

内置驱动器的六位GaAs PHEMT宽带单片数控衰减器

采用增强/耗尽型(E/D)结构的赝配高电子迁移率晶体管(PHEMT)技术,研制开发的砷化镓MMIC单片六位数字控制衰减器,具有衰减精度准确、承受功率大、线性度高等特点,并且集成了驱动器,使得输入信号控制线减少了一半,大大减少了系统布线的难度。产品由GaAsPHEMT标准工艺线加工。测试结果表明,在0.05～3.0GHz带内,插入损耗≤2.3dB@3GHz,带内输入输出驻波比≤1.5,衰减精度在±(0.3dB+3%)以内,1dB压缩功率点达到了27dBm,IP3超过了+45dBm。     

智能语音报警温度计的设计

基于MCU LPC2138和数码语音芯片ISD1420接口技术,设计并研制出了一种新型集语音报告、报警功能于一体,并同时显示温度变化曲线的智能温度计.对该温度计的电路原理图、硬件电路和语音报告程序实例进行了介绍.     

基于ISD4004语音芯片的语言学习机的设计

本文给出了采用ISD4004语音芯片的一种语言学习机的应用电路。重点介绍其接口原理和实现方法，及如何实现语言学习机所要求的暂停及自动断句等功能。     

宽带GaAs MESFET开关模型

提出了一种 MESFET开关的模型——附加栅控开关模型 ,适用于 MMIC电路的设计 ,具有很好的宽带微波特性。在 0 .1～ 2 0 GHz频率范围内 ,器件测试值与模型模拟值吻合较好     

The process of enterprise resource planning implementation and business process re-engineering: tales from two Chinese small and medium-sized enterprises

Abstract.  Using an innovative process model, we describe and analyse the process of introducing enterprise resource planning (ERP) systems in two Chinese small and medium-sized enterprises and especially their decisions concerning business process re-engineering. First we compared the results from our cases with Martinsons' earlier work (2004). One case seemed to fit most of the characteristics of a private venture (PV) whereas the other case, also a PV, had a very low degree of fit. We used the process model to offer further insights and features such as its predictive power. Second, and as predicted, we also observed the differential role of top management support in the two Chinese companies. But thirdly, and somewhat surprisingly, we found that cultural issues were only of limited importance. Finally, the ability of the project team to deal with unexpected events was seen as critical in ensuring the stability of a project. In contrast, project drift is shown to lead to a degree of chaos. We offer some suggestions as to how stakeholders can improve their chances of implementing ERP systems more successfully.     

ISD2560芯片在汽车报站器的应用

介绍了一种新型汽车报站器的工作原理。提出了由8031单片机控制的的语音控制电蓐和LED汉字显示站名电路的硬件设计和软件设计方案．该系统和目前的自动报站系统相比，语音音质好，功能强，是提供公交服务的一种很好的手段．     

基于51单片机的语音提示饮水杯的设计

针对实现语音提示饮水杯的语音提示装置的录音,定时和回放的目的,采用以C编写程序,设计电路的软件部分和以AT89C51单片机为核心,连同ISD2500系列语音芯片和其他元器件,设计电路的硬件部分的软硬件相结合的方法。即软件部分:在KEIL环境中编写并验证C程序。硬件部分:在语音提示盖顶部设有3个按键:开/关按钮、录/放音按钮、定时按钮,并同时伴有录音孔、扬声器孔、LED录音指示灯。启动语音装置后,录下想要提示的录音;设置时间后,到时即可播放录音。通过语音提示饮水杯的录音,定时和回放实验,该设计完全可以满足要求。     

ISD语音芯片应用开发环境的设计与实现

介绍了在Windows 98平台上开发的ISD系列语音芯片应用开发环境 :由微机、声卡、调试板组成ISD的开发装置 ,采用VC 6 0编程 ,在各模块的协调作用下完成对语音芯片的开发 .它不仅能确定语音段在存储器中的精确地址 ,还可显示语音信息的存储情况 ,其特有的声音特效处理机制也便于应用产品的开发     

基于无线射频识别技术的公交车自动报站系统

现在国内普遍采用的手动公交车报站系统经常出现人为错误,给市民出行和公交车运行带来许多不便。针对此问题,将无线射频识别技术、单片机控制技术、数字语音技术、发光二极管(LED)显示技术相结合,设计了一种新型自动报站系统,并给出了该系统的总体结构和软硬件设计。该系统结构简单易行,实现了公交报站的智能化,降低了驾驶员的工作难度,提高了公交车运行的安全性及报站的准确性,具有较强的实用价值及广泛的应用前景。