单周期功率因数校正的研究

分析了单周期功率因数校正(PFC)控制原理,使用Matlab软件对单周期控制进行建模和仿真,制造出一台基于单周期前沿调制芯片ICE2PCS02的300W原理样机,实验结果和仿真结果有较好的吻合,证明单周期PFC可以在使用较少元器件情况下很好的完成功率因数校正,且动态响应快,功率因数高,为实际使用带来了极大的方便.     

移动互联网环境下SIP穿越 NAT的研究

NAT （Network Address Translation）穿越问题是制约SIP（Session Initiation Protocol ）发展的主要障碍之一。分析了ICE（Interactive Connectivity Establishment ）方式协助SIP穿越NAT的机制,并根据移动互联网环境的特点对ICE作了进一步改进,最后把改进的ICE作为一个模块成功嵌入到了Android VoIP软件之中。实验证明改进的ICE可使SIP穿越任何NAT ,且有成功率高、低时延的优点,非常适用于移动互联网环境。     

Effect of different volume fractions of ammonia on the combustion and emission characteristics of the hydrogen-fueled engine

Hydrogen internal combustion engines (ICE) will play an important role in reducing carbon emissions, but low power density and abnormal combustion problems are the main obstacles restricting the promotion of hydrogen ICE. Ammonia is a low-reactivity renewable fuel. The purpose of this study is to study the effect of different ammonia-added volume fractions on hydrogen ICE. In this experimental study, the combustion and emission characteristics of an engine fueled by a hydrogen/ammonia mixture were evaluated at part-load operating conditions. The experiment was carried out on a modified engine, the engine speed was 1300 rpm, the absolute pressure of the manifold was 61 kPa, and the volume fraction of ammonia added was 5.2%, 7.96%, and 10.68%, respectively. The test results show that the addition of ammonia changes the combustion characteristics of hydrogen. As the volume fraction of ammonia added increases, the flame development period and flame propagation period are both prolonged, and the peak heat release rate decreases. The addition of ammonia increases the power of the engine and reduces the indicated thermal efficiency. At the ignition timing of the maximum braking torque, as the volume fraction of ammonia added increases, the indicated mean effective pressure and indicated thermal efficiency increase. Adding ammonia volume fraction has little effect on Nitrogen oxides (NOx) emissions, and NOx emissions gradually increase with the delay of ignition timing.     

Veloce平台在大规模SOC仿真验证中的应用

随着现代集成电路技术的发展,尤其是IP的大量使用,芯片的规模越来越大,系统功能越来越复杂,普通的EDA和FPGA仿真在速度和性能上已经无法胜任芯片仿真验证的要求,功能验证已经成为大规模芯片设计的一个瓶颈;同时复杂的SOC系统需要相应的软件,由于芯片研发的周期越来越长,传统的软硬件顺序开发的方式受到了市场压力的巨大挑战,软硬件并行开发成为将来大规模Ic系统设计的一大趋势。本文主要介绍Mentor Graphics公司Veloce验证平台在超大规模IC系统中仿真验证的应用。借助Veloce的高速和大容量的特性,极大的提高功能验证的效率,解决由于芯片规模大FPGA无法验证的问题,保证芯片的按时投片。同时通过和Jtag的联合使用,成功解决软硬件的联合仿真和并行开发。     

Comparative exergy analyses of gasoline and hydrogen fuelled ICEs

Comparative exergy models for naturally aspirated gasoline and hydrogen fuelled spark ignition internal combustion engines were developed according to the second law of thermodynamics. A thorough analysis of heat transfer, work, thermo mechanical, and chemical exergy functions was made. An irreversibility function was developed as a function of entropy generation and graphed. A second law analysis yielded a fractional exergy distribution as a percentage of chemical exergy of the intake. It was found that the hydrogen fuelled engine had a greater proportion of its chemical exergy converted into work exergy, indicating a second law efficiency of 41.37% as opposed to 35.74% for a gasoline fuelled engine due to significantly lower irreversibilities and lower specific fuel consumption associated with a hydrogen fuelled ICE. The greater exergy due to heat transfer or thermal availability associated with the hydrogen fuelled engine occurs due to a greater amount of convective heat transfer associated with hydrogen combustion. However, this seemingly high available thermal energy or thermal ‘exergy’ is misleading due to the higher cooling load which decreases the power of a hydrogen fuelled ICE. Finally, a second law analysis of both hydrogen and gasoline combustion reactions indicate a greater combustion irreversibility associated with gasoline combustion. A percentage breakdown of the combustion irreversibilities were also constructed according to information found in literature searches.     

嵌入式系统调试方法的分析与比较

调试是嵌入式系统开发过程中必不可少的重要环节,它占整个开发时间的20%～50%.本文对常用的调试方法进行了介绍,分析与比较了调试方法及其调试工具的特点,为在不同条件下选择合适的调试工具提供了参考,有助于嵌入式系统调试性能的提高.     

RFID电子标签地址和安全逻辑设计

介绍了RFID电子标签地址和逻辑安全的基本架构,给出了详细的状态机和加密部件的设计框图。本设计适用于符合ISO/ICE 15693标准的RFID电子标签的数字部分。     

基于数字鉴频器的内燃机瞬时转速延时测量法

将基于数字鉴频器的延时法用于内燃机瞬时转速测量．首先介绍了延时法解调电路原理，然后使用仿真手段对延时法测量的特点进行了研究．仿真结果表明，该方法能够较好地还原频率调制信号，最后经实测试验证明了测量的有效性．该方法可采用全硬件电路实现，测量设备简单，可抑制调幅因素的影响，是一种有效的瞬时转速测试方法．     

一种带有流水线追踪器的JTAG ICE调试电路设计

针对复旦大学自主开发的32位RISCCPU,设计了相应JTAG调试电路(In—Circuit Emulator)。为解决此RISCCPU中5级流水线导致的断点误停的问题,提出了一种新颖的带有分支预测功能的电路结构一“流水线追踪器”。此JTAG调试电路与IEEE1149．1标准兼容,具有设置断点、单步、查看或修改CPU寄存器／内存空间、在线FLASH编程等多种功能。     

四缸内燃机振动分析及其对策

四缸内燃机主要存在2阶振动,通过测取不同工况下的示功图,研究四缸内燃机的倾覆力矩和往复惯性力及其力矩的2阶谐量在工况平面上的分布特性,提出了双轴平衡理论,分别对于3类发动机,特别是车用发动机提出了具体实用对策,能够同时完全平衡,或者部分平衡2阶气体不平衡力矩、惯性力和惯性力矩,并以振动较恶劣的车用柴油机为算例,研究不同工况下平衡轴所产生的平衡效果。