Experimental investigation of liquid water in flow field of proton exchange membrane fuel cell by combining X-ray with EIS technologies

The flow field is a pivotal part to manage the transport of water and gas in proton exchange membrane fuel cell. However, the reported water measurement methods (e.g., X-ray and electrochemical impedance spectroscopy (EIS)) cannot give a comprehensive understanding water distribution in the flow field, resulting in challenges in optimizing the channel design and enhancing fuel cell performance. Therefore, we propose a water measurement method combining the X-ray radiography with EIS to investigate the effect of different operating conditions on the growth law and distribution of liquid water in parallel and serpentine flow fields. The attenuation coefficient of liquid water to X-ray is calibrated with constant tube-current and tube-voltage of X-ray generator. Besides, the parallel flow field with hydrophobic treatment is studied. The results show that the water accumulation of the parallel flow field is far more than the serpentine flow field, and the water content of the middle region is higher than that of other regions in the parallel flow field. Furthermore, operating conditions (cathode inlet gas flow rate, inlet gas humidity, and back pressure) have little effect on the liquid water content of the middle region in the parallel flow field. The polarization curve, EIS result, and X-ray radiography show that the performance and water drainage capacity of the hydrophobic parallel flow field are better than the normal one.

     

Cryptanalysis of RSA for a special case with d > e

In this paper, we study the RSA public key cryptosystem in a special case with the private exponent d larger than the public exponent e. When N ^0.258 ⩽ e ⩽ N ^0.854, d > e and satisfies the given conditions, we can perform cryptanalytic attacks based on the LLL lattice basis reduction algorithm. The idea is an extension of Boneh and Durfee’s researches on low private key RSA, and provides a new solution to finding weak keys in RSA cryptosystems. Supported partially by the National Basic Research Program of China (Grant No. 2003CB314805), the National Natural Science Foundation of China (Grant Nos. 90304014 and 60873249), and the Project funded by Basic Research Foundation of School of Information Science and Technology of Tsinghua     

Cryptanalysis of RSA for a special case with d>e

In this paper,we study the RSA public key cryptosystem in a special case with the private exponent d larger than the public exponent e. When N0.258 e N0.854,d > e and satisfies the given conditions,we can perform cryptanalytic attacks based on the LLL lattice basis reduction algorithm. The idea is an extension of Boneh and Durfee's researches on low private key RSA,and provides a new solution to finding weak keys in RSA cryptosystems.     

Comparing two sets without disclosing them

Secure multiparty computation has become a central research focus in the international cryptographic community. Secure comparing two sets is an important problem in secure multiparty computation. The research on privately determining whether two sets are equal has not been investigated. This study solves the problem by mapping these sets into natural numbers and then comparing correspond- ing numbers, We propose two secure multiparty computation protocols for comparing two sets. It is proved by well-accepted simulation paradigm that these solutions are private in semi-honest model. These solutions have important significance in constructing other secure multiparty computation protocols.     

时代集团公司辉煌2005

1、公司总裁被授予2004年度全国机械工业优秀企业家称号 2005年3月，王小兰总裁被授予“2004年度全国机械工业优秀企业家”称号。此次评选活动由中国机械上业联合会从2002年发起，在全行业开展，对在振兴机械工业中作出突出贡献的机械：亡业优秀企业家进行表彰。     

A SiGe HBT low noise amplifier using on-chip notch filter for K band wireless communication

In this paper a new notch filter topology has firstly been described. In order to improve the input match as well as enhance the gain on the operating frequency of 20.5 GHz, extra capacitor has firstly been added in the passive base-collector notch filter forming a new scheme, eliminating the operating-frequency (op) input mismatch in formal base-collector notch filters. EM simulations have shown that the LNA obtained 14.1 dB gain at 20.5 GHz and high image-rejection ratio (IRR) of 33.5 dB at image frequency of 15 GHz, and S₁₁ of -15 dB was obtained compared to −8 dB without notch filter at operating frequency, NF was below 5 dB at gain peak frequency, power consumption was 18 mW at 3 V voltage supply, and IIP3 was 3.43 dBm ensuring a high linearity in SiGe bipolar process.     

Probability method for cryptanalysis of general multivariate modular linear equation

Finding the solution to a general multivariate modular linear equation plays an important role in cryptanalysis field. Earlier results show that obtaining a relatively short solution is possible in polynomial time. However, one problem arises here that if the equation has a short solution in given bounded range, the results outputted by earlier algorithms are often not the ones we are interested in. In this paper, we present a probability method based on lattice basis reduction to solve the problem. For a g...     

MPEG4编码器二维DCT变换的FPGA实现及优化

本文提出了一种适用于MPEG4视频编码系统的二维DCT的FPGA设计方案，该方案具有实时、高精度、易于FPGA实现的特点。在设计中，分别对DCT的算法及实现方法进行了分析和选择；在此基础上，对系统的结构进行了优化，提出了一种不同于传统二维DCT系统的新结构。最后对IDCT单元的运算精度进行了验证。     

基于遗传算法的车用永磁式缓速器设计优化方法

永磁式缓速器是一种新型行车辅助制动装置.提出永磁式缓速器的多学科概念分析模型,分析电磁场参数、结构参数和温度参数等多学科对缓速器整体性能的影响;以缓速器的制动力矩最大为优化目标,设计变量包括永磁体周向宽度和轴向长度、永磁体个数、转子鼓内半径、转子鼓厚度、气隙.约束条件是许用温升、软磁材料饱和磁通量密度和结构几何关系.利用遗传算法对设计模型进行全局优化,获得初步的设计变量优化数值.文中的多学科设计优化方法是有效的,可用于工程设计.