多元奇偶函数重积分的简捷求法     

胡小平  任全红  李元东 《绵阳师范学院学报》2009,28(2)

从给出区域的对称性定义、多元函数在对称区域上的奇偶性定义出发,引出、证明了关于多元奇偶函数重积分的两个基本性质.并利用典型例题阐述了两个定理及推论在计算多元奇偶函数重积分中的应用.  相似文献   

一种基于移动Agent的电子商务安全机制     

梁东莺  郑玮琨 《深圳信息职业技术学院学报》2009,7(4):32-35

安全问题制约着电子商务的的进一步发展,通过对移动Agent的环境下电子商务的分析,提出了在侈动设备中新型公钥密码系统——椭圆曲线密码系统。这种方法安全性好、简单、高效,能提高电子商务系统安全性,降低安全风险。  相似文献   

Self-certified multi-proxy signature schemes with message recovery   总被引：1，自引：0，他引：1  

Tzong-sun Wu  Chien-lung Hsu  Han-yu Lin 《浙江大学学报(A卷英文版)》2009,10(2):290-300

Multi-proxy signature schemes allow the original signer to delegate his/her signing power to n proxy signers such that all proxy signers must corporately generate a valid proxy signature on behalf of the original signer. We first propose a multi-proxy signature scheme based on discrete logarithms and then adapt it to the elliptic curve cryptosystem. With the integration of self-certified public-key systems and the message recovery signature schemes, our proposed schemes have the following advantages： （1） They do not require the signing message to be transmitted, since the verifier can recover it from the signature; （2） The authentication of the public keys, verification of the signature, and recovery of the message can be simultaneously carried out in a single logical step; （3） No certificate is needed for validating the public keys. Further, the elliptic curve variant with short key lengths especially suits the cryptographic applications with limited computing power and storage space, e.g., smart cards. As compared with the previous work that was implemented with the certificate-based public-key systems, the proposed schemes give better performance in terms of communication bandwidth and computation efforts.  相似文献   

Proportional integral plus multi-frequency resonant current controller for grid-connected voltage source converter under imbalanced and distorted supply voltage conditions   总被引：1，自引：0，他引：1  

Jia-bing Hu  Wei Zhang  Hong-sheng Wang  Yi-kang He  Lie Xu 《浙江大学学报(A卷英文版)》2009,10(10):1532-1540

This paper proposes a current control scheme for a grid-connected pulse width modulator （PWM） voltage source converter （GC-VSC） under imbalanced and distorted supply voltage conditions. The control scheme is implemented in the positive synchronously rotating reference frame and composed of a single proportional integral （PI） regulator and multi-frequency resonant controllers tuned at the frequencies of 2ω and 6ω, respectively. The experimental results, with the target of eliminating the active power oscillations and current harmonics on a prototype GC-VSC system, validate the feasibility of the proposed current control scheme during supply voltage imbalance and distortion.  相似文献   

Local curve fitting based Lagrange multiplier selection for Id-slice in multi-view video coding     

Shi-fang XU  Guo-bin CHEN  Hua-dong PAN  Ji-lin LIU 《浙江大学学报(A卷英文版)》2009,10(6)

The rate and distortion of Id-slice do not fit the globally linear relationship on a logarithmic scale. Lagrange multiplier selection methods based on the globally linear approximate relationship are neither efficient nor optimal for multi-view video coding (MVC). To improve the coding efficiency of MVC, a local curve fitting based Lagrange multiplier selection method is proposed in this paper, where Lagrange multipliers are selected according to the local slopes of the approximate curves. Experimental results showed that the proposed method improves the coding efficiency. Up to 2.5 dB gain was achieved at low bitrates.  相似文献   

线路坐标计算软件的设计与实现     

崔健彪  郭子珍  石晶 《长江工程职业技术学院学报》2005,22(3):41-44

首先介绍了一种线路坐标计算的通用数学模型,之后用Visual C 6.0设计、实现基于该模型的线路坐标计算软件.应用结果表明,该软件可以解算基本型、S型、卵型、凸型、复合型、C型等诸多复杂线形的任意指定点的坐标,解算结果准确可靠.  相似文献   

大跨度后张曲线预应力现浇框架梁的施工工艺     

吴锦霞  姜丽 《安阳工学院学报》2005,(6):33-35

安阳某多层厂房的框架梁采用了后张曲线预应力混凝土结构,本文介绍了波纹管曲线放样、钢绞线编束、波纹管就位固定、钢绞线束张拉等工序的施工工艺,同时对曲线预应力选材进行了对比分析.  相似文献   

我国优秀短距离速滑运动员弯道滑冰腿部肌电特征研究     

吴新炎  陈月亮 《北京体育大学学报》2014,37(10):77-82

摘要：目的：通过分析短距离速滑运动员弯道单步周期腿部肌电特征,探讨弯道单步周期腿部肌肉动作和协调模式,发现腿部力量训练可能存在的问题。方法：采集运动员第一弯道2-6连续5次单步周期肌电图,原始肌电图进行全波整流处理,再进行均化处理。结论：1）单步周期收腿阶段大小腿折叠可能是由蹬伸动作的后效应引起的随势动作,踝关节在右单步周期收腿阶段背屈,落腿阶段拓屈,左单步周期收腿阶段和落腿阶段前期背屈,落腿阶段后期拓屈;2）左单步周期重心转移阶段腓肠肌表现出与胫骨前肌共激活,蹬冰阶段胫骨前肌表现出与腓肠肌共激活,但激活程度逐渐降低,直至消失。蹬冰期股四头肌和股后肌群表现共激活协调模式,左单步周期协调性更高;3）在实践训练过程中对胫骨前肌、股直肌和臀大肌存在认识不足的问题。  相似文献   

公路曲线边坡设计探讨     

孙彦卓  王冬生 《黑龙江科技信息》2009,(17):246-246

阐述了公路曲线边坡的美学效应和安全特性,并对曲线边坡的设计做了重点介绍。  相似文献   

关于二元函数极限的注记     

陈素君 《中国科技信息》2009,(14):43-44

本文通过例题分析纠正了学习者在学习多元微积分时,对二元函数极限概念理解上易产生的一个偏差;给出并严格证明了一个相关的命题,以使学习者进一步正确掌握二元函数极限的概念.  相似文献