检索结果-南通市图书馆

Robust digital receiver for EPC sensor network

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2013年第1期24卷 44-51页

作者： cheng jin Sung Ho Cho Department of Electronics and Computer Engineering Hanyang University

A robust digital receiver based on a matched filter （MF） is proposed for the radio frequency identification （RFID） reader system to enhance the reliability of signal processing in the electronic product code （EPC） sensor network （ESN）. The performance of the proposed receiver is investigated by examining the anti-collision algorithm in the EPC global Class1 Generation2 protocol. The validity and usefulness are demonstrated by both computer simulations and experiments. Based on the verification results, comparing with the conventional zero crossing detector （ZCD） based receiver, the proposed receiver is very robust against strong amplitude distortions and considerable frequency deviations happening on the backscattered signal from a passive tag.

关键词： electronic product code (EPC) sensor network (ESN) signal distortion matched filter radio frequency identification (RFID) receiver.

Generalization of 3D Mandelbrot and Julia sets

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第1期8卷 134-141页

作者： cheng jin TAN Jian-rong State Key Laboratory of CAD ＆ CG Zhejiang University Hangzhou 310027 China

In order to further enrich the form of 3D Mandelbrot and Julia sets, this paper first presents two methods of generating 3D fractal sets by utilizing discrete modifications of the standard quaternion algebra and analyzes the limitations in them. To overcome these limitations, a novel method for generating 3D fractal sets based on a 3D number system named ternary algebra is proposed. Both theoretical analyses and experimental results demonstrate that the ternary-algebra-based method is superior to any one of the quad-algebra-based methods, including the first two methods presented in this paper, because it is more intuitive, less time consuming and can completely control the geometric structure of the resulting sets. A ray-casting algorithm based on period checking is developed with the goal of obtaining high-quality fractal images and is used to render all the fractal sets generated in our experiments. It is hoped that the investigations conducted in this paper would result in new perspectives for the generalization of 3D Mandelbrot and Julia sets and for the generation of other deterministic 3D fractals as well.

关键词： Mandelbrot set Julia set Fractal Ray-casting Quad algebra Ternary algebra

An optimization of the shape of FAST reflector panels

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2010年第8期10卷 797-804页

作者： Heng-Qian Gan cheng-jin jin National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

The Five-hundred-meter Aperture Spherical radio Telescope （FAST） will be the largest radio telescope in the world. The surface tolerance of the main reflector is one of the most important parameters for evaluating the performance of the telescope. The relationship between the reflector＇s surface tolerance and the curvature of FAST reflector panels is analyzed and discussed. According to the calculation of reflector tolerance and antenna gain, an optimized panel shape for minimum surface tolerance and maximum gain is derived. The far field pattern of the FAST telescope is presented while the optimized shape is utilized for reflector panels. The results show that FAST could be operated at a frequency band of 8 GHz or even higher with an acceptable efficiency.

关键词： telescopes -- reflector panel -- antenna tolerance

在线全文

学校读者我要写书评

暂无评论

从标准的制修订看ADI生产技术的进步

铸造 2024年第1期73卷 53-59页

作者：闫启栋王静李强刘金城禹州市恒利来新材料股份有限公司河南许昌452570 康迈(潍坊)机械有限公司山东潍坊261308 中国铸造协会北京100000

等温淬火球墨铸铁(ADI)由于具有高强度、高韧性、抗疲劳及耐磨、抗磨等综合性能,为21世纪人们关注的热点和最具发展潜力的材料之一。国外ADI的生产技术及应用发展较快,相关标准制定和更新比较及时而且不断完善。随着国内ADI生产技术水... 详细信息

等温淬火球墨铸铁(ADI)由于具有高强度、高韧性、抗疲劳及耐磨、抗磨等综合性能,为21世纪人们关注的热点和最具发展潜力的材料之一。国外ADI的生产技术及应用发展较快,相关标准制定和更新比较及时而且不断完善。随着国内ADI生产技术水平的提高,我国ADI等温淬火球墨铸铁件的标准从早期的企业标准到国家标准、团体标准,形成了不同层级的标准体系。2009年我国发布了GB/T 24733—2009《等温淬火球墨铸铁件》,2021年发布了团体标准T/CFA 020101243—2021《等温淬火球墨铸铁件》;2022年又对GB/T 24733《等温淬火球墨铸铁件》进行了修订。从不同层级的标准制修订技术指标的提高可以看出我国ADI生产技术近十年来取得的进步。

关键词：等温淬火球墨铸铁材料标准

挂篮悬浇连续梁桥上跨既有高铁隧道施工及监测关键技术

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

建筑机械 2024年第4期 94-101页

作者：刘海程金平中交二航局第四工程有限公司安徽芜湖241000

文章以龙围大桥为工程背景,研究了连续梁桥上跨既有高铁隧道的施工及监测关键技术。龙围大桥0#块采用型钢支架施工,主桥节段块采用菱形挂篮悬浇施工。首先设计了由主桁、行走锚固、模板等多个系统组成的连体式菱形挂篮,各主要结构间通... 详细信息

文章以龙围大桥为工程背景,研究了连续梁桥上跨既有高铁隧道的施工及监测关键技术。龙围大桥0#块采用型钢支架施工,主桥节段块采用菱形挂篮悬浇施工。首先设计了由主桁、行走锚固、模板等多个系统组成的连体式菱形挂篮,各主要结构间通过高强螺栓、焊接等方式连接为整体,连接强度高。研究并详细介绍了支架搭设及拆除、挂篮安装及预压、挂篮行走等施工关键技术,监测结果表明施工过程中既有隧道围岩压力较小,本项目施工方法有效保障了隧道安全。最后基于数值模拟方法研究了挂篮主要构件的强度及刚度。结果表明,混凝土最重、最长梁段浇筑及挂篮行走时各主要构件的强度及刚度均满足设计与规范要求。本项目成果有效减少了施工区大型设备的使用,降低了施工风险,保障了工程质量。

关键词：连续梁桥挂篮悬浇上跨隧道支架现浇施工技术

An efficient method for identification of risk factors

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第12期52卷 3626-3631页

作者： cheng jin XIAO Rucheng Department of Bridge Engineering Tongji UniversityShanghai 200092China

This paper presents a method to identify risk factors during bridge *** method integrates the concepts of analytical hierarchy process and fuzzy consistent matrix *** advantage of the method is that instead of using 9-point scale of relative importance of the conventional analytical hierarchy process,it uses a 3-point scale to describe the scale of importance,thus greatly simplifying the identification problem of risk ***,the difficulties of making judgment and comparison caused by uncertainty that jeopardizes the accuracy of the results in the conventional analytical hierarchy process can also be *** advantage of the method is that it does not involve consistency checking,thus saving a large amount of CPU *** has been demonstrated with a numerical example that the proposed fuzzy analytical hierarchy process based on 3-point scale can offer significant computational savings over the conventional analytical hierarchy process.

关键词： analytical hierarchy process risk fuzzy consistent matrix identification

经三角肌与三角肌胸大肌入路治疗NeerⅡ、Ⅲ型老年肱骨近端骨折的效果比较

在线全文

学校读者我要写书评

暂无评论

中国医学创新 2024年第1期21卷 1-4页

作者：杨景瑞程进景德镇市第一人民医院创伤中心骨科江西景德镇333000

目的:探讨经三角肌与三角肌胸大肌入路治疗NeerⅡ、Ⅲ型老年肱骨近端骨折的效果。方法:选取2021年1月—2022年12月景德镇市第一人民医院收治的48例NeerⅡ、Ⅲ型老年肱骨近端骨折患者,按照不同的手术方式分为观察组(经三角肌入路)和对照... 详细信息

目的:探讨经三角肌与三角肌胸大肌入路治疗NeerⅡ、Ⅲ型老年肱骨近端骨折的效果。方法:选取2021年1月—2022年12月景德镇市第一人民医院收治的48例NeerⅡ、Ⅲ型老年肱骨近端骨折患者,按照不同的手术方式分为观察组(经三角肌入路)和对照组(经三角肌胸大肌入路),各24例。对比两组手术情况、肩关节功能、凝血指标和疼痛程度。结果:观察组术中出血量少于对照组,骨折愈合时间和手术时间均短于对照组,差异均有统计学意义(P<0.05)。观察组术后1、6个月Neer肩功能评分均高于对照组,差异均有统计学意义(P<0.05)。观察组术后3 d凝血酶原时间(PT)及活化部分凝血活酶时间(APTT)均低于对照组,观察组FIB较术前降低,对照组FIB较术前升高,观察组低于对照组,差异均有统计学意义(P<0.05)。观察组术后3 d疼痛数字评价量表(NRS)评分低于对照组,差异有统计学意义(P<0.05)。结论:NeerⅡ、Ⅲ型老年肱骨近端骨折患者选择经三角肌入路方式进行手术,能够缩短手术时间和骨折愈合时间,减少术中出血量,有利于肩关节功能恢复,改善凝血指标及疼痛程度。

关键词：经三角肌胸大肌入路疼痛程度经三角肌入路肩关节功能老年肱骨近端骨折

ON SPECTRAL METHODS FOR VOLTERRA INTEGRAL EQUATIONS AND THE CONVERGENCE ANALYSIS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2008年第6期26卷 825-837页

作者： Tao Tang Xiang XU jin cheng Department of Mathematics Hong Kong Baptist University Kowloon Tong Hong Kong China School of Mathematics Fudan University Shanghai 200433 China

The main purpose of this work is to provide a novel numerical approach for the Volterra integral equations based on a spectral approach. A Legendre-collocation method is proposed to solve the Volterra integral equations of the second kind. We provide a rigorous error analysis for the proposed method, which indicates that the numerical errors decay exponentially provided that the kernel function and the source function are sufficiently smooth. Numerical results confirm the theoretical prediction of the exponential rate of convergence. The result in this work seems to be the first successful spectral approach （with theoretical justification） for the Volterra type equations.

关键词： Legendre-spectral method Second kind Volterra integral equations Convergence analysis.

MULTIPLICITY-PRESERVING TRIANGULAR SET DECOMPOSITION OF TWO POLYNOMIALS

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2014年第6期27卷 1320-1344页

作者： cheng jin-San GAO Xiao-Shan Key Laboratory of Mathematics Mechanization Institute of Systems ScienceAcademy of Mathematics and Systems ScienceChinese Academy of Sciences

In this paper, a multiplicity-preserving triangular set decomposition algorithm is proposed for a system of two polynomials, which involves only computing the primitive polynomial remainder sequence of two polynomials once and certain GCD computations. The algorithm decomposes the unmixed variety defined by two polynomials into square free and disjoint （for non-vertical components, see Definition 4） algebraic cycles represented by triangular sets which may have negative multiplicities. Thus, the authors can count the multiplicities of the non-vertical components. In the bivariate case, the amthors give a complete algorithm to decompose tile system into zeros represented by triangular sets with multiplicities. The authors also analyze the complexity of the algorithm in the bivariate ease. The authors implement the algorithm and show the effectiveness of the method with extensive experiments.

关键词： Algebraic cycle multiplicity-preserving primitive polynomial remainder sequence trian-gular set decomposition.