OALib Journal期刊

ISSN: 2333-9721




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匹配条件: “<br>张琨” ,找到相关结果约421314条。
Multiscale Methods For Nonlinear Analysis Of Composite Materials

Zhang Hongwu Wang Kunpeng,<br>洪武,
力学学报 , 2004,
Abstract: A composite material is called spatially periodic if it is possible to be decomposed into elementary components or cells of periodicity. The characteristic size of the single cell of periodicity is assumed much smaller than the geometrical dimensions of the structure which is therefore composed of a large number of cells. The great achievements have been obtained from the research of homogenization algorithm based on the elastic assumption. Because the failure process of material is generally related to the nonlinear analysis of the materials, the research work on the multi-scale analysis of the nonlinear behaviors of the materials is more significant for engineering applications. However, due to the difficulties of the solving of nonlinear problems, the research work will be more complex and more difficult than those performed for the elastic homogenization analysis. The numerical approach in the paper differs somewhat from those proposed in previous studies. For micro-macro analysis of periodic material composed of elastic granules with contact characteristics, this paper adopts the method which was developed by the first author. The basic principle of the method is based on the numerical constitutive model. The important features of developed algorithm are that during the process of establishing macroscopic constitutive law the stick-disengage-slip behaviors in the granular contact interfaces are taken into account. Different from the pure contact problem, the stick relationship considers initial stick cohesion between the granules when the sticking state is destroyed (the material will thus proceed a damaged state). For the micro-macroscopic analysis of multi-phase elastic-plastic materials, according to transformation field theory, a consistent algorithm for elastic-plastic material analysis on micro-macroscopic is proposed. The basic theories for the establishing of the numerical method are introduced first in the paper, and then the numerical technique is described in detail. Finally, the numerical example is presented to demonstrate the validity and efficiency of the two algorithms.

河南农业科学 , 2014,
Abstract: 为了开发中草药添加剂,试验选取600羽45周龄左右的罗曼褐壳蛋鸡,随机分为5组,每组重复3次,每次重复40只,分别在各处理组的基础日粮中添加0(CK)、1%(A)、5%(B)、10%(C)、15%(D)中草药,测定不同添加量中草药对蛋鸡生产性能及蛋品质的影响。结果显示:与CK相比,各试验组的破蛋率、畸形率均显著下降,其中C组最低,分别显著下降0.66、0.31个百分点,各试验组间差异均不显著;各试验组料蛋比均极显著下降,C组最低,降低了17.83%;各试验组产蛋率均极显著升高,C组最高,提高了10.93个百分点;各试验组蛋形指数、蛋壳厚度、蛋壳强度均有所增加,但差异均不显著;C组蛋黄颜色等级、蛋黄系数、哈氏单位、蛋黄比率均显著提高。表明,基础日粮中添加中草药能提高蛋鸡的生产性能、鸡蛋品质,其中以10%的添加量最佳。

武汉理工大学学报 , 2008,
Abstract: ?为满足当前对数字视频存储子系统的需求,通过分析全局文件系统(gfs)的体系结构和特性,提出了构建一个基于gfs文件系统的san的策略和实施,并将其作为视频服务器的存储子系统进行了性能测试。测试表明,该存储子系统提高了存储资源的共享性和总体性能,可以满足视频服务器大容量、高性能的存储要求。
Low Computational Load Anonymous Routing Protocol for Ad-hoc Networks

LIU Fang-bin,ZHANG Kun,ZHANG Hong,<br>刘方斌,,
计算机科学 , 2011,
Abstract: Nodes in Ad-hoc networks are limited in energy,have poor computational ability and move fast,and public key encryptions have heavy computational load,consume a lot of energy and have long computational cycle time,so public key encryptions are adapted for the Ad-hoc networks.The proposed anonymous routing protocols have a lot of public key encryptions.To reduces public key encryptions,we applied bilinear pairing and Zero Knowledge Proofs into anonymous routing protocol,and proposed a new anonymous routing pr...
Rapid Separation of Antiserum by Surface Modified Fe3O4 Nano-particles

Zhanwei Mao,Hui Wang,Juankun Zhang,<br>毛占伟,王 慧,
生物工程学报 , 2008,
Abstract: 采用硅烷化试剂Si(OC2H5)3C3H6NH2(APTES)对纳米Fe3O4颗粒表面进行氨基化改性后, 考察了不同浓度偶联剂戊二醛对于颗粒表面固定牛血清白蛋白(BSA)量的影响。此超顺磁性免疫铁颗粒(SPIO)加入兔抗BSA血清中特异性结合BSA抗体后, 用Gly-HCl缓冲液洗脱得到IgG。结果表明当戊二醛浓度大于10%时, 单位颗粒固定蛋白的量达到最大值约140 mg/mg, 10 min, 15 mg的SPIO即可将1 mL抗血清完全分离, 经过两次快速洗脱, 颗粒表面吸附的抗体即可得到纯化; 琼脂扩散实验表明分离后的抗体仍保持较高活性, SDS-PAGE电泳结果表明用此方法纯化后的兔抗BSA IgG纯度大于99%, 比传统的(NH4)2SO4法有了较大提高, 但纯化量并没有减少; SPIO在经过五次重复利用后仍能保持78%以上的分离效果。

光子学报 , 2002,
Abstract: Diamond films for field emission are prepared heterogeneously on (100)-oriented Si substrates in hot filament chemical vapor deposition(HFCVD) process,raw materials are a gas mixture of methane and hydrogen,and substrate temperature is lower than 800℃.Characterizations of the films grown in this way are measured by means of scanning electron microscopy (SEM),X-ray diffraction (XRD),transmission electron microscopy (TEM) and Raman spectroscopy.The results show that the films are polycrystalline and grown preferably in (111) crystal orientation.The shapes of (111) grains are seen to possess tips in SEM micrograph,so the films are fit for field emission.
Research on Laser Detection of Underwater Acoustic Signals

Qin HuiPing,Zhou TianHua,Zhang DeKun,<br>秦慧平,周田华,
红外 , 2005,
Abstract: The laser detection of underwater acoustic signals exploited a laser receiving technique. It uses light wave in air and uses acoustic wave under water. Because two best channels are combined together, it is an ideal method for remotely detecting underwater acoustic signals. The underwater acoustic signal can cause surface wave motion at waterair interface and modulate the magnitude of the laser beam falling on tile water surface. The modulated underwater laser signal can be detected by using a direct light intensity detecting method. In this paper, the feasibility of the laser detection of underwater acoustic signals is verified experimentally on the basis of theoretical analysis and some problems to be solved are discussed.
A Multi-Constrained QoS Multicast Routing Algorithm Based on Simulated Annealing

ZHANG Kun,WANG Heng,LIU Feng-Yu,<br>,王珩,刘凤玉
计算机科学 , 2005,
Abstract: This paper studies bandwidth-delay and delay variation constrained least-cost QoS multicast routing prob- lem, and proposes a QoS multicast routing algorithm (SABDMA) based on simulated annealing to solve this prob- lem. The algorithm selects proper parameters about simulated annealing, and finds least-cost multicast tree satisfying QoS constraints. In addition, to avoid enlargement of search area and increase of computing time, we put forward a "paths-switching" strategy. It constructs neighbor set in the range of feasible solutions according to the relationship between delay and delay variation. A large number of simulations demonstrates that the algorithm has characteristics of feasibility, stability and rapid convergence, and it can effectively construct multicast tree with lower cost according to QoS request, and has better real-time property.
Adaptive Threshold Background Modeling Algorithm Based on Chebyshev Inequality

ZHANG Kun,WANG Cui-rong,WAN Cong,<br>,王翠荣,万聪
计算机科学 , 2013,
Abstract: 背景建模是实现运动目标检测与跟踪的关键技术之一。在实时视频监控系统中,对背景建模算法的运行时间及所提取出的背景图像的实时性有很高的要求,针对这一问题,提出了一种基于切比雪夫不等式的自适应阈值背景建模算法。算法利用切比雪夫不等式计算像素点色度变化的概率估计值,提出了一种自适应阈值分类方法,它将像素点快速分类为前景点、背景点及可疑点,再利用核密度估计方法对可疑点进行进一步分类,最后利用背景更新算法提取实时背景图像。实验结果证明,该算法能快速有效地区分特征明显的背景点与前景点,提高了背景图像提取的速度,对可疑点利用核密度估计方法降低了背景分割的误差,背景建模效果理想,运算速度快,适用于实时视频监控系统。
Novel algorithm based on companding transformation to reduce PAPR in OFDM systems

ZHANG Guo-long,SHU Qin,CHENG Kun,<br>国龙,舒勤,
计算机应用研究 , 2011,
Abstract: 为了降低OFDM信号峰均功率比本文提出了一种新的压扩算法。新算法通过保持中值信号不变,压缩大信号,放大小信号,从而降低了OFDM信号峰均比。通过与现有压缩算法对比,分析了本文算法对PAPR性能和系统误码率的影响。实验仿真结果说明,本文算法可以获得更低的峰均比,降低计算复杂度。

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