检索结果-南通市图书馆

A rate based congestion control algorithm in networks with coexisting unicast and multicast sessions

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of university of science and technology Beijing 2003年第3期10卷 66-72页

作者： Qian Dong and Jianying XieSchool of Electronics & Information technology, shanghai jiaotong university, shanghai 200030, china Sch. of Electron. and Info. Technol. Shanghai Jiaotong Univ. Shanghai 200030 China

The optimal rate control problem in networks with unicast and multiratemulticast sessions is investigated. A penalty function approach is used to solve a convex programformulation of this problem, and then a heuristic rate control algorithm is derived. The algorithmis distributed, and suitable both for source-driven unicast sessions and receiver-driven multicastsessions. To obtain practical viability, the computational burden on core routers as well asend-hosts is kept very low, also is the overhead of network congestion feedback. Simulation resultsshow that the algorithm guarantees TCP (Transmission Control Protocol)-based unicast sessionscoexisting with multirate multicast sessions in a fair and friendly manner. It is also shown thatvarious fairness criteria of resource allocation could be achieved by choosing appropriate utilityfunctions, and resource-utilizing efficiencies would be likewise different.

关键词： multicast unicast congestion control rate control fairness

Identification and Characterization of hmr19 Gene Encoding a Multidrug Resistance Efflux Protein from Streptomyces hygroscopicus *** Strain 10-22

在线全文

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2004年第8期36卷 519-528页

作者： Lei QIN , Heng-An WANG1 , Zhong-Qin WU, Xiao-Feng ZHANG, Mei-Lei JIN,Zi-Xin DENG2, and Guo-Ping ZHAOshanghaiResearch Center of Biotechnology, shanghai Institute for Biological sciences, Chinese Academy of sciences,Graduate School of the Chinese Academy of sciences, shanghai 200233, china 1School of Agriculture and Biology, shanghai jiaotong university, shanghai 201101, china 2School of life science and Biotechnology, shanghai jiaotong university, shanghai 200030, china shanghaiResearch Center of Biotechnology Shanghai Institute for Biological Sciences Chinese Academy of Sciences Graduate School of the Chinese Academy of Sciences School of Agriculture and Biology Shanghai Jiaotong University

The hmr19 gene was cloned from Streptomyces hygroscopicus subsp. yingchengensis strain 10- 22, a bacterium strain producing agricultural antibiotics. Sequence similarity comparison indicates that hmr19 gene may encode a predicted protein with 14 putative transmembrane α-helical spanners, belonging to the drug:H+ antiporter-2 family of the major facilitator superfamily. The expression of hmr19 in the mycelium of strain 10-22 was detected by Western blotting analysis. Gene replacement technology was employed to construct an hmr19 disruption mutant. The growth inhibition test against different antibiotics indicated that the mutant strain was 5–20 fold more susceptible to tetracycline, vancomycin and mitomycin C than the parental wild type strain. The mutant took up tetracycline much faster and accumulated more antibiotics than the wild type strain 10-22. While with the addition of an energy uncoupler, carbonyl cyanide m- chlorophenylhydrazone, the characteristics of the accumulation of [3H]tetracycline in these two strains were almost the same. It was thus concluded that hmr19 encoded a multidrug resistance efflux protein.

关键词： multidrug resistance (MDR) gene replacement (knockout) Streptomyces Streptomyces hygroscopicus subsp. yingchengensis strain 10-22

Lie bialgebras of generalized Witt type

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china Mathematics 2006年第4期49卷 533-544页

作者： SONG Guang’ai & SU Yucai college of Mathematics and Information science, Shandong Institute of Business and technology, Yantai 264005, china Department of Mathematics, university of science and technology of china, Hefei 230026, china Department of Mathematics, shanghai jiaotong university, shanghai 200240, china college of Mathematics Information science Shandong Institute of Business technology Yantai 264005 China Department of Mathematics University of Science technology of china Hefei 230026 China Department of Mathematics Shanghai Jiaotong University Shanghai 200240 China

In this paper, all Lie bialgebra structures on the Lie algebras of generalized Witt type are considered. It is proved that, for any Lie algebra W of generalized Witt type, all Lie bialgebras on W are the coboundary triangular Lie bialgebras. As a by-product, it is also proved that the first cohomology group H1(W, W(?)W) is trivial.

关键词： Lie bialgebras, Yang-Baxter equation, Lie algebra of generalized Witt type.

A Resistivity Gradient Piezoelectric FGM Actuator

在线全文

学校读者我要写书评

暂无评论

Journal of Materials science & technology 2000年第4期16卷 383-386页

作者： S. U.Adikary and Zhongyan MENG (School of Materials science and Engineering, shanghai university, shanghai 201800, china) Dengren JIN (School of Materials science and Engineering, shanghai jiaotong university, shanghai 200030, china) School of Materials science and Engineering Shanghai University Shanghai 201800 China School of Materials science and Engineering Shanghai Jiaotong University Shanghai 200030 China

A resistivity gradient actuator based on lead zirconate titanate ceramics was successfully developed and the bending deflections up to 140 μm were obtained. The actuator material was a matrix of PZT ceramic into which smooth gradient of piezoelectric activity was introduced. The application of an electric field then causes the actuator to bend due to differential strains induced by the piezoelectric effect. The resistivity gradient of the actuator was achieved by doping PZT with suitable donor and acceptor dopants. PZT powder was modified and synthesized by using two stage powder fabrication method. The actuator was fabricated by uniaxial pressing followedby isostatic pressing with two layers of different resistivities.

关键词： PZT FGM

Improving TCP Performance over Wireless Links Using Link-Layer Retransmission and Explicit Loss Notification

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2002年第4期13卷 17-23页

作者： Zhou Zhizhao & Han Zhengzhi college of Electronic and Information Engineering, shanghai jiaotong university, shanghai 200030, P. R. china college of Electronic and Information Engineering Shanghai Jiaotong University Shanghai 200030 P. R. China

In order to support the mobility of computers during communication, the transport control protocol (TCP) connections between fixed host and mobile host often traverse wired and wireless networks, and the recovery of the losses due to wireless transmission error is much different from congestion control. This paper analyzes the interaction between TCP and link layer retransmission scheme when the correlated packet are losses handled, indicates that a higher value of the maximum number of successive link layer timeout retransmissions has an adverse effect on TCP ability to perform congestion control rapidly. To achieve a better TCP performance, the paper proposes a strategy combining link-layer selective-reject automatic repeat request (ARQ) with explicit loss notification mechanism, which can respond to congestion quickly while keeping wireless link more reliable, and make TCP react to the different packet losses more suitably.

关键词： Congestion control (communication) Mechanisms Performance Transmissions

Physical Simulation of Nonmetallic Particle Movement in Al Melt under Electromagnetic Field

在线全文

学校读者我要写书评

暂无评论

Journal of Materials science & technology 2001年第4期17卷 463-465页

作者： Tianxiao LI, Zhenming XU,Baode SUN,Da SHU and Yaohe ZHOU School of Materials science and Engineering, shanghai jiaotong university, shanghai 200030, china shanghai Jiao Tong Univ Sch Mat Sci & Engn Shanghai 200030 Peoples R China

Physical simulation is used to study the movement of nonmetallic particles in Al melt in electro- magnetic field. It is found that the terminal velocity of particles in different Reynolds number range has different functions. By confirming drag force coefficient of nonmetallic particles with Reynolds number in the range of 0.2-10 and 10-25 respectively, two functions of terminal ve- locity for spherical nonmetallic particles have been got accordingly, which provide a theoretical basis for separating nonmetallic inclusions from Al melt in electromagnetic field.

关键词： Al Physical Simulation of Nonmetallic Particle Movement in Al Melt under Electromagnetic Field Simulation

ON INTELLIGENTIZED TECHNOLOGIES FOR MODERN WELDING MANUFACTURING

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2003年第4期16卷 367-370页

作者： Chen ShanbenQiu TaoLin TaoWu YixiongInstitute of Welding Engineering,shanghai jiaotong university,shanghai 200030, china Institute of Welding Engineering Shanghai Jiaotong University 上海 200030

A short survey on researching and developing status of intelligenttechnologies in modem welding manufacturing is given. According to the developing trend of advancedmanufacturing technology, a concept on intelligentized welding manufacturing engineering (IWME), ispresented for systematization of researching and developing domains on welding automation,intelligentized welding, robotic and flexible welding and advanced welding manufacturingtechnologies. And key technologies of welding intelligent manufacturing and its developing trend inthe future are investigated.

关键词： Intelligentized technology Welding manufacturing engineering Intelligentcontrol Robotic welding Welding automation

Perspective in Development of Shape Memory Materials Associated with Martensitic Transformation

在线全文

学校读者我要写书评

暂无评论

Journal of Materials science & technology 1994年第2期10卷 107-110页

作者： Zuyao XU (T. Y.Hsu) (shanghai jiaotong university, shanghai, 200030, china) shanghai jiaotong Univ Shanghai China

By consideration of the characteristics of martensitic transformation and the derivation from the application of the group theory to martensitic transformation, it may be concluded that the shape memory effect (SME) can be attained in materials through a martensitic transformation and its reverse transformation. only when there forms single or nearly single variant of martensite, with an absence of the factors causing the generation of the resistance against SME. on this principle, various shape memory materials including nonferrous alloys. iron-based alloys and ceramics containjng zirconia are expected to be further developed. A criterion for thermoelastic martensitic transformation is presented, Factors which may act as the resistance against SME in various materials are briefly described

关键词： Ni Perspective in Development of Shape Memory Materials Associated with Martensitic Transformation

Organic Solvents Mediate Self-assembly of GAV-9 Peptide on Mica Surface

在线全文

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2007年第4期39卷 285-289页

作者： Hai LI~(1,3) Feng ZHANG~1 Yi ZHANG~1* Jianhua HE~1 Jun HU~(1,2) 1 shanghai Institute of Applied Physics,Chinese Academy of sciences,shanghai 201800,china 2 Bio-X life sciences Research Center.college of life science and Biotechnology,shanghai jiaotong university,shanghai 200030,china 3 Graduate School of the Chinese Academy of sciences,Beijing 100049,china shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800 China Graduate School of the Chinese Academy of sciencesBeijing 100049 China Bio-X life sciences Research Center College of Life Science and Biotechnology Shanghai Jiaotong UniversityShanghai 200030 China

Self-assembly of peptides into fibrils and other morphologies has attracted much attention inmany fields,especially in nanofabrication,pathology and *** this paper,self-assembly of GAV-9peptide in organic solvents,ethanol and acetone,was investigated using atomic force microscopy(AFM)and attenuated total reflectance-Fourier transform infrared spectroscopy(ATR-FTIR).The results indicatedthat GAV-9 self-assembled into various nanostructures in both solvents after deposited and evaporated *** with β-sheet conformation were observed in both solvents when the peptide concentrationwas higher than 280 μ***,ordered fibrils with β-sheet conformation were formed in ethanol,butnot in acetone,with a peptide concentration ranging from 7 μM to 28 μ*** attribute the formation ofvarious nanostructures to the different physicochemical properties of the polar organic solvents on the self-assembly of GAV-9 peptide.

关键词： self-assembly GAV-9 peptide organic solvents ATR-FTIR AFM