检索结果-南通市图书馆

The regular representation and regular covariant representation of crossed products of Woronowicz C^(*)-algebras

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 2005年第9期48卷 1245-1259页

作者： ZHANG Xiaoxia~(1,2. & GUO Maozheng~(1,3) 1. School of Mathematical sciences,Peking university,{2. 100871,china 2. Department of Mathematics,Yantai university,Yantai 2.4005,china 3. LMAM,Peking university,{2. 100871,china 1. School of Mathematical sciences Peking University 100871 Beijing China 2. Department of Mathematics Yantai University 264005 Yantai China 3. LMAM Peking University 100871 Beijing China

In this paper,it is shown that the regular representation and regular covariant representation of the crossed products A×α G correspond to the twisted multiplicative unitary operators,where A is a Woronowicz C~*-algebra acted upon by a discrete group ***,it is also shown that the regular covariant C~*-algebra is the Woronowicz C~*-algebra which corresponds to a multiplicative ***,an explicit description of the multiplicative unitary operator for C(SU_q(2. )×α (?) is given in terms of those of the Woronowicz C~*-algebra C(SU_q(2. ) and the discrete group G.

关键词： multiplicative unitary operator, Woronowicz C*-algebra, crossed product.

The features of gravity field and deep structure in western part of the South Yellow Sea

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2000年第8期45卷 759-764页

作者： WANG Qianshen1 & AN Yulin1. Institute of Geophysics, Chinese Academy of sciences, beijing 100101,{2. 2. Chinese university of Geology, beijing 100083,{2. Institute of Geophysics Chinesc Academy of Sciences Beijing China Chinese university of Geology Beijing China

The gravity data from the sea region to the west of 12.° E of the South Yellow Sea have been processed and the feature of gravity fields analyzed. An experience relationship formula on the filter wavelength and corresponding depth has been put forward. Combined with the geological and seismic data, the deep tectonic framework and structural characters as well as possible favourable prospecting district for hydrocarbon in the South Yellow Sea have been discussed and analyzed.

关键词： western part of the South Yellow Sea gravity field deep structure.

外语高校助推中外人文交流的高质量特色发展路径

在线全文

学校读者我要写书评

暂无评论

北京教育（高教） 2024年第7期 12-14页

作者： beijing International Studies university 北京第二外国语学院

构建高质量高等教育体系需要高校错位竞争、特色办学和多样化发展。北京第二外国语学院始终秉承“中外人文交流”使命,坚定高水平特色大学办学类型,坚持以外语为主体、旅游为特色、多学科协同发展,在培育翻译后备力量、培养胜任中外人... 详细信息

构建高质量高等教育体系需要高校错位竞争、特色办学和多样化发展。北京第二外国语学院始终秉承“中外人文交流”使命,坚定高水平特色大学办学类型,坚持以外语为主体、旅游为特色、多学科协同发展,在培育翻译后备力量、培养胜任中外人文交流和国际传播的外语人才方面表现出显著优势,在推动国家文化和旅游高质量发展方面提供全方位智力支持,在服务北京国际交往中心功能建设方面作出突出贡献,探索形成了外语高校特色办学的高质量发展路径。

关键词：高水平特色型大学中外人文交流外语旅游

Photogeneration of the free radicals and singlet oxygen by chrysophanol from rheum

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2004年第5期47卷 381-387页

作者： RAO Jing1,2. XIE Jie1, ZHAO Jingquan1 & ZHU Teng2.1. Key Laboratory of Photochemistry, Center for Molecular Science, Institute of Chemistry, The Chinese Academy of sciences, beijing 100080,{2. 2. university of Science and technology beijing, beijing 10083,{2. 1. Key Laboratory of Photochemistry Center for Molecular Science Institute of Chemistry The Chinese Academy of Sciences 100080 Beijing China 2. university of Science and technology {2. 10083 Beijing China

In the current work, chryosphanol (MHAQ) was isolated and purified from rheum, and the photosensitization activities were studied. In nitrogen-saturated DMSO solution, irradia- tion of chryosphanol (MHAQ) with visible light (>430 nm) produced the semiquinone radical anions (MHAQ??), which was intensified significantly by an electron donor NADH, suggesting electron transfer between the excited and ground state photosensitizer molecules. In an air-saturated DMSO solution, superoxide radical anions (O2.), trapped by DMPO, were detected. ?? It was proved that O2.was not originated from the singlet oxygen (1O2. but dependent on DMPO, ?? chrysophanol, oxygen and the irradiation time. The singlet oxygen and OH could also be pro- ? duced by the photosensitization of the photosensitizer. These suggest that chrysophanol pos- sesses the photosensitization activity via Type I mechanism and Type II mechanism. To evaluate the photosensitization activities of MHAQ, emodin and mixed anthraquinone derivatives ex- tracted from rheum, the relative productivities of O2.were estimated to be 1.8, 1.1 and 1.0 re- ?? spectively and the quantum yields for singlet oxygen to be 0.36, 0.53 and 0.14 respectively. Therefore, these low-cost pigments may be potentially used as phototherapeutic medicine for some kind of vascular diseases or photo-activated pesticides.

关键词： chrysophanol, ESR, semiquinone radical anions, superoxide radical anions, hydroxyl radical, singlet oxygen.

Effect of As Interstitial Diffusionon on the Properties of Undoped Semi-insulating LECGaAs

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2001年第3期20卷 187-191页

作者： Ruixia Yang, Fuqiang Zhang, Nuofu Chen 1) Hebei university of technology, Tianjin 300130,{2. 2. Institute of Semiconductors, Chinese Academy of sciences, beijing 100083,{2. Hebei Univ Technol Tianjin 300130 Peoples R China Chinese Acad Sci Inst Semicond Beijing 100083 Peoples R China

Annealing was carried out at 950 and 112. degreesC under various As pressure for undoped (ND) semi-insulating (SI) LECGaAs. The effects of annealing on native defects and electrical properties were investigated. Experimental results indicate that, after an annealing at 950 degreesC for 14 h under low As pressure, the Hall mobility decreases and the resistivity increases dramatically for the samples. These changes in electrical properties are due to the generation of intrinsic acceptor defects, and the generation of the intrinsic acceptor defects originates from the outdiffusion of As interstitial at high temperature. The generation of the intrinsic defects and these changes in electrical properties can be suppressed by increasing the applied As pressure during annealing. The concentration of the main donor defect E12.(AsGaVGa) can be decreased by about one order of magnitude by an evacuated annealing at 112. degreesC for 2.8 h followed by a fast cooling. The decrease in E12.concentration can also be suppressed by increasing the As pressure during annealing.

关键词： semi-insulating GaAs intrinsic acceptor defects As interstitial indiffusion As pressure annealing

Nanostructured Sulfide Composite Coating Prepared by Atmospheric Plasma Spraying

在线全文

学校读者我要写书评

暂无评论

材料工程 2006年第Z1期34卷 281-284页

作者： GUAN Yao-hui~1,XU Yang~1,ZHENG Zhong-yu~2.TONG Xiao-hui~2.1 Engineering college of china Agricultural {2.,beijing 100083,china 2.beijing Research Institute of Mechanical & Electrical technology,beijing 100083,china) Engineering college China Agricultural University Beijing 100083 China beijing Research Institute of Mechanical and Electrical technology Beijing 100083 China

Nanostructured FeS-SiC coating was deposited by atmospheric plasma spraying（APS）.The microstructure and phase composition of the coating were characterized with SEM and XRD,*** addition,the size distribution of the reconstituted powders and the porosity of the coating have been *** was found that the reconstitiuted powers with sizes in the range of 2. to 80 μm had excellent flowability and were suitable for plasma spraying *** as-sprayed FeS-SiC composite coating exhibited a bimodal distribution with small grains（30～80nm） and large grains（100～2.0nm）.The coating was mainly composed of FeS and SiC,a small quantity of Fe1-xS and oxide were also *** porosity of the coating was approximately 19%.

关键词： plasma spraying nanostructured FeS-SiC composite coating

NON-EQUILIBRIUM SEGREGATION OF Si ON Al-0.35 wt-% Si ALLOY SURFACE

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1993年第8期6卷 98-101页

作者： CHEN Niug YU Zongsen university of Science and technology {2.,{2.,china professor,Department of Materials Physics,university of Science and technology {2.,{2. 100083,china beijing Univ of Science and Technology Beijing China

Si segregation was observed in the vacancy condensation pits,formed by supersaturated vacancies beneath the oxidation layer of Al-0.35wt-％Si alloy,by optical microscopy,X- ray photoelectron spectroscopy and microhard... 详细信息

关键词： non-equilibrium segregation vacancy AI-Si alloy surface Si

Recycling of Spent Nickel-Cadmium Batteries

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2000年第2期14卷 126-131页

作者： Xanghua Kong Pingnan Wu(Metallurgy School, university of Science and technology {2., {2. 100083, china) Metallurgy School University of Science and Technology Beijing Beijing 100083 China

A technique for recycling spent nickel-cadmium batteries, which makes separaion of cadmium and nickel possible, is developed by laboratory-scale experiments. NH3-H2.O3 aqueous solution was used in this leaching technique. Since neutralization and/or solvent extraction were not required in the separation procedure of nickel and cadmium, the closed systemizaion of the process becomespossible. Experimental results show that, (1) if the NH3 concentraion of leaching solution is sufficiently high and the ratio of H2.O3 toNH3 is properly adjusted, both Ni(OH)2.and Cd(OH)2.react with NH, and quickly dissolve into leaching solution, and (2. Ni(OH)2.can beconverted into insoluble NiO by calcination at 500℃, and CdO from Cd(OH)2.by calcination maintains good solubility in NH3-H2.O3aqueous solution. As a conclusion, the recycling technique characterized by two step leaching can be developed based on such changesin dissolution behavior by calcination. Meanwhile, the yields of 99.8% for nickel and 97.6% for cadmium are obtained, and the puritiesof Recycling of Spent Nickel-Cadmium BatterieRecycling of Spent Nickel-Cadmium Batteries Recycling of Spent Nickel-Cadmium Batteriesrecovered nickel and cadmium are 99.9% and 98.6%, respectively.

关键词： nickel-cadmium batteries recycling, ammonia leaching closed system environmental protection

Parameter identification theory of a complex model based on global optimization method

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2008年第11期51卷 1722-1732页

作者： QU Jie1, JIN QuanLin2.& XU BingYe3 1 college of Automotive Engineering, South china {2. of technology, Guangzhou 510640, china 2.beijing Research Institute of Mechanical and Electrical technology, beijing 100083, china 3 Department of Engineering Mechanics, Tsinghua {2., beijing 100084, china 1. college of Automotive Engineering South China University of Technology Guangzhou 510640 China 2. beijing Research Institute of Mechanical and Electrical technology Beijing 100083 China 3. Department of Engineering Mechanics Tsinghua University Beijing 100084 China

With the development of computer technology and numerical simulation technology, computer aided engineering (CAE) technology has been widely applied to many fields. One of the main obstacles, which hinder the further application of CAE technology, is how to successfully identify the parameters of the selected model. An elementary framework for parameter identification of a complex model is provided in this paper. The framework includes the construction of objective function, the design of the optimization method and the evaluation of the identified results, etc. The parameter identification process is described in this framework, taking the parameter identification of the superplastic constitutive model considering grain growth for Ti-6Al-4V at 92.°C as an example. The objective function is the weighted quadratic sums of the difference between the experimental and computational data for the stress-strain relationship and the grain growth relationship; the designed optimization method is a hybrid global optimization method, which is based on the feature of the objective function and incorporates the strengths of genetic algorithm (GA), the Levenberg-Marquardt algorithm and the augmented Gauss-Newton algorithm. The reliability evaluation of parameter identification result is made through the comparison between the calculated and experimental results and between the theoretical values of the parameters and the identified ones.

关键词： constitutive model parameter identification theory inverse analysis global optimization