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Local canonical correlation coefficients and canonical variables of groups of random variables

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chinese Science Bulletin 1998年第10期43卷 815-817页

作者： XU Xingzhong institute of Systems Science, chinese academy of sciences, beijing 100080, china institute of Systems Science Chinese Academy of Sciences Beijing China

The concepts of local correlation coefficient, local canonical correlation coefficients and local canonical variables of groups of random variables are defined, which generalize the classical concepts in two groups of random *** concepts together with total corresponding concepts clarify the correlativity among groups of random variables.

关键词： groups of random variables covariance matrix local canonical correlation coefficients local canonical variables.

SOLID PHASE TRANSITION OF SYNDIOTACTIC POLYSTYRENE IN SUPERCRITICAL CO_2

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chinese Journal of Polymer Science 2002年第3期20卷 191-196页

作者： Yu-ying Li Jia-song He State Key Laboratory of Engineering Plastics, Center for Molecular Science, institute of chemistry chinese academy of sciences, beijing 100080 china chinese Acad Sci Inst Chem Ctr Mol Sci State Key Lab Engn Plast Beijing 100080 Peoples R China

Solid phase transition of the a form crystals to the 3 form crystals in syndiotactic polystyrene (sPS) samples has occurred in supercritical CO2. This transformation is different from those detected under other conditions. The effects of some factors (e.g. time, temperature, and pressure) on the solid phase transformation of sPS in supercritical CO2 were analyzed in detail. Experimental results show that longer time, higher temperature or higher pressure favors the transformation of the a form crystals to the beta form crystals.

关键词： solid phase transition syndiotactic polystyrene supercritical CO2

Study on the atmospheric photochemical reaction of CF_3 radicals using ultraviolet photoelectron and photoionization mass spectrometer

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Science china chemistry 2008年第4期51卷 316-321页

作者： YAO Li1,2, DU Lin1,2, YIN shi1,2 & GE MaoFa1 1 beijing National Laboratory for Molecular sciences (BNLMS), State Key Laboratory for Structural chemistry of Unstable and Stable Species, institute of chemistry, chinese academy of sciences, beijing 100080, china 2 Graduate University of chinese academy of sciences, beijing 100080, china 1. beijing National Laboratory for Molecular sciences (BNLMS) State Key Laboratory for Structural Chemistry of Unstable and Stable Species Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China 2. Graduate University of chinese academy of sciences Beijing 100080 China

A study of the atmospheric photochemical reaction of CF3 radical with CO and O2 was performed by using a homemade ultraviolet photoelectron spectrometer-photoionization mass spectrometer (PES- PIMS). The electronic structures and mechanism of ionization and dissociation of CF3OC(O)OOC(O)- OCF3 were investigated. It was indicated that the two bands on the photoelectron spectrum of CF3OC(O)OOC(O)OCF3 are the result of ionization of an electron from a lone pair of oxygen and a fluo- rine lone pair of CF3 group. The outermost electrons reside in the oxygen lone pair. The experimental and theoretical first vertical ionization energy is 13.21 and 13.178 eV, respectively, with the PES and OVGF method. They are in good agreement. The photo ionization and dissociation processes were discussed with the help of theoretical calculations and PES-PIMS experiment. After ionization, the parent ions prefer the dissociation of the C-O bond and giving the fragments CF3OCO+ and CF3+. It demonstrated that the ultraviolet photoelectron and photoionization mass spectrometer could be ap- plied widely in the study of atmospheric photochemical reaction.

关键词： photochemical reaction CF3 radical ultraviolet photoelectron and photoionization mass spectroscopy transient species

MODIFICATION OF EPOXY RESIN WITH POLYSILOXANE BEARING PENDANT QUATERNARY AMMONIUM GROUPS

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chinese Journal of Polymer Science 2002年第6期20卷 537-541页

作者： Zuo-xin Huang Ying Huang Yun-zhao Yu The State Key Laboratory of Engineering Plastics, institute of chemistry chinese academy of sciences, beijing 100080 china chinese Acad Sci Inst Chem State Key Lab Engn Plast Beijing 100080 Peoples R China

Polysiloxane bearing pendant quaternary ammonium groups (PSI) was used to modify the surface properties of epoxy resins. In the cured resin, PSI formed the dispersed phase. Remarkable enrichment and gradient distribution of polysiloxane on the surface region of the epoxy resins were demonstrated by XPS analysis. The composition and properties of the surface of PSI-modified epoxy resin, which is in contact with the mold, are dependent on the material of the mold. Through the incorporation. of PSI, epoxy resins with low surface energy and low friction coefficient were obtained. Polysiloxane with lower ionic group content shows a higher degree of enrichment on the resin surface and leads to a higher contact angle against water, while the polysiloxane having optimum compatibility with the epoxy resin shows a greater effect in reducing the static friction coefficient of the resin against glass.

关键词： polysiloxane epoxy resin surface composition friction coefficient

RHEOLOGICAL MODIFICATION OF EPOXY RESINS WITH NANO SILICA PREPARED BY THE SOL-GEL PROCESS

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chinese Journal of Polymer Science 1999年第3期17卷 253-257页

作者： Xia Wang Jiang Li Cheng-fen Long Yun-zhao Yu PCLCC institute of chemistry, chinese academy of sciences, beijing 100080, china PCLCC is the Polymer chemistry Laboratory, chinese academy of sciences and china Petro-Chemica Corporation chinese Acad Sci Inst Chem PCLCC Beijing 100080 Peoples R China

Nano silica-modified epoxy resins were synthesized by the sol-gel process, The materials have the morphological structure of nano particales dispersed in the epoxy matrix. The dispersed phase formed a physical network in the resin and thus influenced the rheological behavior greatly. However, the nano silica did not show a significant influence on the mechanical properties of the cured resins.

关键词： epoxy resin nano silica mechanical properties rheology sol-gel process

Microstructure of Pd_(77.5)Au_6Si_(16.5) Alloy Droplet Solidified in a Drop Tube Process

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Journal of Materials Science & Technology 1996年第5期12卷 385-388页

作者： Liling SUN Qi WU Liwei SUN and Wenkui WANG (institute of Physics, chinese academy of sciences, beijing 100080, china) institute of Physics Chinese Academy of Sciences Beijing 100080 China

The microstructure development of Pd77.5Au6Si16.5 alloy droplet solidified in a drop tube process was studied. It was found that two distinct microstructures, i.e. (Pd,Au)3Si primary phase and Pd+(Pd,Au)3Si eutectic can be obtained when the droplet diameter is within the range between 2.3~0.4 mm. The morpologies of the (Pd,Au)3Si developed from dendrite trunk-like with single branching only into dendrite cluster-like with ternary branching with the decrease of the droplet diameter. When the droplet diameter is about 0.25 mm, the primary phase (Pd,Au)3Si almost disappears and the microstructure mainly shows Pd+(Pd,Au)3Si eutectic. The morphology of the eutectic transforms from fiber-like to plate-like with the decrease of the droplet diameter in the range between 2.3-0.25 mm. When the droplet diameter is about 0.19 mm, the microstructure is only the single phase of Pd solid solution

关键词： Microstructure of Pd Au6Si Alloy Droplet Solidified in a Drop Tube Process

Preparation and Characterization of Ultrafine ZrO_2 Powders from Solvent Extraction of Zr(Ⅳ) with Tri-n-butyl Phosphate in Kerosene from Nitric Acid Solutions

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Journal of Materials Science & Technology 1996年第6期12卷 439-444页

作者： Chuanfang YANG and Jiayong CHEN (institute of Chemical Metallurgy, chinese academy of sciences, beijing 100080, china)(To whom correspondence should be addressed) institute of Chemical Metallurgy Chinese Academy of Sciences Beijing 100080 China

Zr(IV) was extracted by tri-n-butyl phosphate in kerosene from concentrated nitric acid solutions and the formation of the third phase during extraction was experimentally investigated. Zirconia powders were prepared by using the loaded organic phase as the bulk solution precipitated with aqueous ammonia or NaOH solution. The powder prepared was characterized with TEM, XRD,EDAX and TG-DTA. Effects of some conditions on powder preparation were studied and it was shown that nanosized particles could be obtained from this extraction system but conditions should be carefully controlled for powder purity and particle size.

关键词： Zirconia

ON SELF-ABSORPTION CORRECTION IN EXCIMER FLUORESCENCE MEASUREMENTS OF POLYMER SOLUTIONS

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chinese Journal of Polymer Science 2000年第5期18卷 465-468页

作者： Xi-gao Jin Zhong Jiang Ming Ni Feng-lian Bai Ren-yuan Qian institute of chemistry, chinese academy of sciences, beijing 100080, china chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

The effect of self absorption on the ratio of excimer to monochromophore emission intensities, I-e/I-m, has been explored by experimentally changing the solution layer thickness of the emission light path traversed in the solution in the right-angle geometry. The result shows that data obtained by front-face geometry are better than those obtained by right-angle geometry even after correction to zero solution thickness. The correction formula based on geometric optics given by Tsai and Torkelson is not adequate.

关键词： excimer fluorescence self absorption polystyrene solution

THE PRIMAL-DUAL POTENTIAL REDUCTION ALGORITHM FOR POSITIVE SEMI-DEFINITE PROGRAMMING

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Journal of Computational Mathematics 2003年第3期21卷 339-346页

作者： Si-ming Huang(institute of Policy and Management, academy of Mathematics and System sciences, chinese academy of sciences, beijing 100080, china) institute of Policy and Management Academy of Mathematics and System Sciences Chinese Academy of Sciences 北京 100080

In this paper we introduce a primal-dual potential reduction algorithm for positive semi-definite programming. Using the symetric preserving scalings for both primal and dual interior matrices, we can construct an algorithm which is very similar to the primal-dual potential reduction algorithm of Huang and Kortanek [6] for linear programming. The complexity of the algorithm is either O(nlog(X0 · S0/ε) or O(nlog(X0· S0/ε) depends on the value of ρ in the primal-dual potential function, where X0 and S0 is the initial interior matrices of the positive semi-definite programming.

关键词： Positive semi-definite programming Potential reduction algorithms Complexity.