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finite Presentation of Alternating Groups

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Acta Mathematica Sinica,English Series 1995年第2期11卷 221-224页

作者： q. Mushtaq.f. Shaheen Department of Mathematics q.aid-i-Azam University Islamabad Pakistan

Graham Higman posed the q.estion: How small can the integers p and q.be made, while maintaining the property that all but finitly many alternating and symmetric groups are factor groups of △(2, p, q.=(x,y: x^2=y^P=(xy)~q.1)? He proved that for a sufficiently large n, the alternating group is a homomorphic image of the triangle group △(2,p, q. where p=3 and q.7. Later, his result was generalized by proving the result for p=3 and q.7. Choosing p=4 and q.17 in this paper we have answered the "Hiq.an q.estion".

关键词： finite Presentation of Alternating Groups

EXPERIMENTAL RESEARCH AND NUMERICAL SIMULATION Of LASER SHOCK fORMIng Of TA2 TITANIUM SHEET

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 347-354页

作者： f. Wang Z. q. Yao J. Hu q.L. Deng School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200030 China

Laser shock forming （ISf） was a new techniq.e realized by applying an impulsive pressure generated by laser-induced shock wave on the surface of metal sheet. LSf of metal sheet was investigated with experiments and numerical simulation. The basic theories were introduced; the surface q.ality and deformation of the processed titanium sample （TA2） were examined; ABAq.S was used to simulate ISf and the central displacement of the shocked region was measured and compared with the simulation. Overlapped ISf treatment was experimentally carried out to produce groove and simulation. The results showed that the surface q.ality and the microstructure with single laser pulse had no remarkable change, and ablation was observed on the surface of the sample with overlapped pulses. The deformation observed in the numerical simulation agreeed with that observed in the experimental measurement q.ite well.

关键词： laser shock forming numerical simulation surface q.ality deformation

Maximum Path Information and fokker-Planck Eq.ation

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Chinese Physics Letters 2008年第4期25卷 1165-1167页

作者：李炜 q. A. Wang A. Le Mehaute Complexity Science Center and Institute of Particle Physics Huazhong Normal University Wuhan 430079 Institut Superieur des Mateiaux du Mans 44 Avenue F.A. Bartholdi 72000 Le Mans France

We present a rigorous method to derive the nonlinear fokker-Planck （fP） eq.ation of anomalous diffusion directly from a generalization of the principle of least action of Maupertuis proposed by Wang [Chaos, Solitons ＆ fractals 23 （2005） 1253] for smooth or q.asi-smooth irregular dynamics evolving in Markovian process. The fP eq.ation obtained may take two different but eq.ivalent forms. It was also found that the diffusion constant may depend on both q.（the index of Tsallis entropy [J. Stat. Phys. 52 （1988） 479] and the time t.

关键词： MATHEMATICAL-THEORY COMMUNICATION DYNAMICS

Nonlinear mechanics of a ring structure subjected to multi-pairs of evenly distributed eq.al radial forces

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Acta Mechanica Sinica 2017年第5期33卷 942-953页

作者： q. Chen f. Sun Z. Y. Li L. Taxis N. Pugno Biomechanics Laboratory School of Biological Science and Medical Engineering Southeast University State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics School of Chemistry Physics and Mechanical EngineeringQueensland University of Technology (QUT) Laboratory of Bio-Inspired and Graphene Nanomechanics Department of Civil Environmental and Mechanical Engineering University of Trento School of Engineering and Materials Science Queen Mary University of London Ket Lab Italian Space Agency Via del Politecnico snc

Combining the elastica theory, finite element (fE) analysis, and a geometrical topological experiment, we studied the mechanical behavior of a ring subjected to multi-pairs of evenly distributed eq.al radial forces by looking at its seven distinct states. The results showed that the theoretical predictions of the ring deformation and strain energy matched the fE results very well, and that the ring deformations were comparable to the topological experiment. Moreover, no matter whether the ring was compressed or tensioned by N-pairs of forces, the ring always tended to be regular polygons with 2N sides as the force increased, and a proper compressive force deformed the ring into exq.isite flower-like patterns. The present study solves a basic mechanical problem of a ring subjected to lateral forces, which can be useful for studying the relevant mechanical behavior of ring structures from the nano- to the macro-scale.

关键词： Ring structures Mechanical properties Shape Strain energy

A Study on the Dose-Response Relationship between Asbestos Exposure Level and Asbestosis among Workers in a Chinese Chrysotile Product factory

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Biomedical and Environmental Sciences 1990年第1期3卷 90-98页

作者： J. q. HUAng Institute of Preventive Medicine Shanghai Medical University Shanghai 200032 China

The dose-response relationship for asbestos exposure in a chrysotile product factory was studied. The past gravimetric dust concentration values, obtained from different worksites, were converted into fiber concentration values according to conversion factors that were worked out by simultaneous sampling in this study. The conversions were made so that exposure could be expressed in fiber-years (f-yr). Asbestosis was diagnosed on the basis of chest radiographs and occupational histories. Cumulative dust exposure (f-yr) was calculated up to the date of diagnosis for asbestosis patients, and up to September 1982 for the remaining workers. A dose-response relationship expressed as fiber-years exposed vs cumulative prevalence of asbestosis was established by the life table method on the basis of these data. Predicted 3 and 1% prevalence of asbestosis corresponded to 43 and 22 f-yr exposure, respectively. Considering that a worker can work for 35 years, these doses are commensurate with dust concentrations of 1.22 and 0.63 f/ml, respectively. It is recommended that 1 f/ml be taken as the maximum allowable concentration of airborne asbestos dust for the workplace with an anticipated prevalence of about 2% asbestosis after 35 years of exposure. 1990 Academic Press, Inc.

关键词： A Study on the Dose-Response Relationship between Asbestos Exposure Level and Asbestosis among Workers in a Chinese Chrysotile Product factory

INVESTIGATION Of WO3-DOPED TiO2 fILM COMPOSITE PHOTOCATALYST

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Acta Metallurgica Sinica(English Letters) 2004年第3期17卷 263-268页

作者： q.f. Meng K.R. Liu L. Jiang q. Han J.S. Chen X.J. Wei School of Materials & Metallurgy Northeastern University Shenyang 110004 ChinaSchool of Materials & MetallurgyNortheastern University Shenyang 110004 ChinaSchool of Materials & MetallurgyNortheastern University Shenyang 110004 ChinaSchool of Materials & MetallurgyNortheastern University Shenyang 110004 ChinaSchool of Materials & MetallurgyNortheastern University Shenyang 110004 ChinaSchool of Materials & MetallurgyNortheastern University Shenyang 110004 China

The nano--crystal composite WO_3-TiO_2 photocatalyst was prepared by ultrasonic as-sisted sol--gel process. The effects of various factors, such as the crystal form, thesubstrates, the pH, the dissolved oxygen and the ultrasonic on the photocatalytic ac-tivity were investigated in view of the photodegradation of Rhodamine B. The resultsshow that the crystal form of WO_3-TiO_2 film with highest photocatalytic activity isrutile. The introduction of ultrasonic to the course of preparation can accelerate thedeposit time of the sol and increase the photocatalytic activity significantly in view ofthe highest photodegradation of Rhodamine B being 72.7% in 5 hours. The poroustitanium plate is the most suitable substrate in four kinds of investigated materials.Meanwhile the smaller the pH and the higher the concentration of the dissolved oxygenin the solution is, the higher the photodegradation is.

关键词： ultrasonic sol-gel process photocatalytic photodegradation

Investigation of protein-styrene oxide adducts as a molecular biomarker of human exposed to styrene

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Journal of Environmental Sciences 2001年第4期13卷 391-397页

作者： Liu, S.-f. fang, q.-M. Jin, Z.-L. Rappaport, M.S. Res. Cntr. Eco-Environmental Sci. Chinese Academy of Sciences Beijing 100085 China

Hemoglobin-styrene oxide adducts in blood have been studied as a molecular biomarker of worker exposed to styrene. Determination of protein-styrene oxide adducts in different biological samples with modified Raney-Ni procedure is described in this paper. The following biological samples have been investigated: fresh rat blood reacted with styrene oxide in vitro: rat blood reacted with styrene or styrene oxide in vivo: vein blood from workers exposed to styrene in two factories. The data showed that there was a good linear dose-response relationship between reacting dose of styrene oxide or styrene and amount of protein-styrene oxide adducts in both in vitro and in vivo experiments. for human samples, a dose-response relationship between protein adducts and styrene exposure can be found in glass fiber factory, but not in piano manufacture plant.

关键词： Blood Drug dosage Glass fibers Hemoglobin Manufacture Oxides Proteins Styrene

full-band error control and crack-free surface fabrication techniq.es for ultra-precision fly cutting of large-aperture KDP crystals

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frontiers of Mechanical Engineering 2017年第2期12卷 193-202页

作者： f. H. zhAng S. f. WAng C. H. AN J. WAng q. XU Department of Mechanical Engineering Harbin Institute of TechnologyHarbin 150001 China Chengdu fine Optical Engineering Research Center Chengdu 610041China

Large-aperture potassium dihydrogen phos- phate （KDP） crystals are widely used in the laser path of inertial confinement fusion （ICf） systems. The most common method of manufacturing half-meter KDP crystals is ultra-precision fly cutting. When processing KDP crystals by ultra-precision fly cutting, the dynamic characteristics of the fly cutting machine and fluctuations in the fly cutting environment are translated into surface errors at different spatial freq.ency bands. These machin- ing errors should be suppressed effectively to guarantee that KDP crystals meet the full-band machining accuracy specified in the evaluation index. In this study, the anisotropic machinability of KDP crystals and the causes of typical surface errors in ultra-precision fly cutting of the material are investigated. The structures of the fly cutting machine and existing processing parameters are optimized to improve the machined surface q.ality. The findings are theoretically and practically important in the development of high-energy laser systems in China.

关键词： ultra-precision fly cutting large-aperture KDP crystals spatial freq.ency processing error

On a Class of Constacyclic Codes of Length 4p^8 over fpm[u]/〈 u^a 〉

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Algebra Colloq.ium 2019年第2期26卷 181-194页

作者： Hai q. Dinh Bac T. nguyen Songsak Sriboonchitta Division of Computational Mathematics and Engineering Institute for Computational Science Ton Due Thang University Ho Chi Minh City Vietnam faculty of Mathematics and Statistics Ton Due Thang University Ho Chi Minh City Vietnam nguyen Tat Thanh University Ho Chi Minh City Vietnam Department of Basic Sciences University of Economics and Business Administration Thai Nguyen University Thai Nguyen Province Vietnam faculty of Economics Chiang Mai University Chiang Mai 52000 Thailand

for any odd prime p such that p^m ≡ 3 (mod 4), consider all units Λ of the finite commutative chain ring Ra=fpm[u]/〈u^a〉=fp^m+ufp^m+…+u^a1fp^m that have the form Λ=Λ0 + uΛ1 ++ u^a1 Λa1, where Λ0,Λ1,…,Λa1 p^m,Λ0 ≠ 0,Λ1 ≠ 0. The class of Λ-constacyclic codes of length 4p^s over a is investigated. If the unit Λ is a sq.are, each Λ-constacyclic code of length 4p^s is expressed as a direct sum of a λ-constacyclic code and a λ-constacyclic code of length 2p^s. In the main case that the unit Λ is not a sq.are, we prove that the polynomial x^4 λ0 can be decomposed as a product of two q.adratic irreducible and monic coprime factors, where λ^p^s0=Λ0. from this, the ambient ring Ra[x]/is proven to be a principal ideal ring, whose maximal ideals are and , where λ0 =4η^4. We also give the uniq.e self-dual Type 1 Λ-constacyclic codes of length 4p^s over a. furthermore, conditions for a Type 1 Λ-constacyclic code to be self-orthogonal and dual-containing are provided.

关键词： constacyclic codes dual codes chain rings