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Nonclassical Potential Symmetries and New Explicit Solutions of Burgers Equation

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Communications in Theoretical Physics 2005年第1X期44卷 11-14页

作者： QINMao-chang MEIFeng-xiang XUXue-Jun DepartmentofAppliedMechanics BeijingInstituteofTechnologyBeijing100081China

A new method is used to determine the nonclassical potential symmetry generators of Burgers *** classes of new explicit solutions, which cannot be obtained by Lie symmetry group of Burgers equation or its integrated e... 详细信息

关键词：非经典对称 Burgers方程直接法 Lie对称

Two New Steroidal Saponins from Tacca plantaginea

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Chinese Chemical Letters 2002年第7期13卷 633-636页

作者： Hai Yang LIU chang xiang CHEN Laboratory of Phytochemistry Kunming Insitute of BotanyChinese Academy of ScienceKunming 650204

Two new C27 steroidal glycosides, named taccaoside A (1) and B (2), were isolated from the traditional Chinese herb Tacca plantaginea. The spectroscopic and chemical evidences revealed their structures to be 26-O--D-glucopyranosyl-(25R)-3?26-dihydroxy furost-5,20-diene -3-O-[?L-rhamnopyranosyl(12)]-[?L-rhamnopyranosyl(13)]--D-glucopyranoside (1) and 26-O--D-glucopyranosyl-(25R)-3?26-dihydroxy furost-5,20-diene-3-O-[?L-rhamnopyranosyl- (12)]-[?D-glucopyranosyl(13)--L-rhamnopyranosyl(13)]--D-glucopyranoside (2), res- pectively.

关键词： Tacca plantaginea steroidal saponins taccaoside A and B.

A FRACTIONAL CRITICAL PROBLEM WITH SHIFTING SUBCRITICAL PERTURBATION

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Acta Mathematica Scientia 2022年第3期42卷 1113-1124页

作者： Qi LI chang-Lin xiang College of Science Wuhan University of Science and TechnologyWuhan 430065China Three Gorges Mathematical Research Center China Three Gorges UniversityYichang 443002China

In this paper,we consider a class of fractional problem with subcritical perturbation on a bounded domain as follows:(P_(k)){(−△)^(s)u = g(x)[(u − k)+]^(q−1) +u^(2^(∗)_(s)−1), x ∈Ω ,u > 0, x∈Ω ,u = 0, x ∈Ω R^(N)\Ω. We prove the existence of nontrivial solutions u_(k) of(P_(k))for each k∈(0,∞).We also investigate the concentration behavior of the solutions u_(k) as k→∞.

关键词： Subcritical perturbation nontrivial solutions concentration

Optimization Design and Performance Analysis of Vehicle Powertrain Mounting System

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Chinese Journal of Mechanical Engineering 2018年第2期31卷 76-88页

作者： Han Zhou Hui Liu Pu Gao chang-Le xiang School of Mechanical Engineering Beijing Institute of Technology National Key Lab of Vehicular Transmission Beijing Institute of Technology

The design strategies for powertrain mounting systems play an important role in the reduction of vehicular vibration and noise. As stiffness and damping elements connecting the transmission system and vehicle body, the rubber mount exhibits better vibration isolation performance than the rigid connection. This paper presents a complete design process of the mounting system, including the vibration decoupling, vibration simulation analysis, topology optimization, and experimental verification. Based on the 6?degrees?of?freedom vibration coupling model of the powertrain mounting system, an optimization algorithm is used to extract the best design parameters of each mount, thus rendering the mounting system fully decoupled and the natural frequency well configured, and the optimal parameters are used to design the mounting system. Subsequently, vibration simulation analysis is applied to the mounting system, considering both transmission and road excitations. According to the results of finite element analysis, the topological structure of the metal frame of the front mount is optimized to improve the strength and dynamic characteristics of the mounting system. Finally, the vibration bench test is used to verify the availability of the optimization design with the analysis of acceleration response and vibration transmissibility of the mounting system. The results show that the vibration isolation performance of the mounting system can be improved effectively using the vibration optimal decoupling method, and the structural modification of the metal frame can well promote the dynamic characteristics of the mounting system.

关键词： Mounting system Optimization algorithm Vibration simulation analysis Topological structure Acceleration response Vibration transmissibility

Two new triterpenoid saponins from Polygala crotalarioides

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Chinese Chemical Letters 2010年第9期21卷 1107-1110页

作者： Yan Hua chang xiang Chen Jun Zhou Key Laboratory for Forest Resources Conservation and Use in the Southwest Mountains of China Ministry of Education Southwest Forestry University Kunming 650224 China State Key Laboratory of Phytochemistry and Plant Resource in West China Kunming Institute of Botany Academia Sinica Kunming 650204 China

Two new oleanane-type saponins,crotalarioside A（1） and crotalarioside B（2）,were isolated from the roots of Polygala *** structures were elucidated on the basis of spectroscopic and chemical evidence.

关键词： Polygala crotalarioides Chemical constituents Oleanane-type saponins

A new eudesmane sesquiterpene glycoside from Parepigynum funingense

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Chinese Chemical Letters 2007年第1期18卷 73-75页

作者： Yan Hua Jun Zhou chang xiang Chen Southwest Forestry College Kunming 650224 China State Key Laboratory of Phytochemistry and Plant Resource in West China Kunming Institute of Botany Academia Sinica Kunming 650204 China

A new eudesmane sesquiterpene glycoside, 1α,6β-dihydroxy-5,10-bis-epi-eudesm-4（15）-ene-6-O-β-D-glucopyranoside （2）, together with a known analogue compound, 1α,6β-dihydroxy-5,10-bis-epi-eudesm-3-ene-6-O-β-D-glucopyranoside （1）, were isolated from the roots of Parepigynumfuningense. The structure of 2 was determined by 1D and 2D NMR spectroscopy. Compound 1 was isolated from this plant for the first time.

关键词： Parepigynum funingense Chemical constituents Eudesmane sesquiterpene

The Existence of Even Cycles with Specific Lengths in Wenger's Graph

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Acta Mathematicae Applicatae Sinica 2008年第2期24卷 281-288页

作者： Jia-yu Shao chang-xiang He Hai-ying Shan Department of Mathematics Tongji University Shanghai 200092 China College of Science University of Shanghai for Science and Technology Shanghai 200093 China

Wenger＇s graph Hm（q） is a q-regular bipartite graph of order 2qm constructed by using the mdimensional vector space Fq^m over the finite field Fq. The existence of the cycles of certain even length plays an important role in the study of the accurate order of the Turan number ex（n; C2m） in extremal graph theory. In this paper, we use the algebraic methods of linear system of equations over the finite field and the “critical zero-sum sequences” to show that： if m ≥ 3, then for any integer l with l ≠ 5, 4 ≤ l ≤ 2ch（Fq）（where ch（Fq） is the character of the finite field Fq） and any vertex v in the Wenger＇s graph Hm（q）, there is a cycle of length 21 in Hm（q） passing through the vertex v.

关键词： Graph cycle finite field vector space linear system of equations

Preparation of PDMS-coated microspheres by sol-gel method for sorptive extraction of PAHs

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Chinese Chemical Letters 2008年第8期19卷 996-999页

作者： chang Guang Yang xiang Juan Ji Xiao Zheng Lan College of Chemistry and Materials Science Shandong Agricultural University Taian 271018 China

In this paper, a novel SPME mode, PDMS-coated solid glass microspheres （SGMs）, were prepared by sol-gel method. Using homemade thermal desorption unit coupled with CGC-FID, six PAHs as model analytes, the performance of the new mode was characterized. The new extractive phase exhibited high thermal stability and satisfactory extraction capability. The detection limits were 0.01-0.045 ng/mL, and the linearity was from 0.5 ng/mL to 96 ng/mL. The R.S.D.s of repeatability for retention time and peak area were all within 0.074% and 6.7%, respectively. The recoveries of the PAHs were 78-127% from the samples taken from river water.

关键词： Sorptive extraction PDMS-coated microspheres Sol-gel PAHs

New Method for Evaluating Thermal Wear of Rolls in Rolling Process

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Journal of Iron and Steel Research International 2008年第6期15卷 52-55页

作者： LI chang-sheng LIU xiang-hua WANG Guo-dong State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China

A new method was developed by a thermal wear machine to evaluate the thermal wear of roils in steel rolling process. The steel strip and rolls were simulated by upper and lower heating disks. The upper heating disk could he kept at a temperature of over 900 ℃ by induction heating. The pressure between the disks as high as 323.2 MPa could be achieved and the slipping rate could be 12. 7 %. The thermal wear of high speed steel （HSS） roll material, the wear rate of the HSS roll, and the SEM morphology of a worn HSS roll surface were investigated. This method was useful and could be employed to simulate friction and wear between strip and roll during the strip rolling process.

关键词： thermal wear roll friction strip rolling induction heating