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Density enhancement mechanism of upwind schemes for low Mach number flows

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Acta Mechanica Sinica 2018年第3期34卷 431-445页

作者： Bo-xi Lin Chao yan Shu-Sheng Chen School of Aeronautic Science and Engineering Beihang University

Many all-speed Roe schemes have been proposed to improve performance in terms of low speeds. Among them, the F-Roe and T-D-Roe schemes have been found to get incorrect density fluctuation in low Mach flows, which is expected to be with the square of Mach number. Asymptotic analysis presents the mechanism of how the density fluctuation problem relates to the incorrect order of terms in the energy equation paU△U. It is known that changing the upwind scheme coefficients of the pressure-difference dissipation term DP and the velocity-difference dissipation term in the momentum equation DPU to the order of O （c- 1） and O（c0） can improve the level of pressure and velocity accuracy at low speeds. This paper shows that corresponding changes in energy equation can also improve the density accuracy in low speeds. We apply this modification to a recently proposed scheme, TV-MAS, to get a new scheme, TV-MAS2. Unsteady Gresho vortex flow, double shear-layer flow, low Mach number flows over the inviscid cylinder, and NACA0012 airfoil show that energy equation modification in these schemes can obtain the expected square Ma scaling of density fluctuations, which is in good agreement with corresponding asymptotic analysis. Therefore, this density correction is expected to be widely implemented into allspeed compressible flow solvers.

关键词： Energy equation Density fluctuation Roe TV-MAS Low speeds All speeds Computational fluid dynamics

Optimization of extraction of phenolics from leaves of Ficus virens

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2013年第10期14卷 903-915页

作者： xiao-xin CHEN xiao-bing WU Wei-ming CHAI Hui-ling FENG yan SHI Han-tao ZHOU Qing-xi CHEN Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems School of Life Sciences Xiamen University

In this research,the conditions for extraction of phenolics from leaves of Ficus virens were optimized using response surface methodology(RSM).The extraction abilities of phenolics(EAP) and flavonoids(EAF),the 2,2-diphenyl-1-pierylhydrazyl(DPPH) free-radical scavenging potential,and the ferric reducing/antioxidant power(FRAP) were used as quality *** results of single-factor experiments showed that temperature,ethanol concentration,extraction time,and the number of extraction cycles were the main influencing variables,and these provided key information for the central composite *** results of RSM fitted well to a second degree polynomial model and more than 98% of the variability was *** ideal extraction conditions for EAP,EAF,DPPH free-radical scavenging potential,and FRAP were *** the four quality indicators overall,the ideal extraction conditions were 58% ethanol at 57 °C for 37 min with three extraction *** the ideal extraction conditions,the values of EAP,EAF,DPPH free-radical scavenging potential,and FRAP were 5.72%,3.09%,58.88 mg ascorbic acid equivalent(AAE)/g dry weight(DW),and 15.86 mg AAE/g DW,*** addition,linear correlations were observed between EAP,EAF,and antioxidant potential.

关键词： Ficus virens Phenolics Flavonoids Antioxidants Response surface methodology(RSM)

The correlation of serum PDGF and Ang-2 contents with atherosclerotic plaque features in patients with coronary heart disease

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Journal of Hainan Medical University 2017年第8期23卷 39-42页

作者： yan-bing xi Clinical Laboratory Department General Hospital of Hubei Jianghan OilfieldQianjiang CityHubei Province433121

Objective:To study the correlation of serum PDGF and Ang-2 contents with atherosclerotic plaque features in patients with coronary heart ***: A total of 80 patients with coronary heart disease who were treated in our hospital between January 2013 and April 2016 were collected as the observation group, and 50 healthy subjects who received medical examination in our hospital during the same period were selected as the normal control group. Serum PDGF and Ang-2 contents of two groups of patients were detected, and the observation group were further divided into the high PDGF group and low PDGF group (n = 40) as well as the high Ang-2 group and low Ang-2 group (n = 40) according to the median of PDGF and Ang-2 contents. Ultrasonic contrast technology was used to assess the atherosclerotic plaque characteristics in patients with coronary heart ***: Serum PDGF and Ang-2 contents of observation group were significantly higher than those of control group;ultrasound parameters P and AUC levels of high PDGF group were higher than those of low PDGF group while Tp and MTT levels were lower than those of low PDGF group;ultrasound parameters P and AUC levels of high Ang-2 group were higher than those of low Ang-2 group while Tp and MTT levels were lower than those of low Ang-2 ***:Serum PDGF and Ang-2 contents increase in patients with coronary heart disease and are negatively correlated with the atherosclerotic plaque stability.

关键词： Coronary heart disease Platelet-derived growth factor Angiogenin 2 Atherosclerotic plaque

Intervention effect of traditional Chinese medicine Yi Tang Kang on metabolic syndrome of spleen deficiency

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Asian Pacific Journal of Tropical Medicine 2015年第2期8卷 162-168页

作者： xiao-xi Liu yan Shi Department of endocrinology Affiliated Hospital of Liaoning University of TMC

Objective:To investigate effects of herbal compound Yi Tang Kang on the spleen deficiency metabolic ***:Forty male Wistar rats were randomly divided into two groups:the normal control group and the MS spleen deficiency syndrome *** control group rats were fed with standard diet and water,while MS spleen deficiency syndrome group with high fat diet and low dose intraperitoneal injection of *** swam to the endurance *** 12 weeks,the MS spleen deficiency syndrome group was randomly divided into two groups,with 13 rats in each *** in model group were fed with high fat diet and conlinuouly administered with daily saline,and rats in intervention group with high fat diet were trated with traditional Chinese medicines Yi Tang Kang by gavage,2 mL/200 g at the same lime every day.10 weeks later,the expression of serum proteomics was investigated through abdominal aortic puncture and separation of serum,using isotope labeling technique,high performance liquid chromatography and four bar-Orbitrap mass ***:After treatment with traditional Chinese medicine yitangkang,in the model group,important carboxylesterase and retinal guanylate cyclase 2 precursor were *** for intervention group,these indesxes were raised,but immunoglobulin IgG,carnitine acetyltransferase,tubulin beta-5,and Gan Lu sugar binding protein C were *** the same time,some new biological active substances,such as protein tyrosine kinase,beta glucosidase were also ***:Traditional Chinese medicines Yi Tang Kang could regulate glucose and lipid metabolism in rats with spleen deficiency syndrome.

关键词： Spleen deficiency syndrome Yi Tang Kang Proteomics

A high propylene productivity over B2O3/SiO2@honeycomb cordierite catalyst for oxidative dehydrogenation of propane

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Chinese Journal of Chemical Engineering 2020年第11期28卷 2778-2784页

作者： Yuxi Zhou yangWang Wenduo Lu bing yan Anhui Lu State Key Laboratory of Fine Chemicals Liaoning Key Laboratory for Catalytic Conversion Carbon ResourcesSchool of Chemical EngineeringDalian University of TechnologyDalian 116024China

Boron-based metal-free catalysts for oxidative dehydrogenation of propane(ODHP)have drawn great attention in both academia and industry due to their impressive activity and olefin ***,the SiO2 and B2O3 sequentially coated honeycomb cordierite catalyst is designed by a two-step wash-coat method with different B2O3 loadings(0.1%–10%)and calcination temperatures(600,700,800℃).SiO2 obtained by TEOS hydrolysis acts as a media layer to bridge the cordierite substrate and boron oxide via abundant Si\\OH *** welldeveloped straight channels of honeycomb cordierite make it possible to carry out the reactor under high gas hourly space velocity(GHSV)and the thin wash-coated B2O3 layer can effectively facilitate the pore diffusion on the *** prepared B2O3/SiO2@HC monolithic catalyst exhibits good catalytic performance at low boron oxide loading and achieves excellent propylene selectivity(86.0%),olefin selectivity(97.6%,propylene and ethylene)and negligible CO2(0.1%)at 16.9%propane conversion under high GHSV of 345,600 ml·(g B2O3)^-1·h^-1,leading to a high propylene space time yield of 15.7 g C3H6·(g B2O3)^-1·h^-1 by suppressing the *** obtained results strongly indicate that the boron-based monolithic catalyst can be properly fabricated to warrant the high activity and high throughput with its high gas/surface ratio and straight channels.

关键词： Oxidative dehydrogenation Boron-based catalyst Alkane Propylene Monolith High GHSV

Effects of thermal treatment on physical and mechanical characteristics of coal rock

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Journal of Central South University 2016年第9期23卷 2336-2345页

作者： YIN Tu-bing WANG Pin LI xi-bing SHU Rong-hua YE Zhou-yuan School of Resources and Safety Engineering Central South University Changsha 410083 China School of Energy and Safety Engineering Hunan University of Science and Technology Xiangtan 411201 China

To study the physical and mechanical properties of coal rock after treatment at different temperatures under impact loading, dynamic compression experiments were conducted by using a split Hopkinson pressure bar(SHPB). The stress–strain curves of specimens under impact loading were obtained, and then four indexes affected by temperature were analyzed in the experiment: the longitudinal wave velocity, elastic modulus, peak stress and peak strain. Among these indexes, the elastic modulus was utilized to express the specimens' damage characteristics. The results show that the stress–strain curves under impact loading lack the stage of micro-fissure closure and the slope of the elastic deformation stage is higher than that under static loading. Due to the dynamic loading effect, the peak stress increases while peak strain decreases. The dynamic mechanical properties of coal rock show obvious temperature effects. The longitudinal wave velocity, elastic modulus and peak stress all decrease to different extents with increasing temperature, while the peak strain increases continuously. During the whole heating process, the thermal damage value continues to increase linearly, which indicates that the internal structure of coal rock is gradually damaged by high temperature.

关键词： rock mechanical property split Hopkinson pressure bar (SHPB) high temperature coal rock dynamic mechanical property

Extraskeletal Chondroma in the Popliteal Region: A Case Report

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Chinese Medical Sciences Journal 2015年第4期30卷 270-272页

作者： bing-yan Mao Department of Orthopaedic Surgery Shimen Hospital of Changsha Medical University

EXTRASKELETAL chondroma is a rare benigntumor that usually develops in the soft tissue,which commonly occurs in the limbs of adults andgenerally presents as painless masses without thesurrounding tissues involvement. The diagnosis mainlydepends on computed tomography, magnetic resonanceimaging （MRI） examination, and postoperative pathologicalexamination. This paper reports a case of extraskeletalchondroma in the popliteal region.

关键词： extraskeletal chondroma popliteal region

Solitary Wave and Non-traveling Wave Solutions to Two Nonlinear Evolution Equations

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Communications in Theoretical Physics 2005年第3X期44卷 479-482页

作者： yan Zhi-Lian LIU xi-Qiang School of Mathematical Sciences Liaocheng University Liaocheng 252059 China

By applying the extended homogeneous balance method, we find some new explicit solutions to two nonlinear evolution equations, which include n-resonance plane solitary wave and non-traveling wave solutions.

关键词： approximate equations for long water waves variant Boussinesq equations non-traveling wave solution solitary wave solution

Modification of Bertrand’s Theorem and Extended Runge-Lenz Vector

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Chinese Physics Letters 1999年第11期16卷 781-783页

作者： WU Zuo-bing ZENG Jin-yan Department of Physics Peking UniversityBeijing 100871 Laboratory for Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100080

It is shown that for a particle with suitable angular momenta in the screened Coulomb potential or isotropic harmonic potential, there still exist closed orbits rather than ellipse, characterized by the conserved aphelion and perihelion vectors, i.e. extended Runge-Lenz vector, which implies a higher dynamical symmetry than the geometrical symmetry O_(3). The closeness of a planar orbit implies the radial and angular motional frequencies are commensurable.

关键词： Runge implies symmetry