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The equilibrium stability for a smooth and discontinuous oscillator with dry friction

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Acta Mechanica Sinica 2016年第2期32卷 309-319页

作者： zhi-xin li Qing-Jie Cao Alain Léger School of Astronautics Centre for Nonlinear Dynamics Research Harbin Institute of Technology Harbin 150001 China Laboratoire de Mecanique et d' Acoustique CNRS 31 Chemin Joseph Aiguier 13402 Marseille Cedex 20 France

In this paper,we investigate the equilibrium stability of a Filippov-type system having multiple stick regions based upon a smooth and discontinuous（SD） oscillator with dry *** sets of equilibrium states of the system are analyzed together with Coulomb friction conditions in both（ f_n,f_s） and（x,˙x） *** the stability analysis,Lyapunov functions are constructed to derive the instability for the equilibrium set of the hyperbolic type and La Salle＇s invariance principle is employed to obtain the stability of the nonhyperbolic *** demonstrates the existence of a thick stable manifold and the interior stability of the hyperbolic equilibrium set due to the attractive sliding mode of the Filippov property,and also shows that the unstable manifolds of the hyperbolic-type are that of the endpoints with their saddle *** calculations show a good agreement with the theoretical analysis and an excellent efficien y of the approach for equilibrium states in this particular Filippov ***,the equilibrium bifurcations are presented to demonstrate the transition between the smooth and the discontinuous regimes.

关键词： SD oscillator Equilibrium set Dry friction Coulomb’s cone

Analysis of the periodic solutions of a smooth and discontinuous oscillator

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Acta Mechanica Sinica 2013年第4期29卷 575-582页

作者： zhi-xin li Qing-Jie Cao Marian Wiercigroch Alain Léger Centre for Nonlinear Dynamics Research Harbin Institute of Technology School of Astronautics Centre for Applied Dynamics Research School of Engineering University of Aberdeen King's College Laboratoire de Mécanique et d' Acoustique CNRS 31 Chemin Joseph Aiguier 13402 Marseille Cedex 20 France

In this paper, the periodic solutions of the smooth and discontinuous （SD） oscillator, which is a strongly irra- tional nonlinear system are discussed for the system having a viscous damping and an external harmonic excitation. A four dimensional averaging method is employed by using the complete Jacobian elliptic integrals directly to obtain the perturbed primary responses which bifurcate from both the hyperbolic saddle and the non-hyperbolic centres of the un- perturbed system. The stability of these periodic solutions is analysed by examining the four dimensional averaged equa- tion using Lyapunov method. The results presented herein this paper are valid for both smooth （e 〉 0） and discontin- uous （ce = 0） stages providing the answer to the question why the averaging theorem spectacularly fails for the case of medium strength of external forcing in the Duffing system analysed by Holmes. Numerical calculations show a good agreement with the theoretical predictions and an excellent efficiency of the analysis for this particular system, which also suggests the analysis is applicable to strongly nonlinear systems.

关键词： SD oscillator ~ Averaging method. Periodic so-lution ~ Irrational nonlinearity ~ Elliptic integral

Influence of Edge Rolling Reduction on Plate-Edge Stress Distribution During Finish Rolling

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Journal of Iron and Steel Research International 2009年第1期16卷 22-26页

作者： YU Hai-liang liU Xiang-hua CHEN li-qing li Chang-sheng zhi Ying li xin-wen The State Key Laboratory of Roiling and Automation Northeastern University Shenyang 110004 Liaoning China

Dimensions of one kind of stainless steel plate before finish rolling were obtained through analysis of the rough rolling processes by finite element method and updated geometrical method. The FE models of finish rolling process with a front edge roll were built, and influences of the edge rolling reduction on the stress change in the plate edge during finish rolling were analyzed. The results show that when the edge rolling reduction is increased from 0 mm to 2 mm, the compressive stress in plate corner clearly increases in edge rolling process, and the zone of tensile stress during whole rolling decreases; when the edge rolling reduction is increased from 2 mm to 5 ram, the compressive stress in the plate corner seldom changes, and the compressive stress decreases after the horizontal rolling.

关键词： edge rolling reduction stress FEM finish rolling

Remove of Heavy Metals（Cu2＋, Pb2＋, Zn2＋ and Cd2＋） in Water Through Modified Diatomite

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Chemical Research in Chinese Universities 2013年第3期29卷 445-448页

作者： liU Jia WANG Hong-liang LU Chun-xin liU Han-fei GUO zhi-xin KANG Chun-li Key Laboratory of Groundwater Resources and Environment Ministry of Education Jilin University Changchun 130012 P. R. China

At present, heavy metal pollution has become a major environmental problem, influencing the survival of human and other creatures. Developing heavy metal ion adsorbents, which are environment friendly, of low cost and good performance is one of the effective means to solve heavy metal pollution. Rich low-grade diatomite mineral, as raw material, was modified with calcium carbonate to improve the adsorption properties of diatomite for heavy metal ions. The effects of dosage（m）, pH, adsorbing time（t）, temperature（T） and concentration of adsorbent（c） on the removal rate of heavy metal ions（Cu2＋, Pb2＋, Zn2＋ and Cd2＋） were studied. The results show that under the suitable conditions, T=15 ℃, c=1.5 mmol/L, m=10 g/L, t=60 min, in a weak acid environment, the removal effect of the four kinds of metal ions by modified diatomite is the best.

关键词： Diatomite Heavy metal Modification Adsorption

Impact of early refined nursing program on prognosis of middleaged and elderly patients with cognitive dysfunction combined with cerebral infarction

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World Journal of Psychiatry 2024年第7期14卷 1034-1042页

作者： Hui-lian Xiong zhi-xin li xin Lu Yan-Hua Lu Ping Zhong Ganzhou City Central Blood Station Ganzhou 341000Jiangxi ProvinceChina Department of Rehabilitation Medicine Ganzhou People's HospitalGanzhou 341000Jiangxi ProvinceChina

BACKGROUND Cerebral infarction is a local or extensive necrosis of brain ***,the corresponding neurological deficits *** incidence of cerebrovascular diseases in China is increasing *** the onset of cerebrovascular disease,the most common sequelae include movement disorders,language disorders,and cognitive *** To investigate the effect of early refined nursing program on the prognosis of middle-aged and elderly patients with cerebral infarction combined with cognitive *** A retrospective study was conducted to divide 60 patients with cerebral infarction and cognitive impairment into an experimental group(n=32)and a control group(n=28).The experimental group received early intensive care every day,and the control group received daily routine *** scores of the Mini-Mental State Examination(MMSE)and the Trail Making Test(TMT),as well as the latency and amplitude of the event-related potential P300,were used as main indicators to evaluate changes in cognitive function,and changes in BDNF,TGF-β,and GDNF expression were used as secondary *** Both groups experienced notable enhancements in MMSE scores,with the experi-mental group demonstrating higher scores than the control group(experimental:28.75±2.31;control:25.84±2.87).Moreover,reductions in TMT-A and TMT-B scores were observed in both groups(experimental:TMT-A 52.36±6.18,TMT-B 98.47±10.23;control:TMT-A 61.48±7.92,TMT-B 112.63±12.55),with the experimental group displaying lower scores.P300 Latency decreased(experimental:270.63 ms±14.28 ms;control:285.72 ms±16.45 ms),while amplitude increased(experimental:7.82μV±1.05μV;control:6.35μV±0.98μV)significantly in both groups,with superior outcomes in the experimental ***,the levels of the growth factors BDNF,TGF-β1,and GDNF surged(experimental:BDNF 48.37 ng/mL±5.62 ng/mL,TGF-β152.14 pg/mL±4.28 pg/mL,GDNF 34.76 ng/mL±3.89 ng/mL;control:BDNF 42.58 ng/mL±4.73 ng/mL,TGF-β146.23 pg/m

关键词： Early refined nursing program Cerebral infraction Cognitive impairment Psychiatry Trajectory test

Comparisons of Three Recurrent Selection Methods in the Improvement of Maize Populations

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Agricultural Sciences in China 2007年第6期6卷 657-664页

作者： PENG Ze-bin li Ming-shun liU xin-zhi li Jun-qiang Institute of Crop Sciences Chinese Academy of Agricultural Sciences Beijing 100081 P.R.China

The maize population Csyn 4 was improved for three cycles with three recurrent selection methods MS1, MS1-HS, and MHSRRS in northern China. A total of 40 NC Ⅱ testcrosses were made by four testers with Csyn 4 and 10 improved populations, which were evaluated in four environments in the cropping season of 2005. Analysis of variance indicated a significant progress （P〈 0.05） in yield and other chief agronomic traits in the improved populations and testcrosses, demonstrating that the three recurrent selection methods were effective for increasing grain yield of testcrosses and improvement of general combining ability in maize population. The average grain yield increase of population Csyn 4 in MS1, MS1-HS, and MHSRRS recurrent selections was 266.7 kg ha^-1 （5.3%）, 288.0 kg ha^-1 （5.7%）, and 231.3 kg ha^-1 （4.6%） per cycle, while the grain yield of S 1 progeny of population for Csyn 4 was increased by 420.0 kg ha^-1 （10.9%）, 376.0 kg ha^-1 （9.8%）, and 414.7 kg ha^-1 （10.8%） per cycle in MS1, MS1-HS, and MHSRRS recurrent selections, respectively. linear responses （b） in the MS1, MS1-HS, and MHSRRS recurrent selections were the same as the realized responses of the selection （G） for grain yield increase of Csyn 4 and S1 progeny of the populations. The grain yield of testcrosses increased by 3.3-5.2% on average per cycle. The value of heterosis did not display any differences amongst the different cycles of selections. The GCA for yield component traits of population Csyn 4 was improved significantly by means of three selection methods, whereas the GCA for plant height, ear height, days to silking, and days to pollen did not show significant increase in the recurrent selections. GCA for the number of tassel branches were decreased in the selections, while GCA for the number of plant leaves were increased, but the difference was not significant.

关键词： maize (Zea mays L.) population improvement recurrent selection modified S 1 family selection (MS 1),modified S 1 family-half-sib family combining selection (MS 1-HS) modified half-sib reciprocal recurrentselection (MHSRRS)

An end-to-end anastomosis model of guinea pig bile duct:A 6-mo observation

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World Journal of Gastroenterology 2011年第6期17卷 789-795页

作者： Xiao-Qing Zhang Yuan-Hu Tian zhi Xu li-xin Wang Chun-Sheng Hou Xiao-Feng ling Xiao-Si Zhou Department of General Surgery Peking University Third Hospital Beijing 100191 China

AIM:To establish the end-to-end anastomosis (EEA) model of guinea pig bile duct and evaluate the healing process of bile ***:Thirty-two male guinea pigs were randomly divided into control group,2-,3-,and 6-mo groups after establishment of EEA ***,immunohistochemical and serologic tests as well as measurement of bile contents were *** bile duct diameter and the diameter ratio (DR) were measured to assess the formation of relative ***:Acute and chronic inflammatory reactions occurred throughout the healing process of bile *** test and bile content measurement showed no formation of persistent stricture in 6-mo *** DR revealed a transient formation of relative stricture in 2-mo group in comparation to control group (2.94 ± 0.17 vs 1.89 ± 0.27,P=0.004).However,this relative stricture was released in 6-mo group (2.14 ± 0.18,P=0.440).CONCLUSION:A simple and reliable EEA model of guinea pig bile duct can be established with a good reproducibility and a satisfactory survival rate.

关键词： Animal model Guinea pig Anastomosis Common bile duct Wound healing

Integration of Theory and Practice in Medical Morphology Curriculum in Postgraduate Training:A Flipped Classroom and Case-based Learning Exercise

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Current Medical Science 2023年第4期43卷 741-748页

作者： Xi-min HU zhi-xin li Jing DENG Yang HAN Shuang LU Qi ZHANG Zi-qiang LUO Kun XIONG Department of Anatomy and Neurobiology School of Basic Medical ScienceCentral South UniversityChangsha 410000China Clinical Medicine Eight-year Program 02 Class18 GradeXiangya School of MedicineCentral South UniversityChangsha 410000China Department of Epidemiology and Health Statistics Xiangya School of Public HealthCentral South UniversityChangsha 410000China Department of Physiology School of Basic Medical ScienceCentral South UniversityChangsha 410008China Hunan Key Laboratory of Ophthalmology Changsha 410000China Key Laboratory of Emergency and Trauma Ministry of EducationCollege of Emergency and TraumaHainan Medical UniversityHaikou 016000China

Objective:The integration of training in theory and practice across the medical education spectrum is being encouraged to increase student understanding and skills in the *** study aimed to determine the deciding factors that drive students'perceived advantages in class to improve precision education and the teaching ***:A mixed strategy of an existing flipped classroom(FC)and a case-based learning(CBL)model was conducted in a medical morphology curriculum for 575 postgraduate *** subjective learning evaluation of the individuals(learning time,engagement,study interest and concentration,and professional integration)was collected and analyzed after FC-CBL model ***:The results from the general evaluation showed promising results of the medical morphology in the FC-CBL *** felt more engaged by instructors in person and benefited in terms of time-saving,flexible arrangements,and professional *** study contributed to the FC-CBL model in Research Design in postgraduate training in 4 categories:1)advancing a guideline of precision teaching according to individual characteristics;2)revealing whether a learning background is needed for a Research Design course to guide setting up a preliminary course;3)understanding the perceived advantages and their interfaces;and 4)barriers and/or improvement to implement the FC-CBL model in the Research Design class,such as a richer description of e-learning and hands-on ***:Undertaking a FC-CBL combined model could be a useful addition to pedagogy for medical morphology learning in postgraduate training.

关键词： flipped classroom case-based learning medical morphology curriculum research design postgraduate

A Novel Enzyme-Responded Controlled Release Electrochemical Biosensor for Hyaluronidase Activity Detection

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Journal of Analysis and Testing 2021年第1期5卷 69-75页

作者： zhi-xin li Jia-Lu Zhang Jian Wang Fang Luo Bin Qiu Long-Hua Guo Zhen-Yu lin Ministry of Education Key Laboratory for Analytical Science of Food Safety and Biology Fujian Provincial Key Laboratory of Analysis and Detection for Food SafetyCollege of ChemistryFuzhou UniversityFuzhou 350116China College of Biological Chemical Sciences and EngineeringJiaxing UniversityJiaxing 314001China

Hyaluronidase(HAase)has been regarded as one of the potential cancer *** this study,a novel enzyme-responded controlled release electrochemical biosensor has been constructed for HAase *** blue(MB)can be adsorbed on hyaluronic acid(HA)to form macromolecular HA–MB complex first through electrostatic interaction between anionic HA and positively charged *** prepared complex cannot be filtered out through centrifugal ultrafiltration,and small electrochemical signal can be recorded from the *** the help of HAase,HA–MB complex can be cleaved into small pieces through enzyme *** small pieces of HA–MB complex can be easily released from the macromolecular HA–MB complex to the ultrafiltrate by centrifugal ***,the enhanced electrochemical signal from MB can be detected in the above-mentioned *** enhanced diff erential pulse voltammetric response of the system has a linear relationship with HAase concentration in the range of 4.0–60 U·mL^(-1),with the limit of detection of 0.28 U·mL^(-1).The developed strategy has been successfully applied to detect HAase activity in urine samples.

关键词： Electrostatic interaction Controlled release Hyaluronic acid Hyaluronidase Methylene blue