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JUMPING INSTABILITIES IN THE POST-BUCKLING OF A BEAM ON A PARTIAL NONLINEAR FOUNdATION

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Acta Mechanica Solida Sinica 2013年第5期26卷 500-513页

作者： Yin Zhang kevin d Murphy State Key Laboratory of Nonlinear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences department of Mechanical Engineering University of Connecticut

Mode jumping is an instability phenomenon in the post-buckling region, which causes a sudden change in the equilibrium configuration and is thus harmful to structure. The con- figuration of a partial elastic foundation can directly induce mode coupling from the buckling stage and through the whole post-buckling region. The mode coupling effect due to the configuration of partial foundation on mode jumping is investigated and demonstrated to be an important factor of determining mode jumping. By properly choosing the partial elastic foundation configuration, mode jumping can be avoided.

关键词： instability mode jumping tertiary jumping buckling beam elastic foundation

Tensionless contact of a finite circular plate

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Acta Mechanica Sinica 2012年第5期28卷 1374-1381页

作者： Yin Zhang kevin d.Murphy State Key Laboratory of Nonlinear Mechanics(LNM) Institute of MechanicsChinese Academy of Sciences department of Mechanical Engineering the University of Connecticut

A general formulation is developed for the contact behavior of a finite circular plate with a tensionless elastic foundation. The gap distance between the plate and elastic foundation is incorporated as an important parameter. Unlike the previous models with zero gap distance and large/infinite plate radius, which assumes the lift-off/separation of a flexural plate from its supporting elastic foundation, this study shows that lift-off may not occur. The results show how the contact area varies with the plate radius, boundary conditions and gap distance. When the plate radius becomes large enough and the gap distance is reduced to zero, the converged contact radius close to the previous ones is obtained.

关键词： Tensionless contact Elastic foundation Plate Lift-off

Tensionless contact of a finite beam:Concentrated load inside and outside the contact zone

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Acta Mechanica Sinica 2013年第6期29卷 836-839页

作者： Yin Zhang kevin d.Murphy State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of Sciences department of Mechanical Engineering University of ConnecticutStorrsCT 06268USA

For a finite beam with a nonzero gap distance, an asymmetric concentrated load can be either inside or outside of the contact zone. A new governing equation is given for the case of a concentrated load outside the contact zone. By numerically solving the left-side and right-side contact lengths of the beam, a criterion is established to determine whether the concentrated load is inside or outside the contact zone. A more general approach on the tensionless contact of a beam is thus presented.

关键词： Tensionless contact Lift-off Beam

Testosterone and cardiovascular disease in men

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Asian Journal of Andrology 2012年第3期14卷 428-435,I0007页

作者： Paul d Morris kevin S Channer Sheffield Teaching Hospital NHS Trust Sheffield S10 2JF UK

despite regional variations in the prevalence of coronary artery disease （CAd）, men are consistently more at risk of developing and dying from CAd than women, and the gender-specific effects of sex hormones are implicated in this inequality. This ＇Perspectives＇ article reviews the current evidence regarding the cardiovascular effects of testosterone in men including an examination of the age-related decline in testosterone, the relationship between testosterone levels and coronary disease, coronary risk factors and mortality. We also review the vaso-active effects of testosterone, and discuss how these have been used in men with heart failure and angina. We discuss the ＇cause＇ versus ＇effect＇ controversy, regarding low testosterone levels in men with coronary heart disease, as well as concerns over the use of testosterone replacement therapy in middle aged and elderly men. The article concludes with a discussion regarding the future direction for work in this interesting area, including the relative merits of screening for, and treating hypogonadism with testosterone replacement therapy in men with heart disease.

关键词： atherosclerosis chronic heart failure ischaemic heart disease replacement therapy testosterone

CRACK PROPAGATION IN STRUCTURES SUBJECTEd TO PERIOdIC EXCITATION

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Acta Mechanica Solida Sinica 2007年第3期20卷 236-246页

作者： Zhang Yin Murphy kevin d. State Key Laboratory of Nonlinear Mechanics （LNM） Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China department of Mechanical Engineering University of Connecticut CT 06269-3139 USA

In the present paper, asimple mechanical modelis developed to predict thedynamic response of a cracked structure subjected to periodic excitation, which has been used to identify the physical mechanisms in leading the growth or arrest of cracking. The structure under consideration consists of a beam with a crack along the axis, and thus, the crack may open in Mode I and in the axial direction propagate when the beam vibrates. In this paper, the system is modeled as a cantilever beam lying on a partial elastic foundation, where the portion of the beam on the foundation represents the intact portion of the beam. Modal analysis is employed to obtain a closed form solution for the structural response. Crack propagation is studied by allowing the elastic foundation to shorten （mimicking crack growth） if a displacement criterion, based on the material toughness, is met. As the crack propagates, the structural model is updated using the new foundation length and the response continues. From this work, two mechanisms for crack arrest are identified. It is also shown that the crack propagation is strongly influenced by the transient response of the structure.

关键词： crack propagation/arrest elastic foundation modal analysis vibration natural frequency

Nonlinear dynamic response of beam and its application in nanomechanical resonator

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Acta Mechanica Sinica 2012年第1期28卷 190-200页

作者： Yin Zhang Yun Liu kevin d.Murphy State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of Sciences100190 BeijingChina Faculty of Information and Automation Kunming University of Science and Technology650051 KunmingChina department of Mechanical Engineering The University of ConnecticutStorrsCT 06269USA

Nonlinear dynamic response of nanomechanical resonator is of very important characteristics in its application. Two categories of the tension-dominant and curvaturedominant nonlinearities are analyzed. The dynamic nonlinearity of four beam structures of nanomechanical resonator is quantitatively studied via a dimensional analysis approach. The dimensional analysis shows that for the nanomechanical resonator of tension-dominant nonlinearity, its dynamic nonlinearity decreases monotonically with increasing axial loading and increases monotonically with the increasing aspect ratio of length to thickness; the dynamic nonlinearity can only result in the hardening effects. However, for the nanomechanical resonator of the curvature-dominant nonlinearity, its dynamic nonlinearity is only dependent on axial loading. Compared with the tension-dominant nonlinearity, the curvature-dominant nonlinearity increases monotonically with increasing axial loading; its dynamic nonlinearity

关键词： Resonator. dynamic response. dynamic nonlinearity - dimensional analysis

Epitypification:should we epitypify?

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2008年第10期9卷 842-846页

作者： kevin d. HYdE Ying ZHANG International Fungal Research and development Centre the Research Institute of Resource Insects Chinese Academy of Forestry Kunming 650224 China Fungal Research Group School of Science Mae Fah Luang University Tasud Muang Chiang Rai 5 7100 Thailand Centre for Research in Fungal diversity School of Biological Sciences University of Hong Kong Hong Kong China

Epitypification can solve many taxonomic problems and stabilize the understanding of species, genera, families or orders. The aim of this paper is to illustrate how to epitypify. A few examples where taxa have been epitypified are considered and the benefits and disadvantages of epitypification are discussed. We also outline some examples of taxa which need to be epitypifled with reasons.

关键词： Colletotrichum GenBank Molecular phylogeny Taxonomy Typification

Rapid Evaluation and Response to Impacts on Critical End-Use Loads Following Natural Hazard-driven Power Outages:A Modular and Responsive Geospatial Technology

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International Journal of disaster Risk Science 2022年第3期13卷 415-434页

作者： Patrick d.Royer Wei du kevin Schneider Energy and Environment Pacific Northwest National LaboratoryRichlandWA99352USA

The disparate nature of data for electric power utilities complicates the emergency recovery and response *** reduced efficiency of response to natural hazards and disasters can extend the time that electrical service is not available for critical end-use loads,and in extreme events,leave the public without power for extended *** article presents a methodology for the development of a semantic data model for power systems and the integration of electrical grid topology,population,and electric distribution line reliability indices into a unified,cloud-based,serverless framework that supports power system operations in response to extreme *** iterative and pragmatic approach to working with large and disparate datasets of different formats and types resulted in improved application runtime and efficiency,which is important to consider in real time decision-making processes during hurricanes and similar catastrophic *** technology was developed initially for Puerto Rico,following extreme hurricane and earthquake events in 2017 and 2020,but is applicable to utilities around the *** the highly abstract and modular design approach,this technology is equally applicable to any geographic region and similar natural hazard *** addition to a review of the requirements,development,and deployment of this framework,technical aspects related to application performance and response time are highlighted.

关键词： Electrical grid Hurricane response Puerto Rico Resilience and geospatial technology Software applications

Sequential light programs shape kale (Brassica napus) sproutappearance and alter metabolic and nutrient content

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Horticulture Research 2014年第1期1卷 244-256页

作者： Sofia d Carvalho kevin M Folta Horticultural Sciences department University of FloridaGainesvilleFLUSA Plant Molecular and Cellular Biology Program University of FloridaGainesvilleFLUSA Plant Innovation Program University of FloridaGainesvilleFLUSA

different light wavelengths have specific effects on plant growth and ***-bandwidth light-emitting diode(LEd)lighting may be used to directionally manipulate size,color and metabolites in high-value fruits and *** this report,Red Russian kale(Brassica napus)seedlings were grown under specific light conditions and analyzed for photomorphogenic responses,pigment accumulation and nutraceutical *** results showed that this genotype responds predictably to darkness,blue and red light,with suppression of hypocotyl elongation,development of pigments and changes in specific ***,these seedlings were relatively hypersensitive to far-red light,leading to uncharacteristically short hypocotyls and high pigment accumulation,even after growth under very low fluence rates(,1 mmol m^(-2) s^(-1)).General antioxidant levels and aliphatic glucosinolates are elevated by far-red light *** treatments of darkness,blue light,red light and far-red light were applied throughout sprout development to alter final product *** results indicate that sequential treatment with narrow-bandwidth light may be used to affect key economically important traits in high-value crops.

关键词： treatment content narrow