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Damper placement for seismic control of super-long-span suspension bridges based on the first-order optimization method

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Science China(Technological Sciences) 2010年第7期53卷 2008-2014页

作者： Billie f SPENCER Department of Civil and Environmental Engineering University of Illinois at Urbana-Champaign

To ensure the anti-earthquake performances of super-long-span suspension bridges, effective devices should be employed to control the seismic response of key sections. In this paper, four kinds of assessment functions for seismic response control effect are formulated based on the mechanism of seismic response control with dampers and the seismic response characteristics of long-span suspension bridges. A new optimal placement method of dampers using penalty function and first-order optimization theory is then proposed. Runyang suspension bridge (RSB) with a main span of 1490 m is then taken as an example. After seismic response time-history analyses on RSB using different placements of dampers, the analysis results are optimized by employing the optimal placement method and the optimal placements of dampers with the four assessment functions are then achieved respectively. Comparison of the four optimal control effects show that different assessment functions can lead to different optimal placements when the number of dampers is certain, but all placements of dampers can reduce the seismic response of RSB significantly. The selection of assessment functions and damper optimal placement should be determined by the structural characteristics and by what is considered in the structures. Results also show that the first-order optimization is an effective method on determining the optimal placement of dampers.

关键词： suspension bridge seismic control damper placement control effect assessment first-order optimization method

Effect of thermal conductivity on heat transfer for a power-law non-Newtonian fluid over a continuous stretched surface with various injection parameters

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Applied Mathematics and Mechanics(English Edition) 2010年第8期31卷 963-968页

作者： f.A.SALAMA Department of Mathematics Faculty of Science Suez Canal University

The two-dimensional non-Newtonian steady flow on a power-law stretched surface with suction or injection is studied. Thermal conductivity is assumed to vary as a linear function of temperature. The transformed governing equations in the present study are solved numerically using the Runge-Kutta method. Through a comparison, results for a special case of the problem show excellent agreement with those in a previous work. Two cases are considered, one corresponding to a cooled surface temperature and the other to a uniform surface temperature. Numerical results show that the thermal conductivity variation parameter, the injection parameter, and the power-law index have significant influences on the temperature profiles and the Nusselt number.

关键词： non-Newtonian fluid thermal conductivity power-law fluid heat transfer

Serum testosterone levels and excessive erythrocytosis during the process of adaptation to high altitudes

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Asian Journal of Andrology 2013年第3期15卷 368-374页

作者： Gustavo f Gonzales High Altitude Research Institute and Department of Biological and Physiological Sciences Faculty of Sciences and Philosophy Universidad Peruana Cayetano Heredia Lima 31 Peru

Populations living at high altitudes （HAs）, particularly in the Peruvian Andes, are characterized by a mixture of subjects with erythrocytosis （16 g dl-1〈haemoglobin （Hb）≤21 gdl-1） and others with excessive erythrocytosis （EE）（Hb〉21 g dl-1）. Elevated haemoglobin values （EE） are associated with chronic mountain sickness, a condition reflecting the lack of adaptation to HA. According to current data, native men from regions of HA are not adequately adapted to live at such altitudes if they have elevated serum testosterone levels. This seems to be due to an increased conversion of dehydroepiandrosterone sulphate （DH EAS） to testosterone. Men with erythrocytosis at HAs show higher serum androstenedione levels and a lower testosterone/androstenedione ratio than men with EE, suggesting reduced 17beta-hydroxysteroid dehydrogenase （17beta-HSD） activity. Lower 17beta-HSD activity via A4-steroid production in men with erythrocytosis at HA may protect against elevated serum testosterone levels, thus preventing EE. The higher conversion of DHEAS to testosterone in subjects with EE indicates increased 17beta-HSD activity via the A5-pathway. Currently, there are various situations in which people live （human biodiversity） with low or high haemoglobin levels at HA. Antiquity could be an important adaptation component for life at HA, and testosterone seems to participate in this process.

关键词： chronic mountain sickness DHEA haemoglobin high altitudes men oestradiol women

Modelling ballistic impact on military helmets:The relevance of projectile plasticity

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Defence Technology（防务技术） 2021年第5期17卷 1699-1711页

作者： A.Caçoilo R.Mourao f.Teixeira-Dias A.Azevedo f.Coghe R.A.f.Valente School of Engineering The University of EdinburghEdinburghEH93FGUK Dept.Weapon Systems and Ballistics Royal Military AcademyBrusselsBelgium Centre for Mechanical Technology and Automation Department of Mechanical EngineeringUniversity of AveiroPortugal

The need to develop armour systems to protect against attacks from various sources is increasingly a matter of personal,social and national *** develop innovative armour systems it is necessary to monitor developments being made on the type,technology and performance of the threats(weapons,projectiles,explosives,etc.) Specifically,the use of high protection level helmets on the battlefield is *** development of evaluation methods that can predict injuries and trauma is therefore of major ***,the risk of injuries or trauma that can arise from induced accelerations is an additional *** develop new materials and layouts for helmets it is necessary to study the effects caused by ballistic impacts in the human head on various *** use of numerical simulation is a fundamental tool in this *** work here presented focuses on the use of numerical simulation(finite elements analysis) to predict the consequences of bullet impacts on military helmets on human *** main objectives are to assess the level and probability of head trauma using the Head Injury Criterion,caused by the impact of a 9 mm NATO projectile on a PASGT helmet and to quantify the relevance of projectile plasticity on the whole modelling *** accelerations derived from the impact phenomenon and the deformations caused on the helmet are evaluated using fully three-dimensional models of the helmet,head,neck and *** studies are done at impact angles ranging from 0 to 75°.Results are presented and discussed in terms of HIC and probability of acceleration induced trauma *** comparison analyses are done using a rigid and a deformable projectile and it is observed that plastic deformation of the projectile is a significant energy dissipation mechanism in the whole impact process.

关键词： Ballistic impact Helmet impact Plasticity finite element analysis Injury Trauma HIC

The theoretical study of the efficiency of diffusion deposition of nanoaerosols in the extended range of the Peclet numbers

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Particuology 2023年第6期77卷 47-55页

作者： R.f.Mardanov S.K.Zaripov V.f.Sharafutdinov N.I.Lobachevskii Institute of Mathematics and Mechanics Kazan(Volga Region)Federal UniversityKremlevskaya ul.18KazanTatarstan420008Russia

The efficiencies of the diffusion deposition of nanoaerosols for a single fiber for the models of aerosol filter and wire mesh screen are studied numerically in the extended range of the Peclet number *** rectangular periodic cell model for fluid flow and convective-diffusive transport of small aerosol particles is *** of the previous theoretical and experimental studies of single fiber diffusion deposition efficiency were for the case of Pe>*** array with uniform square or chess grid of fibers and of a row of circular cylindrical fibers are considered as the filter and wire mesh screen *** flow and particles transport equations are solved numerically using the Boundary Element *** obtained numerical data are used to derive the approximate formulas for the deposition efficiency in the entire range of the Peclet number for the various porosities of the filter medium or distances between fibers in a wire mesh *** derived dependencies take into account nonlinearity of the deposition efficiency at the low Peclet *** obtained analytical dependencies compare well with the numerical and experimental data.

关键词： Arrayof fibers Row of fibers Periodic cell model Convection-diffusion equation Single fiber efficiency

Charge susceptibilities of armchair graphene nanoribbon in the presence of magnetic field

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Chinese Physics B 2016年第9期25卷 511-517页

作者： H Rezania f Azizi Department of Physics Razi University

We present the behaviors of both dynamical and static charge susceptibilities of undoped armchair graphene nanoribbon using the Green＇s function approach in the context of tight binding model ***,the effects of magnetic field on the the plasmon modes of armchair graphene nanoribbon are investigated via calculating the correlation function of charge density *** results show that the increase of magnetic field makes the high-frequency plasmon mode for both metallic and insulating cases *** also show that low-frequency plasmon mode for metallic nanoribbon appears due to increase of magnetic ***,the number of collective excitation modes increases with ribbon width at zero magnetic ***,the temperature dependence of the static charge structure factor of armchair graphene nanoribbon is *** effects of both magnetic field and ribbon width on the static charge structure factor are discussed in detail.

关键词： armchair graphene nanoribbon Green's function

A Label-free Detection of Biomolecules Using Micromechanical Biosensors

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Chinese Physics Letters 2013年第6期30卷 228-231页

作者： Meisam Omidi M.A.Malakoutian Mohammadmehdi Choolaei f.Oroojalian f.Haghiralsadat f.Yazdian faculty of New Science and Technology University of TehranTehranIran Department of Electrical and Computer Engineering University of TehranTehranIran Department of Chemical Engineering South Tehran BranchIslamic Azad UniversityTehranIran

A Microcantilevers resonator is used to detect a protein biomarker called prostate specific antigen(PSA),which is associated with prostate *** concentrations of PSA in a buffer solution are detected as a function of deflection of the *** this purpose,we use a surface micromachined,antibody-coated polycrystalline silicon micromechanical cantilever *** have mass sensitivities of the order of 10–17 g/Hz,which result from their small *** matter allows them to detect an immobilized antibody monolayer corresponding to a mass of about 70 *** these devices,concentrations as low as 150 fg/mL,or 4.5 fM,could be detected from the realistic samples.

关键词： cantilever resonator polycrystalline

Trajectory control of pneumatic servo table with air bearing

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Trajectory control of pneumatic servo table with air bearing

Anosov and expanding attractors

2011 International Conference on fluid Power and Mechatronics

作者： Kenji kawashima Toshiharu Kagawa Toshinori fujita Mechano-Micro Engineering Department Tokyo Institute of Technology Nagatsuta-cho Midori-kuYokohamaKanagawaJapan Tokyo Denki University Kanda-nishiki-cho Chiyoda-kuTokyo 101-8457Japan

In this paper,the trajectory control design of the pneumatic servo table considering the dynamics of pipelines and servo valve is *** table is mainly composed by a pneumatic actuator,the high-performance pneumatic servo valve and *** pneumatic actuator utilizes a pneumatic cylinder with air *** servo valve,with high dynamics up to 300Hz,is connected with the pneumatic actuator by *** whole system is pneumatically driven,it has advantages like low heat generation and non-magnetic,which are suitable for precise positioning.A linear model considering the dynamics of pipelines and the servo valve is designed to simulate the *** with experimental results,it is found that with 7th order linear control model,the discrepancy between experimental and simulation results became much smaller than the 3rd order model was ***,a low dimensional model is necessary for practical *** there are two poles which are much further from imaginary axis compared with other five poles in the pole loci of the 7th order model,the model’s order can be reduced into *** comparing simulation with experimental results,we found that the 5th order model can also match with the real system *** on this result,a 5th order feed forward has been *** a curve which can derivate by five times is inputted,the experimental results show that the maximum trajectory has been minimized by 20μm.

关键词： Pneumatics Trajectory control Linear model Pneumatic servo table

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Science China Mathematics 2020年第9期63卷 1929-1934页

作者： Robert f.Williams Department of Mathematics University of Texas at AustinAustinTX 78705USA Institute for Advanced Study PrincetonNJ 08540USA

An earlier conjecture is settled with an immersion of a 2-dimensional branched *** obstructions in linear algebra and tiling theory are studied rst.

关键词： Anosov expanding attractor Cantor set ber bundle