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Energy principle of ferroelectric ceramics and single domain mechanical model

Acta Mechanica Sinica 2007年第5期23卷 531-543页

作者： t.C.Wang LNM Institute of MechanicsChinese Academy of SciencesBeijing 100080China

Many physical experiments have shown that the domain switching in a ferroelectric material is a complicated evolution process of the domain wall with the variation of stress and electric field. According to this mechanism, the volume fraction of the domain switching is introduced in the constitutive law of ferroelectric ceramic and used to study the nonlinear constitutive behavior of ferroelectric body in this paper. the principle of stationary total energy is put forward in which the basic unknown quantities are the displacement ui, electric displacement Di and volume fraction pI of the domain switching for the variant I. Mechanical field equation and a new domain switching criterion are obtained from the principle of stationary total energy. the domain switching criterion proposed in this paper is an expansion and development of the energy criterion. On the basis of the domain switching criterion, a set of linear algebraic equations for the volume fraction PI of domain switching is obtained, in which the coefficients of the linear algebraic equations only contain the unknown strain and electric fields. then a single domain mechanical model is proposed in this paper. the poled ferroelectric specimen is considered as a transversely isotropic single domain. By using the partial experimental results, the hardening relation between the driving force of domain switching and the volume fraction of domain switching can be calibrated. then the electromechanical response can be calculated on the basis of the calibrated hardening relation. the results involve the electric butterfly shaped curves of axial strain versus axial electric field, the hysteresis loops of electric displacement versus electric filed and the evo- lution process of the domain switching in the ferroelectric specimens under uniaxial coupled stress and electric field loading. the present theoretic prediction agrees reasonably with the experimental results given by Lynch.

关键词： Ferroelectric ceramic Domain switching the volume fraction of domain switching Single domain mechanical model

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Recent advances in the production of controllable multiple emulsions using microfabricated devices

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Particuology 2016年第1期14卷 1-17页

作者： Goran t. Vladisavljevic Chemical Engineering Department Loughborough University Loughborough LE11 3TU Leicestershire United Kingdom

this review focuses on recent developments in the fabrication of multiple emulsions in micro-scale systems such as membranes, microchannel array, and microfluidic emulsification devices. Membrane and microchannel emulsification offer great potential to manufacture multiple emulsions with uniform drop sizes and high encapsulation efficiency of encapsulated active materials. Meanwhile, microfluidic devices enable an unprecedented level of control over the number, size, and type of internal droplets at each hierarchical level but suffer from low production scale. Microfluidic methods can be used to generate high-order multiple emulsions （triple, quadruple, and quintuple）, non-spherical （discoidal and rod-like） drops, and asymmetric drops such as Janus and ternary drops with two or three distinct surface regions. Multiple emulsion droplets generated in microfabricated devices can be used as templates for vesicles like polymersomes, liposomes, and colloidosomes with multiple inner compartments for simultaneous encaosulation and release of incomoatible active materials or reactants.

关键词： Membrane emulsification Microchannel emulsification Droplet microfluidics Microencapsulation Multiple emulsionsJanus droplets

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Development of Architectures for Internet telerobotics Systems

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Journal of Bionic Engineering 2007年第4期4卷 291-297页

作者： Riyanto t. Bambang School of Electrical Engineering and Informatics Bandung Institute of Technology Bandung 40132 Indonesia

this paper presents our experience in developing and implementing Internet telerobotics system. Internet telerobotics system refers to a robot system controlled and monitored remotely through the Internet. A robot manipulator with five degrees of freedom, called Mentor, is employed. Client-server architecture is chosen as a platform for our Internet telerobotics system. three generations of telerobotics systems have evolved in this research. the first generation was based on CGI and two tiered architectures, where a client presents a Graphical User Interface to the user, and utilizes the user＇s data entry and actions to perform requests to robot server running on a different machine. the second generation was developed using Java. We also employ Java 3D for creating and manipulating 3D geometry of manipulator links, and for constructing the structures used in rendering that geometry, resulting in 3D robot movement simulation presented to the users （clients） through their web browser. Recent development in our Internet telerobotics includes object recognition through image captured by a camera, which poses challenging problem, giving the undeterministic latency of the Internet. the third generation is centered around the use of CORBA for development platform of distributed internet telerobotics system, aimed at distributing task of telerobotics system.

关键词： telerobotics manipulator Internet CGI Java Java 3D CORBA

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Line of sight waypoint guidance for a container ship based on frequency domain identification of Nomoto model of vessel

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Journal of Central South University 2016年第8期23卷 1944-1953页

作者： M.t.Ghorbani Instituto Superior tecnico Torre Norte-8.17 1049-001 Lisboa Portugal

CIFER software is used to identify steering and roll dynamics of a container ship. In this software, advanced features such as the Chirp-Z transform(CZt) and composite window optimization are applied to the time history of steering and roll dynamics to extract high quality frequency responses. From the extracted frequency responses, two linear transfer functions of Nomoto model are fitted for yaw and roll dynamics of the vessel. Based on the identified Nomoto model, a PID heading controller and a Kalman filter observer are constructed. the simulation results of heading controller for line of sight(LOS) waypoint guidance show excellent tracking of pilot inputs in the presence of wave induced motions and forces.

关键词： container ship Nomoto model Kalman filter frequency domain identification CIFER software

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Navigation sensors and systems in GNSS degraded and denied environments

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Chinese Journal of Aeronautics 2015年第1期28卷 1-10页

作者： George t.Schmidt IEEE Aerospace and Electronic Systems Society

Position, velocity, and timing（PVt） signals from the Global Positioning System（GPS）are used throughout the world but the availability and reliability of these signals in all environments has become a subject of concern for both civilian and military applications. this presentation summarizes recent advances in navigation sensor technology, including GPS, inertial, and other navigation aids that address these concerns. Also addressed are developments in sensor integration technology with several examples described, including the Bluefin-21 system mechanization.

关键词： navigation inertial GNSS environments receiver degraded military addressed presentation advances

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Combining innovative science and policy to improve air quality in cities with refining and chemicals manufacturing： the case study of Houston, texas, USA

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Frontiers of Chemical Science and Engineering 2017年第3期11卷 293-304页

作者： David t. Allen University of texas Austin Department of Chemical Engineering and Center for Energy and Environmental Resources Austin TX 78759 USA

In Houston, a combination of urban emissions from a city of 4 million people, coupled with emissions from extensive petroleum refining and chemical manufacturing, leads to conditions for photochemistry that are unique in the United States, and historically, the city had experienced some of the highest ozone concentrations recorded in the United States. Large air quality field studies （the texas Air Quality Studies or texAQS I and II） were conducted to determine root causes of the high ozone concentrations. Hundreds of air quality investigators, from around the world, deployed instruments on aircraft, on ships, and at fixed ground sites to make extensive air quality measurements; detailed photochemical modeling was used to interpret and assess the implications of the measurements. the texas Air Quality Studies revealed that both continuous and episodic emissions of light alkenes, which came to be called highly reactive volatile organic compounds, played a critical role in the formation of ozone and other photochemical oxidants in the region. Under- standing and quantifying the role of these emissions in regional air quality required innovations in characterizing emissions and in photochemical modeling. Reducing emissions required innovative policy approaches. these coupled scientific and policy innovations are described, and the result, substantially cleaner air for Houston, is documented. the lessons learned from the Houston air quality experience are relevant to cities with similar population and industrial profiles around the world.

关键词： ozone air quality highly reactive volatile organic compounds Houston

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trophic attributes of the mudskipper, Periophthalmus barbarus (Gobiidae: Oxudercinae) in the mangrove swamps of Imo River Estuary, Nigeria

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Journal of Environmental Sciences 2002年第4期14卷 508-517页

作者： Mfon t.UDO Department of Fisheries and Aquaculture Faculty of AgricultureUniversity of Uyo

Aspects of the trophic attributes of the mudskipper, Periophthalmus barbarus occurring in the mangrove swamps of Imo River Estuary, Nigeria, were investigated during a 12 month period (April, 1992\_March, 1993). Feeding intensity increased with size, it was higher in the dry season(November\_April) than in the wet season(May\_October), monthly changes in the indices of feeding intensity were significantly correlated. Major food objects comprised detritus and benthic algae; crustaceans, insects, macrophyte matter and sand grains were minor food objects while fish, molluscs, Chilopoda, nematodes and fungi were unconsciously devoured objects. Diet varied seasonally; algae and sesarmid crabs were generally more in the dry season than during the rains whereas FPOM and fish increased in the wet over dry season. the mudskipper display a high degree of euryphagy and can be considered as a generalist and an omnivore. the lower trophic status of P. barbarus qualifies it as a good aquaculture candidate. Food richness was higher in big sized class(BSC) than small sized class(SSC). Size based and seasonal variations were not apparent in food richness. Diet breadth was higher in the BSC than the SSC, there was dry season increase in diet breadth.

关键词： Periophthalmus barbarus indices of feeding intensity diet composition mangrove swamp Imo River Estuary Nigeria

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Hawking radiation of stationary and non-stationary Kerr–de Sitter black holes

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Chinese Physics B 2015年第7期24卷 141-148页

作者： t.Ibungochouba Singh Department of Mathematics Manipur University

Hawking radiation of the stationary Kerr–de Sitter black hole is investigated using the relativistic Hamilton–Jacobi method. Meanwhile, extending this work to a non-stationary black hole using Dirac equations and generalized tortoise coordinate transformation, we derived the locations, the temperature of the thermal radiation as well as the maximum energy of the non-thermal radiation. It is found that the surface gravity and the Hawking temperature depend on both time and different angles. An extra coupling effect is obtained in the thermal radiation spectrum of Dirac particles which is absent from thermal radiation of scalar particles. Further, the chemical potential derived from the thermal radiation spectrum of scalar particle has been found to be equal to the highest energy of the negative energy state of the scalar particle in the non-thermal radiation for the Kerr–de Sitter black hole. It is also shown that for stationary black hole space time, these two different methods give the same Hawking radiation temperature.

关键词： Hamilton–Jacobi method non-stationary Kerr–de Sitter black hole Hawking radiation general-ized tortoise coordinate transformatio

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theory and Modeling of Phase transformations under Stress in Steel

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材料热处理学报 2004年第5期25卷 1-7页

作者： t.Y. Hsu School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200030 China

thermodynamic prediction of the increment of the formation temperature of proeutectoid ferrite by appliedstress is nearly consistent with the wxperfimental *** models for ferrite,pearlite and bainite transformations can be shown as modified Johnson-Mehl-Avrami equation in which parameter b() varies with the level of applied *** effects of tensile and compressive stresses on enhancement of the ferrite/pearlite and bainite transformations are discussed,the necessity and approach of modification of additivity hypothesis are introduced and the results from modified equation in which some parameters are obtained by rfegression of two experimental results or taken from ttt and CCt diagrams of a cerftain steel are superior than that from Scheil’s *** calculation of Ms and nucleation kinetics equations of martensitic transformation under stress are *** of phase trasformations under stress in ferrous alloys is briefly

关键词：钢相位转换受力状态热力学动力学成核现象相加性假设铁合金

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Supergravity-induced interactions on thick branes

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Chinese Physics B 2014年第4期23卷 135-146页

作者： Nejat t.Yilmaz Department of Electrical and Electronics Engineering Yassar UniversitySelsuk Yassar Kampüsü niversite CaddesiNo:35-37 AgaliYol35100 Bornova zmir Turkey

the gravity coupling of the symmetric space sigma model is studied in the solvable Lie algebra parametrization. the corresponding Einstein equations are derived and the energy-momentum tensor is calculated. the results are used to derive the dynamical equations of the warped five-dimensional （5D） geometry for localized bulk scalar interactions in the framework of thick brane world models. the Einstein and scalar field equations are derived for flat brane geometry in the context of minimal and non-minimal gravity-bulk scalar couplings.

关键词： supergravity branes 5D warped geometry symmetric spaces

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