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Topology optimization of piezoelectric bi-material actuators with velocity feedback control

Frontiers of Mechanical Engineering 2019年第2期14卷 190-200页

作者： Mariana MORETTI Emilio c.n.SILVA School of Engineering University of Sao PauloSao PauloSP 05508-030Brazil

In recent years,the new technologies and discoveries on manufacturing materials have encouraged researchers to investigate the appearance of material properties that are not naturally *** featuring a specific stiffness,or structures that combine non-structural and stmctural functions are applied in the aerospace,electronics and medical industry ***,structures designed for dynamic actuation with reduced vibration response are the focus of this *** bi-material and multifunctional concepts are considered for the design of a controlled piezoelectric actuator with vibration suppression by means of the topology optimization method(TOM).The bi-material piezoelectric actuator(BPEA)has its metallic host layer designed by the TOM,which defines the structural function,and the electric function is given by two piezo-ceramic layers that act as a sensor and an actuator coupled with a constant gain active velocity feedback control(AVFc).The AVFc,provided by the piezoelectric layers,affects the structural damping of the system through the velocity state variables readings in time *** dynamic equation analyzed throughout the optimization procedure is fully elaborated and *** dynamic response for the rectangular fbur-noded finite element analysis is obtained by the newmark's time-integration method,which is applied to the physical and the adjoint systems,given that the adjoint formulation is needed for the sensitivity analysis.A gradient-based optimization method is applied to minimize the displacement energy output measured at a predefined degree-of-freedom of the BPEA when a transient mechanical load is *** are obtained for different control gain values to evaluate their influence on the final topology.

关键词： topology optimization method bi-material piezoactuator active velocity feedback control timedomain transient analysis host structure design vibration suppression

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characteristics of a Gan-based Gunn diode for THz signal generation

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Journal of Semiconductors 2012年第8期33卷 37-43页

作者： R K Parida n c Agrawala G n Dash A K Panda ITER Siksha‘O'Anusandhan University Rengali college Sambalpur University national Institute of Science&Technology

A generalized large-signal computer simulation program for a Gunn oscillator has been developed. The properties of a Gunn diode oscillator based on the widely explored Gan, are investigated using the developed program. The results show some interesting properties in Gan Gunn diodes which are not seen in GaAs and InP diodes. An output power of 1400 kW/cm^2 is achieved from the Gan Gunn diode, as compared to 4.9 kW/cm^2 from a GaAs diode.

关键词： Gunn devices semiconductor diodes semiconductor materials power Gan

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control strategy for seamless transition from islanded to interconnected operation mode of microgrids

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Journal of Modern Power Systems and clean Energy 2017年第2期5卷 169-176页

作者： c.n.PAPADIMITRIOU V.A.KLEFTAKIS n.D.HATZIARGYRIOU Department of Electrical and computer Engineering National Technical University of Athens(NTUA)AthensGreece

Microgrids can operate either interconnected to the utility grid or disconnected forming an island. The transition between these modes can cause transient overcurrents or power oscillations jeopardizing the equipment safety or the system stability. This paper proposes a local multi agent control method for a seamless transfer between the islanded and interconnected modes of operation with agents implemented into the microgrid central switch(McS) and into the microsources inverters. The McS agent supervises the grid status and controls the switch for the transition of the microgrid through the different operation modes, while it communicates locally with the inverter agents of the microsources. The inverter agents undertake the synchronization process in case of reconnecting and change the inverter control mode depending on the grid status. Simulation and experimental results are presented to show the performance and feasibility of the proposed strategy.

关键词： Microgrid Islanding Reconnection Agents Synchronization control hardware-in-the-loop(cHIL)

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THE STRESS-EnERGY TEnSOR AnD POHOZAEV'S IDEnTITY FOR SYSTEMS

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Acta Mathematica Scientia 2012年第1期32卷 433-439页

作者： n.D.Alikakos A.c.Faliagas Department of Mathematics University of Athens

Utilizing stress-energy tensors which allow for a divergence-free formulation, we establish Pohozaev＇s identity for certain classes of quasilinear systems with variational structure.

关键词： calculus of variations stress-energy tensor p-Lapacian minimal surface

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Detection of Low Sugar concentration Solution Using Frequency Selective Surface (FSS)

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computers, Materials & continua 2022年第5期71卷 2869-2882页

作者： n.S.Ishak F.c.Seman n.Zainal n.A.Awang Faculty of Electrical and Electronics Engineering Universiti Tun Hussein Onn MalaysiaParit RajaBatu Pahat86400Malaysia Research center for Applied Electromagnetics(EMcenter) The Institute of Integrated EngineeringUniversiti Tun Hussein Onn MalaysiaParit RajaBatu Pahat86400Malaysia Microelectronic and nanotechnology-Shamsuddin Research centre(MinT-SRc) The Institute of Integrated EngineeringUniversiti Tun Hussein OnnParit RajaBatu Pahat86400Malaysia Photonics Devices and Sensor Research(PDSR) Faculty of Applied Science and Technology(FAST)Universiti Tun Hussein Onn Malaysia(Pagoh Campus)JorakBukit Pasir84500Malaysia

Sugar is important in daily food intake since it is used as food preservative and ***,is important to analyze the influence of sugar on the spectroscopic properties of the *** spectroscopy is proven to be useful and an efficient method for sugar detection as well as for future food quality ***,the lack of detection sensitivity in Terahertz Spectroscopy has prevented it from being used in a widespread spectroscopic analysis *** this paper,Frequency Selective Surface(FSS)using the Terahertz Spectroscopy Time Domain Spectrum(THz-TDS)which operates at terahertz frequency range has been demonstrated for application of sugar *** FSS is designed with a circle slot structure and has been optimized in line with the molecular resonance of glucose and fructose at different level concentration at 1.98 THz and 1.80 THz,*** magnitude of glucose and sucrose is inversely proportional with the level of sugar *** realization of the FSS structure is using electron beam lithography and wet etching *** show that the FSS performance for glucose and sucrose reveal fair shifts in measured transmission magnitude from its original in cST by approximately 30%.The use of fabricated FSS with circle structure indicates that the concentration can be improved averagely at 25%for glucose and 13%for ***,it shows that the FSS circle structure combined with THz-TDS has the potential to become an alternative method for food sensing technology in the future.

关键词： THz sensing FSS circle structure sugar concentration

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Experimental study of the effect of wear parameters on the wear behavior of A356 alloy/cow horn particulate composites

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Defence Technology（防务技术） 2018年第1期14卷 77-82页

作者： B.Q.Ochieze c.c.nwobi-Okoye P.n.Atamuo Lafarge Africa Plc Mfamosing Plant Department of Mechanical Engineering Chukwuemeka Odumegwu Ojukwu University

Experimental study of the effect of wear parameters on the wear behaviour of A356 alloy reinforced with cow horn particles(cHp) produced by spark plasma sintering was investigated. Experiments were conducted based on the plan of experiments generated through Taguchi's(L9) technique. Tribometer was used for the wear test and Scanning electron microscope was used to analyse the worn scar of the samples. The results shows that, A356 alloy reinforced with cHp exhibited better dry sliding wear resistance than the unreinforced alloy. Wear rate decreased as the amount of cHp reinforcement increased in the matrix. It was found that, the optimum level of the factors with minimized the wear loss were obtained at: wt%cHp(20%), applied load(10 n), sliding velocity(3 m/s) and sliding distance(2000 m). It can be seen that the wear track of the sample are(D ? 0.81 and L = 42.85 mm) and(D ? 0.54 and L= 27.03 mm) for A356 alloy and composites at optimum condition respectively. The results showed that the addition of cow horn particles as reinforcing materials in A356 alloy composites increased the wear resistance of the composites greatly.

关键词： A356alloy cow horn particles Microstructure Analysis of variance and wear behaviour

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Interplay of parallel electric field and trapped electrons in kappa-Maxwellian auroral plasma for EMEc instability

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communications in Theoretical Physics 2021年第1期73卷 78-86页

作者： M nazeer M n S Qureshi c Shen Department of Physics GC UniversityLahore(54000)Pakistan Shenzhen Graduate School HIT CampusUniversity Town of ShenzhenShenzhen 518055China

In this paper,propagation characteristics of electromagnetic electron cyclotron(EMEc)waves based on kappa-Maxwellian distribution have been investigated to invoke the interplay of the electric field parallel to the Earth’s magnetic field and auroral trapped *** dispersion relation for EMEc waves in kappa-Maxwellian distributed plasma has been derived using the contribution of the parallel electric field and trapped electron *** results show that the presence of the electric field has a stimulating effect on growth rate,which is more pronounced at low values of wave *** is also observed that as the threshold value of trapped electron speed is surpassed,it dominates the effect of the parallel electric field and EMEc instability is enhanced *** electric field acts as another source of free energy,and growth can be obtained even in the absence of trapped electron drift speed and for very small values of temperature *** the present study reveals the interplay of the parallel electric field and trapped electron speed on the excitation of EMEc waves in the auroral region.

关键词： EMEc waves kappa-Maxwellian distribution trapped electrons parallel electric field in aurora

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A new Method of Synthesis of Azo Schiff Base Ligands with Azo and Azomethine Donors： Synthesis of n-4-Methoxybenzylidene-2-（3-hydroxyphenylazo）-5-hydroxyaniline and Its nickel（Ⅱ） complex

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chinese Journal of chemistry 2007年第6期25卷 869-871页

作者： OFORKA, n. c. MKPEnIE, V. n. Department of Pure and Industrial chemistry University of Port Harcourt P. M. B. 5323 Port Harcourt Nigeria

A new method for the synthesis of azo Schiff an base ligand in which the azo and azomethine groups are coordination sites was developed through a Schiff base precursor. The precursor, n-4-methoxybenzylidene-3-hydroxyphenylamine （SB） derived from 3-aminophenol was regioselectively coupled with a diazonium ion para to the hydroxyl group of the amine component of the Schiff base. The para selectivity was controlled by the directing effect of the hydroxyl group. The ligand and its nickel（Ⅱ） complex were characterized by elemental analyses, IR and UV-Vis spectroscopy. The analytical and spectral data supported the mononuclear formulation of the complex with metal to ligand ratio （M ： L = 1 ： 2） and suggested a square planar geometry for the complex.

关键词： synthesis azo compound Schiff base ligand azo and azomethine donor

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Growth Kinetics of nanocrystals and nanorods by Employing Small-angle X-ray Scattering (SAXS) and Other Techniques

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Journal of Materials Science & Technology 2008年第4期24卷 615-627页

作者： Kanishka BISWAS neenu VARGHESE c.n.R.Rao chemistry and Physics of Materials Unit DST Nanoscience Unit and CSIR Centre of Excellence in ChemistryJawaharlal Nehru Centre for Advanced Scientific ResearchJakkur P.O.Bangalore 560064India Solid State and Structural Chemistry UnitIndian Institute of ScienceBangalore 560012India chemistry and Physics of Materials Unit DST Nanoscience Unit and CSIR Centre of Excellence in ChemistryJawaharlal Nehru Centre for Advanced Scientific ResearchJakkur P.O.Bangalore 560064India

In this article, we report the results of our detailed investigations of the growth kinetics of zero-dimensional nanocrystals as well as one-dimensional nanorods by the combined use of small angel X-ray scattering （SAXS）, transmission electron microscopy （TEM） along with other physical techniques. The study includes growth kinetics of gold nanocrystals formed by the reduction of HAucl4 by tetrakis（hydroxymethyl） phosphonium chloride in aqueous solution, of cdSe nanocrystals formed by the reaction of cadmium stearate and selenium under solvothermal conditions, and of ZnO nanorods formed by the reaction of zinc acetate with sodium hydroxide under solvothermal conditions in the absence and presence of capping agents. The growth of gold nanocrystals does not follow the diffusion-limited Ostwald ripening, and instead follows a Sigmoidal rate curve. The heat change associated with the growth determined by isothermal titration calorimetry is about 10 kcal·mol^-1 per I nm increase in the diameter of the nanocrystals. In the case of cdSe nanocrystals also, the growth mechanism deviates from diffusion-limited growth and follows a combined model containing both diffusion and surface reaction terms. Our study of the growth kinetics of uncapped and poly（vinyl pyrollidone）（PVP）-capped ZnO nanorods has yielded interesting insights. We observe small nanocrystals next to the ZnO nanorods after a lapse of time in addition to periodic focusing and defocusing of the width of the length distribution. These observations lend support to the diffusion-limited growth model for the growth of uncapped ZnO nanorods. Accordingly, the time dependence on the length of uncapped nanorods follows the L3 law as required for diffusion-limited Ostwald ripening. The PVP-capped nanorods, however, show a time dependence, which is best described by a combination of diffusion （L^3） and surface reaction （L^2） terms.

关键词： Growth kinetics Gold nanocrystals cdSe nanocrystals ZnO nanorods Small angle X-ray scattering Transmission electron microscopy Ostwald ripening and sigmoidal growth

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Groundwater solute chemistry,hydrogeochemical processes and fluoride contamination in phreatic aquifer of Odisha,India

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Geoscience Frontiers 2021年第3期12卷 234-248页

作者： Sudarsan Sahu Utpal Gogoi n.c.nayak central Ground Water Board SERBhujal BhawanBhubaneswarOdishaIndia

The work investigates the major solute chemistry of groundwater and fluoride enrichment(F^(-))in the shallow phreatic aquifer of *** study also interprets the hydrogeochemical processes of solute acquisition and the genetic behavior of groundwater F^(-)contamination.A total of 1105 groundwater samples collected from across the state from different hydro-geomorphic settings have been analyzed for the major solutes and F^(-) *** is alkaline in nature(range of pH:6.6-8.7;ave.:7.9)predominated by moderately hard to very hard *** cation and anion chemistry stand in the orders of ca^(2+)>na^(+)>Mg^(2+)>K^(+) and HcO_(3)^(-)>cl^(-)>SO_(4)^(2-)>cO_(3)^(2-) *** average mineralization is low(319 mg/L).The primary water types are ca-Mg-HcO_(3) and ca-Mg-cl^(-)HcO_(3),followed by na-cl,ca-Mg-cl,and na-ca-Mg-HcO_(3)^(-)***-halite dissolution and reverse ion exchange are the significant processes of solute *** the geogenic as well as the anthropogenic sources contribute to the groundwater fluoride contamination,*** ratio of na^(+)/ca^(2+)>1.0 comprises na-HcO_(3)(cl)water types with F^(-)>1.0 mg/L(range 1.0-3.5 mg/L)where the F^(-)bears geogenic *** relations exist between F^(-)and pH,na^(+),TDS,and HcO_(3)^(-).It also reflects a perfect na-TDS correlation(0.85).The ratio of na^(+)/ca^(2+)n(F^(-)range:1.0-4.0 mg/L)with the F derived from anthropogenic *** water types include ca-Mg-HcO_(3)(cl)varieties which are recently recharged meteoritic water *** F^(-) levels exhibit poor and negative correlations with the solutes in *** na-TDS relation remains poor(0.12).In contrast,the TDS levels show strong correlations with ca^(2+)(0.91),Mg^(2+)(0.80)and even cl^(-)(0.91).The majority of the monitoring points with the anthropogenic sources of groundwater F^(-) are clustered in the Hirakud canal command area in the western parts of the state,indi

关键词： Groundwater Phreatic Aquifer Quality Odisha India

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