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Vibration Characteristics and Power Transmission of Coupled Rectangular Plates with Elastic Coupling Edge and Boundary Restraints

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Chinese Journal of Mechanical Engineering 2012年第2期25卷 262-276页

作者： CHEN Yuehua JIN Guoyong DU Jingtao LIU Zhigang College of Power and Energy Engineering Harbin Engineering UniversityHarbin 150001China

Coupled-plate structures are widely used in the practical engineering such as aeronautical,civil and naval engineering etc.Limited works can be found on the vibration of the coupled-plate structure due to the increased mathematical complexity compared with the single plate structure.In order to study analytically the vibration characteristics and power transmission of the coupled-plate structure,an analytical model consisting of three coupled plates elastically restrained along boundary edges and elastically coupled with arbitrary angle is considered,in which four groups of springs are distributed consistently along each edge of the model to simulate the transverse shearing forces,bending moments,in-plane longitudinal forces and in-plane shearing forces separately.With elastic coupling condition and general boundary condition of both flexural and in-plane vibrations taken into account by setting the stiffness of corresponding springs,the double Fourier series solution to the dynamic response of the structure was obtained by employing the Rayleigh-Ritz method.In order to validate the model,the natural frequency and velocity response of the model are firstly checked against results published in literatures and the ANSYS data,and good agreement was observed.Then,numerical simulation of the effects of several relevant parameters on the vibration characteristics and power transmission of the coupled structure were performed,including boundary conditions,coupling conditions,coupling angle,and location of the external forces.Vibration and energy transmission behaviors were analyzed numerically.The results show that the power transmission can be significantly influenced by the boundary restraints and the location of excitation.When the excitation is located at the central symmetry point of the model,the energy flow shows a symmetrical distribution.Once the location deviates from the central symmetry point,the power circumfluence occurs and the vortex energy field is formed at high frequency.

关键词： vibration power transmission coupled-plate structure elastic restraints

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Broadband ferromagnetic resonance studies on influence of interface bonding on magnetoeletric effects in ferrit e-ferroelectric composites

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Frontiers of physics 2012年第4期7卷 418-423页

作者： D.V.B.Murthy Gopalan Srinivasan Physics Department Oakland UniversityRochesterMI 48309USA

A systematic study has been carried out on the effects of interface bonding on the strain mediated magnetoelectric （ME） coupling in ferromagnetic-ferroelectric bilayers. The technique used involves the static electric field E tuning of the ferromagnetic resonance （FMR） in yttrium iron garnet （YIG） and lead zirconate titanate （PZT） or lead magnesium niobate-lead titanate （PMN-PT）. A broad band detection technique has been developed for studies over 1 40 GHz in three types of bilayers： epoxy bonded, eutectic bonded and YIG films directly grown onto piezoelectric substrate by electrophoretic deposition. The strength A of the converse ME effect （CME） defined as the ratio of the frequency shift 8f in FMR in E, A = 8f/E, varies over the range 0.8 to 4.3 MHz.cm/kV, and is the highest for eutectic bonded samples and is the weakest for epoxy bonded bilayers. The results presented here as of importance for dual electric and magnetic field tunable ferrite ferroelectric microwave resonators and filters.

关键词： Keywords ferrite ferroelectric magnetoelectric ferromagnetic resonance

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Numerical simulation of broken pin effects on the flow field and cooling performance of a double-wall cooling configuration

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Chinese Journal of Aeronautics 2021年第2期34卷 358-375页

作者： Wenjing GAO Honglin LI Lei LI Zhe’nan ZHAO Zhufeng YUE Department of Engineering Mechanics Northwestern Poly technical UniversityXian 710129China

In this paper, the flow characteristics of the double wall structure are presented and the effect of the broken pin size on the cooling performance and flow field of the double wall configuration is investigated. A periodic plate model with seven units is adopted, and there are an impingement hole and a film hole in each unit. Under five blowing ratios, six different sizes of the broken pin are compared, and the double wall configuration without broken pins is taken as the baseline.The results show that if the broken pins height is too small, the cooling effectiveness usually cannot be improved. With the presence of broken pins with a height of more than 0.4, the effectiveness is improved due to the enhancement of reattachment and recirculation of coolant. With the increase of the broken pin height, the cooling effectiveness increases. However, the increase of the diameter does not always improve the cooling performance, since the limiting effect of the wall jet. In this study, Case 6 with the largest broken pin always has the best cooling performance, but also the largest flow resistance. In Case 6 temperature is reduced by almost 15 K compared to the baseline, and more areas have relatively higher cooling effectiveness.

关键词： Broken pin Computational Fluid Dynamics Cooling performance Double wall configuration Turbine blades

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Recent Progress in Heavy Fuel aviation Piston Engine

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Transactions of Nanjing university of Aeronautics and Astronautics 2015年第1期32卷 22-28页

作者：陈伟周健豪何小明 College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics

Heavy fuel aviation piston engines(HF-APEs)refer to the engine using fuels with high flash point,such as kerosene or light diesel.Here technique specifications of some classical foreign HF-APEs(Hirth3503,Zanzottera 498)are introduced.Recent progress and trend of fuel injection,fuel ignition,working cycle,intake charging,thermal management and electronic control of HF-APE are compared and summarized.Emphases are put on the technological difficulties,solutions and development tendency in the design,retrofitting and manufacturing of HF-APE aiming to provide references for the research of related area and the development of prototype HF-APE in China.

关键词： heavy fuel aviation piston engine direct injection electronic control

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Influence of longitudinal-torsional ultrasonic-assisted vibration on micro-hole drilling Ti-6Al-4V

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Chinese Journal of Aeronautics 2021年第9期34卷 247-260页

作者： Guofu GAO Ziwen XIA Zhaojie YUAN Daohui XIANG Bo ZHAO School of Mechanical and Power Engineering Henan Polytechnic UniversityJiaozuo 454000China

As Ti-6 Al-4 V is a typical hard to machine material,especially in micro drilling aviation parts,chip breaking difficulty is of increasing interest to explore its further development.In this study,Longitudinal-Torsional Ultrasonic Assisted Drilling(LTUAD)was employed to machine Ti-6 Al-4 V,and its feasibility was evaluated by comparing with Conventional Drilling(CD).By combining periodical characteristics and vibration models(the separated or the unseparated ultrasonic elliptical vibration),the influence of ultrasonic frequency on the intersection characteristics of trajectories were analyzed.And the intersection characteristics were divided into four categories:even periodicity,odd periodicity,non-odd and even periodicity and composite periodicity,indicating different capability for chip breaking.By applying the longitudinal-torsional compound vibration horn,the micro-hole drilling experiment was carried out on machining center.The chip morphology,the thrust force,and the burr height were discussed.Experimental results showed that the morphology of chips presented as smaller and more fragmentary ones in LTUAD compared with continuous helical conical ones and fold-shaped ones in CD.Compared with CD,the average values of the thrust force in LTUAD reduced by 1.98%to 24.9%.According to the burr around the hole exit in both LTUAD and CD,the height of the latter was greatly affected by the drilling parameters.And the burr around the exit of the hole were distributed rather evenly with smaller extension in LTUAD.Consequently,the LTUAD employed in micro-hole drilling was effective.

关键词： Capability for chip breaking Longitudinal-torsional ultrasonic assisted drilling Micro-hole drilling Periodical characters Ti-6Al-4V

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Mid-infrared superabsorbers based on quasi-periodic moiré metasurfaces

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Chinese Optics Letters 2018年第5期16卷 12-16页

作者：刘耀然伍子龙 Eric H.Hill 郑跃兵 Department of Mechanical Engineering and Texas Materials Institute The University of Texas at Austin

We report on mid-infrared superabsorbers based on quasi-periodic moiré metasurfaces in metal-insulator-metal form. By varying the spacer thickness, moiré rotation angle, and filling factor of the superabsorbers, we can tune narrowband or broadband absorption in a systematic way. With their high tunability of near-unity absorption and simple fabrication, in combination with decoupled mode theory for an efficient design, moiré superabsorbers are well-suited for a wide range of applications in sensing, imaging, and communication.

关键词： Mid-infrared superabsorbers based on quasi-periodic moir metasurfaces

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Determination of the Place of Implementation of a Biorefinery Based on Logistics Parameters

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Journal of Power and Energy Engineering 2022年第5期10卷 22-38页

作者： Shara K. M. J. Leal Yordanka R. Cruz Vinicius Rossa Gisel Ch. Díaz Yedier R. Padrón Donato A. G. Aranda Rene G. Carlíz School of Chemistry Federal University of Rio de Janeiro Rio de Janeiro Brazil Institute of Chemistry Fluminense Federal University Niterói Brazil

Airlines and the aviation industry are committed to emission reduction targets. Biokerosene was pointed out as one of the key elements to achieving this goal. The use of oilseeds in the production of biokerosene is interesting due to the great Brazilian experience in the production of biofuels from this raw material. In view of this scenario, this dissertation has as its main objective the definition of the place of implantation of a biorefinery in Brazilian territory that has aviation biokerosene as its main product. For this, data on supply and demand for fossil aviation kerosene in Brazilian regions were collected, an extensive review was carried out in scientific articles on the oleaginous raw materials used for the production of this biofuel, and logistical parameters were selected and used as criteria for that selection. The oilseeds selected for the production of biofuel were macaúba and soybean and the state was chosen for the implementation of the biorefinery was Goiás. Based on logistical parameters, the city of Formosa (GO) was selected to host the biorefinery. The soybean crushers located in Luziania, Anápolis, Ipameri, and Itumbiara were chosen as suppliers of soybean oil and the city of Formosa (GO) as the headquarters for the commercial planting of macaúba. The destination of this fuel will be Petrobrás Distribuidora S.A., an aviation fuel distributor authorized by the ANP based in the city of Brasília (DF).

关键词： Biokerosene Biofuels Oilseeds Biorefinery aviation

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Speckle reduction of SAR images using ICA basis enhancement and separation

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Chinese Optics Letters 2007年第9期5卷 509-512页

作者：李昱彤周越 Institute of Image Processing and Pattern Recognition Shanghai Jiao Tong University

An approach for synthetic aperture radar （SAR） image de-noising based on independent component analysis （ICA） basis images is proposed. Firstly, the basis images and the code matrix of the original image are obtained using ICA algorithm. Then, pointwise Hoder exponent of each basis is computed as a cost criterion for basis enhancement, and then the enhanced basis images are classified into two sets according to a separation rule which separates the clean basis from the original basis. After these key procedures for speckle reduction, the clean image is finally obtained by reconstruction on the clean basis and original code matrix. The reconstructed image shows better visual perception and image quality compared with those obtained by other traditional techniques.

关键词： Algorithms Image quality Independent component analysis Speckle Synthetic aperture radar

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Pressure-dependent phase transition of 2D layered silicon telluride(Si2le3)and manganese intercalated silicon telluride

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Nano Research 2019年第9期12卷 2373-2377页

作者： Virginia L. Johnson Auddy Anilao Kristie J. Koski Department of Chemistry University of CaliforniaDavisDavisCA 95616USA

Two-dimensional(2D)layered silicon telluride(SizTes)nanocrystals were compressed to 12 GPa using diamond anvil cell techniques.Optical measurements show a color change from transparent red to opaque black indicating a semiconductor-to-metal phase transition.Raman scattering was used to observe the stiffening of the crystal lattice and subsequent phase behavior.A possible phase transition was observed.at 9.5±0.5 GPa evidenced by the disappearance of the Atg stretching mode.SizTes was intercalated with elemental manganese to^1 at.%.Intercalation lowers the pressure of the proposed phase transition to 7.5±1 GPa.Raman modes show both phonon stiffening and phonon softening,suggesting negative linear compressibility.These results provide fundamental insight into the high-pressure optical phonon behavior of silicon telluride and illuminate how a specific electron-donating intercalant can chemically alter pressure-dependent optical phonon behavior.

关键词： silicon telluride Si2Te3 high pressure diamond anvil cell two-dimensional(2D)layered material

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Facile synthesis of GO as middle carrier modified flower-like BiOBr and C_(3)N_(4) nanosheets for simultaneous treatment of chromium(Ⅵ)and tetracycline

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Chinese Chemical Letters 2021年第7期32卷 2187-2191页

作者： Liushan Jiang Yu Xie Fan He Yun Ling Jinsheng Zhao Hao Ye Shiqian Li Yang Hou College of Environment and Chemical Engineering Nanchang Hangkong UniversityNanchang 330063China Key Laboratory of Biomass Chemical Engineering of Ministry of Education College of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310027 China College of Chemistry and Chemical Engineering Liaocheng UniversityLiaocheng 252059China Ningbo Research Institute Zhejiang UniversityNingbo 315100China

A novel GO modified g-C_(3)N_(4) nanosheets/flower-like BiOBr hybrid photocatalyst is fabricated by a facile method.The characterization results reveal that wrinkled GO is deposited between g-C_(3)N_(4) nanosheets and flower-like BiOBr forming a Z-scheme heterojunction.As a mediator,plicate GO plays a positive role in prompting photogene rated electrons transfe rring through its sizeable 2 D/2 D contact surface area.The g-C3 N4/GO/BiOBr hybrid displays a superior photocatalytic ability to g-C_(3)N_(4) and BiOBr in photodegrading tetracycline(TC),whose removal efficiency could reach 96%within 2 h.Besides,g-C_(3)N_(4)/GO/BiOBr composite can reduce Cr(Ⅵ),and simultaneously treat TC and Cr(Ⅵ)combination contaminant under the visible light The g-C_(3)N_(4)/GO/BiOBr ternary composite also exhibits satisfactory stability and reusability after four cycling experiments.Further,a feasible mechanism related to the photocatalytic process of gC_(3)N_(4)/GO/BiOBr is put forward.This study offers a te rnary hybrid photocatalyst with eco-friendliness and hopeful application in water pollution.

关键词： Z-scheme g-C_(3)N_(4)/GO/BiOBr Ternary heterojunction Photocatalysis Tetracycline degradation Cr(Ⅵ)reduction

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