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A New Method to Analyse Two-Side tapered Waveguides

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Chinese Physics Letters 2005年第9期22卷 2394-2395页

作者：范国芳宁继平尚连聚韩群陈志强 College of Precision Instrument and Optoelectronics Engineering Tianjin University Tianjin 300072

We discuss the characters of two-side tapered waveguides. Then, based on some approximations, a simple but practical and efficient method is developed to design the taper waveguide. The results are compared with other... 详细信息

关键词： Fig Ti tapered

Transverse free vibration analysis of a tapered Timoshenko beam on visco-Pasternak foundations using the interpolating matrix method

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Earthquake Engineering and Engineering Vibration 2019年第3期18卷 567-578页

作者： Zhang Jinlun Ge Renyu Zhang Liaojun Institute of Engineering Safety and Disaster Prevention Hohai University Nanjing 210098 China Key Laboratory for Mechanics Anhui Polytechnic University Wuhu 241000 China

The characteristics of transverse free vibration of a tapered Timoshenko beam under an axially conservative compression resting on visco-Pasternak foundations are investigated by the interpolating matrix method. The research is executed in view of a three-parameter foundation which includes the eff ects of the Winkler coeffi cient, Pasternak coeffi cient and damping coeffi cient of the elastic medium. The governing equations of free vibration of a non-prismatic Timoshenko beam under an axially conservative force resting on visco-Pasternak foundations are transformed into ordinary diff erential equations with variable coeffi cients in light of the bending rotation angle and transverse displacement. All the natural frequencies orders together with the corresponding mode shapes of the beam are calculated at the same time, and a good convergence and accuracy of the proposed method is verifi ed through two numerical examples. The infl uences of foundation mechanical characteristics together with rotary inertia and shear deformation on natural frequencies of the beam with diff erent taper ratios are analyzed. A comprehensive parametric numerical study is carried out emphasizing the primary parameters that describe the dynamic property of the beam.

关键词： interpolating matrix method vibration analysis tapered Timoshenko beam visco-Pasternak foundation

Generating quasi-single-cycle THz pulse from frequency-chirped electron bunch train and a tapered undulator

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High Power Laser Science and Engineering 2016年第1期4卷 5-8页

作者： Zhuoran Ma Zhe Wang Feichao Fu Rui Wang Dao Xiang Key Laboratory for Laser Plasmas (Ministry of Education) Department of Physics and AstronomyShanghai Jiao Tong University IFSA Collaborative Innovation Center Shanghai Jiao Tong University

We propose a proof-of-principle experiment to test a new scheme to produce a single-cycle radiation pulse in free-electron lasers(FELs). Here, a few α-BBO crystals will be first used to produce an equally spaced laser pulse ***, the laser pulse train illuminates the cathode to produce a frequency-chirped electron bunch train in a photocathode rf gun. Finally, the frequency-chirped electron bunch train passes through a tapered undulator to produce a quasi-single-cycle THz pulse. This experiment should allow comparison and confirmation of predictive models and scaling laws, and the preliminary experimental results will also be discussed.

关键词： electron bunch train single-cycle THz pulse tapered undulator

Heat transfer in a tapered fluidized bed of biomass particles with pulsed gas flow

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Particuology 2019年第1期17卷 2-14页

作者： Dening Jia Xiaotao Bi C. Jim Lim Shahab Sokhansanj Atsushi Tsutsumi Department of Chemical and Biological Engineering The University of British Columbia2360 East MallVancouverBCV6T 1Z3Canada Environmental Sciences Division Oak Ridge National LaboratoryOak RidgeTN 37831USA Collaborative Research Center for Energy Engineering Institute of Industrial ScienceThe University of Tokyo4-6-1 KomabaMeguro-kuTokyo 153-8505Japan

Bed-to-surface heat transfer of pure biomass particles in a pulsed fluidized bed with a tapered bottom section was investigated. Three biomass species — Douglas fir, pine, and switchgrass — were studied under various operating conditions. Their heat transfer coefficients were found to be closely associated with hydrodynamics dominated by gas pulsations. A higher superficial gas velocity generally yielded better gas–solid contact and higher heat transfer rates. A moderately increasing pulsation frequency promoted convective heat transfer of particles but also reduced pulsation intensity, leading to undesired flow behaviours such as channelling and partial defluidization. The study of the pulsation duty cycle revealed that, for cohesive particles, a smaller duty cycle was preferred to generate powerful pulsations to break up inter-particle forces. Moreover, a duty cycle increase allowed higher gas throughput as long as a suitable fluidization was maintained. The addition of finer particles to a coarse fraction increased particle mobility, and subsequently heat transfer, which also explained the higher heat transfer coefficients of switchgrass as it contained more fines compared with fir and pine. Experimental results in the tapered bed were also compared with those of non-tapered geometry where a 10%–20% increase in heat transfer was observed.

关键词： Fluidized bed Gas pulsations tapered column Heat transfer Biomass

New tapered metallic stent for unresectable malignant hilar bile duct obstruction

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World Journal of Clinical Cases 2015年第10期3卷 887-893页

作者： Yuji Sakai Toshio Tsuyuguchi Takao Nishikawa Harutoshi Sugiyama Reina Sasaki Dai Sakamoto Yuto Watanabe Masato Nakamura Shin Yasui Rintaro Mikata Osamu Yokosuka Department of Gastroenterology and Nephrology Graduate School of Medicine Chiba University

AIM: To examine the usefulness of a new tapered metallic stent(MS) in patients with unresectable malignant hilar bile duct ***: This new tapered MS was placed in 11 patients with Bismuth Ⅱ or severer unresectable malignant hilar bile duct obstruction, as a prospective study. The subjects were six patients with bile duct carcinoma, three with gallbladder cancer, and two with metastatic bile duct obstruction. Stenosis morphology was Bismuth Ⅱ: 7, Ⅲa: 3, and Ⅳ: 1. UMIN Clinical Trial Registry(UMIN000004758).RESULTS: MS placement was 100%(11/11) successful. There were no procedural accidents. The mean patency period was 208.401 d, the median survival period was 142.000 d, and the mean survival period was 193.273 d. Occlusion rate was 36.4%(4/11); the causes of occlusion were ingrowth and overgrowth in 2 patients each, 18.2%, respectively. Patients with occlusion underwent endoscopic treatment one more time and all were treatable. CONCLUSION: The tapered MS proved useful in patients with unresectable malignant hilar bile duct obstruction because it provided a long patency period, enabled re-treatment by re-intervention, and no procedural accidents occurred.

关键词： Malignant hilar bile duct obstruction Metallic stent tapered metallic stent

THE EFFECT OF CONDITIONAL PARAMETERS ON tapered DIE SUPERPLASTIC EXTRUSION

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Chinese Science Bulletin 1992年第3期37卷 245-249页

作者：宋玉泉李焕海李正 Research Institute of Superplasticity Jilin University of Technology Changchun 130025 PRC

Ⅰ. INTRODUCTION A series of problems raised in the application of technology of superplastic extrusion formation are in need of giving general answers and guiding principles with theory of mechanics, a typical one, for instance, is the effect on extrusion with regard to conditional parameters. According to 'The theoretical analysis of superplastic extrusion through ta-

关键词： superplastcity tapered die conditional parameter extrusion

Millimeter wave dielectric loaded exponentially tapered slot antenna array using substrate integrated waveguide for gigabit wireless communications

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红外与毫米波学报 2015年第5期34卷 513-519页

作者： S Ramesh T Rama Rao Department of Electronics & communication Engineering Valliammai Engineering College RADMIC Department of Telecommunication EngineeringSRM University

A new and upcoming application is the use of 60 GHz antennas for high date rate point-to-point connections to serve Gigabit(Gi-Fi)w ireless *** design of M illimeter w ave(M m W)antennas has to cope w ith the unadorned influences of manufacturing tolerances and losses at 60 *** this paper,the concept of Substrate Integrated Waveguide(SIW)and Exponentially tapered Slot(ETS)antenna w ere used together to design a high gain,efficient planar dielectric loaded antenna for M m W Gi-Fi w ireless communications at 60 *** SIW is used to feed the antenna and a dielectric is utilized in front of the antenna to increase the *** dielectric loaded ETS antenna and compact SIW feed w ere fabricated on a single substrate,resulting in low cost and easy *** antenna w ith elliptical shaped dielectric loaded w as fabricated using printed circuit board *** measured gain of the single element antenna is 10.2 dB,w hile the radiation efficiency of 96.84%is obtained at 60 *** Y-junction SIW pow er divider is used to form a 1×4 array structure.M easured gain of the 1×4 array antenna is 13.3 dB,w hile the measured radiation pattern and gain are almost constant w ithin the w ide bandw idth of the antenna.

关键词： millimeter waves 60 GHz exponentially tapered slot antenna dielectric loading substrate integrated waveguide

Absorption saturation measurement using the tapered optical nanofiber in a hot cesium vapor

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Chinese Optics Letters 2019年第3期17卷 71-74页

作者： Zixuan Song Xingyu Yue Yu Luo Haodong Li Yanting Zhao State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Laser SpectroscopyShanxi University Collaborative Innovation Center of Extreme Optics Shanxi University College of Physics and Electronics Engineering Shanxi University

We report the observation of ultralow-power absorption saturation in a tapered optical fiber(TOF) mounted in a hot cesium(Cs) vapor in a vacuum chamber. The small optical mode area of TOF produces a great influence on optical properties, allowing optical interactions with nanowatt-level power. The comparison of transmission characteristics for the TOF system and free-space vapor is investigated at different input power and atomic density. The unique performance of the Cs-TOF system makes it a promising candidate in resonant nonlinear optical applications with ultralow power.

关键词： Absorption saturation measurement tapered optical nanofiber cesium vapor

Buckling Analysis of tapered Continuous Columns by Using Modified Buckling Mode Shapes

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Journal of Marine Science and Application 2019年第2期18卷 160-166页

作者： Sina Toosi Akbar Esfandiari Ahmad Rahbar Ranji Department of Ocean Engineering AmirKabir University of Technology

Elastic critical buckling load of a column depends on various parameters,such as boundary conditions,material,and crosssection *** main purpose of this work is to present a new method for investigating the buckling load of tapered columns subjected to axial *** proposed method is based on modified buckling mode shape of tapered structure and perturbation *** mode shape of the damaged structure can be expressed as a linear combination of mode shapes of the intact *** in length in piecewise form can be positive or *** method can be used for single-span and continuous *** of results with those of finite element and Timoshenko methods shows the high accuracy and efficiency of the proposed method for detecting buckling load.

关键词： Buckling analysis tapered column.Continuous columns Finite element method Modified buckling mode shapes