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parametric study of hexagonal castellated beams in post-tensioned self-centering steel connections

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Frontiers of Structural and Civil Engineering 2019年第5期13卷 1020-1035页

作者： Hassan ABEDI SARVESTANI Faculty of Water and Environmental Engineering Shahid Beheshti UniversityTehran 16589-53571Iran

The effects o f important parameters (beam reinforcing plates, initial post-tensioning, and material properties o f steel angles) on the behavior o f hexagonal castellated beams in post-tensioned self-centering (PTSC) connections undergone cyclic loading up to 4% lateral drift have been investigated by finite element (FE) analysis using ABAQUS. The PTSC connection is comprised o f bolted top and bottom angles as energy dissipaters and steel strands to provide self-centering capacity. The FE analysis has also been validated against the experimental test. The new formulations derived from analytical method has been proposed to predict bending moment o f PTSC connections. The web-post buckling in hexagonal castellated beams has been identified as the dominant failure mode when excessive initial post-tensioning force is applied to reach greater bending moment resistance, so it is required to limit the highest initial post-tensioning force to prevent this failure. Furthermore, properties o f steel material has been simulated using bilinear elastoplastic modeling with 1.5% strain-hardening which has perfectly matched with the real material of steel angles. It is recommended to avoid using steel angles with high yielding strength since they lead to the yielding o f bolt shank. The necessity o f reinforcing plates to prevent beam flange from local buckling has been reaffirmed.

关键词： finite element analysis hexagonal castellated beam parametric study post-tensioned self-centering steel connection steel moment-resisting frame

parametric Study of Low Frequency Broadband Rectilinear-to-Rotary Vibrational Energy Harvesting

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Transactions of Nanjing University of Aeronautics and Astronautics 2018年第1期35卷 1-9页

作者： Chen Jingfan Deng Wei Wang Ya Inman Dan Department of Mechanical Engineering Stony Brook University Department of Mechanical Engineering Texas A&M University Department of Aerospace Engineering University of Michigan

A parametric study of a high-power-density dual resonator for achieving low frequency broadband electromagnetic energy harvesting is *** dual resonator consists of a rectilinear oscillator(R_LO)performing magnetic levitation and a rotary oscillator(R_TO)performing electromagnetic coupling through a stator and a *** oscillators,coupled by magnetic forces generated by a set of arc permanent magnets,radially magnetized and centro-symmetrically fixed onto the R_LO and the rotor of the R_TO achieve the reciprocating-to-rotary motion conversion and frequency ***,the dual resonator is able to convert stochastic reciprocating motion into controllable rotation,provide intrinsic frequency up-conversion,use non-contact magnetic coupling to provide near loss-free energy transfer and be configured into specific applications to obtain and maintain high-energy orbits of multi-stable energy *** solely focusing on developing a dual resonator provides substantial benefits,its dynamic behavior is unclear,thus electromagnetic-dynamic governing equations are derived,and a curve fitting model of restoring torque of R_TO under different repulsive magnets configurations are developed to predict key characteristics and to improve performance of the electromechanical *** analysis is carried out for providing aquantitative guidance of customizing the harvester to achieve an optimal power density.

关键词： curve fitting model non-contact rectilinear-to-rotary motion transformation frequency up-conversion systematic modeling parametric study

parametric logic: Foundations

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Science China Mathematics 1995年第8期38卷 1009-1024页

作者：林作铨李未 Department of Computer Science Shantou University Shantou 515063 China Department of Computer Science Beijing University of Aeronautics and Astronautics Beijing 100080 China

parametric logic is introduced. The language, semantics and axiom system of parametric logic are defined. Completeness theorem of parametric logic is provided. parametric logic has formal ability powerful enough to ca... 详细信息

关键词： parametric logic generic modal logic first-order logic.

Smoothing parametric Design of Addendum Surfaces for Sheet Metal Forming

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Chinese Journal of Mechanical Engineering 2020年第1期33卷 75-82页

作者： Jixing Li Tao Ning Ping Xi Bifu Hu Tian Wang Jiong Yang School of Mechanical Engineering and Automation Beihang UniversityBeijing 100192China School of Mechanical Engineering Zhengzhou UniversityZhengzhou 450001China

The manual design of addendum surfaces on common CAD platforms is very tedious which requires many trialscorrections,which will certainly a ect the construction e ciency and quality of addendum surfaces,and then a ect the formability and quality of the workpiece in the process of sheet *** this paper,an automatic procedure based on parametric design method is proposed for the rapid construction of the addendum *** kernel of the parametric method is constructing boundary curves based on the shape of surfaces of workpiece and designing guide curves based on Hermite curve *** some simple parameters,the shape of the addendum surfaces could be controlled and adjusted *** addition,a minimum energy optimization method is employed to further optimize the constructed addendum surface.A finite element analysis for the sheet forming process is performed to evaluate the forming quality of constructed addendum *** instance illustrates that the addendum surface constructed by the proposed method could ensure both the overall smoothing of surfaces and the final forming quality,and it has a good e ect on springback after *** research proposes a smoothing parametric design method for addendum surfaces construction which could construct and optimize addendum surfaces rapidly.

关键词： CAD/CAM parametric design Curve optimization Addendum surface Sheet forming

A novel approach towards parametric assessment of reliability and resilience of high voltage mica-based insulation systems by statistical analysis of experimental failure data

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High Voltage 2024年第2期9卷 495-507页

作者： Shahram Negari Davoud Esmaeil Moghadam Integrated Power Services ClevelandOhioUSA Valeo eAutomotive Germany GmbH ErlangenGermany

Insulation systems in high-voltage electric machines play a pivotal role in the reliable operation and longevity of the ***-based insulation materials have proven to possess and maintain excellent dielectric properties in the long run and prevent premature insulation *** qualifications tests,such as voltage endurance,are outlined in IEC and IEEE *** authors,however,take a different parametric approach,opting for reliability assessment of insulation systems using derived three-parameter Weibull ***,instead of simple pass–fail criteria,empirical data is employed to determine failure rate probabilities quantitatively and *** data,including breakdown,dissipation factor,and partial discharge mea-surements,are used to construct the Weibull distribution model to predict fault and failure rates and calculate hazard *** rigorous examinations interpreted through the analytical model help assess insulation system resilience and particularly the impact of electrical field stress and mica *** of electrical stress from 66.75 to 71.20 V/mil demonstrated how the mean time to failure of the system changed from 146.4 to 85.1 at 3 Un,hence identifying opportunities for design improvement and uncovering performance ***,the developed framework enhances comprehension of insulation system failure probabilities,guiding design decisions and ensuring a secure and reliable operation of electrical machines across applications.

关键词： insulation parametric approach

Global optimal polynomial approximation for parametric problems in power systems

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Journal of Modern Power Systems and Clean Energy 2019年第3期7卷 500-511页

作者： Yongzhi ZHOU Hao WU Chenghong GU Yonghua SONG College of Electrical Engineering Zhejiang UniversityHangzhouChina Department of Electrical and Electronics Engineering University of BathBathU.K. Department of Electrical and Computer Engineering University of MacaoMacaoChina

The influence of parameters on system states for parametric problems in power systems is to be *** parameters could be renewable generation outputs,load factor, etc. Polynomial approximation has been applied to express the nonlinear relationship between system states and parameters, governed by the nonlinear and implicit equations. Usually, sampling-based methods are applied, e.g., data fitting methods and sensitivity methods,etc. However, the accuracy and stability of these methods are not guaranteed. This paper proposes an innovative method based on Galerkin method, providing global optimal approximation. Compared to traditional methods, this method enjoys high accuracy and stability. IEEE 9-bus system is used to illustrate its effectiveness, and two additional studies including a 1648-bus system are performed to show its applications to power system analysis.

关键词： parametric problems Polynomial approximation Galerkin method Global approximation Optimal approximation Load flow problems

Gyroscopic modes decoupling method in parametric instability analysis of gyroscopic systems

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Acta Mechanica Sinica 2018年第5期34卷 963-969页

作者： Y.J.Qian X.D.Yang H.Wu W.Zhang T.Z.Yang College of Mechanical Engineering Beijing University of TechnologyBeijing 100124China Department of Mechanics Tianjing UniversityTianjing 300072China

Traditional procedures to treat vibrations of gyroscopic continua involve direct application of perturbation methods to a system with both a strong gyroscopic term and other weakly coupled *** this study,a gyroscopic modes decoupling method is used to obtain an equivalent system with decoupled gyroscopic modes having only weak *** the axially moving string as an example,the instability boundaries in the vicinity of parametric resonances are detected using both the traditional coupled gyroscopic system and our system with decoupled gyroscopic modes,and the results are compared to show the advantages and disadvantages of each method.

关键词： Axially moving material Decoupling of gyroscopic modes parametric instability Perturbation method Gyroscopic system

parametric STUDY OF RAMAN FREE-ELECTRON LASER

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中国科学A辑(英文版) 1988年第3期31卷 379-384页

作者：褚成陆载通施瑞根王之江 Shanghai Institute of Optics and Fine Mechanics Academia Sinica Academia Sinica

Experimental study has been carried out for parametric optimization of our Raman free-electron laser (FEL). The optimum FEL operating conditions have been determined, under which performances of the FEL are improved significantly. The electronic efficiency of the FEL has been increased by about an order of magnitude to 0.8% for a cusp wiggler and 1.4% for an electromagnetic wiggler. The FEL has exhibited excellent wavelength tunability with a tuning range of 5—9 mm for the cusp wiggler and 6—12 mm for the electromagnetic wiggler. Experimental results are in good agreement with theoretical predictions.

关键词： tuning LASER lasing magnitude drift pumping parametric length preliminary waveform

Optoelectronic parametric oscillator

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Light(Science & Applications) 2020年第1期9卷 1028-1037页

作者： Tengfei Hao Qizhuang Cen Shanhong Guan Wei Li Yitang Dai Ninghua Zhu Ming Li State Key Laboratory on Integrated Optoelectronics Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and TelecommunicationsBeijing 100876China

Oscillators are one of the key elements in various applications as a signal source to generate periodic *** them,an optical parametric oscillator(OPO)is a driven harmonic oscillator based on parametric frequency conversion in an optical cavity,which has been widely investigated as a coherent light source with an extremely wide wavelength tuning ***,steady oscillation in an OPO is confined by the cavity delay,which leads to difficulty in frequency tuning,and the frequency tuning is discrete with the minimum tuning step determined by the cavity ***,we propose and demonstrate a counterpart of an OPO in the optoelectronic domain,i.e.,an optoelectronic parametric oscillator(OEPO)based on parametric frequency conversion in an optoelectronic cavity to generate microwave *** to the unique energy-transition process in the optoelectronic cavity,the phase evolution in the OEPO is not linear,leading to steady single-mode oscillation or multimode oscillation that is not bounded by the cavity ***,the multimode oscillation in the OEPO is stable and easy to realize owing to the phase control of the parametric frequency-conversion process in the optoelectronic cavity,while stable multimode oscillation is difficult to achieve in conventional oscillators such as an optoelectronic oscillator(OEO)or an OPO due to the mode-hopping and mode-competition *** proposed OEPO has great potential in applications such as microwave signal generation,oscillator-based computation,and radio-frequency phase-stable transfer.

关键词： effect oscillator parametric