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Analytical formula of rectangular surface mobility of an infinite plate and the parameters influences
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作者 DAI Jue(Shenzhen Polytechnic Shenzhen 518055) 《Chinese Journal of Acoustics》 2003年第1期59-67,共9页
This paper investigates the characteristics of surface mobility when power transmission over the contact area between sub-structures is considered. An analytical formula of the surface mobility of an infinite homogene... This paper investigates the characteristics of surface mobility when power transmission over the contact area between sub-structures is considered. An analytical formula of the surface mobility of an infinite homogeneous plate over a rectangular contact area subject to a uniform, conphase force excitation is derived by using complex power method and the concept of structural intensity. This formula provides a theoretical tool for investigating power transmission over the contact area between sub-structures. The influences of the size, the dimension and the aspect ratio of the contact area on power transmission are analyzed and described according to the results calculated, that provides an effectively theoretical method for investigation of vibration isolation. 展开更多
关键词 of it on for area BE Analytical formula of rectangular surface mobility of an infinite plate and the parameters influences is into
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A METHOD OF ESTIMATING THE INFLUENCE OF EXPERIMENTAL ERRORS ON THE EXPERIMENTAL RESULTS OF MATERIAL PARAMETERS AND THE CRITERIA TO VALUE THIS INFLUENCE
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作者 Yao Weixing Tsinghua University 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 1991年第3期320-325,共6页
In this paper the main sources causing the scatter of the experimental results of the material parameters are discussed. They can be divided into two parts: one is the experimental errors which are introduced because ... In this paper the main sources causing the scatter of the experimental results of the material parameters are discussed. They can be divided into two parts: one is the experimental errors which are introduced because of the inaccuracy of experimental equipment, the experimental techniques, etc., and the form of the scatter caused by this source is called external distribution. The other is due to the irregularity and inhomogeneity of the material structure and the randomness of deformation process. The scatter caused by this source is inherent and then this form of the scatter is called internal distribution. Obviously the experimental distribution of material parameters combines these two distributions in some way; therefore, it is a sum distribution of the external distribution and the internal distribution. In view of this , a general method used to analyse the influence of the experimental errors on the experimental results is presented, and three criteria used to value this influence are defined. An example in which the fracture toughness KIC is analysed shows that this method is reasonable, convenient and effective. 展开更多
关键词 A METHOD OF ESTIMATING THE influence OF EXPERIMENTAL ERRORS ON THE EXPERIMENTAL RESULTS OF MATERIAL parameters AND THE CRITERIA TO VALUE THIS influence
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Influences of uncertain parameters on groundwater contaminant transport modeling
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《Global Geology》 1998年第1期99-100,共2页
关键词 influences of uncertain parameters on groundwater contaminant transport modeling
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Parameters analysis and application of the differential excitation detection technology
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作者 于霞 张卫民 +2 位作者 陈国龙 邱忠超 曾卫琴 《Journal of Beijing Institute of Technology》 EI CAS 2015年第3期348-354,共7页
A differential excitation probe based on eddy current testing technology was designed. Sheet specimens of Q 235 steel with prefabricated micro-cracks of different widths and of aluminum with prefabricated micro-cracks... A differential excitation probe based on eddy current testing technology was designed. Sheet specimens of Q 235 steel with prefabricated micro-cracks of different widths and of aluminum with prefabricated micro-cracks of different depths were detected through the designed detection system. The characteristics of micro-cracks can be clearly showed after signals processing through the short-time Fourier transform( STFT). By changing the parameter and its value in detecting process,the factors including the excitation frequency and amplitude,the lift-off effect and the scanning direction were discussed,respectively. The results showed that the differential excitation probe was insensitive to dimension and surface state of the tested specimen,while it had a high degree of recognition for micro-crack detection. Therefore,when the differential excitation detection technology was used for inspecting micro-crack of turbine blade in aero-engine,and smoothed pseudo Wigner-Ville distribution was used for signal processing,micro-cracks of 0. 3 mm depth and 0. 1 mm width could be identified. The experimental results might be useful for further research on engineering test of turbine blades of aero-engine. 展开更多
关键词 differential excitation probe eddy current testing micro-crack defect influence parameters analysis
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Seed Recalcitrance:a Current Assessment 被引量:4
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作者 宋松泉 Patricia BERJAK +2 位作者 Norman PAMMENTER Tobias M.NTULI 傅家瑞 《Acta Botanica Sinica》 CSCD 2003年第6期638-643,共6页
Seeds have been categorized as orthodox, recalcitrant and intermediate seeds according to their dehydration behaviors. Identification of desiccation-tolerance and -sensitivity of seeds is the basis making storage stra... Seeds have been categorized as orthodox, recalcitrant and intermediate seeds according to their dehydration behaviors. Identification of desiccation-tolerance and -sensitivity of seeds is the basis making storage strategy of seeds and long-term conservation of species gene resources. In addition to the inherent characteristics of the species, developmental status of the seeds, dehydration rate, and the conditions under which they are dried and subsequently re-imbibed are very important factors influencing desiccation tolerance of seeds. Survival, electrolyte leakage rate, and germination/growth rate produced by survived seeds are a excellent synthetic parameter when discussing desiccation tolerance of seeds. Desiccation tolerance of seeds is a quantitative feature. The term 'critical water content' is incorrect and has caused some confusion in assessment of seed recalcitrance. A new working approach to quantify the degree of seed recalcitrance has been proposed in this paper. 展开更多
关键词 DESICCATION-TOLERANCE desiccation-sensitivity orthodox seed recalcitrant seed intermediate seed influence factor and assessment parameter of desiccation tolerance quantitative feature critical water content seed recalcitrance
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A Semi-Analytical Method for the PDFs of A Ship Rolling in Random Oblique Waves 被引量:2
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作者 LIU Li-qin LIU Ya-liu +2 位作者 XU Wan-hai LI Yan TANG You-gang 《China Ocean Engineering》 SCIE EI CSCD 2018年第1期74-84,共11页
The PDFs(probability density functions) and probability of a ship rolling under the random parametric and forced excitations were studied by a semi-analytical method. The rolling motion equation of the ship in random ... The PDFs(probability density functions) and probability of a ship rolling under the random parametric and forced excitations were studied by a semi-analytical method. The rolling motion equation of the ship in random oblique waves was established. The righting arm obtained by the numerical simulation was approximately fitted by an analytical function. The irregular waves were decomposed into two Gauss stationary random processes, and the CARMA(2, 1) model was used to fit the spectral density function of parametric and forced excitations. The stochastic energy envelope averaging method was used to solve the PDFs and the probability. The validity of the semi-analytical method was verified by the Monte Carlo method. The C11 ship was taken as an example, and the influences of the system parameters on the PDFs and probability were analyzed. The results show that the probability of ship rolling is affected by the characteristic wave height, wave length, and the heading angle. In order to provide proper advice for the ship’s manoeuvring, the parametric excitations should be considered appropriately when the ship navigates in the oblique seas. 展开更多
关键词 ship random rolling parametric and forced excitations stochastic energy envelope averaging method probability density function parameter influence analysis
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NOx storage and reduction assisted by non-thermal plasma over Co/Pt/Ba/γ-Al2O3 catalyst using CH_(4) as reductant 被引量:1
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作者 Tao ZHU Xing ZHANG +2 位作者 Nengjing YI Haibing LIU Zhenguo LI 《Plasma Science and Technology》 SCIE EI CAS CSCD 2021年第2期76-84,共9页
NOx storage and reduction(NSR)technology has been regarded as one of the most promising strategies for the removal of nitric oxides(NOx)from lean-burn engines,and the potential of the plasma catalysis method for NOx r... NOx storage and reduction(NSR)technology has been regarded as one of the most promising strategies for the removal of nitric oxides(NOx)from lean-burn engines,and the potential of the plasma catalysis method for NOx reduction has been confirmed in the past few decades.This work reports the NSR of nitric oxide(NO)by combining non-thermal plasma(NTP)and Co/Pt/Ba/γ-Al2O3(Co/PBA)catalyst using methane as a reductant.The experimental results reveal that the NOx conversion of NSR assisted by NTP is notably enhanced compared to the catalytic efficiency obtained from NSR in the range of 150°C–350°C,and NOx conversion of the 8%Co/PBA catalyst reaches 96.8%at 350°C.Oxygen(O_(2))has a significant effect on the removal of NOx,and the NOx conversion increases firstly and then decreases when the O_(2)concentration ranges from 2%to 10%.Water vapor reduces the NOx storage capacity of Co/PBA catalysts on account of the competition for adsorption sites on the surface of Co/PBA catalysts.There is a negative correlation between sulfur dioxide(SO_(2))and NOx conversion in the NTP system,and the 8%Co/PBA catalyst exhibits higher NOx conversion compared to other catalysts,which shows that Co has a certain SO_(2)resistance. 展开更多
关键词 non-thermal plasma NOx storage and reduction Co/Pt/Ba/γ-Al2O3 catalyst NOx conversion influence parameter
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Influence of modeling approaches and structural parameters on impact resistance of the human porous cranium
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作者 Qianqian Wu Jian Xiong 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2021年第6期910-928,I0001,共20页
Failure mechanism and impact resistance of a human porous cranium are studied in detail by means of theoretical and numerical methods.It is hypothesized that pore distribution of a cranium directly affects cranial ene... Failure mechanism and impact resistance of a human porous cranium are studied in detail by means of theoretical and numerical methods.It is hypothesized that pore distribution of a cranium directly affects cranial energy absorption,and a stretched beam model and a real beam model are taken as the example for the verification.Meanwhile,for the purpose of comparison with numerical results,a theoretical model is also proposed for the prediction of residual velocity and contact force of the impactor for an impacted skull.Compared with the real beam model,the stretched beam model containing through-thickness pores is easily deformed under the impact,thereby buffering well the external impact energy.The energy absorption efficiency of both the stretched beam model and real beam model is concerned with the threshold velocity for penetration which is directly related to the size of the structural damage area.Overall,there is good agreement between numerical and theoretical results.In addition,the effect of structural geometric parameters(shape and size of the impactor)on the impact resistance of the skull bone is theoretically investigated.The study provides reference for the evaluation of the energy absorption and failure mechanism of the skull under impact loads. 展开更多
关键词 Skull porous structure Impact resistance Modeling approach Theoretical prediction influence of structural parameters
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INFLUENCES OF NONSTATIONARY PROCESS ON INTERNAL PARAMETERS AND WIND PROFILES IN THE PLANETARY BOUNDARY LAYER
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作者 赵鸣 《Acta meteorologica Sinica》 SCIE 1989年第2期176-184,共9页
In this paper,under the assumption of neutral and barotropic atmosphere,by means of the analytic solution of motion equation of PBL,the influences of nonstationary process on the internal parameters u_*/A(A is the win... In this paper,under the assumption of neutral and barotropic atmosphere,by means of the analytic solution of motion equation of PBL,the influences of nonstationary process on the internal parameters u_*/A(A is the wind speed at the top of PBL)and ■(the angle between winds near the surface and at the top of PBL)of PBL are investigated in which the wind direction at the top of PBL is a periodic function of time but the wind speed at the top of PBL does not change.The u_*/A increases and ■ decreases when the wind direction at the top of PBL rotates anticlockwise and vice versa.Hence the parameterization of PBL in the large-scale models derived under the stationary condition should be corrected by accounting for the nonstationary process.The similar results are obtained in the numerical solution of the motion equation of PBL.The influences of this nonstationary process on the profiles of the wind in PBL are also analyzed. 展开更多
关键词 PBL influenceS OF NONSTATIONARY PROCESS ON INTERNAL parameters AND WIND PROFILES IN THE PLANETARY BOUNDARY LAYER
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Influence of the layer parameters on the performance of the CdTe solar cells
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作者 Assiya Haddout Abderrahim Raidou Mounir Fahoume 《Optoelectronics Letters》 EI 2018年第2期98-103,共6页
Influence of the layer parameters on the performances of the CdTe solar cells is analyzed by SCAPS-1 D. The Zn O: Al film shows a high efficiency than SnO_2:F. Moreover, the thinner window layer and lower defect densi... Influence of the layer parameters on the performances of the CdTe solar cells is analyzed by SCAPS-1 D. The Zn O: Al film shows a high efficiency than SnO_2:F. Moreover, the thinner window layer and lower defect density of Cd S films are the factor in the enhancement of the short-circuit current density. As well, to increase the open-circuit voltage, the responsible factors are low defect density of the absorbing layer CdTe and high metal work function. For the low cost of cell production, ultrathin film CdTe cells are used with a back surface field(BSF) between CdTe and back contact, such as PbTe. Further, the simulation results show that the conversion efficiency of 19.28% can be obtained for the cell with 1-μm-thick CdTe, 0.1-μm-thick PbTe and 30-nm-thick CdS. 展开更多
关键词 influence of the layer parameters on the performance of the CdTe solar cells
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Study of the second harmonic sound field from a circular piston source and the influence in the nonlinearity parameter tomography 被引量:1
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作者 ZHANG Dong CHEN Xi GONG Xiufen (State Key Lab . of Modern Acoustics, Institute of Acoustics, Nanjing University Nanjing 210093) 《Chinese Journal of Acoustics》 1999年第3期272-279,共8页
In the nonlinearity parameter B/A tomography using the second harmonic wav, it is very important to analyze the ultrasonic field of the transducer, especially the generation of the second harmonic wave in the near... In the nonlinearity parameter B/A tomography using the second harmonic wav, it is very important to analyze the ultrasonic field of the transducer, especially the generation of the second harmonic wave in the nearfield. In this paper, the theoretical study and experimental measurements of the second harmoinc pressure field from a circular piston source are performed.And the effect on the nonlinearity parameter tomograaphy is discussed. The results will be used to decrease the error of reconstruction in nonlinearity parameter tomography and bring the ultrasoinc diagnosis a step forward 展开更多
关键词 MHz Study of the second harmonic sound field from a circular piston source and the influence in the nonlinearity parameter tomography
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Study of the natural vibration characteristics of water motion in the moon pool by the semi-analytical method 被引量:3
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作者 刘利琴 李妍 +1 位作者 黄磊 唐友刚 《Journal of Hydrodynamics》 SCIE EI CSCD 2017年第1期124-134,共11页
The three-dimensional natural vibration characteristics of water inside a moon pool of an ocean structures are studied. The governing equations are derived based on the linear potential flow theory, and the boundary c... The three-dimensional natural vibration characteristics of water inside a moon pool of an ocean structures are studied. The governing equations are derived based on the linear potential flow theory, and the boundary condition of the total opening bottom suggested by Molin is adopted. A semi-analytical method is used to solve the governing equations, and the natural frequencies and the motion modes are obtained. Two types of motions are studied: (1) the piston motion in the vertical direction, and (2) the sloshing motion of the free surface. The influences of moon pool's structural parameters on the natural frequencies, and the modal shapes are analyzed. 展开更多
关键词 Moon pool natural vibration characteristics semi-analytical method parameter influences
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Parameter study on numerical simulation of corner separation in LMFA-NACA65 linear compressor cascade 被引量:2
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作者 Gao Feng Ma Wei +5 位作者 Sun Jinjing Jérome Boudet Xavier Ottavy Liu Yangwei Lu Lipeng Shao Liang 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2017年第1期15-30,共16页
Large-eddy simulation(LES) is compared with experiment and Reynolds-averaged Navier-Stokes(RANS), and LES is shown to be superior to RANS in reproducing corner separation in the LMFA-NACA65 linear compressor casca... Large-eddy simulation(LES) is compared with experiment and Reynolds-averaged Navier-Stokes(RANS), and LES is shown to be superior to RANS in reproducing corner separation in the LMFA-NACA65 linear compressor cascade, in terms of surface limiting streamlines,blade pressure coefficient, total pressure losses and blade suction side boundary layer profiles. However, LES is too expensive to conduct an influencing parameter study of the corner separation.RANS approach, despite over-predicting the corner separation, gives reasonable descriptions of the corner separated flow, and is thus selected to conduct a parametric study in this paper. Two kinds of influencing parameters on corner separation, numerical and physical parameters, are analyzed and discussed: second order spatial scheme is necessary for a RANS simulation; incidence angle and inflow boundary layer thickness are found to show the most significant influences on the corner separation among the parameters studied; unsteady RANS with the imposed inflow unsteadiness(inflow angle varying sinusoidally with fluctuating amplitude of 0.92°) does not show any non-linear effect on the corner separation. 展开更多
关键词 Corner separation Influencing parameter LES Linear compressor cascade RANS
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NUMERICAL INVESTIGATION OF INFLUENCING PARAMETER OF IMPERFECTIONS ON THIN SHORT CARBON STEEL CYLINDRICAL SHELL UNDER AXIAL COMPRESSION
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作者 B.PRABU 《International Journal of Modeling, Simulation, and Scientific Computing》 EI 2013年第3期12-29,共18页
Thin cylindrical shell structures have wide variety of applications due to their favorable stiffness-to-mass ratio and under axial compressive loading,these shell structures fail by their buckling instability.Hence,th... Thin cylindrical shell structures have wide variety of applications due to their favorable stiffness-to-mass ratio and under axial compressive loading,these shell structures fail by their buckling instability.Hence,their load carrying capacity is decided by its buckling strength which in turn predominantly depends on the geometrical imperfections present on the shell structure.The main aim of the present study is to determine the more influential geometrical parameter out of two geometrical imperfection parameters namely,“the extent of imperfection present over a surface area”and its“amplitude”.To account for these geometrical parameters simultaneously,the imperfection pattern is assumed as a dent having the shape of extent of surface area as a nearly square.The side length of extent of surface area can be considered as proportional to extent of imperfection present over an area and the dent depth can be considered as proportional to amplitude of imperfections.For the present numerical study,FE models of thin short carbon steel perfect cylindrical shells with different sizes of dent are generated at 1/3rd and half the height of cylindrical shells and analyzed using ANSYS nonlinear FE buckling analysis. 展开更多
关键词 Thin cylindrical shell buckling strength geometrical imperfections influencing parameter.
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