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Electric field and force characteristic of dust aerosol particles on the surface of high-voltage transmission line
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作者 刘滢格 李兴财 +2 位作者 王娟 马鑫 孙文海 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第1期368-378,共11页
High-voltage transmission lines play a crucial role in facilitating the utilization of renewable energy in regions prone to desertification. The accumulation of atmospheric particles on the surface of these lines can ... High-voltage transmission lines play a crucial role in facilitating the utilization of renewable energy in regions prone to desertification. The accumulation of atmospheric particles on the surface of these lines can significantly impact corona discharge and wind-induced conductor displacement. Accurately quantifying the force exerted by particles adhering to conductor surfaces is essential for evaluating fouling conditions and making informed decisions. Therefore, this study investigates the changes in electric field intensity along branched conductors caused by various fouling layers and their resulting influence on the adhesion of dust particles. The findings indicate that as individual particle size increases, the field strength at the top of the particle gradually decreases and eventually stabilizes at approximately 49.22 k V/cm, which corresponds to a field strength approximately 1.96 times higher than that of an unpolluted transmission line. Furthermore,when particle spacing exceeds 15 times the particle size, the field strength around the transmission line gradually decreases and approaches the level observed on non-adhering surface. The electric field remains relatively stable. In a triangular arrangement of three particles, the maximum field strength at the tip of the fouling layer is approximately 1.44 times higher than that of double particles and 1.5 times higher compared to single particles. These results suggest that particles adhering to the transmission line have a greater affinity for adsorbing charged particles. Additionally, relevant numerical calculations demonstrate that in dry environments, the primary adhesion forces between particles and transmission lines follow an order of electrostatic force and van der Waals force. Specifically, at the minimum field strength, these forces are approximately74.73 times and 19.43 times stronger than the gravitational force acting on the particles. 展开更多
关键词 high-voltage current electric field aerosol particles force characteristic
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FLOW PATTERNS AND FORCE CHARACTERISTICS OF LAMINAR FLOW PAST FOUR CYLINDERS IN DIAMOND ARRANGEMENT 被引量:13
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作者 ZOU Lin LIN Yu-feng LU Hong 《Journal of Hydrodynamics》 SCIE EI CSCD 2011年第1期55-64,共10页
A three-dimensional numerical investigation of cross-flow past four circular cylinders in a diamond arrangement at Reynolds number of 200 is carried out.With the spacing ratios(L /D)ranging from 1.2 to 5.0,the flow ... A three-dimensional numerical investigation of cross-flow past four circular cylinders in a diamond arrangement at Reynolds number of 200 is carried out.With the spacing ratios(L /D)ranging from 1.2 to 5.0,the flow patterns can be classified into three basic regimes.The critical spacing ratio for the transition from narrow gap flow pattern to vortex impingement flow pattern around the cylinders is found to beL /D=3.0,while a single bluff-body flow pattern is observed atL /D=1.2.The relationship between the three-dimensional flow patterns and force characteristics around the four cylinders shows that the variation of forces and Strouhal numbers againstL /D are generally governed by these three kinds of flow patterns.It is concluded that the spacing ratio has important effects on the development of the free shear layers about the cylinders and hence has significant effects on the force and pressure characteristics of the four cylinders with different spacing ratios. 展开更多
关键词 four cylinders spacing ratio flow pattern force characteristics
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Study on excitation force characteristics in a coupled shaker-structure system considering structure modes coupling 被引量:1
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作者 Guiwei ZHANG Xiaochen WANG Zhichun YANG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2022年第7期227-245,共19页
The interaction between an elastic structure and electrodynamic shakers commonly exists in Ground Flutter Simulation Tests(GFST)with multi-point excitations,causing a considerable discrepancy between the practical exc... The interaction between an elastic structure and electrodynamic shakers commonly exists in Ground Flutter Simulation Tests(GFST)with multi-point excitations,causing a considerable discrepancy between the practical excitation forces and desired ones.To investigate the excitation force characteristics on a cantilever beam excited by a voltage-sourced electrodynamic shaker,the coupled shaker-beam system is modeled to derive the excitation force formula using Hamilton’s principle and Galerkin’s approach.Simulation results using the multi-mode beam model coupled with the shaker model are in good agreement with experimental results,verifying that the proposed multi-mode method can accurately predict the excitation force.Furthermore,parametric studies show that the influence of system parameters on the excitation force is related to the shaker’s operating mode.Unlike in current mode of shaker,when the beam resonant frequency approaches the suspension frequency of shaker armature,the variation of excitation force amplitude in voltage mode is no longer minimal.Meanwhile,if the exciting point in the GFST is located far away from the modal node,it is essential to compensate the force because the accuracy of tests can be reduced dramatically.The coupled shaker-beam model proposed in this paper can provide the basis for compensation measures. 展开更多
关键词 Electrodynamic shaker force characteristics Galerkin’s approach Lumped parameter model Parameters estimation
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Cutting Characteristics of Force Controllable Milling Head
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作者 Shirakashi Takahiro Shibuya Wataru 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第S1期108-,共1页
In order to control cutting force and its direction i n milling operation, a new milling head was developed. The head has two milling cutters, which are connected by a pair of gears and rotate in opposite direction re... In order to control cutting force and its direction i n milling operation, a new milling head was developed. The head has two milling cutters, which are connected by a pair of gears and rotate in opposite direction respectively. Both up-cut and down-cut can be carried out simultaneously by t hese milling cutters. The each depth of cut, the ratio of up/down cutting depth , by these cutters can be also selected. The cutting force characteristics were experimentally discussed by changing the ratio. The cutting force and its locus can be also changed by the selection of the ratio of up/down cutting depth. For practical usage of the head the analytical prediction method of the cutting forc e characteristics under selected cutting condition was proposed based on the ene rgy approach method proposed, in which both of cutting force characteristics of a single milling cutter and the combined milling cutter under a selected up/dow n cutting depth ratio were analytically estimated based on the two dimensional c utting data. It was experimentally shown that in NC milling machine the cutting force locus was controlled in pre-determined direction under various tool paths . 展开更多
关键词 Cutting characteristics of force Controllable Milling Head
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Evidence of earthquakes triggered by the tidal force of the sun and the moon——On the temporal characteristics of the earthquakes in Xingtai,Hejian and Tangshan
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作者 黎凯武 《Acta Seismologica Sinica(English Edition)》 EI CSCD 1998年第5期116-123,共8页
Studies by many scientists show that Hebei, China is an area with strong correlation between the tidal force and the occurrences of major earthquakes, the Xingtai earthquake of 1966, the Hejian earthquake of 1967 and ... Studies by many scientists show that Hebei, China is an area with strong correlation between the tidal force and the occurrences of major earthquakes, the Xingtai earthquake of 1966, the Hejian earthquake of 1967 and the Tangshan earthquake of 1976 were triggered by the tidal force, in this paper the study on the common characteristics of their occurrence times confirms these facts. The computed times of maximum horizontal of the semi diurnal solid tide tidal force show that the occurrence times of the above mentioned earthquakes were close to the times of maximum horizontal tidal force of the semi diurnal solid tide at new moon or full moon. The Longyao earthquake of M =6.8, the Ningjin earthquake of M =7.2 and the Hejian earthquake of M =6.3 occurred tens of minutes after the maximum horizontal tidal force of the semi diurnal solid tides, and the Tangshan earthquake of M =7.8 occurred 16 minutes before the maximum horizontal tidal force. The tidal forces were directed to the west. This is their temporal characteristic. It is generally accepted that the 1969 Bohai earthquake of M =7.4 and the 1975 Haicheng earthquake were not triggered by the tidal force. These events did not show such characteristics. The temporal characteristics of the earthquakes indicate that the occurrences of these events were not random, but were controlled by the tidal force from the sun and the moon, and triggered by the tidal force. These facts agree with the triggering mechanism of the tidal force, are evidences of earthquakes triggered by tidal force. 展开更多
关键词 horizontal tidal force\ triggered earthquake\ temporal characteristics\ triggering mechanism
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Introducing driving-force information increases the predictability of the North Atlantic Oscillation
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作者 PAN Xinnong WANG Geli YANG Peicai 《Atmospheric and Oceanic Science Letters》 CSCD 2019年第5期329-336,共8页
The North Atlantic Oscillation(NAO)is the most prominent mode of atmospheric variability in the Northern Hemisphere.Because of the close relationship between the NAO and regional climate in Eurasia,North Atlantic,and ... The North Atlantic Oscillation(NAO)is the most prominent mode of atmospheric variability in the Northern Hemisphere.Because of the close relationship between the NAO and regional climate in Eurasia,North Atlantic,and North America,improving the prediction skill for the NAO has attracted much attention.Previous studies that focused on the predictability of the NAO were often based upon simulations by climate models.In this study,the authors took advantage of Slow Feature Analysis to extract information on the driving forces from daily NAO index and introduced it into phase-space reconstruction.By computing the largest Lyapunov exponent,the authors found that the predictability of daily NAO index shows a significant increase when its driving force signal is considered.Furthermore,the authors conducted a short-term prediction for the NAO by using a global prediction model for chaotic time series that incorporated the driving-force information.Results showed that the prediction skill for the NAO can be largely increased.In addition,results from wavelet analysis suggested that the driving-force signal of the NAO is associated with three basic drivers:the annual cycle(1.02 yr),the quasi-biennial oscillation(QBO)(2.44 yr);and the solar cycle(11.6 yr),which indicates the critical roles of the QBO and solar activities in the predictability of the NAO. 展开更多
关键词 North Atlantic Oscillation slow feature analysis driving force characteristics time series prediction
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Experimental study on characteristic curves of restoring forces of Populus alba var. pyramidalis 被引量:1
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作者 ZHOU Jian-zhong 《Forestry Studies in China》 CAS 2011年第4期315-320,共6页
Static tests under cyclic loading were carried out on Populus alba var. pyramidalis to determine its characteristic curves of restoring forces. The results show that P alba var. pyramidalis had good elastic performanc... Static tests under cyclic loading were carried out on Populus alba var. pyramidalis to determine its characteristic curves of restoring forces. The results show that P alba var. pyramidalis had good elastic performance. There was degradation of strength and stiffness under cyclic loading and unloading, where characteristic curves of restoring forces ofP. alba var. pyrarnidalis assumed a "flat and contrary S-shape" form. Simultaneously, P alba vat. pyramidalis showed typical characteristics of brittle destruction under large high peak loading and unloading. Furthermore, dynamic tests were carried out under wind loads to obtain dynamic displacement curves and dynamic strain curves. P alba var. pyramidalis reflected its stochastic dynamic performance in building up its resistance to the stochastic wind loads and its dynamically hysteretic properties. The dynamic response of this species was random and fuzzy under stochastic wind loads. This study has theoretical significance and reference value to research on the static characteristics and wind-induced dynamic performance of forests. 展开更多
关键词 Populus alba var. pyramidalis characteristic curve of restoring forces degradation of strength and stiffness stochasticwind loads
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Turbulent forced convection in a heat exchanger square channel with wavy-ribs vortex generator
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作者 Amnart Boonloi Withada Jedsadaratanachai 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第8期1256-1265,共10页
Turbulent forced convective heat transfer and flow con figurations in a square channel with wavy-ribs inserted diagonally are examined numerically. The in fluences of the 30° and 45° flow attack angles for w... Turbulent forced convective heat transfer and flow con figurations in a square channel with wavy-ribs inserted diagonally are examined numerically. The in fluences of the 30° and 45° flow attack angles for wavy-ribs, blockage ratio, R B= b/H = 0.05–0.25 with single pitch ratio, R P= P/H = 1 are investigated for the Reynolds number based on the hydraulic diameter of the square channel, Re = 3000–20000. The use of the wavy-ribs, which inserted diagonal in the square channel, is aimed to help to improve the thermal performance in heat exchange systems.The finite volume method and SIMPLE algorithm are applied to the present numerical simulation. The results are presented on the periodic flow and heat transfer pro files, flow con figurations, heat transfer characteristics and the performance evaluations. The mathematical results reveal that the use of wavy-ribs leads to a higher heat transfer rate and friction loss over the smooth channel. The heat transfer enhancements are around 1.97–5.14 and 2.04–5.27 times over the smooth channel for 30° and 45° attack angles, respectively. However, the corresponding friction loss values for 30° and 45° are around 4.26–86.55 and 5.03–97.98 times higher than the smooth square channel, respectively. The optimum thermal enhancement factor on both cases is found at R B= 0.10 and the lowest Reynolds number, Re = 3000, to be about 1.47 and 1.52, respectively, for 30° and 45° wavy-ribs. 展开更多
关键词 Flow configuration forced convection Heat transfer characteristic Turbulent flow Wavy-ribs
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Design and Analysis of a Novel Compliant Mechanism with RPR Degrees of Freedom 被引量:1
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作者 Shuang Zhang Jingfang Liu Huafeng Ding 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2022年第5期262-274,共13页
A novel compliant mechanism with RPR degrees of freedom(DOF)is proposed where R and P represent rotation and translation DOFs,respectively.The proposed compliant mechanism is obtained from dimension synthesizing a 2-R... A novel compliant mechanism with RPR degrees of freedom(DOF)is proposed where R and P represent rotation and translation DOFs,respectively.The proposed compliant mechanism is obtained from dimension synthesizing a 2-RPU-UPR rigid parallel mechanism with the method of optimization of motion/force transfer characteristic.R,P and U represent rotation,translation and universal pairs,respectively.Firstly,inverse kinematics and Jacobian matrix are analyzed for the dimensional synthesis.Then,output transmission indexes of branches in the parallel mechanism are given.Dimensional synthesis is completed based on the normalized design parameter.And optimization of flexure joints based on constrained energy is carried out.Afterwards,the novel compliant mechanism is obtained by direct replacing method.Mechanical model of the compliant mechanism including static stiffness and input stiffness is built based on the pseudo-rigid body modeling method and virtual work principle.Finally,FEA simulation by Ansys Workbench is carried out to verify DOF,effectiveness of the dimension synthesis,and compliant model.Optimization of motion/force transfer characteristic is first applied for the design of compliant mechanisms to suppress drift of rotation axis in the paper. 展开更多
关键词 Compliant mechanism RPR degrees of freedom Motion/force transfer characteristic Mechanical model OPTIMIZATION
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A Survey of Development and Features of Ganzhou Orange Industrial Clusters in China
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作者 Shanqing Liu Xiaolan Ye Wenhua Chen 《Chinese Business Review》 2006年第5期63-65,共3页
Ganzhou Orange Industrial Clusters (GOIC for short) is mainly characterized as follows. (1)The Government's driving force is the key factor for the formation and development of GOIC; (2)the interaction between ... Ganzhou Orange Industrial Clusters (GOIC for short) is mainly characterized as follows. (1)The Government's driving force is the key factor for the formation and development of GOIC; (2)the interaction between market and industry; (3)the specific geography and natural resources act as a carrier; (4)with a strong sense of innovation; (5)it is still at the early stage of development, with a certain high cost. 展开更多
关键词 Ganzhou Orange characteristic industrial cluster government's driving force
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EXPERIMENTAL AND NUMERICAL STUDY FOR HYDRODYNAMIC CHARACTERISTICS OF AN OSCILLATING HYDROFOIL 被引量:13
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作者 LIU Zhen HYUN Bcom-soo +1 位作者 KIM Moo-rong JIN Ji-yuan 《Journal of Hydrodynamics》 SCIE EI CSCD 2008年第3期280-287,共8页
The present article reports the experimental Particle Image Velocimetry (PIV) investigation and the corresponding numerical simulation results about the water flow over the oscillating hydrofoil and its unsteady dyn... The present article reports the experimental Particle Image Velocimetry (PIV) investigation and the corresponding numerical simulation results about the water flow over the oscillating hydrofoil and its unsteady dynamic characters. The experimental study focuses on the effect of mean angles of attack. The comparison between the PIV results and numerical prediction about the flow field using Fluent well demonstrates the capability of CFD on the simulation of the water flow around the pitching hydrofoil. The numerical results indicate that the forced oscillating frequencies have evident effects on the flow separation and vortex shedding. The simulations about the hydrodynamic drag and lift coefficients were also performed. 展开更多
关键词 Particle Image Velocimetry (PIV) oscillating hydrofoil numerical simulation FLUENT flow field force characteristics
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Study on Force Mechanism for Therapeutic Effect of Pushing Manipulation with One-Finger Meditation Base on Similarity Analysis of Force and Waveform 被引量:4
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作者 FANG Lei FANG Min GUO Min-min 《Chinese Journal of Integrative Medicine》 SCIE CAS CSCD 2018年第7期531-536,共6页
Objective: To reveal the force mechanism for therapeutic effect of pushing manipulation with one-finger meditation. Methods: A total of 15 participants were recruited in this study and assigned to an expert group, a... Objective: To reveal the force mechanism for therapeutic effect of pushing manipulation with one-finger meditation. Methods: A total of 15 participants were recruited in this study and assigned to an expert group, a skilled group and a novice group, with 5 participants in each group. Mechanical signals were collected from a biomechanical testing platform, and these data were further observed via similarity analysis and cluster analysis. Results: Comparing the force waveforms of manipulation revealed that the manipulation forces were similar between the expert group and the skilled group(P〉0.05). The mean value of vertical force was 9.8 N, and 95% CI rang from 6.37 to 14.70 N, but there were significant differences compared with the novice group(P〈0.05). The result of overall similarity coefficient cluster analysis showed that two kinds of manipulation forces curves were existed between the expert group and the skilled group. Conclusion: Pushing manipulation with one-finger meditation is a kind of light stimulation manipulation on the acupoint, and force characteristics of double waveforms continuously alternated during manual operation. 展开更多
关键词 pushing manipulation with one-finger meditation Tuina biomechanics force characteristics WAVEFORM
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