A theoretical model for calculating the stress and strain states of cabling structures with different loadings has been developed in this paper. We solve the problem for the first- and second-stage cable with tensile ...A theoretical model for calculating the stress and strain states of cabling structures with different loadings has been developed in this paper. We solve the problem for the first- and second-stage cable with tensile or bending strain. The contact and friction forces between the strands are presented by two-dimensional contact model. Several theoretical models have been proposed to verify the results when the triplet subjected to the tensile strain, including contact force, contact stresses, and mechanical loss. It is found that loadings will affect the friction force and the mechanical loss of the triplet. The results show that the contact force and mechanical loss are dependent on the twist pitch. A shorter twist pitch can lead to higher contact force, while the trend of mechanical loss with twist pitch is complicated. The mechanical loss may be reduced by adjusting the twist pitch reasonably. The present model provides a simple analysis method to investigate the mechanical behaviors in multistage-structures under different loads.展开更多
In this paper, the growth rate, ponderomotive force and the exciting condition for parametric instability are derived by considering the loss reaction using a new method. On the basis of the hydrodynamic equations, we...In this paper, the growth rate, ponderomotive force and the exciting condition for parametric instability are derived by considering the loss reaction using a new method. On the basis of the hydrodynamic equations, we take the production and loss reactions in plasma into account to derive the coupling equations for the electron plasma oscillation and ion acoustic oscillation, and obtain the growth rate for the parametric instability, the ponderomotive force and the exciting condition. The result shows that （a） the production reaction has no effect on the parametric instability, and the effect of loss reaction on the parametric instability is a damping one, （b） the more intensive the external field or pump is, the larger the growth rate is, （c） there exist two modes of the ponderomotive force, i.e. the high frequency mode and the low frequency mode, and （d） when ponderomotive force counteracts the damping force, the oscillations become non-damping and non-driving. The ratio of the electron plasma oscillation to ion acoustic oscillation is independent of the loss reaction and the external field.展开更多
The ?method is used in this paper to calculate the leakage magnetic field of SSZ11-50000/110 Power transformer, and by which the structures’ influences to the main leakage flux are analyzed. Through the combination o...The ?method is used in this paper to calculate the leakage magnetic field of SSZ11-50000/110 Power transformer, and by which the structures’ influences to the main leakage flux are analyzed. Through the combination of the product and TEAM Problem 21B, the surface impedance method shows its great advantage in the calculation of eddy current loss.展开更多
The loss of anchoring force is one of the problems to be solved urgently.The anchorage loss is a key factor causing the failure of anchoring engineering,so it is crucial to study the time-dependent variation of anchor...The loss of anchoring force is one of the problems to be solved urgently.The anchorage loss is a key factor causing the failure of anchoring engineering,so it is crucial to study the time-dependent variation of anchoring force.Alternating dry and wet(D-W)conditions have a significant effect on deformation of rock.The anchoring system is composed of anchoring components and rock mass,and thus rock deformation has a significant impact on the loss of anchoring force.Quantifying rock deformation under the effects of D-W cycles is a prerequisite to understanding the factors that influence loss of anchoring force in anchor bolts.In this study,we designed an anchoring device that enabled real-time monitoring of the variation in strain during D-W periods and rock testing.Nuclear magnetic resonance(NMR)measurements showed that under D-W conditions,the increment in porosity was smaller for prestressed rock than unstressed rock.The trends of prestress loss and strain variation are consistent,which can be divided into three characteristic intervals:rapid attenuation stage,slow attenuation stage and relatively stable stage.At the same stress level,the rate of stress loss and strain for the soaking specimen was the highest,while that of the dried specimen was the lowest.In the same D-W cycling conditions,the greater the prestress,the smaller the strain loss rate of the rock,especially under soaking conditions.The characteristics of pore structure and physical mechanical parameters indicated that prestress could effectively suppress damage caused by erosion related to D-W cycles.The study reveals the fluctuation behavior of rock strain and prestress loss under D-W conditions,providing a reference for effectively controlling anchoring loss and ideas for inventing new anchoring components.展开更多
根据EN12385-4:2002、ISO10425:2003中的公称金属截面系数,结合对Diepa、Casar、ArcelorMittal、OLIVEIRA等企业资料给出部分结构钢丝绳相关数据关系研究,探析GB/T 8706—2017中的计算最小破断拉力、最小破断拉力总和、计算最小破断拉...根据EN12385-4:2002、ISO10425:2003中的公称金属截面系数,结合对Diepa、Casar、ArcelorMittal、OLIVEIRA等企业资料给出部分结构钢丝绳相关数据关系研究,探析GB/T 8706—2017中的计算最小破断拉力、最小破断拉力总和、计算最小破断拉力总和、消减后的实测破断拉力总和、计算实测破断拉力、计算实测破断拉力总和与实测部分捻制损失系数等术语释义。基于对JIS G 3525:2013(JWPA/JSA)与JIS G 3546:2012(JWPA/JSA)给出钢丝绳破断拉力计算公式分析,认为将通常所称的捻制损失系数改称捻制损失剩余系数更合理。展开更多
In the flow on a mobile bed in an open channel, sand ripple often appears after the sediment begins to move. Different scholars have different views on the formation of sand ripples. This paper holds that as the rippl...In the flow on a mobile bed in an open channel, sand ripple often appears after the sediment begins to move. Different scholars have different views on the formation of sand ripples. This paper holds that as the ripple in general is very small, its formation is due to the instability of the laminar flow or the evolution of the small-scale coherent structures in the sublayer adjacent to the wall of the open channel. When the shear stresses caused by the disturbing waves or the coherent structure near the bed surface boundary and the water flow itself are greater than the shields stresses, responses on the bed surface appear and the sand ripple forms. If the frequency of the shear stress caused by the disturbance is close to the natural frequency of the sand grains that produced resonance, such a phenomenon is called the 'detection property' of the sediment. It is at this point that the maximum resonance appears and the sand ripple develops rapidly.展开更多
基金supported by National Natural Science Foundation of China (Grants 11202087, 11472120, 11421062)the National Key Project of Scientific Instrument and Equipment Development (Grant 11327802)+1 种基金the National Key Project of Magneto-Constrained Fusion Energy Development Program (Grant 2013GB110002)New Century Excellent Talents in University of Ministry of Education of China (Grant NCET-13-0266)
文摘A theoretical model for calculating the stress and strain states of cabling structures with different loadings has been developed in this paper. We solve the problem for the first- and second-stage cable with tensile or bending strain. The contact and friction forces between the strands are presented by two-dimensional contact model. Several theoretical models have been proposed to verify the results when the triplet subjected to the tensile strain, including contact force, contact stresses, and mechanical loss. It is found that loadings will affect the friction force and the mechanical loss of the triplet. The results show that the contact force and mechanical loss are dependent on the twist pitch. A shorter twist pitch can lead to higher contact force, while the trend of mechanical loss with twist pitch is complicated. The mechanical loss may be reduced by adjusting the twist pitch reasonably. The present model provides a simple analysis method to investigate the mechanical behaviors in multistage-structures under different loads.
基金Project supported by the National Natural Science Foundation of China （Grant No 40310223）, and the Fund of the National Key Laboratory of Electromagnetic Environment （Grant No 9140C080401060C0805）.
文摘In this paper, the growth rate, ponderomotive force and the exciting condition for parametric instability are derived by considering the loss reaction using a new method. On the basis of the hydrodynamic equations, we take the production and loss reactions in plasma into account to derive the coupling equations for the electron plasma oscillation and ion acoustic oscillation, and obtain the growth rate for the parametric instability, the ponderomotive force and the exciting condition. The result shows that （a） the production reaction has no effect on the parametric instability, and the effect of loss reaction on the parametric instability is a damping one, （b） the more intensive the external field or pump is, the larger the growth rate is, （c） there exist two modes of the ponderomotive force, i.e. the high frequency mode and the low frequency mode, and （d） when ponderomotive force counteracts the damping force, the oscillations become non-damping and non-driving. The ratio of the electron plasma oscillation to ion acoustic oscillation is independent of the loss reaction and the external field.
文摘The ?method is used in this paper to calculate the leakage magnetic field of SSZ11-50000/110 Power transformer, and by which the structures’ influences to the main leakage flux are analyzed. Through the combination of the product and TEAM Problem 21B, the surface impedance method shows its great advantage in the calculation of eddy current loss.
基金This work was supported by National Natural Science Foundation of China(Nos.52164001,52064006 and 52004072)the Science and Technology Support Project of Guizhou(Nos.[2020]4Y044),[2021]N404 and[2021]N511)+2 种基金the Cultivation Program of Guizhou University([2020]No.1)the Talents of Guizhou University(No.201901)the Special Research Funds of Guizhou University(Nos.201903,202011 and 202012).
文摘The loss of anchoring force is one of the problems to be solved urgently.The anchorage loss is a key factor causing the failure of anchoring engineering,so it is crucial to study the time-dependent variation of anchoring force.Alternating dry and wet(D-W)conditions have a significant effect on deformation of rock.The anchoring system is composed of anchoring components and rock mass,and thus rock deformation has a significant impact on the loss of anchoring force.Quantifying rock deformation under the effects of D-W cycles is a prerequisite to understanding the factors that influence loss of anchoring force in anchor bolts.In this study,we designed an anchoring device that enabled real-time monitoring of the variation in strain during D-W periods and rock testing.Nuclear magnetic resonance(NMR)measurements showed that under D-W conditions,the increment in porosity was smaller for prestressed rock than unstressed rock.The trends of prestress loss and strain variation are consistent,which can be divided into three characteristic intervals:rapid attenuation stage,slow attenuation stage and relatively stable stage.At the same stress level,the rate of stress loss and strain for the soaking specimen was the highest,while that of the dried specimen was the lowest.In the same D-W cycling conditions,the greater the prestress,the smaller the strain loss rate of the rock,especially under soaking conditions.The characteristics of pore structure and physical mechanical parameters indicated that prestress could effectively suppress damage caused by erosion related to D-W cycles.The study reveals the fluctuation behavior of rock strain and prestress loss under D-W conditions,providing a reference for effectively controlling anchoring loss and ideas for inventing new anchoring components.
文摘根据EN12385-4:2002、ISO10425:2003中的公称金属截面系数,结合对Diepa、Casar、ArcelorMittal、OLIVEIRA等企业资料给出部分结构钢丝绳相关数据关系研究,探析GB/T 8706—2017中的计算最小破断拉力、最小破断拉力总和、计算最小破断拉力总和、消减后的实测破断拉力总和、计算实测破断拉力、计算实测破断拉力总和与实测部分捻制损失系数等术语释义。基于对JIS G 3525:2013(JWPA/JSA)与JIS G 3546:2012(JWPA/JSA)给出钢丝绳破断拉力计算公式分析,认为将通常所称的捻制损失系数改称捻制损失剩余系数更合理。
文摘In the flow on a mobile bed in an open channel, sand ripple often appears after the sediment begins to move. Different scholars have different views on the formation of sand ripples. This paper holds that as the ripple in general is very small, its formation is due to the instability of the laminar flow or the evolution of the small-scale coherent structures in the sublayer adjacent to the wall of the open channel. When the shear stresses caused by the disturbing waves or the coherent structure near the bed surface boundary and the water flow itself are greater than the shields stresses, responses on the bed surface appear and the sand ripple forms. If the frequency of the shear stress caused by the disturbance is close to the natural frequency of the sand grains that produced resonance, such a phenomenon is called the 'detection property' of the sediment. It is at this point that the maximum resonance appears and the sand ripple develops rapidly.
