There was a slow-relaxing tail of skeletal muscles in vitro upon the inhibition of Ca2+-pump by cyclopiazonic acid (CPA). Herein, a new linearly-combined bi-exponential model to resolve this slow-relaxing tail from th...There was a slow-relaxing tail of skeletal muscles in vitro upon the inhibition of Ca2+-pump by cyclopiazonic acid (CPA). Herein, a new linearly-combined bi-exponential model to resolve this slow-relaxing tail from the fast-relaxing phase was investigated for kinetic analysis of the isometric relaxation process of Bufo gastrocnemius in vitro, in comparison to the single exponential model and the classical bi-exponential model. During repetitive stimulations at a 2-s interval by square pulses of a 2-ms duration at 12 V direct currency (DC), the isometric tension of Bufo gastrocnemius was recorded at 100 Hz. The relaxation curve with tensions falling from 90% of the peak to the 15th datum before next stimulation was analyzed by three exponential models using a program in MATLAB 6.5. Both the goodness of fit and the distribution of the residuals for the best fitting sup- ported the comparable validity of this new bi-exponential model for kinetic analysis of the relaxation process of the control muscles. After CPA treatment, however, this new bi-exponential model showed an obvious statistical superiority for kinetic analysis of the muscle relaxation process, and it gave the estimated rest tension consistent to that by experimentation, whereas both the classical bi-exponential model and the single exponential model gave biased rest tensions. Moreover, after the treatment of muscles by CPA, both the single exponential model and the classical bi-exponential model yielded lowered relaxation rates, nevertheless, this new bi-exponential model had relaxation rates of negligible changes except much higher rest tensions. These results suggest that this novel linearly-combined bi-exponential model is desirable for kinetic analysis of the relaxation process of muscles with altered Ca2+-pumping activity.展开更多
The load transfer characteristics of a tensile anchor in the rock mass with weak interlayers were investigated,considering the nonuniform stress of the horizontally layered rock mass along anchors.An improved shear-sl...The load transfer characteristics of a tensile anchor in the rock mass with weak interlayers were investigated,considering the nonuniform stress of the horizontally layered rock mass along anchors.An improved shear-slipping model was proposed to describe the stress evolution characteristics of the bolt-rock interface.Based on the improved model,analytical solutions of the axial force,shear stress distribution and load-displacement relationship considering the residual stress stage were established.The effects of the stratigraphic sequence,pulling force and bolt diameter on the stress distribution of the anchorage interface were evaluated by using analytical solutions.The results were verified by applying the finite difference numerical simulation method.The sensitivity of each parameter to the axial force and shear stress of the rock bolt was determined based on calculation of the sensitivity coefficient.The study results show that the axial force and shear stress tend to decrease nonuniformly along the rock bolt towards the anchorage depth.Due to the existence of weak interlayers,the shear stress mutates at the weak and hard rock interface,and the axial force appears to“rebound”at the bottom of the anchored section.Lithology has more significant effects on the axial force and shear stress at the bottom of the anchor than at the top of the anchor.The pulling force is more sensitive to the anchor stress than stratigraphic sequence when the bolt diameter is determined.This study provides a theoretical framework for the fundamental problem of tensile bolts in horizontally or vertically laminated rock masses,providing a theoretical basis for anchor design.展开更多
Electric towers of high voltage transmission lines are more exposed to natural lightning phenomena thanks to their high heights. These lines are crossed by powerful current sources to dissipate in the ground, which ca...Electric towers of high voltage transmission lines are more exposed to natural lightning phenomena thanks to their high heights. These lines are crossed by powerful current sources to dissipate in the ground, which can, at one time or another, create disturbances or other phenomena can be generated. This is why we have set ourselves the objective of studying the FDTD modeling of the influence of direct lightning strikes on the power transmitted by a High-Voltage power line. To do this, we have implemented Kirchhoff’s laws to model the power transmitted by a High-Voltage power line in a steady state. Calculating the electromagnetic field generated by lightning requires the lightning current along the channel and its spatiotemporal distribution, the bi-exponential models and that of engineers were chosen and used to reproduce the physical phenomena best. Several works have been published in the literature and various mathematical models are proposed, to study the filamentous nature of power lines which has led to a more flexible modelling, based on the transmission line model, associated with the field theory developed from Maxwell’s equations, which explain the interaction between a lightning wave and a power transmission line. The resolution of the line equations in the lightning shock regime was the subject of the FDTD method to obtain the results in the spatio-temporal domain. Through this research, we are interested in the study of the spatiotemporal distribution of the lightning current wave to model the radiated electromagnetic field and to examine the influence of the overvoltage induced by the atmospheric discharge on the transportable power of a High Voltage AC Transmission line, for good selective protection to illuminate the parasites. 2D simulations based on proposed models were developed as well as the verification of the consistency of the different models, by comparing the fractal dimensions of the results of our program with those of the figures obtained experimentally. The aspects developed in this article could have direct implications in practical applications in the engineering and design of high-voltage transmission systems.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 30472139)the Education Commission for the First Batch of Excellent Young Teachers in Universities of Chongqing City, China
文摘There was a slow-relaxing tail of skeletal muscles in vitro upon the inhibition of Ca2+-pump by cyclopiazonic acid (CPA). Herein, a new linearly-combined bi-exponential model to resolve this slow-relaxing tail from the fast-relaxing phase was investigated for kinetic analysis of the isometric relaxation process of Bufo gastrocnemius in vitro, in comparison to the single exponential model and the classical bi-exponential model. During repetitive stimulations at a 2-s interval by square pulses of a 2-ms duration at 12 V direct currency (DC), the isometric tension of Bufo gastrocnemius was recorded at 100 Hz. The relaxation curve with tensions falling from 90% of the peak to the 15th datum before next stimulation was analyzed by three exponential models using a program in MATLAB 6.5. Both the goodness of fit and the distribution of the residuals for the best fitting sup- ported the comparable validity of this new bi-exponential model for kinetic analysis of the relaxation process of the control muscles. After CPA treatment, however, this new bi-exponential model showed an obvious statistical superiority for kinetic analysis of the muscle relaxation process, and it gave the estimated rest tension consistent to that by experimentation, whereas both the classical bi-exponential model and the single exponential model gave biased rest tensions. Moreover, after the treatment of muscles by CPA, both the single exponential model and the classical bi-exponential model yielded lowered relaxation rates, nevertheless, this new bi-exponential model had relaxation rates of negligible changes except much higher rest tensions. These results suggest that this novel linearly-combined bi-exponential model is desirable for kinetic analysis of the relaxation process of muscles with altered Ca2+-pumping activity.
基金supported by the National Key R&D Program of China(Nos.2018YFC1505300,2017YFC1501304)National Natural Science Foundation of China(Grout Nos.42090054,41922055 and 41931295)+2 种基金the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(No.CUGGC09)Research Project of China Three Gorges Corporation(No.2019073)the Zhejiang Huadong Construction Engineering Co.,Ltd.(No.KY2019-HDJS-07)。
文摘The load transfer characteristics of a tensile anchor in the rock mass with weak interlayers were investigated,considering the nonuniform stress of the horizontally layered rock mass along anchors.An improved shear-slipping model was proposed to describe the stress evolution characteristics of the bolt-rock interface.Based on the improved model,analytical solutions of the axial force,shear stress distribution and load-displacement relationship considering the residual stress stage were established.The effects of the stratigraphic sequence,pulling force and bolt diameter on the stress distribution of the anchorage interface were evaluated by using analytical solutions.The results were verified by applying the finite difference numerical simulation method.The sensitivity of each parameter to the axial force and shear stress of the rock bolt was determined based on calculation of the sensitivity coefficient.The study results show that the axial force and shear stress tend to decrease nonuniformly along the rock bolt towards the anchorage depth.Due to the existence of weak interlayers,the shear stress mutates at the weak and hard rock interface,and the axial force appears to“rebound”at the bottom of the anchored section.Lithology has more significant effects on the axial force and shear stress at the bottom of the anchor than at the top of the anchor.The pulling force is more sensitive to the anchor stress than stratigraphic sequence when the bolt diameter is determined.This study provides a theoretical framework for the fundamental problem of tensile bolts in horizontally or vertically laminated rock masses,providing a theoretical basis for anchor design.
文摘Electric towers of high voltage transmission lines are more exposed to natural lightning phenomena thanks to their high heights. These lines are crossed by powerful current sources to dissipate in the ground, which can, at one time or another, create disturbances or other phenomena can be generated. This is why we have set ourselves the objective of studying the FDTD modeling of the influence of direct lightning strikes on the power transmitted by a High-Voltage power line. To do this, we have implemented Kirchhoff’s laws to model the power transmitted by a High-Voltage power line in a steady state. Calculating the electromagnetic field generated by lightning requires the lightning current along the channel and its spatiotemporal distribution, the bi-exponential models and that of engineers were chosen and used to reproduce the physical phenomena best. Several works have been published in the literature and various mathematical models are proposed, to study the filamentous nature of power lines which has led to a more flexible modelling, based on the transmission line model, associated with the field theory developed from Maxwell’s equations, which explain the interaction between a lightning wave and a power transmission line. The resolution of the line equations in the lightning shock regime was the subject of the FDTD method to obtain the results in the spatio-temporal domain. Through this research, we are interested in the study of the spatiotemporal distribution of the lightning current wave to model the radiated electromagnetic field and to examine the influence of the overvoltage induced by the atmospheric discharge on the transportable power of a High Voltage AC Transmission line, for good selective protection to illuminate the parasites. 2D simulations based on proposed models were developed as well as the verification of the consistency of the different models, by comparing the fractal dimensions of the results of our program with those of the figures obtained experimentally. The aspects developed in this article could have direct implications in practical applications in the engineering and design of high-voltage transmission systems.
