A size-dependent continuum-based model is developed for the functionally graded(FG)Timoshenko micro-beams with viscoelastic properties,in which material parameters vary according to the power law along its axial direc...A size-dependent continuum-based model is developed for the functionally graded(FG)Timoshenko micro-beams with viscoelastic properties,in which material parameters vary according to the power law along its axial direction.The size effect is incorporated by employing the modified couple stress theory and Kelvin-Voigt viscoelastic model,so that viscous components are included in the stress and the deviatoric segments of the symmetric couple stress tensors.The components of strain,curvature,stress and couple stress are formulated by combining them with the Timoshenko beam theory.Based on the Hamilton principle,the governing differential equations and boundary conditions for the micro-beam are expressed with arbitrary beam section shape and arbitrary type of loads.The size effect,FG effect,Poisson effect,and the influence of the beam section shape on the mechanical behaviors of viscoelastic FG micro-beams are investigated by taking the simply supported micro-beam subjected to point load as an example.Results show that the size effect on deflection,normal stress and couple stress are obvious when the size of the micro-beam is small enough,and the FG effects are obvious when the size of the micro-beam is large enough.Moreover,the Poisson ratio influences the size effect significantly and the beam section shape is also an important factor influencing the mechanical behavior of the micro-beam.展开更多
Insulation failures of epoxy spacers applied in gas insulated transmission line/switchgear(GIL/GIS)often occur,primarily due to electric field distortion.In this paper,a field graded coating CaCu_(3)Ti_(4)O_(12)(CCTO)...Insulation failures of epoxy spacers applied in gas insulated transmission line/switchgear(GIL/GIS)often occur,primarily due to electric field distortion.In this paper,a field graded coating CaCu_(3)Ti_(4)O_(12)(CCTO)is presented to enhance the flashover performance of a GIL/GIS spacer.First,CCTO layers of different thicknesses are deposited on the spacer surface using magnetron sputtering technology.Then,insulating properties of these sputtered spacers under alternating current,direct current,and polarity reversal(PR)voltages and with the existence of metal particles are researched by experimental and simulation methods.Results show the short-term(30 and 60 min)sputtering treatments have no obvious effect on improving insulating properties.展开更多
This work focus on the mechanical behaviors,which are related to the size effect,functionally graded(FG)effect and Poisson effect,of an axially functionally graded(AFG)micro-beam whose elastic modulus varies according...This work focus on the mechanical behaviors,which are related to the size effect,functionally graded(FG)effect and Poisson effect,of an axially functionally graded(AFG)micro-beam whose elastic modulus varies according to sinusoidal law along its axial direction.The displacement field of the AFG micro-beam is set according to the Bernoulli-Euler beam theory.Employing the modified couple stress theory(MCST),the components of strain,curvature,stress and couple stress are expressed by the second derivative of the deflection of the AFG micro-beam.A size-dependent model related to FG effect and Poisson effect,which includes the formulations of bending stiffness,deflection,normal stress and couple stress,is developed to predict the mechanical behaviors of the AFG microbeam by employing the principle of minimum potential energy.The mechanical behaviors of a simply supported AFG micro-beam are numerically investigated using the developed model for demonstrating the size effects,FG effects and Poisson effects of the AFG micro-beam.Results show that the mechanical behaviors of AFG micro-beams are distinctly size-dependent only when the ratio of micro-beam height to material length-scale parameter is small enough.The FG parameter is an important factor that determines and regulates the size-dependent behaviors of AFG micro-beams.The influences of Poisson’s ratio on the mechanical behaviors of AFG micro-beams are not negligible,and should be also considered in the design and analysis of an AFG micro-beam.This work supplies a theoretical basis and a technical reference for the design and analysis of AFG micro-beams in the related regions.展开更多
Objective: to explore the role and effect of rescue nursing intervention in emergency patients with organophosphorus pesticide poisoning. Methods: according to the random drawing method, 80 patients with organophospho...Objective: to explore the role and effect of rescue nursing intervention in emergency patients with organophosphorus pesticide poisoning. Methods: according to the random drawing method, 80 patients with organophosphorus and organophosphorus pesticide poisoning admitted to our hospital from May 2020 to April 2021 were selected and divided into analysis group and control group, which received interventional treatment and rescue treatment respectively. The intervention was carried out by conventional nursing methods in this group, and the nursing satisfaction rate of patients was compared with the rescue nursing effect of the control group and the analysis group. Results: the nursing satisfaction rate of patients in the analysis group who received rescue related treatment was significantly higher than that in the control group who received routine nursing measures, while the rescue treatment score of patients in the control group was significantly lower than the effectiveness score. There was clinical correlation between the two groups (P < 0.05). The incidence of adverse reactions in the analysis group was better than that in the control group, and the difference between the two groups was clinically comparable (P < 0.05). Conclusion: gastric lavage has a significant effect on patients with organophosphorus pesticide poisoning. It can effectively improve the success rate of rescue and the satisfaction of patients' nursing, and strive for rescue time to the greatest extent, which is unanimously recognized by the families of the patients.展开更多
This paper proposes a laterally graded junctionless transistor taking peak doping concentration near the source and drain region, and a gradual decrease in doping concentration towards the center of the channel to imp...This paper proposes a laterally graded junctionless transistor taking peak doping concentration near the source and drain region, and a gradual decrease in doping concentration towards the center of the channel to improve the I OFF and I ON/I OFF ratio. The decrease of doping concentration in the lateral direction of the channel region depletes a greater number of charge carriers compared to the uniformly doped channel in the OFF-state,which in turn suppresses the OFF state current flowing through the device without greatly affecting the ON state current.展开更多
基金The National Science and Technology Major Project(No.2017ZX05009-003)the National Key Research and Development Program of China(No.2017YFC0307604)the Talent Foundation of China University of Petroleum(No.Y1215042)。
文摘A size-dependent continuum-based model is developed for the functionally graded(FG)Timoshenko micro-beams with viscoelastic properties,in which material parameters vary according to the power law along its axial direction.The size effect is incorporated by employing the modified couple stress theory and Kelvin-Voigt viscoelastic model,so that viscous components are included in the stress and the deviatoric segments of the symmetric couple stress tensors.The components of strain,curvature,stress and couple stress are formulated by combining them with the Timoshenko beam theory.Based on the Hamilton principle,the governing differential equations and boundary conditions for the micro-beam are expressed with arbitrary beam section shape and arbitrary type of loads.The size effect,FG effect,Poisson effect,and the influence of the beam section shape on the mechanical behaviors of viscoelastic FG micro-beams are investigated by taking the simply supported micro-beam subjected to point load as an example.Results show that the size effect on deflection,normal stress and couple stress are obvious when the size of the micro-beam is small enough,and the FG effects are obvious when the size of the micro-beam is large enough.Moreover,the Poisson ratio influences the size effect significantly and the beam section shape is also an important factor influencing the mechanical behavior of the micro-beam.
基金supported in part by the National Natural Science Foundation of China(51807136 and 52377153).
文摘Insulation failures of epoxy spacers applied in gas insulated transmission line/switchgear(GIL/GIS)often occur,primarily due to electric field distortion.In this paper,a field graded coating CaCu_(3)Ti_(4)O_(12)(CCTO)is presented to enhance the flashover performance of a GIL/GIS spacer.First,CCTO layers of different thicknesses are deposited on the spacer surface using magnetron sputtering technology.Then,insulating properties of these sputtered spacers under alternating current,direct current,and polarity reversal(PR)voltages and with the existence of metal particles are researched by experimental and simulation methods.Results show the short-term(30 and 60 min)sputtering treatments have no obvious effect on improving insulating properties.
基金The authors of this paper acknowledge the supports from the National Key Research and Development Program of China(Grant No.2017YFC0307604)the Talent Foundation of China University of Petroleum(Grant No.Y1215042).
文摘This work focus on the mechanical behaviors,which are related to the size effect,functionally graded(FG)effect and Poisson effect,of an axially functionally graded(AFG)micro-beam whose elastic modulus varies according to sinusoidal law along its axial direction.The displacement field of the AFG micro-beam is set according to the Bernoulli-Euler beam theory.Employing the modified couple stress theory(MCST),the components of strain,curvature,stress and couple stress are expressed by the second derivative of the deflection of the AFG micro-beam.A size-dependent model related to FG effect and Poisson effect,which includes the formulations of bending stiffness,deflection,normal stress and couple stress,is developed to predict the mechanical behaviors of the AFG microbeam by employing the principle of minimum potential energy.The mechanical behaviors of a simply supported AFG micro-beam are numerically investigated using the developed model for demonstrating the size effects,FG effects and Poisson effects of the AFG micro-beam.Results show that the mechanical behaviors of AFG micro-beams are distinctly size-dependent only when the ratio of micro-beam height to material length-scale parameter is small enough.The FG parameter is an important factor that determines and regulates the size-dependent behaviors of AFG micro-beams.The influences of Poisson’s ratio on the mechanical behaviors of AFG micro-beams are not negligible,and should be also considered in the design and analysis of an AFG micro-beam.This work supplies a theoretical basis and a technical reference for the design and analysis of AFG micro-beams in the related regions.
文摘Objective: to explore the role and effect of rescue nursing intervention in emergency patients with organophosphorus pesticide poisoning. Methods: according to the random drawing method, 80 patients with organophosphorus and organophosphorus pesticide poisoning admitted to our hospital from May 2020 to April 2021 were selected and divided into analysis group and control group, which received interventional treatment and rescue treatment respectively. The intervention was carried out by conventional nursing methods in this group, and the nursing satisfaction rate of patients was compared with the rescue nursing effect of the control group and the analysis group. Results: the nursing satisfaction rate of patients in the analysis group who received rescue related treatment was significantly higher than that in the control group who received routine nursing measures, while the rescue treatment score of patients in the control group was significantly lower than the effectiveness score. There was clinical correlation between the two groups (P < 0.05). The incidence of adverse reactions in the analysis group was better than that in the control group, and the difference between the two groups was clinically comparable (P < 0.05). Conclusion: gastric lavage has a significant effect on patients with organophosphorus pesticide poisoning. It can effectively improve the success rate of rescue and the satisfaction of patients' nursing, and strive for rescue time to the greatest extent, which is unanimously recognized by the families of the patients.
文摘This paper proposes a laterally graded junctionless transistor taking peak doping concentration near the source and drain region, and a gradual decrease in doping concentration towards the center of the channel to improve the I OFF and I ON/I OFF ratio. The decrease of doping concentration in the lateral direction of the channel region depletes a greater number of charge carriers compared to the uniformly doped channel in the OFF-state,which in turn suppresses the OFF state current flowing through the device without greatly affecting the ON state current.
