It is critical for the material to be of active supporting capacity before initial collapse ot mare root wltn supermgn water material backfill mining, and the maximum bending moment should be first calculated in order...It is critical for the material to be of active supporting capacity before initial collapse ot mare root wltn supermgn water material backfill mining, and the maximum bending moment should be first calculated in order to determine the initial collapse span. In the light of principal of virtual work, the simple expression of deflection, bending moment of elastic clamped plate were deduced under the condition of vertical uniform distributed load, horizontal pressure and supporting by elastic foundation, and then, the maximal bending moment expression was derived too. At the same time, the influence degree on square clamped plate by adding horizontal pressure and elastic foundation were analyzed. The results show that the effect of horizontal pressure on maximal bending moment can be ignored when the value of horizontal pressure is two orders of magni- tude less than that of coeificient of elastic stiffness existing elastic foundation.展开更多
With the terms of the exact series solution taken as trial functions, the method of point collocation was used to calculate the large deflection of a circular plate. The axisymmetrical bending formulae were developed ...With the terms of the exact series solution taken as trial functions, the method of point collocation was used to calculate the large deflection of a circular plate. The axisymmetrical bending formulae were developed for the calculation of a circular plate subjected to polynomial distributed loads, a concentrated load at the center, uniform radial forces and moments along the edge or their combinations. The support may be elastic. The buckling load was calculated. Under action of uniformly distributed load, central load or their compound load, solutions were compared with those obtained by other methods. Buckling beyond critical thrust was compared with that calculated by the power series method. The method presented in this paper has advantages of wide convergent range, high precision and short computing time. Moreover, the computing time is nearly independent of the complexity of the loads.展开更多
This research is showing the effect of increasing an Fe extracting from the compression strength, tension and bending moment. The variations in this experiment are the increasing of Fe extracting 0.5%, 1% and 1.5% of ...This research is showing the effect of increasing an Fe extracting from the compression strength, tension and bending moment. The variations in this experiment are the increasing of Fe extracting 0.5%, 1% and 1.5% of concrete volume. Water Cement Ratio （WCR） variation of 0.48, 0.56 and 0.60. The result of increasing 1.5% Fe extracting causes the increasing of tension strength 44.028 kN/cm2, the increasing of slit tension strength 2.226 kN/cm2, the increasing of bending moment 14.81 kN/cm2 from normal concrete. 0.48 WCR produces tension strength, slit tension strength and bending moment more than 0.56 and 0.60 WCR. The increasing of Fe extracting with the distribution variation area and the spread concrete in the tension concrete area produce 3.705 kN/cm2 bending moment higher than the spread fiber in all of concrete area. The 4 cm fiber length produces the higher bending moment than the 2 cm fiber length. The difference is equally 5.185 kN/cm2. The combination result of the examined acting varieties by continuation statistic test gives the result to get the maximum tension and split tensile. It is a concrete combination of increasing 1.5% fiber percentage, 0.48 WCR, full spreading area and the 4 cm fiber length. The maximum bending moment is the increasing of 0.5% fiber percentage, 0.48 WCR, full spreading area and the 4 cm fiber length.展开更多
This paper reports the problems that elderly people have when they stand up from a chair, and proposes an adequate standing-up procedure that solves these problems. The important points for an adequate standing-up pro...This paper reports the problems that elderly people have when they stand up from a chair, and proposes an adequate standing-up procedure that solves these problems. The important points for an adequate standing-up procedure are ＂leaning the upper body forward＂ and ＂pulling the legs to the side＂. Furthermore, this paper proposes a standing-up support tool. The characteristics of the support tool are a cushion-type shape with an adjustable flange and an air-pressure-driven mechanism. When the proposed standing-up procedure and support tool are applied to elderly people, the measured values related to standing-up, such as maximum acceleration, arm force, standing-up time, heel position and forward-bending angle, are improved. Furthermore, elderly people felt that it made the standing-up action easy. We could confirm the effectiveness of the proposed standing-up procedure and support tool.展开更多
Experimental study was carried out on the in-plane bending behavior of glass plates without lateral supports, and the effects of the factors, such as height-to-span ratio, on the stability of glass panels were studied...Experimental study was carried out on the in-plane bending behavior of glass plates without lateral supports, and the effects of the factors, such as height-to-span ratio, on the stability of glass panels were studied. Results show that the in-plane bending glass plates with both ends simply supported and their upper edge free lose overall stability under loads, which belongs to the limit-point type of instability. It is found that the buckling load increases linearly with the increase of height-to-span ratio of the glass plates. The lateral stress of in-plane bending glass plates without lateral supports increases linearly under loads; while the large-area stress increases nonlinearly and the lateral stress is not the controlling factor of instability. In finite element analysis, the first buckling mode is regarded as the initial imperfection and imposed on the model as 1/1000 of the span of the components. The numerical buckling load according to the theory of large deflection is less than the experiment result, which is more conservative and can provide some reference for design. For the design method, when the in-plane load is imposed on the glass plate, its lateral strength and the deflection should be verified. Considering the stability of the in-plane bending glass plate without reliable lateral support, buckling is another possible failure mode and calls for verification.展开更多
A design procedure for improving the efficiency of a transonic compressor blading was proposed based on a rapid generation method for three-dimensional blade configuration and computational meshes, a three-dimensional...A design procedure for improving the efficiency of a transonic compressor blading was proposed based on a rapid generation method for three-dimensional blade configuration and computational meshes, a three-dimensional Navier-Stokes solver and an optimization approach. The objective of the present paper is to design a transonic compressor blading optimized only by selection of the locations of maximum camber and maximum thickness for the airfoils at different span heights and to study how do these two design parameters affect the blade performance. The blading configuration and the computational meshes can be obtained very rapidly for any given combination of maximum camber and maximum thickness. The computational grid system generated is used for the Navier-Stokes solution to predict adiabatic efficiency, total pressure ratio and flow rate. As a main result of the optimization, adiabatic efficiency was successfully improved.展开更多
A sixth-order accurate wavelet integral collocation method is proposed for solving high-order nonlinear boundary value problems in three dimensions.In order to realize the establishment of this method,an approximate e...A sixth-order accurate wavelet integral collocation method is proposed for solving high-order nonlinear boundary value problems in three dimensions.In order to realize the establishment of this method,an approximate expression of multiple integrals of a continuous function defined in a three-dimensional bounded domain is proposed by combining wavelet expansion and Lagrange boundary extension.Through applying such an integral technique,during the solution of nonlinear partial differential equations,the unknown function and its lower-order partial derivatives can be approximately expressed by its highest-order partial derivative values at nodes.A set of nonlinear algebraic equations with respect to these nodal values of the highest-order partial derivative is obtained using a collocation method.The validation and convergence of the proposed method are examined through several benchmark problems,including the eighth-order two-dimensional and fourth-order three-dimensional boundary value problems and the large deflection bending of von Karman plates.Results demonstrate that the present method has higher accuracy and convergence rate than most existing numerical methods.Most importantly,the convergence rate of the proposed method seems to be independent of the order of the differential equations,because it is always sixth order for second-,fourth-,sixth-,and even eighth-order problems.展开更多
A conventional Fowler flap is designed to improve the take-off and landing performances of an aircraft. Because the flight states of general aviation aircraft vary significantly. A Fowler flap with a double-sliding tr...A conventional Fowler flap is designed to improve the take-off and landing performances of an aircraft. Because the flight states of general aviation aircraft vary significantly. A Fowler flap with a double-sliding track has been designed, which is ca- pable of changing airfoil camber while cruising and climbing as well as meeting low-speed performance requirements. The aerodynamic characteristics of the variable camber Fowler flap were studied by computational simulation, and cambering was found to be beneficial for improving the lift-to-drag ratio when the lift coefficient was larger than the critical value, below which decambering was more effective; this critical value differed somewhat under different conditions. Taking the mecha- nism into account, the take-off and landing configurations were optimized on the basis of the GA （W）-1 airfoil with a 30% chord Fowler flap. Compared with reference configuration, the maximum lift coefficient of optimized take-off configuration was increased by 6.6% as well as the stalling angle and the lift-to-drag ratio were increased by 1.3° and 7.58%, respectively. Moreover, the maximum lift coefficient of the optimized landing configuration was increased by 6.3%, and the stalling angle was increased by 1.1°; however, the nose-down pitching moment of both configurations increased. Similar results were at- rained on a general aviation aircraft wing/body combination nism was established in a computer-aided design system, achieved by the double-sliding track. A 3D model of the variable-camber Fowler flap driving mecha- and the results showed that all design configurations could be展开更多
基金Supported by the National Natural Science Foundation of China （41071273） the Special Research Fund for the Doctoral Program of Higher Education of China （200090095110002）
文摘It is critical for the material to be of active supporting capacity before initial collapse ot mare root wltn supermgn water material backfill mining, and the maximum bending moment should be first calculated in order to determine the initial collapse span. In the light of principal of virtual work, the simple expression of deflection, bending moment of elastic clamped plate were deduced under the condition of vertical uniform distributed load, horizontal pressure and supporting by elastic foundation, and then, the maximal bending moment expression was derived too. At the same time, the influence degree on square clamped plate by adding horizontal pressure and elastic foundation were analyzed. The results show that the effect of horizontal pressure on maximal bending moment can be ignored when the value of horizontal pressure is two orders of magni- tude less than that of coeificient of elastic stiffness existing elastic foundation.
文摘With the terms of the exact series solution taken as trial functions, the method of point collocation was used to calculate the large deflection of a circular plate. The axisymmetrical bending formulae were developed for the calculation of a circular plate subjected to polynomial distributed loads, a concentrated load at the center, uniform radial forces and moments along the edge or their combinations. The support may be elastic. The buckling load was calculated. Under action of uniformly distributed load, central load or their compound load, solutions were compared with those obtained by other methods. Buckling beyond critical thrust was compared with that calculated by the power series method. The method presented in this paper has advantages of wide convergent range, high precision and short computing time. Moreover, the computing time is nearly independent of the complexity of the loads.
文摘This research is showing the effect of increasing an Fe extracting from the compression strength, tension and bending moment. The variations in this experiment are the increasing of Fe extracting 0.5%, 1% and 1.5% of concrete volume. Water Cement Ratio （WCR） variation of 0.48, 0.56 and 0.60. The result of increasing 1.5% Fe extracting causes the increasing of tension strength 44.028 kN/cm2, the increasing of slit tension strength 2.226 kN/cm2, the increasing of bending moment 14.81 kN/cm2 from normal concrete. 0.48 WCR produces tension strength, slit tension strength and bending moment more than 0.56 and 0.60 WCR. The increasing of Fe extracting with the distribution variation area and the spread concrete in the tension concrete area produce 3.705 kN/cm2 bending moment higher than the spread fiber in all of concrete area. The 4 cm fiber length produces the higher bending moment than the 2 cm fiber length. The difference is equally 5.185 kN/cm2. The combination result of the examined acting varieties by continuation statistic test gives the result to get the maximum tension and split tensile. It is a concrete combination of increasing 1.5% fiber percentage, 0.48 WCR, full spreading area and the 4 cm fiber length. The maximum bending moment is the increasing of 0.5% fiber percentage, 0.48 WCR, full spreading area and the 4 cm fiber length.
文摘This paper reports the problems that elderly people have when they stand up from a chair, and proposes an adequate standing-up procedure that solves these problems. The important points for an adequate standing-up procedure are ＂leaning the upper body forward＂ and ＂pulling the legs to the side＂. Furthermore, this paper proposes a standing-up support tool. The characteristics of the support tool are a cushion-type shape with an adjustable flange and an air-pressure-driven mechanism. When the proposed standing-up procedure and support tool are applied to elderly people, the measured values related to standing-up, such as maximum acceleration, arm force, standing-up time, heel position and forward-bending angle, are improved. Furthermore, elderly people felt that it made the standing-up action easy. We could confirm the effectiveness of the proposed standing-up procedure and support tool.
文摘Experimental study was carried out on the in-plane bending behavior of glass plates without lateral supports, and the effects of the factors, such as height-to-span ratio, on the stability of glass panels were studied. Results show that the in-plane bending glass plates with both ends simply supported and their upper edge free lose overall stability under loads, which belongs to the limit-point type of instability. It is found that the buckling load increases linearly with the increase of height-to-span ratio of the glass plates. The lateral stress of in-plane bending glass plates without lateral supports increases linearly under loads; while the large-area stress increases nonlinearly and the lateral stress is not the controlling factor of instability. In finite element analysis, the first buckling mode is regarded as the initial imperfection and imposed on the model as 1/1000 of the span of the components. The numerical buckling load according to the theory of large deflection is less than the experiment result, which is more conservative and can provide some reference for design. For the design method, when the in-plane load is imposed on the glass plate, its lateral strength and the deflection should be verified. Considering the stability of the in-plane bending glass plate without reliable lateral support, buckling is another possible failure mode and calls for verification.
文摘A design procedure for improving the efficiency of a transonic compressor blading was proposed based on a rapid generation method for three-dimensional blade configuration and computational meshes, a three-dimensional Navier-Stokes solver and an optimization approach. The objective of the present paper is to design a transonic compressor blading optimized only by selection of the locations of maximum camber and maximum thickness for the airfoils at different span heights and to study how do these two design parameters affect the blade performance. The blading configuration and the computational meshes can be obtained very rapidly for any given combination of maximum camber and maximum thickness. The computational grid system generated is used for the Navier-Stokes solution to predict adiabatic efficiency, total pressure ratio and flow rate. As a main result of the optimization, adiabatic efficiency was successfully improved.
基金supported by the National Natural Science Foundation of China(Grant Nos.11925204 and 12172154)the 111 Project(Grant No.B14044)the National Key Project of China(Grant No.GJXM92579).
文摘A sixth-order accurate wavelet integral collocation method is proposed for solving high-order nonlinear boundary value problems in three dimensions.In order to realize the establishment of this method,an approximate expression of multiple integrals of a continuous function defined in a three-dimensional bounded domain is proposed by combining wavelet expansion and Lagrange boundary extension.Through applying such an integral technique,during the solution of nonlinear partial differential equations,the unknown function and its lower-order partial derivatives can be approximately expressed by its highest-order partial derivative values at nodes.A set of nonlinear algebraic equations with respect to these nodal values of the highest-order partial derivative is obtained using a collocation method.The validation and convergence of the proposed method are examined through several benchmark problems,including the eighth-order two-dimensional and fourth-order three-dimensional boundary value problems and the large deflection bending of von Karman plates.Results demonstrate that the present method has higher accuracy and convergence rate than most existing numerical methods.Most importantly,the convergence rate of the proposed method seems to be independent of the order of the differential equations,because it is always sixth order for second-,fourth-,sixth-,and even eighth-order problems.
文摘A conventional Fowler flap is designed to improve the take-off and landing performances of an aircraft. Because the flight states of general aviation aircraft vary significantly. A Fowler flap with a double-sliding track has been designed, which is ca- pable of changing airfoil camber while cruising and climbing as well as meeting low-speed performance requirements. The aerodynamic characteristics of the variable camber Fowler flap were studied by computational simulation, and cambering was found to be beneficial for improving the lift-to-drag ratio when the lift coefficient was larger than the critical value, below which decambering was more effective; this critical value differed somewhat under different conditions. Taking the mecha- nism into account, the take-off and landing configurations were optimized on the basis of the GA （W）-1 airfoil with a 30% chord Fowler flap. Compared with reference configuration, the maximum lift coefficient of optimized take-off configuration was increased by 6.6% as well as the stalling angle and the lift-to-drag ratio were increased by 1.3° and 7.58%, respectively. Moreover, the maximum lift coefficient of the optimized landing configuration was increased by 6.3%, and the stalling angle was increased by 1.1°; however, the nose-down pitching moment of both configurations increased. Similar results were at- rained on a general aviation aircraft wing/body combination nism was established in a computer-aided design system, achieved by the double-sliding track. A 3D model of the variable-camber Fowler flap driving mecha- and the results showed that all design configurations could be
