Dynamic disasters,such as rock burst due to the breaking of large area stiff roof strata,are known to occur in the hard rock strata of coal mines.In this paper,mechanical models of the fracturing processes of thick ha...Dynamic disasters,such as rock burst due to the breaking of large area stiff roof strata,are known to occur in the hard rock strata of coal mines.In this paper,mechanical models of the fracturing processes of thick hard rock strata were established based on the thick plate theory and numerical simulations.The results demonstrated that,based on the fracture characteristics of the thick hard rock strata,four fracture models could be analyzed in detail,and the corresponding theoretical failure criteria were determined in detail.In addition,the influence of weak interlayer position on the fracture models and ground pressure of rock strata is deeply analyzed,and six numerical simulation schemes have been implemented.The results showed that the working face pressure caused by the independent movement of the lower layer is relatively low.The different fracture type of the thick hard rock strata had different demands on the working resistance of the hydraulic powered supports.The working resistance of the hydraulic powered supports required by the stratified movements was lower than that of the non-stratified movements.展开更多
Aiming at the fatigue and comfort issues of human-machine contact interface in automobile driving and based on physiological and anatomical principle, the physiological and biochemical process of muscles and nerves in...Aiming at the fatigue and comfort issues of human-machine contact interface in automobile driving and based on physiological and anatomical principle, the physiological and biochemical process of muscles and nerves in the formation and development of fatigue is analyzed systematically. The fatigue-causing physiological characteristic indexes are mapped to biomechanical indexes like muscle stress-strain, the compression deformation of blood vessels and nerves etc. from the perspective of formation mechanism. The geometrical model of skeleton and parenchyma is established by applying CT-scanned body data and MRI images. The general rule of comfort body pressure distribution is acquired through the analysis of anatomical structure of buttocks and femoral region. The comprehensive test platform for sitting comfort of 3D adjustable contact interface is constructed. The test of body pressure distribution of human-machine contact interface and its comparison with subjective evaluation indicates that the biomechanical indexes of automobile driving human-machine contact interface and body pressure distribution rule studied can effectively evaluate the fatigue and comfort issues of human-machine contact interface and provide theoretical basis for the optimal design of human-machine contact interface.展开更多
In this paper, the mechanism of the interaction between the breast wall of mound breakwater and waves is expounded, then some new views and the law of variation of horizontal and vertical wave pressure over the breast...In this paper, the mechanism of the interaction between the breast wall of mound breakwater and waves is expounded, then some new views and the law of variation of horizontal and vertical wave pressure over the breast wall are put forward. The results of this study have been adopted in the Specifications of Fishery Harbour Breakwater by the Ministry of Agricultures.展开更多
In this paper, the calculating charts and formulae about wave pressure on the breast wall are derived with seven parameters on the basis of physical model study. The verification shows that the charts agree with the e...In this paper, the calculating charts and formulae about wave pressure on the breast wall are derived with seven parameters on the basis of physical model study. The verification shows that the charts agree with the example, and are adopted in the Specifications of Fishery Harbours Breakwater by the Ministry of Agricultures.展开更多
In order to improve lubricating characteristics of slippers in an axial piston pump, the combining center cavity slipper approach was proposed based on slipper shape and moving characteristic. The cylindrical coordina...In order to improve lubricating characteristics of slippers in an axial piston pump, the combining center cavity slipper approach was proposed based on slipper shape and moving characteristic. The cylindrical coordinate was used in the lubricant area and mesh was made. The blockweight approach was implemented to deal with non-coincidence of mesh and shallow recess border in numerical method. The finite control volume method was applied in calculating pressure distribution. The flow conservation equation and film thickness model were resolved through Gauss-Siedel relaxation iteration. The calculation and analysis results indicate that compared to the slipper (1) slip- per pressure distribution is improved; (2) hydrodynamic pressure of the combining slipper is greatly increased; (3) inclining degree is greatly reduced; (4) negative pressure in lubricant film disappear. So the combining center cavity slipper is lubricated better.展开更多
Laboratory experiments have been carried out to study the fluid flow in the wellbore of a horizontal gas well during the production process.The related pressure distribution has been determined considering different c...Laboratory experiments have been carried out to study the fluid flow in the wellbore of a horizontal gas well during the production process.The related pressure distribution has been determined considering different cases(different inflow media,different perforation opening methods and different liquid holdup).It has been found that the larger the fluid flow rate,the greater the pressure changes in the wellbore under the same hole opening mode.The uniformity of the perforation opening method was also an important factor affecting the magnitude of the wellbore pressure change.The liquid holdup also affected the pressure distribution,especially when the gas volumetric flow rate exceeded 200 m3/h.Comparison of the outcomes of the present experimental study with the predictions of a theoretical model available in the literature has provided a relative error smaller than 20%.展开更多
Flexible pressure monitoring device can help correct the sitting posture and prevent health problems(e.g.,deformity of spinal column and musculoskeletal disease).Currently,most measurement systems hinder their wide ap...Flexible pressure monitoring device can help correct the sitting posture and prevent health problems(e.g.,deformity of spinal column and musculoskeletal disease).Currently,most measurement systems hinder their wide applications owing to the high cost or low accuracy.In this study,a flexible sitting pressure measurement system was proposed based on a textile-based capacitive pressure sensor array in order to measure sitting pressure distribution simply and conveniently.The capacitive pressure sensor array is sandwich structure composed of a high-density sponge layer and two electrode array fabrics,which possesses high resolution(2.26 sensors/cm2),high sensitivity(0.701 kPa-1)and fast response(≤35 ms).It is worth noting that the raw materials of the sensing fabric include commercialized copper sheets and polyester yarns.The as-prepared pressure measurement system can accurately measure the pressure distribution nephogram for sitting posture analysis.The sitting pressure of 10 volunteers was measured and six types of posture were distinguished clearly.展开更多
The expressions of the radius and the surface tension of surface of tension Rs and γs in terms of the pressure distribution for nanoscale liquid threads are of great importance for molecular dynamics (MD) simulatio...The expressions of the radius and the surface tension of surface of tension Rs and γs in terms of the pressure distribution for nanoscale liquid threads are of great importance for molecular dynamics (MD) simulations of the interfacial phenomena of nanoscale fluids; these two basic expressions are derived in this paper. Although these expressions were derived first in the literature[Kim B G, Lee J S, Han M H, and Park S, 2006 Nanoscale and Microscale Thermophysical Engineering, 10, 283] and used widely thereafter, the derivation is wrong both in logical structure and physical thought. In view of the importance of these basic expressions, the logic and physical mistakes appearing in that derivation are pointed out.展开更多
Based on incompressible viscous fluid Navier-stokes equation and k-ε 2-equations turbulent model, an investigation on 3D turbulent flow field around four kinds of train models has been made by finite element method. ...Based on incompressible viscous fluid Navier-stokes equation and k-ε 2-equations turbulent model, an investigation on 3D turbulent flow field around four kinds of train models has been made by finite element method. From the calculation, the pressure distribution characters of now field around high-speed trains have been obtained. It is significant for strength design of the high-speed train body, for resisting wind design of the facilities beside the high-speed railways and for determining the aerodynamic force of induced air to the human body near the railways.展开更多
In this article, the governing equations for the unsteady flow of viscoelastic fluid in the eccentric annulus with the inner cylinder reciprocating axially and the expression of the pressure distribution on the wall o...In this article, the governing equations for the unsteady flow of viscoelastic fluid in the eccentric annulus with the inner cylinder reciprocating axially and the expression of the pressure distribution on the wall of the inner cylinder of the annulus are established and derived, respectively, under the bipolar coordinate system. The equations and the expression are solved and calculated numerically using the finite difference method, respectively. The curves of the pressure distribution on the wall of the inner cylinder of the aqueous solution of Hydrolyzed Polyacrylamide (HPAM) are plotted and the influences of annular eccentricity, stroke, and stroke frequency on the pressure distribution are analyzed.展开更多
Pressure distribution is important information for engineers during an aerodynamic design process. Pressure Distribution Oriented(PDO) optimization design has been proposed to introduce pressure distribution manipulat...Pressure distribution is important information for engineers during an aerodynamic design process. Pressure Distribution Oriented(PDO) optimization design has been proposed to introduce pressure distribution manipulation into traditional performance dominated optimization.In previous PDO approaches, constraints or manual manipulation have been used to obtain a desirable pressure distribution. In the present paper, a new Pressure Distribution Guided(PDG) method is developed to enable better pressure distribution manipulation while maintaining optimization efficiency. Based on the RBF-Assisted Differential Evolution(RADE) algorithm, a surrogate model is built for target pressure distribution features. By introducing individuals suggested by suboptimization on the surrogate model into the population, the direction of optimal searching can be guided. Pressure distribution expectation and aerodynamic performance improvement can be achieved at the same time. The improvements of the PDG method are illustrated by comparing its design results and efficiency on airfoil optimization test cases with those obtained using other methods. Then the PDG method is applied on a dual-aisle airplane’s inner-board wing design. A total drag reduction of 8 drag counts is achieved.展开更多
For controlling dexterous prosthetic hand with a high number of active Degrees of Freedom (DOF), it is necessary to reliably extract control volitions of finger motions from the human body. In this study, a large va...For controlling dexterous prosthetic hand with a high number of active Degrees of Freedom (DOF), it is necessary to reliably extract control volitions of finger motions from the human body. In this study, a large variety of finger motions are discriminated based on the diversities of the pressure distribution produced by the mechanical actions of muscles on the forearm. The pressure distribution patterns corresponding to the motions were measured by sensor array which is composed of 32 Force Sensitive Resistor (FSR) sensors. In order to map the pressure patterns with different finger motions, a multiclass classifier was designed based on the Support Vector Machine (SVM) algorithm. The multi-subject experiments show that it is possible to identify as many as seventeen different finger motions, including individual finger motions and multi-finger grasping motions, with the accuracy above 99% in the in-session validation. Further, the cross-session validation demonstrates that the performance of the proposed method is robust for use if the FSR array is not reset. The results suggest that the proposed method has great application prospects for the control of multi-DOF dexterous hand prosthesis.展开更多
In the field of supercritical wing design, various principles and rules have been summarized through theoretical and experimental analyses. Compared with black-box relationships between geometry parameters and perform...In the field of supercritical wing design, various principles and rules have been summarized through theoretical and experimental analyses. Compared with black-box relationships between geometry parameters and performances, quantitative physical laws about pressure distributions and performances are clearer and more beneficial to designers. With the advancement of computational fluid dynamics and computational intelligence, discovering new rules through statistical analysis on computers has become increasingly attractive and affordable. This paper proposes a novel sampling method for the statistical study on pressure distribution features and performances, so that new physical laws can be revealed. It utilizes an adaptive sampling algorithm, of which the criteria are developed based on Kullback–Leibler divergence and Euclidean distance.In this paper, the proposed method is employed to generate airfoil samples to study the relationships between the supercritical pressure distribution features and the drag divergence Mach number as well as the drag creep characteristic. Compared with conventional sampling methods, the proposed method can efficiently distribute samples in the pressure distribution feature space rather than directly sampling airfoil geometry parameters. The corresponding geometry parameters are searched and found under constraints, so that supercritical airfoil samples that are well distributed in the pressure distribution space are obtained. These samples allow statistical studies to obtain more reliable and universal aerodynamic rules that can be applied to supercritical airfoil designs.展开更多
This paper provides a novel three-dimensional meshless Galerkin for horizontal well reservoir simulation.The pressure function is approached by moving least-square method which consists of weight function,basic functi...This paper provides a novel three-dimensional meshless Galerkin for horizontal well reservoir simulation.The pressure function is approached by moving least-square method which consists of weight function,basic function and coefficient.Based on Galerkin principle and use penalty function method,the paper deduces the meshless Galerkin numerical linear equations.Cut off the pressure distribution of the horizontal section from the simulation database of horizontal well reservoir.It demonstrates that meshless Galerkin is a feasible numerical method for the horizontal well reservoir simulation.It is useful to research complex reservoir.展开更多
A series of wind tunnel tests was conducted to examine how an end plate affects the pressure distributions of two wings with leading edge(LE) sweep angles of 23° and 40°. All the experiments were carried o...A series of wind tunnel tests was conducted to examine how an end plate affects the pressure distributions of two wings with leading edge(LE) sweep angles of 23° and 40°. All the experiments were carried out at a midchord Reynolds number of 8×10~5, covering an angle of attack(AOA) range from -2° to 14°. Static pressure distribution measurements were acquired over the upper surfaces of the wings along three chordwise rows and one spanwise direction at the wing quarter-chord line. The results of the tests confirm that at a particular AOA, increasing the sweep angle causes a noticeable decrease in the upper-surface suction pressure. Furthermore, as the sweep angle increases, the development of a laminar separation bubble near the LEs of the wings takes place at higher AOAs. On the other hand, spanwise pressure measurements show that increasing the wing sweep angle results in forming a stronger vortex on the quarter-chord line which has lower sensitivity to AOA variation and remains substantially attached to the wing surface for higher AOAs than that can be achieved in the case of a lower sweep angle. In addition, data obtained indicate that installing an end plate further reinforces the spanwise flow over the wing surface, thus affecting the pressure distribution.展开更多
The current paper presents the result of a study on determining the pressure distribution along the surface of a foil section by using measured velocity field data and the Reynolds Averaged Navier-Stokes equations. Th...The current paper presents the result of a study on determining the pressure distribution along the surface of a foil section by using measured velocity field data and the Reynolds Averaged Navier-Stokes equations. The results are compared with the measured pressure data and show its satisfaction. It is a try to find a new way to determine pressure by combining the experimental data and CFD method.展开更多
In this paper the pressure distribution of the gaseous flow in a microchannel is studied via a lattice Boltzmann equation(LBE)method.With effective relaxation times and a generalized second order slip boundary conditi...In this paper the pressure distribution of the gaseous flow in a microchannel is studied via a lattice Boltzmann equation(LBE)method.With effective relaxation times and a generalized second order slip boundary condition,the LBE can be used to simulate rarefied gas flows from slip to transition regimes.The Knudsen minimum phenomena of mass flow rate in the pressure driven flow is also investigated.The effects of Knudsen number(rarefaction effect),pressure ratio and aspect ratio(compression effect)on the pressure distribution are analyzed.It is found the rarefaction effect tends to the curvature of the nonlinear pressure distribution,while the compression effect tends to enhance its nonlinearity.The combined effects lead to a local minimum of the pressure deviation.Furthermore,it is also found that the relationship between the pressure deviation and the aspect ratio follows a pow-law.展开更多
In the present paper,two-and three-dimensional velocity potentials generated by pulsating pressure distributions of infinite extent on the free surface of infinite-depth waters are strictly derived based on special ca...In the present paper,two-and three-dimensional velocity potentials generated by pulsating pressure distributions of infinite extent on the free surface of infinite-depth waters are strictly derived based on special cases of concentrated pulsating pressure.The far-field asymptotic behaviour of the potentials and the radiation conditions to be satisfied by them are discussed. It is proved in a general sense that the potentials should be composed of a forced wave component,a free wave component and a local disturbance component.The radiation condition of the forced wave component should correspond to the far-field asymptotic behaviour of the pressure distribution,Hence,the formulation of radiation conditions for the second-order diffraction potentials has theoretically become clear,The radiation conditions for two-and three-dimensional problems are explicitly given in the paper.展开更多
By analyzing the differences between binaural recording and real listening, it was deduced that there were some unrevealed auditory localization clues, and the sound pressure distribution pattern at the entrance of ea...By analyzing the differences between binaural recording and real listening, it was deduced that there were some unrevealed auditory localization clues, and the sound pressure distribution pattern at the entrance of ear canal was probably a clue. It was proved through the listening test that the unrevealed auditory localization clues really exist with the reduction to absurdity. And the effective frequency bands of the unrevealed localization clues were in- duced and summed. The result of finite element based simulations showed that the pressure distribution at the entrance of ear canal was non-uniform, and the pattern was related to the direction of sound source. And it was proved that the sound pressure distribution pattern at the entrance of the ear canal carried the sound source direction information and could be used as an unrevealed localization clue. The frequency bands in which the sound pressure distribution patterns had significant differences between front and back sound source directions were roughly matched with the effective frequency bands of unrevealed localization clues obtained from the listening tests. To some extent, it supports the pattern could be a kind of unrevealed auditory hypothesis that the sound pressure distribution localization clues.展开更多
A wind tunnel tests with different configurations,pitch and yaw angles were performed to study the wind load characteristics of the rigid model of the airship Zhiyuan-1. The rigid model was aimed to simulate a technic...A wind tunnel tests with different configurations,pitch and yaw angles were performed to study the wind load characteristics of the rigid model of the airship Zhiyuan-1. The rigid model was aimed to simulate a technical demonstrating stratospheric airship named Zhiyuan-1 according to the similarity principle of geometric and Reynolds number. Based on the results of wind tunnel test,the features of pressure coefficient distributions on the surface of the airship were described. It was indicated that the fins and the gondola of airship hardly have the effect on the pressure distribution on the surface of airship,but have obviously effect on the local areas near the fins and the gondola.展开更多
基金the Beijing Outstanding Young Scientist Program of China(No.BJJWZYJH01201911413037)projects(Nos.41877257 and 51622404)supported by National Natural Science Foundation of China+1 种基金Shaanxi Coal Group Key Project of China(No.2018SMHKJ-A-J-03)the Fundamental Research Funds for the Central Universities of China(No.2021YJSLJ23)。
文摘Dynamic disasters,such as rock burst due to the breaking of large area stiff roof strata,are known to occur in the hard rock strata of coal mines.In this paper,mechanical models of the fracturing processes of thick hard rock strata were established based on the thick plate theory and numerical simulations.The results demonstrated that,based on the fracture characteristics of the thick hard rock strata,four fracture models could be analyzed in detail,and the corresponding theoretical failure criteria were determined in detail.In addition,the influence of weak interlayer position on the fracture models and ground pressure of rock strata is deeply analyzed,and six numerical simulation schemes have been implemented.The results showed that the working face pressure caused by the independent movement of the lower layer is relatively low.The different fracture type of the thick hard rock strata had different demands on the working resistance of the hydraulic powered supports.The working resistance of the hydraulic powered supports required by the stratified movements was lower than that of the non-stratified movements.
基金Selected from Proceedings of the 7th International Conference on Frontiers of Design and Manufacturing(ICFDM'2006)This project is supported by National Natural Science Foundation of China(No.50475090) Program for New Century Excellent Talents in University,China(040927).
文摘Aiming at the fatigue and comfort issues of human-machine contact interface in automobile driving and based on physiological and anatomical principle, the physiological and biochemical process of muscles and nerves in the formation and development of fatigue is analyzed systematically. The fatigue-causing physiological characteristic indexes are mapped to biomechanical indexes like muscle stress-strain, the compression deformation of blood vessels and nerves etc. from the perspective of formation mechanism. The geometrical model of skeleton and parenchyma is established by applying CT-scanned body data and MRI images. The general rule of comfort body pressure distribution is acquired through the analysis of anatomical structure of buttocks and femoral region. The comprehensive test platform for sitting comfort of 3D adjustable contact interface is constructed. The test of body pressure distribution of human-machine contact interface and its comparison with subjective evaluation indicates that the biomechanical indexes of automobile driving human-machine contact interface and body pressure distribution rule studied can effectively evaluate the fatigue and comfort issues of human-machine contact interface and provide theoretical basis for the optimal design of human-machine contact interface.
文摘In this paper, the mechanism of the interaction between the breast wall of mound breakwater and waves is expounded, then some new views and the law of variation of horizontal and vertical wave pressure over the breast wall are put forward. The results of this study have been adopted in the Specifications of Fishery Harbour Breakwater by the Ministry of Agricultures.
文摘In this paper, the calculating charts and formulae about wave pressure on the breast wall are derived with seven parameters on the basis of physical model study. The verification shows that the charts agree with the example, and are adopted in the Specifications of Fishery Harbours Breakwater by the Ministry of Agricultures.
基金Supported by the National Key Laboratory Foundation Project(9140C3403010903)
文摘In order to improve lubricating characteristics of slippers in an axial piston pump, the combining center cavity slipper approach was proposed based on slipper shape and moving characteristic. The cylindrical coordinate was used in the lubricant area and mesh was made. The blockweight approach was implemented to deal with non-coincidence of mesh and shallow recess border in numerical method. The finite control volume method was applied in calculating pressure distribution. The flow conservation equation and film thickness model were resolved through Gauss-Siedel relaxation iteration. The calculation and analysis results indicate that compared to the slipper (1) slip- per pressure distribution is improved; (2) hydrodynamic pressure of the combining slipper is greatly increased; (3) inclining degree is greatly reduced; (4) negative pressure in lubricant film disappear. So the combining center cavity slipper is lubricated better.
基金supported by the National Major Scientific and Technological Special Project(2016ZX05056004-002)Foundation of the Educational Commission of Hubei Province of China(No.Q20191310)National Natural Science Foundation of China(Grant No.61572084).
文摘Laboratory experiments have been carried out to study the fluid flow in the wellbore of a horizontal gas well during the production process.The related pressure distribution has been determined considering different cases(different inflow media,different perforation opening methods and different liquid holdup).It has been found that the larger the fluid flow rate,the greater the pressure changes in the wellbore under the same hole opening mode.The uniformity of the perforation opening method was also an important factor affecting the magnitude of the wellbore pressure change.The liquid holdup also affected the pressure distribution,especially when the gas volumetric flow rate exceeded 200 m3/h.Comparison of the outcomes of the present experimental study with the predictions of a theoretical model available in the literature has provided a relative error smaller than 20%.
基金Fundamental Research Fund for the Central Universities,China(Nos.2232020G-01 and 19D110106)Young Elite Scientists Sponsorship Program by China Association for Science and Technology,China(No.2017QNRC001)Graduate Student Innovation Fund of Donghua University,China(No.20D310111)。
文摘Flexible pressure monitoring device can help correct the sitting posture and prevent health problems(e.g.,deformity of spinal column and musculoskeletal disease).Currently,most measurement systems hinder their wide applications owing to the high cost or low accuracy.In this study,a flexible sitting pressure measurement system was proposed based on a textile-based capacitive pressure sensor array in order to measure sitting pressure distribution simply and conveniently.The capacitive pressure sensor array is sandwich structure composed of a high-density sponge layer and two electrode array fabrics,which possesses high resolution(2.26 sensors/cm2),high sensitivity(0.701 kPa-1)and fast response(≤35 ms).It is worth noting that the raw materials of the sensing fabric include commercialized copper sheets and polyester yarns.The as-prepared pressure measurement system can accurately measure the pressure distribution nephogram for sitting posture analysis.The sitting pressure of 10 volunteers was measured and six types of posture were distinguished clearly.
基金RαProject supported by the National Natural Science Foundation of China(Grant No.11072242)the Research and Development Program of Science and Technology of Higher Education of Shanxi Province,China(Grant No.20121029)
文摘The expressions of the radius and the surface tension of surface of tension Rs and γs in terms of the pressure distribution for nanoscale liquid threads are of great importance for molecular dynamics (MD) simulations of the interfacial phenomena of nanoscale fluids; these two basic expressions are derived in this paper. Although these expressions were derived first in the literature[Kim B G, Lee J S, Han M H, and Park S, 2006 Nanoscale and Microscale Thermophysical Engineering, 10, 283] and used widely thereafter, the derivation is wrong both in logical structure and physical thought. In view of the importance of these basic expressions, the logic and physical mistakes appearing in that derivation are pointed out.
文摘Based on incompressible viscous fluid Navier-stokes equation and k-ε 2-equations turbulent model, an investigation on 3D turbulent flow field around four kinds of train models has been made by finite element method. From the calculation, the pressure distribution characters of now field around high-speed trains have been obtained. It is significant for strength design of the high-speed train body, for resisting wind design of the facilities beside the high-speed railways and for determining the aerodynamic force of induced air to the human body near the railways.
基金Project supported by the National Natural Science Foundation of China (Grant No:50274019) the Natural Science Foundation of Heilongjiang Province (Grant No:A200501)
文摘In this article, the governing equations for the unsteady flow of viscoelastic fluid in the eccentric annulus with the inner cylinder reciprocating axially and the expression of the pressure distribution on the wall of the inner cylinder of the annulus are established and derived, respectively, under the bipolar coordinate system. The equations and the expression are solved and calculated numerically using the finite difference method, respectively. The curves of the pressure distribution on the wall of the inner cylinder of the aqueous solution of Hydrolyzed Polyacrylamide (HPAM) are plotted and the influences of annular eccentricity, stroke, and stroke frequency on the pressure distribution are analyzed.
基金co-supported by the National Key Basic Research Program of China(No.2014CB744806)Tsinghua University Initiative Scientific Research Program(No.2015Z22003)
文摘Pressure distribution is important information for engineers during an aerodynamic design process. Pressure Distribution Oriented(PDO) optimization design has been proposed to introduce pressure distribution manipulation into traditional performance dominated optimization.In previous PDO approaches, constraints or manual manipulation have been used to obtain a desirable pressure distribution. In the present paper, a new Pressure Distribution Guided(PDG) method is developed to enable better pressure distribution manipulation while maintaining optimization efficiency. Based on the RBF-Assisted Differential Evolution(RADE) algorithm, a surrogate model is built for target pressure distribution features. By introducing individuals suggested by suboptimization on the surrogate model into the population, the direction of optimal searching can be guided. Pressure distribution expectation and aerodynamic performance improvement can be achieved at the same time. The improvements of the PDG method are illustrated by comparing its design results and efficiency on airfoil optimization test cases with those obtained using other methods. Then the PDG method is applied on a dual-aisle airplane’s inner-board wing design. A total drag reduction of 8 drag counts is achieved.
文摘For controlling dexterous prosthetic hand with a high number of active Degrees of Freedom (DOF), it is necessary to reliably extract control volitions of finger motions from the human body. In this study, a large variety of finger motions are discriminated based on the diversities of the pressure distribution produced by the mechanical actions of muscles on the forearm. The pressure distribution patterns corresponding to the motions were measured by sensor array which is composed of 32 Force Sensitive Resistor (FSR) sensors. In order to map the pressure patterns with different finger motions, a multiclass classifier was designed based on the Support Vector Machine (SVM) algorithm. The multi-subject experiments show that it is possible to identify as many as seventeen different finger motions, including individual finger motions and multi-finger grasping motions, with the accuracy above 99% in the in-session validation. Further, the cross-session validation demonstrates that the performance of the proposed method is robust for use if the FSR array is not reset. The results suggest that the proposed method has great application prospects for the control of multi-DOF dexterous hand prosthesis.
基金supported by the National Natural Science Foundation of China(Nos.91852108 and 11872230)。
文摘In the field of supercritical wing design, various principles and rules have been summarized through theoretical and experimental analyses. Compared with black-box relationships between geometry parameters and performances, quantitative physical laws about pressure distributions and performances are clearer and more beneficial to designers. With the advancement of computational fluid dynamics and computational intelligence, discovering new rules through statistical analysis on computers has become increasingly attractive and affordable. This paper proposes a novel sampling method for the statistical study on pressure distribution features and performances, so that new physical laws can be revealed. It utilizes an adaptive sampling algorithm, of which the criteria are developed based on Kullback–Leibler divergence and Euclidean distance.In this paper, the proposed method is employed to generate airfoil samples to study the relationships between the supercritical pressure distribution features and the drag divergence Mach number as well as the drag creep characteristic. Compared with conventional sampling methods, the proposed method can efficiently distribute samples in the pressure distribution feature space rather than directly sampling airfoil geometry parameters. The corresponding geometry parameters are searched and found under constraints, so that supercritical airfoil samples that are well distributed in the pressure distribution space are obtained. These samples allow statistical studies to obtain more reliable and universal aerodynamic rules that can be applied to supercritical airfoil designs.
基金This work has been supported by the National Science Fund for Distinguished Young Scholars of China(Grant No.51125019).
文摘This paper provides a novel three-dimensional meshless Galerkin for horizontal well reservoir simulation.The pressure function is approached by moving least-square method which consists of weight function,basic function and coefficient.Based on Galerkin principle and use penalty function method,the paper deduces the meshless Galerkin numerical linear equations.Cut off the pressure distribution of the horizontal section from the simulation database of horizontal well reservoir.It demonstrates that meshless Galerkin is a feasible numerical method for the horizontal well reservoir simulation.It is useful to research complex reservoir.
文摘A series of wind tunnel tests was conducted to examine how an end plate affects the pressure distributions of two wings with leading edge(LE) sweep angles of 23° and 40°. All the experiments were carried out at a midchord Reynolds number of 8×10~5, covering an angle of attack(AOA) range from -2° to 14°. Static pressure distribution measurements were acquired over the upper surfaces of the wings along three chordwise rows and one spanwise direction at the wing quarter-chord line. The results of the tests confirm that at a particular AOA, increasing the sweep angle causes a noticeable decrease in the upper-surface suction pressure. Furthermore, as the sweep angle increases, the development of a laminar separation bubble near the LEs of the wings takes place at higher AOAs. On the other hand, spanwise pressure measurements show that increasing the wing sweep angle results in forming a stronger vortex on the quarter-chord line which has lower sensitivity to AOA variation and remains substantially attached to the wing surface for higher AOAs than that can be achieved in the case of a lower sweep angle. In addition, data obtained indicate that installing an end plate further reinforces the spanwise flow over the wing surface, thus affecting the pressure distribution.
文摘The current paper presents the result of a study on determining the pressure distribution along the surface of a foil section by using measured velocity field data and the Reynolds Averaged Navier-Stokes equations. The results are compared with the measured pressure data and show its satisfaction. It is a try to find a new way to determine pressure by combining the experimental data and CFD method.
基金supported by the National Natural Science Foundation of China(Grant Nos.10972087,51125024)。
文摘In this paper the pressure distribution of the gaseous flow in a microchannel is studied via a lattice Boltzmann equation(LBE)method.With effective relaxation times and a generalized second order slip boundary condition,the LBE can be used to simulate rarefied gas flows from slip to transition regimes.The Knudsen minimum phenomena of mass flow rate in the pressure driven flow is also investigated.The effects of Knudsen number(rarefaction effect),pressure ratio and aspect ratio(compression effect)on the pressure distribution are analyzed.It is found the rarefaction effect tends to the curvature of the nonlinear pressure distribution,while the compression effect tends to enhance its nonlinearity.The combined effects lead to a local minimum of the pressure deviation.Furthermore,it is also found that the relationship between the pressure deviation and the aspect ratio follows a pow-law.
基金The present study is supported by the grant from the Natural Science Foundation of China.
文摘In the present paper,two-and three-dimensional velocity potentials generated by pulsating pressure distributions of infinite extent on the free surface of infinite-depth waters are strictly derived based on special cases of concentrated pulsating pressure.The far-field asymptotic behaviour of the potentials and the radiation conditions to be satisfied by them are discussed. It is proved in a general sense that the potentials should be composed of a forced wave component,a free wave component and a local disturbance component.The radiation condition of the forced wave component should correspond to the far-field asymptotic behaviour of the pressure distribution,Hence,the formulation of radiation conditions for the second-order diffraction potentials has theoretically become clear,The radiation conditions for two-and three-dimensional problems are explicitly given in the paper.
基金supported by the Science and Engineering Project of Communication University of China(3132016XNG1625)
文摘By analyzing the differences between binaural recording and real listening, it was deduced that there were some unrevealed auditory localization clues, and the sound pressure distribution pattern at the entrance of ear canal was probably a clue. It was proved through the listening test that the unrevealed auditory localization clues really exist with the reduction to absurdity. And the effective frequency bands of the unrevealed localization clues were in- duced and summed. The result of finite element based simulations showed that the pressure distribution at the entrance of ear canal was non-uniform, and the pattern was related to the direction of sound source. And it was proved that the sound pressure distribution pattern at the entrance of the ear canal carried the sound source direction information and could be used as an unrevealed localization clue. The frequency bands in which the sound pressure distribution patterns had significant differences between front and back sound source directions were roughly matched with the effective frequency bands of unrevealed localization clues obtained from the listening tests. To some extent, it supports the pattern could be a kind of unrevealed auditory hypothesis that the sound pressure distribution localization clues.
文摘A wind tunnel tests with different configurations,pitch and yaw angles were performed to study the wind load characteristics of the rigid model of the airship Zhiyuan-1. The rigid model was aimed to simulate a technical demonstrating stratospheric airship named Zhiyuan-1 according to the similarity principle of geometric and Reynolds number. Based on the results of wind tunnel test,the features of pressure coefficient distributions on the surface of the airship were described. It was indicated that the fins and the gondola of airship hardly have the effect on the pressure distribution on the surface of airship,but have obviously effect on the local areas near the fins and the gondola.