In the context of Industry 5.0,more emphasis is placed on human-centric smart manufacturing patterns.Product design is a vital phase of smart manufacturing,involving user engagement is an essential factor in enhancing...In the context of Industry 5.0,more emphasis is placed on human-centric smart manufacturing patterns.Product design is a vital phase of smart manufacturing,involving user engagement is an essential factor in enhancing design quality and fostering innovation.With user involvement in-depth,dynamically changing user requirements and feedback bring new problems to the design process,and the traditional linear solving process cannot perceive such variations timely,which causes hysteresis in the solution.The design solution's hysteresis affects the consensus achievement process between the designer and user,further prolonging the iteration cycle.To address this issue,a human-centric product conceptual design model is proposed for the timely translation of such variations into design solutions.In this model,design problems are formed by centering on user requirements,designer and user collaboratively solve the problems to form design solutions.Through a cycle of problem-driven,knowledgesupported,and solution evaluation,new problems are solved promptly to achieve progressive solution convergence,which clarifies the iterative evolution process and improves iterative efficiency.To verify the effectiveness of the model,a natural gas well foaming agent automatic filling device design is presented.展开更多
Retrogressive landslides in sensitive clays pose significant risks to nearby infrastructure,as natural toe erosion or localized disturbances can trigger progressive block failures.While prior studies have largely reli...Retrogressive landslides in sensitive clays pose significant risks to nearby infrastructure,as natural toe erosion or localized disturbances can trigger progressive block failures.While prior studies have largely relied on two-dimensional(2D)large-deformation analyses,such models overlook key three-dimensional(3D)failure mechanisms and variability effects.This study develops a 3D probabilistic framework by integrating the Coupled Eulerian–Lagrangian(CEL)method with random field theory to simulate retrogressive landslides in spatially variable clay.Using Monte Carlo simulations,we compare 2D and 3D random large-deformation models to evaluate failure modes,runout distances,sliding velocities,and influence zones.The 3D analyses captured more complex failure modes—such as lateral retrogression and asynchronous block mobilization across slope width.Additionally,the 3D analyses predict longer mean runout distances(13.76 vs.11.92 m),wider mean influence distance(11.35 vs.8.73 m),and higher mean sliding velocities(4.66 vs.3.94 m/s)than their 2D counterparts.Moreover,3D models exhibit lower coefficients of variation(e.g.,0.10 for runout distance)due to spatial averaging across slope width.Probabilistic hazard assessment shows that 2D models significantly underpredict near-field failure probabilities(e.g.,48.8%vs.89.9%at 12 m from the slope toe).These findings highlight the limitations of 2D analyses and the importance of multi-directional spatial variability for robust geohazard assessments.The proposed 3D framework enables more realistic prediction of landslide mobility and supports the design of safer,risk-informed infrastructure.展开更多
The moving-mean method is one of the conventional approaches for trend-extraction from a data set. It is usually applied in an empirical way. The smoothing degree of the trend depends on the selections of window lengt...The moving-mean method is one of the conventional approaches for trend-extraction from a data set. It is usually applied in an empirical way. The smoothing degree of the trend depends on the selections of window length and weighted coefficients, which are associated with the change pattern of the data. Are there any uniform criteria for determining them? The present article is a reaction to this fundamental problem. By investigating many kinds of data, the results show that: 1) Within a certain range, the more points which participate in moving-mean, the better the trend function. However, in case the window length is too long, the trend function may tend to the ordinary global mean. 2) For a given window length, what matters is the choice of weighted coefficients. As the five-point case concerned, the local-midpoint, local-mean and global-mean criteria hold. Among these three criteria, the local-mean one has the strongest adaptability, which is suggested for your usage.展开更多
Structure prediction methods have been widely used as a state-of-the-art tool for structure searches and materials discovery, leading to many theory-driven breakthroughs on discoveries of new materials. These methods ...Structure prediction methods have been widely used as a state-of-the-art tool for structure searches and materials discovery, leading to many theory-driven breakthroughs on discoveries of new materials. These methods generally involve the exploration of the potential energy surfaces of materials through various structure sampling techniques and optimization algorithms in conjunction with quantum mechanical calculations. By taking advantage of the general feature of materials potential energy surface and swarm-intelligence-based global optimization algorithms, we have developed the CALYPSO method for structure prediction, which has been widely used in fields as diverse as computational physics, chemistry, and materials science. In this review, we provide the basic theory of the CALYPSO method, placing particular emphasis on the principles of its various structure dealing methods. We also survey the current challenges faced by structure prediction methods and include an outlook on the future developments of CALYPSO in the conclusions.展开更多
Objective: The integrated method was investigated to measure Vm/Km of mouse liver glutathione S-transfer-ase (GST) activity on GSH and 7-Cl-4-nitrobenzofurazozan. Methods: Presetting concentration of one substrate twe...Objective: The integrated method was investigated to measure Vm/Km of mouse liver glutathione S-transfer-ase (GST) activity on GSH and 7-Cl-4-nitrobenzofurazozan. Methods: Presetting concentration of one substrate twenty-fold above the other's and taking maximum product absorbance Am as parameter while Km as constant, Vm/Km was obtained by nonlinear fitting of GST reaction curve to the integrated Michaelis-Menten equation In [Am/(Am -Ai)] + Ai/ ( ξ× Km ) = ( Vm/Km )×ti (1). Results: Vm/Km for GST showed slight dependence on initial substrate concentration and data range, but it was resistant to background absorbance, error in reaction origin and small deviation in presetting Km. Vm/Km was proportional to the amount of GST with upper limit higher than that by initial rate. There was close correlation between Vm/Km and initial rate of the same GST. Consistent results were obtained by this integrated method and classical initial rate method for the measurement of mouse liver GST. Conclusion: With the concentration of one substrate twenty-fold above the other's, this integrated method was reliable to measure the activity of enzyme on two substrates , and substrate concentration of the lower one close to its apparent Km was able to be used.展开更多
The control rod drive mechanism(CRDM)is an essential part of the control and safety protection system of pressurized water reactors.Current CRDM simulations are mostly performed collectively using a single method,igno...The control rod drive mechanism(CRDM)is an essential part of the control and safety protection system of pressurized water reactors.Current CRDM simulations are mostly performed collectively using a single method,ignoring the influence of multiple motion units and the differences in various features among them,which strongly affect the efficiency and accuracy of the simulations.In this study,we constructed a flow field fusion simulation method based on model features by combining key motion unit analysis and various simulation methods and then applied the method to the CRDM simulation process.CRDM performs motion unit decomposition through the structural hierarchy of function-movement-action method,and the key meta-actions are identified as the nodes in the flow field simulation.We established a fused feature-based multimethod simulation process and processed the simulation methods and data according to the features of the fluid domain space and the structural complexity to obtain the fusion simulation results.Compared to traditional simulation methods and real measurements,the simulation method provides advantages in terms of simulation efficiency and accuracy.展开更多
Recently, the research of dynamics and control of the satellite formation flying has been attracting a great deal of attentions of the researchers. The theory of the research was mainly based on Clohessy-Wiltshire'...Recently, the research of dynamics and control of the satellite formation flying has been attracting a great deal of attentions of the researchers. The theory of the research was mainly based on Clohessy-Wiltshire' s (C-W's) equations, which describe the relative motion between two satellites. But according to some special examples and qualitative analysis , neither the initial parameters nor the period of the solution of C-W' s equations accord with the actual situation, and the conservation of energy is no longer held. A new method developed from orbital element description of single satellite , named relative orbital element method ( ROEM) , was introduced. This new method, with clear physics conception and wide application range, overcomes the limitation of C-W s equation , and the periodic solution is a natural conclusion. The simplified equation of the relative motion is obtained when the eccentricity of the main satellite is small. Finally, the results of the two methods (C-W' s equation and ROEM) are compared and the limitations of C-W s equations are pointed out and explained.展开更多
As an important aspect of applications, it is discussed how to find periodic solutions for ordinary differential equations. By using the homotopy method, a global method for finding those solutions is proposed.
Three characteristic points in the deformation history of a fractured tensile specimen are selected tocalculate two values of n( n1 and n2 ) to represent the hardening ability of material during the homogeneous plas-t...Three characteristic points in the deformation history of a fractured tensile specimen are selected tocalculate two values of n( n1 and n2 ) to represent the hardening ability of material during the homogeneous plas-tic deformation and the following large plastic deformation. Experimental results obtained with mild streel andred copper show that n determined using the three-point method proposed is better to describe the hardening a-bility of material. It is therefore concluded that three-point method can be used to describe the hardening prop-erty of material during both homogeneous deformation and large plastic deformation.展开更多
In studying the diffusion-controlled adsorption kinetics of aqueous surfactant solutions at the air/solution surface by means of the maximal bubble pressure method, Fick's diffusion equation for a sphere should be...In studying the diffusion-controlled adsorption kinetics of aqueous surfactant solutions at the air/solution surface by means of the maximal bubble pressure method, Fick's diffusion equation for a sphere should be used. In this paper the equation was solved by means of Laplace transformation under different initial and boundary conditions. The dynamic surface adsorption F(t) for a surfactant solution, which was used to describe the diffusion-controlled adsorption kinetics at the solution surface, was derived. Different from the planar surface adsorption, the dynamic surface adsorption F(t) for the short time consists of two terms: one is the same as Ward-Tordai equation and the other reflects the geometric effect caused by the spherical bubble surface. This effect should not be neglected for the very small radius of the capillary. The equilibrium surface tension γeq and the dynamic surface tension γ(t) of aqueous C10E6 [CH3(CH2)9(OCH2CH2)6OH] solution at temperature 25℃ were measuredby means of Wilhelmy plate method and maximal bubble pressure method respectively. As t→ 0, the theoreticalanalysis is in good agreement with experimental results and the dependence of γ(t) on is linear.展开更多
An Inverse perturbation method is described for solving the general inverse eigenvalue problem. By taking the analysis of the rotor system as example based upon FEM, the new inverse perturbation method for structural ...An Inverse perturbation method is described for solving the general inverse eigenvalue problem. By taking the analysis of the rotor system as example based upon FEM, the new inverse perturbation method for structural design with specified low-order natural frequencies or frequency constraint bands is detailed as well as its complete theoretical basis. Moreover, formulations to calculate the inverse perturbation parameter ε and method to select the corresponding ε's value properly are also proposed. The proposed method is characterized in reducing frequency analysis and suitable for large and small structrual changes alike. Finally, several different numerical examples for inverse cigenvalue problem are discussed to illustrate the method, which show that this inverse perturbation method Is general and can be applied to other type of structure or dement.展开更多
ICSED (Improved Cluster Shade Edge Detection) algorithm and other various methods to accurately and efficiently detect edges on satellite data are presented. Error rate criterion is used to statistically evaluate the ...ICSED (Improved Cluster Shade Edge Detection) algorithm and other various methods to accurately and efficiently detect edges on satellite data are presented. Error rate criterion is used to statistically evaluate the performances of these methods in detecting oceanic features for both noise free and noise contaminated AVHRR (Advanced Very High Resolution Radiometer) IR image with Kuroshio. Also, practical experiments in detecting the eddy of Kuroshio with these methods are carried out for comparison. Results show that the ICSED algorithm has more advantages than other methods in detecting mesoscale features of ocean. Finally, the effectiveness of window size of ICSED method to oceanic features detection is quantitatively discussed.展开更多
The truncated expansion method for finding explicit and exact soliton-like solution of variable coefficient nonlinear evolution equation was described. The crucial idea of the method was first the assumption that coef...The truncated expansion method for finding explicit and exact soliton-like solution of variable coefficient nonlinear evolution equation was described. The crucial idea of the method was first the assumption that coefficients of the truncated expansion formal solution are functions of time satisfying a set of algebraic equations, and then a set of ordinary different equations of undetermined functions that can be easily integrated were obtained. The simplicity and effectiveness of the method by application to a general variable coefficient KdV-MKdV equation with three arbitrary functions of time is illustrated.展开更多
The simulation of the electromagnetic wave propagation plays an important role in predicting the performance of wireless transmission and communication systems. This research paper performs a numerical simulation usin...The simulation of the electromagnetic wave propagation plays an important role in predicting the performance of wireless transmission and communication systems. This research paper performs a numerical simulation using the finite element method (FEM) to study electromagnetic propagation through both conductive and dielectric media. The simulations are made using the COMSOL Multiphysics software which notably implements the finite element method. The microwave is produced by a Vivaldi antenna at the respective frequencies of 2.6 and 5 GHz and the propagation equation is formulated from Maxwell’s equations. The results obtained show that in the air, strong electric fields are observed in the slot and the micro-strip line for the two frequencies, they are even greater when the wave propagates in the glass and very weak for the copper. The 3D evolutions of the wave in air and glass present comparable values at equal frequencies, the curves being more regular in air (dielectric). The radiation patterns produced for air and glass are directional, with a large main lobe, which is narrower at 5 GHz. For copper, the wave propagation is quite uniform in space, and the radiation patterns show two main lobes with a much larger size at 2.6 GHz than at 5 GHz. The propagation medium would therefore influence the range of values of the gain of the antenna.展开更多
The method of boundary layer with multiple scales and computer algebra were applied to study the asymptotic behavior of solution of boundary value problems for a class of system of nonlinear differential equations . T...The method of boundary layer with multiple scales and computer algebra were applied to study the asymptotic behavior of solution of boundary value problems for a class of system of nonlinear differential equations . The asymptotic expansions of solution were constructed. The remainders were estimated. And an example was analysed. It provides a new foreground for the application of the method of boundary layer with multiple scales .展开更多
This study proposed the newly-designed Pelagic and demersal trawls for the fishing vessels operating in Cameroonian waters in pelagic and demersal fishing grounds. The engineering performances of both trawls were inve...This study proposed the newly-designed Pelagic and demersal trawls for the fishing vessels operating in Cameroonian waters in pelagic and demersal fishing grounds. The engineering performances of both trawls were investigated using physical modelling method and analytical method based on the predicted equations. In a flume tank, a series of physical model tests based on Tauti’s law were performed to investigate the hydrodynamic and geometrical performances of both trawls and to assess the applicability of the analytical methods based on predicted equations. The results showed that in model scale, the working towing speed and door spread for the pelagic trawl were 3.5 knots and 1.85 m, respectively, and for the bottom trawl net they were 4.0 knots and 1.8 m. At that speed and door spread, the drag force, net opening height, and wing-end spread of the pelagic model trawl were 36.73 N, 0.89 m, and 0.86 m, respectively, and the swept area was 0.76 m<sup>2</sup>. Bottom trawl speed and door spread were 30.43 N, 0.38 m, and 0.45 m, respectively, and the swept area was 0.25 m<sup>2</sup>. The maximum difference between the experimental and analytical results of hydrodynamic performances was less than 56.22% and 41.45%, respectively, for pelagic and bottom trawls, the results of the geometrical performances obtained using predicted equations were close to the experimental results in the flume tank with a maximum relative error less than 12.85%. The newly developed pelagic and bottom trawls had advanced engineering performance for high catch efficiency and selectivity and could be used in commercial fishing operations in Cameroonian waters.展开更多
A cascade profile design method was proposed using the aerodynamic load and blade thickness distribution as the design constraints, which were correspondent to the demands from the aerodynamic characteristics and the ...A cascade profile design method was proposed using the aerodynamic load and blade thickness distribution as the design constraints, which were correspondent to the demands from the aerodynamic characteristics and the blade strength. These constraints,together with all the other boundary conditions , were involved in the stationary conditions ofa variational principle , in which the angle-function was employed as the unknown function.The angle-function ( i. e. , the circumferential angular coordinate) was defined in the image plane composed of the stream function coordinate ( circumferential direction ) and streamline coordinate. The solution domain, i.e., the blade-to-blade passage, was transformed into a square in the image plane, while the blade contour was projected to a straight line ; thus, the difficulty of the unknown blade geometry was avoided. The finite element method was employed to establish the calculation code. Applications show that this method can satisfy the design requests on the blade profile from both aerodynamic and strength respects. In addition, quite different from the most inverse-problem approaches that often encounter difficulties in the convergence of iteration, the present method shows a stable and fast convergence tendency. This will be significant for engineering applications.展开更多
Linux-based Platform for Open Architecture Controller ( POAC ), a new open architecture controller and its modular developing method are discussed. POAC divides the application software of controller into the developi...Linux-based Platform for Open Architecture Controller ( POAC ), a new open architecture controller and its modular developing method are discussed. POAC divides the application software of controller into the developing system and the application system. In the developing system, PAOC abstracts a series of function modules with unified data interface and function interface. In the application system, POAC defines the model of the architecture module, realizing the interoperability and interchangeability between the architecture modules. The modular developing method entities the users to make up an application system with some architecture modules, which consist of a set of function modules. The modular developing method decreases the developing time from the standard of controller architecture to the product.展开更多
This work deals with a description of an elastic analysis of eolic blade （preprocessing, processing and post-processing stages）. The eolic blade geometry is approximated by flat finite elements in which the membrane...This work deals with a description of an elastic analysis of eolic blade （preprocessing, processing and post-processing stages）. The eolic blade geometry is approximated by flat finite elements in which the membrane effects are evaluated using the FF （free formulation） finite element and the flexure effects are calculated using DKT （discrete shear triangle） finite element. The pre-processing stage is implemented using OpenGL library, to provide the graphical construction for geometry, mesh orientation, and other requirements of the finite element model. For the processing stage is built a specific dll （dynamic link library） library implemented in C＋＋ language for the FF and DKT elements analysis. The post-processing stage has been built using specific dialogs to present all results in the graphic interface, where the static displacements of the eolic blade model are shown.展开更多
Some basic problems on the level set methods were discussed, such as the method used to preserve the distance junction , the existence and uniqueness of solution for the level set equations. The main contribution is t...Some basic problems on the level set methods were discussed, such as the method used to preserve the distance junction , the existence and uniqueness of solution for the level set equations. The main contribution is to prove that in a neighborhood of the initial zero level set, the level set equations with the restriction of the distance function have a unique solution, which must be the signed distance function with respect to the evolving surface. Some skillful approaches were used: Noticing that any solution for the original equation was a distance function, the original level set equations were transformed into a simpler alternative form. Moreover, since the new system was not a classical one, the system was transformed into an ordinary one, for which the implicit function method was adopted.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.52405285)the Sichuan University Young Teachers'Capacity Improvement Program in Science and Technology Innovation(Grant No.2024SCUQJTX026)Sichuan Provincial Engineering Technology Research Center of Broadband Electronics Intelligent Manufacturing(Grant No.BEIM2022A001)。
文摘In the context of Industry 5.0,more emphasis is placed on human-centric smart manufacturing patterns.Product design is a vital phase of smart manufacturing,involving user engagement is an essential factor in enhancing design quality and fostering innovation.With user involvement in-depth,dynamically changing user requirements and feedback bring new problems to the design process,and the traditional linear solving process cannot perceive such variations timely,which causes hysteresis in the solution.The design solution's hysteresis affects the consensus achievement process between the designer and user,further prolonging the iteration cycle.To address this issue,a human-centric product conceptual design model is proposed for the timely translation of such variations into design solutions.In this model,design problems are formed by centering on user requirements,designer and user collaboratively solve the problems to form design solutions.Through a cycle of problem-driven,knowledgesupported,and solution evaluation,new problems are solved promptly to achieve progressive solution convergence,which clarifies the iterative evolution process and improves iterative efficiency.To verify the effectiveness of the model,a natural gas well foaming agent automatic filling device design is presented.
基金supported by the National Key Research and Development Program of China(No.2024YFC2815400)the European Commission(Nos.HORIZON MSCA-2024-PF-01 and 101200637)+2 种基金the Opening Fund of the State Key Laboratory of Water Resources Engineering and Management at Wuhan University(No.2024SGG07)the Shandong Provincial Natural Science Foundation(No.ZR2025MS647)the Sand Hazards and Opportunities for Resilience,Energy,and Sustainability(SHORES)Center,funded by Tamkeen under the NYUAD Research Institute Award CG013.
文摘Retrogressive landslides in sensitive clays pose significant risks to nearby infrastructure,as natural toe erosion or localized disturbances can trigger progressive block failures.While prior studies have largely relied on two-dimensional(2D)large-deformation analyses,such models overlook key three-dimensional(3D)failure mechanisms and variability effects.This study develops a 3D probabilistic framework by integrating the Coupled Eulerian–Lagrangian(CEL)method with random field theory to simulate retrogressive landslides in spatially variable clay.Using Monte Carlo simulations,we compare 2D and 3D random large-deformation models to evaluate failure modes,runout distances,sliding velocities,and influence zones.The 3D analyses captured more complex failure modes—such as lateral retrogression and asynchronous block mobilization across slope width.Additionally,the 3D analyses predict longer mean runout distances(13.76 vs.11.92 m),wider mean influence distance(11.35 vs.8.73 m),and higher mean sliding velocities(4.66 vs.3.94 m/s)than their 2D counterparts.Moreover,3D models exhibit lower coefficients of variation(e.g.,0.10 for runout distance)due to spatial averaging across slope width.Probabilistic hazard assessment shows that 2D models significantly underpredict near-field failure probabilities(e.g.,48.8%vs.89.9%at 12 m from the slope toe).These findings highlight the limitations of 2D analyses and the importance of multi-directional spatial variability for robust geohazard assessments.The proposed 3D framework enables more realistic prediction of landslide mobility and supports the design of safer,risk-informed infrastructure.
文摘The moving-mean method is one of the conventional approaches for trend-extraction from a data set. It is usually applied in an empirical way. The smoothing degree of the trend depends on the selections of window length and weighted coefficients, which are associated with the change pattern of the data. Are there any uniform criteria for determining them? The present article is a reaction to this fundamental problem. By investigating many kinds of data, the results show that: 1) Within a certain range, the more points which participate in moving-mean, the better the trend function. However, in case the window length is too long, the trend function may tend to the ordinary global mean. 2) For a given window length, what matters is the choice of weighted coefficients. As the five-point case concerned, the local-midpoint, local-mean and global-mean criteria hold. Among these three criteria, the local-mean one has the strongest adaptability, which is suggested for your usage.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11534003 and 11604117)the National Key Research and Development Program of China(Grant No.2016YFB0201201)+1 种基金the Program for JLU Science and Technology Innovative Research Team(JLUSTIRT)of Chinathe Science Challenge Project of China(Grant No.TZ2016001)
文摘Structure prediction methods have been widely used as a state-of-the-art tool for structure searches and materials discovery, leading to many theory-driven breakthroughs on discoveries of new materials. These methods generally involve the exploration of the potential energy surfaces of materials through various structure sampling techniques and optimization algorithms in conjunction with quantum mechanical calculations. By taking advantage of the general feature of materials potential energy surface and swarm-intelligence-based global optimization algorithms, we have developed the CALYPSO method for structure prediction, which has been widely used in fields as diverse as computational physics, chemistry, and materials science. In this review, we provide the basic theory of the CALYPSO method, placing particular emphasis on the principles of its various structure dealing methods. We also survey the current challenges faced by structure prediction methods and include an outlook on the future developments of CALYPSO in the conclusions.
基金National Natural Science Foundation of China (No.30200266)
文摘Objective: The integrated method was investigated to measure Vm/Km of mouse liver glutathione S-transfer-ase (GST) activity on GSH and 7-Cl-4-nitrobenzofurazozan. Methods: Presetting concentration of one substrate twenty-fold above the other's and taking maximum product absorbance Am as parameter while Km as constant, Vm/Km was obtained by nonlinear fitting of GST reaction curve to the integrated Michaelis-Menten equation In [Am/(Am -Ai)] + Ai/ ( ξ× Km ) = ( Vm/Km )×ti (1). Results: Vm/Km for GST showed slight dependence on initial substrate concentration and data range, but it was resistant to background absorbance, error in reaction origin and small deviation in presetting Km. Vm/Km was proportional to the amount of GST with upper limit higher than that by initial rate. There was close correlation between Vm/Km and initial rate of the same GST. Consistent results were obtained by this integrated method and classical initial rate method for the measurement of mouse liver GST. Conclusion: With the concentration of one substrate twenty-fold above the other's, this integrated method was reliable to measure the activity of enzyme on two substrates , and substrate concentration of the lower one close to its apparent Km was able to be used.
基金supported by the National Natural Science Foundation of China (No. 52075350)the Special City School Strategic Cooperation Project of Sichuan University and Zigong (No.2021CDZG-3)
文摘The control rod drive mechanism(CRDM)is an essential part of the control and safety protection system of pressurized water reactors.Current CRDM simulations are mostly performed collectively using a single method,ignoring the influence of multiple motion units and the differences in various features among them,which strongly affect the efficiency and accuracy of the simulations.In this study,we constructed a flow field fusion simulation method based on model features by combining key motion unit analysis and various simulation methods and then applied the method to the CRDM simulation process.CRDM performs motion unit decomposition through the structural hierarchy of function-movement-action method,and the key meta-actions are identified as the nodes in the flow field simulation.We established a fused feature-based multimethod simulation process and processed the simulation methods and data according to the features of the fluid domain space and the structural complexity to obtain the fusion simulation results.Compared to traditional simulation methods and real measurements,the simulation method provides advantages in terms of simulation efficiency and accuracy.
基金Foundation items: the National Natural Science Foundation of China (10202008) the Post Doctoral Science Foundation of China ((2001)31)
文摘Recently, the research of dynamics and control of the satellite formation flying has been attracting a great deal of attentions of the researchers. The theory of the research was mainly based on Clohessy-Wiltshire' s (C-W's) equations, which describe the relative motion between two satellites. But according to some special examples and qualitative analysis , neither the initial parameters nor the period of the solution of C-W' s equations accord with the actual situation, and the conservation of energy is no longer held. A new method developed from orbital element description of single satellite , named relative orbital element method ( ROEM) , was introduced. This new method, with clear physics conception and wide application range, overcomes the limitation of C-W s equation , and the periodic solution is a natural conclusion. The simplified equation of the relative motion is obtained when the eccentricity of the main satellite is small. Finally, the results of the two methods (C-W' s equation and ROEM) are compared and the limitations of C-W s equations are pointed out and explained.
文摘As an important aspect of applications, it is discussed how to find periodic solutions for ordinary differential equations. By using the homotopy method, a global method for finding those solutions is proposed.
文摘Three characteristic points in the deformation history of a fractured tensile specimen are selected tocalculate two values of n( n1 and n2 ) to represent the hardening ability of material during the homogeneous plas-tic deformation and the following large plastic deformation. Experimental results obtained with mild streel andred copper show that n determined using the three-point method proposed is better to describe the hardening a-bility of material. It is therefore concluded that three-point method can be used to describe the hardening prop-erty of material during both homogeneous deformation and large plastic deformation.
基金Supported by the Scientific Research Foundation of the State Education Ministry for the Returned Overseas Chinese Scholars (D4200111).
文摘In studying the diffusion-controlled adsorption kinetics of aqueous surfactant solutions at the air/solution surface by means of the maximal bubble pressure method, Fick's diffusion equation for a sphere should be used. In this paper the equation was solved by means of Laplace transformation under different initial and boundary conditions. The dynamic surface adsorption F(t) for a surfactant solution, which was used to describe the diffusion-controlled adsorption kinetics at the solution surface, was derived. Different from the planar surface adsorption, the dynamic surface adsorption F(t) for the short time consists of two terms: one is the same as Ward-Tordai equation and the other reflects the geometric effect caused by the spherical bubble surface. This effect should not be neglected for the very small radius of the capillary. The equilibrium surface tension γeq and the dynamic surface tension γ(t) of aqueous C10E6 [CH3(CH2)9(OCH2CH2)6OH] solution at temperature 25℃ were measuredby means of Wilhelmy plate method and maximal bubble pressure method respectively. As t→ 0, the theoreticalanalysis is in good agreement with experimental results and the dependence of γ(t) on is linear.
基金This research is supported by China National Natural Science Foundation (CNNSF), Research Grant No. 50128504
文摘An Inverse perturbation method is described for solving the general inverse eigenvalue problem. By taking the analysis of the rotor system as example based upon FEM, the new inverse perturbation method for structural design with specified low-order natural frequencies or frequency constraint bands is detailed as well as its complete theoretical basis. Moreover, formulations to calculate the inverse perturbation parameter ε and method to select the corresponding ε's value properly are also proposed. The proposed method is characterized in reducing frequency analysis and suitable for large and small structrual changes alike. Finally, several different numerical examples for inverse cigenvalue problem are discussed to illustrate the method, which show that this inverse perturbation method Is general and can be applied to other type of structure or dement.
文摘ICSED (Improved Cluster Shade Edge Detection) algorithm and other various methods to accurately and efficiently detect edges on satellite data are presented. Error rate criterion is used to statistically evaluate the performances of these methods in detecting oceanic features for both noise free and noise contaminated AVHRR (Advanced Very High Resolution Radiometer) IR image with Kuroshio. Also, practical experiments in detecting the eddy of Kuroshio with these methods are carried out for comparison. Results show that the ICSED algorithm has more advantages than other methods in detecting mesoscale features of ocean. Finally, the effectiveness of window size of ICSED method to oceanic features detection is quantitatively discussed.
基金the Natural Science Foundation of Zhejiang Province of China (100039)
文摘The truncated expansion method for finding explicit and exact soliton-like solution of variable coefficient nonlinear evolution equation was described. The crucial idea of the method was first the assumption that coefficients of the truncated expansion formal solution are functions of time satisfying a set of algebraic equations, and then a set of ordinary different equations of undetermined functions that can be easily integrated were obtained. The simplicity and effectiveness of the method by application to a general variable coefficient KdV-MKdV equation with three arbitrary functions of time is illustrated.
文摘The simulation of the electromagnetic wave propagation plays an important role in predicting the performance of wireless transmission and communication systems. This research paper performs a numerical simulation using the finite element method (FEM) to study electromagnetic propagation through both conductive and dielectric media. The simulations are made using the COMSOL Multiphysics software which notably implements the finite element method. The microwave is produced by a Vivaldi antenna at the respective frequencies of 2.6 and 5 GHz and the propagation equation is formulated from Maxwell’s equations. The results obtained show that in the air, strong electric fields are observed in the slot and the micro-strip line for the two frequencies, they are even greater when the wave propagates in the glass and very weak for the copper. The 3D evolutions of the wave in air and glass present comparable values at equal frequencies, the curves being more regular in air (dielectric). The radiation patterns produced for air and glass are directional, with a large main lobe, which is narrower at 5 GHz. For copper, the wave propagation is quite uniform in space, and the radiation patterns show two main lobes with a much larger size at 2.6 GHz than at 5 GHz. The propagation medium would therefore influence the range of values of the gain of the antenna.
文摘The method of boundary layer with multiple scales and computer algebra were applied to study the asymptotic behavior of solution of boundary value problems for a class of system of nonlinear differential equations . The asymptotic expansions of solution were constructed. The remainders were estimated. And an example was analysed. It provides a new foreground for the application of the method of boundary layer with multiple scales .
文摘This study proposed the newly-designed Pelagic and demersal trawls for the fishing vessels operating in Cameroonian waters in pelagic and demersal fishing grounds. The engineering performances of both trawls were investigated using physical modelling method and analytical method based on the predicted equations. In a flume tank, a series of physical model tests based on Tauti’s law were performed to investigate the hydrodynamic and geometrical performances of both trawls and to assess the applicability of the analytical methods based on predicted equations. The results showed that in model scale, the working towing speed and door spread for the pelagic trawl were 3.5 knots and 1.85 m, respectively, and for the bottom trawl net they were 4.0 knots and 1.8 m. At that speed and door spread, the drag force, net opening height, and wing-end spread of the pelagic model trawl were 36.73 N, 0.89 m, and 0.86 m, respectively, and the swept area was 0.76 m<sup>2</sup>. Bottom trawl speed and door spread were 30.43 N, 0.38 m, and 0.45 m, respectively, and the swept area was 0.25 m<sup>2</sup>. The maximum difference between the experimental and analytical results of hydrodynamic performances was less than 56.22% and 41.45%, respectively, for pelagic and bottom trawls, the results of the geometrical performances obtained using predicted equations were close to the experimental results in the flume tank with a maximum relative error less than 12.85%. The newly developed pelagic and bottom trawls had advanced engineering performance for high catch efficiency and selectivity and could be used in commercial fishing operations in Cameroonian waters.
基金Foundation items: the National Natural Science Foundation of China (50136030) the Shanghai Major Subject Item: Power Source Island System Research
文摘A cascade profile design method was proposed using the aerodynamic load and blade thickness distribution as the design constraints, which were correspondent to the demands from the aerodynamic characteristics and the blade strength. These constraints,together with all the other boundary conditions , were involved in the stationary conditions ofa variational principle , in which the angle-function was employed as the unknown function.The angle-function ( i. e. , the circumferential angular coordinate) was defined in the image plane composed of the stream function coordinate ( circumferential direction ) and streamline coordinate. The solution domain, i.e., the blade-to-blade passage, was transformed into a square in the image plane, while the blade contour was projected to a straight line ; thus, the difficulty of the unknown blade geometry was avoided. The finite element method was employed to establish the calculation code. Applications show that this method can satisfy the design requests on the blade profile from both aerodynamic and strength respects. In addition, quite different from the most inverse-problem approaches that often encounter difficulties in the convergence of iteration, the present method shows a stable and fast convergence tendency. This will be significant for engineering applications.
基金Shanghai Science and Technology Development Foundation (995107017)
文摘Linux-based Platform for Open Architecture Controller ( POAC ), a new open architecture controller and its modular developing method are discussed. POAC divides the application software of controller into the developing system and the application system. In the developing system, PAOC abstracts a series of function modules with unified data interface and function interface. In the application system, POAC defines the model of the architecture module, realizing the interoperability and interchangeability between the architecture modules. The modular developing method entities the users to make up an application system with some architecture modules, which consist of a set of function modules. The modular developing method decreases the developing time from the standard of controller architecture to the product.
文摘This work deals with a description of an elastic analysis of eolic blade （preprocessing, processing and post-processing stages）. The eolic blade geometry is approximated by flat finite elements in which the membrane effects are evaluated using the FF （free formulation） finite element and the flexure effects are calculated using DKT （discrete shear triangle） finite element. The pre-processing stage is implemented using OpenGL library, to provide the graphical construction for geometry, mesh orientation, and other requirements of the finite element model. For the processing stage is built a specific dll （dynamic link library） library implemented in C＋＋ language for the FF and DKT elements analysis. The post-processing stage has been built using specific dialogs to present all results in the graphic interface, where the static displacements of the eolic blade model are shown.
基金the National Natural Science Foundation of China (6001161942, 60203003)
文摘Some basic problems on the level set methods were discussed, such as the method used to preserve the distance junction , the existence and uniqueness of solution for the level set equations. The main contribution is to prove that in a neighborhood of the initial zero level set, the level set equations with the restriction of the distance function have a unique solution, which must be the signed distance function with respect to the evolving surface. Some skillful approaches were used: Noticing that any solution for the original equation was a distance function, the original level set equations were transformed into a simpler alternative form. Moreover, since the new system was not a classical one, the system was transformed into an ordinary one, for which the implicit function method was adopted.
