WT5 'BZThis paper presents an unsteady and nonlinear wake model based on th e widely used Peters He finite state dynamic wake model with improvements. The swirl component in the tip trace plane (TTP) can be pr...WT5 'BZThis paper presents an unsteady and nonlinear wake model based on th e widely used Peters He finite state dynamic wake model with improvements. The swirl component in the tip trace plane (TTP) can be predicted, nonlinear items are added into the linear theory, and the old small angle assumption use d in matrix prediction is removed. All of these enha ncements are aimed at the low speed flight phase and formulations for the induce d velocity field just in the TTP frame are derived. The corresponding FORTRAN pr ogram is tested and optimized for the real time applications on PCs.展开更多
The cable-strut structural system is statically and kinematically indeterminate. The initial pre-stress is a key factor for determining the shape and load carrying capacity. A new numerical algorithm is presented here...The cable-strut structural system is statically and kinematically indeterminate. The initial pre-stress is a key factor for determining the shape and load carrying capacity. A new numerical algorithm is presented herein for the initial pre-stress finding procedure of complete cable-strut assembly. This method is based on the linear adjustment theory and does not take into account the material behavior. By using this method,the initial pre-stress of the multi self-stress modes can be found easily and the cal-culation process is simplified and efficient also. Finally,the initial pre-stress and structural performances of a particular Levy cable dome are analyzed comprehensively. The algorithm has proven to be efficient and correct,and the numerical results are valuable for practical design of Levy cable dome.展开更多
In designing the human comfort index (CI) used in Guangzhou, a Gaussian curve was adopted as the fundamental profile to develop a traw hat?model of comfort index. The model projects low or high temperatures into low i...In designing the human comfort index (CI) used in Guangzhou, a Gaussian curve was adopted as the fundamental profile to develop a traw hat?model of comfort index. The model projects low or high temperatures into low index values and the moderate temperatures into high index values. Air temperature was chosen as a basic factor in the model. Other factors such as humidity, sunshine and wind speed were introduced by considering them as temperature departures to an equivalent apparent temperature (EAT). Since the index is a relative index, 25C was chosen as an ideal apparent temperature (the most comfortable state) and a maximum CI value of 100 was assigned at this temperature. While in other circumstances, the index would be lower than 100. By utilizing this model, the daily comfort index values had been calculated for Guangzhou city for 1998-1999, using mean temperature, mean humidity, mean wind speed and total hours of sunshine. Results show that the new model was reasonable and practicable. Not only could it reflect the monthly variation of human comfort in Guangzhou, but also was sensitive to short-term changes of weather conditions.展开更多
A new finite element model for single-layered strand was investigated for accurate and efficient mechanical behavior analysis.Mathematical model was created by sectional path-nodes sweeping and dynamic node-beam mappi...A new finite element model for single-layered strand was investigated for accurate and efficient mechanical behavior analysis.Mathematical model was created by sectional path-nodes sweeping and dynamic node-beam mapping.Geometric relations between nodes in center core wire and helical wires were deduced in tension and bending incorporating material elasticity theory and deformation geometrical compatibility.Based on Timoshenko beam theory,strand of a pitch length was modeled with specific material,geometric parameters and synthesized constraint equations defined in ANSYS software,and predetermined load cases were performed.The obtained results show that discrepancies between suggested method and Costello theory do not exceed 1.51% in tension and 6.21% in bending,which verifies the correctness and accuracy of the suggested finite element model in predicting mechanical behavior of single-layered wire strand.展开更多
Tunnel water inrush is one of the common geological disasters in the underground engineering construction.In order to effectively evaluate and control the occurrence of water inrush,the risk assessment model of tunnel...Tunnel water inrush is one of the common geological disasters in the underground engineering construction.In order to effectively evaluate and control the occurrence of water inrush,the risk assessment model of tunnel water inrush was proposed based on improved attribute mathematical theory.The trigonometric functions were adopted to optimize the attribute mathematical theory,avoiding the influence of mutation points and linear variation zones in traditional linear measurement functions on the accuracy of the model.Based on comprehensive analysis of various factors,five parameters were selected as the evaluation indicators for the model,including tunnel head pressure,permeability coefficient of surrounding rock,crushing degree of surrounding rock,relative angle of joint plane and tunnel section size,under the principle of dimension rationality,independence,directness and quantification.The indicator classifications were determined.The links among measured data were analyzed in detail,and the objective weight of each indicator was determined by using similar weight method.Thereby the tunnel water inrush risk assessment model is established and applied in four target segments of two different tunnels in engineering.The evaluation results and the actual excavation data agree well,which indicates that the model is of high credibility and feasibility.展开更多
The conservation laws of the Levi equation are presented.Two types of symmetry of the Levi equationhierarchy are deduced.Further it is proved that these symmetries construct an infinite-dimensional Lie algebra.
This article describes some of the common modeling method on compressor： black-box model, theoretical model, hybrid model and so on. It compares them, pointing out its advantages and disadvantages. In order to improv...This article describes some of the common modeling method on compressor： black-box model, theoretical model, hybrid model and so on. It compares them, pointing out its advantages and disadvantages. In order to improve the design of the compressor and its performance, this paper proposes a new modeling theory. In this model, when you make the curve fitting between multiple variables, variables can be divided into many groups. Firstly, looking for the relationship between the variables in groups, and then you can find the relationship between aggregated group.展开更多
This paper presents the research on the laws of systematic-parameter dependent variation in the vibration amplitude of drum-brake limit cycle oscillations (LCO). We established a two-degree non-linear dynamic model to...This paper presents the research on the laws of systematic-parameter dependent variation in the vibration amplitude of drum-brake limit cycle oscillations (LCO). We established a two-degree non-linear dynamic model to describe the low-frequency vibration of the drum brake, applied the centre manifold theory to simplify the system, and obtained the LCO amplitude by calculating the normal form of the simplified system at the Hopf bifurcation point. It is indicated that when the friction coefficient is smaller than the friction coefficient at the bifurcation point, the amplitude decreases; whereas with a friction coefficient larger than the friction coefficient of bifurcation point, LCO occurs. The results suggest that it is applicable to suppress the LCO amplitude by changing systematic parameters, and thus improve the safety and ride comfort when applying brake. These findings can be applied to guiding the design of drum brakes.展开更多
Variable pump driving variable motor(VPDVM) is the future development trend of the hydraulic transmission of an unmanned ground vehicle(UGV).VPDVM is a dual-input single-output nonlinear system with coupling,which is ...Variable pump driving variable motor(VPDVM) is the future development trend of the hydraulic transmission of an unmanned ground vehicle(UGV).VPDVM is a dual-input single-output nonlinear system with coupling,which is difficult to control.High pressure automatic variables bang-bang(HABB) was proposed to achieve the desired motor speed.First,the VPDVM nonlinear mathematic model was introduced,then linearized by feedback linearization theory,and the zero-dynamic stability was proved.The HABB control algorithm was proposed for VPDVM,in which the variable motor was controlled by high pressure automatic variables(HA) and the variable pump was controlled by bang-bang.Finally,simulation of VPDVM controlled by HABB was developed.Simulation results demonstrate the HABB can implement the desired motor speed rapidly and has strong robustness against the variations of desired motor speed,load and pump speed.展开更多
Chaos is a similar and random process which is very sensitive to initial value in deterministic system. It is a performance of nonlinear dynamical system with built-in randomness. Combined with the advantages and disa...Chaos is a similar and random process which is very sensitive to initial value in deterministic system. It is a performance of nonlinear dynamical system with built-in randomness. Combined with the advantages and disadvantages of the present chaos encryption model, the paper proposes a chaotic stream cipher model based on chaos theory, which not only overcomes finite precision effect, but also improves the randomness of chaotic system and output sequence. The Sequence cycle theory generated by the algorithm can reach more than 10600 at least, which completely satisfies the actual application requirements of stream cipher system.展开更多
Soliton theory plays an important role in nonlinear physics.The elastic interaction among solitons is oneof the most important properties for integrable systems.In this Letter, an elastic vortex interaction model is p...Soliton theory plays an important role in nonlinear physics.The elastic interaction among solitons is oneof the most important properties for integrable systems.In this Letter, an elastic vortex interaction model is proposed.It is found that the momenta, vortex momenta and the energies of every one vortex and the interaction energies of everytwo vortices are conserved.展开更多
We show the existence and multiplicity of solutions to degenerate p(x)-Laplace equations with Leray-Lions type operators using direct methods and critical point theories in Calculus of Variations and prove the uniquen...We show the existence and multiplicity of solutions to degenerate p(x)-Laplace equations with Leray-Lions type operators using direct methods and critical point theories in Calculus of Variations and prove the uniqueness and nonnegativeness of solutions when the principal operator is monotone and the nonlinearity is nonincreasing. Our operator is of the most general form containing all previous ones and we also weaken assumptions on the operator and the nonlinearity to get the above results. Moreover, we do not impose the restricted condition on p(x) and the uniform monotonicity of the operator to show the existence of three distinct solutions.展开更多
文摘WT5 'BZThis paper presents an unsteady and nonlinear wake model based on th e widely used Peters He finite state dynamic wake model with improvements. The swirl component in the tip trace plane (TTP) can be predicted, nonlinear items are added into the linear theory, and the old small angle assumption use d in matrix prediction is removed. All of these enha ncements are aimed at the low speed flight phase and formulations for the induce d velocity field just in the TTP frame are derived. The corresponding FORTRAN pr ogram is tested and optimized for the real time applications on PCs.
基金Project (No.863-705-210) supported by the Hi-Tech Research and Development Program (863) of China
文摘The cable-strut structural system is statically and kinematically indeterminate. The initial pre-stress is a key factor for determining the shape and load carrying capacity. A new numerical algorithm is presented herein for the initial pre-stress finding procedure of complete cable-strut assembly. This method is based on the linear adjustment theory and does not take into account the material behavior. By using this method,the initial pre-stress of the multi self-stress modes can be found easily and the cal-culation process is simplified and efficient also. Finally,the initial pre-stress and structural performances of a particular Levy cable dome are analyzed comprehensively. The algorithm has proven to be efficient and correct,and the numerical results are valuable for practical design of Levy cable dome.
文摘In designing the human comfort index (CI) used in Guangzhou, a Gaussian curve was adopted as the fundamental profile to develop a traw hat?model of comfort index. The model projects low or high temperatures into low index values and the moderate temperatures into high index values. Air temperature was chosen as a basic factor in the model. Other factors such as humidity, sunshine and wind speed were introduced by considering them as temperature departures to an equivalent apparent temperature (EAT). Since the index is a relative index, 25C was chosen as an ideal apparent temperature (the most comfortable state) and a maximum CI value of 100 was assigned at this temperature. While in other circumstances, the index would be lower than 100. By utilizing this model, the daily comfort index values had been calculated for Guangzhou city for 1998-1999, using mean temperature, mean humidity, mean wind speed and total hours of sunshine. Results show that the new model was reasonable and practicable. Not only could it reflect the monthly variation of human comfort in Guangzhou, but also was sensitive to short-term changes of weather conditions.
基金Project(2009J007)supported by Science and Technology Department of Railway Ministry of ChinaProject(U1134203)supported by Joint Fund of High-speed Railway Fundamental Research,China
文摘A new finite element model for single-layered strand was investigated for accurate and efficient mechanical behavior analysis.Mathematical model was created by sectional path-nodes sweeping and dynamic node-beam mapping.Geometric relations between nodes in center core wire and helical wires were deduced in tension and bending incorporating material elasticity theory and deformation geometrical compatibility.Based on Timoshenko beam theory,strand of a pitch length was modeled with specific material,geometric parameters and synthesized constraint equations defined in ANSYS software,and predetermined load cases were performed.The obtained results show that discrepancies between suggested method and Costello theory do not exceed 1.51% in tension and 6.21% in bending,which verifies the correctness and accuracy of the suggested finite element model in predicting mechanical behavior of single-layered wire strand.
基金Project(2013CB036004) supported by National Basic Research Program(973)of ChinaProject(51378510) supported by National Natural Science Foundation of China
文摘Tunnel water inrush is one of the common geological disasters in the underground engineering construction.In order to effectively evaluate and control the occurrence of water inrush,the risk assessment model of tunnel water inrush was proposed based on improved attribute mathematical theory.The trigonometric functions were adopted to optimize the attribute mathematical theory,avoiding the influence of mutation points and linear variation zones in traditional linear measurement functions on the accuracy of the model.Based on comprehensive analysis of various factors,five parameters were selected as the evaluation indicators for the model,including tunnel head pressure,permeability coefficient of surrounding rock,crushing degree of surrounding rock,relative angle of joint plane and tunnel section size,under the principle of dimension rationality,independence,directness and quantification.The indicator classifications were determined.The links among measured data were analyzed in detail,and the objective weight of each indicator was determined by using similar weight method.Thereby the tunnel water inrush risk assessment model is established and applied in four target segments of two different tunnels in engineering.The evaluation results and the actual excavation data agree well,which indicates that the model is of high credibility and feasibility.
基金National Natural Science Foundation of China under Grant Nos.10871165 and 10671121
文摘The conservation laws of the Levi equation are presented.Two types of symmetry of the Levi equationhierarchy are deduced.Further it is proved that these symmetries construct an infinite-dimensional Lie algebra.
文摘This article describes some of the common modeling method on compressor： black-box model, theoretical model, hybrid model and so on. It compares them, pointing out its advantages and disadvantages. In order to improve the design of the compressor and its performance, this paper proposes a new modeling theory. In this model, when you make the curve fitting between multiple variables, variables can be divided into many groups. Firstly, looking for the relationship between the variables in groups, and then you can find the relationship between aggregated group.
基金the Natural Science Foundation of China (No. 50075029)
文摘This paper presents the research on the laws of systematic-parameter dependent variation in the vibration amplitude of drum-brake limit cycle oscillations (LCO). We established a two-degree non-linear dynamic model to describe the low-frequency vibration of the drum brake, applied the centre manifold theory to simplify the system, and obtained the LCO amplitude by calculating the normal form of the simplified system at the Hopf bifurcation point. It is indicated that when the friction coefficient is smaller than the friction coefficient at the bifurcation point, the amplitude decreases; whereas with a friction coefficient larger than the friction coefficient of bifurcation point, LCO occurs. The results suggest that it is applicable to suppress the LCO amplitude by changing systematic parameters, and thus improve the safety and ride comfort when applying brake. These findings can be applied to guiding the design of drum brakes.
基金Project(51375029)supported by the National Natural Science Foundation of ChinaProject(20091102120038)supported by Specialized Research Fund for Doctoral Program of Higher Education of China
文摘Variable pump driving variable motor(VPDVM) is the future development trend of the hydraulic transmission of an unmanned ground vehicle(UGV).VPDVM is a dual-input single-output nonlinear system with coupling,which is difficult to control.High pressure automatic variables bang-bang(HABB) was proposed to achieve the desired motor speed.First,the VPDVM nonlinear mathematic model was introduced,then linearized by feedback linearization theory,and the zero-dynamic stability was proved.The HABB control algorithm was proposed for VPDVM,in which the variable motor was controlled by high pressure automatic variables(HA) and the variable pump was controlled by bang-bang.Finally,simulation of VPDVM controlled by HABB was developed.Simulation results demonstrate the HABB can implement the desired motor speed rapidly and has strong robustness against the variations of desired motor speed,load and pump speed.
文摘Chaos is a similar and random process which is very sensitive to initial value in deterministic system. It is a performance of nonlinear dynamical system with built-in randomness. Combined with the advantages and disadvantages of the present chaos encryption model, the paper proposes a chaotic stream cipher model based on chaos theory, which not only overcomes finite precision effect, but also improves the randomness of chaotic system and output sequence. The Sequence cycle theory generated by the algorithm can reach more than 10600 at least, which completely satisfies the actual application requirements of stream cipher system.
基金Supported by the National Natural Science Foundation of China under Grant No.10735030 the National Basic Research Programs of China (973 Programs) under Grant Nos.2007CB814800 and 2005CB422301the PCSIRT (IRT0734)
文摘Soliton theory plays an important role in nonlinear physics.The elastic interaction among solitons is oneof the most important properties for integrable systems.In this Letter, an elastic vortex interaction model is proposed.It is found that the momenta, vortex momenta and the energies of every one vortex and the interaction energies of everytwo vortices are conserved.
基金supported by the National Research Foundation of Korea Grant Funded by the Korea Government (Grant No. NRF-2015R1D1A3A01019789)
文摘We show the existence and multiplicity of solutions to degenerate p(x)-Laplace equations with Leray-Lions type operators using direct methods and critical point theories in Calculus of Variations and prove the uniqueness and nonnegativeness of solutions when the principal operator is monotone and the nonlinearity is nonincreasing. Our operator is of the most general form containing all previous ones and we also weaken assumptions on the operator and the nonlinearity to get the above results. Moreover, we do not impose the restricted condition on p(x) and the uniform monotonicity of the operator to show the existence of three distinct solutions.
