In this study, a new mass model involving superheat, initial temperature, liquid height, evaporator diameter, and flashing time is established to describe the flash evaporation process of water film. Of 469 sets of fl...In this study, a new mass model involving superheat, initial temperature, liquid height, evaporator diameter, and flashing time is established to describe the flash evaporation process of water film. Of 469 sets of flash experimental data from three previous researches, 305 sets were applied to optimize parameters, and the other 164 sets were used to verify the practicability of the model. The results showed that the mean relative error between the literature data and the model values was less than 16.3%, and the model statistics proved that the model was well-posed. Then, the kinetic model was obtained using the time derivative of the new mass model. Computational fluid dynamics simulation of water film flash evaporation was studied based on a user-defined function program of the new evaporation kinetic model. The new kinetic model shows more consistency with the experimental phenomena in terms of evaporated mass and temperature compared with the evaporation–condensation model in Fluent software and Gopalakrishna's model. This new kinetic model can be extended to describe the flash process of water solution under other conditions.展开更多
Nonlinear interactions among incident wave, tank-sloshing and floating body coupling motion are investigated. The fully nonlinear sloshing and body-surface nonlinear free surface hydrodynamics is simulated using a Non...Nonlinear interactions among incident wave, tank-sloshing and floating body coupling motion are investigated. The fully nonlinear sloshing and body-surface nonlinear free surface hydrodynamics is simulated using a Non-Uniform Rational B-Spline （NURBS） higher-order panel method in time domain based on the potential theory. A robust and stable improved iterative procedure （Yan and Ma, 2007） for floating bodies is used for calculating the time derivative of velocity potential and floating body motion. An energy dissipation condition based on linear theory adopted by Huang （2011） is developed to consider flow viscosity effects of sloshing flow in nonlinear model. A two-dimensional tank model test was performed to identify its validity. The present nonlinear coupling sway motion results are subsequently compared with the corresponding Rognebakke and Faltinsen （2003）＇s experimental results, showing fair agreement. Thus, the numerical approach presented in this paper is expected to be very efficient and realistic in evaluating the coupling effects of nonlinear sloshing and body motion.展开更多
To solve the problems concerning water entry of a structure, the RANS equations and volume of fluid （VOF） method are used. Combining the user-defined function （UDF） procedure with dynamic grids, the water impact o...To solve the problems concerning water entry of a structure, the RANS equations and volume of fluid （VOF） method are used. Combining the user-defined function （UDF） procedure with dynamic grids, the water impact on a structure in free fall is simulated, and the velocity, displacement and the pressure distribution on the structure are investigated. The results of the numerical simulation were compared with the experimental data, and solidly consistent results have been achieved, which validates the numerical model. Therefore, this method can be used to study the water impact problems of a structure.展开更多
Due to the nonlinearity and uncertainty, the precise control of underwater vehicles in some intelligent operations hasn’t been solved very well yet. A novel method of control based on desired state programming was pr...Due to the nonlinearity and uncertainty, the precise control of underwater vehicles in some intelligent operations hasn’t been solved very well yet. A novel method of control based on desired state programming was presented, which used the technique of fuzzy neural network. The structure of fuzzy neural network was constructed according to the moving characters and the back propagation algorithm was deduced. Simulation experiments were conducted on general detection remotely operated vehicle. The results show that there is a great improvement in response and precision over traditional control, and good robustness to the model’s uncertainty and external disturbance, which has theoretical and practical value.展开更多
Exercise is a highly proven and beneficial health promotion modality, But it is very difficult to determine whether the person during exercise is safe. A unique and comprehensive approach is proposed to perform physic...Exercise is a highly proven and beneficial health promotion modality, But it is very difficult to determine whether the person during exercise is safe. A unique and comprehensive approach is proposed to perform physical exercise risk evaluation （PERE）, in which personalized factors are deterrrdned basing on grey correlation analysis, analytic hierarchy process （AHP） method is used to structure the large numbers of risk factors, and fuzzy comprehensive evaluation （FCE） is applied to fuzzify the factors and compute the exercise risk level. Finally, an actual calculation example is used to verify the feasibility of the method.展开更多
With the development of deepwater oil and gas exploration, Steel Catenary Risers(SCRs) become preferred risers for resource production, import and export. Vortex induced vibration(VIV) is the key problem encountered i...With the development of deepwater oil and gas exploration, Steel Catenary Risers(SCRs) become preferred risers for resource production, import and export. Vortex induced vibration(VIV) is the key problem encountered in the design of SCRs. In this study, a new model, the rigid swing model, is proposed based on the consideration of large curvature of SCRs. The sag bend of SCRs is assumed as a rigid swing system around the axis from the hanging point to the touch down point(TDP) in the model. The torque, produced by the lift force and the swing vector, provides the driving torque for the swing system, and the weight of SCRs provides the restoring torque. The simulated response of rigid swing is coupled with bending vibration, and then the coupling VIV model of SCRs is studied in consideration of bending vibration and rigid motion. The calculated results indicate that the rigid swing has a magnitude equal to that of bending vibration, and the rigid motion affects the dynamic response of SCRs and can not be neglected in the VIV analysis.展开更多
Along with the development of motion capture technique, more and more 3D motion databases become available. In this paper, a novel approach is presented for motion recognition and retrieval based on ensemble HMM (hidd...Along with the development of motion capture technique, more and more 3D motion databases become available. In this paper, a novel approach is presented for motion recognition and retrieval based on ensemble HMM (hidden Markov model) learning. Due to the high dimensionality of motion’s features, Isomap nonlinear dimension reduction is used for training data of ensemble HMM learning. For handling new motion data, Isomap is generalized based on the estimation of underlying eigen- functions. Then each action class is learned with one HMM. Since ensemble learning can effectively enhance supervised learning, ensembles of weak HMM learners are built. Experiment results showed that the approaches are effective for motion data recog- nition and retrieval.展开更多
An air-gun source is the most commonly used excitation method in off shore seismic exploration.The excitation characteristics of an air-gun source aff ect seismic data quality.Far-field wavelet simulation is an import...An air-gun source is the most commonly used excitation method in off shore seismic exploration.The excitation characteristics of an air-gun source aff ect seismic data quality.Far-field wavelet simulation is an important approach to study these characteristics.Compared to the measured wavelet,far-field wavelet simulation based on a traditional bubble-motion equation and ideal gas wavelet model has some disadvantages,such as a greater amplitude and smaller pulse attenuation velocity.Here,we start from the linear acoustic wave equation in the spherical coordinate system to deduce an improved,simpler bubble-motion equation and develop a Van der Waals gas wavelet model based on this equation.Unlike the existing methods,our method considers the high-pressure environment during actual excitation,heat exchange between the bubble and outside water,and change in the air fl ow at the muzzle.The results show that the far-fi eld wavelet simulated using this model is closer to the measured wavelet than that of the ideal gas wavelet model.At the same time,our method has a more succinct equation and a higher calculation effi ciency.展开更多
The effect of varying pore structures on the kinetics of S02-CaO reactions is not fully understood in the previous studies. Combining fractal pore model, gas molecular movement model and two-stage reaction model, a ne...The effect of varying pore structures on the kinetics of S02-CaO reactions is not fully understood in the previous studies. Combining fractal pore model, gas molecular movement model and two-stage reaction model, a new desulfurization model is established in this paper. Fractal pore model is used to simulate CaO particle and gas molecular movement model is used to simulate gas diffusion in pores. Fractal dimension is used to characterize complexity of pore structure instead of tortuosity factor. It is found that the reaction is significantly affected by pore structures. A modulus φ is introduced to characterize the relationship between varying pore structures and apparent reaction parameters. And this relationship is verified by thermo-gravimetric analysis （TGA） data. Comparing to the previous models, the effect of varying pore structure on the kinetics of the reaction is described more accurately by the desulfurization model.展开更多
A new method of elastic articulated objects (human bodies) modeling was presented based on a new conic curve. The model includes 3D object deformable curves which can represent the deformation of human occluding conto...A new method of elastic articulated objects (human bodies) modeling was presented based on a new conic curve. The model includes 3D object deformable curves which can represent the deformation of human occluding contours. The deformation of human occluding contour can be represented by adjusting only four deformation parameters for each limb. Then, the 3D deformation parameters are determined by corresponding 2D contours from a sequence of stereo images. The algorithm presented in this paper includes deformable conic curve parameters determination and the plane, 3D conic curve lying on, parameter determination.展开更多
基金supported by the Scientific Research Special Fund of Marine Public Welfare Industry(No.20140508)National Natural Science Foundation of China(No.51478308)Natural Science Foundation of Tianjin(No.14JCYBJC23300)
文摘In this study, a new mass model involving superheat, initial temperature, liquid height, evaporator diameter, and flashing time is established to describe the flash evaporation process of water film. Of 469 sets of flash experimental data from three previous researches, 305 sets were applied to optimize parameters, and the other 164 sets were used to verify the practicability of the model. The results showed that the mean relative error between the literature data and the model values was less than 16.3%, and the model statistics proved that the model was well-posed. Then, the kinetic model was obtained using the time derivative of the new mass model. Computational fluid dynamics simulation of water film flash evaporation was studied based on a user-defined function program of the new evaporation kinetic model. The new kinetic model shows more consistency with the experimental phenomena in terms of evaporated mass and temperature compared with the evaporation–condensation model in Fluent software and Gopalakrishna's model. This new kinetic model can be extended to describe the flash process of water solution under other conditions.
基金Foundation item： Supported by the National Natural Science Foundation of China （Grant No. 51079032） and the ＂111 project＂ （Grant No. B07019）.
文摘Nonlinear interactions among incident wave, tank-sloshing and floating body coupling motion are investigated. The fully nonlinear sloshing and body-surface nonlinear free surface hydrodynamics is simulated using a Non-Uniform Rational B-Spline （NURBS） higher-order panel method in time domain based on the potential theory. A robust and stable improved iterative procedure （Yan and Ma, 2007） for floating bodies is used for calculating the time derivative of velocity potential and floating body motion. An energy dissipation condition based on linear theory adopted by Huang （2011） is developed to consider flow viscosity effects of sloshing flow in nonlinear model. A two-dimensional tank model test was performed to identify its validity. The present nonlinear coupling sway motion results are subsequently compared with the corresponding Rognebakke and Faltinsen （2003）＇s experimental results, showing fair agreement. Thus, the numerical approach presented in this paper is expected to be very efficient and realistic in evaluating the coupling effects of nonlinear sloshing and body motion.
基金Foundation item： Supported by the of China （11302056）, China National Natural Science Foundation Postdoctoral Science Foundation （2013M540272）, Heilongjiang Postdoctoral Fund （LBH-ZI3051）, the Fundamental Research Funds for the Central Universities （HEUCF140116） and Research Fund of State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University （1309）.
文摘To solve the problems concerning water entry of a structure, the RANS equations and volume of fluid （VOF） method are used. Combining the user-defined function （UDF） procedure with dynamic grids, the water impact on a structure in free fall is simulated, and the velocity, displacement and the pressure distribution on the structure are investigated. The results of the numerical simulation were compared with the experimental data, and solidly consistent results have been achieved, which validates the numerical model. Therefore, this method can be used to study the water impact problems of a structure.
基金Supported by the National High Technology and Development Program Foundation of China under Grant No. 2002AA420090.
文摘Due to the nonlinearity and uncertainty, the precise control of underwater vehicles in some intelligent operations hasn’t been solved very well yet. A novel method of control based on desired state programming was presented, which used the technique of fuzzy neural network. The structure of fuzzy neural network was constructed according to the moving characters and the back propagation algorithm was deduced. Simulation experiments were conducted on general detection remotely operated vehicle. The results show that there is a great improvement in response and precision over traditional control, and good robustness to the model’s uncertainty and external disturbance, which has theoretical and practical value.
基金The Cultivation Fund of the Key Scientific and Technical Innovation Project from Ministry of Education of China(No706024)International Science Cooperation Foundation of Shanghai ( No061307041)Specialized Research Fund for the Doctoral Program of Higher Education from Ministry of Education of China (No20060255006)
文摘Exercise is a highly proven and beneficial health promotion modality, But it is very difficult to determine whether the person during exercise is safe. A unique and comprehensive approach is proposed to perform physical exercise risk evaluation （PERE）, in which personalized factors are deterrrdned basing on grey correlation analysis, analytic hierarchy process （AHP） method is used to structure the large numbers of risk factors, and fuzzy comprehensive evaluation （FCE） is applied to fuzzify the factors and compute the exercise risk level. Finally, an actual calculation example is used to verify the feasibility of the method.
基金funded by the National Natural Science Foundation of China(51079136,51179179,51239008)
文摘With the development of deepwater oil and gas exploration, Steel Catenary Risers(SCRs) become preferred risers for resource production, import and export. Vortex induced vibration(VIV) is the key problem encountered in the design of SCRs. In this study, a new model, the rigid swing model, is proposed based on the consideration of large curvature of SCRs. The sag bend of SCRs is assumed as a rigid swing system around the axis from the hanging point to the touch down point(TDP) in the model. The torque, produced by the lift force and the swing vector, provides the driving torque for the swing system, and the weight of SCRs provides the restoring torque. The simulated response of rigid swing is coupled with bending vibration, and then the coupling VIV model of SCRs is studied in consideration of bending vibration and rigid motion. The calculated results indicate that the rigid swing has a magnitude equal to that of bending vibration, and the rigid motion affects the dynamic response of SCRs and can not be neglected in the VIV analysis.
基金Project supported by the National Natural Science Foundation of China (Nos. 60533090 and 60525108), the National Basic Research Program (973) of China (No. 2002CB312101), and the Science and Technology Project of Zhejiang Province (Nos. 2005C13032 and 2005C11001-05), China
文摘Along with the development of motion capture technique, more and more 3D motion databases become available. In this paper, a novel approach is presented for motion recognition and retrieval based on ensemble HMM (hidden Markov model) learning. Due to the high dimensionality of motion’s features, Isomap nonlinear dimension reduction is used for training data of ensemble HMM learning. For handling new motion data, Isomap is generalized based on the estimation of underlying eigen- functions. Then each action class is learned with one HMM. Since ensemble learning can effectively enhance supervised learning, ensembles of weak HMM learners are built. Experiment results showed that the approaches are effective for motion data recog- nition and retrieval.
基金supported by National Natural Science Foundation of China (No. 41674118)
文摘An air-gun source is the most commonly used excitation method in off shore seismic exploration.The excitation characteristics of an air-gun source aff ect seismic data quality.Far-field wavelet simulation is an important approach to study these characteristics.Compared to the measured wavelet,far-field wavelet simulation based on a traditional bubble-motion equation and ideal gas wavelet model has some disadvantages,such as a greater amplitude and smaller pulse attenuation velocity.Here,we start from the linear acoustic wave equation in the spherical coordinate system to deduce an improved,simpler bubble-motion equation and develop a Van der Waals gas wavelet model based on this equation.Unlike the existing methods,our method considers the high-pressure environment during actual excitation,heat exchange between the bubble and outside water,and change in the air fl ow at the muzzle.The results show that the far-fi eld wavelet simulated using this model is closer to the measured wavelet than that of the ideal gas wavelet model.At the same time,our method has a more succinct equation and a higher calculation effi ciency.
基金Supported by the National Natural Science Foundation of China(51176096)
文摘The effect of varying pore structures on the kinetics of S02-CaO reactions is not fully understood in the previous studies. Combining fractal pore model, gas molecular movement model and two-stage reaction model, a new desulfurization model is established in this paper. Fractal pore model is used to simulate CaO particle and gas molecular movement model is used to simulate gas diffusion in pores. Fractal dimension is used to characterize complexity of pore structure instead of tortuosity factor. It is found that the reaction is significantly affected by pore structures. A modulus φ is introduced to characterize the relationship between varying pore structures and apparent reaction parameters. And this relationship is verified by thermo-gravimetric analysis （TGA） data. Comparing to the previous models, the effect of varying pore structure on the kinetics of the reaction is described more accurately by the desulfurization model.
基金the Postdoctoral Science Foundation of China(Grant No.20070421018)
文摘A new method of elastic articulated objects (human bodies) modeling was presented based on a new conic curve. The model includes 3D object deformable curves which can represent the deformation of human occluding contours. The deformation of human occluding contour can be represented by adjusting only four deformation parameters for each limb. Then, the 3D deformation parameters are determined by corresponding 2D contours from a sequence of stereo images. The algorithm presented in this paper includes deformable conic curve parameters determination and the plane, 3D conic curve lying on, parameter determination.
