In order to predict accurately the characteristics of supersonic flow in new type externally pressurized spherical air bearings under large bearing clearance and high air supply pressure, which could decrease their lo...In order to predict accurately the characteristics of supersonic flow in new type externally pressurized spherical air bearings under large bearing clearance and high air supply pressure, which could decrease their load carrying capacity and stability, a CFD-based analysis was introduced to solve the three-dimensional turbulent complete compressible air flow governing equations. The realizable κ-ε model was used as a turbulent closure illustrate that the interaction exists between shock waves The supersonic flow field near air inlets was analyzed. The flow structures and boundary layer, and the flow separation is formed at the lower comer and the lower wall around the point of a maximum velocity. The numerical results show that the conversion from supersonic flow to subsonic flow in spherical air bearing occurs through a shock region （pseudo-shock）, and the viscous boundary layer results in the flow separation and reverse flow near the shock. The calculation results basically agree with the corresponding experimental data.展开更多
Information analysis of high dimensional data was carried out through similarity measure application. High dimensional data were considered as the a typical structure. Additionally, overlapped and non-overlapped data ...Information analysis of high dimensional data was carried out through similarity measure application. High dimensional data were considered as the a typical structure. Additionally, overlapped and non-overlapped data were introduced, and similarity measure analysis was also illustrated and compared with conventional similarity measure. As a result, overlapped data comparison was possible to present similarity with conventional similarity measure. Non-overlapped data similarity analysis provided the clue to solve the similarity of high dimensional data. Considering high dimensional data analysis was designed with consideration of neighborhoods information. Conservative and strict solutions were proposed. Proposed similarity measure was applied to express financial fraud among multi dimensional datasets. In illustrative example, financial fraud similarity with respect to age, gender, qualification and job was presented. And with the proposed similarity measure, high dimensional personal data were calculated to evaluate how similar to the financial fraud. Calculation results show that the actual fraud has rather high similarity measure compared to the average, from minimal 0.0609 to maximal 0.1667.展开更多
This study aims to examine and analyze the effect of corrosion wastage on the ship hull of a double hull very large crude oil carrier. To calculate the ultimate bending moment capacity, along with the neutral axis pos...This study aims to examine and analyze the effect of corrosion wastage on the ship hull of a double hull very large crude oil carrier. To calculate the ultimate bending moment capacity, along with the neutral axis position at the limit state, section modulus, and moment of inertia, the incremental-iterative method is employed. This paper also considered the residual strength checking criteria of ship hull and the ultimate stress behaviors of the representative structural elements. Then, Paik's probabilistic corrosion, which employs two levels of corrosion rate and three different assumptions of coating life time, is applied to assess the corrosion effects. The calculation results obtained through relevant analyses are also presented.展开更多
Regarding the growth of global energy consumption and the paucity of light crude oil, extracting and using heavy and extra heavy crude oil has received much more attention, but the application of this kind of oil is c...Regarding the growth of global energy consumption and the paucity of light crude oil, extracting and using heavy and extra heavy crude oil has received much more attention, but the application of this kind of oil is complicated due to its very high molecular weight. High viscosity and low flowability complicate the transportation of heavy and extra heavy crude oil. Accordingly, it is essential to reduce the viscosity of heavy and extra heavy crude oil through in-situ operations or immediate actions after extraction to reduce costs. Numerical simulations are influential methods, because they reduce calculation time and costs. In this study, the cracking of extra heavy crude oil using computational fluid dynamics is simulated, and a unique kinetic model is proposed based on experimental procedures to predict the behavior of extra heavy crude oil cracking reaction. Moreover, the hydrodynamics and heat transfer of the system and influence of nanocatalysts and temperature on the upgrading of crude oil are studied. The geometry of a reactor is produced using commercial software, and some experiments are performed to examine the validity and accuracy of the numerical results. The findings reveal that there is a good agreement between the numerical and experimental results. Furthermore, to investigate the main factors affecting the process, sensitivity analysis is adopted. Results show that type of catalyst and concentration of catalyst are the parameters that influence the viscosity reduction of extra heavy crude oil the most. The findings further revealed that when using a 25 nm SiO_2 nanocatalyst, a maximum viscosity reduction of 98.67% is observed at 623 K. Also, a catalyst concentration of 2.28 wt% is best for upgrading extra heavy crude oil. The results obtained through sensitivity analysis, simulation model, and experiments represent effectual information for the design and development of high performance upgrading processes for energy applications.展开更多
The ethoxycarbonyl isothiocyanate has been investigated by using supersonic jet Fourier transform microwave spectroscopy.Two sets of rotational spectra belonging to conformers TCC(with the backbone of C-C-O-C,C-O-C=O,...The ethoxycarbonyl isothiocyanate has been investigated by using supersonic jet Fourier transform microwave spectroscopy.Two sets of rotational spectra belonging to conformers TCC(with the backbone of C-C-O-C,C-O-C=O,and O-C(=O)-NCS being trans,cis,and cis arranged,respectively)and GCC(gauche,cis,and cis arrangement of the C-C-O-C,C-O-C=O,and O-C(=O)-NCS)have been measured and assigned.The measurements of13C,15N and34S mono-substituted species of the two conformers have also been performed.The comprehensive rotational spectroscopic investigations provide accurate values of rotational constants and14N quadrupole coupling constants,which lead to structural determinations of the two conformers of ethoxycarbonyl isothiocyanate.For conformer TCC,the values of Pcckeep constant upon isotopic substitution,indicating that the heavy atoms of TCC are effectively located in the ab plane.展开更多
Due to the correlation and diversity of robotic kinematic dexterity indexes, the principal component analysis （PCA） and kernel principal component analysis （KPCA） based on linear dimension reduction and nonlinear ...Due to the correlation and diversity of robotic kinematic dexterity indexes, the principal component analysis （PCA） and kernel principal component analysis （KPCA） based on linear dimension reduction and nonlinear dimension reduction principle could be respectively introduced into comprehensive kinematic dexterity performance evaluation of space 3R robot of different tasks. By comparing different dimension reduction effects, the KPCA method could deal more effectively with the nonlinear relationship among different single kinematic dexterity indexes, and its calculation result is more reasonable for containing more comprehensive information. KPCA＇ s calculation provides scientific basis for optimum order of robotic tasks, and furthermore a new optimization method for robotic task selection is proposed based on various performance indexes.展开更多
Fracture processes in ship-building structures are in many cases of a 3-D character. A finite element （FE） model of an all fracture mode （AFM） specimen was built for the study of 3-D mixed mode crack fracture beha...Fracture processes in ship-building structures are in many cases of a 3-D character. A finite element （FE） model of an all fracture mode （AFM） specimen was built for the study of 3-D mixed mode crack fracture behavior including modes Ⅰ,Ⅱ, and Ⅲ. The stress intensity factors （SIFs） were calculated by the modified virtual crack closure integral （MVCCI） method, and the crack initiation angle assessment was based on a recently developed 3-D fracture criterion--the Richard criterion. It was shown that the FE model of the AFM-specimen is applicable for investigations under general mixed mode loading conditions, and the computational results of crack initiation angles are in agreement with some available experimental findings. Thus, the applicability of the FE model of the AFM-specimen for mixed mode loading conditions and the validity of the Richard criterion can be demonstrated.展开更多
文摘TN242 2001010210钛宝石自锁模激光器谐振腔特性分析=Analysis ofthe resonant cavity of self-mode-locked Ti:sappire laser[刊,中]/王春林,陈檬,李港,刘晔(北京工业大学激光技术实验室.北京(100022))∥北京工业大学学报.-2000,22(2).-98-101给出一种简单有效的计算钛宝石自锁模激光器中腔内各点光斑的归一变化率的计算方法,计算了腔内各点的光斑归一变化率,利用计算结果分析了其变化特性,在此基础上获得了晶体在腔内最佳位置的计算方法。图6参5(苏锡安)TN243 2001010211强干扰激光电源同步信号取出与建模仿真设计=Exporting of synchronized signal from
基金Project(2002AA742049) supported by the National High Technology Research and Development Program of China
文摘In order to predict accurately the characteristics of supersonic flow in new type externally pressurized spherical air bearings under large bearing clearance and high air supply pressure, which could decrease their load carrying capacity and stability, a CFD-based analysis was introduced to solve the three-dimensional turbulent complete compressible air flow governing equations. The realizable κ-ε model was used as a turbulent closure illustrate that the interaction exists between shock waves The supersonic flow field near air inlets was analyzed. The flow structures and boundary layer, and the flow separation is formed at the lower comer and the lower wall around the point of a maximum velocity. The numerical results show that the conversion from supersonic flow to subsonic flow in spherical air bearing occurs through a shock region （pseudo-shock）, and the viscous boundary layer results in the flow separation and reverse flow near the shock. The calculation results basically agree with the corresponding experimental data.
基金Project(RDF 11-02-03)supported by the Research Development Fund of XJTLU,China
文摘Information analysis of high dimensional data was carried out through similarity measure application. High dimensional data were considered as the a typical structure. Additionally, overlapped and non-overlapped data were introduced, and similarity measure analysis was also illustrated and compared with conventional similarity measure. As a result, overlapped data comparison was possible to present similarity with conventional similarity measure. Non-overlapped data similarity analysis provided the clue to solve the similarity of high dimensional data. Considering high dimensional data analysis was designed with consideration of neighborhoods information. Conservative and strict solutions were proposed. Proposed similarity measure was applied to express financial fraud among multi dimensional datasets. In illustrative example, financial fraud similarity with respect to age, gender, qualification and job was presented. And with the proposed similarity measure, high dimensional personal data were calculated to evaluate how similar to the financial fraud. Calculation results show that the actual fraud has rather high similarity measure compared to the average, from minimal 0.0609 to maximal 0.1667.
文摘This study aims to examine and analyze the effect of corrosion wastage on the ship hull of a double hull very large crude oil carrier. To calculate the ultimate bending moment capacity, along with the neutral axis position at the limit state, section modulus, and moment of inertia, the incremental-iterative method is employed. This paper also considered the residual strength checking criteria of ship hull and the ultimate stress behaviors of the representative structural elements. Then, Paik's probabilistic corrosion, which employs two levels of corrosion rate and three different assumptions of coating life time, is applied to assess the corrosion effects. The calculation results obtained through relevant analyses are also presented.
基金Supported by the Iranian National Science Foundation(INSF)under grant number91042428
文摘Regarding the growth of global energy consumption and the paucity of light crude oil, extracting and using heavy and extra heavy crude oil has received much more attention, but the application of this kind of oil is complicated due to its very high molecular weight. High viscosity and low flowability complicate the transportation of heavy and extra heavy crude oil. Accordingly, it is essential to reduce the viscosity of heavy and extra heavy crude oil through in-situ operations or immediate actions after extraction to reduce costs. Numerical simulations are influential methods, because they reduce calculation time and costs. In this study, the cracking of extra heavy crude oil using computational fluid dynamics is simulated, and a unique kinetic model is proposed based on experimental procedures to predict the behavior of extra heavy crude oil cracking reaction. Moreover, the hydrodynamics and heat transfer of the system and influence of nanocatalysts and temperature on the upgrading of crude oil are studied. The geometry of a reactor is produced using commercial software, and some experiments are performed to examine the validity and accuracy of the numerical results. The findings reveal that there is a good agreement between the numerical and experimental results. Furthermore, to investigate the main factors affecting the process, sensitivity analysis is adopted. Results show that type of catalyst and concentration of catalyst are the parameters that influence the viscosity reduction of extra heavy crude oil the most. The findings further revealed that when using a 25 nm SiO_2 nanocatalyst, a maximum viscosity reduction of 98.67% is observed at 623 K. Also, a catalyst concentration of 2.28 wt% is best for upgrading extra heavy crude oil. The results obtained through sensitivity analysis, simulation model, and experiments represent effectual information for the design and development of high performance upgrading processes for energy applications.
基金The support from the National Natural Science Foundation of China(No.22273009)Chongqing University。
文摘The ethoxycarbonyl isothiocyanate has been investigated by using supersonic jet Fourier transform microwave spectroscopy.Two sets of rotational spectra belonging to conformers TCC(with the backbone of C-C-O-C,C-O-C=O,and O-C(=O)-NCS being trans,cis,and cis arranged,respectively)and GCC(gauche,cis,and cis arrangement of the C-C-O-C,C-O-C=O,and O-C(=O)-NCS)have been measured and assigned.The measurements of13C,15N and34S mono-substituted species of the two conformers have also been performed.The comprehensive rotational spectroscopic investigations provide accurate values of rotational constants and14N quadrupole coupling constants,which lead to structural determinations of the two conformers of ethoxycarbonyl isothiocyanate.For conformer TCC,the values of Pcckeep constant upon isotopic substitution,indicating that the heavy atoms of TCC are effectively located in the ab plane.
基金Supported by the National Natural Science Foundation of China(No.51075005)the Beijing City Science and Technology Project(No.Z131100005313009)
文摘Due to the correlation and diversity of robotic kinematic dexterity indexes, the principal component analysis （PCA） and kernel principal component analysis （KPCA） based on linear dimension reduction and nonlinear dimension reduction principle could be respectively introduced into comprehensive kinematic dexterity performance evaluation of space 3R robot of different tasks. By comparing different dimension reduction effects, the KPCA method could deal more effectively with the nonlinear relationship among different single kinematic dexterity indexes, and its calculation result is more reasonable for containing more comprehensive information. KPCA＇ s calculation provides scientific basis for optimum order of robotic tasks, and furthermore a new optimization method for robotic task selection is proposed based on various performance indexes.
文摘Fracture processes in ship-building structures are in many cases of a 3-D character. A finite element （FE） model of an all fracture mode （AFM） specimen was built for the study of 3-D mixed mode crack fracture behavior including modes Ⅰ,Ⅱ, and Ⅲ. The stress intensity factors （SIFs） were calculated by the modified virtual crack closure integral （MVCCI） method, and the crack initiation angle assessment was based on a recently developed 3-D fracture criterion--the Richard criterion. It was shown that the FE model of the AFM-specimen is applicable for investigations under general mixed mode loading conditions, and the computational results of crack initiation angles are in agreement with some available experimental findings. Thus, the applicability of the FE model of the AFM-specimen for mixed mode loading conditions and the validity of the Richard criterion can be demonstrated.
