摘要 :
Analytical methods of nonlinear dynamics and numerical simulations for the coupling equations of Navier-Stokes and flight mechanics are used to study the dynamic behaviour of pitching motions of reentry capsules with the variation...
展开
Analytical methods of nonlinear dynamics and numerical simulations for the coupling equations of Navier-Stokes and flight mechanics are used to study the dynamic behaviour of pitching motions of reentry capsules with the variation of Mach number, and rocking motions of swept wings with the variation of angle of attack. Conditions under which the dynamic instability, Hopf bifurcation and saddle-node bifurcation occur are obtained. The node-saddle-node topological structure in the phase portrait, i.e. the state of bi-attractors (attracting basins) is described. The evolving process of dynamic behaviour and flow fields are given. The theories are compared with some numerical simulations conducted by the authors. Besides, some verifiable experimental results are cited. The agreement between them is very well.
收起
摘要 :
A novel route for methane conversion to higher hydrocarbons over Mo/HZSM-5 catalysts without adding O_2 is reported. The product is mainly benzene and is formed via oligomerization of ethylene. This reaction proces probably occurs...
展开
A novel route for methane conversion to higher hydrocarbons over Mo/HZSM-5 catalysts without adding O_2 is reported. The product is mainly benzene and is formed via oligomerization of ethylene. This reaction proces probably occurs on two remotely separated active sites. Ethylene is initially formed as the primary product on the externally loaded Mo active sites while aromatic products are formed on the Bronsted acid sites in the channel systems. In order to relate these two processes, an intermediate diffusion process involving ethylene from the external surface into the channel systems is proposed.
收起
摘要 :
Both Ha-CdS and HB-CdS (Hys-CdS, Hys represents HA, Hb) complex systems were established according to the dynamics of heterogeneous electron-transfer process μ=E_s/s-E_cb展开
Both Ha-CdS and HB-CdS (Hys-CdS, Hys represents HA, Hb) complex systems were established according to the dynamics of heterogeneous electron-transfer process μ=E_s/s-E_cb收起
摘要 :
In this paper some new advances in the study of fluid inclusions of the Yinshan de- posit in Jiangxi Province, China, are presented. The fluid inclusions of the deposit an be di- vided into four types: 1)gas-rich inclusions; 2)liq...
展开
In this paper some new advances in the study of fluid inclusions of the Yinshan de- posit in Jiangxi Province, China, are presented. The fluid inclusions of the deposit an be di- vided into four types: 1)gas-rich inclusions; 2)liquid-rich inclusions; 3)salt-saturated H_2O inclusion; and 4)single-phase or multiphase CO_2-rich inclusions. Homogenization tempera- tures of the fluid inclusions range for 100 to 520 deg. C, mainly in the range 120-400 deg. C. The daughter crystal-bearing multiphase inclusions present in quartz porphyries(including Nos. 13 and 4 dikes)have been observed.
收起
摘要 :
Purpose - The purpose of this paper is to provide a flexible registration method for markerless augmented reality (AR) systems.
Design/methodology/approach - The proposed method distinguishes itself as follows: firstly, the metho...
展开
Purpose - The purpose of this paper is to provide a flexible registration method for markerless augmented reality (AR) systems.
Design/methodology/approach - The proposed method distinguishes itself as follows: firstly, the method is simple and efficient, as no man-made
markers are needed for both indoor and outdoor AR applications. Secondly, an adaptation method is presented to tune the particle filter dynamically.
The result is a system which can achieve tolerance to fast motion and drift during tracking process. Thirdly, the authors use the reduced scale invariant
feature transform (SIFT) and scale prediction techniques to match natural features. This method deals easily with the camera pose estimation problem
in the case of large illumination and visual angle changes.
Findings - Some experiments are provided to validate the performance of the proposed method.
Originality/value - The paper proposes a novel camera pose estimation method based on adaptive particle filter and natural features matching
techniques.
收起
摘要 :
The treatment of tetrakis (4-pyridyl) porphyrin H_2TpyP with a hydrated rare earth (III) acetylacetonate RE (acac)_3 ·nH_2O (RE=Y, Eu, Gd) in 1,2,4-trichlorobenzene (TCB) pro- duced a monomeric porphyrinato rare earth compound RE...
展开
The treatment of tetrakis (4-pyridyl) porphyrin H_2TpyP with a hydrated rare earth (III) acetylacetonate RE (acac)_3 ·nH_2O (RE=Y, Eu, Gd) in 1,2,4-trichlorobenzene (TCB) pro- duced a monomeric porphyrinato rare earth compound RE (TpyP) acac, which further reacted with dicyanobenzen in amyl alcohol in the presence of 1, 8-diazabicyclo [5.4.0] undec-7-ene (DBU), giving HRE(TpyP) (Pc) in a good yield. Upon exposure to air, part of the protonated mixed double-deckers in CHCl_3 solutions converted slowly to the corresponding neutral complexes RE (TpyP) (Pc).
收起
摘要 :
CONCLUSION: The isolated cDNA clone encodes an isoenzyme of mitochondrial VLCAD in bovine heart. AIM: To clone the cDNA encoding an isoenzyme of mitochondrial very-long-chain acyl-CoA dehydro- genase (VLCAD) from bovine heart λgt...
展开
CONCLUSION: The isolated cDNA clone encodes an isoenzyme of mitochondrial VLCAD in bovine heart. AIM: To clone the cDNA encoding an isoenzyme of mitochondrial very-long-chain acyl-CoA dehydro- genase (VLCAD) from bovine heart λgt11 and λgt10 cDNA libraries. METHODS: The clone was isolated with immunoscreening technique and validated by (1) the microsequences of the N- terminus and three internal proteolytic fragments from the purified enzyme; (2) identification of the acyl-CoA dehydrogenase (AD) signature sequence; and (3) high homology of the deduced peptide sequences, as expected, with those of rat liver mitochondrial VLCAD. RESULTS: The cDNA (2203 bp) corresponds to a ～2.4-kb mRNA band from the same tissue source revealed by a Northern blotting.
收起
摘要 :
A new approach for the solution of truss shape and topology optimization problems under local and global stability constraints is proposed. By employing the cross sectional areas of each bar and some shape parameters as topology d...
展开
A new approach for the solution of truss shape and topology optimization problems under local and global stability constraints is proposed. By employing the cross sectional areas of each bar and some shape parameters as topology design variables, the difficulty arising from the jumping of buckling length phenomenon can be easily overcome without the necessity of introducing the overlapping bars into the initial ground structure. Therefore computational efforts can be saved for the solution of this kind of problem. By modifying the elements of the stiffness matrix using Sigmoid function, the continuity of the objective and constraint functions with respect to shape design parameters can be restored to some extent. Some numerical examples demonstrate the effectiveness of the proposed method.
收起
摘要 :
A hybrid opto-electronic correlator for detecting defects in optical fibers is processed. After the light from a He-Ne laser being expanded and filtered it is not collimated but directly passes a Fourier transform lens and illumin...
展开
A hybrid opto-electronic correlator for detecting defects in optical fibers is processed. After the light from a He-Ne laser being expanded and filtered it is not collimated but directly passes a Fourier transform lens and illuminates a reference fiber and a test fiber at the same input plane. The Fourier transform spectrum of the two fibers is therefore obtained at the rear focal plane of the lens, where it is sampled via a CCD array connected with a computer through a frame grabber. The computer performs filter, inverse Fourier transform and setting threshold operation on classification. The system is an equivalent of joint transform correlator with a Fourier lens of long focal length. The experiment results for optical fibers having in coordinate defects are presented. The results indicate that the system can be used for fiber defect detection, and has the advantages of high identification, compact configuration, easy adjustment and flexible manipulation.
收起
摘要 :
Based on the FEA software ANSYS, a model was developed to simulate the thermal stress distribution of inert anode. In order to reduce its thermal stress, the effect of some parameters on thermal stress distribution was investigate...
展开
Based on the FEA software ANSYS, a model was developed to simulate the thermal stress distribution of inert anode. In order to reduce its thermal stress, the effect of some parameters on thermal stress distribution was investigated, including the temperature of electrolyte, the current, the anode cathode distance, the anode immersion depth, the surrounding temperature and the convection coefficient between anode and circumstance. The results show that there exists a large axial tensile stress near the tangent interface between the anode and bath, which is the major cause of anode breaking. Increasing the temperature of electrolyte or the anode immersion depth will deteriorate the stress distribution of inert anode. When the bath temperature increases from 750 to 970 ℃, the maximal value and absolute minimal value of the 1st principal stress increase by 29.7% and 29.6%, respectively. When the anode immersion depth is changed from 1 to 10 cm, the maximal value and absolute minimal value of the 1st principal stress increase by 52.1% and 65.0%, respectively. The effects of other parameters on stress distribution are not significant.
收起
