Simple and efficient stereo-selective synthesis of exo-5-norbornene-2-carboxylic acid (NBCA) is reported. Preliminary studies on base promoted isomerization of methyl 5-norbornene-2-carboxylate (MNBC) revealed that ra...Simple and efficient stereo-selective synthesis of exo-5-norbornene-2-carboxylic acid (NBCA) is reported. Preliminary studies on base promoted isomerization of methyl 5-norbornene-2-carboxylate (MNBC) revealed that rapid isomerization was accomplished with sodium tert-butoxide (tBuONa), and the exo-content at the equilibrium was ca. 60%. The hydrolyses of endo-rich MNBC (endo/exo = 80/20) under various conditions were carried out. The exo selectivity for resulting NBCA was improved when the hydrolysis was conducted with equimolar water at room temperature in the presence of the stronger base (tBuONa) (endo/exo: 18/82). Whereas the use of excess amount of water led to rapid and non-selective hydrolysis affording high endo content of the product. The plausible reaction mechanism involving rapid equilibrium of thermodynamic isomerization and kinetically preferred hydrolysis of exo ester is proposed.展开更多
In the test-field calibration,multi-azimuth stereo image pairs areproduced of the outdoor large control-field by the stereo-vision system under cali-bration.While in the analytical processing,the relationship between ...In the test-field calibration,multi-azimuth stereo image pairs areproduced of the outdoor large control-field by the stereo-vision system under cali-bration.While in the analytical processing,the relationship between image pairsis adopted as a constraint condition,which ensures the stability and quality of thecalibration results.This paper introduces the deduction process of the constraintconditions.展开更多
The quasi-classical trajectory （QCT） method is used to calculate the stereo-dynamics of the exchange reaction Ha＋LiHb→LiHa＋Hb and its isotopic variants based on an accurate potential energy surface reported by Pr...The quasi-classical trajectory （QCT） method is used to calculate the stereo-dynamics of the exchange reaction Ha＋LiHb→LiHa＋Hb and its isotopic variants based on an accurate potential energy surface reported by Prudente et al. [Prudente F V, Marques J M C and Maniero A M 2009 Chem. Phys. Lett. 474 18]. The reactive probability of the title reaction is computed. The vector correlations and four polarization-dependent generalized differential cross sections （PDDCSs） at different collision energies are presented. The influences of the collision energy and the reagent rotation on the product polarization are studied in the present work. The results indicate that the product rotational angular momentum j′ is not only aligned, but also oriented along the direction perpendicular to the scattering plane. The product polarization distributions of the title reaction and its isotopic variants exhibit distinct differences which may arise from different mass combinations.展开更多
A reaction of benzylic alcohols with alkenes has been developed in the presence of bis（trifluoromethane）sulfonimide for the synthesis of trisubstituted alkenes and indane derivatives with high stereoselectivity.In g...A reaction of benzylic alcohols with alkenes has been developed in the presence of bis（trifluoromethane）sulfonimide for the synthesis of trisubstituted alkenes and indane derivatives with high stereoselectivity.In general,benzylic alcohols react with 1,1-diaryl alkenes to afford trisubstituted alkenes,and the reaction with 1,2-disubstituted and trisubstituted alkenes affords indane derivatives through a [3 ＋ 2] annulation reaction.展开更多
Of the various kinds of research on the Virtual Reality and GIS, stereo-view is one of the key technologies . The following two aspects are covered in this paper. (1)Physiological fundamental of the natural binocular ...Of the various kinds of research on the Virtual Reality and GIS, stereo-view is one of the key technologies . The following two aspects are covered in this paper. (1)Physiological fundamental of the natural binocular stereo-vision, theory of 3D color TV and the stereo-view on the CRT screen are presented, especially the theory of widely adopted Time-Division System is introduced. (2) The preliminary practice for using the sterecrview technology on the screen to the terrain visual simulation is described, and the paper shows how to use 3DS to construct a movable real stereo terrain perspective by taking DTM data as the first hand information for the purpose of terrain visual simulation.展开更多
Single-camera stereo-digital image correlation(stereo-DIC) techniques have gained increasing attentions and demonstrated excellent prospects in the experimental mechanics community owing to their prominent advantages ...Single-camera stereo-digital image correlation(stereo-DIC) techniques have gained increasing attentions and demonstrated excellent prospects in the experimental mechanics community owing to their prominent advantages of cost-effectiveness,compactness, and the avoidance of the complicated camera synchronization. Using additional optical devices, e.g. a diffraction grating, a bi-prism or a set of planar mirrors, pseudo stereo images of a test sample surface can be recorded with a single camera.By correlating these stereo images using DIC, full-field three-dimensional(3 D) shape and deformation can be retrieved. This review comprehensively summarizes the historical development, methodologies, strengths and weaknesses of the diffraction grating-based, prism-based, four-mirror-adaptor-based single-camera stereo-DIC techniques, and the recently proposed novel full-frame single color camera-based stereo-DIC technique for full-field 3 D shape and deformation measurement. The optical arrangements, principles and calibration procedures of these single-camera stereo-DIC techniques are described in detail. Since high-speed deformation measurement is efficiently achieved by combining the single-camera stereo-DIC with one high-speed camera, single-camera stereo-DIC techniques show great potential in impact engineering, vibration and other dynamic tests.展开更多
文摘Simple and efficient stereo-selective synthesis of exo-5-norbornene-2-carboxylic acid (NBCA) is reported. Preliminary studies on base promoted isomerization of methyl 5-norbornene-2-carboxylate (MNBC) revealed that rapid isomerization was accomplished with sodium tert-butoxide (tBuONa), and the exo-content at the equilibrium was ca. 60%. The hydrolyses of endo-rich MNBC (endo/exo = 80/20) under various conditions were carried out. The exo selectivity for resulting NBCA was improved when the hydrolysis was conducted with equimolar water at room temperature in the presence of the stronger base (tBuONa) (endo/exo: 18/82). Whereas the use of excess amount of water led to rapid and non-selective hydrolysis affording high endo content of the product. The plausible reaction mechanism involving rapid equilibrium of thermodynamic isomerization and kinetically preferred hydrolysis of exo ester is proposed.
文摘In the test-field calibration,multi-azimuth stereo image pairs areproduced of the outdoor large control-field by the stereo-vision system under cali-bration.While in the analytical processing,the relationship between image pairsis adopted as a constraint condition,which ensures the stability and quality of thecalibration results.This paper introduces the deduction process of the constraintconditions.
基金Project supported by the National Natural Science Foundation of China(Grant No.11105022)the Fundamental Research Funds for the Central Universities(Grant Nos.2011QN142 and 2012QN066)
文摘The quasi-classical trajectory （QCT） method is used to calculate the stereo-dynamics of the exchange reaction Ha＋LiHb→LiHa＋Hb and its isotopic variants based on an accurate potential energy surface reported by Prudente et al. [Prudente F V, Marques J M C and Maniero A M 2009 Chem. Phys. Lett. 474 18]. The reactive probability of the title reaction is computed. The vector correlations and four polarization-dependent generalized differential cross sections （PDDCSs） at different collision energies are presented. The influences of the collision energy and the reagent rotation on the product polarization are studied in the present work. The results indicate that the product rotational angular momentum j′ is not only aligned, but also oriented along the direction perpendicular to the scattering plane. The product polarization distributions of the title reaction and its isotopic variants exhibit distinct differences which may arise from different mass combinations.
文摘A reaction of benzylic alcohols with alkenes has been developed in the presence of bis（trifluoromethane）sulfonimide for the synthesis of trisubstituted alkenes and indane derivatives with high stereoselectivity.In general,benzylic alcohols react with 1,1-diaryl alkenes to afford trisubstituted alkenes,and the reaction with 1,2-disubstituted and trisubstituted alkenes affords indane derivatives through a [3 ＋ 2] annulation reaction.
文摘Of the various kinds of research on the Virtual Reality and GIS, stereo-view is one of the key technologies . The following two aspects are covered in this paper. (1)Physiological fundamental of the natural binocular stereo-vision, theory of 3D color TV and the stereo-view on the CRT screen are presented, especially the theory of widely adopted Time-Division System is introduced. (2) The preliminary practice for using the sterecrview technology on the screen to the terrain visual simulation is described, and the paper shows how to use 3DS to construct a movable real stereo terrain perspective by taking DTM data as the first hand information for the purpose of terrain visual simulation.
基金supported by the National Natural Science Foundation of China(Grant Nos.11272032,11322220,11427802&11632010)the Aeronautical Science Foundation of China(Grant No.2016ZD51034)the Academic Excellence Foundation of BUAA for PhD Students
文摘Single-camera stereo-digital image correlation(stereo-DIC) techniques have gained increasing attentions and demonstrated excellent prospects in the experimental mechanics community owing to their prominent advantages of cost-effectiveness,compactness, and the avoidance of the complicated camera synchronization. Using additional optical devices, e.g. a diffraction grating, a bi-prism or a set of planar mirrors, pseudo stereo images of a test sample surface can be recorded with a single camera.By correlating these stereo images using DIC, full-field three-dimensional(3 D) shape and deformation can be retrieved. This review comprehensively summarizes the historical development, methodologies, strengths and weaknesses of the diffraction grating-based, prism-based, four-mirror-adaptor-based single-camera stereo-DIC techniques, and the recently proposed novel full-frame single color camera-based stereo-DIC technique for full-field 3 D shape and deformation measurement. The optical arrangements, principles and calibration procedures of these single-camera stereo-DIC techniques are described in detail. Since high-speed deformation measurement is efficiently achieved by combining the single-camera stereo-DIC with one high-speed camera, single-camera stereo-DIC techniques show great potential in impact engineering, vibration and other dynamic tests.
