In order to obtain a new-type short cylindrical cup-shaped flexspline that can be applied to space mechanisms,the APDL language of ANSYS software was employed to develop a parameterized equivalent contact model betwee...In order to obtain a new-type short cylindrical cup-shaped flexspline that can be applied to space mechanisms,the APDL language of ANSYS software was employed to develop a parameterized equivalent contact model between a flexspline and a wave generator. The validity of the parameterized equivalent contact model was verified by comparing the results of the analytic value of the contact model and the value calculated by the theoretical formula. The curvilinear trend of stress was obtained by changing the structural parameter of the flexspline. Based on the curvilinear trend of stress,multi-objective optimizations of key structural parameters were achieved. Flexspline,wave generator,and circular spline of a new 32-type short cylindrical cup-shaped harmonic reducer were designed and manufactured. A performance test bench to carry out tests on the harmonic reducer was designed. Contrast experiments were implemented to determine the efficiency of the new 32-type short cylindrical cup-shaped harmonic reducer and the conventional 32-type harmonic reducer under different conditions. The experimental results reveal that there is approximately equality in terms of efficiency between the new 32-type short cylindrical cup-shaped harmonic reducer and the conventional 32-type harmonic reducer. The volume of the flexspline of the new 32-type short cylindrical cup-shaped harmonic reducer is reduced by approximately 30% through multi-objective optimization. When the new 32-type short cylindrical cup-shaped harmonic reducer is used on the wheel of a rover prototype,the mass of the wheel hub is decreased by 0.42 kg. Test analysis of wheel motion verifies that the new 32-type short cylindrical cup-shaped harmonic reducer can meet the requirements regarding bearing capacity and efficiency.展开更多
Three new silica gel modified with calix[4]arene derivatives （p-tert-butyl-calix[4]arene （PC4）, calix[4]arene （C4） and calix[4]arene sulfonate （C4S）） have been prepared via modification of activated silica gel...Three new silica gel modified with calix[4]arene derivatives （p-tert-butyl-calix[4]arene （PC4）, calix[4]arene （C4） and calix[4]arene sulfonate （C4S）） have been prepared via modification of activated silica gel with toluene 2,4-di-iso-cyanate （TDI） as linker in tow step. The modified silica were characterized by fourier transform infrared spectroscopy （FT1R）, thermal analysis （TGA） and elemental analysis. The FTIR spectra and TGA analysis verified that the calix[4]arene derivates are covalent attached to the silica. Scanning electron microscope SEM and Brunauer-Emmett-Teller BET analysis have been done to get information about the sample＇s surface shape and area. SEM and BET analysis reveal that the modified silica are in the range of microporous adsorbent.展开更多
A series of novel supramolecular organocatalysts of hydroxyprolinamide based on the upper rim of calix[4]arene scaffold have been developed to catalyze enantioselective multi-component Biginelli reaction. Under the op...A series of novel supramolecular organocatalysts of hydroxyprolinamide based on the upper rim of calix[4]arene scaffold have been developed to catalyze enantioselective multi-component Biginelli reaction. Under the optimal conditions, the reactions occurred with moderate-to-excellent enantioselectivities (up to 98% ee). A plausible transition state constructed by the supra- molecular interaction of hydrogen bond and cation-π between catalysts and substrates has been proposed.展开更多
A general exchange pair approach is developed to identify the limiting distribution for any sequence of random variables, by calculating the conditional mean and the conditional second moments. The error of approximat...A general exchange pair approach is developed to identify the limiting distribution for any sequence of random variables, by calculating the conditional mean and the conditional second moments. The error of approximation is also studied. In particular, a Berry-Esseen type bound of O(n^(-3/4)) is obtained for the Curie-Weiss model at the critical temperature.展开更多
基金Project(2010DFR70270) supported by the International Science and Technology Cooperation Project with RussiaProjects(50975059,61005080) supported by the National Natural Science Foundation of China+2 种基金Project(B07018) supported by "111" Program of ChinaProject(SKLRS200801A02) supported by the Foundation of State Key Laboratory of Robotics and System (Harbin Institute of Technology),ChinaProject(HIT2009061) supported by the Key Subject Laboratory Open Fund of China
文摘In order to obtain a new-type short cylindrical cup-shaped flexspline that can be applied to space mechanisms,the APDL language of ANSYS software was employed to develop a parameterized equivalent contact model between a flexspline and a wave generator. The validity of the parameterized equivalent contact model was verified by comparing the results of the analytic value of the contact model and the value calculated by the theoretical formula. The curvilinear trend of stress was obtained by changing the structural parameter of the flexspline. Based on the curvilinear trend of stress,multi-objective optimizations of key structural parameters were achieved. Flexspline,wave generator,and circular spline of a new 32-type short cylindrical cup-shaped harmonic reducer were designed and manufactured. A performance test bench to carry out tests on the harmonic reducer was designed. Contrast experiments were implemented to determine the efficiency of the new 32-type short cylindrical cup-shaped harmonic reducer and the conventional 32-type harmonic reducer under different conditions. The experimental results reveal that there is approximately equality in terms of efficiency between the new 32-type short cylindrical cup-shaped harmonic reducer and the conventional 32-type harmonic reducer. The volume of the flexspline of the new 32-type short cylindrical cup-shaped harmonic reducer is reduced by approximately 30% through multi-objective optimization. When the new 32-type short cylindrical cup-shaped harmonic reducer is used on the wheel of a rover prototype,the mass of the wheel hub is decreased by 0.42 kg. Test analysis of wheel motion verifies that the new 32-type short cylindrical cup-shaped harmonic reducer can meet the requirements regarding bearing capacity and efficiency.
文摘Three new silica gel modified with calix[4]arene derivatives （p-tert-butyl-calix[4]arene （PC4）, calix[4]arene （C4） and calix[4]arene sulfonate （C4S）） have been prepared via modification of activated silica gel with toluene 2,4-di-iso-cyanate （TDI） as linker in tow step. The modified silica were characterized by fourier transform infrared spectroscopy （FT1R）, thermal analysis （TGA） and elemental analysis. The FTIR spectra and TGA analysis verified that the calix[4]arene derivates are covalent attached to the silica. Scanning electron microscope SEM and Brunauer-Emmett-Teller BET analysis have been done to get information about the sample＇s surface shape and area. SEM and BET analysis reveal that the modified silica are in the range of microporous adsorbent.
基金financial support from the National Natural Science Foundation of China (21002009, 21072093 & 20872051)the Doctoral Fund of Ministry of Education of China (20090091110017)+1 种基金Priority Academic Program Development of Jiangsu Higher Education Institutionsalso supported by the Fundamental Research Funds for the Central Universities (1107020526 & 1103020505)
文摘A series of novel supramolecular organocatalysts of hydroxyprolinamide based on the upper rim of calix[4]arene scaffold have been developed to catalyze enantioselective multi-component Biginelli reaction. Under the optimal conditions, the reactions occurred with moderate-to-excellent enantioselectivities (up to 98% ee). A plausible transition state constructed by the supra- molecular interaction of hydrogen bond and cation-π between catalysts and substrates has been proposed.
基金supported by Hong Kong Research Grants Council General Research Fund (Grant Nos. 403513 and 14302515)
文摘A general exchange pair approach is developed to identify the limiting distribution for any sequence of random variables, by calculating the conditional mean and the conditional second moments. The error of approximation is also studied. In particular, a Berry-Esseen type bound of O(n^(-3/4)) is obtained for the Curie-Weiss model at the critical temperature.
