Since 1994, the vertical directional solidification （VDS） technique is employed for the growths of bulk crystals-without the seed, without contact to the ampoule wall, without coating and without external pressure, ...Since 1994, the vertical directional solidification （VDS） technique is employed for the growths of bulk crystals-without the seed, without contact to the ampoule wall, without coating and without external pressure, which leads to the detached growth. Growth velocities ranged from 3 mm/h to 10 mm/h, and rotation rates 10-20 rpm have been used. Ingots, 10-20 mm diameter and 60-65 mm length, have been grown with the conical ampoule geometry and these ingots have shown symmetric detachment. Crystals grown under such conditions showed the relatively low dislocation density and the highest carrier mobility,/tn = 5.9 x 104 cm2＂Vl-sl than the crystal grown ever. For the detached crystals, the dislocation density is 104 cm＂2 in conical region, and reached less than 103 cm-2 in the direction of the growth, when the ingots are not in contact with the ampoule wall. Experiments for indium-antimonide （InSb） growth have shown that the 80% growth environments have detachment, 15% entrapped in conical region and 5% attached.展开更多
Because of the significance to the formation and evolution of the Tibetan plateau, the displacement and slip rate of the Altyn Tagh fault have been topics full of disputation. Scientists who hold different opinions on...Because of the significance to the formation and evolution of the Tibetan plateau, the displacement and slip rate of the Altyn Tagh fault have been topics full of disputation. Scientists who hold different opinions on the evolution of Tibet insist on different slip rates and displacements of the fault zone. In the article, study is focused on the late Quaternary slip rate of the Altyn Tagh fault west of the Cherchen River (between 85°E and 85°45’E). On the basis of high resolution SPOT images of the region, three sites, namely Koramlik, Aqqan pasture and Dalakuansay, were chosen for field investigation. To calculate the slip rate of the fault, displacement of terraces was measured on SPOT satellite images or in situ during fieldwork and thermo-luminescence (TL) dating method was used. To get the ages of terraces, samples of sand were collected from the uppermost sand beds that lie just under loess. The method for calculating slip rate of fault is to divide the displacement of terrace risers by the age of its neighboring lower terrace. The displacement of rivers is not considered in this article because of its uncertainties. At Koramlik, the slip rate of the Altyn Tagh fault is 11.6±2.6mm/a since 6.02±0.47ka B.P and 9.6±2.6mm/a since 15.76±1.19ka B.P. At Aqqan pasture, about 30km west of Koramlik, the slip rate is 12.1±1.9mm/a since 2.06±0.16 ka B.P. At Dalakuansayi, the slip rate of the fault is 12.2±3.0mm/a since 4.91±0.39ka B.P. Hence, we get the average slip rate of 11.4±2.5mm/a for the western part of the Altyn Tagh Fault since Holocene. This result is close to the latest results from GPS research.展开更多
The influence of the purity degree of the commercial aluminium on the mechanical properties： elastic stress, tensile strength, Brinell hardness, resilience and elongation at break was investigated. It was found that ...The influence of the purity degree of the commercial aluminium on the mechanical properties： elastic stress, tensile strength, Brinell hardness, resilience and elongation at break was investigated. It was found that the first three resistance characteristics decrease with the growth of the purity of the material chosen to the detriment of two ductility characteristics that rise to the three states considered： crude of casting noted： F, Annealed noted： O, hardened noted ： H1/4. Furthermore, it is important to note that the hardened and the annealed lead respectively to a considerable hardening and a considerable softening. This hardening and this softening of the material in question can be respectively associated with the increase in dislocation density and immigration impurity elements of dislocations.展开更多
We used panel data for 31 Chinese provinces from 2001 to 2009 and entropy methods to evaluate regional tourism resources endowment.Combined with regional tourism revenue,we constructed an asynchronous index and quanti...We used panel data for 31 Chinese provinces from 2001 to 2009 and entropy methods to evaluate regional tourism resources endowment.Combined with regional tourism revenue,we constructed an asynchronous index and quantitatively evaluated every area＇s asynchronous phenomenon regarding tourism resources.We found that Chinese mainland tourism resources have asynchronous phenomenon： tourism is positively asynchronous in the east（Yangtze River Delta,Pearl River Delta and Beijing-Tianjin region） and negatively asynchronous in central and western China.The total efficiency of tourism resources in eastern China is mainly driven by pure technology efficiency and by scale efficiency in western China.In addition to some provinces,the ranking of provincial total efficiency and the asynchronous index has a strong positive correlation.We conclude with several suggestions for the development of tourism resources across China.展开更多
In this paper an analytical method is proposed to investigate the vibration and power flows of periodically reinforced plate with general boundary conditions. Both the plate and stiffening beams are modeled as 3D stru...In this paper an analytical method is proposed to investigate the vibration and power flows of periodically reinforced plate with general boundary conditions. Both the plate and stiffening beams are modeled as 3D structural components, and the couplings at the interfaces are specified in terms of 3D elastic joints. The displacement function for each stiffening beam is expressed as a modified Fourier cosine series, and the transverse and in-plane displacements for the plate are similarly expressed as the 2D versions of the modified Fourier cosine series expansions. The unknown Fourier coefficients are calculated using the Rayleigh-Ritz technique. The key advantages of the proposed method include: 1) it is capable of dealing with arbitrary boundary and coupling conditions, 2) it allows modeling any number of reinforcing beams with arbitrary lengths, and 3) the structural intensity, power flows, and kinetic energy distributions are readily calculated analytically from the displacement functions through appropriate mathematical (differential) operations, to name a few. The power flow characteristics of periodically reinforced plates are studied against various influencing factors, such as, plate and beam boundary conditions, coupling conditions, excitation locations, and dislocations resulting from minor misplacement of a reinforcing beam.展开更多
文摘Since 1994, the vertical directional solidification （VDS） technique is employed for the growths of bulk crystals-without the seed, without contact to the ampoule wall, without coating and without external pressure, which leads to the detached growth. Growth velocities ranged from 3 mm/h to 10 mm/h, and rotation rates 10-20 rpm have been used. Ingots, 10-20 mm diameter and 60-65 mm length, have been grown with the conical ampoule geometry and these ingots have shown symmetric detachment. Crystals grown under such conditions showed the relatively low dislocation density and the highest carrier mobility,/tn = 5.9 x 104 cm2＂Vl-sl than the crystal grown ever. For the detached crystals, the dislocation density is 104 cm＂2 in conical region, and reached less than 103 cm-2 in the direction of the growth, when the ingots are not in contact with the ampoule wall. Experiments for indium-antimonide （InSb） growth have shown that the 80% growth environments have detachment, 15% entrapped in conical region and 5% attached.
文摘Because of the significance to the formation and evolution of the Tibetan plateau, the displacement and slip rate of the Altyn Tagh fault have been topics full of disputation. Scientists who hold different opinions on the evolution of Tibet insist on different slip rates and displacements of the fault zone. In the article, study is focused on the late Quaternary slip rate of the Altyn Tagh fault west of the Cherchen River (between 85°E and 85°45’E). On the basis of high resolution SPOT images of the region, three sites, namely Koramlik, Aqqan pasture and Dalakuansay, were chosen for field investigation. To calculate the slip rate of the fault, displacement of terraces was measured on SPOT satellite images or in situ during fieldwork and thermo-luminescence (TL) dating method was used. To get the ages of terraces, samples of sand were collected from the uppermost sand beds that lie just under loess. The method for calculating slip rate of fault is to divide the displacement of terrace risers by the age of its neighboring lower terrace. The displacement of rivers is not considered in this article because of its uncertainties. At Koramlik, the slip rate of the Altyn Tagh fault is 11.6±2.6mm/a since 6.02±0.47ka B.P and 9.6±2.6mm/a since 15.76±1.19ka B.P. At Aqqan pasture, about 30km west of Koramlik, the slip rate is 12.1±1.9mm/a since 2.06±0.16 ka B.P. At Dalakuansayi, the slip rate of the fault is 12.2±3.0mm/a since 4.91±0.39ka B.P. Hence, we get the average slip rate of 11.4±2.5mm/a for the western part of the Altyn Tagh Fault since Holocene. This result is close to the latest results from GPS research.
文摘The influence of the purity degree of the commercial aluminium on the mechanical properties： elastic stress, tensile strength, Brinell hardness, resilience and elongation at break was investigated. It was found that the first three resistance characteristics decrease with the growth of the purity of the material chosen to the detriment of two ductility characteristics that rise to the three states considered： crude of casting noted： F, Annealed noted： O, hardened noted ： H1/4. Furthermore, it is important to note that the hardened and the annealed lead respectively to a considerable hardening and a considerable softening. This hardening and this softening of the material in question can be respectively associated with the increase in dislocation density and immigration impurity elements of dislocations.
基金National Natural Science Foundation of China(4127114941301145)+1 种基金a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Youth Foundation of Humanities and Social Science of Education Ministry(12YJC790175)
文摘We used panel data for 31 Chinese provinces from 2001 to 2009 and entropy methods to evaluate regional tourism resources endowment.Combined with regional tourism revenue,we constructed an asynchronous index and quantitatively evaluated every area＇s asynchronous phenomenon regarding tourism resources.We found that Chinese mainland tourism resources have asynchronous phenomenon： tourism is positively asynchronous in the east（Yangtze River Delta,Pearl River Delta and Beijing-Tianjin region） and negatively asynchronous in central and western China.The total efficiency of tourism resources in eastern China is mainly driven by pure technology efficiency and by scale efficiency in western China.In addition to some provinces,the ranking of provincial total efficiency and the asynchronous index has a strong positive correlation.We conclude with several suggestions for the development of tourism resources across China.
文摘In this paper an analytical method is proposed to investigate the vibration and power flows of periodically reinforced plate with general boundary conditions. Both the plate and stiffening beams are modeled as 3D structural components, and the couplings at the interfaces are specified in terms of 3D elastic joints. The displacement function for each stiffening beam is expressed as a modified Fourier cosine series, and the transverse and in-plane displacements for the plate are similarly expressed as the 2D versions of the modified Fourier cosine series expansions. The unknown Fourier coefficients are calculated using the Rayleigh-Ritz technique. The key advantages of the proposed method include: 1) it is capable of dealing with arbitrary boundary and coupling conditions, 2) it allows modeling any number of reinforcing beams with arbitrary lengths, and 3) the structural intensity, power flows, and kinetic energy distributions are readily calculated analytically from the displacement functions through appropriate mathematical (differential) operations, to name a few. The power flow characteristics of periodically reinforced plates are studied against various influencing factors, such as, plate and beam boundary conditions, coupling conditions, excitation locations, and dislocations resulting from minor misplacement of a reinforcing beam.
