Mountain regions play an increasingly essential role in global sustainable development, and the related sustainable development issues have attracted increasing attention. There are obvious vertical spatial differenti...Mountain regions play an increasingly essential role in global sustainable development, and the related sustainable development issues have attracted increasing attention. There are obvious vertical spatial differentiation phenomena in both natural and socio-eeonomic fields with altitude being a key factor affecting the economic development of mountain regions. However, the exact influence of altitude is still unknown. Based on the county scale, this paper used the gravitational potential energy model to evaluate the effects of altitude on economic development in China. The results indicate that the high-altitude areas were the depression areas of county economic development, and county economic density showed a decreasing trend with the increase of altitude. County economic density respectively decreased by 0.10%, 0.04% and 0.02% with every 1% increase in altitude in 2000, 2005 and 2010. Here we demonstrate that high altitude has negative effect on county economy, although the negative effect presented a downward trend. The results also showed that increasing capital and labor investments could reduce the negative effect of high altitude on county economy. In 2010, with every 1% increase in capital and labor density, county economic density increased by 0.62% and 0.83%, respectively. The effects of altitude were the results of multidimensional factors. The fundamental approach to reduce the negative effects of high altitude is to combine the ecological environment and resources to develop characteristic industries. The construction of infrastructure should be strengthened, which can promote the occurrence of the contra-flow of people, logistics and capital, and promote the balanced development of county economy.展开更多
This paper is concerned with the hydroelastic problem of a very large pontoon-type floating structure(VLFS) edged with a pair of submerged horizontal plates, which is a combination of perforated and non-perforated pla...This paper is concerned with the hydroelastic problem of a very large pontoon-type floating structure(VLFS) edged with a pair of submerged horizontal plates, which is a combination of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. For the hydroelastic analysis, the fluid is assumed to be ideal and its motion is irrotational so that a velocity potential exists. The VLFS is modeled as an elastic plate according to the classical thin plate theory. The fluid-structure interaction problem is separated into conventional hydrodynamics and structure dynamics by using modal expansion method in the frequency-domain. It involves, firstly, the deflection of the VLFS, which is expressed by a superposition of modal functions and corresponding modal amplitudes. Then the boundary element method is used to solve the integral equations of diffraction and radiation on the body surface for the velocity potential, whereas the vibration equation is solved by the Galerkin's method for modal amplitudes, and then the deflection is obtained by the sum of multiplying modal functions with modal amplitudes. This study examines the effects of the width and location of the non-perforated horizontal plates on the hydroelastic response of the VLFS, then the performance of perforated plates is investigated to reduce the motion near the fore-end of the VLFS. Considering the advantages and disadvantages of submerged plates without and with cylindrical holes, we propose a simple anti-motion device, which is a combination of a pair of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. The effectiveness of this device in reducing the deformation and bending moment of the VLFS has been confirmed, and is compared with the results in cases without and with the submerged horizontal plates by the analysis in this paper.展开更多
Nonlinear Rossby waves in a Boussinesq fluid model which includes both the vertical and horizontalcomponents of Coriolis force are studied by using the semi-geostrophic approximation and the method of travelling-waves...Nonlinear Rossby waves in a Boussinesq fluid model which includes both the vertical and horizontalcomponents of Coriolis force are studied by using the semi-geostrophic approximation and the method of travelling-wavesolution.Taylor series expansion has been employed to isolate the characteristics of the linear Rossby waves and identifythe Rossby cnoidal and solitary waves.Qualitative analysis indicates that if the disturbances are independent of latitude,the effect of horizontal components of Coriolis force disappears.展开更多
Medicines are a global, strategic and diplomatic issue [1]. The UN General Secretary’s High Level Task Force [2] on Access to Medicines calls for a new approach to reduce the gap between medical innovations and acces...Medicines are a global, strategic and diplomatic issue [1]. The UN General Secretary’s High Level Task Force [2] on Access to Medicines calls for a new approach to reduce the gap between medical innovations and access to medicines. Inequality in access to quality pharmaceutical products in a framework of global health democracy poses a threat to the ethical and equitable management of the provision of quality health care, particularly during global health crises. In French-speaking Africa, the lack of a unified production of pharmaceutical medicines forces wholesalers （public and private） to import almost all of their medicine demands resulting in a risk of dependence and major pharmaceutical quality defects. These central purchasing units are therefore often faced with the major challenge of guaranteeing the performance of their services and the security of their supplies. In order to achieve component 3 （“Access to Health”） of the SDOs （sustainable development goals）, in particular the access to affordable medicines, it is essential for a country to have a strategy of pharmaceutical independence [3] by anticipating the epidemiological transition and the management of health crises. This strategy of pharmaceutical independence is based in the short and medium term on the strengthening of central purchasing units and the establishment of a public-private partnership between central purchasing units and wholesalers, and in the long term on the establishment of competitive production units that comply with international standards. However, recent health crises have shown the fragility of public central purchasing units and make it difficult to anticipate health crises.展开更多
This the continuation of[8].The main purpose ofth0 paper Is to gi、 both general formof any unitary extension and unitary dilation of a contraction of Π_k associated with its trianglemodel.
This paper studies the transient departure process of M^x/G/1 queueing system with single server vacation. We present a simple probability decomposition method to derive the expected number of departures occurring in ...This paper studies the transient departure process of M^x/G/1 queueing system with single server vacation. We present a simple probability decomposition method to derive the expected number of departures occurring in finite time interval from any initial state and the asymptotic expansion of the expected number. Especially, we derive some more practical results for some special cases.展开更多
A two-dimensional nonlinear shell model "of Koiter’s type" has recently been proposed by the first author. It is shown here that, according to two mutually exclusive sets of assumptions bearing on the assoc...A two-dimensional nonlinear shell model "of Koiter’s type" has recently been proposed by the first author. It is shown here that, according to two mutually exclusive sets of assumptions bearing on the associated manifold of admissible inextensional displacements, the leading term of a formal asymptotic expansion of the solution of this two-dimensional model, with the thickness as the "small’ parameter, satisfies either the two-dimensional equations of a nonlinearly elastic "membrane" shell or those of a nonlinearly elastic "flexural" shell. These conclusions being identical to those recently drawn by B. Miara, then by V. Lods and B. Miara, for the leading term of a formal asymptotic expansion of the solution of the equations of three-dimensional nonlinear elasticity, again with the thickness as the "small" parameter, the nonlinear shell model of Koiter’s type considered here is thus justified, at least formally.展开更多
基金funded by the National Natural Science Foundation of China (Grants No.41571523)the National Science and Technology Support Program (Grant No.2014BAC05B01)the National Key Basic Research and Development Program of China (973 Program) (Grant No.2013CBA01808)
文摘Mountain regions play an increasingly essential role in global sustainable development, and the related sustainable development issues have attracted increasing attention. There are obvious vertical spatial differentiation phenomena in both natural and socio-eeonomic fields with altitude being a key factor affecting the economic development of mountain regions. However, the exact influence of altitude is still unknown. Based on the county scale, this paper used the gravitational potential energy model to evaluate the effects of altitude on economic development in China. The results indicate that the high-altitude areas were the depression areas of county economic development, and county economic density showed a decreasing trend with the increase of altitude. County economic density respectively decreased by 0.10%, 0.04% and 0.02% with every 1% increase in altitude in 2000, 2005 and 2010. Here we demonstrate that high altitude has negative effect on county economy, although the negative effect presented a downward trend. The results also showed that increasing capital and labor investments could reduce the negative effect of high altitude on county economy. In 2010, with every 1% increase in capital and labor density, county economic density increased by 0.62% and 0.83%, respectively. The effects of altitude were the results of multidimensional factors. The fundamental approach to reduce the negative effects of high altitude is to combine the ecological environment and resources to develop characteristic industries. The construction of infrastructure should be strengthened, which can promote the occurrence of the contra-flow of people, logistics and capital, and promote the balanced development of county economy.
基金the National Science Foundation for Creative Re-search Groups of China (Grant No.50921001) for supporting this work
文摘This paper is concerned with the hydroelastic problem of a very large pontoon-type floating structure(VLFS) edged with a pair of submerged horizontal plates, which is a combination of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. For the hydroelastic analysis, the fluid is assumed to be ideal and its motion is irrotational so that a velocity potential exists. The VLFS is modeled as an elastic plate according to the classical thin plate theory. The fluid-structure interaction problem is separated into conventional hydrodynamics and structure dynamics by using modal expansion method in the frequency-domain. It involves, firstly, the deflection of the VLFS, which is expressed by a superposition of modal functions and corresponding modal amplitudes. Then the boundary element method is used to solve the integral equations of diffraction and radiation on the body surface for the velocity potential, whereas the vibration equation is solved by the Galerkin's method for modal amplitudes, and then the deflection is obtained by the sum of multiplying modal functions with modal amplitudes. This study examines the effects of the width and location of the non-perforated horizontal plates on the hydroelastic response of the VLFS, then the performance of perforated plates is investigated to reduce the motion near the fore-end of the VLFS. Considering the advantages and disadvantages of submerged plates without and with cylindrical holes, we propose a simple anti-motion device, which is a combination of a pair of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. The effectiveness of this device in reducing the deformation and bending moment of the VLFS has been confirmed, and is compared with the results in cases without and with the submerged horizontal plates by the analysis in this paper.
基金Supported by National Natural Science Foundation of China under Grant No.40475023
文摘Nonlinear Rossby waves in a Boussinesq fluid model which includes both the vertical and horizontalcomponents of Coriolis force are studied by using the semi-geostrophic approximation and the method of travelling-wavesolution.Taylor series expansion has been employed to isolate the characteristics of the linear Rossby waves and identifythe Rossby cnoidal and solitary waves.Qualitative analysis indicates that if the disturbances are independent of latitude,the effect of horizontal components of Coriolis force disappears.
文摘Medicines are a global, strategic and diplomatic issue [1]. The UN General Secretary’s High Level Task Force [2] on Access to Medicines calls for a new approach to reduce the gap between medical innovations and access to medicines. Inequality in access to quality pharmaceutical products in a framework of global health democracy poses a threat to the ethical and equitable management of the provision of quality health care, particularly during global health crises. In French-speaking Africa, the lack of a unified production of pharmaceutical medicines forces wholesalers （public and private） to import almost all of their medicine demands resulting in a risk of dependence and major pharmaceutical quality defects. These central purchasing units are therefore often faced with the major challenge of guaranteeing the performance of their services and the security of their supplies. In order to achieve component 3 （“Access to Health”） of the SDOs （sustainable development goals）, in particular the access to affordable medicines, it is essential for a country to have a strategy of pharmaceutical independence [3] by anticipating the epidemiological transition and the management of health crises. This strategy of pharmaceutical independence is based in the short and medium term on the strengthening of central purchasing units and the establishment of a public-private partnership between central purchasing units and wholesalers, and in the long term on the establishment of competitive production units that comply with international standards. However, recent health crises have shown the fragility of public central purchasing units and make it difficult to anticipate health crises.
文摘This the continuation of[8].The main purpose ofth0 paper Is to gi、 both general formof any unitary extension and unitary dilation of a contraction of Π_k associated with its trianglemodel.
基金This research is supported by Natural Science Foundation of the Education Department of Sichuan Province （[2006]A067） and the Talent Introduction Foundation of Sichuan Normal University. Acknowledgments The author thanks referees for their many helpful comments and suggestions for the improvement of this paper.
文摘This paper studies the transient departure process of M^x/G/1 queueing system with single server vacation. We present a simple probability decomposition method to derive the expected number of departures occurring in finite time interval from any initial state and the asymptotic expansion of the expected number. Especially, we derive some more practical results for some special cases.
文摘A two-dimensional nonlinear shell model "of Koiter’s type" has recently been proposed by the first author. It is shown here that, according to two mutually exclusive sets of assumptions bearing on the associated manifold of admissible inextensional displacements, the leading term of a formal asymptotic expansion of the solution of this two-dimensional model, with the thickness as the "small’ parameter, satisfies either the two-dimensional equations of a nonlinearly elastic "membrane" shell or those of a nonlinearly elastic "flexural" shell. These conclusions being identical to those recently drawn by B. Miara, then by V. Lods and B. Miara, for the leading term of a formal asymptotic expansion of the solution of the equations of three-dimensional nonlinear elasticity, again with the thickness as the "small" parameter, the nonlinear shell model of Koiter’s type considered here is thus justified, at least formally.
