Think tanks as an important force in the policy making field in the United States have strengthened their visibility and expanded their influence in recent decades. This paper contends that the historical and politica...Think tanks as an important force in the policy making field in the United States have strengthened their visibility and expanded their influence in recent decades. This paper contends that the historical and political climate of the United States has fostered the development of think tanks and they will continue to exert their influence in the policy making field of the United States. It mainly examines the history of American think tanks and the roles they have been performing during more than one hundred years＇ evolution. In the twenty-first century, in a more and more flattering world, policy issues become increasingly complicated, therefore think tanks are indeed fixtures of American policy making scene. They play six major roles （1） source for policy idea; （2） venue for communicating and initiating new policy ideas; （3） source for personnel; （4） educating and informing the public; （5） evaluator of government policies; and （6） Track lI diplomacy.展开更多
The problem of collecting solar energy and increasing its efficiency was studied in this paper. It was discovered that a 3DPV （three-dimensional photovoltaic） structures can generate greater amounts of measured ener...The problem of collecting solar energy and increasing its efficiency was studied in this paper. It was discovered that a 3DPV （three-dimensional photovoltaic） structures can generate greater amounts of measured energy densities than stationary flat PV panels （rate： 2 to 20）. It has been found that the same structures work better not only because they are made in 3D but because PV panels do not have linear dependency on geometry. It seems that the conversion efficiency depends on the process of absorption of the solar energy, too, or in other words on the E. Yablonovich limit. The findings suggest that the quantity of material of solar panels may be reduced to generate the same amount of electricity.展开更多
Based on data from ChinaFLUX this study analyzed the daily value flow processes of carbon fixation, monthly value distribution, and daily accumulative processes in a year of two kinds of typical forest, two kinds of g...Based on data from ChinaFLUX this study analyzed the daily value flow processes of carbon fixation, monthly value distribution, and daily accumulative processes in a year of two kinds of typical forest, two kinds of grasses and a farmland. The results showed that the annual value of carbon fixation of these ecosystems was different, and flow processes and cumulative processes followed different trends over a year. The sequence of the five kinds of ecosystems based on the annual value of carbon fixation from largest to smallest was Yucheng warm temperate agriculture ecosystem （Yucheng）, Qianyanzhou subtropical artificial coniferous forest ecosystem （Qianyanzhou）, Changbai Mountain temperate mixed coniferous broad-leaved forest ecosystem （Changbaishan）, Haibei alpine meadow ecosystem （Haibei）and Dangxiong alpine meadow ecosystem （Dangxiong）. Variability in the daily and monthly carbon fixation at Qianyanzhou was the smallest, followed by Changbaishan, Yucheng, Dangxiong and Haibei. The cumulative processes of daily carbon fixation for the five kinds of ecosystems were well fitted to cubic curves.展开更多
The mechanism of grain structure evolution during directional solidification is a fundamental subject in material science. Within the published research there exist conflicting views on the mechanism of grain overgrow...The mechanism of grain structure evolution during directional solidification is a fundamental subject in material science. Within the published research there exist conflicting views on the mechanism of grain overgrowth. To study the effect of solidification rate on grain structure evolution, bi-crystals samples were produced in a nickel-base superalloy at different solidification rates. It was found that at the convergent grain boundaries those grains better aligned with respect to the heat flux more readily overgrew neighbouring grains with misaligned orientations and the effect became more pronounced as solidification rate was increased. However, at diverging grain boundaries the rate of overgrowth was invariant to the solidification rate. These experimental results were compared with models in the literature. Thus, a better insight into competitive grain growth in directional solidification processes was obtained.展开更多
For an n-variable Boolean function, there are 2n fixed polarity Reed-Muller(FPRM) forms. In this paper, a frame of power dissipation estimation for FPRM functions ispresented and the polarity conversion is introduced ...For an n-variable Boolean function, there are 2n fixed polarity Reed-Muller(FPRM) forms. In this paper, a frame of power dissipation estimation for FPRM functions ispresented and the polarity conversion is introduced to minimize the power for FPRM functions.Based on searching the best polarity for low power dissipation, an optimal algorithm is proposedand implemented in C. The algorithm is tested on seven single output functions from MCNCbenchmark circuits. The experimental results are shown in this paper.展开更多
Guide wire plays an important role in the fixation of femoral neck fracture with dynamic hip screw （DHS）. Breakage of a guide wire during operation is a very rare condition. We met such a dilemma in DHS fixation of ...Guide wire plays an important role in the fixation of femoral neck fracture with dynamic hip screw （DHS）. Breakage of a guide wire during operation is a very rare condition. We met such a dilemma in DHS fixation of a 54-year-old male patient who sustained Garden type IV frac- ture of the right femoral neck. The distal end of the guide wire broke and was entrapped in the fractured femoral neck. We tried to get the broken part out by a cannulated drill. Reaming was started with the cannulated drill slowly rotat- ing arotmd the guide K-wire until the reamer fully contained the target under fluoroscope. A bone curette was used to get the broken wire out but failed, so we had to use the cannuated drill to dredge this bone tunnel. Finally the bro-ken wire end was taken out, mixed with blood and bone fragments. Through the existing drilling channel, DHS fixa- tion was easily finished. The patient had an uneventful re- covery without avascular necrosis of femoral head or non- union of the fracture at one year＇s follow-up. A few methods can be adopted to deal with the broken guide wire. The way used in our case is less invasive but technically challenging. When the guide wire is properly positioned, this method is very practical and useful.展开更多
Following work carried out earlier on linear-quadratic optimal control for linear finitedimensional stationary systems we report,in this article,on extension of some of those results to certaininfinite dimensional sys...Following work carried out earlier on linear-quadratic optimal control for linear finitedimensional stationary systems we report,in this article,on extension of some of those results to certaininfinite dimensional systems;in particular a class of PDE systems of elliptic type.These systems arestudied in the now familiar framework developed by J.L.Lions and E.Magenes,specialized to asubclass of such systems important in a variety of applications.As an extended example this paperstudies an optimal redistribution problem in a groundwater flow system governed by Darcy's equation,presenting both analytic and computational work related to such problems.展开更多
文摘Think tanks as an important force in the policy making field in the United States have strengthened their visibility and expanded their influence in recent decades. This paper contends that the historical and political climate of the United States has fostered the development of think tanks and they will continue to exert their influence in the policy making field of the United States. It mainly examines the history of American think tanks and the roles they have been performing during more than one hundred years＇ evolution. In the twenty-first century, in a more and more flattering world, policy issues become increasingly complicated, therefore think tanks are indeed fixtures of American policy making scene. They play six major roles （1） source for policy idea; （2） venue for communicating and initiating new policy ideas; （3） source for personnel; （4） educating and informing the public; （5） evaluator of government policies; and （6） Track lI diplomacy.
文摘The problem of collecting solar energy and increasing its efficiency was studied in this paper. It was discovered that a 3DPV （three-dimensional photovoltaic） structures can generate greater amounts of measured energy densities than stationary flat PV panels （rate： 2 to 20）. It has been found that the same structures work better not only because they are made in 3D but because PV panels do not have linear dependency on geometry. It seems that the conversion efficiency depends on the process of absorption of the solar energy, too, or in other words on the E. Yablonovich limit. The findings suggest that the quantity of material of solar panels may be reduced to generate the same amount of electricity.
基金National Natural Science Foundation of China (31070384)
文摘Based on data from ChinaFLUX this study analyzed the daily value flow processes of carbon fixation, monthly value distribution, and daily accumulative processes in a year of two kinds of typical forest, two kinds of grasses and a farmland. The results showed that the annual value of carbon fixation of these ecosystems was different, and flow processes and cumulative processes followed different trends over a year. The sequence of the five kinds of ecosystems based on the annual value of carbon fixation from largest to smallest was Yucheng warm temperate agriculture ecosystem （Yucheng）, Qianyanzhou subtropical artificial coniferous forest ecosystem （Qianyanzhou）, Changbai Mountain temperate mixed coniferous broad-leaved forest ecosystem （Changbaishan）, Haibei alpine meadow ecosystem （Haibei）and Dangxiong alpine meadow ecosystem （Dangxiong）. Variability in the daily and monthly carbon fixation at Qianyanzhou was the smallest, followed by Changbaishan, Yucheng, Dangxiong and Haibei. The cumulative processes of daily carbon fixation for the five kinds of ecosystems were well fitted to cubic curves.
基金supported by the National Natural Science Foundation of China (Grant Nos. U1037601 and 50931004)the National Basic Research Program of China (Grant No. 2010CB631206)the Program of "One Hundred Talented People" of the Chinese Academy of Sciences
文摘The mechanism of grain structure evolution during directional solidification is a fundamental subject in material science. Within the published research there exist conflicting views on the mechanism of grain overgrowth. To study the effect of solidification rate on grain structure evolution, bi-crystals samples were produced in a nickel-base superalloy at different solidification rates. It was found that at the convergent grain boundaries those grains better aligned with respect to the heat flux more readily overgrew neighbouring grains with misaligned orientations and the effect became more pronounced as solidification rate was increased. However, at diverging grain boundaries the rate of overgrowth was invariant to the solidification rate. These experimental results were compared with models in the literature. Thus, a better insight into competitive grain growth in directional solidification processes was obtained.
文摘For an n-variable Boolean function, there are 2n fixed polarity Reed-Muller(FPRM) forms. In this paper, a frame of power dissipation estimation for FPRM functions ispresented and the polarity conversion is introduced to minimize the power for FPRM functions.Based on searching the best polarity for low power dissipation, an optimal algorithm is proposedand implemented in C. The algorithm is tested on seven single output functions from MCNCbenchmark circuits. The experimental results are shown in this paper.
文摘Guide wire plays an important role in the fixation of femoral neck fracture with dynamic hip screw （DHS）. Breakage of a guide wire during operation is a very rare condition. We met such a dilemma in DHS fixation of a 54-year-old male patient who sustained Garden type IV frac- ture of the right femoral neck. The distal end of the guide wire broke and was entrapped in the fractured femoral neck. We tried to get the broken part out by a cannulated drill. Reaming was started with the cannulated drill slowly rotat- ing arotmd the guide K-wire until the reamer fully contained the target under fluoroscope. A bone curette was used to get the broken wire out but failed, so we had to use the cannuated drill to dredge this bone tunnel. Finally the bro-ken wire end was taken out, mixed with blood and bone fragments. Through the existing drilling channel, DHS fixa- tion was easily finished. The patient had an uneventful re- covery without avascular necrosis of femoral head or non- union of the fracture at one year＇s follow-up. A few methods can be adopted to deal with the broken guide wire. The way used in our case is less invasive but technically challenging. When the guide wire is properly positioned, this method is very practical and useful.
文摘Following work carried out earlier on linear-quadratic optimal control for linear finitedimensional stationary systems we report,in this article,on extension of some of those results to certaininfinite dimensional systems;in particular a class of PDE systems of elliptic type.These systems arestudied in the now familiar framework developed by J.L.Lions and E.Magenes,specialized to asubclass of such systems important in a variety of applications.As an extended example this paperstudies an optimal redistribution problem in a groundwater flow system governed by Darcy's equation,presenting both analytic and computational work related to such problems.
