In this work, the meridional variation of the thermal tropopause layer is investigated using high vertical resolution radiosonde measurements over China. A tropopause-based mean method is used to characterize the dept...In this work, the meridional variation of the thermal tropopause layer is investigated using high vertical resolution radiosonde measurements over China. A tropopause-based mean method is used to characterize the depth of the tropopause inversion layer （TIL）, and a curve-fitting method to profiles of Brunt-Vaisala frequency is applied to identify the transition sharpness of the static stability in the tropopause transition layer （TTL）.The eight radiosonde stations are grouped into four latitudinal bands at intervals of 7°. Analyses show that the tropopause at higher latitudes is much more likely to be sharp and have a strong TIL, while that at lower latitudes is dominated by a thick TTL.展开更多
This research work numerically analyzes 2D,steady state,mixed convective heat transfer for Newtonian fluids in lid driven square enclosure with centered triangular block（blockage—10%or 30%）maintained either at the ...This research work numerically analyzes 2D,steady state,mixed convective heat transfer for Newtonian fluids in lid driven square enclosure with centered triangular block（blockage—10%or 30%）maintained either at the constant wall temperature or constant heat flux thermal conditions.The fluid flow in the enclosure is initiated by top moving wall in＋x-direction,while all other walls are stationary.The top and bottom walls are thermally insulated.In particular,the governing field equations are solved for range of governing parameters such as,Reynolds number（1–1000）,Prandtl number（1–100）,and Grashof number展开更多
As a result of the left-lateral strike-slipping of the Altyn Tagh fault in Neotectonic period, a contra-rotational structure, namely the Zhaobishan vortex structure, has developed at the juncture of the main Altyn Tag...As a result of the left-lateral strike-slipping of the Altyn Tagh fault in Neotectonic period, a contra-rotational structure, namely the Zhaobishan vortex structure, has developed at the juncture of the main Altyn Tagh fault and the northern fringe fault of the Qilian Mountains. Preliminary analysis on the deformation and evolution of the Zhaobishan vortex structure. In combination with the previous data, suggests that the tectonic transform between the Altyn Tagh fault and the northern fringe fault of the Qilian Mountains attributes to the deformation of the rotational structure. The existence of a series of rotational structures along the Altyn Tagh fault and on the northeastern edge of the Qinghai-Xizang(Tibet) plateau indicate that as the substance in the northern Qinghai-Xizang (Tibet) plateau moves clockwise around the eastern tectonic knot of the Himalayas, rotational structures become the principal mode on the northern marginal zone of the Plateau of transforming and absorbing tectonic deformation.展开更多
The transverse symmetry transformations associated with the normal symmetry transformations are proposedto build the transverse constraints on the basic vertices in gauge theories.I show that,while the BRST symmetryin...The transverse symmetry transformations associated with the normal symmetry transformations are proposedto build the transverse constraints on the basic vertices in gauge theories.I show that,while the BRST symmetryin non-Abelian gauge theory QCD (Quantum Chromodynamics) leads to the Slavnov-Taylor identity for the quark-gluonvertex which constrains the longitudinal part of the vertex,the transverse symmetry transformation associated with theBRST symmetry enables to derive the transverse Slavnov-Taylor identity for the quark-gluon vertex,which constrainsthe transverse part of the quark-gluon vertex from the gauge symmetry of QCD.展开更多
A new type homogeneous planar PC （photoelectric converter） on the basis of multijunction semiconductor n＋-p-p＋-n＋-p-p＋-...-n＋-p-p＋ structure has been investigated. The entire structure is a cascade PC consisti...A new type homogeneous planar PC （photoelectric converter） on the basis of multijunction semiconductor n＋-p-p＋-n＋-p-p＋-...-n＋-p-p＋ structure has been investigated. The entire structure is a cascade PC consisting of a number of elements of the structure--single PCs connected in series and illuminated by light that has consistently passed through the previous semiconductor layers. The theory of converter of both monochromatic and solar radiation has been developed and the limiting values of their photoelectric and power characteristics have been determined, including the optimal thickness and number of single PCs layered on a base PC, their spectral sensitivity, current-voltage characteristics and efficiency. The open-circuit voltage grows practically linearly with the number of elements in the cascade. The top efficiency limit for a certain optimal elements number reaches its maximum that exceeds considerably that of the base PC, especially in the range of low collecting coefficient of charge carriers in the base PC.展开更多
A mesoscale weather research and forecasting(WRF)model was used to simulate a cold vortex that developed over Northeast China during June 19–23,2010.The simulation used high vertical resolution to reproduce the key f...A mesoscale weather research and forecasting(WRF)model was used to simulate a cold vortex that developed over Northeast China during June 19–23,2010.The simulation used high vertical resolution to reproduce the key features of the cold vortex development.Characteristics of the associated stratosphere-troposphere exchange(STE),specifically the spatiotemporal distribution of the cross-tropopause mass flux(CTF),were investigated using the Wei formula.The simulation results showed that the net mass exchange induced by the cold vortex was controlled by stratosphere-to-troposphere transport(STT)processes.In the pre-formation stage of the cold vortex(i.e.,the development of the trough and ridge),active exchange was evident.Over the lifecycle of the cold vortex,STT processes prevailed at the rear of the trough and moving vortex,whereas troposphere-to-stratosphere transport(TST)processes prevailed at the front end.This spatial pattern was caused by temporal fluctuations of the tropopause.However,because of the cancellation of the upward flux by the downward flux,the contribution of the tropopause fluctuation term to the net mass exchange was only minor.In this case,horizontal motion dominated the net mass exchange.The time evolution of the CTF exhibited three characteristics:(1)the predominance of the STT during the pre-formation stage;(2)the formation and development of the cold vortex,in which the CTF varied in a fluctuating pattern from TST to STT to TST;and(3)the prevalence of the STT during the decay stage.展开更多
We report the fabrication of CuI-Si heterojunction solar cells with carbon nanotubes （CNTs） as a transparent electrode. A flexible CNT network was transferred onto tile top of a polycrystalline CuI layer, making a c...We report the fabrication of CuI-Si heterojunction solar cells with carbon nanotubes （CNTs） as a transparent electrode. A flexible CNT network was transferred onto tile top of a polycrystalline CuI layer, making a conformal coating with good contact with the underlying CuI. The solar cells showed power conversion efficiencies in the range of 6% to 10.5%, while the efficiency degradation was less than 10% after the device was stored in air for 8 days. Compared with conventional rigid electrodes such as indium tin oxide （ITO） glass, the flexibility of the CNT films ensures better contact with the active layers and removes the need for press-contact electrodes. Degraded cells can recover their original performance by acid doping of the CNT electrode. Our results suggest that CNT films are suitable electrical contacts for rough materials and structures with an uneven surface.展开更多
基金funded by the National Natural Science Foundation of China[91337214],[41675040]
文摘In this work, the meridional variation of the thermal tropopause layer is investigated using high vertical resolution radiosonde measurements over China. A tropopause-based mean method is used to characterize the depth of the tropopause inversion layer （TIL）, and a curve-fitting method to profiles of Brunt-Vaisala frequency is applied to identify the transition sharpness of the static stability in the tropopause transition layer （TTL）.The eight radiosonde stations are grouped into four latitudinal bands at intervals of 7°. Analyses show that the tropopause at higher latitudes is much more likely to be sharp and have a strong TIL, while that at lower latitudes is dominated by a thick TTL.
文摘This research work numerically analyzes 2D,steady state,mixed convective heat transfer for Newtonian fluids in lid driven square enclosure with centered triangular block（blockage—10%or 30%）maintained either at the constant wall temperature or constant heat flux thermal conditions.The fluid flow in the enclosure is initiated by top moving wall in＋x-direction,while all other walls are stationary.The top and bottom walls are thermally insulated.In particular,the governing field equations are solved for range of governing parameters such as,Reynolds number（1–1000）,Prandtl number（1–100）,and Grashof number
文摘As a result of the left-lateral strike-slipping of the Altyn Tagh fault in Neotectonic period, a contra-rotational structure, namely the Zhaobishan vortex structure, has developed at the juncture of the main Altyn Tagh fault and the northern fringe fault of the Qilian Mountains. Preliminary analysis on the deformation and evolution of the Zhaobishan vortex structure. In combination with the previous data, suggests that the tectonic transform between the Altyn Tagh fault and the northern fringe fault of the Qilian Mountains attributes to the deformation of the rotational structure. The existence of a series of rotational structures along the Altyn Tagh fault and on the northeastern edge of the Qinghai-Xizang(Tibet) plateau indicate that as the substance in the northern Qinghai-Xizang (Tibet) plateau moves clockwise around the eastern tectonic knot of the Himalayas, rotational structures become the principal mode on the northern marginal zone of the Plateau of transforming and absorbing tectonic deformation.
基金Supported by National Natural Science Foundation of China under Grant Nos.90303006 and 10875174
文摘The transverse symmetry transformations associated with the normal symmetry transformations are proposedto build the transverse constraints on the basic vertices in gauge theories.I show that,while the BRST symmetryin non-Abelian gauge theory QCD (Quantum Chromodynamics) leads to the Slavnov-Taylor identity for the quark-gluonvertex which constrains the longitudinal part of the vertex,the transverse symmetry transformation associated with theBRST symmetry enables to derive the transverse Slavnov-Taylor identity for the quark-gluon vertex,which constrainsthe transverse part of the quark-gluon vertex from the gauge symmetry of QCD.
文摘A new type homogeneous planar PC （photoelectric converter） on the basis of multijunction semiconductor n＋-p-p＋-n＋-p-p＋-...-n＋-p-p＋ structure has been investigated. The entire structure is a cascade PC consisting of a number of elements of the structure--single PCs connected in series and illuminated by light that has consistently passed through the previous semiconductor layers. The theory of converter of both monochromatic and solar radiation has been developed and the limiting values of their photoelectric and power characteristics have been determined, including the optimal thickness and number of single PCs layered on a base PC, their spectral sensitivity, current-voltage characteristics and efficiency. The open-circuit voltage grows practically linearly with the number of elements in the cascade. The top efficiency limit for a certain optimal elements number reaches its maximum that exceeds considerably that of the base PC, especially in the range of low collecting coefficient of charge carriers in the base PC.
基金the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 41305038)
文摘A mesoscale weather research and forecasting(WRF)model was used to simulate a cold vortex that developed over Northeast China during June 19–23,2010.The simulation used high vertical resolution to reproduce the key features of the cold vortex development.Characteristics of the associated stratosphere-troposphere exchange(STE),specifically the spatiotemporal distribution of the cross-tropopause mass flux(CTF),were investigated using the Wei formula.The simulation results showed that the net mass exchange induced by the cold vortex was controlled by stratosphere-to-troposphere transport(STT)processes.In the pre-formation stage of the cold vortex(i.e.,the development of the trough and ridge),active exchange was evident.Over the lifecycle of the cold vortex,STT processes prevailed at the rear of the trough and moving vortex,whereas troposphere-to-stratosphere transport(TST)processes prevailed at the front end.This spatial pattern was caused by temporal fluctuations of the tropopause.However,because of the cancellation of the upward flux by the downward flux,the contribution of the tropopause fluctuation term to the net mass exchange was only minor.In this case,horizontal motion dominated the net mass exchange.The time evolution of the CTF exhibited three characteristics:(1)the predominance of the STT during the pre-formation stage;(2)the formation and development of the cold vortex,in which the CTF varied in a fluctuating pattern from TST to STT to TST;and(3)the prevalence of the STT during the decay stage.
基金This work is supported by the National Natural Science Foundation of China （NSFC, Grant No.50972067） and the 863 Program （No. 2009AA05Z423）. A. Cao acknowledges the support by the National Science Foundation of China （NSFC, No. 51072005） and C. Huang acknowledges NSFC No. 90922004 for financial support.
文摘We report the fabrication of CuI-Si heterojunction solar cells with carbon nanotubes （CNTs） as a transparent electrode. A flexible CNT network was transferred onto tile top of a polycrystalline CuI layer, making a conformal coating with good contact with the underlying CuI. The solar cells showed power conversion efficiencies in the range of 6% to 10.5%, while the efficiency degradation was less than 10% after the device was stored in air for 8 days. Compared with conventional rigid electrodes such as indium tin oxide （ITO） glass, the flexibility of the CNT films ensures better contact with the active layers and removes the need for press-contact electrodes. Degraded cells can recover their original performance by acid doping of the CNT electrode. Our results suggest that CNT films are suitable electrical contacts for rough materials and structures with an uneven surface.
