Visible light-induced two-step overall water-splitting was achieved by combining two types of photocatalysts, which were prepared by introducing foreign elements into rutile titanium dioxide (TiO2) and strontium titan...Visible light-induced two-step overall water-splitting was achieved by combining two types of photocatalysts, which were prepared by introducing foreign elements into rutile titanium dioxide (TiO2) and strontium titanate (SrTiO3) with a controlled electronic band structure. Rutile TiO2 and SrTiO3 were doped with chromium and tantalum (Cr,Ta-TiO2) and with rhodium (Rh-SrTiO3), respectively, to introduce visible-light sensitivity. Under irradiation with only visible light from a 420-nm LED lamp, the simultaneous liberation of hydrogen and oxygen with a molar ratio of ~2:1 was achieved with these two types of photocatalysts in the presence of iodate ion/iodide ion as a redox mediator.展开更多
In this paper the transient two-phase flow equations and their eigenvalues are first introduced. The flux vector is then split into subvectors which just contain a specially signed eigenvalue. Using one-sided spatial ...In this paper the transient two-phase flow equations and their eigenvalues are first introduced. The flux vector is then split into subvectors which just contain a specially signed eigenvalue. Using one-sided spatial difference operators finite difference equations and their solutions are obtained. Finally comparison with experiment shows the predicted results produce good agreement with experimental data.展开更多
For compressible two-phase displacement problem, a kind of upwind operator splitting finite difference schemes is put forward and make use of operator splitting, of calculus of variations, multiplicative commutation r...For compressible two-phase displacement problem, a kind of upwind operator splitting finite difference schemes is put forward and make use of operator splitting, of calculus of variations, multiplicative commutation rule of difference operators, decomposition of high order difference operators and prior estimates are adopted. Optimal order estimates in L 2 norm are derived to determine the error, in the approximate solution.展开更多
We identify two interrelated but independent species of microcracks with different origins and different distributions. One species is the classic high-stress microcracks identified in laboratory stress-cells associat...We identify two interrelated but independent species of microcracks with different origins and different distributions. One species is the classic high-stress microcracks identified in laboratory stress-cells associated with acoustic emissions as microcracks open with increasing stress. The other species is the low-stress distributions of closely-spaced stress-aligned fluid-saturated microcracks that observations of shear-wave splitting(SWS) demonstrate pervade almost all in situ rocks in the upper crust, the lower crust, and the uppermost 400 km of the mantle. On some occasions these two sets of microcracks may be interrelated and similar(hence ‘species') but they typically have fundamentally-different properties, different distributions, and different implications. The importance for hydrocarbon exploration and recovery is that SWS in hydrocarbon reservoirs monitors crack alignments and preferred directions of fluid-flow. The importance for earthquake seismology is that SWS above small earthquakes monitors the effects of increasing stress on the pervasive low-stress microcrack distributions so that stress-accumulation before, possibly distant, earthquakes can be recognised and impending earthquakes stress-forecast.展开更多
Due to the rapidly increasing demand for energy and environmental sustainability, stable and economical hydrogen production has received increasing attention in the past decades. In this regard, hydrogen production th...Due to the rapidly increasing demand for energy and environmental sustainability, stable and economical hydrogen production has received increasing attention in the past decades. In this regard, hydrogen production through photo-or electrocatalytic water splitting has continued to gain ever-growing interest. However, the existing catalysts are still unable to fulfill the demands of highefficiency, low-cost, and sustainable hydrogen production.Layered metal trichalcogenidophosphate(MPQ_3) is a newly developed two-dimensional material with tunable composition and electronic structure. Recently, MPQ_3 has been considered a promising candidate for clean energy generation and related water splitting applications. In this minireview, we firstly introduce the structure and methods for the synthesis of MPQ_3 materials. In the following sections, recent developments of MPQ_3 materials for photo-and electrocatalytic water splitting are briefly summarized. The roles of MPQ_3 materials in different reaction systems are also discussed. Finally, the challenges related to and prospects of MPQ_3 materials are presented on the basis of the current developments.展开更多
In order to eliminate mal-distribution and ensure the side arm to produce desirable gas quality a special distributor is proposed. The experimental distributor mainly consists of a straight through section,a gas extra...In order to eliminate mal-distribution and ensure the side arm to produce desirable gas quality a special distributor is proposed. The experimental distributor mainly consists of a straight through section,a gas extraction line,a liquid extraction line and a side arm branch. A gas orifice and a liquid orifice are mounted at the gas and liquid extraction line respectively to control the outlet gas quality. The diameter of the liquid orifice was set to 2. 50 mm and three gas orifices with different size( dG= 2. 65,5. 00,10. 00 mm) were tested. The experiments were carried out at an air-water two-phase flow loop. The gas superficial velocity ranged from 6. 0 to 20. 0 m /s and the liquid superficial velocity was in the range of 0. 02- 0. 18 m /s. Flow patterns such as wave flow,slug flow and annular flow were observed. The gas quality of the side arm branch was found mainly determined by the flow area ratio of the gas orifice to the liquid orifice and independent of gas and liquid superficial velocity,flow patterns and extraction flux.展开更多
In this paper, the boundary layer equations (abbreviation BLE) for exterior flow around an obstacle are established using semi-geodesic coordinate system (S-coordinate) based on the curved two dimensional surface of t...In this paper, the boundary layer equations (abbreviation BLE) for exterior flow around an obstacle are established using semi-geodesic coordinate system (S-coordinate) based on the curved two dimensional surface of the obstacle. BLE are nonlinear partial differential equations on unknown normal viscous stress tensor and pressure on the obstacle and the existence of solution of BLE is proved. In addition a dimensional split method for dimensional three Navier-Stokes equations is established by applying several 2D-3C partial differential equations on two dimensional manifolds to approach 3D Navier-Stokes equations. The examples for the exterior flow around spheroid and ellipsoid are presents here.展开更多
采用微波技术测量位移的方法,设计了一种基于开口环谐振器(Split Ring Resonator,SRR)的二维线性位移微波传感器。传感器由定子与动子两部分构成,其中定子由两组不同尺寸的SRR耦合一条传输微带线构成,动子采用单面覆铜的FR-4介质基板制...采用微波技术测量位移的方法,设计了一种基于开口环谐振器(Split Ring Resonator,SRR)的二维线性位移微波传感器。传感器由定子与动子两部分构成,其中定子由两组不同尺寸的SRR耦合一条传输微带线构成,动子采用单面覆铜的FR-4介质基板制成。动子二维移动时两个SRR的谐振频率将发生变化,传输零点也产生对应偏移,从而建立起位移和传输零点的关系。此外通过对SRR加载缺陷地结构,提高了检测灵敏度。经电磁建模和仿真,传感器在1 GHz至3.2 GHz范围内产生两个传输零点,可在x和y方向表征0~6 mm的位移,灵敏度分别为122 MHz/mm和82 MHz/mm。制作并测试了传感器实物,实测与仿真的数据基本吻合,证实了该传感器设计的有效性。展开更多
文摘Visible light-induced two-step overall water-splitting was achieved by combining two types of photocatalysts, which were prepared by introducing foreign elements into rutile titanium dioxide (TiO2) and strontium titanate (SrTiO3) with a controlled electronic band structure. Rutile TiO2 and SrTiO3 were doped with chromium and tantalum (Cr,Ta-TiO2) and with rhodium (Rh-SrTiO3), respectively, to introduce visible-light sensitivity. Under irradiation with only visible light from a 420-nm LED lamp, the simultaneous liberation of hydrogen and oxygen with a molar ratio of ~2:1 was achieved with these two types of photocatalysts in the presence of iodate ion/iodide ion as a redox mediator.
文摘In this paper the transient two-phase flow equations and their eigenvalues are first introduced. The flux vector is then split into subvectors which just contain a specially signed eigenvalue. Using one-sided spatial difference operators finite difference equations and their solutions are obtained. Finally comparison with experiment shows the predicted results produce good agreement with experimental data.
基金the Major State Basic Research Program of China(19990328)NNSF of China(19871051,19972039) the Doctorate Foundation of the State Education Commission
文摘For compressible two-phase displacement problem, a kind of upwind operator splitting finite difference schemes is put forward and make use of operator splitting, of calculus of variations, multiplicative commutation rule of difference operators, decomposition of high order difference operators and prior estimates are adopted. Optimal order estimates in L 2 norm are derived to determine the error, in the approximate solution.
基金This study was partially supported by the National Natural Science Foundation of China （No. 41174042）.
文摘We identify two interrelated but independent species of microcracks with different origins and different distributions. One species is the classic high-stress microcracks identified in laboratory stress-cells associated with acoustic emissions as microcracks open with increasing stress. The other species is the low-stress distributions of closely-spaced stress-aligned fluid-saturated microcracks that observations of shear-wave splitting(SWS) demonstrate pervade almost all in situ rocks in the upper crust, the lower crust, and the uppermost 400 km of the mantle. On some occasions these two sets of microcracks may be interrelated and similar(hence ‘species') but they typically have fundamentally-different properties, different distributions, and different implications. The importance for hydrocarbon exploration and recovery is that SWS in hydrocarbon reservoirs monitors crack alignments and preferred directions of fluid-flow. The importance for earthquake seismology is that SWS above small earthquakes monitors the effects of increasing stress on the pervasive low-stress microcrack distributions so that stress-accumulation before, possibly distant, earthquakes can be recognised and impending earthquakes stress-forecast.
基金Singapore Singapore MOE Tier 2 MOE2017-T2-2-069,MOE AcRF Tier 1 under Grant Nos.RG113/15 and 2016-T1-002-065Singapore EMA Project EIRP 12/NRF2015EWT-EIRP002-008National Research Foundation of Singapore (NRF) Investigatorship Award No.NRF2016NRF-NRFI001-22,National Research Foundation of Singapore (NRF) Investigatorship Award No. NRF2016NRF-NRFI00122
文摘Due to the rapidly increasing demand for energy and environmental sustainability, stable and economical hydrogen production has received increasing attention in the past decades. In this regard, hydrogen production through photo-or electrocatalytic water splitting has continued to gain ever-growing interest. However, the existing catalysts are still unable to fulfill the demands of highefficiency, low-cost, and sustainable hydrogen production.Layered metal trichalcogenidophosphate(MPQ_3) is a newly developed two-dimensional material with tunable composition and electronic structure. Recently, MPQ_3 has been considered a promising candidate for clean energy generation and related water splitting applications. In this minireview, we firstly introduce the structure and methods for the synthesis of MPQ_3 materials. In the following sections, recent developments of MPQ_3 materials for photo-and electrocatalytic water splitting are briefly summarized. The roles of MPQ_3 materials in different reaction systems are also discussed. Finally, the challenges related to and prospects of MPQ_3 materials are presented on the basis of the current developments.
基金Sponsored by the National Natural Science Foundation of China (Grant No.51006123)the Fundamental Research Funds for the Central Universities (Grant No.14CX05028A)
文摘In order to eliminate mal-distribution and ensure the side arm to produce desirable gas quality a special distributor is proposed. The experimental distributor mainly consists of a straight through section,a gas extraction line,a liquid extraction line and a side arm branch. A gas orifice and a liquid orifice are mounted at the gas and liquid extraction line respectively to control the outlet gas quality. The diameter of the liquid orifice was set to 2. 50 mm and three gas orifices with different size( dG= 2. 65,5. 00,10. 00 mm) were tested. The experiments were carried out at an air-water two-phase flow loop. The gas superficial velocity ranged from 6. 0 to 20. 0 m /s and the liquid superficial velocity was in the range of 0. 02- 0. 18 m /s. Flow patterns such as wave flow,slug flow and annular flow were observed. The gas quality of the side arm branch was found mainly determined by the flow area ratio of the gas orifice to the liquid orifice and independent of gas and liquid superficial velocity,flow patterns and extraction flux.
文摘In this paper, the boundary layer equations (abbreviation BLE) for exterior flow around an obstacle are established using semi-geodesic coordinate system (S-coordinate) based on the curved two dimensional surface of the obstacle. BLE are nonlinear partial differential equations on unknown normal viscous stress tensor and pressure on the obstacle and the existence of solution of BLE is proved. In addition a dimensional split method for dimensional three Navier-Stokes equations is established by applying several 2D-3C partial differential equations on two dimensional manifolds to approach 3D Navier-Stokes equations. The examples for the exterior flow around spheroid and ellipsoid are presents here.
