检索结果-南通市图书馆

Subsonic Euler flows in a divergent nozzle

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2014年第1期57卷 97-110页

作者： weng ShangKun Department of Mathematics Harvard University

We characterize a class of physical boundary conditions that guarantee the existence and uniqueness of the subsonic Euler flow in a general finitely long *** precisely,by prescribing the incoming flow angle and the Bernoulli’s function at the inlet and the end pressure at the exit of the nozzle,we establish an existence and uniqueness theorem for subsonic Euler flows in a 2-D nozzle,which is also required to be adjacent to some special background *** a result can also be extended to the 3-D asymmetric case.

关键词： subsonic flow,elliptic system of first order,hyperbolic-elliptic coupled

Constraints on what controls millennial-scale basin-wide denudation across mountain belts, Asia

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2025年第1期68卷 74-93页

作者： ye yANG Steven A.BINNIE Sheng XU Cong-Qiang LIU Tibor j.DUNAI Institute of Surface-Earth System Science School of Earth System Science Tianjin University Institute of Geology and Mineralogy University of Cologne

The terrestrial cosmogenic nuclide dataset consisting of 123310Be measurements of fluvial sediment samples across the Asian mountain belts is used to constrain the influence of climate,tectonics and topography on Earth-surface denudation processes.10Be-derived basin-wide denudation rates were recalculated using a Monte Carlo simulation approach that relied on pixel-by-pixel production *** rates derived span four orders of magnitude,from 7.4±0.7 mm kyr-1（1σ;Central Tibetan Plateau） to 9,646744+777mm kyr-1（1σ;Southern Tibetan Plateau）,with a median of 186 mm *** our results with the traditional basin-wide production rate scaling model using a centroid coordinate and mean elevation,suggests that 96.6%of production rates will be underestimated using the latter method,especially for basins with a large *** bias between both methods reaches as large as 40%,caused by basin hypsometry and the nonlinear scaling of production rate with elevation and *** of the correlations between uniformly recalculated denudation rates and tectonics,climate,topography and rock lithology will facilitate the extrapolation of denudation rates in unknown basins using available *** the perspective of local scales,precipitation coupled with neotectonics-driven landslides is likely the most influential factor in subtropical Taiwan Island,while topography primarily constrains surface denudation rates in the eastern Tibetan Plateau within a narrow range of *** highland regions with glacier coverage,such as the Pamir,central and southern Tibetan Plateau high denudation rates are affected by glaciation,whereas lower precipitation and high erosion base level may limit river incision and evolving relief in the Central Tibetan *** contrast to local-scale findings highlighting a dominant factor constraining denudation rate,our large-scale quantitative analyses across the Asian mountain belts finds that （1） topographic metrics including

关键词： 10Be-derived denudation rate Climate change Tectonic uplift Topographic gradient Asian mountains

Capture and electro-splitting of CO_2 in molten salts

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

journal of Energy Chemistry 2019年第1期28卷 128-143页

作者： Wei weng Lizi Tang Wei Xiao School of Resource and Environmental Sciences Hubei International Scientific and Technological Cooperation Base of Sustainable Resource and EnergyWuhan University

Due to the serious greenhouse gas effects caused by the increasing concentration of atmospheric CO_2,carbon capture and storage(CCS) has been an important area of research and many technologies are developed within this field. Molten salt CO_2 capture and electrochemical transformation(MSCC-ET) process is a desirable method due to a high CO_2 solubility, a wide potential window of molten salts and easily-controlled electrode reactions. Generally, electro-splitting CO_2 in molten salts begins with CO_2 absorption reactions to form CO_3^(2-), which is then followed by the carbon deposition at the cathode and O_2 evolution at the anode. As a result, CO_2 is electro-converted to O_2 and carbon with different morphologies, compositions, microstructures and functional properties. This report introduces the MSCC-ET process, summarizes the reactions occurring in the molten salts and at the electrode surfaces, as well as the morphological variations of the cathodic products. The inert anode materials, cost estimation and scale-up evaluation of the process are then discussed. It is presumed that with a comprehensive understanding of the electrode reactions during electrolysis and the functional properties of carbon materials obtained during CO_2 electro-splitting can provide a foundation for further developing this environmentally friendly process.

关键词： CO2 electro-splitting Molten salt electrolysis Inert anodes Cost evaluation

Unraveling Iterative Control Structures from Business Processes

在线全文

学校读者我要写书评

暂无评论

journal of Computer Science & Technology 2021年第1期36卷 158-190页

作者： yain-Whar Si weng-Hong yung Department of Computer and Information Science University of MacaoMacaoChina

Iterative control structures allow the repeated execution of tasks,activities or sub-processes according to the given conditions in a process *** control structures can significantly increase the risk of triggering temporal exceptions since activities within the scope of these control structures could be repeatedly executed until a predefined condition is *** this paper,we propose two approaches to unravel iterative control structures from process *** first approach unravels loops based on zero-one *** second approach unravels loops based on branching probabilities assigned at split *** proposed methods can be used to unfold structured loops,nested loops and crossing *** the unfolded model does not contain any iterative control structures,it can be used for further analysis by process designers during the modeling *** proposed methods are implemented based on workflow graphs,and therefore they are compatible with modeling languages such as Business Process Modelling Notation(BPMN).In the experiments,the execution behavior of unfolded process models is compared against the original models based on the concept of *** results reveal that runs generated from the original models can be correctly executed in the unfolded BPMN models that do not contain any loops.

关键词： business process management iterative control structure unravelling zero-one principle branching probability

Microstructure of ZM6 magnesium alloy with different Nd content

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2013年第3期32卷 234-240页

作者： weng-yong Shi yan Ma College of Mechanical and Electrical Engineering Northeast Forestry University Harbin 150040 China Graduate School Harbin University of Science and TechnologyHarbin 150080 China

With the purpose of studying the influence of Nd on the alloy structure and castability of ZM6, under the fixed content of Zn and Zr, this paper observes and analyzes the microstructure morphology of ZM6 alloy fracture with dif- ferent Nd content by the means of uniaxial tension experiment and scanning electron microscope （SEM） observation. The search results indicate that the structure of ZM6 alloy after added Nd can be refined to some extent, while it has no obvious influence on the grain structure and dimension of as- ast ZM6 alloy. Through increasing the ratio between Nd and Zn, it turns out that Nd and Zn reduces their own solid solu- bility by each other in α-Mg, and meanwhile, they gather toward the grain boundary, which is beneficial to refine the structure of ZM6 alloy ingot and enables the grain dimension of ZM6 alloy to reach the minimum when the Nd content is 2.5 %. On the basis of the minimization of the grain dimen- sion, the tensile property of ZM6 alloy improves with the Nd content. Thus, it provides theoretical guidance and technical support for the improvement of ZM6 alloy structure.

关键词： ZM6 alloy Magnesium alloy Microstructure

Electrochemical synthesis of ammonia in molten salts

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

journal of Energy Chemistry 2020年第4期29卷 195-207页

作者： jiarong yang Wei weng Wei Xiao School of Resource and Environmental Sciences Hubei International Scientific and Technological Cooperation Base of Sustainable Resource and EnergyWuhan UniversityWuhan 430072HubeiChina

Ammonia is important feedstock for both fertilizer production and carbon-free liquid *** techniques for ammonia formation have been developed,hoping to replace the industrial energy-intensive Haber-Bosch *** synthesis of ammonia in molten salts is one promising alternative method due to the strong solubility of N3- ions,a wide potential window of molten salt electrolytes and tunable electrode ***,electrochemical synthesis of ammonia in molten salts begins with the electro-cleavage of N2/hydrogen sources on electrode surfaces,followed by diffusion of N3^-/H^+-containing ions towards each other for NH3 ***,the hydrogen sources and molten salt composition will greatly affect the reactions on electrodes and ions diffusion in electrolytes,being critical factors determining the faradaic efficiency and formation rate for ammonia *** report summarizes the selection criteria for hydrogen sources,the reaction characteristics in various molten salt systems,and the preliminary explorations on the scaling-up synthesis of ammonia in molten *** formation rate and faradaic efficiency for ammonia synthesis are discussed in detail based on different hydrogen sources,various molten salt systems,changed electrolysis conditions as well as diverse *** synthesis of ammonia might be further enhanced by optimizing the molten salt composition,using electrocatalysts with well-defined composition and microstructure,and innovation of novel reaction mechanism.

关键词： Electrochemical ammonia synthesis Molten salt electrolysis N2 reduction Hydrogen source

Tourmaline activated persulfate for degradation of Sirius Türkis GL 01

在线全文

学校读者我要写书评

暂无评论

Acta Geochimica 2017年第3期36卷 400-404页

作者： Chih-Huang weng Department of Civil and Ecological Engineering I-Shou University Kaohsiung City 84008 Taiwan

The high Fe^(2+)content of tourmaline(TM)has potential of activating a persulfate ***,information pertaining to using TM as an activator in persulfate oxidation process is currently *** this study,powdered TM was used to activate persulfate(PS)oxidation for decolorization synthetic direct azo dye,Sirius Türkis GL 01(STGL).Findings revealed that decolorization was significantly enhanced by TM/PS combined with ultrasound.A suitable oxidation condition for removal true color was TM 1.5 g/L,PS 5 *10^(-4)M,US 106 W/cm^2(20 min sonication at 20 kHz),and initial pH 6.0,which could completely remove the color and COD of 40 mg/L STGL after 20 min *** condition under higher TM dosage with higher sonication power is beneficial for generation of sulfate radicals,consequently,promoting the oxidation performance of TM/PS *** clearly indicated that Fe-tourmaline,can be potentially used to activate PS oxidation for effective decolorization of wastewater containing direct azo dyes.

关键词： Tourmaline Persulfate oxidation Direct azo dye Ultrasound Decolorization

Structures that should be Described in Higher-Symmetry, Centrosymmetric Space Groups. Part 1. The Disordered Structures of [(CH_3CH_2)_4N]_3{[(SCH_2CH_2S)MoS_3]_2Fe}, [(CH_3CH_2)_4N]_2{[S_2CN(C_2H_5)_2]_4Fe_4S_4} and [(CH_3CH_2)_4N]_3{[(SCH_2C

在线全文

学校读者我要写书评

暂无评论

Chinese journal of Structural Chemistry 2000年第6期19卷 405-410页

作者： weng NgSeik Hu Shengzhi University of Malaya 50 6 0 3 厦门大学福建厦门 36 1 0 0 5

The space groups of [(CH3CH2)4N]3 {[(SCH2CH2S)MoS3]2Fe} and [(CH3CH2)4N]2 {[S2CN(C2H5)2]4Fe 4S4} are revised from Cc to C2/c by solving the C2/c structure from the structure factors that are calculated from the Cc structure. The structures are both disordered in one of the tetraethylammonium cations. The space group of [(CH3CH2)4N]3 {[(SCH2CH2S)MoS3]2Fe} · 1/4CH3CN is revised from Pc to P21/c;because of the severe disorder in the cations that was not addressed in the original refinements, only the atomic coordinates of the metal-cluster anions could be revised. The space group of [(CH3CH2)4N]3 {[(CH3)2NCS2Cu]2MoS4} · 2CH3CN (originally described in P1̄) is re-assigned to C2/c. The general descriptions of the structures are unchanged in the higher-symmetry settings. The revised coordinates are given.

关键词： SCH2CH2S)MoS3 CH3CH2 C2H5 S2CN Structures of Fe

同方期刊数据库

Applications of AMSR-E Measurements for Tropical Cyclone Predictions PartⅠ: Retrieval of Sea Surface Temperature and Wind Speed

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2008年第2期25卷 227-245页

作者： Banghua yAN Fuzhong weng NOAA joint Center for Satellite Data Assimilation Camp Springs MD USA NOAA/NESDIS/Center for Satellite Applications and Research Camp Springs MD USA

Existing satellite microwave algorithms for retrieving Sea Surface Temperature （SST） and Wind （SSW） are applicable primarily for non-raining cloudy conditions. With the launch of the Earth Observing System （EOS） Aqua satellite in 2002, the Advanced Microwave Scanning Radiometer （AMSRoE） onboard provides some unique measurements at lower frequencies which are sensitive to ocean surface parameters under adverse weather conditions. In this study, a new algorithm is developed to derive SST and SSW for hurricane predictions such as hurricane vortex analysis from the AMSRoE measurements at 6.925 and 10.65 GHz. In the algorithm, the effects of precipitation emission and scattering on the measurements are properly taken into account. The algorithm performances are evaluated with buoy measurements and aircraft dropsonde data. It is found that the root mean square （RMS） errors for SST and SSW are about 1.8 K and 1.9 m s^- 1, respectively, when the results are compared with the buoy data over open oceans under precipitating clouds （e.g., its liquid water path is larger than 0.5 mm）, while they are 1.1 K for SST and 2.0 m s^-1 for SSW, respectively, when the retrievals are validated against the dropsonde measurements over warm oceans. These results indicate that our newly developed algorithm can provide some critical surface information for tropical cycle predictions. Currently, this newly developed algorithm has been implemented into the hybrid variational scheme for the hurricane vortex analysis to provide predictions of SST and SSW fields.

关键词： Ocean surface temperature ocean surface wind AMSR-E hurricane vortex analysis