葛洲坝大江电厂采用500kV刀闸拉环流总结

总结了大江电厂首次采用500kV刀闸拉环流隔离故障断路器的操作情况和相应措施。

Pseudo-Fluid Simulation of Transient Behaviors in a CFB Riser

The kinetic theory of granular flow (KTGF) is modified to fit the Einstein′s equation for effective viscosity of dilute flow. A pseudo-fluid approach based on this modified KTGF is used to simulate the dynamic formation and dissipation of clusters in a circulating fluidized bed riser. The agglomeration of particles reduces slip velocity within particle clusters, and hence results in two reverse trends: discrete particles are lifted by air while particle clusters fall down along the wall. The dynamic equilibrium of these two types of motion leads to the characteristic sigmoid profile of solid concentration along the longitudinal direction. The predicted solid velocity, lateral and longitudinal profiles of solid volume fraction and annulus thickness are in reasonable agreement with experimental results.

Climate Change Impacts on Water Resources of Greater Zab River, Iraq

Greater Zab is the largest tributary of the Tigris River in lraq where the catchment area is currently being plagued by water scarcity and pollution problems. Contemporary studies have revealed that blue and green waters of the basin have been manifesting increasing variability contributing to more severe droughts and floods apparently due to climate change. In order to gain greater appreciation of the impacts of climate change on water resources in the study area in near and distant future, SWAT （Soil and Water Assessment Tool） has been used. The model is first tested for its suitability in capturing the basin characteristics, and then, forecasts from six GCMs （general circulation models） with about half-a-century lead time to 2046-2064 and one-century lead time to 2080-2100 are incorporated to evaluate the impacts of climate change on water resources under three emission scenarios： A 1 B, A2 and BI. The results showed worsening water resources regime into the future.

Calculation of stratosphere–troposphere exchange in East Asia cut-off lows:cases from the Lagrangian perspective

In this study,the authors focus on the cut-off low pressure systems（COLs）lingering over East Asia in late spring and early summer and quantify the two-way stratosphere–troposphere exchange（STE）by 3D trajectory integrations,achieved using a revised version of the UK Universities Global Atmospheric Modelling Programme Offline Trajectory Code（Version 3）.By selecting 10 typical COLs and calculating the cross-tropopause air mass fluxes,it is found that stratosphere-to-troposphere transport（STT）fluxes exist in the center of COLs;and in the periphery of the COL center,troposphereto-stratosphere transport（TST）fluxes and STT fluxes are distributed alternately.Net transport fluxes in COLs are from stratosphere to troposphere,and the magnitude is about 10-4 kg m-2 s-1.The ratio between the area-averaged STT and TST fluxes increases with increasing strength of the COLs.By adopting appropriate residence time,the spurious transports are effectively excluded.Finally,the authors compare the results with previous studies,and find that the cross-tropopause fluxes（CTFs）induced by COLs are about one to two orders of magnitude larger than global CTFs.COLs play a significant role in local,rapid air mass exchanges,although they may only be responsible for a fraction of the total STE.

Hydrological Response to Environment Change in Himalayan Watersheds: Assessment from Integrated Modeling Approach

Land use changes such as deforestation,increase in cropping or grazing areas and built-up land, likely modify the water balance and land surface behavior in the Himalayan watersheds.An integrated approach of hydrological and hydraulic modeling was adopted for comparative analysis of hydrological pattern in three Himalayan watersheds i.e.Khanpur,Rawal and Simly situated in the Northern territory of Pakistan.The rainfall-runoff model SWAT- Soil and water assessment tool and Hydro CAD were calibrated for the selected watersheds.The correlation analysis of the precipitation data of two climate stations i.e.Murree and Islamabad, with the discharge data of three rivers was utilized to select best suitable input precipitation data for Hydro CAD rainfall-runoff modeling.The peak flood hydrograph were generated using Hydro CAD runoff to optimize the basin parameters like CN, runoff volume, peak flows of the three watersheds.The hydrological response of the Rawal watershed was studied as a case study to different scenarios of land use change using SWAT model.The scenario of high deforestation indicated a decline of about 6.3% in the groundwater recharge tostream while increase of 7.1% in the surface runoff has been observed under the scenario of growth in urbanization in the recent decades.The integrated modeling approach proved helpful in investigating the hydrological behavior under changing environment at watershed level in the Himalayan region.

Analyzing the influences of two types of El Nino on Tropical Cyclone Genesis with a modified genesis potential index

To understand the impacts of large-scale circulation during the evolution of E1 Nifio cycle on tropical cyclones （TC） is important and useful for TC forecast. Based on best-track data from the Joint Typhoon Warning Center and reanalysis data from National Centers for Environmental Prediction for the period 1975- 2014, we investigated the influences of two types of E1 Nifio, the eastern Pacific E1 Nifio （EP-E1 Nifio） and central Pacific E1 Nifio （CP-E1 Nifio）, on global TC genesis. We also examined how various environmental factors contribute to these influences using a modified genesis potential index （MGPI）. The composites reproduced for two types of E1 Nifio, from their developing to decaying phases, were able to qualitatively replicate observed cyclogenesis in several basins except for the Arabian Sea. Certain factors of MGPI with more influence than others in various regions are identified. Over the western North Pacific, five variables were all important in the two E1Nifio types during developing summer （July-August-September） and fall （October- November-December）, and decaying spring （April-May-June） and summer. In the eastern Pacific, vertical shear and relative vorticity are the crucial factors for the two types of El Nifio during developing and decaying summers. In the Atlantic, vertical shear, potential intensity and relative humidity are important for the opposite variation of EP- and CP-EI Nifios during decaying summers. In the Southern Hemisphere, the five variables have varying contributions to TC genesis variation during peak season （January-February-March） for the two types of E1 Nifio. In the Bay of Bengal, relative vorticity, humidity and omega may be responsible for clearly reduced TC genesis during developing fall for the two types and slightly suppressed TC cyclogenesis during EP-E1 Nifio decaying spring. In the Arabian Sea, the EP-E1 Nifio generates a slightly positive anomaly of TC genesis during developing falls and decaying springs, but the MGPI failed to capture this variation.

On the existence and stability of 2-D perturbed steady subsonic circulatory flows

In this paper, under the generalized conservation condition of mass flux in a unbounded domain, we are concerned with the global existence and stability of a perturbed subsonic circulatory flow for the two-dimensional steady Euler equation, which is assumed to be isentropic and irrotational. Such a problem can be reduced into a second order quasi-linear elliptic equation on the stream function in an exterior domain with a Dirichlet boundary value condition on the circular body and a stability condition at infinity. The key ingredient is establishing delicate weighted Hlder estimates to obtain the infinite behaviors of the flow under physical assumption.

LOOP GROUP ACTIONS AND THE RIBAUCOUR TRANSFORMATIONS FOR FLAT LAGRANGIAN SUBMANIFOLDS

The Ribaucour transformations for flat Lagrangian submanifolds in Cn and CPn via loop group actions are given. As a consequence, the authors obtain a family of new flat Lagrangian submanifolds from a given one via a purely algebraic algorithm. At the same time, it is shown that such Ribaucour transformation always comes with a permutability formula.