黄河小浪底工程移民安置环境影响评价

本文阐述了小浪底移民安置影响区的基本情况,着重就移民安置对土地资源、生物资源、水资源、公共卫生以及移民安置对移民在经济、生活、文化等方面的影响进行了分析评价,提出了发展对策。     

当前高校大学生考试作弊原因浅析及对策

高校学生考试作弊现象时有发生。其原因包括自我要求降低，教考制度、学生管理等方面存在问题。要改善这种现状，必须促使学生端正学习态度，通过教育改革提高学生学习热情，加强校风校纪建设，完善考试制度，最终杜绝高校学生考试作弊现象。     

NUMERICAL STUDY OF HYDRODYNAMICS OF MULTIPLE TANDEM JETS IN CROSS FLOW

The hydrodynamics of a single jet and four tandem jets in a cross flow are simulated by using the Computational Fluid Dynamics (CFD) software Fluent. The realizable model is used to close the Reynolds-Averaged equations. The flow characteristics of the jets, including the jet trajectory, the velocity field and the turbulent kinetic energy are obtained with various jet-to-cross flow velocity ratios in the range of 2.38-17.88. It is shown that a single jet penetrates slightly deeper than the first jet in a jet group at the same , although the difference decreases with the decrease of . It is also found that the way in which the velo-city decays along the centerline of the jet is similar for both a single jet and the first jet in a group, and the speed of the decay increases with the decrease of . The downstream jets in a group are found to behave differently due to the sheltering effect of the first jet in the group. Compared with the first jet, the downstream jets penetrate deeper into the cross flow, and the velocity decays more slowly. The circulation zone between the two upstream jets in the front is stronger than those formed between the downstream jets. The Turbulent Kinetic Energy (TKE) sees a distinct double-peak across the cross-sections close to each nozzle, with low values in the jet core and high values in the shear layers. The double-peak gradually vanishes, as the shear layers of the jet merge further away from the nozzle, where the TKE assumes peaks at the jet centerline.     

EXPERIMENTAL STUDY ON SEDIMENT RESUSPENSION IN TAIHU LAKE UNDER DIFFERENT HYDRODYNAMIC DISTURBANCES

Contaminants resuspension in sediments induced by wind-wave could influence the water quality in shallow lakes. Resuspension of surface sediments from the Zhushan Bay, Taihu Lake was simulated under different wind forcing by using a pneumatic annular flume in this study. Acoustic Doppler Velocimeter (ADV) was used to measure flow velocity at each wind speed, and the characteristics of sediment resuspension were studied with the layered sampling technology. The experimental results show that the flow velocity increases with wind speed obviously and 6m/s is a critical wind speed which affected hydrodynamic conditions significantly. The distribution of flow velocity and water depth is different from that in ordinary open channel. With the enhanced hydrodynamic factors, the Suspended Solids Concentration (SSC) in water increases accordingly, and the incipient velocity of sediment resuspension is about 0.21 m/s. Based on the analysis of wind speed and average SSC in water column, the quantitative relationship is obtained. The SSC of the bottom layer is higher than the content of surface layer under different hydrodynamic conditions, and there are similar distributions between SSC and flow velocity in different water layers.     

THE EFFECT OF OIL CAVITY DEPTH ON TEMPERATURE FIELD IN HEAVY HYDROSTATIC THRUST BEARING

For a heavy hydrostatic bearing with a high linear velocity,the results of numerical calculations often differ from practical conditions if the viscosity is considered as constant.In this article,the influence of the oil cavity depth on the temperature field in the heavy hydrostatic bearing is discussed in the context of variable viscosity.The viscosity-temperature relations for the gap oil film are first established by fitting B-Spline curves,then,numerical calculations for the temperature field in the heavy hydrostatic bearing of different oil cavity depths are carried out based on Finite Volume Method (FVM) under the same rotating speed,and the influence of the oil cavity depth on the temperature distribution in the gap oil film of the hydrostatic bearing is discussed.The results of numerical calculations provide the temperature distribution state inside the hydrostatic bearing,which would help the selection and the design of hydrostatic bearings in engineering practice.     

FACTORS INFLUENCING BENDING RIGIDITY OF SUBMERGED VEGETATION

The bending rigidity of submerged vegetation is closely related with vegetative drag force. This work aims at determining the effects of flow conditions and characteristics of vegetation on the bending rigidity of submerged vegetation. Based on the dimensional analysis method, the factors influencing the bending rigidity of individual submerged vegetation were analyzed. The relationship between the relative bending rigidity and its influencing factors was investigated by experimental observation, and a rela...     

EFFECTS OF ENTRAINED AIR MANNER ON CAVITATION DAMAGE

Early in 1953 the experiments by Peterka proved that air entrainment has effects on decreasing cavitation damage.This technology has been widely used in the release works of high dams since the inception of air entrainment in the Grand Goulee Dam in 1960.Behavior,mechanism and application of air entrainment for cavitation damage control have been investigated for over half century.However,severe cavitation damage happened due to complex mechanism of air entrainment.The effects of air entrainment are related...     

水工钢衬复合填充接触灌浆技术在景洪水电站的应用

景洪水电站在钢衬接触灌浆施工中,应用了水泥与化学灌浆相结合的复合填充灌浆方法,取得了较好的效果.主要对该技术的实施要点及效果进行介绍,供同类工程借鉴和探讨.     

Urbanization: the challenge for the next century

This article summarizes a new 1996-97 report from the World Resources Institute, the UN Environmental Program, the UN Development Program, and the World Bank, which describes a future with increased levels of urbanization that were reshaping the physical and social environment. Urbanization increased economic growth and environmental degradation. By the year 2000, 50% of the world population will live in urban areas. Cities are the center of economic activity. Consumption is the highest in cities. Cities produce the most pollution and waste. Three issues are particularly crucial to survival: the water supply, sanitation, and water resource management. Neglect of these and other environmental issues is likely to have important consequences in both developing and developed countries. The greatest growth in urban areas is occurring in developing countries. Cities in developing countries have huge populations living in poverty. The poor in either rural or urban areas are confronted with lack of access to clean water, to sanitation, and to housing. There is overcrowding and exposure to industrial wastes and air pollution. There is a need for policy reform, stronger institutions, and enlightened political leadership. Cities need to improve their environment and to strengthen local government and implement poverty reduction programs. Reform of urban policies must be accompanied by effective urban governance. Community-based approaches are essential. Broad-based support is needed for changes in strategies and practices and for attainment of a more sustainable environment.     

China''''s Cooperative Exploration of Oil and Gas and Its Taxation System

China' s foreign-oriented oil taxation system has, from the beginning, been based upon the positive experiences of other oil-producing countries and has incorporated common international practices. The system has been perfected over decades. It of fers more incentives than other oil-producing countries in the following four aspects: (1) Income tax has a "wide tax base and low tax rate"; (2) VAT levies a low tax rate on ma-