Control Measures of Soil Erosion in a Typical Construction Project Area ( Dina 2 Gas Field)

To treat the relationship between project construction and ecological environment and effectively prevent new soil erosion during the construction, according to the project layout, soil erosion distribution as well as natural and socio-economic conditions, the control measures of newly increased soil erosion along the project were carried out based on site survey and analysis of relevant information. In addition, adhering to the prin- ciple of partition prevention and treatment, some guiding prevention and control measures of the natural zone passed by the project and soil erosion control district were determined, which provided scientific references and technical support for the rational layout of water and soil conservation and ecological restoration measures in Dina 2 gas field.

A new method of calculating crown projection area and its comparative accuracy with conventional calculations for asymmetric tree crowns

This paper introduces a new method of calculating crown projection area(CPA),the area of level ground covered by a vertical projection of a tree crown from measured crown radii through numerical interpolation and integration.This novel method and other four existing methods of calculating CPA were compared using detailed crown radius measurements from 30 tall trees of Eucalyptus pilularis variable in crown size,shape,and asymmetry.The four existing methods included the polygonal approach and three ways of calculating CPA as the area of a circle using the arithmetic,geometric and quadratic mean radius.Comparisons were made across a sequence of eight non-consecutive numbers(from 2 to 16)of measured crown radii for each tree over the range of crown asymmetry of the 30 trees through generalized linear models and multiple comparisons of means.The sequence covered the range of the number of crown radii measured for calculating the CPA of a tree in the literature.A crown asymmetry index within the unit interval was calculated for each tree to serve as a normative measure.With a slight overestimation of 2.2%on average and an overall mean error size of 7.9%across the numbers of crown radii that were compared,our new method was the least biased and most accurate.Calculating CPA as a circle using the quadratic mean crown radius was the second best,which had an average overestimation of 4.5%and overall mean error size of 8.8%.These two methods remained by and large unbiased as crown asymmetry increased,while the other three methods showed larger bias of underestimation.For the conventional method of using the arithmetic mean crown radius to calculate CPA as a circle,bias correction factors were developed as a function of crown asymmetry index to delineate the increasing magnitude of bias associated with greater degrees of crown asymmetry.This study reveals and demonstrates such relationships between the accuracy of CPA calculations and crown asymmetry and will help increase awareness among researchers and practitioners on the existence of bias in their CPA calculations and for the need to use an unbiased method in the future.Our new method is recommended for calculating CPA where at least four crown radius measurements per tree are available because that is the minimum number required for its use.

HOLDITCH THEOREM FOR THE CLOSED SPACE CURVES IN LORENTZIAN 3-SPACE

In this article, we give the area formula of the closed projection curve of a closed space curve in Lorentzian 3-space L3. For the 1-parameter closed Lorentzian space motion in L3, we obtain a Holditch Theorem taking into account the Lorentzian matrix multiplication for the closed space curves by using their othogonal projections onto the Euclidean plane in the fixed Lorentzian space. Moreover, we generalize this Holditch Theorem for noncollinear three fixed points of the moving Lorentzian space and any other fixed point on the plane which is determined by these three fixed points.

Structure and Flow Characteristics of Flat Fan Nozzles with a Single Orifice Formed by a Rectangular Cut

The flat fan nozzle with a single orifice formed by a rectangular cut at the nozzle exit through a semi-ellipsoid blind end was developed. The flow rate characteristic of the nozzle was analyzed. Theoretical analysis shows that the discharge coefficient of the nozzle is a function of the ratio of the projected exit flow area to the cross sectional area of the nozzle input section. Water spraying experiment results show that the discharge coefficient increases with the increase of the ratio of the projected exit flow area to the cross sectional area of the nozzle input section when the rectangular cut depth doesn't exceed the distance from the center of the hemisphere to the nozzle end; conversely,the discharge coefficient decreases with the increase of the ratio; for a given nozzle,the discharge coefficient varies with Reynolds number.

The Drivers of Land Use Change in the Migration Area, Three Gorges Project, China: Advances and Prospects

This paper reviewed existing literatures on land use change since the demonstration phase of the Three Gorges Project and found that reservoir inundation, migration resettlement, urban relocation, and post-supporting construction were first paid more attention to, when analyzing the driving forces of land use change in the migration area. However, at the post-migration period （the end of migration resettlement）, above-mentioned drivers had not obviously driven land use change, but the evolutions of ＂migration demands＂ replacing them increasingly became the major drivers of land use change in the migration area. Therefore, the future priority fields of land use explanations in the mi- gration area, Three Gorges Project were （1） identifying the corresponding relationships between the spatial distributions of land use change and migration resettlement and indigenous inhabitants; （2） un- derstanding the change of ＂migration demands＂ and their causing ＂indigenous inhabitants＇ demands＂ being how to drive land use transforms; （3） finding the driving processes of the conflict and exclusion between immigrants and indigenous inhabitants, and the transfer of immigrants and indigenous in- habitants on land use change; and （4） measuring the dynamic feedback of ＂migration demands＂ at dif- ferent stages on the processes, directions and their corresponding impacts of land use change in order to building the coupling framework among ＂migration demands＂, driver behaviors, and land use. This paper presents a new access for the explanation of land use change and also supplies scientific proofs to obtain adaptive decision-making to optimize land use patterns in the migration area, Three Gorges Project.

Global Trade Center,A New Landmark Project in Anzhen Area

The overall planning of Beijing Global Trade Center (GTC) is being carried out by the U.S. designing firm EDAW and the first-phase office building has already been put into use, while the second and third phases are under construction. Guided by the modernity, hi-tech design, a human-oriented approach, and the integration of land-