Forces Driving Changes in Cultivated Land and Management Countermeasures in the Three Gorges Reservoir Area,China

The Three Gorges project accelerates economic development in the Three Gorges Reservoir Area.This paper aimed to investigate the distribution,changes and features of cultivated land in this area,analyze the forces driving the changes in cultivated land area,and propose the countermeasures for cultivated land management.Transition matrix was used to analyze the features of cultivated land changes,and quantitative analysis and qualitative analysis were adopted to research the driving forces according to the features of cultivated land changes.Cultivated land in the Three Gorges Reservoir Area mainly lay to the northwest of the Yangtze River,especially the upper reaches.The areas of cultivated land increased from 1996 to 1999,then decreased from 2000 to 2006,and finally increased again from 2007 to 2009.The important forces driving changes in cultivated land included government policies,employment and food security,increasing construction land,agriculture structure adjustment,land rearrangement,inundation.During cultivated land management,firstly,it is necessary to insist on the principle of cultivated land protection,standardize land exploitation and strictly restrict the transformation of cultivated land into non-farming land.Secondly,land rearrangement must be implemented,which can not only increase the area of the cultivated land,but also improve the quality of the cultivated land.Thirdly,it is feasible to intensify eco-agriculture construction to increase the quantity and quality of cultivated land.Fourthly,it is helpful to improve the traditional agriculture production methods to promote cultivated land quality.Lastly,it is important to propagandize cultivated land protection and realize the enormous pressure of cultivated land shortage,making more people obligated to protect cultivated land.

Development Trends of Transmissions for Hybrid Electric Vehicles Using an Optimized Energy Management Strategy

Energy conservation and emissions reduction have become increasingly significant for automobiles due to the severity of the current energy situation.Hybrid electric vehicle(HEV)technology is one of the most promising solutions.This study investigated the total efficiency of a HEV powertrain.To improve the total efficiency,the engine should be regulated to work at its highest efficiency and drive the wheels directly as much as possible.To accomplish this,we developed an energy management strategy based on the direct drive area(DDA)of the engine’s efficiency map.Several typical HEV models were built to compare the fuel consumption using DDA and rule-based strategies.Furthermore,the function of the HEV transmission system with DDA was considered.The transmission in a HEV should regulate the engine to work at its highest efficiency as much as possible,which is rather different than the regulation in an internal combustion engine vehicle.The functional change may lead to transmission systems with fewer gears but optimal gear ratios.If this trend is realized,the manufacturing cost of HEVs could be largely reduced.