The principle of energy-saving in hydraulic hybrid vehicles was introduced. The characteristics of hybrid vehicles with electric or hydraulic were compared. Because of its higher power density and higher efficiency, hydraulic hybrid vehicle is more advantageous when working under the condition changed frequently such as city bus. Different arrangement forms of the hydraulic hybrid system were analyzed to explore their own characteristics and applications. Based on the batteries with high energy density and hydraulic accumulators with high power density, a kind of combination that include their respective advantage were proposed. Keywords-Hydraulic hybrid vehicle; Energysaving ; power density; arrangement form; Status and development trend I. 2005 EPA Eaton UPS(United Parcel Service) 60 70 CO 40 [1] II.A.

The electromagnetic information visualization is an indispensable part of the virtual battlefield environment, the radar information becomes more important, especially for radar detection range visualization. In this paper, three dimensional visualization of the design and implementation of radar detection range has been researched. Based on visualization program of radar electromagnetic wave propagation attenuation, this paper presents a computational model of radar electromagnetic wave propagation attenuation in complex atmospheric environment and the rendering algorithm based on spatial sampling. Applying software programming and visualization techniques, simulating the actual terrain and combining with radar data parameters, the paper realizes three-dimensional visualization of the radar detection range under the complex atmospheric environment. Keywords-radar detection range; three-dimensional visualization; propagation attenuation; rendering algorithm; atmospheric environment l.INTRODUCTlONNowadays, for a better understanding and applying of radar, the research field of radar electromagnetic information visualization has been very keen. Traditional research methods are mainly based on numerical parameters characteristics and mapping of the two-dimensional power diagram to analyze and display. Applying radar equation, Ref [I] does numerical analysis for multi-radar's four approaches and describes the inspection method of multi radar detection range in detail. Based on numerical analysis, Ref [2] has researched radar detection capability and warning time. U.S. Navy laboratory STGMAPLOT procedures [3] plotted the radar power in the fonn of two dimensional curve. However, these methods are obviously insufficient, it is also difficult to meet the demand for radar detection information visualization. Gradually, people began to pay attention to the three-dimensional representations of the radar information. As early as in 1999, Cheng Bolin [4] proposed the program of using MA TLAB to draw the radar 3D scope, it realizes a simpler three-dimensional effect. Based on computer graphics and applying radar range fonnula to calculate the coordinates of the point on the lobe of the radar antenna, Weimin Ling [5] also realizes three-978-1-4673-5000-6/13/$31.00 ©2013 IEEE 1033 dimensional display of the radar detection range. However, these programs are only simple three-dimensional visualization of radar detection range, the result is simpler, less precise, realistic. Applying U. S. Navy Advanced Propagation Model (APM) [6], Chao Yang [7] realizes the cylinder drawn of radar information dissemination, which has preferable visual effects. However, each time when changing the viewing angle, it needs to recalculate all data. So this method has higher hardware requirements, slower run speed and less efficient.Considering the impact of the natural environment on the perfonnance of the radar propagation and applying radar wave propagation attenuation theory, this paper proposes a computational model of radar attenuation of elec...