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411.
随着通信产业的蓬勃发展,双频段无线通信系统对双频段滤波器的要求愈来愈高。实现滤波器的带宽和中心频率可控且保持良好的阻带特性一直是难以解决的问题。该文提出了一种采用枝节加载双模开环谐振器设计的微带双模双频段滤波器。该双模双频段滤波器是通过两个工作在不同频段的单频段双模滤波器并联而成的,因此滤波器两个频段的带宽和中心频率是独立可控的。在滤波器的设计中,采用延长耦合馈线的方法实现了过耦合,进而达到了抑制寄生通带的效果。最后,设计了一个工作在2.4/3.5 GHz的应用于无线通信领域的双频段带通滤波器,并对其进行了加工和测量。测量结果和仿真结果的良好吻合验证了设计理论的合理性。 相似文献
412.
413.
为了研究有车家庭居民出行链与出行方式组合的影响关系,将出行链划分为5种类型,并将出行链属性分为4类.利用2009年济南市居民出行调查数据,用基于多项logit模型的基本理论与建模方法,对影响城市居民出行方式组合的因素进行了研究,重点分析了出行链各项属性对居民出行方式选择的影响.模型分析结果表明,出行链中往返行程数量、出行链模式、出行链时间、出行链费用对于出行者选择何种出行方式组合有显著的影响.出行链复杂性的增加并不会直接导致私家车出行的增加,而随着往返行程数的增加会导致单一非私家车出行效用的显著增加. 相似文献
414.
基于通勤班车出行者意向调查与分析,掌握班车出行行为特性,建立了基于ML模型的班车出行前端衔接方式选择模型,确定前端衔接时间.并以满足最大出行需求、线路总体通行时间最短的路径寻优双重目标,建立了班车线路优化模型,并通过启发式算法进行求解.研究结果表明,约占78.1%的班车出行者前端衔接时间占总出行时间的比例在0.2~0.5;85%以上的班车出行者希望(容忍)最早出发时间不早于实际出发时间,通过实例验证可通过通勤班车线路的优化设置来提高公共交通出行. 相似文献
415.
管泽英 《国防交通工程与技术》2011,9(2):60-63,80
钻孔灌注桩的后压浆技术在桥涵和房屋建筑中应用很多,但注浆工艺、注浆参数对岩土的适用性都有待进一步研究.京石客专石家庄隧道的盖挖段施工中由于地质原因灌注桩达不到设计桩长,采用成桩后对支撑桩进行后注浆处理的措施,以提高支撑桩的单桩承载力.介绍了钻孔灌注桩后注浆的作用机理,进行了注浆前与注浆后桩基承载力的对比计算,阐述了具体... 相似文献
416.
417.
文章在分析传统Dijkstra算法的基础上,针对传统Dijkstra算法存在的两点不足之处,引入了一种优化算法。当后勤补给运输的网络规模较大及其关联矩阵为一个稀疏矩阵时,以上优化算法与传统Dijkstra算法相比,能大大减少计算次数及比较次数,提高运算效率。 相似文献
418.
The steering torque of an electric-power steering (EPS) motor is interrelated with the performance of the EPS control system,
therefore calculating an exact steering torque is critical in this application. This study presents a dynamic correction method
that greatly decreases the calculated error in the steering torque; the PID controller demonstrated here is therefore suitable
for the demands of this system. Based on an analysis of the detection process of the steering torque sensor, we first deduced
that the variation of the system resistance torque equals the difference between the measured value of the steering torque
and the ideal one in the previous cycle. Based on this result, we then proposed a dynamic correction method. Finally, a comparison
of the simulated and experimental results for several vehicles evidenced the effectiveness of this dynamic correction method. 相似文献
419.
This paper presents the design optimization process of a short fiber-reinforced plastic armrest frame to minimize its weight
by replacing the steel frame with a plastic frame. The analysis was carried out with the equivalent mechanical model and design
of experiment (DOE) method. Instead of considering the whole structure, it is divided into three simpler regions to reduce
the complexity of the problem through examining its structural characteristics and load conditions. The maximum stress and
deflection of the regions that carry the normal load are calculated by the analytical mathematical form derived from an equivalent
model. The other regions loaded by contact stress are handled by FEM (finite element method), the DOE method, and the RSM
(response surface model). To optimize the design variables in both cases, the object functions derived from these calculations
are solved with a CAE (computer aided engineering) tool. This method clearly shows the mechanical and mathematical representation
of structural optimization and reduces the computing costs. After design optimization, the weight of the optimum plastic-based
armrest frame is reduced by about 18% compared to the initial design of a plastic frame and is decreased by 50% in comparison
with the steel frame. Some prototypical armrest frames were also made by injection molding and tested. The research results
fulfilled all of the design requirements. 相似文献
420.
This paper presents a methodology to optimize the sizing of the energy and power components in a fuel cell electric vehicle from the driving mission (which includes driving cycles, a specified acceleration and autonomy requirements). The fuel cell and the Energy Storage System associated (battery or/and ultra capacitor) design parameters are the numbers of series and parallel branches respectively Nsi and Npi. They are set so as to minimize the objective function that includes mass, cost, fulfilling the performance requirements and respect the technological constraints of each power component through a penalty function. The methodology is based on a judicious combination of Matlab-Simulink® for the global simulation and a dedicated software tool Pro@Design®. Both are well suited to treat inverse problems for the optimization. An application for a fuel cell/battery powertrain illustrates the feasibility of the proposed methodology. 相似文献