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为实现多种类型的柴油机系统快速建模仿真,利用MATLAB/Simulink,根据模块化思想,以功能为划分原则,把柴油机系统分解为一系列独立又相互联系的子系统,分别建立其模型,建立对应的具有相同模块构建规则的子模块,并建立模块库。在此基础上,可以通过调用不同的库模块,实现不同机型的仿真,并且利用模块库技术管理模块库,实现模块库的更新和扩展,动态满足多样化的仿真目的,从而提高模块的通用性,最终实现多种机型快速建模仿真。 相似文献
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丰富的煤炭资源决定了在我国能源消费结构中煤炭将长期占据主导地位;煤炭资源与经济发达程度的逆向分布决定了“西煤东运、北煤南运”运输格局;沿江河产业带的形成、发展、壮大以及环境、能源问题日益严重决定了内河水运必将发挥越来越重要的作用.在对我国煤炭资源禀赋、产消运格局分析的基础上,提出蒙东、贵州煤炭不宜跨区域调运,能源金三角煤炭重点保“铁海联运”,新疆煤炭主要供应华中地区煤炭调运格局,以及以长江干线为骨架、支流为网络,构建“北装南卸”的煤炭运输格局. 相似文献
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本文提出了一种新的电动助力转向系统的控制策略,以减小车辆静止时改变方向所需的转向力。以前尝试通过减少不良的转向振动来减少转向扭矩失败的原因是因为高辅助增益往往会产生震荡或增加噪声敏感性。为了消除此种振动,开发出一种基于控制齿轮角速度的控制策略,它是在简化的转向模型的基础上开发出来的。这个实验获得了很好的齿轮角速度的估计值,这样就有可能消除方向盘所有旋转速度下的振动。实验证明在方向盘大转速变换下,转向扭矩显著降低,无振动传输给司机。所提出的控制策略使用一个辅助来获得超过原来的三倍以上的增益。此外,所提出的控制策略不需要补充传感器。 相似文献
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From the perspective of a transport service buyer and at the abstraction level of material flows, all transports travel directly from product supplier to product customer. In reality, however, the directness of transport services depends on factors such as geography, available infrastructure, temporary conditions, shippers' qualitative preferences, the economy of and practical possibilities for consolidation and access to return flows. This work examines directness by structuring and elaborating upon the causes of freight transport detours and briefly analysing their effect. The article also includes a discussion about the prospects of capturing directness in a KPI, and how such a measure can be designed, measured, monitored and used, as well as a brief analysis of the consequences of using it for monitoring and controlling supply chain performance. 相似文献
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Barbara Schmucki 《Research in Transportation Economics》2012,34(1):74-85
Using photographs, this paper explores the gendered link between transport and the urban environment. It becomes apparent that moving around in urban spaces is an experience which is or can be fundamentally different for women and men. From pictures I conclude that a historical analysis of gender and urban transport ought to be a straightforward task to undertake: women are clearly visible in the visual record of the transport environment. However, a look at the historiography shows that research on gendering the city mostly deals with workplaces, women’s employment, class and race segregation in urban areas, welfare programmes specially designed to helped women, urban housing and marginalisation of women, housewives, healthcare, homeless women and politics. Gender and transport is hardly to be found: how women move and moved through urban space has not received sustained attention. Further, the main body of scholarly texts lacks in historical concern, stemming from such diverse disciplines as sociology, geography, economic and political sciences, women’s studies and planning. 相似文献
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Impact of phytoplankton community size on a linked global ocean optical and ecosystem model 总被引:1,自引:0,他引:1
We isolated the effect phytoplankton cell size has on varying remote sensing reflectance spectra (Rrs(λ)) in the presence of optically active constituents by using optical and radiative transfer models linked in an offline diagnostic calculation to a global biogeochemical/ecosystem/circulation model with explicit phytoplankton size classes. Two case studies were carried out, each with several scenarios to isolate the effects of chlorophyll concentration, phytoplankton cell size, and size-varying phytoplankton absorption on Rrs(λ). The goal of the study was to determine the relative contribution of phytoplankton cell size and chlorophyll to overall Rrs(λ) and to understand where a standard band ratio algorithm (OC4) may under/overestimate chlorophyll due to Rrs(λ) being significantly affected by phytoplankton size. Phytoplankton cell size was found to contribute secondarily to Rrs(λ) variability and to amplify or dampen the seasonal cycle in Rrs(λ), driven by chlorophyll. Size and chlorophyll were found to change in phase at low to mid-latitudes, but were anti-correlated or poorly correlated at high latitudes. Phytoplankton size effects increased model calculated Rrs(443) in the subtropical ocean during local spring through early fall months in both hemispheres and decreased Rrs(443) in the Northern Hemisphere high latitude regions during local summer to fall months. This study attempts to tease apart when/where variability about the OC4 relationship may be associated with cell size variability. The OC4 algorithm may underestimate [Chl] when the fraction of microplankton is elevated, which occurs in the model simulations during local spring/summer months at high latitudes in both hemispheres. 相似文献