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991.
介绍了76000DWT巴拿马型散货船的总体性能开发设计情况.同时介绍了计算流体动力学(CFD)多方案分析比较的线型设计、燃油保护给散货船设计带来的新要求并提出了相应的解决方案. 相似文献
992.
In the past fifteen years, the attention of ship safety treatment as an objective rather than a constraint has started to sweep through the whole maritime industry. The risk-based ship design (RBD) methodology, advocating systematic integration of risk assessment within the conventional design process has started to takeoff. Despite this wide recognition and increasing popularity, important factors that could potentially undermine the quality of the results come from both quantitative and qualitative aspects during the risk assessment process. This paper details a promising solution by developing a formalized methodology for risk assessment through effective storing and processing of historical data combined with data generated through first-principle approaches. This method should help to generate appropriate risk models in the selected platform (Bayesian networks) which can be employed for decision making at design stage. 相似文献
993.
随着电动汽车(electric?vehicles,EVs)技术的快速发展,EVs数量激增,将其接入微电网中参与充放电调度成为了降低大规模EVs对电网负面影响的有效途径.?为此,将EVs接入交直流混合微电网的直流侧,考虑EVs的源荷双重特性,针对微电网系统中微源出力及负荷的不确定性,搭建了计及EVs充放电的交直流混合微电... 相似文献
994.
稀疏表示的本质就是稀疏正规化约束下的信号分解。提出一种改进的正交匹配追踪算法,使运算量较高的矩阵求逆运算转变为轻量级的向量运算或向量与矩阵的运算,可以加快逆矩阵和大矩阵乘积的求解。将此算法应用于稀疏表示的人脸识别,探讨并验证了稀疏阀值的设置和训练字典的选择对人脸识别率和识别速度的影响。 相似文献
995.
目前对路面抗滑性能预测多采用经验回归的方式,摩擦力学与路面磨耗之间的力学关系尚未明确,导致路面抗滑性能预测模型的推广应用存在一定的局限性.文中基于能量等价损耗的概念,通过单一轮胎对路面损伤程度的实测,运用能量等价损耗原理可以推算出不同类型的车辆对路面的损耗程度的量化指标. 相似文献
996.
The horizontal vibration of towed seismic streamers is a main reason for efficiency reduction of the seismic survey and tail
tangling. A vibration suppression scheme of towed seismic streamers is investigated in this paper. The towed seismic streamer
is divided into two spans, a controlled span, i.e., the low tension span, and an uncontrolled span, i.e., the high tension
span, by a bird. The system model includes a hyperbolic partial differential equation with variable coefficient describing
the towed seismic streamers, and an ordinary differential equation describing the dynamic of bird. Robust based-model knowledge
and adaptive controllers, based on the Lyapunov method, are designed to isolate the vibration of towed seismic streamers caused
by the course deviations of towing vessel, the variations of towing vessel velocity and the variations of towed seismic streamer
density. The robust based-model knowledge and adaptive controllers exponentially and asymptotically drive the span-towed seismic
streamer displacement to zero, respectively. A finite difference scheme is used to validate the efficiency of the control
law. The proposed controller can isolate effectively the disturbance originated from the towed vessel, and can provide the
improved damping but not sacrifice the isolation performance. The adaptive scheme can tolerate the lack of knowledge of some
uncertain parameters and can directly execute the online adjustment of the parameters. Meanwhile, the proposed control law
is robust and can resist the model uncertainty due to parameter incertitude, model error and unknown disturbance and so on.
The control law only includes velocity and slope, while it does not need the displacement which is difficult to measure in
the practical operations. Thus it is easy to implement. 相似文献
997.
Based on the research results of these years, this paper proposes a design of 3MW direct-driven wind generation inverter,
and takes much effort in the control algorithm research and MATLAB simulation. Some wonderful results are obtained. All this
may provide the reference for practical application. The fuzzy controllers are designed, based on fuzzy logic control theory,
which can perfect control of wind generation system with no mathematic model. Models of permanent magnet synchronous generator
(PMSG) and dual pulse width modulation (PWM) converter with their controllers are set by MATLAB/Simulink. In addition, experiments
are made on the simulation platform of variable speed constant frequency (VSCF) wind power generation system. The behavior
of dual PWM converter is demonstrated by simulations and experiment, and the control strategy is valid and correct. 相似文献
998.
This paper presents a comparative study of evolutionary algorithms which are considered to be effective in solving the multilevel
lot-sizing problem in material requirement planning (MRP) systems. Three evolutionary algorithms (simulated annealing (SA),
particle swarm optimization (PSO) and genetic algorithm (GA)) are provided. For evaluating the performances of algorithms,
the distribution of total cost (objective function) and the average computational time are compared. As a result, both GA
and PSO have better cost performances with lower average total costs and smaller standard deviations. When the scale of the
multilevel lot-sizing problem becomes larger, PSO is of a shorter computational time. 相似文献
999.
为解决机非混行造成的交通低效问题,构建单向平面分流路网,即以机动车干路单向交通组织为基础,以机动车支路和自行车、公交专用路双向交通组织为辅助的公交专用、机非分离的路网模式。首先,采用VISUM,VISSIM模型,对单向平面分流路网与传统混合路网的路网特性、交通运输效率进行分析,结果表明,分流路网在交通绕行、转向比例方面与传统混合路网基本一致。其次,在对两套路网体系进行优化设计的基础上,通过仿真分析,得出单向平面分流路网的运输效率远高于传统混合路网。最后指出,将干路单向化处理,发挥单向道路的横向可穿越特性,辅以减少干路绕行的支路体系,是单向平面分流路网实现高效运行的关键。 相似文献
1000.
Transportation specialists, urban planners, and public health officials have been steadfast in encouraging active modes of
transportation over the past decades. Conventional thinking, however, suggests that providing infrastructure for cycling and
walking in the form of off-street trails is critically important. An outstanding question in the literature is how one’s travel
is affected by the use of such facilities and specifically, the role of distance to the trail in using such facilities. This
research describes a highly detailed analysis of use along an off-street facility in Minneapolis, Minnesota, USA. The core
questions addressed in this investigation aim to understand relationships between: (1) the propensity of using the trail based
on distance from the trip origin and destination, and (2) how far out of their way trail users travel for the benefit of using
the trail and explanatory factors for doing so. The data used in the analysis for this research was collected as a human intercept
survey along a section of an off-street facility. The analysis demonstrates that a cogent distance decay pattern exists and
that the decay function varies by trip purpose. Furthermore, we find that bicyclists travel, on average, 67% longer in order
to include the trail facility on their route. The paper concludes by explaining how the distance decay and shortest path versus
taken path analysis can aid in the planning and analysis of new trail systems.
Kevin J. Krizek is an Associate Professor of Planning and Design at the University of Colorado where he directs the Active Communities/Transportation Research Group. His research interests include land use-transportation policies and programs that influence household residential location decisions and travel behavior. He has published in the areas of transportation demand management, travel behavior, neighborhood accessibility, and sustainable development. He earned a Ph.D. in Urban Design and Planning and M.S.C.E. from the University of Washington in Seattle. His master’s degree in planning is from the University of North Carolina at Chapel Hill and his undergraduate degree is from Northwestern University. Ahmed El-Geneidy is a Post-Doctoral research fellow at the Department of Civil Engineering, University of Minnesota and Humphrey Institute of Public Affairs. El-Geneidy’s research interests include transit operations, travel behavior, land use and transportation planning, and accessibility/mobility measures in urban areas. He earned B.S. and M.S. degrees from the Department of Architectural Engineering at the University of Alexandria, Egypt, and continued his academic work at Portland State University, where he received a Graduate GIS Certificate and earned a Ph.D. in Urban Studies from Nohad A. Toulan School of Urban Studies and Planning. Kristin Thompson was a research assistant with ACT and currently works for Metro Transit in Minneapolis, Minnesota. 相似文献
Ahmed El-GeneidyEmail: |
Kevin J. Krizek is an Associate Professor of Planning and Design at the University of Colorado where he directs the Active Communities/Transportation Research Group. His research interests include land use-transportation policies and programs that influence household residential location decisions and travel behavior. He has published in the areas of transportation demand management, travel behavior, neighborhood accessibility, and sustainable development. He earned a Ph.D. in Urban Design and Planning and M.S.C.E. from the University of Washington in Seattle. His master’s degree in planning is from the University of North Carolina at Chapel Hill and his undergraduate degree is from Northwestern University. Ahmed El-Geneidy is a Post-Doctoral research fellow at the Department of Civil Engineering, University of Minnesota and Humphrey Institute of Public Affairs. El-Geneidy’s research interests include transit operations, travel behavior, land use and transportation planning, and accessibility/mobility measures in urban areas. He earned B.S. and M.S. degrees from the Department of Architectural Engineering at the University of Alexandria, Egypt, and continued his academic work at Portland State University, where he received a Graduate GIS Certificate and earned a Ph.D. in Urban Studies from Nohad A. Toulan School of Urban Studies and Planning. Kristin Thompson was a research assistant with ACT and currently works for Metro Transit in Minneapolis, Minnesota. 相似文献