船舶主机调速系统的鲁棒PID控制研究

调速系统是船舶主机遥控系统的核心组成部分,目前国内外先进的船舶主机调速系统大多采用了数字式调速器,使主机遥控向“智能化”方向发展．常规的PID控制最主要的问题是参数整定问题,一旦整定完毕,在整个控制过程中将是固定不变的,而在实际系统中,由于过程中会出现状态和参数的不确定,系统很难达到最佳的控制效果,严重的话可能导致系统的不稳定．该文介绍了鲁棒PID控制在船舶主机转速系统中的应用,由仿真结果可知,该控制方法有良好的控制性能和鲁棒性．     

基于DEA的吉林省汽车制造企业生产效率分析

汽车产业是吉林省经济的支柱产业,但吉林省汽车制造企业的生产效率尚有进一步提升的空间。本文以包括吉林省在内的22家汽车制造企业上市公司的数据为样本,运用DEA数据包络分析法对各汽车制造企业上市公司的生产效率进行实证分析。     

基于DEA的铁路货场运营绩效评价的研究

采用数据包络分析方法中的C2R模型对铁路货场进行运营绩效评价,在综合考虑各种投入与产出的基础上,选择评价指标,建立了铁路货场运营绩效评价模型。最后通过实例验证了模型的有效性。     

治理发展模式与城市轨道交通项目运营效率的关系研究

在"集约、智能、绿色、低碳"的新型城镇化道路快速发展的影响下,中国很多城市都在大力发展城市轨道交通(以下简称城轨)系统.至关重要的是,城轨系统涉及其运营效率和治理开发模式,其中,治理开发模式对其运营过程将产生深远影响.本文概述了中国很多城轨项目发展所采用的公司化模式及政府和社会资本合作(PPP)模式.在运营效率分析中考虑了城轨项目运营所产生的社会效益,构建了城轨项目社会效益测算模型.应用数据包络分析(DEA)方法分析城轨各条线路治理发展模式和运营效率之间的关系.通过对北京市城轨各条线路运营效率的比较分析,结果表明,社会效益是评价城轨项目运营效率的一个重要产出指标,相比于在中国占主导地位的公司化模式,PPP模式对提高城轨运营效率有积极影响.     

Robust control of anti-lock brake system

A robust control algorithm for an anti-lock brake system is proposed. The method used is based on static-state feedback of longitudinal slip and does not involve controller scheduling with changing vehicle speed or road adhesion coefficient estimation. An improvement involving scheduling of longitudinal slip reference with longitudinal acceleration measurement is included. Electromechanical braking actuators are used in simulations, and the algorithm used in this study is shown to have high performance on roads with constant and varying adhesion coefficients, displaying nice robustness properties against large vehicle speed and road adhesion coefficient variations. Guidelines are provided for tuning controller gains to cope with unknown actuator delay and measurement noise.     

Multi-period planning of closed-loop supply chain with carbon policies under uncertainty

Climate change and greenhouse gases emissions have caused countries to implement various carbon regulatory mechanisms in some industrial sectors around the globe to curb carbon emissions. One effective method to reduce industry environmental footprint is the use of a closed-loop supply chain (CLSC). The decision concerning the design and planning of an optimal network of the CLSC plays a vital role in determining the total carbon footprint across the supply chain and also the total cost. In this context, this research proposes an optimization model for design and planning a multi-period, multi-product CLSC with carbon footprint consideration under two different uncertainties. The demand and returns uncertainties are considered by means of multiple scenarios and uncertainty of carbon emissions due to supply chain related activities are considered by means of bounded box set and solve using robust optimization approach. The model extends further to investigate the impact of different carbon policies such as including strict carbon cap, carbon tax, carbon cap-and-trade, and carbon offset on the supply chain strategic and operational decisions. The model captures trade-offs that exist among supply chain total cost and carbon emissions. Also, the proposed model optimizes both supply chain total cost and carbon emissions across the supply chain activities. The numerical results reveal some insightful observations with respect to CLSC strategic design decisions and carbon emissions under various carbon policies and at the end we highlighted some managerial insights.     

Data-driven spatio-temporal discretization for pedestrian flow characterization

We propose a novel approach to pedestrian flow characterization. The definitions of density, flow and velocity existing in the literature are extended through a data-driven spatio-temporal discretization framework. The framework is based on three-dimensional Voronoi diagrams. Synthetic data is used to empirically investigate the performance of the approach and to illustrate its advantages. Our approach outperforms the considered approaches from the literature in terms of the robustness with respect to the simulation noise and with respect to the sampling frequency. Additionally, the proposed approach is by design (i) independent from an arbitrarily chosen discretization; (ii) appropriate for the multidirectional composition of pedestrian traffic; (iii) able to reflect the heterogeneity of the pedestrian population; and (iv) applicable to pedestrian trajectories described either analytically or as a sample of points.     

一种用μ分析设计的舵减摇鲁棒控制器

船舶模型不确定性严重影响着舵减摇的效果。本文用μ分析方法设计了一种Ｈ∞控制器来解决结构化模型不确定性的问题。用船舶线性模型和非线性模型模拟海上航行条件的计算仿真表明μ分析控制器具有良好的鲁棒特性。     

基于奇异滤波及稳健回归的轨道曲线主点定位方法研究

曲线主点位置的准确获取是线路整正的基础。在缺失线形标记的情况下如何准确地计算出轨道主点的位置一直是业界广泛关注的问题。在分析曲线轨道正矢图形的特征后,提出基于奇异分解和稳健回归的曲线主点定位方法:利用相对测量正矢数据构造截断矩阵进行奇异值分解滤除其中幅值较大的冲击部分,在此基础上通过稳健回归减少数据微小变化带来的拟合偏差,得到主点的具体位置。实验表明:该方法能够基于相对测量的正矢数据推算出曲线各个主点的位置,受分段点选取偏差影响较小,适合工程应用。     

基于改进DEA法的铁路应急预案编制绩效评价方法研究

针对铁路应急预案编制绩效评价指标体系多输入、多输出等特性,提出选用DEA法对铁路应急预案编制绩效进行综合评价。同时,针对传统DEA法的局限性,提出改进的DEA法,克服传统DEA法无法确定有效决策单元优劣顺序的缺陷,并针对应急预案编制评价指标的重要程度给予不同的权重,提高了评价结果的可靠性和准确性。最后以青藏铁路公司为例对其预案编制绩效进行综合评价,验证该方法的合理性和可靠性。