新能源汽车电池管理方法综述

电池管理系统作为电动汽车的重要组成部分,其中准确估测荷电状态(SOC)和电池均衡管理是电池管理系统的核心功能,也是优化系统能量管理,提高动力电池的使用效率,延长电池使用寿命的关键,对电池的储能至关重要。详细介绍主要SOC的估测方法和电池均衡管理方法,并对其优劣性进行分析与阐述,通过文献综述与对比分析为电池组在使用时提出理论依据与维护措施,为未来的研究提供便捷研究方法。     

电池SOC估算方法的研究现状

如今,锂离子电池已成为新能源产业和SOC的研究重点.在锂离子电池研究中,电池容量估算和计算是其中的重点研究之一.SOC直接关系到锂离子电池使用的效率和安全性,正确的SOC估算和计算方法不仅可以增加锂离子电池工作的安全性,并延长锂离子电池的使用寿命[1].相反而言,不合适的SOC估算和计算方法不仅会加速电池的老化,而且会...     

Sea state estimation based on vessel motion responses: Improved smoothness and robustness using Bézier surface and L1 optimization

Floating structures oscillate in waves, where these wave-induced motions may be critical for various marine operations. An important consideration is thereby given to the sea states at the planning and operating stages for an offshore project. The most important information extracted from a sea state is the directional wave spectrum, indicating wave direction, significant wave height, and wave spectrum peak period. Among several available methods of measuring and estimating the directional wave spectrum, the wave buoy analogy technique based on vessel motion responses is an in situ and almost real-time solution without extra costs of devices. If the forms of the wave spectra are not predefined in the estimation, the method is called a nonparametric approach. Its most remarkable advantage is the flexible form, but the smoothness should be regulated. After the discrete Fourier transform has been applied to the measured vessel motions, smoothing is necessary. However, this process results in disturbed vessel cross-spectra and a lowpass characteristic of the windowing function. This paper presents a nonparametric approach for directional wave spectrum estimation based on vessel motion responses. It introduces novel smoothness constraints using Bézier surface and includes a more robust estimate using L1 optimization. Both techniques are applied to the wave buoy analogy for the first time. Numerical simulations are conducted to verify the proposed algorithm.     

大型船舶钨极氩弧重熔工艺应用

疲劳破坏是船体结构的主要破坏形式之一。改进结构节点的设计和施工工艺,可保证船体结构中受交变载荷作用的构件有足够的疲劳寿命。钨极氩弧(Tungsten Inert Gas, TIG)重熔是改善结构节点焊后疲劳强度的有效方法。与目前船上常用的几种改善疲劳强度的方法进行分析对比,对TIG重熔工艺的重要性进行充分论证,获得实施TIG重熔工艺的技术标准和操作要点。TIG重熔工艺不仅改善结构节点疲劳强度,而且为建造具有较长疲劳寿命的大型船舶找到一个行之有效的方法,可产生良好的经济和社会效益。     

深海超高压环境模拟容器裂纹评定

深海超高压环境模拟容器用于模拟水下压力环境,其容器壁上承受反复载荷,容易产生疲劳裂纹.疲劳裂纹扩展是影响其断裂的主要因素.本文旨在分析半椭圆裂纹在老化的深海超高压环境模拟容器中的扩展行为,评估容器的安全性,因此对材料20MnMoNb钢的裂纹扩展特性进行了试验研究,首先考虑三角形和梯形加载情况,通过比较两组实验结果,考察了其材料对保载时间的敏感性.采用基于统一的裂纹扩展率模型的三维有限元方法进行了疲劳裂纹扩展计算,并通过CT试样的一组数值和实验结果进行了验证,最后建立了不同初始尺寸、展弦比和倾角的裂纹有限元模型,并根据裂纹在容器内壁的容许深度准则,计算了容器的剩余寿命.其分析结果可为深海超高压环境模拟容器可靠性评估提供参考.     

基于EMD的矢量水声器方位估计算法

对经验模态分解算法(EMD算法)进行深入研究,对其基本原理、基本性质以及存在的问题进行分析。为改善EMD算法在方位估计的精度,减少高频噪声、间断干扰的影响,本文采用Hilbert-Huang变换方法来消除模态混叠现象。实验结果表明,本文提出的基于EMD的矢量水声器方位估计算法,能够有效提高方位估计的精度。     

电网畸变条件下的功率变换器并网同步法

本文研究一种在电网畸变条件下的功率变换器并网同步法,该方法为MSOGI-FLL,MSOGI构成的谐波解耦网络可以滤除谐波并检测出基波正负序分量,FLL可以动态跟踪电网频率。本文分析MSOGI-FLL的性能,并与DSOGI-FLL进行对比。最后,利用MATLAB仿真软件对这两种算法进行仿真验证,仿真结果验证MSOGI-FLL的性能。     

A generic data assimilation framework for vehicle trajectory reconstruction on signalized urban arterials using particle filters

With trajectory data, a complete microscopic and macroscopic picture of traffic flow operations can be obtained. However, trajectory data are difficult to observe over large spatiotemporal regions—particularly in urban contexts—due to practical, technical and financial constraints. The next best thing is to estimate plausible trajectories from whatever data are available. This paper presents a generic data assimilation framework to reconstruct such plausible trajectories on signalized urban arterials using microscopic traffic flow models and data from loops (individual vehicle passages and thus vehicle counts); traffic control data; and (sparse) travel time measurements from whatever source available. The key problem we address is that loops suffer from miss- and over-counts, which result in unbounded errors in vehicle accumulations, rendering trajectory reconstruction highly problematic. Our framework solves this problem in two ways. First, we correct the systematic error in vehicle accumulation by fusing the counts with sparsely available travel times. Second, the proposed framework uses particle filtering and an innovative hierarchical resampling scheme, which effectively integrates over the remaining error distribution, resulting in plausible trajectories. The proposed data assimilation framework is tested and validated using simulated data. Experiments and an extensive sensitivity analysis show that the proposed method is robust to errors both in the model and in the measurements, and provides good estimations for vehicle accumulation and vehicle trajectories with moderate sensor quality. The framework does not impose restrictions on the type of microscopic models used and can be naturally extended to include and estimate additional trajectory attributes such as destination and path, given data are available for assimilation.     

Towards a generic benchmarking platform for origin–destination flows estimation/updating algorithms: Design,demonstration and validation

Estimation/updating of Origin–Destination (OD) flows and other traffic state parameters is a classical, widely adopted procedure in transport engineering, both in off-line and in on-line contexts. Notwithstanding numerous approaches proposed in the literature, there is still room for considerable improvements, also leveraging the unprecedented opportunity offered by information and communication technologies and big data. A key issue relates to the unobservability of OD flows in real networks – except from closed highway systems – thus leading to inherent difficulties in measuring performance of OD flows estimation/updating methods and algorithms. Starting from these premises, the paper proposes a common evaluation and benchmarking framework, providing a synthetic test bed, which enables implementation and comparison of OD estimation/updating algorithms and methodologies under “standardized” conditions. The framework, implemented in a platform available to interested parties upon request, has been flexibly designed and allows comparing a variety of approaches under various settings and conditions. Specifically, the structure and the key features of the framework are presented, along with a detailed experimental design for the application of different dynamic OD flow estimation algorithms. By way of example, applications to both off-line/planning and on-line algorithms are presented, together with a demonstration of the extensibility of the presented framework to accommodate additional data sources.     

Validating and improving public transport origin–destination estimation algorithm using smart card fare data

Smart card data are increasingly used for transit network planning, passengers’ behaviour analysis and network demand forecasting. Public transport origin–destination (O–D) estimation is a significant product of processing smart card data. In recent years, various O–D estimation methods using the trip-chaining approach have attracted much attention from both researchers and practitioners. However, the validity of these estimation methods has not been extensively investigated. This is mainly because these datasets usually lack data about passengers’ alighting, as passengers are often required to tap their smart cards only when boarding a public transport service. Thus, this paper has two main objectives. First, the paper reports on the implementation and validation of the existing O–D estimation method using the unique smart card dataset of the South-East Queensland public transport network which includes data on both boarding stops and alighting stops. Second, the paper improves the O–D estimation algorithm and empirically examines these improvements, relying on this unique dataset. The evaluation of the last destination assumption of the trip-chaining method shows a significant negative impact on the matching results of the differences between actual boarding/alighting times and the public transport schedules. The proposed changes to the algorithm improve the average distance between the actual and estimated alighting stops, as this distance is reduced from 806 m using the original algorithm to 530 m after applying the suggested improvements.