负序继电器在船舶上的应用与分析

将负序继电器用在船舶上,以防止接岸电时,相序接错和单相运行是非常有效的一种方法。本文剖析其的主要构成及其实质负序电压过滤器,绘出了船舶接岸电时的实用接线图,并通过矢量图对其负序原理、断相原理等进行了分析,列出了有关的分析方程,进一步证明了其在船舶上的继电保护原理。     

基于双核DSP的科氏质量流量计并行信号处理

科里奥利质量流量计可直接测量介质质量流量与密度,因而被广泛应用于海洋石油领域。针对单处理器难以保证CMF信号处理实时性要求的问题,基于双核DSP设计了多任务分布的CMF并行信号处理方法。完成数据采集与数字滤波计算任务的预处理进程与完成频率检测与相位差检测任务的后处理进程以并行方式分布在双核DSP中,2个进程之间通过核间中断进行同步。为了验证相位差检测实时性与精度,构建了CMF信号处理验证平台。实验结果表明,基于双核DSP的CMF并行信号处理方法具有更高的精度与实时性。     

考虑相变作用的冻土路基应力与变形分析模型

基于冻土路基温度场的控制方程,考虑水分转化为冰的相变作用对土体瞬时变形和蠕变变形的影响,建立路基应力和变形的二维数值方程,并通过1月份的路基冻胀力学模型,分析冻胀带内水分相变引起的路基应力和变形的分布规律.研究发现,在冻胀区域一定的情况下,冻胀率的大小决定了路基表面应力和变形的极值大小;竖向位移的最大值在坡脚处产生,并向路基中部和左侧边界逐渐递减;随着冻胀率的增加,路基表面裂缝有从坡脚向路中发展的趋势;路基表面产生最大拉应力的位置与最大竖向位移的位置基本吻合;路中所承受的拉应力主要发生在水分集聚的相变带范围内.结果表明,相变作用是引起路基发生冻胀病害的直接因素,分析路基应力与变形的分布规律是研究多年冻土路基破坏机理的有效方法.     

船舶电站新型数字同步表的设计

针对船舶电站准同步并车的要求以及特点,设计高精度新型数字同步表。以Proteus和Keil为实验平台,完成了相应的软件编程和外围硬件电路的设计,分析了主要技术环节的实现。仿真实验结果表明新型数字同步表的设计完全实现了针对待并发电机和电网电压的频差和相位差的检测与显示功能,且运行可靠,检测精度高,成本低。     

The importance of the use phase on the LCA of environmentally friendly solutions for asphalt road pavements

In order to assess sustainability of products and processes, different methodologies have been developed and used in the last years. In the road pavement construction area, most methodologies used for Life Cycle Assessment (LCA) are essentially focused in the construction phase. The present paper analyses the importance of the use phase of a road in the LCA of different paving alternatives, namely by evaluating energy consumption and gaseous emissions throughout the road pavement’s life. Therefore, a new LCA methodology for road pavements was developed, and the results of its application to a case study involving the construction of alternative pavement structures are discussed. The study intends to assess the influence of using more sustainable paving construction alternatives (asphalt recycling vs. conventional asphalt mixtures), and/or different surface course materials (which have a higher influence on the rolling resistance and, therefore, affect the performance during the use phase). The LCA results obtained for this case study showed that the reductions in energy consumption and gaseous emissions obtained during the use phase, for pavement alternatives with a lower rolling resistance surface course, are higher than the total amount of energy consumption and gas emissions produced during construction. It is therefore clear that some improvements in the characteristics of the surface course may have an effect over the road use phase that will rapidly balance the initial costs and gas emissions of those interventions. The LCA results obtained also showed that the sustainability of pavement construction may also be improved using recycled asphalt mixtures.     

Analysis of energy consumption of food transit in an urban agglomeration in Poland

The paper presents the results of research on operational energy consumption of a vehicle in conditions of urban transit in Poland. An important role in Intelligent Transportation Systems in the road transport is played by transit in urban agglomerations. The analysis was based on the use of telemetry systems and statistical analysis of the waveform of digital speed recording. The resulting empirical cumulative distribution functions of phases of acceleration and deceleration speeds allowed to determine the kinetic losses of the vehicle (fuel consumption). The statistical significance of differences between cumulative distribution functions was tested using the Smirnov–Kolmogorov test.     

An object-oriented method for fully coupled analysis of floating offshore wind turbines through mapping of aerodynamic coefficients

This work presents a novel object-oriented approach to model the fully-coupled dynamic response of floating offshore wind turbines (FOWTs). The key features offered by the method are the following: 1) its structure naturally allows for easy implementation of arbitrary platform geometries and platform/rotor configurations, 2) the analysis time is significantly faster than that of standard codes and results are accurate in situations where rotor dynamic contribution is negligible, and 3) an extremely flexible modeling environment is offered by the object-oriented nature of Modelica. Moreover, the current modeling facility used for the code development is open source and is naturally suitable for code sharing. In the present method, the aerodynamic model computes the aerodynamic loads through the mapping of steady-state aerodynamic coefficients. This modeling approach can be placed at the intersection between simplified aerodynamic methods, such as TDHMill, and full beam element/momentum-based aerodynamic methods. Aerodynamic loads obtained from the coefficients mapping are composed of a concentrated thrust and a concentrated torque. The thrust acts at the hub, while the torque is applied at the rotor low-speed shaft of a simplified rigid rotor equation of motion (EoM) used to emulate the rotor response. The aerodynamic coefficients are computed in FAST for a baseline 5 MW wind turbine. A standard rotor-collective blade-pitch control model is implemented. The system is assumed to be rigid. Linear hydrodynamics is employed to compute hydrodynamic loads. The industry-standard numerical-panel code Sesam-Wadam (DNV-GL) is used to preprocess the frequency-domain hydrodynamic problem. Validation of the code considers a standard spar-buoy platform, based on the Offshore Code Comparison Collaboration (OC3-Hywind). The dynamic response is tested in terms of free-decay response, Response Amplitude Operator (RAO), and the time histories and power spectral densities (PSDs) of several load cases including irregular waves and turbulent wind. The resulting model is benchmarked against well-known code-to-code comparisons and a good agreement is obtained.     

表贴式永磁同步电机对称稳态运行仿真研究

表贴式永磁电机阻抗小对输入电压十分敏感,为此需要得到足够准确的电压值才能进行电压源激励下的仿真研究。传统相量图需要较准确的电机模型及参数才能获得端口电压。为此,本文提出一种基于端口等效电路的相量图的有限元稳态仿真方法。该方法仅需计算定子电阻和端部漏感参数,然后采用电流源激励二分法获取较准确的输入电压,并通过时域有限元进行仿真验证。     

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针对城市交叉口交通流的特点,提出了一种自适应可变相序的多相位控制算法。该算法依据绿灯相位车队长度和红灯相位车队长度的比较决定绿灯相位是否转移,在不需要绿灯相位转移时,利用模糊神经网络控制器控制绿灯延时长度。不但结合了模糊控制和神经网络控制的优点,而且所给出的算法相序可变,实现了道路交叉口多相位相序可变控制。仿真结果表明,本文设计的模糊神经网络控制器能够有效降低车辆平均延误,满足实时控制的要求。     

横向磁通电机各相独立控制策略研究

本文分析了横向磁通各相异性的特点,提出了不同于传统三相矢量控制的控制方法,即三角函数法各相独立控制。分析了各相独立控制的原理,建立了数学模型,并与传统控制方法进行了对比仿真,仿真结果表明:三角函数法各相独立控制能很好的平衡各相电流,控制策略优于传统方法。