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。     

基于三相-单相变换器的牵引供电系统及并网控制

为了解决过分相给牵引供电系统带来的问题,研究了三电平三相-单相二极管箝位变换器,把三电平三相-单相变换器用作牵引变电所核心设备,搭建了基于此变换器的贯通式牵引供电系统。分析了三相变换器数学模型,设计了变换器控制系统,研究了单相变换器在贯通式牵引供电系统中的并网控制。利用Matlab／Simulink建立了三变电所贯通式牵引供电系统,仿真验证了该系统架构以及三相-单相变换器的控制性能和并网性能,证明了该系统的可行性。     

轮对多边形化对车辆动力学性能的影响

基于弹性轮对建立车轮多边形的刚柔耦合整车动力学模型。首先分析弹性车轮的合理性,进而通过修改命令直接形成多边形,研究弹性车轮多边形的波深、相位差、谐波阶数在不同速度下对车辆动力学性能的影响,给出40⁸0 km/h下,车轴横向力、轮轨横向力、脱轨系数、轮重减载率等重要指标,确定出危险速度。结果表明,3个参数对动力学性能的影响存在差异,但对脱轨系数影响都很小,对60 km/h速度下的轮重减载率影响都很大,应尽量避免在60 km/h下长期运行,以免发生共振。     

连续梁桥减震性能中阻尼影响的试验研究

阻尼是桥梁的重要动力参数之一 ,研究阻尼在减震中的作用对抗震设计很有指导价值 .通过有机玻璃连续梁桥模型振动台试验 ,分析了阻尼对模型桥梁和墩减震性能的影响 .试验表明 ,阻尼的大小对减震性能有着重要的作用 .适当的增加阻尼会降低振动幅值 ,扰乱振动过程中规则的相位 ,从而得到良好的减震效果     

VFT PHASE VOLTAGE MEASUREMENT IN THREE-PHASE ENCLOSED GIS

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Study on the Formation of η Phase During TIG Welding

The paper studied the effect of Ni-Fe-C filler materials on the η phase formation during TIG welding of WC-30Co and 45 steel. ηphase's morphology and forming condition were discussed using BEI method. The properties of the weld joints were also measured using microhardness measurement and four-point bending measurement. The results show that the weld joints of WC-30Co/45 steel can be obtained by TIG welding using different Ni-Fe-C materials as filler materials, and ηphase formed in the joints is M6C, M12C type carbides. The poor carbon content of the W-Co-C system resulted from the C diffusion and the high ingredient Fe are the two vital factors inducing to ηphase formation. It can be restricted by the addition of C element into Ni-Fe material. When carbon content is 0.01 % in filler material, bend strength σbb of weld joint is 908 MPa. However, when carbon content increases to 0. 41% in filler material, bend strength σbb is 1 260 MPa.     

Statistical Features and Phase Identification of Traffic Flow on Urban Freeway

At present, researches on traffic flow theory mainly focus on highway traffic, which is significantly different from urban freeway. Because traffic science is an “empirical science”, it is based on actual traffic flow data of urban freeway, the statistical features of velocity distribution at different densities have been investigated in this paper. Moreover, four steady phases: free flow, coherent-moving flow, synchronized flow, and jams are identified in the flow rate-density plane of the traffic flow. Finally, features of the four phases as well as functional forms of phase boundaries are discussed in detail.     

浅谈房地产开发设计阶段成本管理

随着我国房地产开发的不断发展,越来越多的房地产商意识到了设计阶段成本管理的重要性.但如何进行设计阶段成本管理,如何改善和提高设计阶段成本管理水平,大多数房地产商还处于摸索阶段.本文通过对一些具体案例的分析,来阐述设计阶段成本管理的一些办法和思路.