Evaluation of low-temperature diesel combustion regimes with n-Heptane fuel in a constant-volume chamber

The concept of Low Temperature Combustion (LTC) has been advancing rapidly because it may reduce emissions of NOx and soot simultaneously. Various LTC regimes that yield specific emissions have been investigated by a great number of experiments. To accelerate the evaluation of the spray combustion characteristics of LTC, to identify the soot formation threshold in LTC, and to implement the LTC concept in real diesel engines, LTC is modeled and simulated. However, since the physics of LTC is rather complex, it has been a challenge to precisely compute LTC regimes by applying the available diesel combustion models and considering all spatial and temporal characteristics as well as local properties of LTC. In this paper, LTC regimes in a constant-volume chamber with n-Heptane fuel were simulated using the ECFM3Z model implemented in a commercial STAR-CD code. The simulations were performed for different ambient gas O₂ concentrations, ambient gas temperatures and injection pressures. The simulation results showed very good agreement with available experimental data, including similar trends in autoignition and flame evolution. In the selected range of ambient temperatures and O₂ concentrations, soot and NOx emissions were simultaneously reduced.     

SMA路面配合比设计及质量控制

通过沥青混合料的组成设计和各种试验数据,确定各种规格矿料与沥青的组成比例.找出混合料的最佳组合,为保证SMA路面的性能对质量控制做以介绍.     

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空间分析及基础技术应用是研究集装箱运输的必要手段.大部分交通运输数据集由不同出处、关联性不强的原始数据组成,因而很难得到其空间分布特点.同时,集装箱路径优化和市场可达性在缓解集装箱运输拥堵方面的作用日益凸显.本文基于可用数据库对美国集装箱运输OD分布进行分析.以美国水陆运输理事会的公共货票数据库数据作为内陆铁路线路优化的原始输入.利用类似河流管理的方法优化集装箱运输路径.从进口集装箱的数据集看,从亚洲或者欧洲出发经由北美港口到达美国的集装箱,大部分经由太平洋海岸到达内陆市场.横渡太平洋贸易的进口集装箱枢纽港主要是洛杉矶、长滩和西雅图.横渡大西洋贸易的进口集装箱枢纽港主要是纽约、新泽西州和萨凡纳乔治亚州.太平洋海岸和密西西比河谷地区包括阿尼阿波利斯、芝加哥、堪萨斯城、孟菲斯、达拉斯和休斯顿的流量很高.从美国中西部至东部的集装箱流多经过纽约、新泽西州和诺福克最后到达芝加哥.对于集装箱运输OD分布的分析可以为高成本和多式联运相关分析提供数据基础.     

Partial range scaling method based washout algorithm for a vehicle driving simulator and its evaluation

Unlike an actual vehicle, a vehicle driving simulator (VDS) has limited kinematics, workspace, and bounded dynamic characteristics making it very difficult to simulate dynamic motions of an actual vehicle. To solve these problems, a washout algorithm was developed. The developed algorithm restricts the workspace of the VDS to within the kinematic limit and makes the person driving the VDS perceive movement of an actual vehicle. However, the classic washout algorithm contains several problems, such as time delay and the generation of a wrong motion signal caused by characteristics of the filters. So the driver feels “simulator sickness,” such as fatigue, nausea, headache and so on because of differences between the sense of movement of the VDS and that of a real vehicle. In this paper, a partial range scaling method based washout algorithm, including a tilt coordination system, is developed to enhance the perception of motion and reduce simulator sickness. It is verified by a simulation, a survey, and a bio signal analysis using an electrocardiogram (ECG).     

Parametric optimization of EQ6110HEV hybrid electric bus based on orthogonal experiment design

Parametric optimization is an important step for any mechanical system design, including the development and design of a hybrid electric bus. To obtain an optimized parameter grouping of the EQ6110HEV hybrid electric bus for best fuel economy, an orthogonal experiment design method is applied to the parameter optimization process of the EQ6110HEV hybrid prolusion system. This paper proposes two orthogonal experiment methods; the basically orthogonal experiment method and the synthetically orthogonal experiment method. By this means, the development time and the testing costs are reduced, and the impact of factors and their optimal levels are obtained by a range analysis of the experiment results. The results show that the fuel economy of the optimized parameter grouping is improved by 4.1 percent for the four-stage urban driving cycle in China and by 8.7 percent for the Wuhan urban driving cycle of public buses in China, in comparison with that of the parameter grouping of the current configuration.     

Simple design approach for improving characteristics of interior permanent magnet synchronous motors for electric air-conditioner systems in HEV

In this paper, a simple design method for improving the performance of an interior permanent magnet synchronous motor (IPMSM), for driving the air-conditioning compressor used in hybrid electric vehicles, is presented. There are many design methods that optimize the IPMSM. Each method deals with a variety of design factors, such as slot opening, pole arc, and rotor shape. However, as the number of design variables increases, a lot of modeling and analysis time is needed in order to improve the characteristics of an IPMSM. This paper demonstrates that the optimization of a double-layer IPMSM, satisfying the given design conditions, is possible with only a flux barrier shape design. Then, response surface methodology is applied as the optimization method, and the validity of the design approach is verified by comparison with test results.     

An Active Pantograph with Shaped Frequency Response Employing Linear Output Feedback Control

In pantographs used for current collection on high speed electric trains it is desirable to minimise the fluctuations in the contact force between the collector head and the catenary. A simple two-mass linear model is employed for the pantograph and the design of the proposed control system is based on the input admittance at low frequencies. Frequency shaping is incorporated in the performance index, and a simple dynamic controller is employed to achieve optimality in an equivalent transformed system, while minimising the number of feedback quantities to be measured. A significant reduction in the average contact force appears possible.     

Mixing in the surface boundary layer of a tropical freshwater reservoir

A combined observational-modeling study was conducted to investigate turbulence mixing, and the relation to surface forcing, in the surface boundary layer (SBL) of a tropical, high-altitude, freshwater reservoir. A suite of vertical profiles of temperature microstructure, collected at three different stations of one-day duration each, provided estimates of dissipation rates of turbulence kinetic energy, , and temperature variance, χ. Numerical simulations of and χ, using state-of-the-art, public domain, two-equation turbulence closure models, compared favorably with the observations and reproduced the dynamics of daytime wind mixing as well as the vertical and temporal turbulence structure during nighttime convective conditions.Two independent estimates of vertical eddy diffusivities in the stably stratified (daytime) SBL, computed from the microstructure measurements, agreed closely, and the near surface heat and buoyancy fluxes, computed from the diffusivities, were similar to those computed independently from surface meteorology. Model generated eddy diffusivities agreed closely with the observed values, except those generated by K profile parameterization (KPP) model simulations. The good agreement provides confidence that nutrient fluxes in the SBL may be accurately computed from the models when forced with regularly measured surface meteorological parameters. The consequences are important for estimation of daily primary productivity rates in the euphotic zone and the ability to predict algal blooms such as those observed in the present reservoir.     

Estimation of the Non-Linear Suspension Tyre Cornering Forces from Experimental Road Test Data

The paper discusses the application to real data of an identification procedure based on an Extended Kalman Filter, for estimating the equivalent non-linear suspension tyre cornering forces of a road vehicle from a single standard manoeuvre. In particular, both the steady-state and the dynamic handling characteristics can be evaluated.