基于FPGA的MVB1类设备网卡的设计

考虑到MVB1类设备网卡支持简单的过程数据传送(功能代码为0～4)和设备状态响应(功能代码15)，不支持消息数据、过程数据强制功能的情况，提出利用FPGA(现场可编程门阵列)开发MVB1类设备网卡。这样，在完成通信功能的同时，可以无需外加CPU即完成一些简单的IO、AD等功能，也可以设计出总线方式与CPU相连。实践证明MVB1类设备网卡采用PC104接口与宿主CPU连接，具有110个256位的过程数据通信能力；用FPGA开发MVB1类设备网卡比用MVBC芯片更具优势。     

Preparing highway emissions inventories for urban scale modeling: A case study in Philadelphia

Highway emissions represent a major source of many pollutants. Use of local data to model these emissions can have a large impact on the magnitude and distribution of emissions predicted and can significantly improve the accuracy of local scale air quality modeling assessments. This paper provides a comparison of top–down and bottom–up approaches for developing emission inventories for modeling in one urban area, Philadelphia, in calendar year 1999. A bottom–up approach relies on combining motor vehicle emission factors and vehicle activity data from a travel demand model estimated at the road link level to generate hourly emissions data. This approach can result in better estimates of levels and spatial distribution of on-road motor vehicle emissions than a top–down approach that relies on more aggregated information and default modeling inputs.     

Offshore export versus in situ fractionated mineralization: a 1-D model of the fate of the primary production of the Rías Baixas (Galicia, NW Spain)

A linked hydrodynamic mineralization model is described and used to evaluate offshelf fluxes and fractionated mineralization of particulate phytogenic materials in the coastal upwelling system of the Rías Baixas (NW Spain), under three different typical situations of the upwelling season. The simulations made indicate that the intensity of upwelling controls: (a) net community production (NCP); (b) particulate organic matter (POM) accumulation; (c) in situ mineralization; and (d) matter export in the ‘Rías Baixas.’ Under strong upwelling conditions, there is an important horizontal offshelf flux, having only a small mineralization effect on NCP; if weak upwelling conditions are simulated, POM export is dramatically reduced and in situ mineralization is significantly enhanced; finally, under average upwelling conditions, the offshelf export of POM is about one third of the POM accumulation inside the domain, evidencing its importance in the productivity enhancement of near-shore areas. According to our sensitivity tests, the net vertical velocity (water velocity plus sinking velocity) has a critical role in the C/N/P stoichiometry of POM.     

Structural stability of polymer matrix composite panels in fire

Development in advanced composite fabrication technology offers the clear prospect of cost effective application of polymer matrix composites for large load-bearing structures. However, polymer matrix composites can be severely degradated under the thermal condition caused by fire. This paper addresses the compressive load-bearing capacity for polymer matrix composite panels in naval structures and civil infrastructures under the combined thermal–mechanical condition. The failure modes arising from structural instability for single skin and sandwich panels in such combined thermal–mechanical condition are the focus in this study. The thermal field under fire heating and the degradation of mechanical properties with elevated temperature are discussed. Analytical solutions for these mechanical failure modes are presented for design considerations. The approach to the development of a quantitative methodology for fire protection design is discussed in the context of the analyses and the experiments. Design diagrams are constructed to design mechanical loads for given fire protection time, and on the opposite, to design fire protection time for given mechanical loads.     

中集集装箱半挂车进入日本市场

人们看惯了日本汽车在中国满地跑,谁见过中国人造的车在日本的国土上跑?可是现在,深圳中集专用车有限公司就让他们制造的集装箱半挂车成功进入了日本市场。 2006年4月5日,日本某专用车制造公司执行董事西川先生专程来到深圳,与中集专用车公司洽谈进一步扩大合作的事宜。     

Radar Health Monitoring for Highway Vehicle Applications

Monitoring the health of the radar sensor on a highway vehicle poses a special challenge. This is because the radar measures the distance to other independent vehicles on the highway and the motion of these other vehicles may be completely unknown to the fault detection system. Traditional observer-based approaches to fault diagnostic system design cannot be used. A number of new approaches are therefore explored in this paper in an attempt to create a reliable fault detection system for the radar. These include: (a) Use of inter-vehicle communication; (b) Use of a geographic database of pre-identified roadside radar targets; (c) Detection of abrupt failures using fuzzy logic and a knowledge of vehicle acceleration abilities; (d) Use of a redundant sensor that is inexpensive but of poor quality. The performance of each of these approaches is evaluated. Experimental results indicate that a combination of approaches (c) and (d) would provide the most reliable method for radar health monitoring. This combination would work effectively even in the absence of inter-vehicle communication in a realistic highway environment.     

降低感应电机直接转矩控制的转矩脉动的控制器

基于磁滞比较器和选择表的感应电机直接转矩控制(DTC),其开关频率可变,且转矩脉动大,特别在低速时.这是因为转矩和磁通的变化率以及转矩和磁通达到其上带和下带所花的时间随运行工况变化.文中提出了一种新型的开关频率固定的转矩控制器.新型控制器结构非常简单,其输出类似于传统的三点式磁滞比较器.就提出的控制器介绍了近似频域分析法,作为控制器参数选择的指南.介绍了感应电机直接转矩控制采用该转矩控制器进行的仿真和实验结果.结果表明提出的控制器可以保持开关频率恒定,并降低了转矩脉动,尤其在低速时.     

Construction of a stochastic model of track geometry irregularities and validation through experimental measurements of dynamic loading

This paper describes the construction of a stochastic model of urban railway track geometry irregularities, based on experimental data. The considered irregularities are track gauge, superelevation, horizontal and vertical curvatures. They are modelled as random fields whose statistical properties are extracted from a large set of on-track measurements of the geometry of an urban railway network. About 300–1000 terms are used in the Karhunen–Loève/Polynomial Chaos expansions to represent the random fields with appropriate accuracy. The construction of the random fields is then validated by comparing on-track measurements of the contact forces and numerical dynamics simulations for different operational conditions (train velocity and car load) and horizontal layouts (alignment, curve). The dynamics simulations are performed both with and without randomly generated geometrical irregularities for the track. The power spectrum densities obtained from the dynamics simulations with the model of geometrical irregularities compare extremely well with those obtained from the experimental contact forces. Without irregularities, the spectrum is 10–50?dB too low.     

Customer loads of two-wheeled vehicles

Customer usage profiles are the most unknown influences in vehicle design targets and they play an important role in durability analysis. This publication presents a customer load acquisition system for two-wheeled vehicles that utilises the vehicle's onboard signals. A road slope estimator was developed to reveal the unknown slope resistance force with the help of a linear Kalman filter. Furthermore, an automated mass estimator was developed to consider the correct vehicle loading. The mass estimation is performed by an extended Kalman filter. Finally, a model-based wheel force calculation was derived, which is based on the superposition of forces calculated from measured onboard signals. The calculated wheel forces were validated by measurements with wheel–load transducers through the comparison of rainflow matrices. The calculated wheel forces correspond with the measured wheel forces in terms of both quality and quantity. The proposed methods can be used to gather field data for improved vehicle design loads.     

Donor states and donee states: investigating geographic redistribution of the US federal-aid highway program 1974–2008

In 2009, the US government spent more than $42 billion on the federal-aid highway program. Most of this money was raised from motor vehicle taxes, whose proceeds are deposited in the highway trust fund. Federal motor vehicle user taxes flow into the fund and aid expenditures flow out from it to build and maintain highways and other transportation infrastructure. With so much money at stake it should be no surprise that expenditure decisions are the subject of intense political debate. Chief among these debates is the conflict between donor states, whose residents pay more in highway user taxes than the state receives in federal highway aid and donee states, whose residents pay less in highway user taxes than the state receives in highway aid. While this geographic redistribution has been masked recently by infusions of general fund revenue into the trust fund, the debate nevertheless continues. This paper attempts to understand why some states are donors and others are donees by simultaneously testing four hypotheses about the geographic redistribution of federal highway dollars that relate to a state’s highway need, economic condition, level of urbanization, and representation on the key Congressional oversight committees. The analyses show that redistribution does not favor states with larger highway systems, more highway use, or lower median incomes, all of which are different indicators of need. Instead, states that are less urban and better represented on the four key Congressional committees generally benefit from redistribution. These findings indicate that the user tax revenues are not used in places where they are most needed. Thus they provide little empirical support for any compelling policy argument for continued geographic redistribution of federal highway user tax dollars.