Direct Computation of the Performance Index for an Optimally Controlled Active Suspension with Preview Applied to a Half-Car Model

A quadratic integral performance index is defined for a linear active preview-type suspension and a series of matrix expressions derived for its evaluation by means of MATLAB or some similar computer program in the case of a unit step input to the system. The computation, which is both fast and accurate compared to simulation, requires the solution of Lyapunov- and Riccati-type equations. Some examples of numerical computation are given and these show excellent agreement with published results. The conclusion features a useful computer program.     

新能源车--世界第一辆混合动车

东日本铁路公司已经把环境保护列为其"集团远景规划"之一,并正在积极地为保护环境而努力.在这方面,减少列车运行所需能量是一个重大的课题,目前正在致力于实现重大改进.然而,由于再生制动不能配置在内燃动车上,因而其能量效率要比电动车低. 东日本铁路公司研发中心一直致力于开发一种新能源车,其目标是通过革新驱动系统,减少铁路动车运行时对环境的影响.作为第一步,已经建造了世界上第一台有混合动力系统的试验车,一种使用锂离子蓄电池储能的批量生产的混合系统已经装车.自2003年5月以来一直在进行试验.该混合系统就其性能和能量效率来说,几乎达到了预想的运行水平.     

The Gothenburg traffic restraint scheme

Officials at various levels around the world are getting increasingly worried about the growth in automobile ownership and all the associated environmental problems that this implies. Voices are often heard advocating the exclusion of automobiles from the central areas of cities, much easier to say than to realise, unless the area is entirely reconstructed under a comprehensive redevelopment scheme, as, for instance, in the city of Västeras, Sweden. Another possible solution is to introduce some type of traffic restraint scheme involving compulsory rearrangement of the vehicular flow through the central area.The report deals firstly with an experiment carried out during the highly intensive, pre-Christmas shopping days in December 1969, when parts of the central business area of the city of Gothenburg, Sweden (population around 450,000) were closed to all unauthorised vehicles. The experience gained with this scheme was valuable when the next stage was being planned, i.e., a permanent traffic restraint scheme which was put into effect on August 18, 1970. Most of the report deals with the objectives, planning, realisation, and experience of the traffic restraint scheme, which involved dividing the central business area into five separate zones. During the first six months, several surveys were conducted to establish the impact of the scheme on vehicular flow, parking, pedestrian flow, public transport, accidents, air pollution, noise, and retail businesses.The scheme put into operation in Gothenburg has been a great success, having accomplished most of its objectives, and will be expanded to cover a still larger area in subsequent years.This paper is an amended and updated version of one originally prepared in May 1971 for the Environment Directorate of the Organisation for Economic Cooperation and Development, whose permission to publish is gratefully acknowledged.     

A methodology for vehicle sideslip angle identification: comparison with experimental data

Sideslip angle could provide important information concerning vehicle's stability. Unfortunately direct measurement of sideslip angle requires a complex and expensive experimental set-up, which is not suitable for implementation on ordinary passenger cars; thus, this quantity has to be estimated starting from the measurements of vehicle lateral/longitudinal acceleration, speed, yaw rate and steer angle. According to the proposed methodology, sideslip angle is estimated as a weighted mean of the results provided by a kinematic formulation and those obtained through a state observer based on vehicle single-track model. Kinematical formula is considered reliable for a transient manoeuvre, while the state observer is used in nearly quasi-state condition. The basic idea of the work is to make use of the information provided by the kinematic formulation during a transient manoeuvre to update the single-track model parameters (tires cornering stiffnesses). A fuzzy-logic procedure was implemented to identify steady state or transient conditions.     

Filling up gaps in wave data with genetic programming

A given time series of significant wave heights invariably contains smaller or larger gaps or missing values due to a variety of reasons ranging from instrument failures to loss of recorders following human interference. In-filling of missing information is widely reported and well documented for variables like rainfall and river flow, but not for the wave height observations made by rider buoys. This paper attempts to tackle this problem through one of the latest soft computing tools, namely, genetic programming (GP). The missing information in hourly significant wave height observations at one of the data buoy stations maintained by the US National Data Buoy Center is filled up by developing GP models through spatial correlations. The gap lengths of different orders are artificially created and filled up by appropriate GP programs. The results are also compared with those derived using artificial neural networks (ANN). In general, it is found that the in-filling done by GP rivals that by ANN and many times becomes more satisfactory, especially when the gap lengths are smaller. Although the accuracy involved reduces as the amount of gap increases, the missing values for a long duration of a month or so can be filled up with a maximum average error up to 0.21 m in the high seas.     

Heat exchanger/catalytic system for reducing the exhaust emissions from diesel engines

A system has been researched over the past 3 years for reducing the exhaust pollutants from diesel engines for light commercial vehicles. The system researched achieves Euro 6 standards for reduction of polluting gases (CO, HC, PM, NO). It consists of 4 main sections: 1. A heater and heat exchanger (HE); 2. A CO/HC oxidising catalyst (D°C); 3. Pt catalyst on a diesel particulate filter (DPF); 4. A NO reducing reaction (SCR) within the DPF. The system operates as follows. The exhaust gas contains oxidising gases, namely both O₂ and NO₂. The levels of CO and HC are oxidised by O₂ to CO₂ for temperatures above 200°C. Carbon (PM) is oxidised to CO₂ by NO₂ but requires a temperature above 250°C. The operating exhaust temperature of 300°C is ideal for the removal of NO by using the Pt catalyst and the CO generated within the DPF. The heater is required to be able to raise the exhaust temperature at any time to 300°C in order to optimise the performance of the system, since diesel engine exhaust temperatures vary between 160°C (slow speeds) to 350°C (high speeds). Considerable heat is required (??3 kW) to maintain the exhaust gas for a 2l engine at 300°C for engine idle conditions. Therefore a heat exchanger is required to re-circulate the input heat and thereby reduce the maximum power consumption to a maximum of 500W over the engine full operating test cycle. This energy is supplied by the engine battery and alternator. Experimental results have been obtained for the exhaust from a Kubota diesel engine and the reductions in exhaust emissions of 83% (CO/ HC), 58% (NOx) and 99% (PM) were obtained. The PM was continuously cleaned so that there was no build up of back pressure.     

Maglev Vehicle/Guideway Vertical Random Response and Ride Quality

Summary The research and development (R & D) of maglev technology had made a great progress in China since the early 1980s. Especially, a 35 km-long Shanghai high-speed maglev railway employing the German Transrapid system began to be constructed on March 1, 2001. Based on the Transrapid system, the paper develops a 10-degree-of-freedom model of maglev vehicle running over three types of guideways with constant speed. Random guideway irregularities are discussed and taken into account for simulation of the vehicle response and for evaluation of the ride comfort. Using the direct time integration method and the discrete fast Fourier transform (DFFT), random responses of the maglev vehicle-guideway systems are obtained and analyzed. Numerical results show that the resonant frequency of car body acceleration response is 0.5-1 Hz, and there is a 2.2 Hz periodic vibration due to the periodic configuration of rigid piers when the maglev vehicle travels over the elevated-beam guideway. The car body acceleration power spectral density (PSD) curves meet well the ride quality criterion of the urban tracked aircushion vehicle (UTACV) and the maximum acceleration of car body is less than 0.05 g. Moreover, the Sperling ride index values are less than 2.5 as long as the operational speed is less than 450 km/h. It is concluded that the maglev vehicle ride quality is quite well.     

Phytoplanktonic nutrient utilisation and nutrient signature in the Southern Ocean

The separation in Southern Ocean provinces of silicate excess at nitrate exhaustion and of nitrate excess at silicate exhaustion was already introduced by Kamykowski and Zentara (Kamykowski, D., Zentara, S.J., 1985. Nitrate and silicic acid in the world ocean: patterns and processes. Mar. Ecol. Prog. Ser. 26, 47–59; and Kamykowski, D., Zentara, S.J., 1989. Circumpolar plant nutrient covariation in the Southern Ocean: patterns and processes. Mar. Ecol. Prog. Ser. 58, 101–111) and our investigations of the silicate to nitrate uptake ratios confirm the earlier distinction. Oligotrophic antarctic waters mainly exhibit proportionally higher silicate removal what induces a potential for nitrate excess. The nitrogen uptake regime of such areas is characterised by low absolute as well as specific nitrate uptake rates throughout. Maximal values did not exceed 0.15 μM d⁻¹ and 0.005 h⁻¹, respectively. Corresponding f-ratios ranged from 0.39 to 0.86. This scenario contrasts strikingly to the more fertile ice edge areas. They showed a drastic but short vernal increase in nitrate uptake. Absolute uptake rates reached a maximum value of 2.18 μM d⁻¹ whereas the maximal specific uptake rate was 0.063 h⁻¹. In addition to an optimal physical environment for bloom development, accumulation of ammonium stimulated nitrate uptake in a direct or indirect way. Since ammonium build-up in surface waters traces enhanced remineralisation, release of other essential compounds during degradation of organic matter might have been the main trigger. This peak nitrate utilisation during early spring led to the observed potential for silicate excess. With increasing seasonal maturity the nitrate uptake became inhibited by the presence of enhanced ammonium availability (up to 8% of the inorganic nitrogen pool), however, and after a short period of intensive nitrate consumption the uptake rates drop to very low levels, which are comparable to the ones observed in the area of nitrate excess at silicate exhaustion.     

PACDIN statement of methods

PAntograph–Catenary Dynamic Interaction (PACDIN) is a code developed by the vehicle technology research centre (CITV) of the Universitat Politècnica de València in collaboration with the railway company Talgo S.L. The model of the catenary is a finite element model using absolute nodal coordinates. It is based on a general formulation that can be applied for analysing a wide range of catenary configurations, including stitch wire, transitions or non-straight path tracks. The formulation is fully non-linear and includes large deformations, dropper slackening and contact interaction. The model is linearised when deformations are small, as in the case of the benchmark dynamic analysis. The results of the PACDIN code show a good agreement with the average results of other benchmark codes.