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121.
Torque characteristics analysis for optimal design of a copper-layered eddy current brake system 总被引:1,自引:0,他引:1
An enhanced parametric model for a copper-layered eddy current electric machine (retarder) is introduced in this paper. The
modeled torque characteristics of the copper-layered electromagnetic retarders are based on the results from a detailed electromagnetic
finite element analysis (FEA) of these eddy current machines. The model uses a parameterized double-exponential function to
model the steady state speed-torque characteristics of the retarder. The parameters are adjusted for optimal braking performance
in conjunction with predicted speed-torque characteristics of a copper-layered retarder. A full vehicle model, along with
the proposed retarder speed-torque model has been used to simulate a series braking events. The simulation results show that
the peaks of the retarder speed-torque curves must be designed to occur within a specific range of speeds for optimal braking
performance. 相似文献
122.
123.
F. Soriano M. Moreno-Eguilaz J. Alvarez J. Riera 《International Journal of Automotive Technology》2016,17(5):873-882
In this two-part paper, a topological analysis of powertrains for refuse-collecting vehicles (RCVs) based on the simulation of different architectures (internal combustion engine, hybrid electric, and hybrid hydraulic) on real routes is proposed. In this first part, a characterization of a standard route is performed, analyzing the average power consumption and the most frequent working points of an internal combustion engine (ICE) in real routes. This information is used to define alternative powertrain architectures. A hybrid hydraulic powertrain architecture is proposed and modelled. The proposed powertrain model is executed using two different control algorithms, with and without predictive strategies, with data obtained from real routes. A calculation engine (an algorithm which runs the vehicle models on real routes), is presented and used for simulations. This calculation engine has been specifically designed to analyze if the different alternative powertrain delivers the same performance of the original ICE. Finally, the overall performance of the different architectures and control strategies are summarized into a fuel and energy consumption table, which will be used in the second part of this paper to compare with the different architectures based on hybrid electric powertrain. The overall performance of the different architectures indicates that the use of a hybrid hydraulic powertrain with simple control laws can reduce the fuel consumption up to a 14 %. 相似文献
124.
FlexRay is a reliable and hard real-time in-vehicle communication protocol that is strongly promoted by car manufacturers as the de facto standard in the automotive domain. The protocol offers both a time-triggered and an eventtriggered architecture. This paper focuses on the optimal scheduling of the time-triggered component of FlexRay known as the static (ST) segment using a two-dimensional bin-packing technique. To maximize the bandwidth utilization in the ST segment, a fast heuristic as well as an efficient integer linear programming approach are proposed. Our methods directly schedule signals into slots including frame packing, according to signal-based data scheduling and the slot/ cycle multiplexing mechanisms presented by the latest version of the FlexRay protocol. The benefits of our proposed methods are demonstrated by extensive experiments on synthetic and an automotive X-by-wire system case study. An additional test case is examined to emphasize the superior performance of the proposed approach relative to that of existing optimal scheduling approaches. 相似文献
125.
Seoungbum Kim 《智能交通系统杂志
》2017,21(3):179-189
》2017,21(3):179-189
Traffic speed is a crucial input for real-time traffic management applications. Operating agencies typically deploy their own sensors to collect the measurements, e.g., loop detectors. Recently, SpeedInfo emerged with a different paradigm for traffic speed collection: instead of selling hardware to operating agencies, at each link the company deploys its own Doppler radar in a self-contained wireless unit to measure traffic speeds and then sells the speed data. This study uses well-tuned loop detector-based speed measurements to evaluate 15 of the Doppler radar sensors over several months while the two traffic data collection systems were operating concurrently. The extended study period includes potentially challenging and transient conditions for the radar sensors: both recurrent (rush hour congestion and late night low flow) and nonrecurrent (incidents and precipitation). The analysis took a broad overview, comparing speed measurements from the radar sensors against the concurrent loop detector data and then explicitly looked for any anomalous pattern in the radar data such as latency and system outages. The work found the radar measurements are generally good, but also identified several points that should be considered before deployment, including latency, different biases in free flow and congestion, vulnerability to precipitation, and sensitivity to mounting angle. 相似文献
126.
M. S. Roe 《Maritime Policy and Management》1999,26(1):69-79
This paper will examine the impact of continuous and increasing change in the shipping sector of Eastern Europe with particular reference to the liner sector in Poland one of the more dynamic markets that has emerged since the political, economic and social changes of the late 1980s. Polish Ocean Lines, and in particular POL Levant, a relatively new, commercialized subsidiary operating in the private sector, are taken as case studies to assess the new structures that are emerging in the marketplace. 相似文献
127.
Fast and predictive simulation tools are prerequisites for pursuing simulation based engine control development. A particularly
attractive tradeoff between speed and fidelity is achieved with a co-simulation approach that marries a commercial gas dynamic
code WAVE™ with an in-house quasi-dimensional combustion model. Gas dynamics are critical for predicting the effect of wave
action in intake and exhaust systems, while the quasi-D turbulent flame entrainment model provides sensitivity to variations
of composition and turbulence in the cylinder. This paper proposes a calibration procedure for such a tool that maximizes
its range of validity and therefore achieves a fully predictive combustion model for the analysis of a high degree of freedom
(HDOF) engines. Inclusion of a charge motion control device in the intake runner presented a particular challenge, since anything
altering the flow upstream of the intake valve remains “invisible” to the zero-D turbulence model applied to the cylinder
control volume. The solution is based on the use of turbulence multiplier and scheduling of its value. Consequently, proposed
calibration procedure considers two scalar variables (dissipation constant C
β
and turbulence multiplier C
M
), and the refinements of flame front area maps to capture details of the spark-plug design, i.e. the actual distance between
the spark and the surface of the cylinder head. The procedure is demonstrated using an SI engine system with dual-independent
cam phasing and charge motion control valves (CMCV) in the intake runner. A limited number of iterations led to convergence,
thanks to a small number of adjustable constants. After calibrating constants at the reference operating point, the predictions
are validated for a range of engine speeds, loads and residual fractions. 相似文献
128.
This paper describes the hydrographic conditions observed during six surveys carried out during 2003 and 2004, in the framework of the “IDEA Project” (acronym for “Influence of oceanographic structure and dynamics on demersal populations in waters of the Balearic Islands”). The surveys were developed on the shelf and slope of Mallorca Island, in particular in two fishing grounds at the north and south of the Mallorca channel. Periodic movements of the fishing fleet between these two areas have been regularly reported, suggesting a seasonal variability of the resources which could be in turn associated with the hydrodynamic variability. With this motivation, water masses affecting these grounds have been identified and their seasonal variability has been studied. Different oceanographic and environmental conditions have been found between the two fishing grounds. These differences are related to the presence of mesoscale structures, associated with the Western Mediterranean Intermediate Water (WIW) at the north of the Ibiza channel and big gyres detached from the Algerian Current. The former has been shown to have influence on the regional oceanic circulation and the latter could affect the progress of fresh Atlantic Water (AW) towards the channels and make possible the presence of high salinity values at intermediate waters at the south of Mallorca Island. Historical data from other oceanographic cruises carried out in the region are finally used to discuss the interannual variability of these mesoscale structures. 相似文献
129.
Environmental improvement and energy issues are increasingly becoming more important as worldwide concerns. Natural gas is
a good alternative fuel that can help to improve these issues because of its large quantity and clean burning characteristics.
This paper provides the experimental performance results of a Bi-Fuel engine that uses Compressed Natural Gas as its Primary
fuel and gasoline as its secondary fuel. This engine is a modification of the basic 1.4-liter gasoline engine. Generally,
on the unmodified base engine, torque and power for CNG fuel are considerably lower than gasoline fuel. In this paper, the
influence of fuels on wall temperature, performance and emissions are investigated. 相似文献
130.
In the present work, different ventilated disc brake rotor configurations were analysed to enhance the heat transfer rate and obtain the uniform temperature distribution in the rotor. CFD code used in this work was validated at using experimental results obtained by conducting experiments on a test rig. The experimental analysis was performed to calculate the mass flow rate and heat dissipation through the rotor. Further, different types of rotor configurations viz. straight radial vane (SRV), tapered radial vane (TRV), alternate long and short vane (ALSV), variable diameter circular pillars (VDCP) were considered for the analysis. A rotor segment of 20° was considered for the numerical analysis due to its rotational symmetry. CFD results were in good agreement with the experiments. The maximum deviation of the numerical results were about 12 % from the experimental results. It is found from the analysis that among the different types of rotor configurations; variable diameter circular pillars (VDCP) rotor gives better rate of heat dissipation with more uniform temperature distribution in the flow passages. Hence for modern high speed vehicles VDCP rotor may be more appropriate. 相似文献