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341.
Design of conformal cooling channels for an automotive part 总被引:2,自引:0,他引:2
The cooling system plays a crucial role in determining the productivity and quality of an injection molding process. With
the current growth of Solid Freeform Fabrication (SFF) techniques, mold designers have been striving for not only improvement
in cooling system performance but also for a method to do so automatically. In this paper, a method is proposed for developing
a conformal cooling system that facilitates uniform cooling over the entire mold surface with minimum cycle time. Based on
the temperature distribution after the filling stage, the mold surface is split into zones which will be cooled by optimized
subconformal channels obtained from the optimization process. The optimization process in which the objective function is
stated as minimization of the cooling time with boundaries ensuring a realistic design will optimize the cooling system layout
in terms of cooling channel size and location. Finally, all subcooling channels are combined to generate the entire conformal
cooling system for the injection mold. 相似文献
342.
J. Kim N. Kim S. Hwang Y. Hori H. Kim 《International Journal of Automotive Technology》2009,10(6):733-742
A motor control strategy for an input-split hybrid electric vehicle (HEV) is proposed. From a power characteristic analysis,
it is found that the powertrain efficiency decreases for speed ratios at which power circulation occurs. Using dynamic models
of an input-split HEV powertrain, a motor-generator control algorithm for obtaining high system efficiency is designed by
inversion-based control. The performance of the control algorithm is evaluated by the simulator which is developed based on
PSAT, and simulation results are compared with the test results. It is found that, even if the engine thermal efficiency is
sacrificed by moving the engine operation point from the OOL for the control strategy, improved overall powertrain system
efficiency can be achieved by the engine operation that gives a relatively high efficiency from the viewpoint of the overall
powertrain efficiency. The control algorithm developed can be used in design of future electric vehicles. 相似文献
343.
In order to plan bus operations, it is necessary for transit planners to understand what factors may influence travelers’ choice of buses for travels within a city. The proposed method involves various scenarios of a hypothetical bus operation which was rated by a group of individuals. Analysis of Covariance technique is employed to analyze people's sensitivities to their perceived levels of bus service characteristics. The technique involves:
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testing for the significant effects of varying levels of service characteristics upon people's intentions to use bus service, and
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assessing differences among various population segments in their sensitivity patterns towards bus service characteristics.
344.
The paper introduced a special approach for diesel‘s all-speed-governor modeling, which, in some cases,could solve the knotty problem frequently met in computer simulation of diesel propulsion system or diesel generating set. Suppose that it is hard to get a control-oriented governor mathematical model when the general approaches, the analytical approach or the experimental approach, are applied, and that an open-loop step response of the diesel engine and its system is available by means of computer simulation, the critical three parameters of a governor mathematical model, the proportional gain Kp, integral time constant Ki, and derivative time constant Kd, can be determined by use of PID tuning method which are widely applied in industrial process control. This paper discussed the train of thought of the approach, precondition, procedure, several modifications of the classical PID model, and some points for attention. A couple of case studies were given to demonstrate the effectiveness of this approach. 相似文献
345.
Various water wave problems involving an infinitely long horizontal cylinder floating on the surface water were investigated
in the literature of linearized theory of water waves employing a general multipole expansion for the wave potential. This
expansion involves a general combination of a regular wave, a wave source, a wave dipole and a regular wave-free part. The
wave-free part can be further expanded in terms of wave-free multipoles which are termed as wave-free potentials. These are
singular solutions of Laplace’s equation (for non-oblique waves in two dimensions) or two-dimensional Helmholz equation (for
oblique waves) satisfying the free surface condition and decaying rapidly away from the point of singularity. The method of
constructing these wave-free potentials is presented here in a systematic manner for a number of situations such as deep water
with a free surface, neglecting or taking into account the effect of surface tension, or with an ice-cover modelled as a thin
elastic plate floating on water. 相似文献
346.
Determining the number and location of depots for winter road maintenance (WRM) represents one of the important strategic decisions while planning WRM activities. However, most organizations dealing with WRM make empirically based decisions. Optimizing the number and location of WRM depots has the potential to achieve considerable cost savings, improve mobility and efficiency, as well as reduce environmental impacts. This paper presents two optimization models. The first model determines the location of WRM depots by minimizing the total distance travelled by maintenance vehicles. The second model determines the optimum number and location of WRM depots by minimizing total transportation costs and capital expenditure and operational expenditure of the depots. The models are then applied to the district road network in Serbia. Results show that their application could lead to significant reductions in WRM costs. 相似文献
347.
The current article proposes an approach to accommodate flexible spatial dependency structures in discrete choice models in
general, and in unordered multinomial choice models in particular. The approach is applied to examine teenagers’ participation
in social and recreational activity episodes, a subject of considerable interest in the transportation, sociology, psychology,
and adolescence development fields. The sample for the analysis is drawn from the 2000 San Francisco Bay Area Travel Survey
(BATS) as well as other supplementary data sources. The analysis considers the effects of a variety of built environment and
demographic variables on teenagers’ activity behavior. In addition, spatial dependence effects (due to common unobserved residential
neighborhood characteristics as well as diffusion/interaction effects) are accommodated. The variable effects indicate that
parents’ physical activity participation constitutes the most important factor influencing teenagers’ physical activity participation
levels, In addition, part-time student status, gender, and seasonal effects are also important determinants of teenagers’
social-recreational activity participation. The analysis also finds strong spatial correlation effects in teenagers’ activity
participation behaviors. 相似文献
348.
349.
地铁工程施工事故与风险管理 总被引:4,自引:0,他引:4
参考国际隧道协会所建议的分级系统,将2001-2006年间在亚太地区地铁工程施工期间所发生的43个事故,依其后果的严重性分级,以作为发展地下工程风险管理的基础.纳入考量的项目包括人员伤亡、经济损失及对民众生活的影响、工期的延误,以及对交通的影响.并以新加坡政府在尼诰大道灾变后所采取的一连串措施为例,列出地下工程风险管理的要素,勾画出地铁风险管理制度的基本架构. 相似文献
350.
Haneen Farah Haris N. KoutsopoulosMohammad Saifuzzaman Robert KölblSusanne Fuchs Doris Bankosegger 《Transportation Research Part C: Emerging Technologies》2012,21(1):42-56
In-vehicle technologies and co-operative services have potential to ease congestion problems and improve traffic safety. This paper investigates the impact of infrastructure-to-vehicle co-operative systems, case of CO-OPerative SystEms for Intelligent Road Safety (COOPERS), on driver behavior. Thirty-five test drivers drove an instrumented vehicle, twice, with and without the system. Data related to driving behavior, physiological measurements, and user acceptance was collected. A macro-level approach was used to evaluate the potential impact of such systems on driver behavior and traffic safety. The results in terms of speeds, following gaps, and physiological measurements indicate a positive impact. Furthermore, drivers’ opinions show that the system is in general acceptable and useful. 相似文献