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541.
Traffic forecasting provides the estimation of future traffic state to help traffic control,travel guide,etc. This paper compared several widely used traffic forecasting methods,and analyzed each one's performance in detail to make conclusions,which could redound to researchers choosing an appropriate traffic forecasting method in their own works. Compared with conventional works,this paper creatively assessed the performance of traffic forecasting methods based on travel time index (TTI) data prediction,wh... 相似文献
542.
A reconfigurable flexible poles die was developed. The die can be used to implement the process of “the multi-point pressing
and forming sheet”. Sheet metal is restricted by the elastic pressing forces putting on the upper and lower surfaces of sheet
in stamping process. The method is an effective way to enhance the buckling critical stresses and reduce wrinkling of sheet.
The results of tests indicate that the die can achieve “one die brings multi-purpose” and suppress the wrinkle of sheet. The
process of the multi-point pressing and forming sheet provides a practical and effective way for the curved sheet metal forming. 相似文献
543.
本文结合实际工程的施工,通过对瓦斯隧道施工中瓦斯涌出量、通风风量计算和通风设备的选定、瓦斯检测和监控体系、电气设备的选用和管理等方面的分析,进一步明确了瓦斯隧道施工中通风技术重要性,为同行业在瓦斯隧道施工中提供了一定的借鉴作用. 相似文献
544.
This study focuses on the user-interface of the route guidance system with an electronic map display. The ultimate goal of
the study is to aid in designing electronic map displays that can deliver information to the user most efficiently and expeditiously
with minimum confusion. To evaluate the efficiency and understandability of a map display, laboratory experiments were designed
and conducted in this study. In the experiments the subjects were presented with electronic map displays of different attributes
and performed a set of tasks. Their understanding of the information contents was measured based on the outcomes of the tasks,
and subjective ratings of the ease of using the maps were obtained. Using the experimental data obtained, a structural equations
model system is developed to explain the understandability of a map display in terms of the subject’s attributes and the characteristics
of the map display. The experimental procedure and the modeling results are presented in this paper. 相似文献
545.
546.
Naoya Umeda Hirotada Hashimoto Shohei Minegaki Akihiko Matsuda 《Journal of Marine Science and Technology》2008,13(1):16-23
The parametric rolling of modern containerships is emerging as a serious problem, to the extent that its effects warrant a
study into its prevention. In light of this, two methods for reduction of parametric rolling are proposed and examined by
physical model experiments. The first is a sponson attached to the side of a ship, the purpose being to decrease the rate
of change of the rollrestoring moment. The second is an antirolling tank to increase roll damping. By conducting free-running
model experiments for a 6600-TEU post-Panamax container ship with sponsons under typical parametric rolling conditions, it
was found that the sponsons could decrease the magnitude of parametric rolling. The antirolling tank could prevent parametric
rolling completely in certain conditions, even in severe head seas. Using the damping coefficients from experimentally derived
data of a model ship with an antiroll tank, a numerical simulation was established. The numerical model was then compared
with the free-running model experiments. The results indicated that the numerical model could qualitatively verify the experimental
results. Finally, an attempt to optimise the size of an antirolling tank for preventing parametric rolling for the subject
post-Panamax container ship in the North Pacific Ocean is presented. 相似文献
547.
股市中有这样一个名词,蓝筹股.所谓"蓝筹",其提法最早起源于赌场,各国赌场中的大面额筹码一般是蓝色的,由此引申到股市,就产生了"蓝筹股"一说.从经验来看, "蓝筹公司"一般指那些业绩稳定、在行业内居于龙头地位的企业,其经营状况也会随着市场的波功而摇摆,但长期会呈现出稳定增长的趋势. 相似文献
548.
Yusuke Tahara Daniele Peri Emilio Fortunato Campana Frederick Stern 《Journal of Marine Science and Technology》2008,13(2):95-116
The main objective of this article is to describe the development of two advanced multiobjective optimization methods based
on derivative-free techniques and complex computational fluid dynamics (CFD) analysis. Alternatives for the geometry and mesh
manipulation techniques are also described. Emphasis is on advanced strategies for the use of computer resource-intensive
CFD solvers in the optimization process: indeed, two up-to-date free surface-fitting Reynolds-averaged Navier-Stokes equation
solvers are used as analysis tools for the evaluation of the objective function and functional constraints. The two optimization
methods are realized and demonstrated on a real design problem: the optimization of the entire hull form of a surface combatant,
the David Taylor Model Basin—Model 5415. Realistic functional and geometrical constraints for preventing unfeasible results
and to get a final meaningful design are enforced and discussed. Finally, a recently proposed verification and validation
methodology is applied to assess uncertainties and errors in simulation-based optimization, based on the differences between
the numerically predicted improvement of the objective function and the actual improvement measured in a dedicated experimental
campaign. The optimized model demonstrates improved characteristics beyond the numerical and experimental uncertainty, confirming
the validity of the simulation-based design frameworks. 相似文献
549.
以上海港为研究对象,通过构建了上海港物流发展水平评价的指标体系,利用因子分析法和主成份分析法进行对比分析,研究结果表明上海港目前在港口物流量的规模和腹地经济实力方面具有绝对的优势,而在港口物流发展速度和高附加值的国际物流的发展方面却有很大的发展空间。 相似文献
550.
This paper presents the numerical analysis of rudder cavitation in propeller slipstream and the development of a new rudder
system aimed for lift augmentation and cavitation suppression. The new rudder system is equipped with cam devices which effectively
close the gap between the horn/pintle and movable wing parts. A computational fluid dynamics code that solves the Reynolds-averaged
Navier–Stokes equations is used to analyze the flow field of various rudder systems in propeller slipstream. The body force
momentum source terms that mimic flow field behind a rotating propeller are added in the momentum equations to represent the
influence of the propeller and its slipstream. For detailed explication of the new rudder system’s lift augmentation and cavitation
suppression mechanism, three-dimensional flow analysis is carried out. Simulations clearly display the mechanism of the lift
augmentation and cavitation suppression. The computational results suggest that the Reynolds-averaged Navier–Stokes-based
computational fluid dynamics reproduces the flow field around a rudder in propeller slipstream and that the present concept
for a cavitation suppressing rudder system is highly feasible and warrant further study for inclusion of the interaction with
hull and mechanical design for manufacturing and operations. 相似文献