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91.
ABSTRACT Due to the outstanding strength of advanced machine-learning techniques, they have become increasingly common in predictive studies in recent years, particularly in predicting ship energy performance. In constructing predictive models, prior studies have mostly employed vessels’ technical parameters to establish machine-learning algorithms. To bridge this research gap and enable wider applications, this paper presents the design of a multilayer perceptron artificial neural network (MLP ANN) as a machine-learning technique to estimate ship fuel consumption. We utilized the real operational data from 100–143 container ships to estimate fuel consumption for five different container ships grouped by size. We compared the performance of two ANN models and two multiple-regression models. Four input parameters (sailing time, speed, cargo weight, and capacity) were included in the first ANN and the first regression model, while the other two models only consider two inputs from physical function. The mean absolute percentage error of the ANN models with four inputs was the smallest and less than those in extended statistical models, demonstrating the MLP’s superiority over the statistical model. The MLP ANN model can thus be applied to confirm the effectiveness of the slow-steaming method for achieving energy efficiency. 相似文献
92.
In digital ship-design processes, surface modeling needs to be as accurate as possible for effectiveness in ship production
as well as numerical analysis of the performance. Traditionally, the form of a ship hull is constructed from a set of cross-sectional
data. This approach entails difficulties in the cross-sectional spacing and accuracy of the characteristic curves, such as
the stern and bow profiles, deck side line, bottom tangential line, and unconnected curves. Genetic algorithms (GAs) have
attracted increasing attention as a multimodal optimization solution for surface reconstruction that enable construction of
a single non-uniform B-spline (NUB) surface at the initial stage of ship design with constraints such as knuckles, discontinuity
conditions, and bulbous bows with high curvatures, . The first, simultaneous multi-fitting GA determines the boundary curves,
such as the stem and stern profiles, and finds the common knot values for both curves. Similarly, the same GA technique is
applied for other boundary curves at the bottom and the deck. The second GA is employed to fit the interior data points after
the boundary curves are fitted. The encoded design variables for surface construction are the locations of the vertices and
the knot values. Those variables are modified for improving the surface quality until a predefined degree of precision is
attained. In four instances of application, the GA technique developed in this research has been shown to provide good, single,
NUB surfaces with high efficiency. In the early design stage, a single NUB surface is more convenient for performance visualization
and finite-element methods. It can be readily translated into many CAD/CAM packages, which facilitate the smooth transition
of data across the different design stages. 相似文献
93.
Keon Hee Baek Su Bin Choi Hee Rok Hong Nak Tak Jeong Hyeong Uk Moon Eun Seong Lee Hyung Min Kim Sung Uk Choi Myung Won Suh 《International Journal of Automotive Technology》2018,19(5):859-868
Ever since vehicle noise, vibration, and harshness (NVH) reduction technology made dramatic improvements, vehicle interior noises represented by Squeak and Rattle (S/R) becomes an ever more important factor to improve the emotional quality of vehicles. Generally, people detect S/R noises on automotive interior parts, brake system, suspension, Body in White (BIW), etc. Among them, the rear-glass joint is a major source for vehicle interior noise, and can cause S/R noises under a variety of environmental and driving conditions. This study uses, two approaches, experimental and numerical approaches, to define the cause of S/R noise at the rear-glass section. Based on these two approaches, this study confirms that S/R noises generate through the contact between bottom side of molding and BIW. The sealant penetration length, panelmolding distance, and sealant width are the parameters affecting noise generation. In addition, this study created an optimal design with Design of Experiments (DOE) of the rear-glass joint. The design maximized the sealant penetration length, which is a parameter that majorly affects noise. The optimal design comprises of two steps: sealant injections shape optimization and rear-glass joint parameter optimization. Each step is carried out with FEA and validated by sealant penetration experiments. Through these optimizations, this study obtained an optimum combination of design parameters and fignificantly reduced the noise generated by rear-glass section. 相似文献
94.
The purpose of this paper is to implement an efficient method for GIS‐based traffic analysis zone (TAZ) design in order to evaluate and validate such a method. The method was developed by the authors. Moran's I spatial autocorrelation coefficient and sample variance are used for evaluating the generated TAZs using the Champaign‐Urbana, IL region as a case study. Sensitivity analysis is also conducted to explore the fluctuations in TAZ generation outcomes. The evaluation, the validation as well as the TAZ design have been implemented with ARC/INFO GIS software on a UNIX workstation platform. 相似文献
95.
Benjamin Coifman SeoungBum Kim 《Transportation Research Part C: Emerging Technologies》2009,17(4):349-364
Roadway usage, particularly by large vehicles, is one of the fundamental factors determining the lifespan of highway infrastructure. Operating agencies typically employ expensive classification stations to monitor large vehicle usage. Meanwhile, single-loop detectors are the most common vehicle detector and many new, out-of-pavement detectors seek to replace loop detectors by emulating the operation of single-loop detectors. In either case, collecting reliable length data from these detectors has been considered impossible due to the noisy speed estimates provided by conventional data aggregation at single-loop detectors. This research refines non-conventional techniques for estimating speed at single-loop detectors, yielding estimates that approach the accuracy of a dual-loop detector’s measurements. Employing these speed estimation advances, this research brings length based vehicle classification to single-loop detectors (and by extension, many of the emerging out-of-pavement detectors). The classification methodology is evaluated against concurrent measurements from video and dual-loop detectors. To capture higher truck volumes than empirically observed, a process of generating synthetic detector actuations is developed. By extending vehicle classification to single-loop detectors, this work leverages the existing investment deployed in single-loop detector count stations and real-time traffic management stations. The work also offers a viable treatment in the event that one of the loops in a dual-loop detector classification station fails and thus, also promises to improve the reliability of existing classification stations. 相似文献
96.
绿色道路:路面可持续性评价系统 总被引:3,自引:0,他引:3
绿色道路是评价路面设计和施工过程相关的可持续性发展的一种建议标准。该系统依据可持续发展的实践性为道路工程打分,通过得分的高低来评价工程的可持续性。充分完善的绿色道路系统具有以下内容和功能:1)鼓励更多道路工程尝试可持续性的实践;2)为道路可持续性评价提供一种标准和方法;3)使工程设计更优;4)使业主单位能评判道路工程的优劣。绿色道路评价系统通过6大类的54个评分项完成对道路工程的评分,是发展道路可持续性设计的可靠系统。 相似文献
97.
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
98.
Xiaohui Cui Hoe Kyoung Kim Cheng Liu Shih-Chieh Kao Budhendra L. Bhaduri 《Transportation Research Part D: Transport and Environment》2012,17(7):548-554
This paper presents a multi agent-based simulation framework for modeling spatial distribution of plug-in hybrid electric vehicle ownership at local residential level, discovering “plug-in hybrid electric vehicle hot zones” where ownership may quickly increase in the near future, and estimating the impacts of the increasing plug-in hybrid electric vehicle ownership on the local electric distribution network with different charging strategies. We use Knox County, Tennessee as a case study to highlight the simulation results of the agent-based simulation framework. 相似文献
99.
Myung-Seop Lim Dong-Min Kim Jung-Pyo Hong 《International Journal of Automotive Technology》2017,18(3):499-504
This paper deals with the speed response characteristic of the concentrated flux synchronous motor (CFSM) using ferrite magnets for the electric power steering (EPS) system. To analyze the response characteristic of the CFSM, an analytical method using the electromechanical undamped natural frequency and damping ratio based on the transfer function is proposed. By using the method, the speed response according to the variations of the shape of the permanent magnets (PMs) and rotor core is analyzed. It was analyzed under the conditions of the constant volume of the PMs as well as the constant diameter of the rotor. By using the proposed analysis method, the improved model is desgined based on the initial model fulfilling the required specifications. Finally, the torque and speed response characteristics of two motors are simulated through the finite element analysis (FEA) and MATLAB Simulink. 相似文献
100.
The squeal noise occurring from the disc brakes of passenger cars has been analyzed by using the complex eigenvalue method numerically. The contact between a disc and two pads was analytically modeled as many linear springs and dampers in an effort to develop the improved equation of motion derived on the basis of Lagrange’s equation and the assumed mode method. The finite element modal analysis results for disc brake components constitute an eigenvalue matrix in the analytical equation of motion. The complex eigenvalue analyses based on the equations of motion are able to examine the dynamic instability of a brake system, which is an onset of squeal, by considering the disc rotational effect. Numerical analyses showed that the modes unstable in an undamped analysis became stable in a damped case, which illustrates the important effect of damping on the squeal instability in a brake squeal simulation. Then several modified brake models were suggested and investigated how effectively they suppressed the occurrence of squeal noise. The brake parts such as a pad chamfer and a disc vane were modified and the influence of pad chamfer and vane shapes on squeal occurrence was proved to be significant. The numerical results showed that proper structural modification of a disc brake system can suppress the brake squeal to some extent. 相似文献