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261.
An optimization technique was used to generate a wing-in-ground-effect (WIG) configuration which can achieve the maximum lift
and satisfy the height stability criteria within the design constraints. For the analysis of the aerodynamic coefficients,
the vortex lattice method (VLM) was applied with the inviscid and potential flow approximations. The sequential quadratic
programming (SQP) method, which is a nonlinear optimization method, was employed as an optimization tool. The lift and moment
coefficients, including the stability analysis computed by VLM, were compared with the experimental results of a medium-sized
WIG, and a good correlation was found between them. In addition, the optimization tool was validated by finding the optimal
position of the side wing attached on the WIG craft. Then, various optimum examples are shown, with generation of the wing
section, the determination of the planform configuration, the aspect ratio, and the position of the tail wing within the design
constraints. It was shown that the present optimization tool can be used effectively for the optimal design of a WIG craft. 相似文献
262.
The seasonal variation of the surface circulation in the Japan/East Sea (JES) and the Tsushima/Korea Straits (TKS) is reviewed and discussed, focusing on mesoscale and submesoscale variabilities.The monsoon modified by coastal geographical features near Vladivostok generates a dipole of vortex off Vladivostok which induces dramatic changes in the surface circulation in the northwest JES, splitting the Subpolar Gyre into two smaller gyres by generating the Vladivostok Dome. Between these two smaller gyres, the Northwest Thermal Front is formed and current reversal is induced along the North Korean coast. The winter monsoon also induces a current reversal along the Sakhalin coast. The volume transport of the surface Subpolar Gyre has two maxima in January and August. The maximum in August is induced by the summer intensification of the Liman-North Korean Cold Current and the shallow and narrow surface coastal jet generated by the sea ice and snow melting. The maximum in January is induced by the northwest monsoon and associated cooling.Salient features in the TKS are the submesoscale variabilities. In the western channel, submesoscale eddies with length scale of about 80 km and time scale of 5–6 days develop in the cold period. On the lee side of the Tsushima Islands, Karman-like vortex pairs are generated in the warm period. Anticyclonic vortices generated at the northern tip of the Tsushima Islands have a time scale of 5 to 8 days, length scale of 35 to 60 km, and propagate toward the JES with a phase speed of 8 cm/s. Cyclonic vortices south of the anticyclonic counter part of the vortex pairs are rather stationary with intermittent occasional propagation toward the east. The development of stratification seems to be necessary for the development of Karman-like vortex pairs.Summarizing the results above, a schematic surface circulation with seasonal change is proposed. 相似文献
263.
Yoo-Chul Kim Youn-Mo Lee Myeong-jo Son Tae-wan Kim Jung-Chun Suh 《Journal of Marine Science and Technology》2009,14(3):275-284
We generate cutter paths free of interference and gouging for manufacturing model propellers using a five-axis numerical control
(NC) machine. Our approach is faster than using a general-purpose computer-aided design (CAD)/computer-aided manufacturing
(CAM) system. A roughing cut is made using only three axes for efficiency, and the finishing cut is made using all five axes
to avoid collisions. Elements of the cutter path that might produce gouging are eliminated and the pose of the cutter is adjusted
to eliminate interference. A number of models, including surface-piercing propellers, have been manufactured. 相似文献
264.
In this paper, a powerful tool for analyzing motor vehicle data based on the vector quantization (VQ) technique is demonstrated. The technique uses an approximation of a probability density function for a stochastic vector without assuming an “a priori” distribution. A self‐organizing map (SOM) is used to transform accident data from an N‐dimensional space into a two‐dimensional plane. The SOM retains all the original data yet provides an effective visual tool for describing patterns such as the frequency at which a particular category of events occurs. This enables new relationships to be identified. Accident data from three cities in Italy (Turin, Milan, and Legnano) are used to illustrate the usefulness of the technique. Crashes are aggregated and clustered crashes by type, severity, and along other dimensions. The paper includes discussion as to how this method can be utilized to further improve safety analysis. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
265.
Namkug Ku Ju-hwan Cha Kyu-Yeul Lee Jongwon Kim Tae-wan Kim Sol Ha Donghun Lee 《Journal of Marine Science and Technology》2010,15(4):374-385
This paper describes the development of a self-driving mobile welding robot. The robot is used to weld U-shaped welding areas
in enclosed double-hull structures. In order to place itself inside the double-hull structure, the robot is capable of passing
through an access hole 600 mm wide and 800 mm high. This research addresses the mechanical and control systems of the robot.
The mechanical system of the robot consists of an eight-axis mobile platform, and a six-axis welding unit. The control system
consists of a main controller, a welding machine controller (arc sensor board), and seam tracking sensors, i.e., a touch sensor,
a laser sensor, and an arc sensor. To reduce the number of cables that would be dragged by the welding robot, the main controller
is designed as an embedded type that is mounted on the back of the mobile platform. 相似文献
266.
Recent improvements in the quality of life have led to a consumer need for emotional quality. This need is regarded as extremely
important, particularly for products that require a close interaction between products and users and thus that directly lead
to product purchase. As a result, research on how to design user-friendly products has become an important task for corporations.
Discomfort evaluation in product use has been extensively researched for this purpose. Most of the research concludes that
the joint angles of the human body are the main cause of discomfort and propose a discomfort evaluation method based on joint
angles. In general, when a person uses great force, they feel discomfort, and the level of discomfort varies depending on
the size of the force. Accordingly, it can be inferred that the force acting on the muscle is one of the important causes
of discomfort, and research on the correlation between discomfort and muscle forces is needed. In this study, the authors
developed a method to evaluate discomfort during ingress into a vehicle to design a side panel for comfortable ingress into
a vehicle. The correlation between the muscle forces and discomfort was investigated, and a discomfort evaluation method based
on muscle forces was developed. To calculate the muscle forces during the ingress motion, an experimental mock-up of a vehicle
was made, and a motion capture experiment during the ingress motion was conducted with various side panel design parameters.
The biomechanical simulation tool was used to perform motion simulation based on the motion data obtained. The mathematical
correlation between the calculated muscle forces and discomfort was obtained by means of fuzzy logic, and the discomfort evaluation
method developed in this study was used to propose a method for designing a comfortable side panel for a vehicle. 相似文献
267.
H. Yang B. Kim Y. Park W. Lim S. Cha 《International Journal of Automotive Technology》2009,10(3):381-390
In recent studies, various types of multi-mode electric variable transmissions for hybrid electric vehicles have been proposed.
A multi-mode electric variable transmission consists of two or more different types of a planetary gear hybrid powertrain
system (PGHP), which can change power flow type using clutches to improve transmission efficiency. Input split systems are
generally used for the single-mode powertrain because of their overall superiority, but other power split systems such as
output split and compound split systems can be used in the dual-mode powertrain. In this study, we analyze the power transmission
characteristics of output split systems, and evaluate their fuel economies in the FTP72 cycle, acceleration performance, and
constant vehicle speeds. These results enable the selection of appropriate systems for a dual-mode powertrain. 相似文献
268.
Jinsoo You Tschangho John Kim 《Transportation Research Part C: Emerging Technologies》2000,8(1-6):231-256
The purpose of this paper is to develop and evaluate a hybrid travel time forecasting model with geographic information systems (GIS) technologies for predicting link travel times in congested road networks. In a separate study by You and Kim (cf. You, J., Kim, T.J., 1999b. In: Proceedings of the Third Bi-Annual Conference of the Eastern Asia Society for Transportation Studies, 14–17 September, Taipei, Taiwan), a non-parametric regression model has been developed as a core forecasting algorithm to reduce computation time and increase forecasting accuracy. Using the core forecasting algorithm, a prototype hybrid forecasting model has been developed and tested by deploying GIS technologies in the following areas: (1) storing, retrieving, and displaying traffic data to assist in the forecasting procedures, (2) building road network data, and (3) integrating historical databases and road network data. This study shows that adopting GIS technologies in link travel time forecasting is efficient for achieving two goals: (1) reducing computational delay and (2) increasing forecasting accuracy. 相似文献
269.
Kim Bang Salling David Banister 《Transportation Research Part A: Policy and Practice》2009,43(9-10):800-813
This paper presents a newly developed decision support model to assess transport infrastructure projects: CBA-DK. The model combines use of conventional cost–benefit analysis to produce aggregated single point estimates, with quantitative risk analysis using Monte Carlo simulation to produce interval results. The embedded uncertainties within traditional CBA such as ex-ante based investment costs and travel time savings are of particular concern. The paper investigates these two impacts in terms of the Optimism Bias principle which is used to take account of the underestimation of construction costs and the overestimation of travel time savings. The CBA-DK methodological approach has been used to apply suitable probability distribution functions on the uncertain parameters, thus resulting in feasibility risk assessment moving from point to interval results. The proposed assessment model makes use of both deterministic and stochastic based information. Decision support as illustrated in this paper aims to provide assistance in the development and ultimately the choice of action, while accounting for the uncertainties surrounding transport appraisal schemes. The modelling framework is illustrated by the use of a case study appraising airport and runway alternatives in the capital of Greenland – Nuuk. The case study has been conducted in cooperation with the Home Rule Authorities of Greenland. 相似文献
270.
Using MATLAB/Simulink, we constructed a comprehensive simulation model for the fuel cell hybrid vehicle (FCHV) power train in parallel with a power control strategy that uses a logic threshold approach implemented with a hybrid control unit (HCU). The simulation implements power flow and power distribution under different vehicle operating modes using the accelerator and decelerator pedal positions deduced from the driving schedule as primary inputs. The HCU control strategy also incorporates regenerative braking and recharging for recovery of battery capacity. Using the D-optimality method for selection of the optimal experiment values, three control threshold variables for the HCU are selected to maximize the hydrogen fuel economy under certain driving cycles. The proposed method provides the optimal configuration of the FCHV model, which has the capability of achieving the requested drive power while also meeting the vehicle driving schedule and recovery needs of the state of charge (SOC) battery, with lower fuel consumption levels. 相似文献