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1.
Mitsuhisa Ikehata Takeshi Inoue Manabu Ozawa Shinya Matsumoto 《Journal of Marine Science and Technology》1997,2(2):62-76
To examine the flow field of a viscous fluid around the trailing edge of a wing with respect to the Kutta condition or the
Joukowski hypothesis, an experimental investigation into the velocity fields around two-dimensional (2D) wings NACA0012 and
NACA4412 was carried out using an X-type hot-wire anemometer in a wind tunnel and the method of colored milk injection in
a circulating water channel. The results of these investigations revealed that the flow of a viscous fluid at the trailing
edge of a 2D wing is tangential to the face on the pressure side, and that the flow is very slow or reversed on the suction
side due to separation when the angle of attack is greater than 7.5°. By flow visualization, a Kármán vortex street was found
in the wake of both wings (NACA0012 and NACA4412) when the angle of attack was 5°. These results show that the ordinary Kutta
condition with respect to the direction of outflow at the trailing edge is not necessarily satisfied in a viscous fluid, but
the Kutta condition with respect to the pressure at the trailing edge is satisfied as usual. Numerical results, which have
been obtained as the solution of Reynolds-averaged Navier-Stokes equations, show good agreement with above-mentioned experimental
results. Therefore, CFD (Computational Fluid Dynamics) simulation has proved to be very effective for studying steady viscous
flow around the trailing edge of a 2D wing. 相似文献
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Sleepiness is an important factor in traffic accidents caused by human error. The purpose of this paper is to review a number of studies conducted over the years regarding the effect of the lack of sleep on the incidence of traffic accidents as well as the individual effects of various sleep disorders on accidents. In addition, we discuss recent advances in methods of detecting sleepiness and strategies for preventing traffic accident by using these methods. 相似文献
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Shigeru Yamanaka Takayuki Sakanoue Toshikazu Yoshii Tatsuo Inoue . Fundamental Technological Laboratory THK Co. Ltd. Naniwa-ku Osaka Japan . Department of Energy Conversion Science Kyoto University Sakya-ku Kyoto Japan 《上海交通大学学报(英文版)》2000,(1)
IntroductionInelashcorhaersiblestrainaccompaniedbyslidingofcrystalsduetothermalandphasetransformationdilatationiswellknowntointensivelythethedistonionofworkpieceunderqUopching,andsomanynumericalsimulatonsll-7]havebeencAnedoutintheframeworkofmotallochermo-mechwhcsl1].Transformationplasticity(TP),anothekindofbeversiblestrain,isalsorecognizedasoneofdominantparwtersthechngthestr6ssanddistorton,andsomenumcricalcalculationaremadebytakingtheeffectintoconsideration.Figurelschematicallyillustraresthe… 相似文献
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H. Inoue F. Sugasawa 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1993,22(5):425-436
A system incorporating feedforward plus feedback control was configured such that it would follow the target yaw rate found by calculation. Selection of optimum values for the control system constants made it possible to separate control of the steering input response characteristic from control of vehicle stability against external disturbances. The former is controlled by the feedforward control function and the latter by the feedback control function; the values of the two functions can be set independently. 相似文献
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An ecological numerical model has been developed for coastal zone management in Dokai Bay, Japan. The numerical model experiment reproduces the occurrence of red tides and oxygen-deficiency in Dokai Bay during summer. Moreover, the model experiments forecast that when the phosphorus or nitrogen load from land will be cut by 90% or 95%, respectively, red tides and oxygen-deficiency will not occur in Dokai Bay. If the sewage facility is not sufficient to cut the nutrients load to the necessary degree, it is necessary to consider other countermeasures such as cultivating bivalves in order to decrease the nutrients in the bay. 相似文献
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Fatigue crack propagation in marine structures is obviously governed by mechanics of the considerably different four levels of multi-scale problems. Problems of structural response to environmental loads have length scale of several hundred meters, whereas possible detectable size of cracks from initial defects in a weld is of the order of millimeters. Once a fatigue crack initiates, crack tip plasticity is of the order of several grain sizes, while the resulting fatigue crack growth in each load cycle is of the order of nanometers. In our previous work, the first author and their associates have developed the so-called CP-System, which can treat the first two multi-level problems as an integrated system. Furthermore, we have incorporated the third level of mechanics by using the stress intensity range corresponding to the repeated tensile plastic deformation ahead of the crack tip. In the present paper, we shall discuss a more rational integral equation-based formulation in order to integrate the third and fourth levels of micro-mechanics to the first two levels of continuum mechanics.The method is then applied to fatigue crack propagation under the effects of random sequence of clustered loading. As an example of the random sequence of clustered load, we shall use the so-called “storm model”. In the crack propagation simulation, we have to take into account of the plastic wake on the crack surfaces, whose thicknesses are influenced by the material parameters involved in the crack growth model. These parameters are first identified by the fatigue tests under combined constant and random loading using a CT specimen. Then, fatigue crack growth is investigated by numerical simulation and fatigue tests for various random sequences of clustered loading. The experimental and numerical results agree quite well with each other, and fatigue crack propagation is found to be considerably retarded under random sequence loading, so that the conventional equivalent stress approach may provide rather conservative results to the real seaway loading. 相似文献
9.
Multihull vessels have emerged as popular alternatives to conventional monohull ships for high-speed crafts. However, the
bridging structures connecting the hulls are vulnerable to various wave actions and the wave impact on the bottom of them
is the most serious problems associated with multihulled vessels. In this study, prediction of relative wave elevations under
the bridging structures is investigated for multihull ships traveling with forward speed in waves. A computer code YNU-SEA
using the three-dimensional (3D) Green function method with forward speed has been developed and used to analyze the hydrodynamic
radiation and diffraction forces and motion responses for high-speed catamarans in waves. The results of the present calculations
are compared with those of previous calculations as well as with experimental results. The numerical results reveal that the
present computer code can be used as a powerful tool for the accurate numerical computation of seakeeping problems for multihull
ships advancing in waves. Numerical calculations of wave pattern are also carried out including wave interactions between
the hulls to analyze the effects of hull form on the free surface flow around catamarans advancing in waves. The analysis
of the wave pattern allows the determination of relative wave height including radiation and diffraction waves. Finally, some
discussions are included based on these numerical results which may be helpful for the accurate prediction of relative wave
height and wave breaking load on the deck associated with multihull ships. 相似文献
10.
This paper empirically compares the performance of six traffic assignment methods using the same empirical dataset of route
choice. Multinomial logit (MNL), structured multinomial probit (SMNP), user equilibrium (UE), logit-based stochastic user
equilibrium (SUE), probit-based SUE, and all-or-nothing (AON) assignment methods are applied to the comparative analysis.
The investigated methods include those with three types of error components in their cost functions and two types of flow
dependencies. Four methods of generating the route choice set are also compared for use as stochastic traffic assignment methods.
The revealed preference data of urban rail route choice in the Tokyo Metropolitan Area are used for the case analysis. The
empirical case analysis shows that probit-based SUE provides the best accuracy but requires the longest computation time.
It also shows that the heuristics used to generate the choice set influence the method’s accuracy, while the incorporation
of route commonality and in-vehicle congestion significantly improves its accuracy. Finally, the implications for practical
rail planning are discussed on the basis of the analysis results. 相似文献