Development of the brake system design program for a vehicle

It is quite challenging to estimate the braking performance of a vehicle because the brake system is comprised of many parts, including a booster, master cylinder, and caliper. Calculation of characteristics such as braking force through vehicle tests requires much time and money. Therefore, the development of a method to estimate the braking performance of a vehicle using qualitative methods is beneficial. In this study, a program that can analyze the braking capabilities of a vehicle such as pressure, efficiency, and pedal travel is presented. The increase in disc temperature during braking as well as the properties of various boosters can be calculated using the proposed program. Dynamic characteristics of a vehicle equipped with a Load Sensing Proportional Valve (LSPV) were computed more precisely by obtaining the change in valve pressure according to the displacement of a suspension system. Since all input and output files are composed in the Microsoft Excel format, both design data management and database construction can easily completed.     

Experimental investigation of abrasive flow machining effects on injector nozzle geometries,engine performance,and emissions in a di diesel engine

The effects of the Abrasive Flow Machining (AFM) process on a direct injection (DI) Diesel engine fuel injector nozzle are studied. Geometry characterization techniques were developed to measure the microscopic variations inside the nozzle before and after the process. This paper also provides empirically-based correlations of the nozzle geometry changes due to the AFM process. The resulting impact of the process on the engine performance and emissions are also assessed with a DI Diesel engine test setup. This study shows that properly AFM-processed injectors can enhance engine performance and improve emissions due to the improved quality of the nozzle characteristics. However, an extended process can also cause enlargement of the nozzle hole as a side effect, which can adversely affect emissions. Emission measurements show the trade-off for the minimum levels as the process proceeds. Since the enlargement of the hole during the AFM process is not avoidable and must be minimized, strict control over the process is required. This control can be enforced by either limiting the AFM processing period, or by properly preparing the initial hole diameter so as to accommodate the inevitable changes in the nozzle geometry.     

Experimental investigation and comparison of nanoparticle emission characteristics in light-duty vehicles for two different fuels

In recent years, particle number emissions rather than particulate mass emissions in automotive engines have become the subject with controversial discussions. Recent results from studies of health effects imply that it is possible that particulate mass does not properly correlate with the variety of health effects attributed to engine exhaust. The concern is now focusing on nano-sized particles emitted from I. C. engines. In this study, particulate mass and particle number concentration emitted from light-duty vehicles were investigated for a better understanding of the characteristics of the engine PM from different types of fuels, such as gasoline and diesel fuel. Engine nano-particle mass and size distributions of four test vehicles were measured by a condensation particle counter system, which is recommended by the particle measurement program in Europe (PMP), at the end of a dilution tunnel along a NEDC test mode on a chassis dynamometer. We found that particle number concentrations of diesel passenger vehicles with DPF system are lower than gasoline passenger vehicles, but PM mass has some similar values. However, in diesel vehicles with DPF system, PM mass and particle number concentrations were greatly influenced by PM regeneration. Particle emissions in light-duty vehicles emitted about 90% at the ECE15 cycle in NEDC test mode, regardless of vehicle fuel type. Particle emissions at the early cold condition of engine were highly emitted in the test mode.     

Effect of radial interference on torque capacity of press- and shrink-fit gears

Some gears in an automobile transmission have to be mounted by being press-fitted on a shaft instead of splines. The torque capacity of the press-fitted gear will be proportional to the radial interference. The excessive interference, however, will increase the gear radial deformation. In this paper, the press- and shrink-fit and the subsequent torque capacity test were investigated by finite element analysis, theoretically and experimentally. The static and dynamic coefficient of friction were determined.     

Power control strategy for preventing thermal failure of passively cooled automotive battery packs

Safety mechanism is required for an automotive battery pack to prevent thermal failure which could lead to catastrophic events. Passively cooled battery packs can prevent thermal failure by conducting adaptive control of battery power without any external cooling device. The key to this power control is how to secure battery safety while minimizing energy loss. This paper proposes a novel, adaptive power control strategy for automotive passive-cooling battery packs. Four different cases with electrochemical battery model are simulated and compared to each other according to a city driving profile. Driving simulation result confirmed that the present power control algorithm is an effective solution for preventing thermal failure along with improving energy efficiency of automotive battery packs.     

二灰碎石基层强度的正交试验研究

通过正交试验研究二灰碎石各种材料用量（二灰内比、碎石比例和级配、水泥掺量等）与二灰碎石基层强度的关系,旨在从力学角度得到抗裂性能较佳的半刚性材料.结果表明,水泥掺量是影响二灰碎石早期强度的主要因素,其次是二灰内比.另外,适当增加碎石比例和粗集料含量,可以提高强度和减少收缩裂缝.     

Aeronumeric optimal design of a wing-in-ground-effect craft

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.     

Comparison between a reanalyzed product by 3-dimensional variational assimilation technique and observations in the Ulleung Basin of the East/Japan Sea

Reanalyzed products from a MOM3-based East Sea Regional Ocean Model with a 3-dimentional variational data assimilation module (DA-ESROM), have been compared with the observed hydrographic and current datasets in the Ulleung Basin (UB) of the East/Japan Sea (EJS). Satellite-borne sea surface temperature and sea surface height data, and in-situ temperature profiles have been assimilated into the DA-ESROM. The performance of the DA-ESROM appears to be efficient enough to be used in an operational ocean forecast system.Comparing with the results from Mitchell et al. [Mitchell, D. A., Watts, D. R., Wimbush, M., Teague, W.J., Tracey, K. L., Book, J. W., Chang, K.-I., Suk, M.-S., Yoon, J.-H., 2005a. Upper circulation patterns in the Ulleung Basin. Deep-Sea Res. II, 52, 1617-1638.], the DA-ESROM fairly well simulates the high variability of the Ulleung Warm Eddy and Dok Cold Eddy as well as the branching of the Tsushima Warm Current in the UB. The overall root-mean-square error between 100 m temperature field reproduced by the DA-ESROM and the observed 100-dbar temperature field is 2.1 °C, and the spatially averaged grid-to-grid correlation between the two temperature fields is high with a mean value of 0.79 for the inter-comparison period.The DA-ESROM reproduces the development of strong southward North Korean Cold Current (NKCC) in summer consistent with the observational results, which is thought to be an improvement of the previous numerical models in the EJS. The reanalyzed products show that the NKCC is about 35 km wide, and flows southward along the Korean coast from spring to summer with maximum monthly mean volume transport of about 0.8 Sv in August–September.     

Calibration of a transit route choice model using revealed population data of smartcard in a multimodal transit network

Transportation - One of the major objectives of this study is to provide more realistic and accurate results related to transit passenger’s route choice behavior by using population data of...     

Use of 3D compartment model for simplified full ship FE model. Part I: construction of FE model

Classification societies cannot cover the torsional strength assessment with simple empirical formula as the size of a containership increases drastically over 10 000 TEU in recent years. Torsional strength of a container ship is very difficult to estimate with an analytical method due to its alternatively varying cross sections, i. e. an open and a closed section. This article proposes an approach to construct a simplified FE model using a 3D compartment model available from the beginning of ship design process. The model is cut to pieces of lots of small pieces of lines by a set of transverse, longitudinal and horizontal planes. Two algorithms are developed for mesh generation of internal structures; one for assembling the broken lines into closed loops and the other for automatically generating mesh from the loops. Another algorithm is proposed to generate mesh for outer hull using outermost nodes of the FE model built for internal members. The validity of the simplified model is discussed along with a beam theory based approach in J Mar Sci Technol (2008)