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A new index U* for evaluating load path dispersion is proposed, using a structural load path analysis method based on the concept of U*, which expresses the connection strength between a load point and an arbitrary point within the structure. U* enables the evaluation of the load path dispersion within the structure by statistical means such as histograms and standard deviations. Different loading conditions are applied to a body structure, and the similarity of the U* distributions is evaluated using the direction cosine and U* 2-dimensional correlation diagrams. It is shown as a result that body structures can be macroscopically grasped by using the U* distribution rather than using the stress distribution. In addition, as an example, the U* distribution of torsion loading condition is shown to comprehensively include characteristics of the U* distribution of other loading conditions.

This study computationally investigates the combined effects of EGR and boost pressure on HCCI autoignition using iso-octane, PRF50 and n-heptane. The computations were conducted using the single-zone model of CHEMKIN included in CHEMKIN-PRO with detailed chemical-kinetics mechanisms for iso-octane, PRF and n-heptane from Lawrence Livermore National Laboratory (LLNL). To better reproduce the state of EGR addition in real engine, the EGR composition is determined after several combustion cycles under the constant amount of fuel. All data points were acquired with a CA50 of 5°CA aTDC by adjusting initial temperature to remove the effect of combustion phasing, which can influence on HCCI autoignition from any effect of the EGR and boost pressure themselves. The results show that EGR increases the burn duration and reduces the maximum pressure-rise rate with lower peak of maximum heat-release rates for all fuels even for a boost pressure, which accelerates a HCCI autoignition propensity.

Prediction of the discharge path behavior between electrodes on a spark plug is important for efficient energy use in internal combustion engines, especially in lean combustion. In this paper, we propose a numerical model for the prediction of the spark path behaviors based on the coupling of a flow field, a Lagrangian particle model, and an equivalent circuit model. A turbulent flow around cylinders imitating electrodes is solved using a direct numerical simulation, in which Lagrangian particles along the spark path are tracked. Electric current and inter-electrode voltage are computed based on the energy conversion rate from the circuit to the mixture gas. As a result, a discharge path is reproduced with Lagrangian tracking particles virtually aligned between the cylinders. The spark path has a complicated structure along the spanwise direction due to the complex three-dimensional vortical structure of the cylinder wake.

In recent years, the number of reported traffic accidents due to sudden deterioration in driver’s physical condition has been increasing, it is expected to develop a system that prevents accidents even if physical condition suddenly changes while driving, or reduces damage through vehicle body control. For this purpose, it is necessary to detect sudden changes of the driver’s physical condition, and research is being conducted widely. Among them, it is reported that some of such changes may appear in the heartbeat interval. In other words, by acquiring the driver’s heartbeat interval in real time, it may be possible to detect the sudden changes, and reduce traffic accident. Even if a traffic accident occurs, the damage can be reduced by emergency evacuation immediately after detecting sudden changes.

A significant drawback to HCCI engines is the knocking caused by rapid increases in pressure. Such knocking limits the capacity for high-load operation. To solve this problem, thermal stratification in the combustion chamber has been suggested as possible solution. Thermal stratification has the potential to reduce the maximum value of the rate of pressure increase combustion by affecting the local combustion start time and extending the duration of combustion. The purpose of this study was to experimentally obtain fundamental knowledge about the effect of thermal stratification on the HCCI combustion process. Experiments were conducted in a rapid compression machine (RCM) equipped with a quartz window to provide optical access to the combustion chamber. The machine was fueled with DME, n-Butane, n-Heptane and iso-Octane, all of which are currently being investigated as alternative fuels and have different low temperature characteristics.

The Homogeneous Charge Compression Ignition (HCCI) engine is possible to achieve high thermal efficiency and low emissions. One of the main challenges with HCCI engines is structuring the systems to control combustion phasing, crank angle of 50% heat release (CA50), for keeping high thermal efficiency and avoiding an excessive rate of pressure rise which causes knocking, when operating conditions vary. Though some HCCI combustion control systems, for example Variable Valve Timing System and Variable Compression Ratio System, have been suggested, these control systems are complex and heavy. In this study, for the development of a lightweight and small-sized generator HCCI engine fuelled with Dimethyl Ether (DME) which is low-emission and easy to autoignite, a simple HCCI combustion control system is suggested, and the control system is evaluated experimentally.

The purpose of this study was to gain a better understanding of the effects of in-cylinder gas temperature stratification on reducing the pressure-rise rate in HCCI combustion. HCCI combustion was investigated using an optically accessible engine and direct visualization of the combustion chemiluminescence. The engine was fueled with Di-Methyl Ether. Computational work was conducted on the gas compression and expansion strokes in HCCI engine with simple 0-dimensinal multi-zones model. When fuel inhomogeneous charging in experiment, maximum heat release rate decreased. Combustion duration got longer. Maximum pressure-rise rate decreased. Chemiluminescence, of which transition was identified from the side of intake valve to the side of exhaust valve, was observed. It is need for total moderate heat release to get local moderate combustion with not overall but continuous combustion in chamber.

In a previous study, we developed and validated a new driving posture focused on biomechanical loads for physical fatigue reduction in static long-term sitting. In this study, the posture was evaluated in dynamic long-term driving condition by qualitative and quantitative measurements. The results showed physical fatigue of the new posture was halved in comparison with the one of the conventional posture in same car by subjective evaluations. Physiological indices had same tendency with subjective evaluations. From the results, we extracted seven physiological indices as good measures of physical fatigue while driving. Therefore, fatigue reduction of the new posture was qualitatively validated by physiological measurements.

The load path U* analysis is an effective tool for investigating the load paths in body structures. In the present study, a new index U** is introduced to investigate structures under distributed loading. The new parameter U** is a complementary concept of U*. Although the conventional index U* cannot be applied to cases of distributed loading conditions, the new index U** can be applied to those cases. This paper describes the application of a load path U** analysis to improve efficiently the first eigenvalue of the vertical bending mode in a vehicle body structure model. It also explains how target parts for shape optimization are interpreted on the basis of a load path U** analysis when a load is applied to reproduce the first vertical bending mode.

Nitrogen oxides, collectively called NOx, from diesel vehicles are considered to be accumulated by particular area of roadsides, so-called "Hot-spot," and result in harmful influence to pedestrians and residents by roadsides. Japanese regulations over emissions of diesel vehicles have been tightened year by year and adopting regulations, emissions in mode test on chassis dynamometer or engine dynamometer have reduced. In this research, it was investigated the effect of introduce of transient mode test, Japanese JE05 mode, to NOx emission in real world and to roadside NOx pollution by road test using on-board measurement system. As test vehicles, 2 ton diesel vehicle which is adopted for Long Term Regulation (steady-state mode test, Diesel 31 mode test, 1998) and 3 ton diesel vehicle adopted for New Long Term Regulation (transient mode test, Japanese JE05 mode, 2005) with on-board measurement system was used.

Theoretically, homogeneous charge compression engines (HCCI) are able to grant a high thermal efficiency, as well as a low NOx and particulate emissions. This ability is mainly due to the combustion process, which, contrary to both Diesel and Gasoline engine, is homogeneous in time and space within the combustion chamber. But despite these advantages, the engine operating condition is limited by the narrow boundaries of misfire at low load and knocking at high load. For that matter, one of the numerous ways of overcoming knocking is to deliberately create fuel inhomogeneities within the combustion chamber, since it has proved to lengthen combustion duration and to drastically reduce maximum pressure rise rate (PRR). Nevertheless, though the global effects of fuel inhomogeneities on PRR have been studied, we lack information that explains this phenomenon.

In this study, the effects of fuel properties, aromatics content and 90% distillation temperature T90, on flame temperature and soot formation were studied using a rapid compression machine (RCM). Aromatics content and T90 distillation temperature were parameters isolated from influence of each other, and from cetane number. A fuel spray was injected in the RCM combustion chamber by a single nozzle hole. The ignition and combustion processes of diesel spray were observed by a high-speed direct photography. Flame temperature and KL factor (which indicates the soot concentration), were analyzed by the two-color method. The rate of heat release was analyzed from indicated diagrams. The fuels with aromatics content showed higher flame temperature. The fuel with highest T90 distillation temperature showed highest flame temperature.

In this study, effects of nozzle hole diameter and EGR ratio on flame temperature (indication of NO formation) and KL value (indication of soot formation) were investigated. Combustion of a single diesel fuel spray in the cylinder of a rapid compression machine (RCM) was analyzed. Three nozzles with different hole diameter were used corresponding to present, near term and long term heavy duty diesel engine specifications. EGR was simulated through 2%vol. CO2 addition to the inlet air and by increase of in-cylinder surrounding gas temperature. Various types of fuels were used in this. The ignition and combustion processes of diesel fuel spray were observed by a high-speed direct photography and by indicated pressure diagrams. Flame temperature and KL factor were analyzed by a two-color method. With larger nozzle hole diameters there are larger high temperature areas. With smaller nozzle hole diameters there is more soot formed. Introduction of 2% vol.

In the HCCI Engine, inhomogeneity in fuel distribution and temperature in the pre-mixture exists microscopically, and has the possibility of affecting the ignition and combustion process. In this study, the effect of charge inhomogeneity in fuel distribution on the HCCI combustion process was investigated. Two-dimensional images of the chemiluminescence were captured by using a framing camera with an optically accessible engine in order to understand the spatial distribution of the combustion. DME was used as a test fuel. By changing a device for mixing air and fuel in the intake manifold, inhomogeneity in fuel distribution in the pre-mixture was varied. The result shows that luminescence is observed in a very short time in a large part of the combustion chamber under the homogeneous condition, while luminescence appears locally with considerable time differences under the inhomogeneous condition.

The purpose of this research is to get fundamental knowledge and to experimentally understand about combustion characteristics of the fuel mixture. This paper shows the Homogeneous Charge Compression Ignition (HCCI) characteristics of a mixture of n-Heptane and iso-Octane in a rapid compression machine. The experimental matrixes cover the n-Heptane mixing ratios, rn-Heptane, ranging from 0 to 100vol% and the equivalence ratios ranging from 0.1 to 0.6. The experimental study on the effect of mixing fuels focuses on the low temperature oxidation reaction temperatures, TL, the high temperature oxidation reaction temperatures, TH, the low temperature oxidation reaction starting times, tL, the high temperature oxidation reaction starting times, tH, and the degeneration period. The results show that as rn-Heptane decreases, tL and tH become longer and TL and TH increase by 30K. As the equivalence ratio increases, tL becomes longer but tH is not a function of equivalence ratio.

It is necessary to clarify the influence on NOx emissions by driver's operation for analyzing of NOx pollution mechanism at roadside. Simple on-board measurement system for vehicle running condition and actual NOx emissions was developed to evaluate local NOx pollution caused by vehicles. The measurement system was installed in a freight vehicle whose payload is two tons, and actual driving test was conducted to evaluate the effectiveness of the system. The tests on chassis dynamometer including steady state and transient mode indicated enough accuracy to evaluate NOx emissions from a vehicle at local roadsides.

This paper proposes a battery state estimation on a battery management system (BMS) for hybrid electric vehicles (HEVs) and electric vehicles (EVs). It is important to estimate a state of charge (SOC) and parameters of the battery such as a state of health (SOH), internal resistances and dynamics of electrochemical reactions. The BMS can provide information on the driving range of the EVs to the drivers by accurately estimating SOC and SOH. It can also calculate a state of power (SOP) to use the battery safely by accurately estimated SOC, internal resistances and others. For that purpose, this paper proposes the BMS adopted a simultaneous state of charge (SOC) and parameter estimation method using log-normalized unscented Kalman filter (LnUKF). The key idea is a lognormalization of the parameters to improve numerical stability and robustness of the algorithm. The proposed system is verified by a series of simulations using experimental data with EVs.

Knock is a factor hindering enhancement of the thermal efficiency of spark ignition engines, and is an unsteady phenomenon that does not necessarily occur each cycle. In addition, the heat release history of the flame also fluctuates from cycle to cycle, and the auto-ignition process of the unburned mixture (end-gas), compressed by the global increase in pressure due to release of chemical energy, is affected by this fluctuation. Regarding auto-ignition of the end-gas, which can be the origin of knock, this study focused on the fluctuation of the flame heat release pattern, and used a zero-dimensional (0D) detailed chemical reaction calculation in an attempt to analyze and examine the consequence on the end-gas compression and auto-ignition process of changes in the i) start of combustion, ii) combustion duration and iii) center of heat release of the flame.

The HCCI combustion mode poses its own set of narrow engine operating by knocking. In order to solve this, inhomogeneity method of mixture and temperature is suggested. The purpose of this research is to get fundamental knowledge about the effect of thermal stratification on HCCI combustion of n-Heptane/iso-Octane-Air mixture. The temperature stratification is made by buoyancy effect in combustion chamber of RCM. The analysis items are pressure, temperature of in-cylinder gas and combustion duration. In addition, the structure of flames using the two dimensional chemiluminescence's images by a framing camera are analyzed. Under stratification, the LTR starting time and the HTR starting time are advanced than that of homogeneous. Further, the LTR period of homogeneous conditions became shorter than that of the stratified conditions. . With the case of homogeneous condition, the luminosity duration becomes shorter than the case of stratified condition.

CNG/diesel dual-fuel engine is using CNG as a main fuel, and injects diesel only a little as an ignition priming. In this study, remodeling an existing diesel engine into dual-fuel engine that can inject diesel with high pressure by CRDI (Common Rail Direct Injection), and injecting CNG at intake port for premixing. The results show that CNG/diesel dual-fuel engine satisfied coordinate torque and power with conventional diesel engine. And CNG alternation rate is over 89% in all operating ranges of CNG/diesel dual-fuel engine. PM emission is lower 94% than diesel engine, but NOx emission is higher than diesel engine. The output of dual fuel mode is 95% by the diesel mode. At this time, amount of CO₂ and PM are decreased while CO, NOx, and THC are increased. In NEDC mode, exhaust gases except NOx are decreased.