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Tie Li, Masaru Suzuki, Toshio Shudo, Hideyuki Ogawa
2008 Volume 29 Issue 4 Pages
463-470
Published: 2008
Released on J-STAGE: August 27, 2009
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Simultaneous reduction of smoke and NOx from diesel engines with ultra-high EGR (exhaust gas recirculation) is attributed to the lowered combustion temperature and the improved fuel-air mixing by the extended ignition delay. To independently analyze the two effects,the effects of various cetane number fuels on ultra-high EGR low temperature diesel combustion are systematically examined. Although smokeless and ultra-low NOx combustion can be realized regardless of mixture homogeneity as long as the temperature is sufficiently low, fuel-air mixing is vital for an acceptable combustion efficiency. Finally, the operating range of smokeless and ultra-low NOx diesel combustion with low compression ratio and low cetane number fuels are discussed.
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-Evaluation of Direct Heat Loss to Cylinder Liner Wall-
Takeshi Sugihara, Yasuko Suzuki, Masahiko Emi, Kenjiro Shimano, Yoshit ...
2008 Volume 29 Issue 4 Pages
471-478
Published: 2008
Released on J-STAGE: August 27, 2009
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Direct heat loss is defined as heat flowing directly from the combustion gas to the combustion chamber walls. The authors' group has investigated the direct heat loss at combustion chamber walls by means of heat transfer analysis using measured instantaneous wall surface temperature. This study focuses on the cylinder liner of a D.I. diesel engine. The cylinder liner wall receives heat from various objects such as the combustion gas, the piston and the piston rings. Incoming heat from the gas to the wall is separated so that the state of the direct heat loss and the heat loss ratio can be evaluated. As a result, this study shows that the heat loss ratio of the cylinder liner occupies approximately 4% of the heat of supplied fuel and also approximately 20% of the total heat loss through all combustion chamber walls other than the valves.
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-Comparison of a Toroidal CVT and a Belt CVT-
Koji Ishikawa, Eiji Inoue, Takashi Imanishi
2008 Volume 29 Issue 4 Pages
479-483
Published: 2008
Released on J-STAGE: August 27, 2009
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The number of vehicles sold in Japan that are equipped with continuously variable transmissions (CVTs) has continually increased in recent years. The efficiency of an automotive transmission is an important factor in improving fuel economy and reducing CO
2 emissions. Therefore, the authors took note of the efficiency of a traction-drive CVT and a belt-drive CVT. Based on efficiency measurements for various driving conditions; we analyzed the different characteristics for the differing structures of both traction-drive and belt-drive CVTs.
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Masanori Yamazaki, Yoshiaki Kato, Tsunamitsu Nakahara, Toshihiko Ichih ...
2008 Volume 29 Issue 4 Pages
485-492
Published: 2008
Released on J-STAGE: August 27, 2009
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In this study, we clarified the parameters of surface roughness that have a high correlation with the friction coefficient and made clear the factors producing a high friction coefficient by measuring the mechanical characteristics of the boundary lubrication film. We verified that improving the friction coefficient between the belt elements and pulleys of a metal belt CVT by 20% over the current level can improve vehicle fuel economy by 2%. This can be achieved by combining control of the pulley surface properties with a high-friction CVT fluid.
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Yuji Mihara, Tomomi Matsuzaki, Tsuneo Someya
2008 Volume 29 Issue 4 Pages
493-500
Published: 2008
Released on J-STAGE: August 27, 2009
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In order to understand the stress distribution in the piston pin-boss under an engine operating condition, a new thin-film sensor was developed to measure the oil-film pressure in pin-bosses. The sensor has a φ0.45 mm sensing part and 7 μm in total thickness was deposited by sputtering on the piston pin surface. This kind of sensor has already succeeded in measuring the oil-film pressure distribution in engine bearings. However, the result is affected by the high temperature in the piston pin, and especially by the temperature dependence of sensor sensitivity. To obtain stable characteristics, nitride films were applied as protection and insulation films. This paper presents the new sensor structure and measurement results.
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Naoya Ishikawa, Naoki Shimazaki, Kazuaki Kudou
2008 Volume 29 Issue 4 Pages
501-508
Published: 2008
Released on J-STAGE: August 27, 2009
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This paper reports a low NOx and low smoke combustion concept for a DI diesel engine and an investigation into its combustion characteristics. In this concept of combustion, using a high EGR rate combining with head swirl, combustion chamber design and optimal injection timing, the combustion process occurred under a moderate reaction rate with greatly improved fuel mixing. As a result, both NOx and smoke emissions were reduced considerably.
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Shuichi Araki, Shigenori Kinoshita, Masakazu Sasaki, Hiromasa Matsui, ...
2008 Volume 29 Issue 4 Pages
509-514
Published: 2008
Released on J-STAGE: August 27, 2009
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The application of newly developed high performance electric double layer capacitors (EDLCs) is currently expanding to hybrid electric vehicles (HEVs) and other power systems. However, the lack of optimal performance measurement methods that correspond to the increasingly complicated characteristics of new EDLCs prevents easy application engineering. Therefore various experimental and theoretical analyses for new high performance EDLCs were performed. As a result, optimal testing methods for the measurement and evaluation of new EDLCs were successfully established to reveal their capacitance, available energy capacity, internal resistance, charge/discharge energy efficiency, and so on.
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Atsushi Masuda, Kunitoshi Shimizu, Shigeaki Shimojima, Takeshi Ichikaw ...
2008 Volume 29 Issue 4 Pages
515-519
Published: 2008
Released on J-STAGE: August 27, 2009
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A large transit hybrid bus equipped with an inductive recharging system was developed in a Ministry of Land, Infrastructure, Transport and Tourism (MLIT) project. The hybrid bus passed through motor vehicle inspection and registration, and is still under continuous examination. We evaluated the fuel and electric economy of the hybrid bus in city driving and the efficiency of the inductive recharging system during charging to the battery. This paper reports the test results of the hybrid bus.
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Takaomi Makino, Toru Mogi, Yoshikazu Tsuruoka, Mitsuo Yuki
2008 Volume 29 Issue 4 Pages
521-526
Published: 2008
Released on J-STAGE: August 27, 2009
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In order to represent the real world faithfully, computer simulations have become increasingly more complex in recent years, which has tended to lengthen the computational time involved. In simulation-based robust design, the necessity of considering the variation of each parameter greatly increases the number of specifications that are calculated. In practical terms, that makes it impossible to examine robust designs thoroughly in some cases. With the aim of overcoming this problem, this study examined a method for executing a robust design efficiently even when simulations requiring a long computational time are used. The proposed method was applied to optimize the shape of an automotive engine exhaust port. This paper describes the proposed method for executing simulation-based robust designs efficiently and presents the results of its application to the exhaust port shape.
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Tadashi Nakagawa, Masakatsu Tsubouchi, Mitsuro Suzuki
2008 Volume 29 Issue 4 Pages
527-532
Published: 2008
Released on J-STAGE: August 27, 2009
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This paper introduces an automotive exhaust heat recirculation system. This system was developed to improve fuel economy after cold starts in the winter. The warm-up speed of the engine and heater performance can be improved by recovering exhaust heat from exhaust gas to the engine coolant. As a result, the actual fuel economy is improved due to earlier engine stops in hybrid vehicles.
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Noboru Kubo, Sou Kitajima, Tatsuya Kobayashi, Akiomi Shiina, Masando E ...
2008 Volume 29 Issue 4 Pages
561-566
Published: 2008
Released on J-STAGE: August 27, 2009
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This article shows the characteristics of accidents and near-accidents of 200 taxicabs in Tokyo. The authors' group collected more than 100,000 records and observed various characteristics of taxicab driving such as scooping other cars, violating traffic regulations, and so forth. The group also noticed several main points for avoiding traffic accidents such as an appropriate speed from the reaction time, the inductivity of near-accidents with bicycles, and the like.
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Teiyuu Kimura, Kenji Ishida, Noriyuki Ozaki
2008 Volume 29 Issue 4 Pages
567-574
Published: 2008
Released on J-STAGE: August 27, 2009
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This research examined the feasibility of detecting sleepiness using expression features. About seven distances between facial feature points were set up as expression features based on the movement of expression muscles. The facial feature points were detected by pattern recognition using an Active Appearance Model (AAM). A sleeping experiment using a driving simulation task was conducted to measure the correlation between sleepiness levels and expression features, and then determine the feasibility of sleepiness detection.
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Yohei Michitsuji, Daisuke Mezaki, Masao Nagai, Minoru Kamata, Motoki S ...
2008 Volume 29 Issue 4 Pages
575-580
Published: 2008
Released on J-STAGE: August 27, 2009
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During a yellow light at a signalized intersection, drivers occasionally fall into the dilemma whether to pass through the intersection or to stop at the stop-line. As the result of an aggressive pass or a sudden stop, rear-end collisions and head-on accidents may occur. In this paper, drive recorder equipped vehicles provide many incident data that occurred during yellow lights, and actual dangerous zone is extracted. Because the zone is one of the targets for accident prevention, the obtained insights are useful in considering measures for enhancing safety such as the dilemma avoidance signal control and other related ITS technologies.
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Hiroshi Iguchi, Shingo Komura, Takashi Shirasu
2008 Volume 29 Issue 4 Pages
581-588
Published: 2008
Released on J-STAGE: August 27, 2009
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The vibration transfer characteristics of the body and seats are becoming more important as automakers strive to satisfy demands for improved ride quality. This study shows that the vibration of a virtual rigid body can be calculated by expressing the vibration magnitude of each part in a vehicle shaker test as the product of the suspension transmission force and inertance. Consequently this analytical method is effective for quantifying the vibration amplification rate caused by the body and other elements.
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Nobuyo Kasuga, Toichi Sawada, Yasuhiro Daisho
2008 Volume 29 Issue 4 Pages
589-596
Published: 2008
Released on J-STAGE: August 27, 2009
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A study was conducted to clarify the environmental factors causing drink-driving in Japan. A hundred and seventy three drivers were asked to fill out a questionnaire about their experiences of drink-driving over the past two years. The questions included the driver's demographic characteristics, frequencies of drinking alcohol and drink-driving, and the attitude of surrounding people to the possibility of drink-driving. A chi-square test was used to clarify factors inducing drink-driving. The results show that drinking habits are associated with drink-driving, and that low recognition of the danger of drink-driving is a factor resulting in drink-driving. Education for drivers is essential to manage drinking habits and to raise recognition of the danger of drink-driving.
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-Pedestrian Model-
Hiroko Mori, Tetsuo Kurahashi, Tatsuya Iwase, Takashi Machida, Hironob ...
2008 Volume 29 Issue 4 Pages
597-603
Published: 2008
Released on J-STAGE: August 27, 2009
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We propose a newly pedestrian model for evaluating vehicle-pedestrian accidents using STREET we have been developing. The pedestrian model can simulate pedestrian-to-vehicle interactions by making pedestrians and drivers behave in their surroundings based on their cognition and decisions. It reproduces the behavior of pedestrians by setting up action rules governing combinations of positions of pedestrians, their modes of action, and cognition targets. Finally, we have validated the pedestrian model with an example of simulating basic operations regarding the ignoring of signals and vehicle-to-pedestrian right-turning gaps, thereby confirming that the example exhibits a tendency that closely corresponds to the actual measurements.
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Masanori Motoki, Hiroshi Hashimoto, Kimio Hayano, Tamotsu Hirao, Shinj ...
2008 Volume 29 Issue 4 Pages
605-610
Published: 2008
Released on J-STAGE: August 27, 2009
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In Japan, it has been mandatory to equip the driver's seat of passenger cars with the safety belt reminder system (SBR) for new models since September 2005 and for continuous product models from September 2008. This study examined the effects of SBR by the following two approaches.
(1) Survey on the ratio of safety belt use with/without SBR : It was confirmed that SBR effectively increases usage of the driver's safety belt (90.1% without SBR → 97.3% with SBR).
(2) Interview of drivers of SBR-equipped passenger cars : How and when SBR is activated were clarified, and both positive and negative evaluations of SBR functions were collected.
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Motoyuki Akamatsu, Masaaki Onuki
2008 Volume 29 Issue 4 Pages
611-618
Published: 2008
Released on J-STAGE: August 27, 2009
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A driving simulator enables driving a vehicle in a simulated environment, and various technologies have been applied to make this environment realistic This article describes the recently developed technologies for reproducing a road environment, including scenery along the road and geometric road structures, vehicle vibration caused by road surface conditions and gaps in road segments, and the auditory environment in the vehicle cabin.
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Makoto Kihira
2008 Volume 29 Issue 4 Pages
619-626
Published: 2008
Released on J-STAGE: August 27, 2009
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Drivers often encounter situations requiring immediate and error-free decision for their subsequent tactics. This means that continuous observation of the surroundings is needed to confirm safety during driving. In estimating driver aptitude, therefore, competence of handling multiple sources of information and integrating substantial amounts of information according to real driving situations should be considered. This study developed a driving simulator for evaluating driver performance in checking mirrors, with scenes and operations similar to those found in a real car. Through an experiment contrasting older and younger adults, this driving simulator revealed considerable performance deterioration among older adults.
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Goro Obinata, Tasuku Usui, Naoki Shibata
2008 Volume 29 Issue 4 Pages
627-632
Published: 2008
Released on J-STAGE: August 27, 2009
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This study proposes a method to evaluate quantitatively the influence of driver distraction caused by information processing demand in real time. It focuses on VOR (vestibulo-ocular reflex), or involuntary eye movement. First, the method identifies the dynamics of VOR without information processing demand, and then it compares measured VOR output with identified model output in real time. This model-based method makes it possible to evaluate the influence of distraction on VOR. This study experimentally confirmed that the proposed method is useful and practical for evaluating driver distraction in real time.
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