Search

The headway distance between vehicles in a platoon is difficult to measure unless the vehicles are equipped with costly equipment such as laser or radar sensors, or an image processing system. This paper proposes an alternate approach to estimating headway distance indirectly from measurable variables such as the acceleration rate and velocity of selected vehicles in the platoon. Assuming a six-vehicle platoon, a particle filter (PF) and an unscented Kalman filter (UKF) are applied in order to estimate the headway of each vehicle based on the measurement variables of three (or all) vehicles in the platoon. The state-space models of the PF and the UKF are given by the conservation equation of headway and the conventional car-following model. To evaluate the PF and UKF performance, two scenarios were prepared: one assumed that prior knowledge of a model parameter differed from what was actually observed as posterior information, the other was a situation where a platoon vehicle slowed down unexpectedly during the car-following process. In both situations, the state-space model itself was unable to describe the dynamics of headway distance precisely, and the PF and the UKF were applied to minimize the headway distance errors caused by the incorrect model parameter and the unexpected vehicle slowdown. Numerical analysis demonstrated that both the PF and UKF were successful in estimating the headway distance, even when the car-following model did not express the true car-following phenomena. We also determined that, if all vehicles are equipped as probe cars, and thus capable of measuring the acceleration rate and velocity, the PF is superior to UKF when estimating the headway distance precisely. However, UKF is more stable than the PF when measurements are not taken from all vehicles, especially when a vehicle in the platoon unexpectedly slows downs during the car-following process.

Rear-end collisions occasionally cause severe multiple-collision accidents, especially in high-density and high-speed traffic. Avoiding the rear-end collisions is one of the critical issues since this type of collision has been the most significant factor among all types of traffic accident for many years. This research aims to develop a driver assistance system that informs the inferred intention of preceding car's deceleration behavior to the following vehicle through an interface based on a wind shield display (W SD). Assuming four vehicles forming a longitudinal platoon, a system was developed in which the deceleration intent of the 3rd vehicle is inferred and informed to the 4th vehicle driver by the WSD. A driving simulator (DS) experiment was carried out to evaluate the performance including the collision risk of the 4th vehicle with and without the system. A series of the experiments showed that the proposed system was significantly effective to mitigate the collision risk even under emergency deceleration scenarios.

This study examines the use of a humanoid robot for not only entertainment but also industrial tasks in a human-occupied environment. An impact task model based on input shaping control of a robot hand equipped with a flexible rubber stick (RS) is discussed and its efficacy is demonstrated. To maintain safety, limited space and a low-power servo motor are considered. The input shaping amplifies necessary vibration while reducing unnecessary vibration. The humanoid robot performs the impact task with high accuracy using the flexible RS and also realizes efficient motion via a double arm. The proposed approach has potential for both industrial and entertainment applications of a humanoid robot in a human-occupied environment.

It is very suitable to select the polymer materials for the housings of surge arresters (SAs), because the polymer materials are generally soft and light weight. Therefore, many kinds of polymer-housed SAs using various polymer materials have been developed, and expanding into many countries. Considering these backgrounds, the JEC technical report (JEC-TR) 23002-2008; polymer-housed surge arrester(1) has been established based on the existent relevant standards of arresters, such as JEC-2371-2003; Insulator-housed surge arresters(2) and IEC 60099-4 Edition 2.2, Metal-oxide surge arresters (MOSAs) without gaps for a.c. systems(3) in order to introduce the technology and provide a common guide for testing of polymer-housed SAs.According as the JEC-TR, the various new applications of the polymer-housed SAs, which are caused by superior advantages such as compact, light weight, safe failure mode, anti-seismic performance, anti-pollution performance and cost efficiency design, have been realized recently in Japan. Therefore, this paper gives specific consideration on the superior performance of the polymer-housed SAs and the evaluation methods of the polymer-housed SAs, because there are some issues in the existent standards to be solved.

Reaction behavior of a packed bed consisting of reagent pellets A or iron ore mini pellets B and coal composite iron ore hot briquettes was examined under the blast furnace simulated conditions until 1200°C. As a result, it was found that reducibility of the mixed bed is governed by reducibility of pellets, whereas gasification of briquettes in the mixed bed is hardly governed by it. However, promotion effects for reduction and gasification of the mixed beds were recognized for both pellets around 1050°C, where abnormal swelling of the easier reduced pellet A occurred remarkably with fine fibrous irons, showing a noticeable pressure drop through the bed. It was suggested that this swelling would be caused by gaseous sulfur derived from coal char in the briquettes. The mixed beds provided larger final shrinkage of the beds than the individual beds probably due to increment of the coupling reactions between reduction and gasification. It was concluded that reducibility of the pellet could influence not only the reducibility of the mixed bed but also the overall reaction behavior such as gas permeability and softening.

For iron making processes which need decreasing CO2 exhaust, coal composite iron ore hot briquette (CCB) is promising. This agglomerate contains coal with iron ore by utilizing the thermal plasticity of coal, where, carbonaceous material and iron ore are closely adjoined at the micro level, and which enables reactions to proceed from lower temperatures and finish earlier.In this study, we assumed mixed charging of CCB in ore bed aiming at improvements of permeability and gas utilization and performed high temperature reaction tests under load simulating blast furnace conditions using mixed samples consisted of iron ore mini pellet and briquette.As a result, gasification and reduction in mixed bed were accelerated around 910°C to 1000°C. This reaction acceleration was presumed to derive from mutual acceleration between gasification in briquette and indirect reduction in pellet. However, if the residual carbon in briquette is consumed completely by gasification, reduction is possibly delayed through the deterioration of permeability by sintering of pellet and briquette.It was also found that increase of reduction gas flow rate prevented the residual carbon in briquette from being consumed and accelerated reduction by sustaining the role of briquette as a spacer. And it was found that lowering thermal reserve zone temperature aggravated reducibility of pellet and delayed reduction of mixed bed. Moreover, it was found that shrinkage behavior of the bed had strong relation to amount of residual carbon in briquette and reduction behavior of pellet.

Gapless Metal (Zinc) Oxide Surge Arresters for a.c. systems contribute to the insulation co-ordination based on the suppression of lightning surges and switching surges. These gapless metal oxide surge arresters using ZnO elements are effective to HVDC systems. This paper describes basic characteristics of ZnO (zinc oxide) elements for d.c. systems and applications of gapless surge arresters to HVDC 125kV frequency converters, HVDC 250kV, upgrade HVDC 500kV converter stations, and HVDC 500kV cables of Japan through the experience of developments and applications of gapless metal oxide surge arresters.

This paper numerically attempted to evaluate characteristics of vehicle-platooning safety in relation to vehicle reaction time and initial spacing. An empirical car-following simulations of seven passenger cars was employed to evaluate safety level of platooned vehicle at approximately 55-60km/h speed with 0.4-0.5G deceleration of the most-front vehicle in the platoon. Numerous simulation trials with varying delay time and initial spading found that there are some car-following situations where safety of vehicle platooning suddenly and sensitively deteriorates even with tiny changes of vehicle reaction time and initial spacing. This situation occurred at normal driving situations where we frequently observe in a real-world traffic.

Pure iron and Fe-0.6mass%P alloy were sintered at various temperatures from 1273K to 1623K. Magnetic properties, i,e., magnetic induction at 800 A/m (B8), maximum permeability (μm) and coresive force (Hc) of these alloys were measured using Cioffi type fluxmeter. Then the microstructures of those alloys were investigated using an optical microscope and an EMPA. Sintered density and the magnetic properties of the pure iron are almost constant in the sintering temperature range.On the contrary, those of Fe-0.6mass%P are improved highly with elevating sintering temperature and shows B8=1.35T, μm=8mH/m and Hc=96AT/m at the sintering temperature 1623K. In the Fe-0.6mass%P sintered alloy, P atoms diffuse into the pure iron with an increase in sintering temperature, resulting in forming of the α phase. This densificates the alloy by α phase sintering and then changes pore shape from irregular to spherical. The magnetic properties of Fe-0.6mass%P sintered alloy are improved by mainly densification with spheroidization of the pores.

This study evaluated the effects of adaptive cruise control (ACC) on traffic flow using a microscopic traffic simulation on an actual freeway corridor, where traffic congestion was observed due to a traffic accident. Four types of ACCs were evaluated to determine their effect on travel time reduction given the low percentage of ACC equipped vehicles. A small numerical example showed that travel times could be significantly reduced only when the ACC is activated for almost all speed ranges and at least 20% of the vehicles are equipped with ACCs.

Traffic information from probe vehicles has great potential for improving the estimation accuracy of traffic situations, especially where no traffic detector is installed. A method for dealing with probe data along with conventional detector data is proposed in this paper. The probe data was integrated into the observation equation of the Kalman filter, in which state equations are represented by a macroscopic traffic flow model. The method was tested under several types of traffic conditions based on hypothetical data, giving considerably improved estimation results compared to those estimated without probe data. The effect of the percentage of probe vehicle deployment in a road network was also quantitatively assessed.

This paper applies a particle filter (PF) and a dual particle filter (DPF) for estimating the headway distance of vehicles traveling in a longitudinal platoon. Assuming that prior knowledge on the model parameter is different from what is observed in a real car-following, PF attempts to estimate the headway by measuring the acceleration rate and velocity of probe cars installed in the platoon. In addition, DPF is proposed to improve the accuracy by estimating the headway as well as the model parameters simultaneously within a single process. Numerical analyses were carried out to evaluate the performance of PF and DPF in two scenarios with six-vehicle platoon and different installation of probe cars. It was found that PF and DPF perform very well if all traveling vehicles in the platoon measure the acceleration rate and velocity. However, the effect of dual filtering process in DPF is not very significant to improve the estimation accuracy because the model parameters are not corrected appropriately by the dual filtering process.

The objective of this study is to clarify the grain growth behaviors of zinc-oxide varistor ceramics with Bi2O3 and TiO2 additions. Zinc-oxide based ceramics have been widely used as transient surge suppressors for protecting electric equipments, because of their highly nonlinear voltage (V)-current (I) characteristics and excellent surge absorption capability. The nonohmic properties of these ceramics are highly affected by characteristics of the microstructures, such as ZnO grain size. A ZnO-6mass% Bi2O3-0.55mass% TiO2 ceramic has been selected for investigating the ZnO grain growth behavior. The experimental results show that the samples consisted of equiaxed ZnO grains and a second phases with the Bi2O3 and spinel crystal structure. It also indicated that the grain growth behavior could be observed to follow a time law for grain size ω of the form ω=κ⋅tn, where t is time and n is a kinetic exponent. The kinetic exponent for ZnO grain growth has been determined to be 1/2 for temperatures below 1303K, but 1/5 above 1379K. A convenient computer-aided system was developed for analyzing the grain growth behavior of sintered materials. It simulated the effects of heating rate and cooling rate on the ZnO grain growth in the ZnO-6mass% Bi2O3-0.55mass% TiO2 ceramic during the sintering process. As a result, it was clarified that the effect of heating rate on the ZnO grain growth was not neglected in comparison with the cooling rate in the range of practical use.

In this study, an applicability of microscopic shockwave (μSW) theory is evaluated whether it is efficient in assessing the risk of rear-end collision in vehicle platoon. Two different types of μSW behavior are proposed for the evaluation; one is the car-following that shows a higher risk, whereas the other is a low-risk vehicle platooning. The numerical analysis attempts to evaluate whether the conventional risk evaluation approaches are able to distinguish those two cases; high and low risk platooning based on the proposed μSW technique. The statistical analysis showed that the behavior of μSW is capable of assessing the risk of rear-end collision of platooning vehicles.

The Signal Recognition Enhancement System or SRES is one of practical ITS which is expected to avoid rear-end collisions at a signalized intersection by providing signal information to a vehicle and/or a driver before reaching an intersection. This system is also expected to suppress the unnecessary fuel consumption and reduce CO 2 emissions. This paper aims to evaluate the impact of the SRES which will be installed at signalized intersections. We develop the micro traffic simulation model which includes the behavior of a driver with/without SRES to estimate the impact SRES on the traffic flow around an intersection. We employed the time integral of difference of space distance and stopping distance or TIDSS as the indicator for measurement of safety, while we employed the equations to calculate fuel consumption and CO 2 based on an average velocity. Numerical simulation showed that SRES might help to reduce collision, fuel consumption and CO 2 emissions at signalized intersections.