Measurements of atmospheric concentration of NO_x and SO₂ were carried out by using the chemiluminescence method of NO_x and the ultraviolet-fluorescence method of SO₂, and by using the training ship Fukae-maru of Kobe Universtiy of Mercantile Marine in the Sea Areas of Osaka Bay and Seto-inlands Sea.
Measurements results make clear the followings. (1) The exhausts from ships have obvious impacts on NO_x and SO₂ concentration in the narrow water areas and/or in the ports where marine traffic is congested. (2) The atmosphere of the north-west area of Osaka Bay is highly polluted in some weather conditions such that the wind due to scale pressure systems is weak and the land-and-sea breeze is prevailing.

View full abstract

This paper presents an investigation into the effect of exhaust gas recirculation on the particulate and its component emissions in a direct injection diesel engine. A hot EGR was applied to a single-cylinder 3L engine at a constant speed of 900rpm over a wide range of operating condition. EGR was revealed to have an effect of particulate suppression under some condition, and the suppression effect came from the reduction in the SOF component. This EGR effect is considered to be caused by the dilution of the intake gas with the recirculated gas which was suggested by the ignition delay measurement.

View full abstract

The control of soot emission from the diesel engine have been one of the important subjects because the soot plays an important role in relation to air pollution.
The measuring of soot concentration on real time is not well established. Considerable understanding of soot concentration have been achieved by the measurements of mass concentration of soot from diesel engines by means of probe sampling methods (JIS type etc.) . Developments of the optical measuring system, in order to get a more detailed understanding of soot concentration in exhaust tube on real time, come up as an important problem.
The form of soot particles in the exhaust tube seems to be monodispersive and spherical or clusterlike, such as long chain polymer molecules. It assume that the form and number density of soot particles become a state of volume mean diameter.
This system have been made using the laser-light scattering and attenuation techniques by the G. Mie's theory to make clear the diameter and number density of soot particles. A50 (mW) helium-neon laser emitting monochromatic radiation at a wavelength of 632.8 (nm) is used as the light source. An incident light beam from the light source is composite beam of the vertical (i₁) and horizontal (i₂) polarization components.
The diameter of soot particle can be determined from the intensities ratio of both integral scattered light from soot particles.
i is the intensity of the scattered light. It's value is defined as [60°∫40° (i₁+i₂) dθ/140°∫120° (i₁+i₂) dθ], θis the scattring angle. The soot refractive index of m=1.85-I⋅0.475 proposed by Lee and Tien is selected, mass per unit volume of soot is assumed ρ_s=2.0 (g/m³)
The results are as follows. At fuel flow is 0.75 (L_N/min), The volume mean diameter (Ds) of soot particles in the exhaust tube lie between 200 and 230 (nm) . The total mean diameter is about 214 (nm) .
The number density and mass concentration of soot particles are estimated to be about 1.90×10⁶ (particles/cm³) and 0.02 (g/m³), respectively. The mass concentration is no significant difference between the results of optical method and filter system.

View full abstract

Pushing-up and torque slip tests were performed using model propeller boss (AlBC3), tiller boss of steering gear (SC410) and shaft (SF440A) to investigate friction behavior of the keyless tapered surfaces and to find out a clue of countermeasures of torque slip problem. As the results of experiments, (1) The coefficients of friction of propeller including pushing-up and torque slip tests are 0.15-0.20 under dry condition. On the other hand, the coefficients of steering gear in dry fit shows higher than 0.20 due to strong adhesion of similar metals. (2) MoS₂ lubricant and anti-rust agent NP-19at the contact surfaces predominantly decrease friction and easily cause torque slip. (3) The coefficients of friction in elastoplastic deformation of boss is slightly higher than those in elastic one. From the practical aspect, it is proposed that boss is pushed up into shaft nearly to the upper limit of an allowable pushing-up distance in order to prevent an accident of torque slip.

View full abstract

In this paper, the optimal value of reactor ratio a in the high frequency inverter power supply for an electromagnetic propulsion system was examined. The reactor ratio of a influences zero current switching (ZCS) characteristics such as ZCS operation region and conduction loss.
The ZCS is important circuit topology for stable operation of the high frequency inverter. On the basis of the numerical analysis of α in connection with ZCS characteristics, the high frequency power supply was designed. The experiment of the electromagnetic propulsion system in the water tank was performed and evaluated.

View full abstract