Emission characteristics of white smoke or soluble organic fraction (SOF) and black smoke or dry soot from diesel engine were studied by means of mini-dilution tunnel method and Soxhlet extraction method. Further, the contribution of lubricating oil and that of presoot ascribed to condensed hydrocarbon droplet to SOF emission were discussed. The influences of intake air temperature and humidity on SOF and dry soot emission were also studied.
It is shown that the characteristics of SOF and dry soot emission are well clarified against the CO₂ concentration considered to relate with the combustion temperature and O₂ concentration. The SOF emission per unit fuel consumed (SOF emission ratio) is high in the case of low CO₂ concentration region or light load because of the high presoot emission ratio in this region. The ratio of presoot to SOF is about 70% when the engine is in idling. On the other hand, lubricating oil emission ratio is almost constant over a wide range of load. So, in the case of heavy load; low presoot emission region; the ratio of lubricating oil to SOF becomes high.
The higher the intake air temperature, the lower is the SOF emission at the light load due to the decrease in presoot emission, while the dry soot emission is not varied. To raise the intake air humidity decreases not only the SOF emission, but also the dry soot emission, since the OH radical increases in the combustion process.

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The engine damping ratios obtained by the experiments for both high-speed and low-speed diesel engines have been analyzed by using the non-dimensional damping functions defined in the previous paper. The obtained results are as follows:
1) For high-speed diesel engines, friction damping is dominant in engine damping and for low-speed diesel engines, it is comparable to hysteresis damping.
2) The non-dimensional function φ₁ (c_r, D) for high-speed diesel engines is approximately expressed by the following equation.
φ₁ (c_r, D) =0.105R^-2.8 (1.5<R<4)
where, R ; ratio of inertia moment of flywheel I_F to the sum of inertia moments of each cylinder mass I_E . The above equation means that the value of φ₁ (c_r, D) decreases exponentially with increase of natural frequency ω_n.
3) The value of φ₁ (c_r, D) for low-speed diesel engines is very small in comparison with that in high-speed diesel engines, and changes only slightly in accordance with the variation of mass ratio R.
4) The value of ψ₂ (n, p) is almost independent of mass ratio R. As the values of damping ratio due to hysteresis damping, which have been obtained by the experiments for both high-speed and low-speed diesel engines, are approximately 0.002, it can be said that damping ratio due to hysteresis damping ζ_h is nearly constant. This fact confirms the results of the analysis carried out in the previous paper.

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Statistical Energy Analysis (SEA) is applied to analyze structure-borne sound transmission in complex structures.
The system equation describing the energy flow in the structure is derived by the network formulation, and for saving the computational time, approximated formulae for SEA parameters are found.
Measured and calculated results are fairly good agreed for 3D-plate structures, including a scale model of ship structure.
Furthermore, the acousto-structural coupling problem is investigated, experimentally and theoretically, for both cases without and with additional absorbing treatment. From results, the measures for reducing the response in the receiving element and the effect of the treatment are shown.

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From the point of view of energy saving, the shipping project is to be the kinetic energy planning, because the kinetic energy is the final using energy in shipping. And it is very important to consider ship's speed for evaluation of energy in shipping.
Necessary new definitions for this evaluation method are Load Ratio of Total System, Main Fuel Cost Index, Total Cost Consumption Ratio and so on. The purpose of this analysis is to obtain the relations between ship's speed and total cost consumption.

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The fish oil (pollock) is the residual fishing product of the factory trawler in North Pacific Ocean.
For three years, the combustion tests of fish oil were carried out in the auxiliary marine boiler of factory trawler. The results obtained are that the combustion characteristics of fish oil are almost the same as those of petroleum fuels. Then the authors examined to use the fish oil as the fuels of main diesel engine.
In this report, the results of combustion test are described in the case of using the blended fuels (Fish oil/A-Heavy oil) in main diesel engine of ZUIYO-Maru No. 2.
As the results of the experiment, it is made clear that such blended fuels can be actually applicable for the diesel engine fuels without any trouble.

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