The marine large bore 2 stroke diesel engines have their own layout diagram defined by the certain range of mean effective pressure p_me and also of the engine speed n. The customers can select voluntarily any combination of power and speed in this layout diagram as the MCR point of his engine. In relation to the exhaust emission regulation by IMO, it is very important and urgent subject to clarify the NOx emission characteristics of the engines in the layout diagram.
In this paper, the behavior of the maximum gas temperature in cylinder T_max in the layout diagram was analyzed and also the many NOx emission data on the shop trials were investigated. Consequently, the following facts have been clarified.
The NOx emission values on the E3 mode in the IMO Technical Code coincide relatively well with those on 100% load. Therefore the evaluation and analysis of the NOx emission characteristics can be executed by means of the NOx emission values on 100% load.
The value of the degree of explosion p_max/pc correlates closely with T_max, and also T_max correlates closely with the NOx emission values. One of the cause of the relatively large dispersion of the NOx emission values is the scattering of the p_max/pc on the shop trials.
In case of the p_me derating in the layout diagram, if the slope of p_s/p_me to p_me/p_me0 is set to be approx. -0.11, then the value of ps/pme is made to increase along with the decrease of p_me/p_me0 by the matching and the value of T_max is kept to be almost same, subsequently the value of NOx is kept also almost same.

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Mechanisms of nitric oxide formation and emission for a conventional high-speed direct-injection diesel engine have been studied by a stochastic model that takes chemical kinetics into account. In calculations cetene was used as a fuel and its initiation processes were expressed by a one-step global mechanism. Detailed reduced chemical mechanisms were employed for the processes of heat release and NO formation. The calculated NO concentration coincides with a value measured in an exhaust gas within 10%. It is shown that most NO is formed locally at temperatures higher than 2000 K under a range of excess air ratios, 1< λ <3.
The effects of EGR and water addition on reducing NO and soot emission were also discussed. Results show that EGR up to 10% shifts the local excess air ratio from those points where NO is formed intensively to fuel rich regions without almost any temperature drop. Thus, EGR reduces NO emission without sacrificing thermal efficiency. EGR, however, reduces the local oxygen concentration and this causes the increase in soot emission. On the other hand, water addition shifts the local mixing ratio from the NO forming region to lower temperature region without decreasing local oxygen concentration in a fuel rich region. For this reason, water addition for reducing NO emission basically results in a drop in fuel economy but it does not increase soot emission. Furthermore, the effects of CO₂ addition on NO and soot emission were discussed and it is shown that CO₂ addition shifts the local mixture to rich at λ >1 and to lean at λ <1. It suggests that CO₂ addition is able to reduce NO and soot emission without the drop in thermal efficiency.

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Developing techniques to evaluate fuel stability and combustibility is essential to ensure the quality of marine fuel oil.
Experimental research was performed to determine the combustion performance of marine fuel using the thermogravimetry-differential thermal Analysis (TG-DTA) and the fuel droplet combustion method and the fuel ignition Analyzer (FIA-100) .
The results made it possible to distinguish between normal fuel and fuels which caused combustion problems.
Compatibility of fuel oils follows solubility theory. The solubility of asphaltene can be predicted by the Scatchard-Hildebrand equation. This paper describes how to apply the solubility theory to evaluate fuel stability of marine fuel oil.

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This paper refers to the influences of varition factors in respect to NOx emissions from medium speed power generating diesel engines. The level of NOx emission from such an engine is liable to be influenced by airborne moisture and the ignitability of fuels. To clarify the influence of fuel ingnitability among all relevant factors, upon NOx emission, combustion testing was conducted on a single-cylinder engine using fuels of different cetane indexes. On the basis of this testing, the results revealed that at the combustion test for certification of compliance of marine diesel NOx emission, the influence of fuel ingnitability in NOx emission is not negligible.

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This information deals with a computation methods of the least-squares method based on the influence coefficients for multi-plane balancing of flexible rotors. Applying the orthogonalization (QR decomposition) to the normal equation of the least-squares method, a personal computer programs is developed in the simple form on the computation languages and environment of Mathematica or MATLAB. This approach have higher accuracy rather than the conventional influence coefficient method and the normal equation without QR decomposition. It is expected that this personal computer based program is applicable to handy vibration measuring instrument set or hand held-computer.

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The cause of propeller singing could be explained by the resonance between Karman vortex street from the trailing edge of 0.55R-0.6R and the natural frequency of the blade. Therefore the modification of shape around the trailing edge by grinding could almost prevent the singing.
However, recently there were many cases that the propeller singing could not be prevented by the usual measure. In this study, the characeristics of the recent singing and its preventive measures are considered using FFT analyzer of noise occurred on some large ships. In consequence, one of the new antisinging method leading to good results on some applied ships is shown.

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