Spontaneous ignition of single fuel spray was investigated at hot and high pressure air. Ignition lags were studied in relation to air temperature, air pressure, cetane number of fuel and injection pressure. The experimental results are summarized as follows:
(i) Ignition lag can be divided into physical lag and chemical lag by a statistical treatment of a great deal of ignition lag times at same condition.
(ii) Ignition lag decreases according to increasing of air pressure, and the almost part of all ignition lag is physical lag.
(iii) According to increasing of air temperature and cetane number, Ignition lag decreases respectively. In these cases, physical lag and chemical lag decrease together.
(iv) The effect of fuel injection pressure to ignition lag is little.
(v) Ignition lag expressed as follows:
τ= 0.12 p^-0.49 exp. 3750/T
These experimental results suggest that, in hot and high pressure air, physical lag accounts for almost part of all ignition lag. Therefore, control and improvement of combustion in diesel engines must be done in physical process of the spray.

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On a study of prediction or estimation in the reliability, it has been very important to obtain the Failure Rate or the MTBF from a statistical data of reliability test. But, on the other hand, it has not been so easy to get these informations from a field data.
In this paper, we propose that a field data are represented by an autoregressive model (AR model), which is well known as the very useful model in the Time Series Analysis. And this model enables us to predict directly the factors of the reliability. First, we describe the outline of the AR model which is determined by the minimum FPE (Final Prediction Error) procedure proposed by AKAIKE.
Next, an actual data on the mechanical parts installed on Diesel Ship is regarded as the stationary stochastic data and fitted by an AR model, and then the prediction, i.e., the so called one-step ahead prediction is easily obtained using this model.
These numerical examples show that this newly introduced method give us the useful suggestions of the reliability prediction.

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The automation in ships has recently made remarkable progress and the capacity of the electric power in ships has increased; the marine systems have been complicated, so the safety in various machines has been demanded. Particularly the shaft of turbine-generator for the electric propulsion is in danger of being damaged owing to the resonance frequency between the electric and mechanical systems.
This paper describes the analysis of shaft torsional oscillation by means of the computer and the results of experiments in the electric power system to improve the safety in shafts. This is summarized as follows:
(a) The turbine compartments in this program can be changed among two and five in number.
(b) Each unit has the natural frequencies, which range over the rated.
(c) The shaft is in danger of being damaged by the torsional oscillation, after getting rid of the faults.
(d) These wave forms of the oscillation are compared each other in the three-phase and the two-phase short circuit faults by experiments.

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Yanmar Diesel Engine Co., Ltd. developed a totally new concept in propulsion equipment, the YT 1100 system in collaboration with the J.S.M.D.A. (Japan Ship's Machinery Development Association) .
This propulsion system is designed to, with the engine installed on the deck of the stern side of a ship, widen the cargo hold and tank space, reduce the running cost of ship, improve the maintenance, and cut down the facility cost by sharing the power source with auxiliary machinery.
All land tests and subsequent sea trials, in a 499 g/t coastal oil tanker have proved satisfactory as follows.
The ship's running cost can be reduced by effectively utilizing the space available (For example, tank space increased about over 20 percent)
Since the propeller shaft system is included inboard with a sufficient space preserved, servicing and maintenance works are easy and the safety factor is greatly improved.

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This paper deals with the supply technical data on noise and its control on the small and the medium size vessels.
The topics chosen are the ventilating fan noise on the deck, the structureborne noise due to propeller flactuating hydrodynamic forces, the cooling fan noise of the electric eddycurrent coupling for the generator set driven by the main engine, the reactive type exhaust mufflers used for medium or low speed diesel engines, and the abnormal sound of the supercharger of the main engine.

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Frequently heat exchangers in engine rooms are used in various conditions which are considerably different from their designed conditions. This tendency has increased recently, as ships running with reduced speeds increase in number. Therefore it is necessary to estimate their behaviours under such conditions easily and instantly. In these cases, without deep understanding of their natures, the estimation by rule of thumb may often lead to wrong results.
In the paper the estimation method, simple but relatively correct, are shown by the utilization of the empirical fact that the coefficient of overall heat transmission is proportional to (the fluid speed in tube) ⁿ or similar. In addition to the fundamental equations, shown are the individual ones for fuel oil heaters, feed water heaters, lubricating oil coolers and Butterworth sea water heaters as well as calculation examples for them.

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Water addition to combustion system has recently been taken interest as the method of reducing NO_x emission and making better combustion of the fuel oil.
Our company has tried out on decreasing NO_x emission of medium and large size diesel engines and also obtained interesting test results with emulsified fuel oil in cooperation with Mitsubishi Oil Co., Ltd., Dai-ichi Kogyo Seiyaku Co., Ltd. and Mitsubishi Motor Corporation for two years since 1974. It was confirmed on the test benches that the engine became NO_x emission lower and fuel consumption better with emulsified fuel oil.
In this paper, we describe some of its results.

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