This paper describes the method to detect the abnormal engine condition by means of an algorithm of the neural network, which is modeled upon information processing capability of the operater. The 4-cycle diesel engine is used in this experimental study. As for kinds of engine abnormalities, the leak of the gas from the exhaust pipe and the abnormal combustion depending on F.O. cut are taken as an example. The neural network is composed of the units and the weights which link between units. When the engine is operated by the normal condition, the spectrum data of the radiation sounds from the engine are put in the input layer in the neural network. By learning those data, the weights are formed between units. We judge whether the engine is the normal condigion by using this neural network. Under the normal condition, the correct recognition rate is almost 80% or over both the exhaust leak experiment and the fuel cut experiment. On the other, in case of the abnormal condition, the correct recognition rate is 20% or less in two kinds of experiments. For the results mentioned above, this method using the neural network could satisfactory detect two kinds of abnormal condition.
The amount of transportation of water-soluble toxic chemicals by ships is very large. It is concerned that an outflow accident of such chemicals might cause the undesirable influence on the ocean environment before the dilution process with sea water will make them harmless. The diffusion process beneath the sea surface of water-soluble chemicals spilt from ships at a collision or stranding is similar to that of hot drain from land based power plants. In case of hot drain, a lot of research have been done and its diffusion process, Which is usually treated as the gravitational plume considring the density difference between hot drain and surrounding sea water, has almost been elucidated. In case of watrer-soluble chemicals, however, the density difference distributes widely depending on the substances and usually differs from that of hot drain. Moreover some chemicals release reaction heats when it defuses in sea water. It has not been confirmed yet that the evaluatoin method based on dimensionless numbers and the empirical correlations proposed in the past reports can be applied to such chemicals. Then to make this problem clear, some experiments using a small-scale tank were conducted. As experimental solutes, three kind of typical chemicals with different properties were selected. Experimental parameters were the outflow rate and the relative velocity between the spilling source and surrounding water. The diffusion characteristics such as the direction and width of the plume were observed and compared with the empirical correlations published so far. As a result, it was found that the diffusion characteristics except one chemical can well be estimated by the method applied to the gravitational plume of hot drain if Froude number is chosen as the controlling dimensionless number, although a different result was anticipated because the transport properties and density of chemicals used in the experiment are very different from those of hot drain.
This paper presented the reduction methods of NOx emission from not marine diesel engines, but marine transportation. In the first part of the paper, evaluations of NOx emission from sailing ships based on naval architecture and marine engineering were examined theoretically. Then, in order to demonstrate the evaluations, fuel injection timing retard and sailing performance under two different conditions (before and after drydock) were examined by using a 603GT/1618kW ship equipped with controllable pitch propeller. The results obtained from the examinations are as follows : (1) the quantity of NOx emission per dead weight and sailing distance that evaluates the emission from sailing ships including engine performance and hull performance is more proper for the NOx estimation than the quantity of the emission per unit time and engine output that evaluates the emission only from engines ; (2) NOx emission from sailing ships can be decreased by reducing NOx emission from engines, coefficient of total resistance and ship speed, and also by increasing propeller efficency ; (3) NOx emitted from ships can be decreased in a global scale by giving attention to the synthetic transport efficiency.
The prediction of flow patterns is the basis for modeling the two-phase flow and heat transfer. The annular flow transition is the most important phenomenon and the several models have been proposed. As the body forces largely control the flow behavior, gravity is a key parameter in the transition models. However, it has been very difficult to prove its influence. The existing transition models were compared with the experimental results at microgravity conditions during parabolic trajectory flights on aircraft. The influence of gravity on the annular flow transition was discussed and the existing models were verified.
This paper describes the results of lube oil consumption test in order to ensure sufficient reliability of a diesel engine, employing a prototype engine of 200 mm-diameter cylinder. The authors have tried to use a high-precision laser displacement detector in detecting the change of the lube oil surface levels in order to obtain the lube oil consumption rate when the continuous operation of the diesel engine is being performed. It was confirmed that the measurement of the lube oil consumption rate of the engine by using a laser displacement detector is more effective than the conventional method of measuring the lube oil level by visual observation. And, this paper presents the achievements that have been obtained through the tests as above described.
We have carried out stability testes of emulsion, and corrosion tests of engine parts, in laboratory and test engine, for reliability of engine, using water-emulsifield fuel. The following has been found. (1) . High water content emulsion of A-marine diesel oil without surfactant has low stability, so that, separation of oil and water occur within a few minutes. However, one with surfactant is very stable, and is able to use practically. (2) . In case of C-marine fuel oil, emulsion without surfactant is stable. (3) . The emulsified fuel without surfactant is extremely corrosive, However, one with surfactant is not corrosive. (4) . Water-emulsified fuels cause significant abration to the plunger and barrel of the fuel injection pump. A TiN-coated plunger is used as a effective method against abration.
Nippon Kaiji Kyokai is now trying to detect the lubricating conditionas on marine machinery by applying ferrography. After studying the relationships between the inspection results by surveyors and the used oil analysis results, we reached the conclusion that, if the direct reading ferrograph (DR) shows to be under a certain limit on each machinery that system is in a good lubricating condition at high reliability. This paper reports the mean DR values of 2 cycle diesel engine, steam turbine and oil lubricated stern tube where good lubricating conditions are observed.