A new approach is outlined for analysing the field reliability of the mechanical items which are under preventive maintenance.
A failure-mechanism model is obtained directly from the field data, by a strict interpretation discriminating the informations concerned about the failures and prefailure defects or abnormalities, recorded in the conventional reports. It can be approximated by a known distribution and conveniently used for data analysis. The validity of this macroscopic model is shown in the applications to several cases of actual data of the marine products.
The approach does not require any prior knowledge of the distribution, and Pandit called it “Data Dependent Systems Approach” in his Tool-life investigations.

View full abstract

The conventional characteristic method has been used almost exclusively in analysing the unsteady flow in internal combustion engines for a long time.
In this paper, the Two-step Lax-Wendroff's method, one of the methods called difference calculus, is proved to be very useful in the analysis of unsteady flow in internal combustion engines, because of some features of the method.
The conventional method has the disadvantages that the simulated flow quantity at a crosssection of the flow stream is not always equal to that at other sections and that the required calculation time is rather too long.
By using the Two-step Lax-Wendroff's method, the mentioned problems have been solved.
Other items discussed in this report are (1) a comparison of pulses near the ports during blow-down in an experimental unit for a single blow-down with that in a unit for periodically continuous blow-downs, (2) the wave characteristics at a pipe-end nozzle and at an orifice in the pipe, and (3) the difficulty of obtaining similar pulsations in all the connecting ducts which connect cylinders with the main exhaust pipe in actual engines.

View full abstract

This paper presents some findings obtained by the running tests of the hydrogen-gas oil dual fuel diesel engine.
The experimental work was carried out on the small size, single cylinder, four stroke cycle, pre-combustion chamber diesel engine with the compression ratio of 20: 1.
In this dual fuel engine, the hydrogen was injected into the intake pipe, mixed with the fresh air, compressed and then ignited by the injection of gas oil near the end of compression stroke. The hydrogen-gas oil dual fuel diesel engine ran smoothly as the hydrogen-air equivalence ratio was smaller than the values of 0.2-0.3 depending on the running conditions of the engine.
But, the preignition began to occur when the hydrogen-air equivalence ratio became larger than the values of 0.2-0.3.
The preignition led rough running and poor thermal efficiency of the dual fuel diesel engine.
With the object of controling the preignition, we tried to inject water near the intake valve in the intake pipe and to lower the temperature of the fresh air by the evaporation heat of water. By the water injection into the intake pipe, the hydrogen-gas oil dual fuel diesel engine could run widely in the hydrogen-air equivalence ratio without the abnormal combustion.

View full abstract

The researches on identification of additives of lubricating oil in bilge were carried out with the infrared spectroscopy.
We added methanol of equivalent volume to samples under heating by water bath and mixing by magnitic stirrer, and desolved the additives of lubricating oil to methanol.
The solvent was then removed and residual substance was examined by the infrared spectroscopy.
On this report in the manner described above, we made the experiment to identify additives of lubricating oil in the ship's bottom bilge.
This method may be applied to identify the bilge contained lubricating oil in discharge accidents of oily water into the sea.

View full abstract

To find out an optimum cycle of the ship bottom sweeping from the standpoint of service economics, an accurate increase in delivered horsepower due to the ship's bottom fouling was grasped and a statistical analysis was made referring to the deck logbook and the engineer's logbook in parallel with speed tests with actual vessels.
Some findings are as follows: (1) Values measured in speed tests before and after docking under conditions of 6200 tonne dwt and a given speed revealed that the annual increase in delivered horsepower due to the ship bottom fouling would be about 1000PS. (2) Variations in a decade, taking the initial service as the original point, both in delivered horsepower and in fuel consumption was at between about 10 and 15% increase.

View full abstract