This paper analyzes the shipowner's role in the development process of ship's computerized planned maintenance system database, paying specific attention to his/her impact on database quality grades resemblance equalization. The paper describes the database development process from the realization that the database is needed to the installation on board vessel, and all shipowner's and developer's actions in the process.The computerized databases of five shipping companies were tested using questionnaire developed for this purpose. of office user's workload with regard to the administration and correction of data besides database quality grades: that data serves to portrait the relation between data quality in the databases and importance given to the process of development and maintenance of the databases. The analysis of the results yields numerical values as indicators of shipowner's input on the resemblance of grades of both scenarios and on the database quality grades resemblance equalization.The conclusion shows how the shipowner affects the ship's computerized planned maintenance system database and what actions should be performed to obtain the final product (database, i.e. data in the database) as good as possible and, thus, maintenance of the ship and the whole system.The expected results of the paper are: -To analyze in detail the database ordering and development process, -To pinpoint controlling areas for the database quality, -To analyze the shipowner's impact on the database quality grades resemblance equalization.

No abstract

The paper presents the initial case of a research of analysing maintenance interval adjustment in the shipping industry. This case is an example of the adjustment of the maintenance interval carried out by ship's crew on starting air compressor system. The example is found and followed through the records in the computerized Planned Maintenance System. Maintenance interval adjustment proposal and actual adjustment were carried out based on user's experience, after rechecking maintenance data and actual machinery condition, without theoretical approach or analysis. That process created new maintenance plan which is in use on the system for past ten years. Missing actions in the process, i.e. theoretical analysis of the initial and modifi ed maintenance, are performed using the MA-CAD method with a modifi ed reliability testing and are described in the paper. Results obtained by the theoretical analysis are compared with the requested and performed modifi cation of the Maintenance Plan and a conclusion about performed action has been derived. Sažetak U radu je predstavljen inicijalni slučaj istraživanja analize podešavanja intervala održavanja u brodskoj industriji. Ovaj slučaj je primjer podešavanja intervala održavanja koji obavlja brodska posada pri pokretanju sustava kompresora. Primjer smo pronašli i pratili kroz evidenciju u računalnom sustavu planiranog održavanja. Prijedlog podešavanja intervala održavanja i stvarno podešavanje provedeni su na temelju iskustva korisnika nakon ponovne provjere podataka o održavanju i stvarnog stanja stroja bez teorijskog pristupa ili analize. Taj je postupak rezultirao novim planom održavanja koji se u sustavu koristi posljednjih deset godina. Radnje koje nedostaju u tom postupku, tj. teorijska analiza inicijalnog i modifi ciranog održavanja, provedene su primjenom MA-CAD metode s modifi ciranim ispitivanjem pouzdanosti i opisane su u ovom radu. Rezultati dobiveni teorijskom analizom uspoređuju se s traženom i izvedenom modifi kacijom Plana održavanja i donesen je zaključak o izvršenim radnjama.

As part of the research on high speed radial diesel engines, an analysis had been conducted on the use of the operating systems of the missile boats and comparison of the results with the manufacturer’s recommendations. A graphic model had been set up (block – diagram) on high speed radial ship diesel engine. On the basis of research and empirical data collected on defects which cause the inability to use the engine, the total exploitation reliability of complex technical system and the statistical characteristics of the life of the system had been defined, starting from the assumption that the life of the technical system tested belongs to the Weibull distribution. Research results had been achieved by means of the simulation method (the simulation model) and then were tested with the use of the contemporary computer applications. By defining the levels of operational capability, the levels of reliability had eventually been set up and they need to be ensured through modified maintenance procedures so that the investigated technical system could meet the required criteria. In the research of new samples, the needed intervals of preventive replacement of critical system parts will be determined so that the demanded reliability would be ensured.

A numerical study is conducted to compare the current most popular flow field configurations, porous, biporous, porous with baffles, Toyota 3D fine-mesh, and traditional rectangular flow field. Operation at high current densities is considered to elucidate the effect of the flow field designs on the overall heat transfer and liquid water removal. A comprehensive 3D, multiphase, nonisothermal computational fluid dynamics model is developed based on up-to-date heat and mass transfer sub-models, incorporating the complete formulation of the Forchheimer inertial effect and the permeability ratio of the biporous layers. The porous and baffled flow field improves the cell performance by minimizing mass transport losses, enhancing the water removal from the diffusion layers. The baffled flow field is chosen for optimization owing to the simple design and low manufacturing cost. A total of 49 configurations were mutually compared in the design of experiments to show the quantitative effect of each parameter on the performance of the baffled flow field. The results elucidate the significant influence of small geometry modifications on the overall heat and mass transfer. The results of different cases have shown that water saturation can be decreased by up to 33.59% and maximal temperature by 7.91 °C when compared to the reference case which is already characterized by very high performance. The most influencing geometry parameters of the baffles on the cell performance are revealed. The best case of the 49 studied cases is further optimized by introducing a linear scaling factor. Additional geometry modifications demonstrate that the gain in performance can be increased, but at a cost of higher pressure drop and increased design complexity. The conclusions of this work aids in the development of compact and high-performance proton exchange membrane fuel cell stacks.