From time to time the authors have been receiving enquiries from engine builders and operators about the reason why diesel engine oils or gas engine oils have both basicity and acidity. In order to respond to the enquiry, the principle of acidity and basicity measurements in color-indicator titration of aqueous solutions is explained. Similar methods are used to determine neutralization values of non-aqueous solutions such as petroleum products, even though electrometric titration is more suitable for darker-colored oils and used oils. The practical importance of neutralization value tests is also discussed, with particular reference to diesel and gas engine oils.
Though a gantry crane (GC) is indispensable for loading and unloading cargo on to a ship, there have almost never been reported about its characteristics of reliability and maintainability from the practical and statistical viewpoint. Therefore, the object of this paper is to make clear the relationships among the method, policy and reasons of replacement of wire rope which is the most important part in GC. We pick up the data of the wire rope from many parts which compose GC and then analyze its maintenance data through the Weibull probability paper and Weibull type of the cumulative hazard paper. First we discuss the outline of maintenance method of the wire rope based on the theoretical equations and next propose newly the statistical analysis of the data gathered from the maintenance field. Finally, we show that the results obtained here have very useful information about the relationship between the maintenance method and the cumulative number of cargo dealt with GC.
This paper evaluates the subgrid scale (SGS) models of Large-Eddy Simulation (LES) in the Fire Dynamics Simulator (FDS), which is the Computational Fluid Dynamics (CFD) code developed at the National Institute of Standards and Technology (KIST) for practical use. LES results of three SGS models (Smagorinsky model, Structure-Function model and WALE model) are compared to fire experimental data of fully developed flow fields in a compartment with an opening. On the other hand, the influence of the three SGS models on transient flow fields at an initial stage of compartment fire phenomena was investigated in terms of time evolution of the temperature by a heat detector model. Further, it is employed to study the effect of the SGS models on unsteady flow fields with simple harmonic oscillation, which is used as a very simplified model of ship rolling motion. From the numerical simulations, it is found that there is no critical difference between the results by the above SGS models. This leads to the conclusion that the Smagorinsky model, which is adopted in FDS by default, works well in practical fire dynamics simulations though it is a primitive SGS model in comparison with the other two improved models.