Oriented review to potential simulator for faults modeling in diesel engine

This paper presents a literature review on most of the faults and their models that are considered on a diesel engine. Several faults that may be produced on diesel engine have been analyzed, classified, modeled, and their influences on the global system have been shown. Thus, this paper aims to prepare an important data base on diesel engine faults which may help researchers to develop precise strategies on diesel engine fault diagnosis and prognosis, and also it helps in the development of diesel engine simulators aiming to study the behavior of the diesel engine in the presence of faults. Different fault models such as analytical, empirical, degradation models which may be represented as function of time or as function of the number of cycles, data driven models such as neural network models, or simply constant are presented and analyzed. The global overall models for diesel engine integrating faults are expressed. And finally, the use of these models with the most common failure density distribution functions is proposed giving a more realistic approach to our study.     

New procedure for the analysis of speed trial results,with special attention to the correction of tidal current effect

Almost all the existing analysis methods of speed trial results were proposed before 1970s, and the actual analysis procedures are very old-fashioned with instructions like “plot the results on a chart and draw a smooth mean line”, “read a value from the mean line” and so on. Such instructions not only show up the analysis procedures old-fashioned, but also make them very ambiguous and unclear. They should be up-dated to a method which is clear not only in logic but also in calculation procedure, and also fits the present computing technology. At first, the author reviewed the major analysis methods and concluded that the logic of the up-dated analysis procedure can be composed of the logics of the existing ones. Then, the analysis procedure is composed of three stages; namely (1) correction of power and propeller revolution to the ones corresponding to no air condition, (2) correction of tidal current effect, and (3) correction of power and propeller revolution to the ones corresponding to no wind condition. For the stages (1) and (3), there seems to be no big issue except the estimation of the amount of environmentally added resistance in the stage (1). Then, the author focused on the correction of tidal current effect in this paper. For the correction of tidal current effect, the author considers the essential points for the up-date are in the direction of finding out appropriate functions for the variation of tidal current velocity and the ship speed through the water. Then, he investigated to find out such functions and made his proposal. Finally, the applicability of the new procedure is assessed by the analysis of simulated speed trial results of a VLCC.     

Two degree of freedom flow-induced vibration of cylindrical structures in marine environments: frequency ratio effects

The flow-induced vibration of a cylindrical structure is a very common problem in marine environments such as undersea pipelines, offshore risers, and cables. In this study, the vortex-induced vibration (VIV) of an elastically mounted cylinder at a low Reynolds number is simulated by a transient coupled fluid–structure interaction numerical model. Considering VIV with low damping ratio, the response, hydrodynamic forces, and vortex shedding modes of the cylinder is systematically analyzed and summed up the universal rule under different frequency ratios. On the basis of the analysis, we find that the frequency ratio α is a very important parameter. It decides the locked-in, beat, and phase-switch phenomena of the cylinder, meanwhile, it also influence the vortex mode of the cylinder. The trajectory of the two degrees of freedom (2 DOF) case at different natural frequency ratios is discussed, with most trajectories having a “figure of 8” shape and a few having a “crescent” shape. A fast Fourier transformation technique is used to obtain the frequency characteristics of the vibration of the cylindrical structure. Using the 2 DOF cylinder model in place of the 1 DOF model presents several advantages in simulating the nonlinear characteristics of cylindrical structures, including the capacity to model the crosswise vibration generated by in-line vibration.     

Modeling and simulation of a counter-rotating turbine system for underwater vehicles

The structure of a counter-rotating turbine of an underwater vehicle is designed by adding the counter-rotating second-stage turbine disk after the conventional single-stage turbine. The available kinetic energy and the absorption power of the auxiliary system are calculated at different working conditions, and the results show that the power of the main engine and auxiliary system at the counter-rotating turbine system matches well with each other. The experimental simulation of the lubricating oil loop, fuel loop, and seawater loop are completed right before the technology scheme of the counter-rotating turbine system is proposed. The simulation results indicate that the hydraulic transmission system can satisfy the requirements for an underwater vehicle running at a steady sailing or variable working conditions.     

Some insights in novel risk modeling of liquefied natural gas carrier maintenance operations

This study discusses the analysis of various modeling approaches and maintenance techniques applicable to the Liquefied Natural Gas (LNG) carrier operations in the maritime environment. Various novel modeling techniques are discussed; including genetic algorithms, fuzzy logic and evidential reasoning. We also identify the usefulness of these algorithms in the LNG carrier industry in the areas of risk assessment and maintenance modeling.     

Enabling a viable technique for the optimization of LNG carrier cargo operations

In this study, we optimize the loading and discharging operations of the Liquefied Natural Gas (LNG) carrier. First, we identify the required precautions for LNG carrier cargo operations. Next, we prioritize these precautions using the analytic hierarchy process (AHP) and experts’ judgments, in order to optimize the operational loading and discharging exercises of the LNG carrier, prevent system failure and human error, and reduce the risk of marine accidents. Thus, the objective of our study is to increase the level of safety during cargo operations.     

The jurisdictional challenges to the prosecution of piracy cases in Kenya: mixed fortunes for a perfect model in the global war against piracy

Since 2008 Kenya has distinguished itself in the global war against piracy by undertaking prosecutions in the national courts of suspected pirates arrested in the high seas and handed over by navies of leading maritime nations under bilateral agreements (MOUs) entered into between Kenya and these leading maritime nations. As of July 2011, Kenya had over 20 convicted pirates serving jail terms ranging between 7 and 20 years and over 100 suspected pirates awaiting trial in national courts. This is the largest number of suspected pirates held and tried in any one state at any given time in modern history. To achieve this, Kenya had to effect far reaching changes in the law. In the initial stages, suspected pirates were charged under Kenya’s Penal Code (Cap 63 Laws of Kenya). However, the high court in the case of Re Mohamud Mohamed Dashi and eight others [2010] eKLR, ruled that Kenya had no jurisdiction to try suspected pirates under that law. In September 2009, Kenya passed a new law (the Merchant Shipping Act), which not only defined more comprehensively and extensively the offence of piracy, but also extended the jurisdiction of Kenyan courts to try piracy committed by non-nationals. Though the law gives Kenya a very broad jurisdiction to try suspected pirates, the process is still fraught with challenges due to lack of financial and human resources. In the case of Republic vs Hassan Jama Haleys Alias Hassan Jamal and five others [2010] eKLR, the court commented thus:

“… I must note that the ‘piracy trials’ have presented a unique challenge to the Kenyan legal system. We cannot ignore the fact that these are suspects who having been arrested by foreign naval forces on the High Seas are brought to Kenya for trial. They are strangers in the country, do not understand the legal system, may not know what their rights are and do not understand the language… the Kenyan Government and the International partners supporting these trials put in place a system to provide free legal representation for the suspects…”     

Personalization method of e-catalog based on user interesting degree

The user interesting degree evaluation index is designed to fulfill the users’ real needs, which includes the user’ attention degree of commodity, hot commodity and preferential commodity. User interesting degree model (UIDM) is constructed to justify the value of user interesting degree; the personalization approach is presented; operations of add and delete nodes (branches) are covered in this paper. The improved e-catalog is more satisfied to users’ needs and wants than the former e-catalog which stands for enterprises, and the improved one can complete the recommendation of related products of enterprises.     

Simulation of mixed gas formation for a spray-wall complex guided LPG direct injection engine

To obtain an ultralean air-fuel ratio and to reduce engine-out NOX and HC emissions induced by the richer mixture near the spark plug, a spray and wall complex guided combustion system has been developed by utilizing the fuel characteristics of LPG. The new combustion system configuration is optimized by using a commercial CFD code, FIRE V2013, and the reliability of the system has been experimentally demonstrated by Plane Laser-Induced Fluorescence (PLIF). The mixture formation in the new combustion system under part load (2,000 rpm) is numerically simulated. With an injection timing of 40°CA BTDC, the LPG spray which is injected from two upper holes, reaches the ignition point, and the other part of the LPG spray which is injected from the bottom hole, is directed to the ignition point through the vertical vortices at the same time. At the ignition timing of about 20°CA BTDC, the two-part mixtures have been shown to form a stable and richer stratified mixture around the ignition point, and the maximum global air-fuel ratio reaches to 60: 1.