Comparison of diesel-electric with hybrid-electric propulsion system safety using system-theoretic process analysis

Cruise ship industry is rapidly developing, with both the vessels size and number constantly growing up, which renders ensuring passengers, crew and ship safety a paramount necessity. Collision, grounding and fire are among the most frequent accidents on cruise ships with high consequences. In this study, a hazard analysis of diesel-electric and hybrid-electric propulsion system is undertaken using System-Theoretic Process Analysis (STPA). The results demonstrate significant increase in potential hazardous scenarios due to failures in automation and control systems, leading to fire and a higher number of scenarios leading to propulsion and power loss in hybrid-electric propulsion systems than on a conventional cruise-ship propulsion system. Results also demonstrate that STPA enhancement is required to compare the risk of two propulsion systems

Reminiscences on Influential Papers

Reminiscences on Parallel evaluation of multi-join queries. (Proc. SIGMOD Conf. 1995), Annita Wilschut, Jan Flokstra, Peter M.G. Apers

The Business Value of Gamification

This article analyzes the connection between gamification and business success, focusing on customer retention, new customer acquisition, and transforming user perceptions. Based on a qualitative comparative analysis of 40 high-profile gamification projects, it shows that a combination of three key features—virtualization, social comparison, and tangible rewards—explain the various pathways to success. Each pathway requires the presence—and sometimes absence—of different design features, and firms do best when they focus on one or two objectives rather than all three at once. The article presents a framework for designing and implementing gamification more strategically and effectively, noting the ethical questions that arise

A methodology to define risk matrices–application to inland water ways autonomous ships

The autonomous ships’ introduction is associated with a number of challenges including the lack of appropriate risk acceptance criteria to support the risk assessment process during the initial design phases. This study aims to develop a rational methodology for selecting appropriate risk matrix ratings, which are required to perform the risk assessment of autonomous and conventional ships at an early design stage. This methodology consists of four phases and employs the individual and societal risk acceptance criteria to determine the risk matrix ratings for the groups of people exposed to risks. During the first and second phase, the required input parameters for the risk matrix ratings based on the individual risk and societal risk are calculated, respectively. During the third phase, the risk matrix ratings are defined using input from the first and second phases. During the fourth phase, the equivalence between the different types of consequences is specified. The methodology is applied for the case study of a crewless inland waterways ship to assess her typical operation within north-European mainland. The results demonstrate that the inclusion of societal risk resulted in more stringent risk matrix ratings compared to the ones employed in previous studies. Moreover, the adequacy of the proposed methodology and its effectiveness to provide risk acceptance criteria aligned with societal and individual risk acceptance criteria as well as its applicability to conventional ships are discussed

Using system-theoretic process analysis and event tree analysis for creation of a fault tree of blackout in the diesel-electric propulsion system of a cruise ship

Diesel-Electric Propulsion (DEP) has been widely used for propulsion of LNG carriers, icebreakers, drilling units, warships and cruise ships. It is important that every blackout is prevented, especially on cruise ships, considering the possible consequences of such an event. In this work, hazard analysis of a simplified DEP system of a cruise ship is implemented to identify the hazardous scenarios leading to a blackout. This is achieved by combining System-Theoretic Process Analysis (STPA) and Event Tree Analysis (ETA). The STPA is used to identify the hazards and the possible control actions leading to hazards along with their causal factors, whilst the ETA is used to determine the propagation of hazards into the other hazards or accident. Next, the results of STPA and ETA are mapped into a Fault Tree for better representation of results. In this way, the relationship between accident, hazards and unsafe control actions is explicitly described and a more comprehensive picture of the potential accidental scenarios in the system is provided, rendering possible allocation of quantitative performance requirements as per IEC 61508

DAIMON: Data Integration for a Mobile Network

We describe the DAIMON system for data integration of nomadic data. DAIMON is based on an extension of the mediator-wrapper architecture, where each node is a mediator of its own information and information from its neighbouring nodes. We describe the overall architecture, including our lightweight peer location and neighbourhood identification scheme, cache management strategy and query processing and execution architecture, and show how it addresses the challenges of the wireless environment. We introduce connectivity profiles for mobile peers to capture their different connectivity, availability and accessibility patterns, and we describe how they can be used to guide query processing and optimization decisions by the mediator module of the mobile peers. The implementation of the DAIMON system is also discussed