A seakeeping analysis method for an air-lifted vessel

A seakeeping analysis in the frequency domain is presented to predict the motion response of an airlifted vessel (ALV) in waves. The ALV is supported by pressurised air in two separate cushion chambers; the pressure variation in the cushions has a significant effect on the motions of the vessel. The adiabatic gas law is used to couple cushion pressure and the free-surface elevation of water inside the chamber. Attention is focused on the waves generated by the pressure, and a method is presented to compute the corresponding free-surface elevation. New numerical schemes are proposed for calculating the threedimensional free-surface elevation for the four wave numbers. Numerical results of the free-surface elevation, escape area, escape volume and motion responses of the ALV are provided. & 2008 Elsevier Ltd. All rights reserved

Consumer Purchase Likelihood of Landscape Management Pest Scouting Program

The US landscape industry consists of 632,000 businesses with >1 million persons employed in 2022. The most common service that landscape service providers (LSPs) perform is pest management. Over the past 25 years, LSPs have been challenged to adopt more holistic approaches to pest management via the use of nonchemical and less toxic chemical controls. Integrated pest management (IPM), specifically scouting, may be a useful approach for LSPs to manage pests more sustainably and market new services, such as biological control releases. Scant literature is available on LSP scouting practices or consumer acceptance of scouting services. The goal of this study was to determine if IPM-aware consumers were more likely to purchase a scouting program offered by an LSP. An online survey was distributed across the United States through a third-party panel service. The final sample included 928 usable responses. Data were analyzed using a binary logistic regression model. Fifty-seven percent of respondents reported having some knowledge or were very knowledgeable of IPM. Respondents 65 years of age and older were 13.1% points less likely to purchase a scouting service. Education level did not influence purchase likelihood. Consumer knowledge of IPM had a positive influence on the purchase likelihood, respondents with “some knowledge” (5.6%) and “very knowledgeable” (8.6%) were more likely to buy IPM services. Further, if the consumer was open to purchasing the scouting program, it is plausible that they might be more willing to allow an LSP to use a combination of chemical and nonchemical methods to manage pests

Evolution and Phylogenetic Analysis of Full-Length VP3 Genes of Eastern Mediterranean Bluetongue Virus Isolates

Bluetongue virus (BTV) is the ‘type’ species of the genus Orbivirus within the family Reoviridae. The BTV genome is composed of ten linear segments of double-stranded RNA (dsRNA), each of which codes for one of ten distinct viral proteins. Previous phylogenetic comparisons have evaluated variations in genome segment 3 (Seg-3) nucleotide sequence as way to identify the geographical origin (different topotypes) of BTV isolates. The full-length nucleotide sequence of genome Seg-3 was determined for thirty BTV isolates recovered in the eastern Mediterranean region, the Balkans and other geographic areas (Spain, India, Malaysia and Africa). These data were compared, based on molecular variability, positive-selection-analysis and maximum-likelihood phylogenetic reconstructions (using appropriate substitution models) to 24 previously published sequences, revealing their evolutionary relationships. These analyses indicate that negative selection is a major force in the evolution of BTV, restricting nucleotide variability, reducing the evolutionary rate of Seg-3 and potentially of other regions of the BTV genome. Phylogenetic analysis of the BTV-4 strains isolated over a relatively long time interval (1979–2000), in a single geographic area (Greece), showed a low level of nucleotide diversity, indicating that the virus can circulate almost unchanged for many years. These analyses also show that the recent incursions into south-eastern Europe were caused by BTV strains belonging to two different major-lineages: representing an ‘eastern’ (BTV-9, -16 and -1) and a ‘western’ (BTV-4) group/topotype. Epidemiological and phylogenetic analyses indicate that these viruses originated from a geographic area to the east and southeast of Greece (including Cyprus and the Middle East), which appears to represent an important ecological niche for the virus that is likely to represent a continuing source of future BTV incursions into Europe

Formal Safety Assessment of a Marine Seismic Survey Vessel Operation, Incorporating Risk Matrix and Fault Tree Analysis

In maritime safety research, risk is assessed usually within the framework of formal safety assessment (FSA), which provides a formal and systematic methodology to improve the safety of lives, assets, and the environment. A bespoke application of FSA to mitigate accidents in marine seismic surveying is put forward in this paper, with the aim of improving the safety of seismic vessel operations, within the context of developing an economically viable strategy. The work herein takes a close look at the hazards in North Sea offshore seismic surveying, in order to identify critical risk factors, leading to marine seismic survey accidents. The risk factors leading to undesirable events are analysed both qualitatively and quantitatively. A risk matrix is introduced to screen the identified undesirable events. Further to the screening, Fault Tree Analysis (FTA) is presented to investigate and analyse the most critical risks of seismic survey operation, taking into account the lack of historical data. The obtained results show that man overboard (MOB) event is a major risk factor in marine seismic survey operation; lack of training on safe work practice, slippery deck as a result of rain, snow or water splash, sea state affecting human judgement, and poor communication are identified as the critical risk contributors to the MOB event. Consequently, the risk control options are focused on the critical risk contributors for decision-making. Lastly, suggestions for the introduction and development of the FSA methodology are highlighted for safer marine and offshore operations in general

Risk-based ship design

Risk-based ship design is a new scientific and engineering field of growing interest to researchers, engineers and professionals from various disciplines related to ship design, construction, operation and regulation. This chapter aims to present an overview of risk-based design developments over the recent past and to attempt to demonstrate that substantial pre-requisite scientific and technological developments are in place for Risk-Based Design to be fully implemented in the maritime industry. To elucidate the realisation of the risk-based ship design concept through application, a variety of examples at basic and holistic levels using RoPax and cruise liners are presented and discussed in the second part of the present chapter

Time-based survival criteria for passenger ro/ro vessels

This paper outlines the study undertaken within the framework of research aiming to address the compound problem of the absolute time available for passenger evacuation on a damaged passenger/RO/RO vessel undergoing large-scale flooding of car deck spaces. Deriving from extensive experimental information and utilizing static equivalent method (SEM) principles, a methodology for predicting ship survival time is proposed that accounts for wave characteristics, water ingress/egress, and vessel survivability. The progress achieved to date is discussed, and aspects needing further investigation are highlighted

New insights into ship-floodwater sea dynamics

This paper aims to clarify a number of issues concerning the dynamics of a damaged ship, interpreting the results of recent towing tank tests by means of a simplified linear model with two degrees of freedom. In this sense, this work can be seen as the natural evolution of the extensive body of work in this field undertaken by the SSRC during a long series of large research projects, including the Joint North West European Project [2], the MCA funded Time Based Survival Criteria of Passenger Ro-Ro Vessels, Phase 1 and 2 [3] and, above all, the Fifth EC Framework RTD projects HARDER and NEREUS [1], during which the experimental evidence presented in this paper was collected