Investigation of the optimum longitudinal single transverse step location for a high-speed craft

One of the crucial aspects of the conceptual design of a stepped planing hull is the prediction of its performance. To improve performance, the prediction of total resistance must become more accurate. In the field of research, both towing tank experiments and numerical analysis may be used to achieve this goal. In this study, experiments were conducted initially to investigate total resistance of a relatively high-speed craft without a transverse step. Later, numerical computations were carried out to validate the experimental results. After it was determined that the test results and CFD methods were in good agreement, the experimental method continued to investigate the resistance properties of the hull with four different configurations to evaluate the optimal longitudinal position of a single transverse step. The ideal longitudinal position of the single transverse step was evaluated based on a similar relatively high-speed hull with a velocity of up to beam Froude number (FrB) 2.56 in this study, focusing on the FrB range between 2.30 and 2.45

A novel approach for planning of shipbuilding processes

Shipbuilding is acknowledged as an uncertain, complex, and unique industrial effort that yields massive products consisting of numerous parts and is vulnerable to unexpected events. The industry is also dominated by customer requirements through designs tailor-made for a specific ship. Planning in shipbuilding is therefore considered a formidable process. Consequently, many studies have been conducted to develop a planning framework for the industry to efficiently handle planning process. Yet none of these studies are deemed substantial enough to be regarded as holistic, straightforward, well-accepted, and compatible with the nature of shipbuilding. This study is therefore an important contribution by presenting a novel, hybrid, and integrated general-purpose planning framework applicable to all shipbuilding processes. The novel method exploits historical ship construction scheduling data, synthesizing hierarchical planning, dynamic scheduling, and discrete-event simulation, which is validated through an empirical study in this paper

WAVE FIELD GENERATED BY FINITE-SPAN HYDROFOILS OPERATING BENEATH A FREE SURFACE

The present paper focuses on the numerical investigation of the flow around the fully submerged 2D and 3D hydrofoils operating close to a free surface. Iterative boundary element method is implemented to predict the flow field. This study aims to investigate the aspect ratio effect on the free surface interactions and hydrodynamic performance of the hydrofoils under a free surface by using potential flow theory. Three different submergence depths and aspect ratios are studied in the wide range of Froude Numbers. In 3D cases, spanwise width of the numerical wave tank model is selected both equal and wider to the foil span, to observe the sidewall effects. Wave field seems to be two dimensional at low Froude numbers. On the other hand, signs of three dimensionalities are observed on the free surface structure for higher Fn, even the predicted wave elevations are very close to 2D calculations in the midsection. Increment in the Fn give a rise to the amplitude of the generated waves first, however a further increase in Fn has a lowering effect with the beginning of waves spill in the spanwise direction in the form of Kelvin waves. Free surface proximity and resultant wave field are also seeming to be linked with the lift force on the hydrofoil. As aspect ratio of the foil increase, 3D lift values are getting closer to those of 2D calculations. However, it is seen that, 3D BEM predictions of a hydrofoil under free surface effect cannot be considered two-dimensional even the aspect ratio is equal to 8

A STUDY ON THE IDENTIFICATION OF FIRE HAZARDS ON BOARD: A CASE STUDY

The RoRo ship MS UND ADRIYATIK was wrecked in February 2008 by a catastrophic fire. The causes of the accident included a combination of human, technical and organizational factors. In this study, the authors describe the accident, its chronology, and the dependencies involved. They then examine some of the erroneous series of human’s operations, design and technical errors that led to the disaster and their organizational roots at the time of the accident. Risk-reduction measures can be costly, though; priorities must be set based on costs and benefits. This research suggests ways to support fire prevention efforts. Nine possible reasons were determined to perform a survey suitable for AHP technique. The purpose of this survey is to determine the order of possible explanations for this fire accident and possible provisions and precautions to be taken

FREE SURFACE FLOW SIMULATION AROUND AN APPENDED SHIP HULL

This study brings forward the results of previously published work of free surface flow simulation around a fast ship model. Experimental measurements and numerical simulations of a fast bare-hull ship model form are now extended to the same ship form with appendices for a wide range of Froude numbers. The governing equations are discretized by means of an unstructured finite volume mesh. The standard k-ε turbulence model and Volume of Fluid Method to capture the two phase media are used. The total resistance, due to wave and wake fields of the ship model with appendages and the resistance of the appendages alone are calculated numerically, and compared with the experiments. The experiments and computations were performed for 11 different Froude numbers between 0.103 and 0.322. For Froude numbers up to 0.25, numerical simulations found to be quite in agreement with the experiments. It has been found that appendages increase the total drag mainly by increasing the pressure resistance, and the effect of the appendages becomes more important as the flow speed gets higher

Transferrin-Decorated Niosomes with Integrated InP/ZnS Quantum Dots and Magnetic Iron Oxide Nanoparticles: Dual Targeting and Imaging of Glioma

The development of multifunctional nanoscale systems that can mediate efficient tumor targeting, together with high cellular internalization, is crucial for the diagnosis of glioma. The combination of imaging agents into one platform provides dual imaging and allows further surface modification with targeting ligands for specific glioma detection. Herein, transferrin (Tf)-decorated niosomes with integrated magnetic iron oxide nanoparticles (MIONs) and quantum dots (QDs) were formulated (PEGNIO/QDs/MIONs/Tf) for efficient imaging of glioma, supported by magnetic and active targeting. Transmission electron microscopy confirmed the complete co-encapsulation of MIONs and QDs in the niosomes. Flow cytometry analysis demonstrated enhanced cellular uptake of the niosomal formulation by glioma cells. In vitro imaging studies showed that PEGNIO/QDs/MIONs/Tf produces an obvious negative-contrast enhancement effect on glioma cells by magnetic resonance imaging (MRI) and also improved fluorescence intensity under fluorescence microscopy. This novel platform represents the first niosome-based system which combines magnetic nanoparticles and QDs, and has application potential in dual-targeted imaging of glioma

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Numerical computation of the interaction of surface waves with submarine pit breakwaters

849-858Present study consists the interaction of surface waves with submarine pit breakwaters. A vertically-integrated nonlinear dispersive wave model with inclusion of a semi-empirical wave breaking effect, in non-orthogonal curvilinear coordinate system is used for simulating waves. The staggered grid system is used. Matrix equation of the finite difference method is solved through an iterative approach at each time step. Numerical method results in implicit formulations for the momentum equations and explicit formulation for the continuity equation. The numerical model has been validated through comparisons of computational results with experimental measurements of the wave propagation over an asymmetrical trapezoidal bar, over shoals and the regular wave diffraction results for rectangular pit. Simulations show an acceptable level of agreement and give confidence for practical applications. </span