Naval Field Research Articles

Comparative analysis of bio fouling microorganisms after treatment with glidarc

The biofouling of the surfaces immersed in water is one of the most important problems which must be solved in the naval field. This phenomenon is amplified during the harbor operations, when the ships are stationary and there is a high density of microorganisms in the neritic area, developing the biofouling. For this reason, in order to prevent or delay the deposition of the first layers of biofouling, different methods have been used [1]. This paper presents the comparative analysis of microorganisms’ behavior obtained by using GlidArc technology for the treatment of the naval metallic surfaces [2, 3]. The main parameters identified for data processing were: the number of microorganisms shared from the point of view of sensibility to the used technology found on the metallic surfaces, the type of the naval paint and the treatment methods. For analysis it was used the epifluorescence microscopy method with. The comparative analysis follows the data processing which has the same input characteristics. Finally it was observed the microorganism's lifetime after the surface treatment.

무인수상정 탑재 소나시스템 개발

ABSTRACT Recently, unmanned systems are largely utilized in various fields due to the persistency and the least operational risk and an unmanned surface vehicle(USV) is the one of the representative application in the naval field. To assign multiple roles to an USV, we developed a sonar system which consists of a forward detecting sonar for the long-range detection, a downward detecting sonar for the small target scan and identification, and a strut type body for mounting sonar systems. In this paper, we described the developed sonar system for USV and the sea test results for verifying system performance. The test results showed that the developed sonar system was able to detect the underwater target about several kilometers away and could recognize a small object at the downside of the sonar system. We expect that the developed sonar system will be easily applied to other unmanned platforms without serious consideration.Key Words : Unmanned Surface Vehicle(무인수상정), Sonar System Development(소나시스템 개발), Forward Detecting Sonar(전방탐지소나), Downward Detecting Sonar(하방탐지소나)

Experimental and numerical analysis of fillet-welded joints under low-cycle fatigue loading by means of full-field techniques

The welded structures used in the naval field are generally subjected to fluctuating stress over time. In some structural welded details, due to changing loading conditions, significant elastic-plastic deformation can arise, which may lead to the failure of the structure after a relatively low number of cycles. The aim of this scientific work was to investigate the behavior of welded T-joints under low-cycle fatigue using full-field techniques: digital image correlation and infrared thermography. Low-cycle fatigue tests were carried out on welded “small-scale” specimens with the aim of obtaining loading and boundary conditions similar to those that occur in “large-scale” components in their real operating conditions. A nonlinear finite element analysis was also performed. The material curves, relative to different zones (base material, heat-affected zone, weld), were obtained by hardness measurements, which were done by means of a fully automated hardness scanner with high resolution. This innovative technique, based on the ultrasonic contact impedance method, allowed to identify the different zones (base material, heat-affected zone, weld metal) and to assess their cyclic curves, which were considered in the finite element model. Finally, the finite element model was validated experimentally comparing the results with the measurements obtained using the digital image correlation technique. The applied procedure allows providing useful information to the development of models for the prediction of fracture and fatigue behavior of the welded joints under the low-cycle fatigue loading.

Composite Laminates under Dynamic Extreme Conditions

Glass fibre laminates were subjected to experimental low velocity impact tests at three different temperatures, room, T = -25 °C, T = -50 °C, and the results were compared to investigate the impact behaviour in extreme conditions of composites applied in naval field. The experiments were carried out, first, at complete penetration of the specimens and then, at different energy values to investigate on the damage initiation and propagation. The indentation depths and the delaminated areas were measured and analyzed to validate existing semiempirical models for the prediction of the response of these materials in dynamic shock conditions, at the aim to help the navigation in the Artic Ocean in safety conditions.

Microscopic Approach to Evaluate Energy Consumption and Emissions from Ships

Maritime transport plays a central role in the debate about the sustainability of the transport sector. Analyses suggest that air emissions from shipping account for a significant portion of total emissions, affect air quality, and contribute to climate change and human health problems. The existing trend suggests that the situation will worsen. These results, though affected by obvious uncertainties, highlight the urgent need to take action. Harmful environmental impacts are controlled primarily through legislation prohibiting the use of certain substances, setting limits on emissions, and enforcing certain technical standards. However, the basis for designing effective policy instruments to abate air emissions is finding reliable estimates of those emissions. For the shipping sector, a debate continues about the most appropriate way to achieve its air emissions estimate. This paper contributes to this debate by proposing a new methodology that applies some of the available theories from the naval design scientific field to derive a microscopic analytical formulation of the energy produced and consumed by a ship during its trips. The methodology proposed is applied to evaluations of potential savings in energy and emissions by adjusting the speed–acceleration profile of ships in port. Results achieved confirm the power of the methodology and open its application to other case studies. They also highlight an aspect usually neglected in the literature: the impact of ships' activities in port on the environment. The simple exercises performed show clearly the relevance of the issue. They are also able to show that better management of ships' movements in port may produce significant environmental benefits.

Damage Control System: an Application for Ship Safety and Security

A crucial application in naval field called Damage Control System (DCS) is the focus of this paper. DCS is an information-retrieval and equipment-control system that allows ship personnel to detect, analyze, and handle various types of situations which are hazardous for shipboard safety. The DCS is embedded in the Integrated Platform Management System (IPMS) and developed by researches of, Apphia s.r.l., CCII (Centro Cultura Innovativa d'Impresa) of University of Salento and Avio S.p.A..

Prediction of the Strength of the Adhesively Bonded Joints by the Finite Elements Method

Using the Abaqus software, the goal of this work is the numerical study of the effects of the static loads on the mechanical behavior, the damage and the strength of the aluminum/aluminum and composite/composite assemblies, very much used in the naval field. For an elastic behavior of the adhesive, it is also a question of modeling the damage of the substrates in composite. This paper presents a numerical investigation on the behavior of structural adhesive bounding under quasi-static loading. It is shown the effects of the adhesive thickness, superposition length and staking lay up on the strength of the adhesively bonded joints under static tensile. A comparison between the use of aluminum and composite laminate substrates is presented and an attempt was made to find out the damage kinetic.

Time-variant assessment for adhesively bonded assemblies with non-linear behaviour in naval applications

Adhesive bonding is becoming a widely used assembling process in the naval field; it can allow great productivity, simplify design constraints and can lead, in general, to a significant weight reduction. Unfortunately, this technology is not completely mastered; parameters like the cure process, size of defects, joint adhesive thickness variations, size of parts to be assembled and non-linear behaviour of the adhesive joint, have to be considered to assess the risks and predict the service life. Moreover, for naval applications adapted state functions have to be proposed in order to take into account this variability of material properties, the time dependency of parameters like damage, solicitations or loads. Under these assumptions, time-independent reliability is insufficient to allow a pertinent-related failure probability calculation. The solution of such a problem can be given by the use of time-dependent reliability tools. This passes through coupling structural reliability software evaluation with a non-linear finite element code. This choice requires robust mechanical models able to describe the behaviour of naval structure with an acceptable numerical cost in order to perform the reliability study. This paper presents a time variant reliability approach based on the PHI2 method. Cohesive-zone models are used to model the adhesive. This choice allows limiting the numerical cost of simulations and permits us to model the non-linear behaviour of adhesive. It also presents a good compromise between numerical costs and quality of results. The damage at the interface can be modelled and it has been proven that using cohesive zone models is well suited for bonded joints as the possible degradation zone is well defined. In order to determine the cohesive zone model parameters, tests were performed. The most relevant results are presented. Different numerical results showing the feasibility of this approach for adhesively bonded assemblies are discussed and the case of a representative part of a naval structure has been studied in this paper.

Simulation of anti-roll tanks and sloshing type problems with smoothed particle hydrodynamics

We describe the work performed in the numerical simulation of passive roll-damper tanks for fishing vessels. The fluid in the tank behaves as a resonant fluid system, and this resonant behavior justifies their usage as counter-moment generators for sea waves. Although the experimental data come from the naval field, the techniques may be applied to design other tuned liquid damper and tuned sloshing damper devices. The differences with respect to other techniques arise from using the smoothed particle hydrodynamics (SPH) method to perform simulations. With SPH, it is feasible to model large free surface deformations and wave breaking. The results of the simulations have been validated with experimental tests corresponding to real configurations. Against experimental data, we compare pure quantitative physical magnitudes as moment phase lags with respect to tank movement and more qualitative ones as free surface shapes. Although large amplitude waves and breaking waves appear, they are well reproduced and the numerical values of phase lags accord to the experiments. To summarize, the results are promising but further work has yet to be done.

Anesthesia in Northern Iraq: An Audit from a Field Hospital

A Royal Naval field surgical team deployed to Iraq for 6 weeks. Seventy-one anesthetics were administered to 52 patients. The Triservice anesthetic apparatus (TSA) was used with controlled ventilation and either halothane plus trichloroethylene or isoflurane. Other techniques included spontaneous ventilation via the TSA, ketamine and midazolam, either with or without controlled ventilation, or local anesthesia. A simple modification allowed preoxygenation with 100% oxygen. Controlled ventilation with air alone was usually associated with satisfactory pulse oximetry and oxygen economy. Isoflurane was not significantly hypotensive and recovery was more rapid than with halothane/trichloroethylene. Drawover techniques with controlled ventilation were satisfactory for children as small as 6.5 kg. Overnight ventilation was instituted on three occasions, and it was found that a simple positive end expiratory pressure system could be applied to the Laerdal valve. Pulse oximetry, ECG, and automatic arterial pressure monitoring facilities were used. The total drug expenditure for all 71 anesthetics was only $178.

Leadership Succession and Security in the Philippines

The election of Fidel Ramos as President of the Philippines com pleted the full restoration of democracy in that country. While democratic institutions are in place, they are not conducive to ensuring effective and efficient administration which the Philip pines requires if it is to return to economic health. One major reason for this paralysis is the fear that the country would revert back to dictatorship or authoritarianism. Thus, while every Filipino recognizes the need to have a strong President, the public also feels that the checks and balances in the system must be preserved, lest the country lapses back into authoritarianism. Compounding this is the Marcos legacy, which has not been totally erased. New elites, who have different agendas, have also emerged. This, together with the need to preserve democracy at all costs, are hampering the government's efforts to revive the country's for tunes. While the U.S. withdrawal from Subic Bay naval base and Clark air field has made the Philippines more vulnerable to ex ternal attacks, the threat to the country's security largely emanates from the domestic front. Rapid economic development is a crucial factor in ensuring political stability and preserving the country's security, but the Philippines can achieve this only if there is national unity.

Supporting ‘a Navy for the nineties’

The themes of flexibility, mobility, reorganisation and rationalisation recur throughout the various contributions on Logistics in this edition. The Royal Navy's preoccupation is no different in striving for responsive, sustainable and cost effective logistics support where it is needed—close to the front line. This article therefore covers four selected topics which illuminate the main developments: the formation of the new Naval Support Command; the Fleet Sup’ port restructuring programme; naval operational logistics (including support to amphibious forces); and future technical developments in the naval logistics field.

Use of Artificial Intelligence to Evalutate Diesel Engine Efficiency

Thanks to the experience acquired in the industrial diagnosis field, SEPA has developed a system that exploits the use of Artificial Intelligence to find out eventual faults and malfunctions of a Diesel Engine. The system makes some tests on the engine, in the normal conditions of operations and installation, without the need of any special test equipment. The collected data are transmited to the expert system, that duly instructed analyzes the received data and gives some information about the status of the engine, proposing, if necessary, one or more repairing or maintenance actions. This type of diagnosis allows non-specialist people to quickly discover the faults and to execute repainng. SEPA system is easily adaptable lo any kind of engine, in particular, it could Find some interesting applications in naval field, to prevent the engine faults and, in any case, to intervene quickly when a lault happens. In this paper we want to analyze the system designed by SEPA, to describe how the expert system works (the type of rules which it is based on and the process to arrive to the correct diagnosis) and finally lo examine a possible application of this system in the naval automation field.