The budgetary constraints for the Brazilian Navy (BN) have caused several negative effects, resulting in an undersized fleet, decreasing the capacity to protect marine oil and natural gas fields, ...combat marine pollution from ships, and monitor other illegal activities at sea and inland waters. This paper aims to choose a medium-sized warship to be built by the BN, through the application of the Analytic Hierarchy Process (AHP) method. After a bibliometric study on Multiple-Criteria Decision-Making (MCDM), the AHP was chosen as the most appropriate method for the proposed case study. We analyzed three ship projects with regard to nine operational and economic criteria, taking into account the evaluations of BN officers with recognized experience and knowledge in military operations. We also introduced a sensitivity analysis based on the relationship between standard deviation and mean scores in order to verify and increase the reliability of the ranking. As a result, the methodology suggested that the best option is to build a brand-new ship with more significant modernizations to provide for the operational needs of the BN.
•Six DOFs of warship under different sea states can be efficiently calculated by strip theory.•Random reflection coefficients close to real environment can be obtained by empirical formula and Monte ...Carlo method.•Accurately predicting echo strength of warships coupled with undulating sea surfaces.•Echo strength of warship with wave dynamic coupling conforms to the statistical regularity of Chi-Square distribution.
The echo signatures of a warship can be tracked by an underwater weapon equipped with an active sonar system. However, the dynamics of undulating sea surfaces and the influence of sound reflection result in a lack of sufficiently detailed feature studies. A hybrid method is proposed to predict the acoustic scattering of warships under time-varying undulating sea surfaces, considering the multiple reflection effects of the sea surface. Specifically, the echo strength (ES) of warships is predicted under various wave spectra by coherently summing the echoes from different paths using the Four-Path method. This predictive process involves constructing a 3D warship model, acquiring the six degrees of freedom (DOFs) motion attitude, and determining the sea surface reflection coefficient under different sea state parameters. Furthermore, a statistical model is proposed for the ES of undulating interface targets. To validate the effectiveness of this hybrid method, an acoustic scattering echo experiment was conducted in a towing tank under wave-making conditions. The results demonstrate that the average error of ES between the prediction and experimentation is less than 2 dB within the detection frequency range of 120 kHz to 180 kHz. With the statistical model, the results also indicate that the ES over time conforms to the statistical regularity of the chi-square distribution. Additionally, the mean value of ES and the value of double degree of freedom k align well. In summary, this work represents a systematic effort to predict the ES of warships coupled with undulating sea surfaces using a new method.
This is a major new account of the Battle of Jutland, the key naval battle of the First World War in which the British Grand Fleet engaged the German High Seas Fleet off the coast of Denmark in 1916. ...Beginning with the building of the two fleets, John Brooks reveals the key technologies employed, from ammunition, gunnery and fire control, to signalling and torpedoes, as well as the opposing commanders' tactical expectations and battle orders. In describing Jutland's five major phases, he offers important new interpretations of the battle itself and how the outcome was influenced by technology, as well as the tactics and leadership of the principal commanders, with the reliability of their own accounts of the fighting reassessed. The book draws on contemporary sources which have rarely been cited in previous accounts, including the despatches of both the British and German formations, along with official records, letters and memoirs.
Being the important composition, the efficiency of information transmission system affects directly degree of system operational task. Aiming at the characteristics of warship information ...transmission efficiency evaluation multiple requirements and complex system organization application, the paper applies the method combining technique quantification model and restriction factors. Rounding single link, multiple links and marshalling operations information transmission requirements, the system structure of information transmission efficiency evaluation based on operational task is established, which can offer efficient supplication for warship communication command.
Systems engineering plays a key role in the naval sector, focusing on how to design, integrate, and manage complex systems throughout their life cycle; it is therefore difficult to conceive ...functional warships without it. To this end, specialized information systems for logistical support and the sustainability of material solutions are essential to ensure proper provisioning and to know the operational status of the frigate. However, based on an architecture composed of a set of logistics applications, this information system may require highly qualified operators with a deep knowledge of the behavior of onboard systems to manage it properly. In this regard, failure detection systems have been postulated as one of the main cutting-edge methods to address the challenge, employing intelligent techniques for observing anomalies in the normal behavior of systems without the need for expert knowledge. In this paper, the study is concerned to the scope of the Spanish navy, where a complex information system structure is responsible for ensuring the correct maintenance and provisioning of the vessels. In such context, we hereby suggest a comparison between different one-class techniques, such as statistical models, geometric boundaries, or dimensional reduction to face anomaly detection in specific subsystems of a warship, with the prospect of applying it to the whole ship.
ObjectiveThe prediction of supporting resources has always been a focus and difficulty of naval ship comprehensive support. In this paper, a prediction model and method are proposed for the support ...needs of naval ship maintenance docks. MethodThe Markov process is introduced and applied to the prediction of ship dock demand. By analyzing the system characteristics of ship dock use, a Markov forecasting model and evaluation index of dock demand are established, and the validity of the prediction method is verified by case analysis. ResultsThe calculation example shows that the prediction model can better reflect the influence of ship maintenance intensity and the number of docks on the system state, and the optimal dock requirements reflected by the evaluation index are in good agreement with the actual engineering. ConclusionThe prediction model of ship repair dock demand proposed in this paper can better reflect the physical process and engineering practice, and provide theoretical support for decision analysis, giving it good practical significance.
Large gatherings of people on cruise ships and warships are often at high risk of COVID-19 infections. To assess the transmissibility of SARS-CoV-2 on warships and cruise ships and to quantify the ...effectiveness of the containment measures, the transmission coefficient (β), basic reproductive number (R0), and time to deploy containment measures were estimated by the Bayesian Susceptible-Exposed-Infected-Recovered model. A meta-analysis was conducted to predict vaccine protection with or without non-pharmaceutical interventions (NPIs). The analysis showed that implementing NPIs during voyages could reduce the transmission coefficients of SARS-CoV-2 by 50%. Two weeks into the voyage of a cruise that begins with 1 infected passenger out of a total of 3,711 passengers, we estimate there would be 45 (95% CI:25-71), 33 (95% CI:20-52), 18 (95% CI:11-26), 9 (95% CI:6-12), 4 (95% CI:3-5), and 2 (95% CI:2-2) final cases under 0%, 10%, 30%, 50%, 70%, and 90% vaccine protection, respectively, without NPIs. The timeliness of strict NPIs along with implementing strict quarantine and isolation measures is imperative to contain COVID-19 cases in cruise ships. The spread of COVID-19 on ships was predicted to be limited in scenarios corresponding to at least 70% protection from prior vaccination, across all passengers and crew.
Warships play an important role in the modern sea battlefield. Research on the line spectrum features of warship radio noise signals is helpful to realize the classification and recognition of ...different types of warships, and provides critical information for sea battlefield. In this paper, we proposed a novel linear spectrum frequency feature extraction technique for warship radio noise based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), duffing chaotic oscillator (DCO), and weighted-permutation entropy (W-PE). The proposed linear spectrum frequency feature extraction technique, named CEEMDAN-DCO-W-PE has the following advantages in comparison with other linear spectrum frequency feature extraction techniques; (i) as an adaptive data-driven algorithm, CEEMDAN has more accurate and more reliable decomposition performance than empirical mode decomposition (EMD) and ensemble EMD (EEMD), and there is no need for presetting parameters, such as decomposition level and basis function; (ii) DCO can detect the linear spectrum of narrow band periodical warship signals by way of utilizing its properties of sensitivity for weak periodical signals and the immunity for noise; and (iii) W-PE is used in underwater acoustic signal feature extraction for the first time, and compared with traditional permutation entropy (PE), W-PE increases amplitude information to some extent. Firstly, warship radio noise signals are decomposed into some intrinsic mode functions (IMFs) from high frequency to low frequency by CEEMDAN. Then, DCO is used to detect linear spectrum of low-frequency IMFs. Finally, we can determine the linear spectrum frequency of low-frequency IMFs using W-PE. The experimental results show that the proposed technique can accurately extract the line spectrum frequency of the simulation signals, and has a higher classification and recognition rate than the traditional techniques for real warship radio noise signals.
In addition to endangering sea traffic, cable routes, and wind farms, sunken warship wrecks with dangerous cargo, fuel, or munitions on board may emerge as point sources for environmental damage. ...Energetic compounds such as TNT (which could leak from these munitions) are known for their toxicity, mutagenicity, and carcinogenicity. These compounds may cause potential adverse effects on marine life via contamination of the marine ecosystem, and their entry into the marine and human food chain could directly affect human health. To ascertain the impending danger of an environmental catastrophe posed by sunken warships, the North Sea Wrecks (NSW) project (funded by the Interreg North Sea Region Program) was launched in 2018. Based on historical data (derived from military archives) including the calculated amount of munitions still on board, its known location and accessibility, the German World War II ship “Vorpostenboot 1302” (former civilian name - “JOHN MAHN”) was selected as a case study to investigate the leakage and distribution of toxic explosives in the marine environment. The wreck site and surrounding areas were mapped in great detail by scientific divers and a multibeam echosounder. Water and sediment samples were taken in a cross-shaped pattern around the wreck. To assess a possible entry into the marine food chain, caged mussels were exposed at the wreck, and wild fish (pouting), a sedentary species that stays locally at the wreck, were caught. All samples were analyzed for the presence of TNT and derivatives thereof by GC–MS/MS analysis. As a result, we could provide evidence that sunken warship wrecks emerge as a point source of contamination with nitroaromatic energetic compounds leaking from corroding munitions cargo still on board. Not only did we find these explosive substances in bottom water and sediment samples around the wreck, but also in the caged mussels as well as in wild fish living at the wreck. Fortunately so far, the concentrations found in mussel meat and fish filet were only in the one-digit ng per gram range thus indicating no current concern for the human seafood consumer. However, in the future the situation may worsen as the corrosion continues. From our study, it is proposed that wrecks should not only be ranked according to critical infrastructure and human activities at sea, but also to the threats they pose to the environment and the human seafood consumer.
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•Warship wrecks with munitions on board emerge as point source for environmental risk.•The World War II ship “Vorpostenboot 1302” (“JOHN MAHN”) serves as our case study.•Energetic chemicals leak out into the marine environment around the wreck.•Fish and mussels at the wreck take up these toxic and carcinogenetic chemicals.
Introduction. The military readiness of the naval personnel serving on a warship requires a high level of physical health and fitness which is considered a given capability, regardless of the service ...they serve. The purpose of this study was to investigate the effects of a weight training program (WTP) on the physical fitness of Greek naval cadets during a training trip on a warship. Material & Methods. The sample consisted of 21 male Greek cadets of the Hellenic Naval Academy (HNA) (age: 21.0 ± 0.83 years, height: 177.9 ± 6.9cm, body mass: 78.2 ± 7.1kg). The cadet team that participated for four weeks on the trip performed 20 training sessions lasting 60-80 min each, five times a week. The measurements of the participants before and after 4 weeks of a weight exercise training program were related to body mass (BM), body fat percentage (% BF), body mass index (BMI), number of sit-ups (SU1) and push-ups (PU1) done in one minute, one repetition maximum (1RM) in a squat (SQ) and bench press (BP), and the 30m run and 5m rope climb. Results. The results of the study showed that the WTP did not affect BM (t20 = -0.412, p = .685 > .05) and BMI (t20 = -0.477, p = .639>.05). Respectively, no significant difference was observed in %BF in all cadets between the measurements (t20 = -0.962, p > .05). The number of PU1 significantly increased by 10.82% (t20 = -4.191, p < .01). The SU1 significantly increased by 9.34% (t20 = -4.613, p < .01). The 1RM increased on BP by 5.71% (t20 = -5.769. p < .01) and SQ by 7.73% (t = 20, p < .01). The time on 30m sprint decreased by 1.33% (t20 = 7.640, p < .01) and for 5m rope climb decreased by 3.15% (t20 = 6.663, p < .01). Conclusion. The results of this study showed that it is necessary for the naval cadets to follow a WTP during their trips in the sea on a warship to increase their physical condition/fitness and sustain their body composition.
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