Submarine Applications Research Articles

Investigation of laser-induced plasma characteristics in bulk water under different focusing arrangements.

Laser-induced breakdown spectroscopy (LIBS) has drawn more attention as a new technique for in situ detection of seawater, especially for hydrothermal areas. In order to evaluate the focusing geometry effect on laser-induced plasma in bulk water, four focusing arrangements were tried out with a single lens as well as with a double-lens combination. We demonstrated that, for the same transmission distance in water, the double-lens combination with shorter effective focal length generated more condensed plasma, as shown by the spectroscopic and fast imaging results. Accordingly, the moving breakdown phenomenon significantly decreased with well-improved LIBS intensity, signal-to-noise ratio, and stability. The plasma emissions evidently attenuated along the laser transmission due to the strong absorption effect of the water medium. Based on the acquired results, the performance of a practical detection window was evaluated by combining the regular lens with a customized lens-shaped optical window, and a positive outcome was also reached. The obtained results suggested that improved LIBS detection could be easily achieved via settling another lens window to LIBS system, which is considered helpful for better in situ submarine application.

Probabilistic cost prediction for submarine power cable projects

It is estimated that Europe alone will need to add over 250,000km of transmission capacity by 2050, if it is to meet renewable energy production goals while maintaining security of supply. Estimating the cost of new transmission infrastructure is difficult, but it is crucial to predict these costs as accurately as possible, given their importance to the energy transition. Transmission capacity expansion plans are often founded on optimistic projections of expansion costs. We present probabilistic predictive models of the cost of submarine power cables, which can be used by policymakers, industry, and academia to better approximate the true cost of transmission expansion plans. The models are both generalizable and well-specified for a variety of submarine applications, across a variety of regions. The best performing statistical learning model has slightly more predictive power than a simpler, linear econometric model. The specific decision context will determine whether the extra data gathering effort for the statistical learning model is worth the additional precision. A case study illustrates that incorporating the uncertainty associated with the cost prediction to calculate risk metrics - value-at-risk and conditional-value-at-risk - provides useful information to the decision-maker about cost variability and extremes.

Underwater superoleophobicity, anti-oil and ultra-broadband enhanced absorption of metallic surfaces produced by a femtosecond laser inspired by fish and chameleons.

Reported here is the bio-inspired and robust function of underwater superoleophobic, anti-oil metallic surfaces with ultra-broadband enhanced optical absorption obtained through femtosecond laser micromachining. Three distinct surface structures are fabricated using a wide variety of processing parameters. Underwater superoleophobic and anti-oil surfaces containing coral-like microstructures with nanoparticles and mount-like microstructures are achieved. These properties of the as-prepared surfaces exhibit good chemical stability when exposed to various types of oils and when immersed in water with a wide range of pH values. Moreover, coral-like microstructures with nanoparticle surfaces show strongly enhanced optical absorption over a broadband wavelength range from 0.2–25 μm. The potential mechanism for the excellent performance of the coral-like microstructures with a nanoparticle surface is also discussed. This multifunctional surface has potential applications in military submarines, amphibious military aircraft and tanks, and underwater anti-oil optical counter-reconnaissance devices.

Design and Performance Analysis of Double Stator Axial Flux PM Generator for Rim Driven Marine Current Turbines

This paper presents the design and performance analysis of double stator axial flux permanent magnet generators for rim-driven marine current turbines (MCT). In submarine applications, drive train reliability is a key feature for reducing maintenance requirements. Rim-driven, direct-drive, multistator generators can therefore be an interesting solution to improve reliability. In this context, the work presented here focuses on the design of a double-stator, axial flux, permanent magnet (PM) generator as a rim-driven, direct-drive, multistator generator. The models, specifications and an optimization procedure that facilitate the preliminary design of these kinds of generators for rim-driven marine turbines are presented. Validation with finite element computations and a performance analysis for a particular design of rim driven generators are conducted. The results obtained highlight some designs issues associated with PM generators for rim driven marine turbines. To assess the effectiveness of the double stator axial flux PM generator, a comparison with a surface mounted radial flux PM generator design for rim marine turbines is carried out. The comparison shows that the double stator axial flux generator has a better cooling characteristic and a reduced active parts cost and mass than the radial flux PM generator.

How to quantify and predict long term multiple stress operation: Application to Normally-Off Power GaN transistor technologies

The present paper is implementing a numerical application of the Boltzmann–Arrhenius–Zhurkov (BAZ) model and relates to the statistic reliability model derived from the Transition State Theory paradigm. It shows how the quantified tool can be applied to determine the associated effective activation energy. The unified multiple stress reliability model for electronic devices is applied to Normally-Off Power GaN transistor technologies to quantify and predict the reliability figures of this electronic type of product when operating under multiple stresses in an embedded system operating under such harsh environment conditions as set for Aerospace, Space, Nuclear, Submarine, Transport or Ground application.

Diesel autothermal reforming with hydrogen peroxide for low-oxygen environments

Abstract To operate fuel cells effectively in low-oxygen environments, such as in submarines and unmanned underwater vehicles, a hydrogen source with high hydrogen storage density is required. In this paper, diesel autothermal reforming (ATR) with hydrogen peroxide as an alternative oxidant is proposed as a hydrogen production method. Diesel fuel has higher hydrogen density than metal hydrides or other hydrocarbons. In addition, hydrogen peroxide can decompose into steam and oxygen, which are required for diesel ATR. Moreover, both diesel fuel and hydrogen peroxide are liquid states, enabling easy storage for submarine applications. Hydrogen peroxide exhibited the same characteristics as steam and oxygen when used as an oxidant in diesel reforming when pre-decomposition method was used. The thermodynamically calculated operating conditions were a steam-to-carbon ratio (SCR) of 3.0, an oxygen-to-carbon ratio (OCR) of 0.5, and temperatures below 700 °C to account for safety issues associated with hydrogen peroxide use and exothermic reactions. Catalytic activity and stability tests over Ni–Ru (19.5–0.5 wt.%)/Ce0.9Gd0.1O2−x were conducted using various diesel compounds. Furthermore, long-term diesel ATR tests were conducted for 200 h using Korean commercial diesel. The degradation rate was 3.67%/100 h without the production of ethylene.

CHOICE OF EFFECTIVE MATERIALS FOR A HYDROTECHNICAL CONCRETE

Purpose. Determination of rational correlation of materials is the important stage of technology of hydrotechnical concrete in composition a concrete mixture. Properties of concrete mix are determined both by granulometric composition and the volume and properties of the binder. Methodology. He structure of cement-sandy solution of enhanceable mobility is investigational experimentally for a pipeline transport. Findings. It is set on the basis of analysis of the conducted researches, that the receipt of hydrotechnical concrete with the set properties is possible as a result of application of the special technology of concreting with the use of high-mobile cement-sandy solution with active one micro by filling in a complex with the plasticizer modified for the terms of submarine application. Originality. Possibility of receipt of hydrotechnical concrete is well-proven with the set properties by an injection method with the use of cement-sandy mixture. Practical value. Complex of technological actions has allow ensure a reception of concretes with given characteristics for undersea working the classes B15…B25 when reducing a consumption of cement on 15 % in the comparison with the traditional technology.

Hydrides for submarine applications: Overview and identification of optimal alloys for air independent propulsion maximization

This study identifies possible alternatives in the currently use of hydrides in submarine applications in order to increase the storage capacity and, therefore, the autonomy (Air Independent Propulsion) of the boat. The study proposes a plug and play solution which requires no changes for what concerning the current propulsion system, nor the auxiliary systems of absorption and desorption of hydrogen, nor the power supply system of fuel cells. Different constraints have been taken into account, as the storage volume density, the operating conditions (pressure and temperature), the number of charge and discharge cycles. Taking into account that it is desirable to maintain the set-up of the actual systems (for what concerning the spaces, the pressure and temperature) the solution obtained in the present study ranges in between the following target values: 120 g/dm3 for the storage capacity in volume; 20–50 °C for the operating temperature, 2–3 bar for the hydrogen desorption pressure and 150 charge and discharge cycles that can ensure 5 cycles per year for 30 years. Under these constraints, a significant increase of the autonomy of the boat has been evaluated.

Power Cables and Submarine Power Cables

Power cables have been in use in underground and submarine transmission for over a hundred years. With the increased interconnection between lands and integration with power generation from offshore renewable energy, the demand for submarine power cables is getting stronger. This article discusses the differences between power cables used for land and submarine application and also investigates the impact of AC (alternating current) and DC (direct current) operation on power cable designs. Specific technical issues with submarine power cables in both AC and DC applications are highlighted and addressed. Unless otherwise indicated, the discussion in this article focuses on the transmission level, that is, 110 kV (in the mainland Europe) or 132 kV/275 kV (in the UK) and above for both AC and DC applications. However, the content of this article should largely be valid for lower voltage power cables, such as inter-array cables linking offshore wind turbines to offshore substations or distribution links across rivers or linking islands located closely to the mainland. Owing to the length limitation on text, this article has not discussed issues in relation to the technical and practical deployment of high voltage submarine power cables.

Transient Analysis and Modelling of Sixphase Asynchronous Machine

Multiphase Induction machine offers numerous advantages compared to the conventional three phase induction machine. Among the different types, the six-phase induction machine is most common, due to the flexibility in converting a three phase to six phase. By splitting the phase belt of a three phase induction machine, a six-phase induction machine is realized. The areas of application of multiphase (>3) machines are enormous, mostly where reliability is paramount. This paper presents the analysis, modeling and simulation of a 5Hp, 50HZ, 4 pole, 24 slots asymmetrical six-phase induction machine for submarine application. With the help of MATLAB software, the models developed are simulated and results in the form of computer traces of the dynamic performance of the machine at start-up are presented and discussed. This investigation shows that the replacement of three phase with a six phase machine is both technically and economically advantageous.

Study on governing parameters of thermal history during underwater friction stir welding

Underwater friction stir welding (FSW) could widely extend the submarine applications of solid-state welding methods. Since, in the case of underwater FSW, the temperature field exhibits profound effects on the acquired weld properties, studying the corresponding governing parameters is of high priority. With this end in view, in order to explicate the heat generated by the FSW tool, the applied forces on the FSW tool, as the unknown parameters in the heat generation equation, are obtained. Subsequently, the heat transfer of the surrounding fluid, which dictates the heat transfer through the workpiece is investigated. The results reveal that upon comparison to FSW in air medium, both translational and axial forces considerably increase leading to greater heat generated by the underwater FSW tool. However, the peak temperature in each point during underwater welding declines dramatically (40 %) compared to the in-air welding, which can be attributed to the extreme boiling heat transfer of water on both the workpiece and FSW tool. This behavior may be the main reason for the acquired mechanical properties of the underwater-welded AA7075-T6 plates as a precipitating hardening alloy. The mentioned heat transfer is non-uniform over the workpiece and comprises different types including nucleation and transition boiling as well as free convection. Furthermore, the study of the mechanical characteristics revealed that underwater welding leads to joints with more strength and lower ductility compared to those obtained by in-air welding.

Negative impedance shunted electromagnetic absorber for broadband absorbing: experimental investigation

The traditional tuned mass absorber is widely employed to control the vibration of a primary structure by transferring the vibrating energy to the absorber. However, the working band of the absorber is very narrow, which limits the application of broadband vibration control. This study presents a novel broadband electromagnetic absorber by first introducing two negative impedance shunts to improve broadband damping of the absorber. The electromagnetic absorber is modeled, and the corresponding electromagnetic coupling coefficient is tested. A cantilever beam is employed to verify the broadband vibration absorption of the negative resistance (NR) shunted electromagnetic absorber (NR absorber) and the negative inductance NR shunted electromagnetic absorber (NINR absorber). The governing equations of the beam with two absorbers are derived, and the experiments are set up. The results point out that the NR and NINR absorbers can attenuate the broadband vibration. The proposed absorbers do not need the feedback system and the real-time controller compared to the active absorber; hence, they have great application potential in aerospace and in submarine applications, as well as in civil and mechanical engineering.

PROBLEMS OF MANAGEMENT BY TECHNOLOGICAL PROPERTIES OF HYDROTECHNICAL CONCRETE MIXTURES

conditions of displacement process control is the highest possible disagglomeration of particles, reduction of mix viscosity and increase of its homogeneity. Methodology. He structure of cement-sandy solution of enhanceable mobility is investigational experimentally for a pipeline transport. Findings. In work are explored particularities of structurisation of cement stone with the filler and rolling additives in conditions of undersea repeating over and over again. It is set on the basis of analysis of the conducted researches, that the receipt of hydrotechnical concrete with the set properties is possible as a result of application of the special technology of concreting with the use of highmobilecement-sandy solution with active one micro by filling in a complex with the plasticizer modified for the terms of submarine application. Originality. Experimental confirm efficiency of using highrolling cement-sandy dissolve for injecting intercom spaces large filling under undersea concreting. Practical value. Conduct structure studies of undersea concrete and is motivated technology injecting method of undersea concreting.

An Investigation on Strength Degradation of Gfrp Laminates Under Environmental Impact

The usage and replacement of conventional materials with polymer co mposite materials for engineering applications is always questioned by the end user, unless otherwise supported by the authentic published research. The reinforcement materials are highly hygroscopic; the matrix material provides protection to the reinforcement. Since the edges of composite components and surface are exposed to environment, water mo lecules travel along the reinforcement, which can damage the interfacial bonding, further the performance of the composite laminate may get affected. In this scenario the investigation related to this aspect, requires quantitative assessment which is carried out to estimate the damage associated by accelerated simu lation of the real time situation provides information to ext rapolate the effects of the mo isture associated damage to the composite laminate. In this present work an attempt has been made in establishing the investigation procedure to estimate the influence of mo isture absorption on strength degradation coupled with temperature. To estimate the life cycle time of poly mer co mposite components such as marine boats and components related to submarine applicat ions. Fro m the test results, it is established reduced that the tensile strength and flexural modulus were reduced significantly, of the specimens subjected to water soaking and varying temperature.

Development of Cu2+- and/or phosphonium-based polymeric biocidal materials and their potential application in antifouling paints

The synthesis and characterization of a series of biocidal polymeric materials for potential antifouling submarine applications are presented. The polymeric backbone of these materials contains anionic units, such as styrene sulfonate, and/or acrylate or maleate units. The hydrophobic/hydrophilic nature of these polymers was, furthermore, tuned through copolymerization with hydrophobic units, such as vinyl acetate or styrene. The biocidal species, Cu2+ ions and/or phosphonium cations, were incorporated through electrostatic and/or coordination interactions, depending on the nature of the polymeric backbone. It was observed that the release of Cu2+ ions in water from the Cu2+-containing materials is controlled by the hydrophobic/hydrophilic balance of the polymeric backbone. The prepared biocidal polymeric materials were incorporated into two paint formulations, based on a rosin or a vinylic matrix. The erosion properties of the biocidal paints under accelerated laboratory conditions were evaluated using scanning electron microscopy. It is found that the antifouling performance is related to the release of biocidal species. The most efficient materials are those containing Cu2+ ions or combining both Cu2+ and phosphonium cations.

Performance Study of a 980 nm GaAs Based Laser Diode Chip in a Moisture Condensing Environment

This paper presents a performance study done on a semiconductor laser diode in a moisture condensing environment. Devices with laser diodes are used in a wide variety of electronic applications and in the various climatic conditions. The motivation behind this study is a common environmental exposure, where a device using a laser diode is brought into a relatively humid building from a dry, cold, outside environments. Under such conditions, condensation occurs on various components of the device, including the diode, which could affect the laser output power. Device performance could be affected since the laser diode and the lens are susceptible to degradation due to such repetitive condensation conditions. The test vehicle chosen for this study was an optoelectronic package using a 980 nm laser diode. These are used in products for a broad range of markets, including data communications, aerospace, material processing, scientific, and defense industries [Pliska et al., "Wavelength Stabilized 980nm Uncooled Pump Laser Modules for Erbium-Doped Fiber Amplifiers," Opt. Lasers Eng., 43, pp. 271–289; Righetti, 1996, “Amplifiers Pumped at 980 nm in Submarine Applications,” European Conference on Optical Communication, Vol. 3, pp. 75–80; Pfeiffer et al., 2002, "Reliability of 980 nm Pump Lasers for Submarine, Long-haul Terrestrial, and Low Cost Metro Applications," Optical Fiber Communication Conference and Exhibit, pp. 483–484]. These products may be used in environmental conditions that could result in condensation within the product. A hermetic package could address this concern, but it is an expensive option. Nonhermetic packaging for the laser component could help to lower the cost of these devices; however, these packages have important failure mechanisms that are a potential concern. Prior research reported performance studies conducted on similar packages at elevated temperature, humidity, and power conditions using accelerated tests [Pfeiffer et al., 2002, "Reliability of 980 nm Pump Lasers for Submarine, Long-haul Terrestrial, and Low Cost Metro Applications," Optical Fiber Communication Conference and Exhibit, pp. 483–484; Park and Shin, 2004, “Package Induced Catastrophic Mirror Damage of 980nm GaAs High Power Laser,” Mater. Chem. Phys., 88(2-3), pp. 410–416; Fukuda et al., 1992, “Reliability and Degradation of 980nm InGaAs/GaAs Strained Quantum Well Lasers,” Qual. Reliab. Eng., 8, pp. 283–286]. However, studies conducted that specifically addressed condensation measurements have not been previously reported. Hence, an attempt was made to study package performance with condensation, to address the identified concern for the current package. A test method based on a military standard specification was used for this purpose. Elevated temperature and humidity (without condensation) were found to affect the laser power. These were characterized to isolate the effect of condensation alone. The package was subjected to repetitive condensing cycles and laser output power was recorded as a function of time, temperature and humidity. The variation in laser output power due to condensation was observed and quantified. Results showed a temporary power degradation of approximately 5% with condensation. This was a repeatable effect throughout the test time. Visible water droplets were found in various areas of the package after the test cycle. This could lead to potential failure mechanisms during the device life time.

Mapping the magnetic susceptibility and electric conductivity of marine surficial sediments by benthic EM profiling

Distribution, accumulation, and diagenesis of surficial sediments in coastal and continental shelf systems follow complex chains of localized processes and form deposits of great spatial variability. Given the environmental and economic relevance of ocean margins, there is growing need for innovative geophysical exploration methods to characterize seafloor sediments by more than acoustic properties. A newly conceptualized benthic profiling and data processing approach based on controlled-source electromagnetic (CSEM) imaging permits to coevally quantify the magnetic susceptibility and the electric conductivity of shallow marine deposits. The two physical properties differ fundamentally insofar as magnetic susceptibility mostly assesses solid particle characteristics such as terrigenous or iron mineral content, redox state, and contamination level, while electric conductivity primarily relates to the fluid-filled pore space and detects salinity, porosity, and grain-size variations. We develop and validate a layered half-space inversion algorithm for submarine multifrequency CSEM with concentric sensor configuration. Guided by results of modeling, we modified a commercial land CSEM sensor for submarine application, which was mounted into a nonconductive and nonmagnetic bottom-towed sled. This benthic EM profiler Neridis II achieves 25 soundings/second at 3–4 knots over continuous profiles of up to a hundred kilometers. Magnetic susceptibility is determined from the 75 Hz in-phase response (90% signal originates from the top 50 cm), while electric conductivity is derived from the 5 kHz out-of-phase (quadrature) component (90% signal from the top 92 cm). Exemplary survey data from the north-west Iberian margin underline the excellent sensitivity, functionality, and robustness of the system in littoral (∼0–50 m) and neritic (∼50–300 m) environments. Susceptibility versus porosity crossplots successfully identify known lithofacies units and their transitions. All presently available data indicate an eminent potential of CSEM profiling for assessing the complex distribution of shallow marine surficial sediments and for revealing climatic, hydrodynamic, diagenetic, and anthropogenic factors governing their formation.

Degradation of rubber to metals bonds during its cathodic delamination, validation of an artificial ageing test

Rubber-metal assemblies used for submarine applications are often associated to cathodic protection which can lead to cathodic disbonding of the polymer/metal interface. The degradation mechanisms of polychloroprene/epoxy adhesive/copper–aluminium substrate systems associated to an accelerated ageing test are compared to the degradations resulting from natural ageing conditions in the Mediterranean sea. From destructives tests, a kinetic in four steps is identified for both ageing conditions. This kinetic is confirmed by Electrochemical Impedance Spectroscopy data during ageing. In order to further identify the failure mode, the disbonded surfaces on polymer and steel sides are analyzed using SEM and FTIR. Both ageing conditions present the same type of degradation which validates the fact that the accelerated ageing protocol reproduces the natural conditions. The chemical transformations in delaminated epoxy are very similar to the chemical transformation in epoxy coatings under high energy electron-beam irradiation. However, bidendate metal carboxylates rather than carboxylic acid chain ends are the main oxidation products due to the alkaline environment at the coating-metal interface. It was shown that the metal/polymer interface is not destroyed by an alkaline attack but by a strongly oxidative attack caused by the intermediates of the oxygen reduction.

A look at design and application of fuel cell systems

Over the past few years, the direct conversion of chemical into electrical energy via fuel cells has been at the center of attention of electrochemical research and technology development. This is due not only to the complexity of fuel cell reactions and the general awareness of the technological potential of fuel cells but is also a result of society's strive towards developing environmentally-friendly power generation. In the reaction between hydrogen and oxygen for example, the only chemical product is water. The fuel cell, initially developed in the sixties as an on-board power supply unit for spacecraft, has now found new applications in powering submarines, in decentralized power supply systems, in portable charging docks for small electronics and in sensor technology. In the quest for a highly efficient, emission-free drive system, the development of mobile automotive fuel cell units is proving to be quite promising. Fuel cell technology constitutes a highly varied field which extends from available fuels and their processing, through the fundamentals of electrochemical processes, especially electro-catalysis, right to the numerous new concepts in systems technology for complete fuel cell aggregates including the control of gas, water and heat management. Many publications now appear annually in this field. The number of patent applications, especially from the industrial sector, has also risen over the past ten years. However, this paper is related to the design and application of fuel cell systems. Key words: Design, fuel, cell systems, power generation.

Cathodic Recirculation System Using a Dual-ejector to Improve Oxygen Utilization of a Submarine Fuel Cell

In terms of the system efficiency, it is very useful to apply the ejector into the fuel recirculation system of a fuel cell system since the ejector needs no parasitic power to operate. Since the conventional automotive fuel cell use hydrogen and air as their fuel, the only hydrogen is needed to be recirculated for the better fuel efficiency. On the other hand, the submarine fuel cell needs both hydrogen and oxygen recirculation systems because the submarine drives under the sea. In particular, the cathodic recirculation has to meet the tougher target since the oxygen based pressurized stack generally used in the submarine applications generates the significant amount of the water in the stack during the operation. Namely, the oxygen utilization has designed less than 50% in the whole operating range for the better exhausting of the generated waters. And thereby in terms of the oxygen utilization, the entrainment ratio of the ejector should be more than 1 within the whole operating range. However, the conventional ejector using a constant nozzle can not afford to satisfy the mentioned critical requirement. To overcome the problem, the dual-ejector and its control strategy are designed. The performance of the proposed dual-ejector is verified by the experiments based on the real operating conditions of the target submarine system. Furthermore, the proposed design method can be used for the other fuel recirculation system of a large-scale fuel cell system with the critical requirement of the fuel utilization.