Showing papers by "Naval Surface Warfare Center published in 2011"

Economic impact of biofouling on a naval surface ship

Abstract: In the present study, the overall economic impact of hull fouling on a mid-sized naval surface ship (Arleigh Burke-class destroyer DDG-51) has been analyzed. A range of costs associated with hull fouling was examined, including expenditures for fuel, hull coatings, hull coating application and removal, and hull cleaning. The results indicate that the primary cost associated with fouling is due to increased fuel consumption attributable to increased frictional drag. The costs related to hull cleaning and painting are much lower than the fuel costs. The overall cost associated with hull fouling for the Navy's present coating, cleaning, and fouling level is estimated to be $56M per year for the entire DDG-51 class or $1B over 15 years. The results of this study provide guidance as to the amount of money that can be reasonably spent for research, development, acquisition, and implementation of new technologies or management strategies to combat hull fouling.

Experience from SIMMAN 2008—The First Workshop on Verification and Validation of Ship Maneuvering Simulation Methods

Abstract: The SIMMAN 2008 workshop was held in Copenhagen, Denmark in April 2008. The purpose of the workshop was to benchmark the prediction capabilities of different ship maneuvering simulation methods including systems- and CFD-based methods through systematic quantitative comparisons and validation against EFD data for tanker (KVLCC), container ship (KCS), and surface combatant (5415) hull form test cases. For the KVLCC test case, two stern shape variants named KVLCC1 and KVLCC2 giving different instability loops were included. Free model test data was compared with systems-based methods and CFD for specified free maneuvers. Some of the systems-based methods used provided PMM and CMT data, and two used CFD instead. CFD-based methods were used to simulate forced motions and were compared with PMM/CMT model test data. The submissions were blind in the sense that the benchmark model test data was not provided prior to the workshop, unless data was required as input to the simulation method. A total of 64 submissions were received for the free maneuver simulations, which included a wide range of the state-of-the-art methods in use today, such as PMM- and CMT-based methods, CFD-based methods, system identification, neural network tools and various empirical methods. For the forced motion simulations a total of 16 submissions were received, comprising different CFD-based methods such as RANS, URANS, and DES. This paper gives an overview of hulls, model tests, test cases, submissions, comparison results as well as the most important observations and conclusions.

DBX-1 – A Lead Free Replacement for Lead Azide

Abstract: Efforts directed towards creating new environmentally friendly replacements for existing primary explosives have resulted in development of copper(I) 5-nitrotetrazolate (DBX-1). The chemical and physical properties of this material have been extensively investigated and it appears that DBX-1 is a suitable drop-in replacement for lead azide in a variety of ordnance applications. DBX-1 is easily prepared, has excellent thermal stability and has safety and performance properties which are equivalent to or exceed those for lead azide. A program to qualify DBX-1 for military use per NAVSEAINST 8020.5C has recently been completed and data has been forwarded to NSWC-IH for submission to Naval Sea Systems Command.

Transmit–Receive Duplexing Using Digital Beamforming System to Cancel Self-Interference

Abstract: A near-field cancellation duplexing system is demonstrated using multiple coordinated transceivers with symmetrically arranged antenna elements and a digital backend for baseband waveform phase and amplitude weighting controls. By adapting weights of multiple transmit elements, coupled interference at receiver elements deconstructively interferes, providing up to 50 dB of additional isolation over the coupling of a single transmitter to a receiving element. Bandwidth considerations of the array are presented. It is shown that uncorrelated transmit noise from multiple transmitters can be removed through tunable filtering or through adaptive beamforming of multiple receiving elements, both providing an additional 30-40 dB of interference reduction that is tunable over the frequency range of the system.

Toward real-time particle tracking using an event-based dynamic vision sensor

Abstract: Optically based measurements in high Reynolds number fluid flows often require high-speed imaging techniques. These cameras typically record data internally and thus are limited by the amount of onboard memory available. A novel camera technology for use in particle tracking velocimetry is presented in this paper. This technology consists of a dynamic vision sensor in which pixels operate in parallel, transmitting asynchronous events only when relative changes in intensity of approximately 10% are encountered with a temporal resolution of 1 μs. This results in a recording system whose data storage and bandwidth requirements are about 100 times smaller than a typical high-speed image sensor. Post-processing times of data collected from this sensor also increase to about 10 times faster than real time. We present a proof-of-concept study comparing this novel sensor with a high-speed CMOS camera capable of recording up to 2,000 fps at 1,024 × 1,024 pixels. Comparisons are made in the ability of each system to track dense (ρ >1 g/cm3) particles in a solid–liquid two-phase pipe flow. Reynolds numbers based on the bulk velocity and pipe diameter up to 100,000 are investigated.

Electrochemical Li-ion storage in defect spinel iron oxides: the critical role of cation vacancies

Abstract: Rechargeable lithium-ion batteries are the preferred power source for consumer electronic devices, but the cost and toxicity of many cathode materials limit their scale-up. Worldwide research efforts are addressing this concern by transitioning from conventional Co- and Ni-based intercalation hosts towards Fe- and Mn-based alternatives. The unfavorable energetics of the Fe2+/3+redox couple and limited Li-insertion capacities render the use of iron oxides impractical. We address this limitation with the defect spinel ferrite γ-Fe2O3 as a model structure for Li-ion insertion by replacing a fraction of the Fe3+ sites with highly oxidized Mo6+ to generate cation vacancies that shift the onset of Li-ion insertion to more positive potentials as well as increase capacity. In the present study, native and Mo-substituted iron oxides are synthesized via base-catalyzed precipitation in aqueous media, yielding nanocrystalline spinel materials that also exhibit short-range disorder characteristic of a proton-stabilized structure. The Mo-substituted ferrite reported herein is estimated to have ∼3× as many cation vacancies as γ-Fe2O3 with a corresponding increase in the Li-ion capacity to >100 mA h g−1 between 4.1 and 2.0 V vs.Li/Li+. This dual enhancement in capacity and insertion potential will enable these and related defect spinel ferrites to be explored as positive electrode materials for lithium batteries, while retaining the cost advantages of a material whose metal composition is still predominately iron based.

Managing the interstitials, a System of Systems framework suited for the Ballistic Missile Defense System

Abstract: Recent engineering experiences with the Missile Defense Agency (MDA) Ballistic Missile Defense System (BMDS) highlight the need to analyze the BMDS System of Systems (SoS) including the numerous potential interactions between independently developed elements of the system. The term “interstitials” is used to define the domain of interfaces, interoperability, and integration between constituent systems in an SoS. The authors feel that this domain, at an SoS level, has received insufficient attention within systems engineering literature. The BMDS represents a challenging SoS case study as many of its initial elements were assembled from existing programs of record. The elements tend to perform as designed but their performance measures may not be consistent with the higher level SoS requirements. One of the BMDS challenges is interoperability, to focus the independent elements to interact in a number of ways, either subtle or overt, for a predictable and sustainable national capability. New capabilities desired by national leadership may involve modifications to kill chains, Command and Control (C2) constructs, improved coordination, and performance. These capabilities must be realized through modifications to programs of record and integration across elements of the system that have their own independent programmatic momentum. A challenge of SoS Engineering is to objectively evaluate competing solutions and assess the technical viability of tradeoff options. This paper will present a multifaceted technical approach for integrating a complex, adaptive SoS to achieve a functional capability. Architectural frameworks will be explored, a mathematical technique utilizing graph theory will be introduced, adjuncts to more traditional modeling and simulation techniques such as agent based modeling will be explored, and, finally, newly developed technical and managerial metrics to describe design maturity will be introduced. A theater BMDS construct will be used as a representative set of elements together with the interstitials representing the integration domain. Increased attention to the interstitial space of the overarching BMDS SoS construct and applying appropriate technical rigor and engineering due diligence with these added tools should greatly assist the BMDS in realizing its potential. © 2010 Wiley Periodicals, Inc. Syst Eng 14: 87–109, 2011

High Temperature Superconducting Degaussing From Feasibility Study to Fleet Adoption

Abstract: The need for increased magnetic signature control on Navy ships has lead to the development and adoption of a three axis advanced degaussing system. While this system is effective in reducing the ship magnetic signature, it requires significantly more copper cable than the legacy two axis systems. Degaussing only requires DC currents for field manipulation. Since DC applications is where HTS use excels, a feasibility study was conducted in FY04 to determine the benefits of HTS when used in an advanced degaussing system. Results showed reduced system size and weight, while remaining cost neutral. A series of lab based demonstrations were conducted proving out key aspects of an HTS DG system, most notably cooling a long length of flexible cryostat with gaseous helium. This led to an at sea demonstration of a single HTS DG loop aboard the USS Higgins. This was the first HTS system installed on an active combatant, and it made a successful magnetic range run in April 2009 demonstrating its capability to perform in a naval environment. This paper details the development of the HTS DG system from the initial feasibility study through the successful demonstration onboard the USS HIGGINS.

Probabilistic Analysis of Roll Parametric Resonance in Head Seas

Abstract: The paper presents some background for an analysis of the risk of severe parametric roll motion for a ship operating in head seas This background includes a consideration of basic probabilistic qualities of parametric roll in head seas: ergodic qualities and distributions, since these results are necessary to establish a method of prediction of extreme values The ship motions that generate parametric excitation, heave and pitch, have also been studied in this analysis The post- Panamax C11 class container carrier was chosen for analysis, since a vessel of this type is known to have suffered significant damage in an incident attributed to severe parametric roll It was shown that despite large-amplitude of motion, pitch and heave retain their ergodic qualities and normal character of distribution, while the roll motions are clearly non-ergodic and do not have a normal distribution The analysis is built upon the numerical simulation of ship motion in head seas using Large Amplitude Motion Program (LAMP)

A Comprehensive Sub-Grid Air Entrainment Model for RaNS Modeling of Free-Surface Bubbly Flows

Abstract: The simulation of free surface bubbly flows using a two-fluid model remains a challenging problem in part due to the lack of a comprehensive air entrainment model that can predict the rate and location of air entrainment for a wide range of flows. In this study we derive a sub-grid model and implement it in a computational multiphase fluid dynamics (CMFD) framework to solve the Reynolds-averaged two-fluid equations. We assess the performance of our model in simulating bubbly flows underneath a plunging liquid jet and a hydraulic jump while varying the characteristic velocity. We compare the void fraction predictions with their experimental counterparts and conclude that the air entrainment model and the two-fluid modeling approach yield accurate results everywhere for the plunging jet and in the turbulent shear layer for the hydraulic jump. The inability of the proposed approach to recover the high void fraction in the roller region of the hydraulic jump is attributed to the failure of RaNS model to resol...

Achieving reusability and composability with a simulation conceptual model

Abstract: Reusability and composability (R&C) are two important quality characteristics that have been very difficult to achieve in the Modelling and Simulation (M&S) discipline. Reuse provides many technical and economical benefits. Composability has been increasingly crucial for M&S of a system of systems, in which disparate systems are composed with each other. The purpose of this paper is to describe how R&C can be achieved by using a simulation conceptual model (CM) in a community of interest (COI). We address R&C in a multifaceted manner covering many M&S areas (types). M&S is commonly employed where R&C are very much needed by many COIs. We present how a CM developed for a COI can assist in R&C for the design of any type of large-scale complex M&S application in that COI. A CM becomes an asset for a COI and offers significant economic benefits through its broader applicability and more effective utilization.

Noncovalent interactions in paired DNA nucleobases investigated by terahertz spectroscopy and solid-state density functional theory.

Abstract: Cocrystallized adenine and thymine derivatives, along with the pure monomeric crystals, were investigated by terahertz spectroscopy and solid-state density functional theory (DFT). The methylated nucleobase derivatives crystallize in planar hydrogen-bonded adenine-thymine pairs similar to the manner found in DNA. The spectra obtained for 1-methylthymine, 9-methyladenine, and the 1:1 cocrystal in the range of 10−100 cm−1 clearly demonstrate that absorptions in this spectral range originate from the uniquely ordered assembly and the intermolecular interactions found in each individual crystal system. The quality of spectral reproduction for the DFT simulations of each system was clearly improved by the inclusion of an empirical correction term for London-type dispersion forces to the calculations. Notably, it was found that these weak dispersion forces in the adenine-thymine cocrystal were necessary to produce a properly converged crystal structure and meaningful simulation of the terahertz vibrational spec...

Bacillus anthracis interacts with plasmin(ogen) to evade C3b-dependent innate immunity.

Abstract: The causative agent of anthrax, Bacillus anthracis, is capable of circumventing the humoral and innate immune defense of the host and modulating the blood chemistry in circulation to initiate a productive infection. It has been shown that the pathogen employs a number of strategies against immune cells using secreted pathogenic factors such as toxins. However, interference of B. anthracis with the innate immune system through specific interaction of the spore surface with host proteins such as the complement system has heretofore attracted little attention. In order to assess the mechanisms by which B. anthracis evades the defense system, we employed a proteomic analysis to identify human serum proteins interacting with B. anthracis spores, and found that plasminogen (PLG) is a major surface-bound protein. PLG efficiently bound to spores in a lysine- and exosporium-dependent manner. We identified α-enolase and elongation factor tu as PLG receptors. PLG-bound spores were capable of exhibiting anti-opsonic properties by cleaving C3b molecules in vitro and in rabbit bronchoalveolar lavage fluid, resulting in a decrease in macrophage phagocytosis. Our findings represent a step forward in understanding the mechanisms involved in the evasion of innate immunity by B. anthracis through recruitment of PLG resulting in the enhancement of anti-complement and anti-opsonization properties of the pathogen.

Combustion of alane and aluminum with water for hydrogen and thermal energy generation

Abstract: The combustion of alane and aluminum with water in its frozen state has been studied experimentally and theoretically. Both nano and micron-sized particles are considered over a broad range of pressure. The linear burning rate and chemical efficiency are obtained using a constant-pressure strand burner and constant-volume cell, respectively. The effect of replacing nano-Al particles by micron-sized Al and alane particles are examined systematically with the additive mass fraction up to 25%. The equivalence ratio is fixed at 0.943. The pressure dependence of the burning rate follows the power law, r b = aP n , with n ranging from 0.41 to 0.51 for all the materials considered. The burning rate decreases with increasing alane concentration, whereas it remains approximately constant with cases containing only Al particles. The chemical efficiency ranged from 32% to 83%, depending on the mixture composition and pressure. Thermo-chemical analyses are conducted to provide insight into underlying causes of the decreased burning rate of the alanized compositions. A theoretical model is also developed to explore the detailed flame structure and burning properties. Reasonably good agreement is achieved with experimental observations.

Structure, morphology and magnetic properties of Mg((x))Zn((1 - x))Fe2O4 ferrites prepared by polyol and aqueous co-precipitation methods: a low-toxicity alternative to Ni((x))Zn((1 - x))Fe2O4 ferrites.

Abstract: The synthesis and properties of Mg((x))Zn((1 - x))Fe(2)O(4) spinel ferrites as a low-toxicity alternative to the technologically significant Ni((x))Zn((1 - x))Fe(2)O(4) ferrites are reported. Ferrite nanoparticles have been formed through both the polyol and aqueous co-precipitation methods that can be readily adapted to industrial scale synthesis to satisfy the demand of a variety of commercial applications. The structure, morphology and magnetic properties of Mg((x))Zn((1 - x))Fe(2)O(4) were studied as a function of composition and particle size. Scanning electron microscopy images show particles synthesised by the aqueous co-precipitation method possess a broad size distribution (i.e. ∼ 80-120 nm) with an average diameter of the order of 100 nm ± 20 nm and could be produced in high process yields of up to 25 g l(-1). In contrast, particles synthesised by the polyol-based co-precipitation method possess a narrower size distribution with an average diameter in the 30 nm ± 5 nm range but are limited to smaller yields of ∼ 6 g l(-1). Furthermore, the polyol synthesis method was shown to control average particle size by varying the length of the glycol surfactant chain. Particles prepared by both methods are compared with respect to their phase purity, crystal structure, morphology, magnetic properties and microwave properties.

KDNP – A Lead Free Replacement for Lead Styphnate

Abstract: Efforts directed towards creating new environmentally friendly replacements for existing primary explosives have resulted in development of potassium 5,7-dinitro-[2,1,3]-benzoxadiazol-4-olate 3-oxide (KDNP). The chemical and physical properties of this material have been investigated and it appears that KDNP is a suitable drop-in replacement for lead styphnate in a variety of ordnance applications. KDNP is easily prepared, has excellent thermal stability and has safety and performance properties, which are equivalent to or exceed those for lead styphnate. KDNP has been qualified for military use per NAVSEAINST 8020.5C.

Explorations of Hybrid Sandwich Panel Concepts for Projectile Impact Mitigation

Abstract: Previous studies have shown that while stainless-steel sandwich panels with pyramidal truss cores have a superior blast resistance to monolithic plates of equal mass per unit area, their ballistic performance is similar to their monolithic counterparts. Here, we explore concepts to enhance the ballistic resistance without changing the volumetric efficiency of the panels by filling the spaces within the core with combinations of polyurethane, alumina prisms, and aramid fiber textiles. The addition of the polyurethane does not enhance the ballistic limit compared with the equivalent monolithic steel plate, even when aramids are added. This poor performance occurs because the polymer is penetrated by a hole enlargement mechanism which does not result in significant projectile deformation or load spreading and engagement of the steel face sheets. By contrast, ceramic inserts deform and erode the projectile and also comminute the ceramic. The ceramic communition (and resultant dilation) results in stretching of both steel face sheets and leads to significant energy dissipation. The ballistic limit of this hybrid is about twice that of the equivalent monolithic steel plate. The addition of a Kevlar fabric to the ceramic hybrid is shown to not significantly change the ballistic limit but does reduce the residual velocities of the debris.

Reverberant Microwave Propagation in Coupled Complex Cavities

Abstract: A simple model for the analysis of microwave propagation in coupled complex cavities is presented. The cumulative build-up and full exchange of electromagnetic energy between coupled spaces are important issues for wireless systems in reverberant environments, such as below-deck compartments in ships and aircraft cabins and bays. Based on conservation of average energy in the steady state among multiple cavities, the general model formulation is valid for both strong and weak couplings between the cavities caused by window materials, open apertures, closed and open hatches, and cable/pipe penetrations through bulkheads. Application of the model is demonstrated in conjunction with measurements conducted in nested reverberation chambers in the laboratory and in the coupled main weapons bays of a fighter aircraft.

Silicone Polymer Composites for Thermal Protection System: Fiber Reinforcements and Microstructures

Abstract: A new class of silicone polymer matrix composites was evaluated using a simulated solid rocket motor test apparatus. Conversion of this organic silicone polymer to a ceramic (i.e. silica) structure on exposure to flame impingement or high temperature, accounts for its outstanding thermal stability. A research program was aimed to develop and evaluate this new class of thermal protection materials for military applications. This article presents the effects of the type and form of reinforcements on the thermal performance of a novel class of silicone polymer matrix composites. Reinforcement types such as glass, silica, quartz, NextelTM, and NicalonTM were used. Reinforcement forms such as random continuous-fiber mat, chopped-fiber mat, 2-D fabric, 3-D fabric, chopped roving, and broadgood tapes with different ply angles were tested. Detailed microstructural, mass loss, and peak erosion analyses were conducted on the phenolic-based matrix composite (control) and silicone-based matrix composites to understan...

Review of Available Methods for Application to Second Level Vulnerability Criteria

Abstract: The International Maritime Organization (IMO) has begun work on the development of next generation intact stability criteria. These criteria are likely to consist of several levels: from simple to complex. The first levels are expected to contain vulnerability criteria and are generally intended to identify if a vessel is vulnerable to a particular mode of stability failure. These vulnerability criteria may consist of relatively simple formulations, which are expected to be quite conservative to compensate for their simplicity. This paper reviews methods which may be applicable to the second level of vulnerability assessment, when simple but physics-based approaches are used to assess the modes of stability failure, including pure-loss of stability, parametric roll, surf-riding, and dead-ship condition.

Underwater Explosion Phenomena and Shock Physics

Abstract: This paper presents a brief introduction to the basic fundamentals of underwater explosions, including discussion of the features of explosive charge detonation, the formation and characterization of the associated shock wave, bulk cavitation effects, gas bubble formation and dynamics, surface effects and shock wave refraction characteristics. Illustrations of each of these fundamental aspects of underwater explosion (UNDEX) loadings are made with a set of videos from a variety of experimental testing events. In addition, analyses of associated measured loading and dynamic response data, as well as descriptions of supporting numerical simulations of these events are presented. At the conclusion of this paper, each of these UNDEX effects are tied together with a summary discussion and illustration.

Numerical Procedures and Practical Experience of Assessment of Parametric Roll of Container Carriers

Abstract: The paper examines several aspects related to practical assessment of parametric roll of container carriers. The numerical procedure is based on application of the Large Amplitude Motion Program (LAMP), the nonlinear potential flow code. Viscous roll damping is included from the roll decay test. The rational choice of the loading conditions is considered. Practical non-ergodicity of the response is taken into account.

Multi-antenna near field cancellation duplexing for concurrent transmit and receive

Abstract: Concurrent transmit and receive with multiple antennas is demonstrated through near field cancellation. Full-duplex operation is possible through cancellation of the transmit signal at the receiver as much as 50dB. By exploiting symmetry in an array of antennas, a centrally located receiver is able to operate without saturation in the presence of high power transmit signals. The transmitters are able to provide spatial diversity and 360-degree azimuthal coverage while maintaining the requisite cancellation. We demonstrate the basic concept and then explore the criteria within the RF components needed to maintain suitable cancellation.

Decontamination of a hard surface contaminated with Bacillus anthracisΔSterne and B. anthracis Ames spores using electrochemically generated liquid-phase chlorine dioxide (eClO2).

Abstract: Aims: To evaluate the inactivation of Bacillus anthracisΔSterne and Ames spores using electrochemically generated liquid-phase chlorine dioxide (eClO2) and compare two sporulation and decontamination methods with regard to cost, safety and technical constraints. Methods and Results: Spores were prepared via agar and broth methods and subsequently inoculated and dried onto clean, autoclave-sterilized glass coupons. Bacillus anthracis spore inactivation efficacy was evaluated using the modified three-step method (AOAC 2008.05) and a single-tube extraction method. Spores (7·0 ± 0·5 logs) were inactivated within 1 min at room temperature using freshly prepared eClO2. Bacillus anthracisΔSterne spores decreased in size after eClO2 treatment as measured using a Beckman Coulter Multisizer. Conclusions: eClO2 saturation of a hard surface was an effective B. anthracis sporicide. Broth sporulation and the single-tube extraction method required less time and fewer steps, yielded a higher percentage of phase-bright spores and showed higher spore recovery efficiency compared with AOAC 2008.05, making it more amenable to biosafety level 3 (BSL3) testing of virulent spores. Significance and Impact of the Study: Two test methods demonstrated the sporicidal efficacy of eClO2. A new single-tube extraction test protocol for decontaminants was introduced.

Water temperature and concentration measurements within the expanding blast wave of a high explosive

Abstract: We present an application of absorption spectroscopy to directly measure temperature and concentration histories of water vapor within the expansion of a high explosive detonation. While the approach of absorption spectroscopy is well established, the combination of a fast, near-infrared array, broadband light source, and rigid gauge allow the first application of time-resolved absorption measurements in an explosive environment. The instrument is demonstrated using pentaerythritol tetranitrate with a sampling rate of 20 kHz for 20 ms following detonation. Absorption by water vapor is measured between 1335 and 1380 nm. Water temperatures are determined by fitting experimental transmission spectra to a simulated database. Water mole fractions are deduced following the temperature assignment. The sources of uncertainty and their impact on the results are discussed. These measurements will aid the development of chemical-specific reaction models and the predictive capability in technical fields including combustion and detonation science.