Performance evaluation of the AN USQ / 146 Jammer over uncoded slow FH/MFSK military communication systems and the IEEE 802.1 1a wireless LAN commecial communication standard

On the modern battlefield communication is critical. Individual units require a steady flow of accurate information between headquarters and field units to remain effective. Just as important, denying the enemy the same needs of communicating with the help of electronic countermeasures (ECM), is essential to success. Communications jamming and surveillance are critical to achieve information superiority. This thesis evaluates the performance and capabilities of one of the most advanced devices that detects, analyzes and denies enemy signals: the Rockwell Colins AN/USQ - 146 transportable communication jammer. The jammer’s best strategy varies with respect to the modulation technique that the hostile communication system uses. As the theoretical analysis and the simulation results indicated, the AN/USQ -146 jammer achieves its best performance over a FH/MFSK system when it selects the repeat multitone jamming strategy. However, when the hostile communication system is the IEEE 802.11a wireless local area network (WLAN) system, the AN/USQ - 146 (Rubicon II) jammer must select the partial-band jamming strategy with ρ = 0.1. The results of the theoretical analysis and the simulation modeling of the specific jammer for all types of jamming in manual spot and repeat modes over FH/MFSK military communication systems and new advanced wireless standards such as the IEEE 802.11a can be used as guidelines to select the most effective jamming strategy for the specific type of hostile waveform encountered.http://archive.org/details/performanceevalu1094544697Lieutenant, Hellenic NavyApproved for public release; distribution is unlimited

"SEA ARCHER" Distributed Aviation Platform

Includes supplementary material.This report outlines the results of a two quarter Total Ship Systems Engineering (TSSE) Capstone design project undertaken by the students at the Naval Postgraduate School. The project was under the direction of Professors C.N. Calvano and R.Harney.Currently, no system exists that provides a sea-based distributed aviation platform capability. The emergence of Unmanned Air Vehicles (UAVs) / Unmanned Combat Air Vehicles (UCAVs), the continued U.S. Navy focus on the littorals, the desire for force distribution, the need for operational cost reductions, and the advent of Network Centric Warfare (NCW) all continue to support the requirement to re-evaluate how littoral operations will be conducted in the future. Given this background, a bottom-up design of a ship supporting a primarily UAV/UCAV air wing in a low to medium threat environment is of significant interest. SEA ARCHER meets this interest. This report outlines a design that meets the future needs for distributed aviation with a high-speed, highly automated platform. Large gains in reduced manning through automated systems for both operation and damage control helpmeet the demanding needs for the future of the Navy at reduced operational costs. The report will outline both the Mission Needs Statement (MNS) and Operational Requirements Document (ORD) for the ship that was developed. The analysis of alternatives that was conducted to determine relative size requirements for the ship in presented in the next section. The concept design that resulted as a result of the Total Ship Systems Engineeing process in then presented. Finally, a detailed look at the analysis and trade studies that were conducted in presented in order to show the more detailed analysis that was conducted in designing the ship.http://archive.org/details/seaarcherdistrib109457277US Navy (USN) authorsHellenic Navy authorTurkish Navy authorsSingapore Defense Science and Technology Agency author (civilian)Approved for public release; distribution is unlimited

A coupled hydrodynamic/structural model for ship/ramp/barge interface

A mathematical model describing the fundamental dynamics in the interface problem between a ship, a barge, and a connecting ramp is developed and solved. The hydrodynamics for the ship and the barge are described by a 12-degree of freedom fully coupled model, which is based on potential theory and incorporates proximity effects. Ramp structural dynamics are studied by a finite element model, which has been calibrated based on detailed studies of commercially available codes. The models were coupled together through a spring/damper and the solution of the system was obtained in both regular waves and a representative sea state. Parametric studies with regards to different coupling conditions indicate that optimization based on either relative motions or ramp maximum stress is possible.http://archive.org/details/acoupledhydrodyn109451320Hellenic Navy autho

4. TITLE AND SUBTITLE: A Coupled Hydrodynamic/Structural Model for Ship/Ramp/Barge Interface

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Enhanced Surface Diffusion in Low-temperature a-Si:H Processing

ABSTRACTGlow discharge amorphous hydrogenated silicon (a-Si:H) prepared at near room temperature typically results in an inhomogeneous morphology that is undesirable for a number of thin film applications. The most commonly observed features of this include columnar morphology and surface roughness. This usually results from anodic deposition, where substrates are placed on the grounded electrode. We have discovered that placing substrates on the RF-powered electrode (referred to as cathodic deposition) offers a much wider processing range for homogenous growth than anodic growth. We have also found that the magnitude of the surface roughness and the bulk void fraction of both anodic and cathodic a-Si:H thin films processed at low-temperatures is proportional to ∼D/F, where D is the surface diffusivity and F, the adatom flux, though anodic and cathodic deposition affect these global parameters differently. Surface processes unique to cathodic deposition can enhance adatom surface diffusion, while diffusion during anodic deposition is fixed and cannot attain homogeneous growth at high adatom fluxes. Processing a-Si:H on the cathode, associated with enhanced adatom surface diffusion, allows for homogeneous growth even at high deposition rates that has benefits for a number of applications.</jats:p

Surface Roughness Evolution of PECVD Cathodic and Anodic <i>a</i>-Si:H.

AbstractSurface or interface roughness can impact optical, electronic, and MEMS applications of thin a-Si:H films. Deposition at lower temperatures can be advantageous for some applications of a-Si:H, but lower temperature deposition generally leads to rougher films. We have found that the evolution of surface roughness growth can be modified substantially by ion bombardment due to the self-bias of the plasma during Plasma-Enhanced Chemical Vapor Deposition (PECVD). Notable differences in the surface roughness evolution and deposition rate are shown for films deposited in “cathodic” versus “anodic” mode – where the substrate is placed on the powered and grounded electrode respectively. Suppression of surface roughness growth of a-Si:H can be achieved under conditions of relatively high ion bombardment even at deposition temperatures as low as 75 C. Atomic force microscopy (AFM) was used to measure the relative surface roughness profile as a function of deposition time. Analysis of the power spectral density of the roughness yielded important statistical surface parameter information. Based on these observations, insight is given into growth mechanisms under the two deposition conditions.</jats:p

Surface Roughness Study of Low-temperature PECVD <i>a</i>-Si:H.

AbstractSurface topography of a-Si:H thin films, deposited at 75°C by Plasma-enhanced Chemical Vapor Deposition (PECVD) has been examined using helium/silane feedstock mixtures under different substrate bias conditions. Notable differences in the surface roughness evolution are shown for films deposited in “cathodic” versus “anodic” mode – where the substrate is placed on the powered and grounded electrode respectively. Smooth and apparently featureless surfaces result from deposition on RF powered surfaces, upon which a self-bias induces high-energy ion bombardment. Rougher surfaces result from films deposited on electrically grounded surfaces. These anodic films show that after a transition period, surface roughness grows linearly with processing time, exhibiting mounded type growth as evidenced by 2-D power spectral density functions of surface height measurements. Linear growth in roughness has been predicted for shadow growth models assuming film precursor sticking coefficients of one and random angle approach of film precursor species. Growth of this nature has not been reported before in a-Si:H studies, which usually assume directional deposition conditions and sticking coefficients less than unity – occurring even at low processing temperatures.</jats:p