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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
Integrated Approach To Free Space Optical Communications In Strong Turbulence, Jason A. Tellez
Integrated Approach To Free Space Optical Communications In Strong Turbulence, Jason A. Tellez
Theses and Dissertations
The propagation of a free space optical communication signal through atmospheric turbulence experiences random fluctuations in intensity, including signal fades which negatively impact the communications link performance. This research develops an analytical probability density function (PDF) to model the best case scenario of using multiple independent beams to reduce the intensity fluctuations. The PDF was further developed to account for partially correlated beams, such as would be experienced by beams having finite separation. The PDF was validated with results obtained from digital simulations as well as lab experiments. The research showed that as the number of transmitted beams increases the …
Hyperspectral-Based Adaptive Matched Filter Detector Error As A Function Of Atmospheric Profile Estimation, Allan W. Yarbrough
Hyperspectral-Based Adaptive Matched Filter Detector Error As A Function Of Atmospheric Profile Estimation, Allan W. Yarbrough
Theses and Dissertations
Hyperspectral imagery is collected as radiance data. This data is a function of multiple variables: the radiation profile of the light source, the reflectance of the target, and the absorption and scattering profile of the medium through which the radiation travels as it reflects off the target and reaches the imager. Accurate target detection requires that the collected image matches as closely as possible the known "true" target in the classification database. Therefore, the effect of the radiation source and the atmosphere must be removed before detection is attempted. While the spectrum of solar light is relatively stable, the effect …
Oxygen Vacancies Adjacent To Cu(2+) Ions In Tio(2) (Rutile) Crystals, A. T. Brant, Shan Yang (杨山), Nancy C. Giles, Zafar Iqbal, A. Manivannan, Larry E. Halliburton
Oxygen Vacancies Adjacent To Cu(2+) Ions In Tio(2) (Rutile) Crystals, A. T. Brant, Shan Yang (杨山), Nancy C. Giles, Zafar Iqbal, A. Manivannan, Larry E. Halliburton
Faculty Publications
Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are used to characterize Cu2+ ions substituting for Ti4+ ions in nominally undoped TiO2 crystals having the rutile structure. Illumination at 25 K with 442 nm laser light reduces the concentration of Cu2+ ions by more than a factor of 2. The laser light also reduces the EPR signals from Fe3+ and Cr3+ ions and introduces signals from Ti3+ ions. Warming in the dark to room temperature restores the crystal to its preilluminated state. Monitoring the recovery of the photoinduced changes in the Cu …
Optical Metamaterial Design, Fabrication And Test, Jack P. Lombardi
Optical Metamaterial Design, Fabrication And Test, Jack P. Lombardi
Theses and Dissertations
Metamaterials, materials that make use of naturally occurring materials and designed structures to create materials with special properties not found in nature, are a fascinating new area of research, combining the fields of physics, microfabrication, and material science. This work will focus on the development of metamaterials operating in the visible and infrared which will be constructed and tested for basic optical properties. Possible applications for these materials will not be investigated. The this work will go into the fabrication and test of layered metal-dielectric structures, called layered metamaterials, as these structures hold potential for applications in advanced optical systems. …
Malicious And Malfunctioning Node Detection Via Observed Physical Layer Data, Tyler J. Hardy
Malicious And Malfunctioning Node Detection Via Observed Physical Layer Data, Tyler J. Hardy
Theses and Dissertations
There are many mechanisms that can cause inadequate or unreliable information in sensor networks. A user of the network might be interested in detecting and classifying specific sensors nodes causing these problems. Several network layer based trust methods have been developed in previous research to assess these issues; in contrast this work develops a trust protocol based on observations of physical layer data collected by the sensors. Observations of physical layer data are used for decisions and calculations, and are based on just the measurements collected by the sensors. Although this information is packaged and distributed on the network layer, …
Software And Critical Technology Protection Against Side Channel Analysis Through Dynamic Hardware Obfuscation, John R. Bochert
Software And Critical Technology Protection Against Side Channel Analysis Through Dynamic Hardware Obfuscation, John R. Bochert
Theses and Dissertations
Side Channel Analysis (SCA) is a method by which an adversary can gather information about a processor by examining the activity being done on a microchip though the environment surrounding the chip. Side Channel Analysis attacks use SCA to attack a microcontroller when it is processing cryptographic code, and can allow an attacker to gain secret information, like a crypto-algorithm's key. The purpose of this thesis is to test proposed dynamic hardware methods to increase the hardware security of a microprocessor such that the software code being run on the microprocessor can be made more secure without having to change …
Evaluating Information Assurance Control Effectiveness On An Air Force Supervisory Control And Data Acquisition (Scada) System, Jason R. Nielsen
Evaluating Information Assurance Control Effectiveness On An Air Force Supervisory Control And Data Acquisition (Scada) System, Jason R. Nielsen
Theses and Dissertations
Supervisory Control and Data Acquisition (SCADA) systems are increasingly being connected to corporate networks which has dramatically expanded their attack surface to remote cyber attack. Adversaries are targeting these systems with increasing frequency and sophistication. This thesis seeks to answer the research question addressing which Information Assurance (IA) controls are most significant for network defenders and SCADA system managers/operators to focus on in order to increase the security of critical infrastructure systems against a Stuxnet-like cyber attack. This research applies the National Institute of Science and Technology (NIST) IA controls to an attack tree modeled on a remote Stuxnet-like cyber …