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Investigating Turbulence Distribution in the Lower Atmosphere using Time-lapse Imagery from a Camera Bank
Get PDFThe atmosphere’s surface layer (first 50–100 m above the ground) is extremely dynamic and is influenced by surface radiative properties, roughness, and atmospheric stability. Understanding the distribution of turbulence in the surface layer is critical to many applications, such as directed energy and free space optical communications. Several measurement campaigns in the past have relied on weather balloons or sonic detection and ranging (SODAR) to measure turbulence up to the atmospheric boundary layer. However, these campaigns had limited measurements near the surface. We have developed a time-lapse imaging technique to profile atmospheric turbulence from turbulence-induced differential motion or tilts between features on a distant target, sensed between pairs of cameras in a camera bank. This is a low-cost and portable approach to remotely sense turbulence from a single site without the deployment of sensors at the target location. It is thus an excellent approach to study the distribution of turbulence in low altitudes with sufficiently high resolution. In the present work, the potential of this technique was demonstrated. We tested the method over a path with constant turbulence. We explored the turbulence distribution with height in the first 20 m above the ground by imaging a 30 m water tower over a flat terrain on three clear days in summer. In addition, we analyzed time-lapse data from a second water tower over a sloped terrain. In most of the turbulence profiles extracted from these images, the drop in turbulence with altitude in the first 15 m or so above the ground showed a hm dependence, where the exponent m varied from -0.3 to -1.0, quite contrary to the widely used value of -4/3. Abstract © Optica
Trapped Ion Quantum Computing: A Framework for Addressing Security Vulnerabilities
No full textTrapped ion quantum computing has the potential to revolutionize computational paradigms. As the adoption of this technology grows, so does the need for stringent scrutiny of its involvement in cybersecurity, especially when it has implications in national defense or critical infrastructure. While trapped ion quantum computing offers transformative capabilities, it is vital to carefully examine the potential vulnerabilities associated with its use and patch them before implementing this powerful technology. In this paper, we examine the potential vulnerabilities in trapped ion quantum computing systems and propose a framework for addressing them. This framework includes risk assessment for evaluating vulnerabilities, threat modeling for identifying exploits, and prevention and mitigation for reducing their impact
Dual-Channel Side Channel Attack: Improved AES Key Decryption by Combining Power and Electromagnetic Side Channels with Convolutional Neural Networks
No full textThis research introduces a novel DL approach for SCA that combines power consumption and EM signals to enhance encryption key deduction by leveraging a dual-channel CNN architecture. A new dataset, consisting of simultaneous power and EM signal collections during 128-bitAES encryption, was developed to train and evaluate the model’s effectiveness. The combined approach achieved an 88% reduction in traces needed, from 50 traces to 6, for encryption key classification, outperforming traditional methods such as random forest, DPA, DEMA,and individual side channel CNN models. These findings highlight the potential of integrating multiple side channels in SCA to improve performance without the need for tedious feature extraction techniques
Grit and the Military Service Member: How Cultivating Grit Enhances Performance, Resilience, and Mental Health
No full textThe transition from asymmetric warfare to Great Power Competition has brought the role played by Airmen to the forefront of the conversation. When uncontested operations, superior weaponry, and more detailed intelligence are not guaranteed, the weight of victory rests on the shoulders of Airmen. The exploration of grit and the role it plays in the development and sustainment of mental wellness, resilience, and performance has emerged in this context as a linchpin quality. The idea that an inherent drive, determination, and strength of purpose could offset the impact of stress—both combat and noncombat—is deeply compelling. However, leaders cannot look to grit as a quick solution to a complex problem without an investigation of the ethical challenges this holds. Can grit be developed? Is there a way to increase grit ethically, without risking further harm? How do we address the societal and systemic challenges that have made grit a requirement? How do we laud grit while not absolving ourselves, as leaders, of the responsibility to build stronger, safer operating environments for our Airmen, preserving their grit and tenacity for use on the battlefield? The issues are complex, and this paper offers an insightful window into their nuances. Proceed with humility, curiosity, and an openness to learn
Gated Reflect Line Self-Calibration Technique for Accurate Material Parameter Extraction with Focus Beam Systems
No full textThis paper introduces a self-calibration Gated Reflect Line technique of free-space focus beam systems with experimental results for validation. The procedure assumes same surface of the Reflect standard is used to measure the back scattered channels of each network analyzer port. Equivalent cascaded scattering parameter blocks are then formulated to identify the reflection coefficient of the Reflect metrology standard. The calibration scheme is subsequently updated to include the actual reflection coefficient rather than use the ideal metal plate assumption. Finally, measured results with a 2–18 GHz focus beam system and plexiglass sample are included to compare the self-calibration to conventional technique with a Monte Carlo error analysis. This self-calibration procedure accounts for imperfections in the Reflect standard where any deviations from an ideal perfect electrical conductor result in residual errors. The introduced technique enhances the measurement accuracy and enables loss tangent extraction of low-loss materials
Development of the Ionospheric E‐Region Prompt Radio Occultation Based Electron Density (E‐PROBED) Model
No full textThis work reports the development of the first version of the E-region Prompt Radio Occultation Based Electron Density (E-PROBED) Model. This is an empirical model of E-region electron density (Ne) between 90 and 120 km developed using radio occultation measurements from the COSMIC-1 mission. This first version captures more than 80% of the observed variability in monthly-mean latitude-local time-altitude E-region Ne profiles but it does not account for longitudinal variability at constant local-time. This work also reports a validation of E-PROBED simulations through comparisons with ionosondes and incoherent scatter radar (ISR) E-region Ne profiles. E-PROBED generally agrees with these ground-based observations during day-time. During night-time, there is a large disparity between E-PROBED and ISR values. Finally, this work compares E-PROBED with E-region Ne simulated by the International Reference Ionosphere (IRI) and the Specified Dynamics—Whole Atmosphere Community Climate Model with Ionosphere/Thermosphere eXtension (SD-WACCM-X). One of the main differences amongst these models is on the simulation of variabilities that cannot be attributed to photoionization. IRI barely simulates any variability not driven by photoionization. Both E-PROBED and SD-WACCM-X simulates variability not driven by photoionization. Another main difference is in the absolute magnitude of night-time E-region Ne values. Both IRI and SD-WACCM-X are substantially lower than E-PROBED. This work first concludes that E-PROBED can conveniently provide E-region Ne latitude—local time variabilities and structures that COSMIC-1 observes. This work also concludes that E-region Ne have significant non-photoionization driven variabilities
Limitations of Beam-control Compensation
Get PDFIn this paper, we use wave-optics simulations to explore the limitations of beam-control compensation. We evaluate performance in terms of the normalized power in a diffraction-limited bucket for the cases of no beam-control compensation, perfect phase compensation, and perfect full-field compensation. From these results, we are able to arrive at the following conclusions: (1) without any form of beam-control compensation, performance begins to degrade when D/r0 \u3e 1; (2) with perfect phase compensation, performance begins to degrade when D/r0 \u3e 1 and (λ/r0)/θ0 \u3e 1; and (3) with perfect full-field compensation, performance begins to degrade when D/r0 \u3e 1 and (λ/D)/θ0 \u3e 1. Here, D is the aperture diameter, r0 is the Fried parameter, λ is the wavelength, and θ0 is the isoplanatic angle. We show (1)–(3) to be true for varying aperture diameters, uniformly distributed turbulence, and varying turbulence profiles. These findings will inform the development of future laser systems that need to sense and correct for the effects of atmospheric turbulence
