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Articles 1 - 11 of 11
Full-Text Articles in Physical Sciences and Mathematics
Bayesian Estimation Of Asymmetric Jump-Diffusion Processes, Samuel J. Frame, Cyrus A. Ramezani
Bayesian Estimation Of Asymmetric Jump-Diffusion Processes, Samuel J. Frame, Cyrus A. Ramezani
Statistics
The hypothesis that asset returns are normally distributed has been widely rejected. The literature has shown that empirical a<>set returns are highly skewed and Ieptokurtic. The affine jump-diffusion (AJD) model improves upon the normal specification by adding a jump component to the price process. Two important extensions proposed by Ramezani and Zeng (1998) and Kou (2002) further improve the AJD specification by having two jump components in the price process, resulting in the asymmetric affine jump-diffusion (AAJD) specification. The AAJD specification allows the probability distribution of the returns to be asymmetrical. That is, the tails of the distribution are …
Boresight Alignment Station, Marco A. Scussat, Richard M. Goeden, Jeffrey S. Scott, Richard G. Lane, Gary B. Hughes
Boresight Alignment Station, Marco A. Scussat, Richard M. Goeden, Jeffrey S. Scott, Richard G. Lane, Gary B. Hughes
Statistics
A boresight alignment system facilitates aligning a plurality of cameras and/or images of the cameras with respect to one another. The system may have a mount configured to facilitate attachment of a bezel containing a plurality of cameras to the mount. The system may have a plurality of targets and each target may be configured to provide light of at least two different wavelengths and/or ranges of wavelengths. One or more baffles may be disposed optically between the mount and the target assembly to inhibit stray light from being incident upon the cameras.
Directed Energy Active Illumination For Near-Earth Object Detection, Jordan Riley, Philip Lubin, Gary B. Hughes, Hugh O'Neill, Peter Meinhold, Jonathan Suen, J Bible, Isabella E. Johansson, Janelle Griswold, Brianna Cook
Directed Energy Active Illumination For Near-Earth Object Detection, Jordan Riley, Philip Lubin, Gary B. Hughes, Hugh O'Neill, Peter Meinhold, Jonathan Suen, J Bible, Isabella E. Johansson, Janelle Griswold, Brianna Cook
Statistics
On 15 February 2013, a previously unknown ~20 m asteroid struck Earth near Chelyabinsk, Russia, releasing kinetic energy equivalent to ~570 kt TNT. Detecting objects like the Chelyabinsk impactor that are orbiting near Earth is a difficult task, in part because such objects spend much of their own orbits in the direction of the Sun when viewed from Earth. Efforts aimed at protecting Earth from future impacts will rely heavily on continued discovery. Ground-based optical observatory networks and Earth-orbiting spacecraft with infrared sensors have dramatically increased the pace of discovery. Still, less than 5% of near-Earth objects (NEOs) 100 m/~100 …
Optical Modeling For A Laser Phased-Array Directed Energy System, Gary B. Hughes, Philip Lubin, Janelle Griswold, Brianna Cook, Durante Bozzini, Hugh O'Neill, Peter Meinhold, Jonathan Suen, J Bible, Jordan Riley, Isabella E. Johansson, Mark Pryor, Miikka Kangas
Optical Modeling For A Laser Phased-Array Directed Energy System, Gary B. Hughes, Philip Lubin, Janelle Griswold, Brianna Cook, Durante Bozzini, Hugh O'Neill, Peter Meinhold, Jonathan Suen, J Bible, Jordan Riley, Isabella E. Johansson, Mark Pryor, Miikka Kangas
Statistics
We present results of optical simulations for a laser phased array directed energy system. The laser array consists of individual optical elements in a square or hexagonal array. In a multi-element array, the far-field beam pattern depends on both mechanical pointing stability and on phase relationships between individual elements. The simulation incorporates realistic pointing and phase errors. Pointing error components include systematic offsets to simulate manufacturing and assembly variations. Pointing also includes time-varying errors that simulate structural vibrations, informed from random vibration analysis of the mechanical design. Phase errors include systematic offsets, and time-varying errors due to both mechanical vibration …
De-Starlite: A Directed Energy Planetary Defense Mission, Kelly Kosmo, Mark Pryor, Philip Lubin, Gary B. Hughes, Hugh O'Neill, Peter Meinhold, Jonathan Suen, Jordan Riley, Janelle Griswold, Brianna Vail Cook, Isabella E. Johansson, Qicheng Zhang, Kevin Walsh, Carl Melis, Miikka Kangas, J Bible, Caio Motta, Travis Brashears, Shana Mathew, Justin Bollag
De-Starlite: A Directed Energy Planetary Defense Mission, Kelly Kosmo, Mark Pryor, Philip Lubin, Gary B. Hughes, Hugh O'Neill, Peter Meinhold, Jonathan Suen, Jordan Riley, Janelle Griswold, Brianna Vail Cook, Isabella E. Johansson, Qicheng Zhang, Kevin Walsh, Carl Melis, Miikka Kangas, J Bible, Caio Motta, Travis Brashears, Shana Mathew, Justin Bollag
Statistics
This paper presents the motivation behind and design of a directed energy planetary defense system that utilizes laser ablation of an asteroid to impart a deflecting force on the target. The proposed system is called DE-STARLITE for Directed Energy System for Targeting of Asteroids and ExploRation – LITE as it is a small, stand-on unit of a larger standoff DE-STAR system. Pursuant to the stand-on design, ion engines will propel the spacecraft from low-Earth orbit (LEO) to the near-Earth asteroid (NEA). During laser ablation, the asteroid itself becomes the "propellant"; thus a very modest spacecraft can deflect an asteroid much …
Using Remote Sensing Data To Predict The Spread Of Mosquito Borne Disease, Mary Ellen O'Donnell, Erika Podest
Using Remote Sensing Data To Predict The Spread Of Mosquito Borne Disease, Mary Ellen O'Donnell, Erika Podest
STAR Program Research Presentations
There is interest in how environmental variables derived from satellite data such as temperature, vegetation cover, and precipitation correlate to vector borne disease occurrence such as malaria and dengue fever. This study will be carried out using a decision tree based open source software called Random Forests to find correlations between the remote sensing variables and mosquito abundance. Software will be written in C# to take large amounts of data from the NASA satellite database and automatically format it for the Random Forest Software input. Correlations found, using Random Forests, between disease incidence and the variables can be used as …
The Path To The Sea: Leatherback Hatchling Orientation At Sandy Point National Wildlife Refuge, Christina Macmillan, Kelly Stewart
The Path To The Sea: Leatherback Hatchling Orientation At Sandy Point National Wildlife Refuge, Christina Macmillan, Kelly Stewart
STAR Program Research Presentations
Once sea turtle hatchlings emerge from their nest, they must find their way to the ocean by using cues such as a bright horizon and the slope of the beach. While moving toward the water, hatchlings often must navigate past predators and through vegetation, sticks, footprints in the sand, and other dangers such as ghost crab holes. Sometimes hatchlings become confused (or disoriented) and turn in circles to find the right route to the water. Sea turtle hatchlings also may become disoriented as a result of human impacts such as town lights or trash. The purpose of our experiment was …
Light Pollution Research Through Citizen Science, John Kanemoto
Light Pollution Research Through Citizen Science, John Kanemoto
STAR Program Research Presentations
Light pollution (LP) can disrupt and/or degrade the health of all living things, as well as, their environments. The goal of my research at the NOAO was to check the accuracy of the citizen science LP reporting systems entitled: Globe at Night (GaN), Dark Sky Meter (DSM), and Loss of the Night (LoN). On the GaN webpage, the darkness of the night sky (DotNS) is reported by selecting a magnitude chart. Each magnitude chart has a different density/number of stars around a specific constellation. The greater number of stars implies a darker night sky. Within the DSM iPhone application, a …
Tuffoam Density Variation Through Radiography, Sergio Contreras Esquivel
Tuffoam Density Variation Through Radiography, Sergio Contreras Esquivel
STAR Program Research Presentations
TufFoam is a low density, high impact tolerant polyurethane foam with good high voltage breakdown developed at the Sandia National Laboratories. Identically shaped samples have been produced with various formulations and production conditions. Eight different variables were studied. Our aim is to compare the density variation of the material when produced and processed under distinct conditions. The density of TufFoam is determined using radiographic imaging. We extract the foam density by fitting the radiographic density of each step in a plastic step wedge with 10 steps from 0.1 to 1.0 inches and applying the resulting equation to convert each pixel …
Toward Directed Energy Planetary Defense, Philip Lubin, Gary B. Hughes, J Bible, Jesse Bublitz, Josh Arriola, Caio Motta, Jon Suen, Isabella Johansson, Jordan Riley, Nilou Sarvian, Deborah Clayton-Warwick, Jane Wu, Andrew Milich, Mitch Oleson, Mark Pryor, Peter Krogen, Miikka Kangas, Hugh O'Neill
Toward Directed Energy Planetary Defense, Philip Lubin, Gary B. Hughes, J Bible, Jesse Bublitz, Josh Arriola, Caio Motta, Jon Suen, Isabella Johansson, Jordan Riley, Nilou Sarvian, Deborah Clayton-Warwick, Jane Wu, Andrew Milich, Mitch Oleson, Mark Pryor, Peter Krogen, Miikka Kangas, Hugh O'Neill
Statistics
Asteroids and comets that cross Earth’s orbit pose a credible risk of impact, with potentially severe disturbances to Earth and society. We propose an orbital planetary defense system capable of heating the surface of potentially hazardous objects to the vaporization point as a feasible approach to impact risk mitigation. We call the system DE-STAR, for Directed Energy System for Targeting of Asteroids and exploration. The DESTAR is a modular-phased array of kilowatt class lasers powered by photovoltaics. Modular design allows for incremental development, minimizing risk, and allowing for technological codevelopment. An orbiting structure would be developed in stages. The main …
Calculating Ellipse Overlap Areas, Gary B. Hughes, Mohcine Chraibi
Calculating Ellipse Overlap Areas, Gary B. Hughes, Mohcine Chraibi
Statistics
We present an approach for finding the overlap area between two ellipses that does not rely on proxy curves. The Gauss-Green formula is used to determine a segment area between two points on an ellipse. Overlap between two ellipses is calculated by combining the areas of appropriate segments and polygons in each ellipse. For four of the ten possible orientations of two ellipses, the method requires numerical determination of transverse intersection points. Approximate intersection points can be determined by solving the two implicit ellipse equations simultaneously. Alternative approaches for finding transverse intersection points are available using tools from algebraic geometry, …