3,923 research outputs found
Timing Mark Detection on Nuclear Detonation Video
During the 1950s and 1960s the United States conducted and filmed over 200 atmospheric nuclear tests establishing the foundations of atmospheric nuclear detonation behavior. Each explosion was documented with about 20 videos from three or four points of view. Synthesizing the videos into a 3D video will improve yield estimates and reduce error factors. The videos were captured at a nominal 2500 frames per second, but range from 2300-3100 frames per second during operation. In order to combine them into one 3D video, individual video frames need to be correlated in time with each other. When the videos were captured a timing system was used that shined light in a video every 5 milliseconds creating a small circle exposed in the frame. This paper investigates several method of extracting the timing from images in the cases when the timing marks are occluded and washed out, as well as when the films are exposed as expected. Results show an improvement over past techniques. For normal videos, occluded videos, and washed out videos, timing is detected with 99.3%, 77.3%, and 88.6% probability with a 2.6%, 11.3%, 5.9% false alarm rate, respectively
Machine Learning Nuclear Detonation Features
Nuclear explosion yield estimation equations based on a 3D model of the explosion volume will have a lower uncertainty than radius based estimation. To accurately collect data for a volume model of atmospheric explosions requires building a 3D representation from 2D images. The majority of 3D reconstruction algorithms use the SIFT (scale-invariant feature transform) feature detection algorithm which works best on feature-rich objects with continuous angular collections. These assumptions are different from the archive of nuclear explosions that have only 3 points of view. This paper reduces 300 dimensions derived from an image based on Fourier analysis and five edge detection algorithms to a manageable number to detect hotspots that may be used to correlate videos of different viewpoints for 3D reconstruction. Furthermore, experiments test whether histogram equalization improves detection of these features using four kernel sizes passed over these features. Dimension reduction using principal components analysis (PCA), forward subset selection, ReliefF, and FCBF (Fast Correlation-Based Filter) are combined with a Mahalanobis distance classifiers to find the best combination of dimensions, kernel size, and filtering to detect the hotspots. Results indicate that hotspots can be detected with hit rates of 90% and false alarms ÂĄ 1%
Intelligent infrastructures systems for sustainable urban environment
Extensive research is now under way around the world to develop advanced technologies to enhance the performances of infrastructure systems. While these technological advances are incremental in nature, they will eventually lead to structures which are distinctly different from the actual infrastructure systems. These new structures will be therefore capable of Structural Health Monitoring (SHM), involving applications of electronics and smart materials, aiming to assist engineers in realizing the full benefits of structural health monitoring.intelligent infrastructures, environment, optimization
Emittance Dilution in 1 and 5 TeV 30 GHz Linear Colliders
In this paper, we describe the single and multi-bunch sources of emittance dilution in the linacs of both 1 and 5 TeV center-of-mass energy linear colliders. The linacs operate at high rf accelerating gradients with a frequency around 30 GHz. At this high accelerating frequency, the wakefields are very strong and we discuss the BNS damping and correction procedures as well as the alignment and construction tolerances that are required to preserve the transverse emittance. Finally, because the collider must operate with long bunch trains, we consider the multi-bunch emittance dilution for a few cases where either the long-range transverse wakefield is damped or it is decreased by a combination of weak damping and detuning
Predicting spatial spread of rabies in skunk populations using surveillance data reported by the public
Background:
Prevention and control of wildlife disease invasions relies on the ability to predict spatio-temporal dynamics and understand the role of factors driving spread rates, such as seasonality and transmission distance. Passive disease surveillance (i.e., case reports by public) is a common method of monitoring emergence of wildlife diseases, but can be challenging to interpret due to spatial biases and limitations in data quantity and quality.
Methodology/Principal findings:
We obtained passive rabies surveillance data from dead striped skunks (Mephitis mephitis) in an epizootic in northern Colorado, USA. We developed a dynamic patch-occupancy model which predicts spatio-temporal spreading while accounting for heterogeneous sampling. We estimated the distance travelled per transmission event, direction of invasion, rate of spatial spread, and effects of infection density and season. We also estimated mean transmission distance and rates of spatial spread using a phylogeographic approach on a subsample of viral sequences from the same epizootic. Both the occupancy and phylogeographic approaches predicted similar rates of spatio-temporal spread. Estimated mean transmission distances were 2.3 km (95% Highest Posterior Density (HPD95): 0.02, 11.9; phylogeographic) and 3.9 km (95% credible intervals (CI95): 1.4, 11.3; occupancy). Estimated rates of spatial spread in km/year were: 29.8 (HPD95: 20.8, 39.8; phylogeographic, branch velocity, homogenous model), 22.6 (HPD95: 15.3, 29.7; phylogeographic, diffusion rate, homogenous model) and 21.1 (CI95: 16.7, 25.5; occupancy). Initial colonization probability was twice as high in spring relative to fall.
Conclusions/Significance:
Skunk-to-skunk transmission was primarily local (< 4 km) suggesting that if interventions were needed, they could be applied at the wave front. Slower viral invasions of skunk rabies in western USA compared to a similar epizootic in raccoons in the eastern USA implies host species or landscape factors underlie the dynamics of rabies invasions. Our framework provides a straightforward method for estimating rates of spatial spread of wildlife diseases
Simulation Package based on Placet
The program PLACET is used to simulate transverse and longitudinal beam effects in the main linac, the drive-beam accelerator and the drive-beam decelerators of CLIC, as well as in the linac of CTF3. It provides different models of accelerating and decelerating structures, linear optics and thin multipoles. Several methods of beam-based alignment, including emittance tuning bumps and feedback, and different failure modes can be simulated. An interface to the beam-beam simulation code GUINEA-PIG exists. Currently, interfaces to MAD and TRANSPORT are under development and an extension to transfer lines and bunch compressors is also being made. In the future, the simulations will need to be performed by many users, which requires a simplified user interface. The paper describes the status of PLACET and plans for the futu
Fairness criteria through the lens of directed acyclic graphical models
A substantial portion of the literature on fairness in algorithms proposes,
analyzes, and operationalizes simple formulaic criteria for assessing fairness.
Two of these criteria, Equalized Odds and Calibration by Group, have gained
significant attention for their simplicity and intuitive appeal, but also for
their incompatibility. This chapter provides a perspective on the meaning and
consequences of these and other fairness criteria using graphical models which
reveals Equalized Odds and related criteria to be ultimately misleading. An
assessment of various graphical models suggests that fairness criteria should
ultimately be case-specific and sensitive to the nature of the information the
algorithm processes
Livestock abundance predicts vampire bat demography, immune profiles, and bacterial infection risk
Human activities create novel food resources that can alter wildlifeâpathogen interactions. If resources amplify or dampen, pathogen transmission probably depends on both host ecology and pathogen biology, but studies that measure responses to provisioning across both scales are rare. We tested these relationships with a 4-year study of 369 common vampire bats across 10 sites in Peru and Belize that differ in the abundance of livestock, an important anthropogenic food source. We quantified innate and adaptive immunity from bats and assessed infection with two common bacteria. We predicted that abundant livestock could reduce starvation and foraging effort, allowing for greater investments in immunity. Bats from high-livestock sites had higher microbicidal activity and proportions of neutrophils but lower immunoglobulin G and proportions of lymphocytes, suggesting more investment in innate relative to adaptive immunity and either greater chronic stress or pathogen exposure. This relationship was most pronounced in reproductive bats, which were also more common in high-livestock sites, suggesting feedbacks between demographic correlates of provisioning and immunity. Infection with both Bartonella and haemoplasmas were correlated with similar immune profiles, and both pathogens tended to be less prevalent in high-livestock sites, although effects were weaker for haemoplasmas. These differing responses to provisioning might therefore reflect distinct transmission processes. Predicting how provisioning alters hostâpathogen interactions requires considering how both within-host processes and transmission modes respond to resource shifts
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