1,944 research outputs found
Measurement of the dynamic response of the CERN DC spark system and preliminary estimates of the breakdown turn-on time
The new High Repetition Rate (HRR) CERN DC Spark System has been used to
investigate the current and voltage time structure of a breakdown. Simulations
indicate that vacuum breakdowns develop on ns timescales or even less. An
experimental benchmark for this timescale is critical for comparison to
simulations. The fast rise time of breakdown may provide some explanation of
the particularly high gradients achieved by low group velocity, and narrow
bandwidth, accelerating structures such as the T18 and T24. Voltage and current
measurements made with the previous system indicated that the transient
responses measured were dominated by the inherent capacitances and inductances
of the DC spark system itself. The bandwidth limitations of the HRR system are
far less severe allowing rise times of approximately 12ns to be measured
An Application of Con-Resistant Trust to Improve the Reliability of Special Protection Systems within the Smart Grid
This thesis explores an application of a con-resistant trust mechanism to improve the performance of communications-based special protection systems to further enhance their effectiveness and resiliency. New initiatives in the energy sector are paving the way for the emergent communications-based smart grid technology. Smart grids incorporate modern technologies in an effort to be more reliable and efficient. However, with the benefits of this new technology comes added risk. This research utilizes a con-resistant trust mechanism as a method to quickly identify malicious or malfunctioning protection system nodes in order to mitigate the resulting instabilities in the smart grid. The feasibility and performance of this trust architecture is demonstrated through experiments comparing a simulated special protection system implemented with a con-resistant trust mechanism and without via an analysis of variance statistical model. The simulations yield positive results when implementing the con-resistant trust mechanism within the communications-based special protection system for the smart grid
Investigation of nest predation as a cause of turtle population declines on the Sequoyah National Wildlife Refuge, Oklahoma
Investigators of a turtle population study spanning 19 years reported major declines in capture rates of red-eared sliders (Trachemys scripta; 4.05 to 0.44) and Ouachita map turtles (Graptemys ouachitensis; 0.18 to 0.01) populations within Sequoyah National Wildlife Refuge in Vian, Oklahoma. Although capture rates of alligator snapping turtles (Macrochelys temminckii) collected in 2016 were comparable to those found in a 1997-2000 study (0.33 compared to 0.35), there was concern that the cause(s) of observed declines in smaller, shorter-lived turtle species could also impact alligator snapping turtle populations, and may not yet be apparent due to differences in life histories, such as longevity and age of sexual maturity.
Artificially constructed nests and trail cameras helped determine that nest predation, a common cause of turtle mortality is extremely high along six tributaries within the refuge (100%). Raccoons (Procyon lotor) were the most common nest predators, contributing to 71% of all nest predation. Alligator snapping turtle captures were higher in tributaries with higher nest predation suggesting that alligator snapping turtles may be contributing further to turtle mortalities. To alleviate the high rates of nest predation, the refuge should take action to manage common turtle nest predators, as well as investigate alligator snapping turtles as an additional turtle predator
Chesapeake Bay blue crabs and consumption related illness
Currently, 72.2% of the Chesapeake Bay is impaired due to pollutants that impaired water quality. Some common pollutants in the Bay that are also toxic if consumed are: polychlorinated biphenyls (PCBs), mercury, and lead. Pollutants tend to settle on the Bay floor and become accumulate in the sediment. Most shellfish and small finfish live near or on the Bay floor and are may be exposed to high levels of pollutants. Therefore, bioaccumulation and biomagnification of pollutants can occur in shellfish and finfish tissues. These pollutants may cause a risk to human health by either increasing the risk of developing cancer or through systemic toxicity. Blue crabs were collected from James Madison University’s property in Bluff Point, Virginia and sent to REIC Lab in Verona, Virginia to be analyzed for PCBs, mercury, and lead. Data from Virginia’s Department of Environmental Quality’s Fish Tissue Monitoring Program was also analyzed. Using the concentrations of lead, mercury, and PCBs in the blue crab tissue, a risk assessment was done to determine the human health risks of consuming blue crabs from the Chesapeake Bay. The results show that consumption of blue crabs from the Chesapeake Bay can cause an increased risk of developing cancer due to PCBs and a risk of systemic toxicity from lead
The asteroseismological potential of the pulsating DB white dwarf stars CBS 114 and PG 1456+103
We have acquired 65 h of single-site time-resolved CCD photometry of the
pulsating DB white dwarf star CBS 114 and 62 h of two-site high-speed CCD
photometry of another DBV, PG 1456+103. The pulsation spectrum of PG 1456+103
is complicated and variable on time scales of about one week and could only
partly be deciphered with our measurements. The modes of CBS 114 are more
stable in time and we were able to arrive at a frequency solution somewhat
affected by aliasing, but still satisfactory, involving seven independent modes
and two combination frequencies. These frequencies also explain the discovery
data of the star, taken 13 years earlier. We find a mean period spacing of 37.1
+/- 0.7 s significant at the 98% level between the independent modes of CBS 114
and argue that they are due to nonradial g-mode pulsations of spherical degree
l=1. We performed a global search for asteroseismological models of CBS 114
using a genetic algorithm, and we examined the susceptibility of the results to
the uncertainties of the observational frequency determinations and mode
identifications (we could not provide m values). The families of possible
solutions are identified correctly even without knowledge of m. Our optimal
model suggests Teff = 21,000 K and M_* = 0.730 M_sun as well as log(M_He/M_*) =
-6.66, X_O = 0.61. This measurement of the central oxygen mass fraction implies
a rate for the ^12C(alpha,gamma)^16O nuclear reaction near S_300=180 keV b,
consistent with laboratory measurements.Comment: 10 pages, 10 embedded figures, 3 embedded tables. Accepted for
publication in MNRA
The Data Processing Pipeline for the Herschel-HIFI Instrument
The HIFI data processing pipeline was developed to systematically process
diagnostic, calibration and astronomical observations taken with the HIFI
science instrumentas part of the Herschel mission. The HIFI pipeline processed
data from all HIFI observing modes within the Herschel automated processing
environment, as well as, within an interactive environment. A common software
framework was developed to best support the use cases required by the
instrument teams and by the general astronomers. The HIFI pipeline was built on
top of that and was designed with a high degree of modularity. This modular
design provided the necessary flexibility and extensibility to deal with the
complexity of batch-processing eighteen different observing modes, to support
the astronomers in the interactive analysis and to cope with adjustments
necessary to improve the pipeline and the quality of the end-products. This
approach to the software development and data processing effort was arrived at
by coalescing the lessons learned from similar research based projects with the
understanding that a degree of foresight was required given the overall length
of the project. In this article, both the successes and challenges of the HIFI
software development process are presented. To support future similar projects
and retain experience gained lessons learned are extracted.Comment: 18 pages, 5 figure
Smooth operator? Understanding and visualising mutation bias
The potential for mutation operators to adversely affect the behaviour of evolutionary algorithms is demonstrated for both real-valued and discrete-valued genotypes. Attention is drawn to the utility of effective visualisation techniques and explanatory concepts in identifying and understanding these biases. The skewness of a mutation distribution is identified as a crucial determinant of its bias. For redundant discrete genotype-phenotype mappings intended to exploit neutrality in genotype space, it is demonstrated that in addition to the mere extent of phenotypic connectivity achieved by these schemes, the distribution of phenotypic connectivity may be critical in determining whether neutral networks improve the ability of an evolutionary algorithm overall. Mutation operators lie at the heart of evolutionary algorithms. They corrupt the reproduction of genotypes, introducing the variety that fuels natural selection. However, until recently, the process of mutation has taken..
The Cost of Criminal Justice in West Virginia
The National Commission on Law Observance and Enforcement, generally known as the Wickersham Commission, is popularly associated with prohibition, as critic, protagonist, propagandist, or apologist, depending upon the point of view. The more fundamental aspects of its work have escaped popular attention. The first two reports dealt with the problem of national prohibition. Twelve more were devoted to other phases of crime and its treatment. Here attention is to be devoted to the Report on the Cost of Crime in an effort to determine the economic burden through taxation, private expenditures, and economic loss which results from the necessity of suppressing crime and correcting the criminal in modern society? The tremendous scope of this project is apparent to the most casual observer. Innumerable jurisdictions throughout the states are attempting, each in its own way with varying costs and equally varying success, to eliminate crime. The sheer expense of this effort must be a matter of wide concern. The determination of the cost of the administration of criminal justice reveals little aside from the approximate drain upon economic resources due to the perversity of humanity. It indicates, moreover, little of importance with regard to the absolute or even the comparative effectiveness of the governmental agency which happens to be the object of the expenditure. The infinite variety of conditions, not alone throughout the states, but even among the cities of the same state, makes practically barren any attempt to match against each other the cost elements of different jurisdictions. Such comparisons reveal only resultant conditions, but the causal factors are beclouded with influences beyond the application of statistical methods. To imply in variations of expense definite elements of causation would require that all factors be reduced to a basis of absolute equality. This is not possible. The degree of effectiveness of the discharge of governmental functions must, therefore, be measured in some other way. Cheap government is not necessarily good government, nor is costly government necessarily inefficient. False economy often masquerades as efficiency. The attempt to determine cost is limited to the measurement of what the crime bill of the nation is. Whether to accomplish the desired result it should be more or less than present figures show is quite another matter. The purpose of this paper is to assemble and present the elements of criminal cost which bear upon the State of West Virginia. The present writers co6perated with the directors of the national investigation of the cost of crime in studying conditions in certain municipalities of the State. At this time the results, hardly to be termed conclusions, are presented, together with other pertinent material which has been taken from the extensive national report. At the risk of incurring justifiable criticism for exaggerating the implications of these statistics, it is suggested that further study along these lines may contribute to a better planned and more effective administration of criminal justice in the wider field of social benefit in the State of West Virginia
Spectroscopic characterization and detection of Ethyl Mercaptan in Orion
New laboratory data of ethyl mercaptan, CHCHSH, in the millimeter
and submillimeter-wave domains (up to 880 GHz) provided very precise values of
the spectroscopic constants that allowed the detection of
-CHCHSH towards Orion KL. 77 unblended or slightly blended
lines plus no missing transitions in the range 80-280 GHz support this
identification. A detection of methyl mercaptan, CHSH, in the spectral
survey of Orion KL is reported as well. Our column density results indicate
that methyl mercaptan is 5 times more abundant than ethyl mercaptan in
the hot core of Orion KL.Comment: Accepted for publication in ApJL (30 January 2014)/ submitted (8
January 2014
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