375 research outputs found
Compact operators
All compact operators have a representation analogous to that
for compact normal operators. As a partial converse we obtain conditions which
allow one to construct a large number of such operators. Using the results in
the paper, we answer a number of questions about the decomposition of a compact
into real and imaginary parts
Spatial variability of wave fields over the scale of a wave energy test site
Accurate wave measurements are required for wave energy applications,
including resource assessments and performance assessments. In response,
wave data are measured from deployment sites, commonly using wave buoys
or other point wave sensors. Spatial variability in the wave field will introduce
inaccuracies to the analysis of data captured from a single point to
represent a separate location or area. This thesis describes research undertaken
to quantify the effect of spatial variability on the accuracy of direct
wave measurements taken at a wave energy site. An array of four timesynchronised
wave buoys were deployed, separated by 500m, in a location
close to the Wave Hub wave energy test site in Cornwall, UK. These data
were subject to close scrutiny in terms of data processing and quality control,
which raised specific issues regarding data processing and the validation
of wave data for a new measurement facility. Specific recommendations are
made for data captured from this facility, and bespoke quality control routines
were developed. This process minimises the possible contribution of
errors to the processed data, which is observed to be of the highest importance
when analysing simultaneous data sets, and provides a data set that is
particularly suited to the examination of the spatial characteristics of ocean
waves. The differences between simultaneous data demonstrated local physical
processes to be causing a deterministic difference between the waves at
the measurement sites, which contributed to a significant difference between
the power statistics at different locations within the site. Instantaneous differences
between measurements were observed to agree well with theoretical
estimations of random error, based on sampling theory. The culmination of
the research is a unique analysis of the spatial properties of ocean wave fields
on the scale of a wave energy test site, of direct relevance to the development
and monitoring of wave energy test sites.SWRDA and ERDF through the PRIMaRE projec
Extensions of an functional calculus
On a reflexive Banach space , if an operator admits a functional
calculus for the absolutely continuous functions on its spectrum , then this functional calculus can always be extended to
include all the functions of bounded variation. This need no longer be true on
nonreflexive spaces. In this paper, it is shown that on most classical
separable nonreflexive spaces, one can construct an example where such an
extension is impossible. Sufficient conditions are also given which ensure that
an extension of an \AC functional calculus is possible for operators acting
on families of interpolation spaces such as the spaces
Storage stability of whole and nibbed, conventional and high oleic peanuts (<i>Arachis hypogeae </i>L.)
Peanuts are increasingly being used as nibbed ingredients in cereal bars, confectionery and breakfast cereals. However, studies on their oxidative stability in this format are limited. Storage trials to determine the stability to oxidation were carried out on whole and nibbed kernels of conventional (CP) and high oleic (HOP) peanuts, with respect to temperature and modified atmosphere packaging. HOP exhibited the highest oxidative stability, with a lag phase in whole kernels of 12–15 weeks before significant oxidation occurred. HOP also showed higher levels of intrinsic antioxidants, a trolox equivalent antioxidant capacity (TEAC) of 70 mMol equivalence and radical scavenging percentage (RSP) of 99.8 % at the beginning of storage trials, whereas CP showed values of 40 mMol and 81.2 %, respectively. The intrinsic antioxidants at the beginning of these storage trials were shown to affect the peroxide value (PV), where RSP and TEAC decreased, and PV increased. Therefore, in peanuts the processing format (nibbed or whole) had the highest influence on susceptibility of lipid oxidation, highest to lowest importance: processing format > temperature > atmospheric conditions
Regional stability versus fine-scale changes in community composition of mesotrophic grasslands over 25 years
Ella Morton - wifehttps://stars.library.ucf.edu/cfm-ch-memoranda-1930/1334/thumbnail.jp
A semicoherent glitch-robust continuous gravitational wave search
Continuous gravitational-wave signals from isolated non-axisymmetric rotating
neutron stars may undergo episodic spin-up events known as glitches. If
unmodelled by a search, these can result in missed or misidentified detections.
We outline a semicoherent glitch-robust search method that allows
identification of glitching signal candidates and inference about the model
parameters.Comment: 9 pages, 6 figures, 2 table
Spatial variability of ocean waves, from in-situ measurements
notes: Detailed statistical analysis of unique concurrent wave measurements Physical processes distort natural homogeneity of waves at typical wave energy site Physical processes can have a significant effect on wave energy assessments Differences greatest for low freq’s, 8.6% difference in Mean incident wave power Short-term spatial variability was largest for high-frequencies, and parameter Tm02publication-status: Publishedtypes: ArticleThis paper describes the analysis of the spatial properties of ocean waves using measurements from an array of four directional wave buoys installed in a square formation, with side 500 m, in the Celtic Sea, UK. Wave measurements in this area have been installed to support resource assessment and design for wave energy devices at the Wave Hub site off the North Cornwall coast. This unique deployment of multiple directional sensors provides high quality direct measurements of the spatial properties of the wave field. Spectral parameters measured simultaneously by all four buoys within the array are compared and it is demonstrated that wave conditions cannot be considered stationary across the measurement area. Differences in the measured wave fields were observed primarily in the low frequencies and are observed to be of a level sufficient to impact the assessment of site characteristics. Theoretical estimations of refraction and bottom friction indicate that these physical processes contribute to the observed measurements. The results demonstrate the potential effect of spatial variability in wave fields on the monitoring of wave energy sites, and highlight the requirement for accurate evaluation of physical processes
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