396 research outputs found
Simulator study of stall/post-stall characteristics of a fighter airplane with relaxed longitudinal static stability
A real-time piloted simulation was conducted to evaluate the high-angle-of-attack characteristics of a fighter configuration based on wind-tunnel testing of the F-16, with particular emphasis on the effects of various levels of relaxed longitudinal static stability. The aerodynamic data used in the simulation was conducted on the Langley differential maneuvering simulator, and the evaluation involved representative low-speed combat maneuvering. Results of the investigation show that the airplane with the basic control system was resistant to the classical yaw departure; however, it was susceptible to pitch departures induced by inertia coupling during rapid, large-amplitude rolls at low airspeed. The airplane also exhibited a deep-stall trim which could be flown into and from which it was difficult to recover. Control-system modifications were developed which greatly decreased the airplane susceptibility to the inertia-coupling departure and which provided a reliable means for recovering from the deep stall
Antenna-coupled TES bolometer arrays for CMB polarimetry
We describe the design and performance of polarization selective
antenna-coupled TES arrays that will be used in several upcoming Cosmic
Microwave Background (CMB) experiments: SPIDER, BICEP-2/SPUD. The fully
lithographic polarimeter arrays utilize planar phased-antennas for collimation
(F/4 beam) and microstrip filters for band definition (25% bandwidth). These
devices demonstrate high optical efficiency, excellent beam shapes, and
well-defined spectral bands. The dual-polarization antennas provide
well-matched beams and low cross polarization response, both important for
high-fidelity polarization measurements. These devices have so far been
developed for the 100 GHz and 150 GHz bands, two premier millimeter-wave
atmospheric windows for CMB observations. In the near future, the flexible
microstrip-coupled architecture can provide photon noise-limited detection for
the entire frequency range of the CMBPOL mission. This paper is a summary of
the progress we have made since the 2006 SPIE meeting in Orlando, FL
Antenna-coupled TES bolometer arrays for CMB polarimetry
We describe the design and performance of polarization selective
antenna-coupled TES arrays that will be used in several upcoming Cosmic
Microwave Background (CMB) experiments: SPIDER, BICEP-2/SPUD. The fully
lithographic polarimeter arrays utilize planar phased-antennas for collimation
(F/4 beam) and microstrip filters for band definition (25% bandwidth). These
devices demonstrate high optical efficiency, excellent beam shapes, and
well-defined spectral bands. The dual-polarization antennas provide
well-matched beams and low cross polarization response, both important for
high-fidelity polarization measurements. These devices have so far been
developed for the 100 GHz and 150 GHz bands, two premier millimeter-wave
atmospheric windows for CMB observations. In the near future, the flexible
microstrip-coupled architecture can provide photon noise-limited detection for
the entire frequency range of the CMBPOL mission. This paper is a summary of
the progress we have made since the 2006 SPIE meeting in Orlando, FL
BICEP3: a 95 GHz refracting telescope for degree-scale CMB polarization
BICEP3 is a 550 mm-aperture refracting telescope for polarimetry of radiation
in the cosmic microwave background at 95 GHz. It adopts the methodology of
BICEP1, BICEP2 and the Keck Array experiments - it possesses sufficient
resolution to search for signatures of the inflation-induced cosmic
gravitational-wave background while utilizing a compact design for ease of
construction and to facilitate the characterization and mitigation of
systematics. However, BICEP3 represents a significant breakthrough in
per-receiver sensitivity, with a focal plane area 5 larger than a
BICEP2/Keck Array receiver and faster optics ( vs. ).
Large-aperture infrared-reflective metal-mesh filters and infrared-absorptive
cold alumina filters and lenses were developed and implemented for its optics.
The camera consists of 1280 dual-polarization pixels; each is a pair of
orthogonal antenna arrays coupled to transition-edge sensor bolometers and read
out by multiplexed SQUIDs. Upon deployment at the South Pole during the 2014-15
season, BICEP3 will have survey speed comparable to Keck Array 150 GHz (2013),
and will significantly enhance spectral separation of primordial B-mode power
from that of possible galactic dust contamination in the BICEP2 observation
patch.Comment: 12 pages, 5 figures. Presented at SPIE Astronomical Telescopes and
Instrumentation 2014: Millimeter, Submillimeter, and Far-Infrared Detectors
and Instrumentation for Astronomy VII. To be published in Proceedings of SPIE
Volume 915
Using systematic data categorisation to quantify the types of data collected in clinical trials: the DataCat project.
BACKGROUND: Data collection consumes a large proportion of clinical trial resources. Each data item requires time and effort for collection, processing and quality control procedures. In general, more data equals a heavier burden for trial staff and participants. It is also likely to increase costs. Knowing the types of data being collected, and in what proportion, will be helpful to ensure that limited trial resources and participant goodwill are used wisely. AIM: The aim of this study is to categorise the types of data collected across a broad range of trials and assess what proportion of collected data each category represents. METHODS: We developed a standard operating procedure to categorise data into primary outcome, secondary outcome and 15 other categories. We categorised all variables collected on trial data collection forms from 18, mainly publicly funded, randomised superiority trials, including trials of an investigational medicinal product and complex interventions. Categorisation was done independently in pairs: one person having in-depth knowledge of the trial, the other independent of the trial. Disagreement was resolved through reference to the trial protocol and discussion, with the project team being consulted if necessary. KEY RESULTS: Primary outcome data accounted for 5.0% (median)/11.2% (mean) of all data items collected. Secondary outcomes accounted for 39.9% (median)/42.5% (mean) of all data items. Non-outcome data such as participant identifiers and demographic data represented 32.4% (median)/36.5% (mean) of all data items collected. CONCLUSION: A small proportion of the data collected in our sample of 18 trials was related to the primary outcome. Secondary outcomes accounted for eight times the volume of data as the primary outcome. A substantial amount of data collection is not related to trial outcomes. Trialists should work to make sure that the data they collect are only those essential to support the health and treatment decisions of those whom the trial is designed to inform
BICEP2 II: Experiment and Three-Year Data Set
We report on the design and performance of the BICEP2 instrument and on its
three-year data set. BICEP2 was designed to measure the polarization of the
cosmic microwave background (CMB) on angular scales of 1 to 5 degrees
(=40-200), near the expected peak of the B-mode polarization signature of
primordial gravitational waves from cosmic inflation. Measuring B-modes
requires dramatic improvements in sensitivity combined with exquisite control
of systematics. The BICEP2 telescope observed from the South Pole with a 26~cm
aperture and cold, on-axis, refractive optics. BICEP2 also adopted a new
detector design in which beam-defining slot antenna arrays couple to
transition-edge sensor (TES) bolometers, all fabricated on a common substrate.
The antenna-coupled TES detectors supported scalable fabrication and
multiplexed readout that allowed BICEP2 to achieve a high detector count of 500
bolometers at 150 GHz, giving unprecedented sensitivity to B-modes at degree
angular scales. After optimization of detector and readout parameters, BICEP2
achieved an instrument noise-equivalent temperature of 15.8 K sqrt(s). The
full data set reached Stokes Q and U map depths of 87.2 nK in square-degree
pixels (5.2 K arcmin) over an effective area of 384 square degrees within
a 1000 square degree field. These are the deepest CMB polarization maps at
degree angular scales to date. The power spectrum analysis presented in a
companion paper has resulted in a significant detection of B-mode polarization
at degree scales.Comment: 30 pages, 24 figure
BICEP2 / Keck Array V: Measurements of B-mode Polarization at Degree Angular Scales and 150 GHz by the Keck Array
The Keck Array is a system of cosmic microwave background (CMB) polarimeters,
each similar to the BICEP2 experiment. In this paper we report results from the
2012 and 2013 observing seasons, during which the Keck Array consisted of five
receivers all operating in the same (150 GHz) frequency band and observing
field as BICEP2. We again find an excess of B-mode power over the
lensed-CDM expectation of in the range
and confirm that this is not due to systematics using jackknife tests and
simulations based on detailed calibration measurements. In map difference and
spectral difference tests these new data are shown to be consistent with
BICEP2. Finally, we combine the maps from the two experiments to produce final
Q and U maps which have a depth of 57 nK deg (3.4 K arcmin) over an
effective area of 400 deg for an equivalent survey weight of 250,000
K. The final BB band powers have noise uncertainty a factor of 2.3
times better than the previous results, and a significance of detection of
excess power of .Comment: 13 pages, 9 figure
Impact of culture towards disaster risk reduction
Number of natural disasters has risen sharply worldwide making the risk of disasters a global concern. These disasters have created significant losses and damages to humans, economy and society. Despite the losses and damages created by disasters, some individuals and communities do not attached much significance to natural disasters. Risk perception towards a disaster not only depends on the danger it could create but also the behaviour of the communities and individuals that is governed by their culture. Within this context, this study examines the relationship between culture and disaster risk reduction (DRR). A comprehensive literature review is used for the study to evaluate culture, its components and to analyse a series of case studies related to disaster risk.
It was evident from the study that in some situations, culture has become a factor for the survival of the communities from disasters where as in some situations culture has acted as a barrier for effective DRR activities. The study suggests community based DRR activities as a mechanism to integrate with culture to effectively manage disaster risk
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