672 research outputs found
Non-Radiative Calibration of Active Antenna Arrays
Antenna arrays offer significant benefits for modern wireless communication systems
but they remain difficult and expensive to produce. One of the impediments of utilising
them is to maintain knowledge of the precise amplitude and phase relationships between
the elements of the array, which are sensitive to errors particularly when each element
of the array is connected to its own transceiver. These errors arise from multiple
sources such as manufacturing errors, mutual coupling between the elements, thermal
effects, component aging and element location errors. The calibration problem of
antenna arrays is primarily the identification of the amplitude and phase mismatch, and
then using this information for correction.
This thesis will present a novel measurement-based calibration approach, which uses a
fixed structure allowing each element of the array to be measured. The measurement
structure is based around multiple sensors, which are interleaved with the elements of
the array to provide a scalable structure that provides multiple measurement paths to
almost all of the elements of the array. This structure is utilised by comparison based
calibration algorithms, so that each element of the array can be calibrated while
mitigating the impact of the additional measurement hardware on the calibration
accuracy. The calibration was proven in the investigation of the experimental test-bed,
which represented a typical telecommunications basestation. Calibration accuracies of
±0.5dB and 5o were achieved for all but one amplitude outlier of 0.55dB. The
performance is only limited by the quality of the coupler design. This calibration
approach has also been demonstrated for wideband signal calibration
Space Station Planetology Experiments (SSPEX)
A meeting of 50 planetary scientists considered the uses of the Space Station to support experiments in their various disciplines. Abstracts (28) present concepts for impact and aeolian processes, particle formation and interaction, and other planetary science experiments. Summaries of the rationale, hardware concepts, accomodations, and recommendations are included
CUPID pre-CDR
CUPID is a proposed future tonne-scale bolometric neutrinoless double beta
decay () experiment to probe the Majorana nature of neutrinos
and discover Lepton Number Violation in the so-called inverted hierarchy region
of the neutrino mass. CUPID will be built on experience, expertise and lessons
learned in CUORE, and will exploit the current CUORE infrastructure as much as
possible. In order to achieve its ambitious science goals, CUPID aims to
dramatically reduce the backgrounds in the region of interest introducing a
high efficiently / discrimination techniques, also demonstrated
by the CUPID-0 and CUPID-Mo experiments, and using a high transition energy
double beta decay nucleus, Mo. This document describe the main concepts
related with the design of the CUPID experiment and indicates the projected
sensitivities and the global scientific goal of the experiment
2020 NASA Technology Taxonomy
This document is an update (new photos used) of the PDF version of the 2020 NASA Technology Taxonomy that will be available to download on the OCT Public Website. The updated 2020 NASA Technology Taxonomy, or "technology dictionary", uses a technology discipline based approach that realigns like-technologies independent of their application within the NASA mission portfolio. This tool is meant to serve as a common technology discipline-based communication tool across the agency and with its partners in other government agencies, academia, industry, and across the world
Aeronautical engineering: A continuing bibliography with indexes (supplement 295)
This bibliography lists 581 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System in Sep. 1993. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics
Advances in Measuring the Apparent Optical Properties (AOPs) of Optically Complex Waters
This report documents new technology used to measure the apparent optical properties (AOPs) of optically complex waters. The principal objective is to be prepared for the launch of next-generation ocean color satellites with the most capable commercial off-the-shelf (COTS) instrumentation. An enhanced COTS radiometer was the starting point for designing and testing the new sensors. The follow-on steps were to apply the lessons learned towards a new in-water profiler based on a kite-shaped backplane for mounting the light sensors. The next level of sophistication involved evaluating new radiometers emerging from a development activity based on so-called microradiometers. The exploitation of microradiometers resulted in an in-water profiling system, which includes a sensor networking capability to control ancillary sensors like a shadowband or global positioning system (GPS) device. A principal advantage of microradiometers is their flexibility in producing, interconnecting, and maintaining instruments. The full problem set for collecting sea-truth data--whether in coastal waters or the open ocean-- involves other aspects of data collection that were improved for instruments measuring both AOPs and inherent optical properties (IOPs), if the uncertainty budget is to be minimized. New capabilities associated with deploying solar references were developed as well as a compact solution for recovering in-water instrument systems from small boats
NASA Tech Briefs, April 1997
Topics covered include: Video and Imaging; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Life Sciences; Books and Reports
Technical accomplishments of the NASA Lewis Research Center, 1989
Topics addressed include: high-temperature composite materials; structural mechanics; fatigue life prediction for composite materials; internal computational fluid mechanics; instrumentation and controls; electronics; stirling engines; aeropropulsion and space propulsion programs, including a study of slush hydrogen; space power for use in the space station, in the Mars rover, and other applications; thermal management; plasma and radiation; cryogenic fluid management in space; microgravity physics; combustion in reduced gravity; test facilities and resources
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