Remote probing methods for the determination of the profile of inhomogeneous media

Determining permittivity of inhomogeneous media by remote probing method

Development of theoretical models of integrated millimeter wave antennas

Extensive radiation patterns for Linear Tapered Slot Antenna (LTSA) Single Elements are presented. The directivity of LTSA elements is predicted correctly by taking the cross polarized pattern into account. A moment method program predicts radiation patterns for air LTSAs with excellent agreement with experimental data. A moment method program was also developed for the task LTSA Array Modeling. Computations performed with this program are in excellent agreement with published results for dipole and monopole arrays, and with waveguide simulator experiments, for more complicated structures. Empirical modeling of LTSA arrays demonstrated that the maximum theoretical element gain can be obtained. Formulations were also developed for calculating the aperture efficiency of LTSA arrays used in reflector systems. It was shown that LTSA arrays used in multibeam systems have a considerable advantage in terms of higher packing density, compared with waveguide feeds. Conversion loss of 10 dB was demonstrated at 35 GHz

Near millimeter wave imaging/multi-beam integrated antennas

This report describes the most recent work on the theory of single element Linearly Tapered Slot Antennas (LTSAs) and Constant Width Slot Antennas (CWSAs). The radiation mechanism for these is presently well understood and allows quantitative calculation of beamwidths and sidelobe levels, provided that the antennas have a sufficiently wide conducting region on either side of the tapered slot. Appendices 4 to 7 represent earlier work on the grant. This work further elucidates the properties of arrays of CWSA elements, and the effects of coupling on the beam-shape. It should be noted that typical beam-efficiencies of 65% have been estimated, and that element spacings of about one Rayleigh unit are possible. Further, two-point resolution at the Rayleigh spacing has been demonstrated for a CWSA array in a 30.4 cm paraboloid at 31 GHz. These results underscore that interest in further studies of the radiation mechanism of tapered slot arrays. Appendix 7 constitutes a final, detailed report on the work leading to a 94 GHz seven element LTSA array imaging system, which has been reported previously in less detail. Experimental results are presented

Computation of finite array effects in the framework of the square kilometer array project

The Square Kilometer Array (SKA) is a very large radio telescope being planned by an international consortium. It would operate in a very broad frequency band and have a collecting area of one square kilometer. In order to achieve a good resolution, this area will be spread over a few tens of stations, located several tens or hundreds of kilometers apart. The Netherlands Foundation for Research in Astronomy (ASTRON) is studying the possibility of covering the mid-range frequencies (~0.2 to 2 GHz) with an instrument based on the phased-array technology. This technology presents the major advantages of avoiding mechanically moving structures and of enabling very flexible beamforming. One of the envisaged broadband antenna elements is the tapered slot antenna, also called Vivaldi antenna. The design of these antennas is based on infinite array models, which automatically include the mutual coupling effects. As each station will probably be made of a very large number of small arrays, it is important to know how these arrays will behave when they are truncated. We developed a computation scheme for arrays of antennas made of metallic fins. We justify the adopted approach, then details are given for the fast resolution of the resulting equation system. Finally, examples are shown for wide dipoles and comments are made about the extension to Vivaldi antenna

HIWRAP Radar Development for High-Altitude Operation on the NASA Global Hawk and ER-2

The NASA High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP) is a solid-state transmitter-based, dual-frequency (Ka- and Ku-band), dual-beam (30 degree and 40 degree incidence angle), conical scan Doppler radar system, designed for operation on the NASA high-altitude (20 km) aircrafts, such as the Global Hawk Unmanned Aerial System (UAS). Supported by the NASA Instrument Incubator Program (IIP), HIWRAP was developed to provide high spatial and temporal resolution 3D wind and reflectivity data for the research of tropical cyclone and severe storms. With the simultaneous measurements at both Ku- and Ka-band two different incidence angles, HIWRAP is capable of imaging Doppler winds and volume backscattering from clouds and precipitation associated with tropical storms. In addition, HIWRAP is able to obtain ocean surface backscatter measurements for surface wind retrieval using an approach similar to QuikScat. There are three key technology advances for HIWRAP. Firstly, a compact dual-frequency, dual-beam conical scan antenna system was designed to fit the tight size and weight constraints of the aircraft platform. Secondly, The use of solid state transmitters along with a novel transmit waveform and pulse compression scheme has resulted in a system with improved performance to size, weight, and power ratios compared to typical tube based Doppler radars currently in use for clouds and precipitation measurements. Tube based radars require high voltage power supply and pressurization of the transmitter and radar front end that complicates system design and implementation. Solid state technology also significantly improves system reliability. Finally, HIWRAP technology advances also include the development of a high-speed digital receiver and processor to handle the complex receiving pulse sequences and high data rates resulting from multi receiver channels and conical scanning. This paper describes HIWRAP technology development for dual-frequency operation at high-altitudes using low peak power transmitters and pulse compression. The hardware will be described along with the methods and concepts for the system design. Finally, we will present recent preliminary results from flights on the NASA Global Hawk in support of the NASA Genesis and Rapid Intensification Processes (GRIP) field campaign, and on the NASA ER-2 as fixed nadir pointing mode for the NASA Global Precipitation Measurement (GPM) ground validation (GV) mission - Midlatitude Continental Convective Cloud Experiment (MC3E

Method of moments solution of volume integral equations using parametric geometry modeling

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94709/1/rds4692.pd

The test–retest reliability of four functional mobility tests in apparently healthy adults

Background: Simple field tests are often used to assess functional mobility in clinical settings. Despite having many benefits, these tests are susceptible to measurement error and individual variation. Objectives: To examine the test-retest and absolute reliability of timed up and go test (TUG), five times sit-to-stand (FTSTS), stair climb test (SCT) and 6 minute walk (6MWT). Methods: Over two sessions, thirty-five subjects (30-74 years), repeated the five tests approximately four weeks apart. Test-retest reliability (intraclass correlations [ICC]) and absolute reliability (95% limit of agreements [95% LOA]; standard error of measurement [SEM] and minimum detectable change [MDC]) were calculated. Results: All five tests had high test-retest reliability (ICC > 0.95) although significant between session changes were present for the TUG and FTSTS (p < 0.05). FTSTS displayed the greatest measurement error whilst 95% LOA was the most conservative measure of absolute reliability. Conclusions: The results of this study indicate that the TUG, FTSTS, SCT and 6MWT are reliable when performed four weeks apart. Furthermore, the inclusion of SEM, MDC and 95% LOA provides reference values to aid in identifying changes over time above those of measurement error and individual variation

2013 Colorado forest insect and disease update

The reports describes "an annual investigation of critical forest health issues, including the identification of priority areas across the state where current forest conditions demand timely action." They are intended to "expand Coloradans' knowledge of and interest in our state's forest resources.".Reports produced by the Colorado State Forest Service in conjunction with Colorado Department of Natural Resources, Division of Forestry.Includes bibliographical references.January 2014.Includes the 2013 Colorado forest insect and disease update supplement.The theme of the 2013 report is Caring for Colorado's Forests: Today's Challenges, Tomorrow's Opportunities. How best to care for this vital resource has been a major topic of discussion. This year's report focuses on the values our forests provide and includes several examples of the successful collaborative forest management programs that were created to address the impacts of mountain pine beetle, threats associated with wildfire, and protection of critical watersheds and other values at risk. Hopefully theseexamples will lead to the identification of other potential solutions to the challenges our forests are facing. One thing is clear: forest stewardship is best achieved through the collective efforts of private landowners, public land managers, non-governmentalconservation organizations, elected officials and other interested stakeholders. The mission of the Colorado State Forest Service is to "achieve stewardship of Colorado's diverse forest environments for the benefit of present and future generations." At no time in Colorado's history has the CSFS mission been so relevant - and working with stakeholders to identify and implement innovative programs will help us further our mission