30,036 research outputs found
Retransmission of water resources data using the ERTS-1 data collection system
There are no author-identified significant results in this report
Analysis and geological interpretation of gravity data from GEOS-3 altimeter
A number of detailed gravimetric geoids of portions of the world's oceans from marine gravity measurements were constructed. The geoids were constructed by computing 1 x 1 deg or 10 x 10 deg averages of free-air anomaly data and subtracting these values from currently used satellite derived Earth models. The resulting difference gravity anomalies are then integrated over a sphere using a simplified form of Stoke's equation to obtain a difference geoid. This difference geoid is added to the satellite derived model to obtain a 1 x 1 deg or 10 x 10 deg total gravimetric geoid. The geoid undulations are studied by comparison of the altimeter measurements with the morphology of the ocean floor. Utilizing a combination of altimetry data, gravity and seismic reflection data, geophysical models of the earth can be constructed
S-band antenna phased array communications system
The development of an S-band antenna phased array for spacecraft to spacecraft communication is discussed. The system requirements, antenna array subsystem design, and hardware implementation are examined. It is stated that the phased array approach offers the greatest simplicity and lowest cost. The objectives of the development contract are defined as: (1) design of a medium gain active phased array S-band communications antenna, (2) development and test of a model of a seven element planar array of radiating elements mounted in the appropriate cavity matrix, and (3) development and test of a breadboard transmit/receive microelectronics module
Surface chemistry of major rock types of Sonora Pass Test Site, California
Chemical study of selected rock samples tabulated as oxide percentage
JPL microwave experiment support
Geological parameter effects on remote microwave radiometer response
An evaluation of the first year experience from the mature students' perspective; a multi-institutional comparison
This study investigates the experiences of mature students across three higher education institutions in the UK. The issues arising are of relevance to academics who are involved in widening participation and in evaluating support in their own
programmes for the diversity of students. The sample includes mature students from programmes in Health, where mature students form a majority, and in Business, where mature students formed a minority. Focus groups were used
to gain access to student perspectives on expectations, motivations, sacrifices, transitions, induction, programmes and assessment. The findings include misleading information that did not acknowledge the particular concerns and
needs of mature students, induction processes that were not experienced as inclusive by mature students, and varying experiences of support but overall the institutional context was significant
Ground data investigations Mt. Lassen, site 56-mission 76
Microwave radiometry and infrared photography for meteorological dat
Learning through research: the first year experience from the mature students perspective
This collaborative work from St Martin’s College, Salford and Middlesex Universities brings together experiences of mature students, (21+ years of age on entry), in a phenomenological
piece of research identifying the different ways in which they feel supported in their undergraduate studies. There is particular value to the collaborative aspect of this research
as it pulls together the differences in management and structures from a higher education college, a pre-1992 and post-1992 institutions.
This paper aims to highlight the findings of the research at a point in time to feature the concerns of mature students on entering and the transition into HE, to demonstrate what
mature students attribute to encouraging them to succeed and persist in their studies, learning ‘what works’ type strategies from the three institutions and devising new strategies to support not only this particular group of students, but all during their undergraduate studies
Oxygen diffusion and reactivity at low temperature on bare amorphous olivine-type silicate
The mobility of O atoms at very low temperatures is not generally taken into
account, despite O diffusion would add to a series of processes leading to the
observed rich molecular diversity in space. We present a study of the mobility
and reactivity of O atoms on an amorphous silicate surface. Our results are in
the form of RAIRS and temperature-programmed desorption spectra of O2 and O3
produced via two pathways: O + O and O2 + O, investigated in a submonolayer
regime and in the range of temperature between 6.5 and 30 K. All the
experiments show that ozone is formed efficiently on silicate at any surface
temperature between 6.5 and 30 K. The derived upper limit for the activation
barriers of O + O and O2 + O reactions is 150 K/kb. Ozone formation at low
temperatures indicates that fast diffusion of O atoms is at play even at 6.5 K.
Through a series of rate equations included in our model, we also address the
reaction mechanisms and show that neither the Eley Rideal nor the Hot atom
mechanisms alone can explain the experimental values. The rate of diffusion of
O atoms, based on modeling results, is much higher than the one generally
expected, and the diffusive process proceeds via the Langmuir-Hinshelwood
mechanism enhanced by tunnelling. In fact, quantum effects turn out to be a key
factor that cannot be neglected in our simulations. Astrophysically, efficient
O3 formation on interstellar dust grains would imply the presence of huge
reservoirs of oxygen atoms. Since O3 is a reservoir of elementary oxygen, and
also of OH via its hydrogenation, it could explain the observed concomitance of
CO2 and H2O in the ices.Comment: 28 pages, 14 figure
Improving the Functional Control of Aged Ferroelectrics using Insights from Atomistic Modelling
We provide a fundamental insight into the microscopic mechanisms of the
ageing processes. Using large scale molecular dynamics simulations of the
prototypical ferroelectric material PbTiO3, we demonstrate that the
experimentally observed ageing phenomena can be reproduced from intrinsic
interactions of defect-dipoles related to dopant-vacancy associates, even in
the absence of extrinsic effects. We show that variation of the dopant
concentration modifies the material's hysteretic response. We identify a
universal method to reduce loss and tune the electromechanical properties of
inexpensive ceramics for efficient technologies.Comment: 6 pages, 3 figure
- …