The estimation of pointing angle and normalized surface scattering cross section from GEOS-3 radar altimeter measurements

The statistical error of the pointing angle estimation technique is determined as a function of the effective receiver signal to noise ratio. Other sources of error are addressed and evaluated with inadequate calibration being of major concern. The impact of pointing error on the computation of normalized surface scattering cross section (sigma) from radar and the waveform attitude induced altitude bias is considered and quantitative results are presented. Pointing angle and sigma processing algorithms are presented along with some initial data. The intensive mode clean vs. clutter AGC calibration problem is analytically resolved. The use clutter AGC data in the intensive mode is confirmed as the correct calibration set for the sigma computations

Considerations for the design of an onboard air traffic situation display

The basic concept of remoting information to the cockpit is used to design and develop a computerized airborne traffic situation display device that automatically selects and presents segments of a controller's scope to the aircraft pilot via a narrow band digital data link. These data are integrated with aircraft heading and navigation information to provide a display useful in congested air space. The display can include alphanumerical symbols, air route maps, and controller instructions

Electrical properties of Bi-implanted amorphous chalcogenide films

The impact of Bi implantation on the conductivity and the thermopower of amorphous chalcogenide films is investigated. Incorporation of Bi in Ge-Sb-Te and GeTe results in enhanced conductivity. The negative Seebeck coefficient confirms onset of the electron conductivity in GeTe implanted with Bi at a dose of 2x1016 cm-2. The enhanced conductivity is accompanied by defect accumulation in the films upon implantation as is inferred by using analysis of the space-charge limited current. The results indicate that native coordination defects in lone-pair semiconductors can be deactivated by means of ion implantation, and higher conductivity of the films stems from additional electrically active defects created by implantation of bismuth.Comment: This is an extended version of the results presented in Proc. SPIE 8982, 898213 (2014

Trajectory shifts in the Arctic and Subarctic freshwater cycle

Author Posting. © The Author(s), 2006. This is the author's version of the work. It is posted here by permission of American Association for the Advancement of Science for personal use, not for redistribution. The definitive version was published in Science 313 (2006): 1061-1066, doi:10.1126/science.1122593.Manifold changes in the freshwater cycle of high-latitude lands and oceans have been reported in the past few years. A synthesis of these changes in sources of freshwater and in ocean freshwater storage illustrates the complementary and synoptic temporal pattern and magnitude of these changes over the past 50 years. Increasing river discharge anomalies and excess net precipitation on the ocean contributed ~20,000 km3 of fresh water to the Arctic and high latitude North Atlantic oceans from lows in the 1960s to highs in the 1990s. Sea ice attrition provided another ~15,000 km3, and glacial melt added ~2000 km3. The sum of anomalous inputs from these freshwater sources matched the amount and rate at which fresh water accumulated in the North Atlantic during much of the period from 1965 through 1995. The changes in freshwater inputs and ocean storage occurred in conjunction with the amplifying North Atlantic Oscillation and rising air temperatures. Fresh water may now be accumulating in the Arctic Ocean and will likely be exported southward if and when the North Atlantic Oscillation enters into a new high phase.Funding was provided by NSF (grants OPP-0229302, OPP- 0436118, OPP-0327664, OPP-0352754, OPP-0519840, OCE- 0326778), ONR (grant N00014-02-1-0305) and NASA (grant IDS-03-0000-0145)

Conventional versus automated measurement of blood pressure in primary care patients with systolic hypertension: randomised parallel design controlled trial

Objective To compare the quality and accuracy of manual office blood pressure and automated office blood pressure using the awake ambulatory blood pressure as a gold standard

Molecular and morphometric variation in European populations of the articulate brachiopod <i>Terebeatulina retusa</i>

Molecular and morphometric variation within and between population samples of the articulate brachiopod &lt;i&gt;Terebratulina&lt;/i&gt; spp., collected in 1985-1987 from a Norwegian fjord, sea lochs and costal sites in western Scotland, the southern English Channel (Brittany) and the western Mediterranean, were measured by the analysis of variation in the lengths of mitochondrial DNA (mtDNA) fragments produced by digestion with nine restriction endonucleases and by multivariate statistical analysis of six selected morphometric parameters. Nucleotide difference within each population sample was high. Nucleotide difference between population samples from the Scottish sites, both those that are tidally contiguous and those that appear to be geographically isolated, were not significantly different from zero. Nucleotide differences between the populations samples from Norway, Brittany, Scotland and the western Mediterranean were also very low. Morphometric analysis confirmed the absence of substantial differentiation

Development of a Dynamic Water Management Policy for Texas

The purpose of this investigation was to develop techniques to assist water planners in the optimum implementation of their plans. Specifically, techniques useful for continual evaluation of water plans and for scheduling the sequence and timing of needed project additions were sought. Considerable effort has been directed toward developing water plans for meeting long range needs for water both in Texas and around the United States. These long range water plans have consisted of fixed systems of development projects deemed necessary at some future point in time - usually 50 years. Plans such as these are considered flexible guides to serve as water development goals. However, water planners also need implementation plans which specify the sequence and timing of construction for specific projects which are a part of the long range water plan. Previous researchers have studied the application of operations research and optimization techniques in the planning of fixed systems to meet water needs at specific times in the future. This investigation seeks the development of optimization techniques which can be used by planners and developing implementation plans. In this research, techniques were studied to determine those which best met the research objectives. A stochastic programming formulation for obtaining an operating policy for single, multi-purpose reservoirs based on the continuity equation, stochastic inflow and demand, and chance constraints was developed. The chance constraints were converted to an equivalent linear programming problem. This formulation was then extended to a linked system of multi-purpose reservoirs. Both linear and quadratic objective functions were used with the equivalent linear constraint set. The problem facing water resource planners during implementation of water plans was then addressed. The objective used in this problem was to select reservoir storage capacities, schedule a time for construction, and establish an operating policy such that the total cost of the linked reservoir system is minimized. In solving this problem which is in fact a mixed integer-continuous linear programming problem, an analyst defines the feasible reservoir segments in storage capacity for each time period in which expansion is possible. The resulting problem size and general structure lend themselves well to the use of a specialized decomposition technique. Use of this decomposition technique permits the problem to be separated into a linear programming problem and an integer programming problem. This approach makes the problem more computationally tractable

North Atlantic ocean circulation and abrupt climate change during the last glaciation

The most recent ice age was characterized by rapid and hemispherically asynchronous climate oscillations, whose origin remains unresolved. Variations in oceanic meridional heat transport may contribute to these repeated climate changes, which were most pronounced during marine isotope stage 3, the glacial interval 25 thousand to 60 thousand years ago. We examined climate and ocean circulation proxies throughout this interval at high resolution in a deep North Atlantic sediment core, combining the kinematic tracer protactinium/thorium (Pa/Th) with the deep water-mass tracer, epibenthic δ13C. These indicators suggest reduced Atlantic overturning circulation during every cool northern stadial, with the greatest reductions during episodic Hudson Strait iceberg discharges, while sharp northern warming followed reinvigorated overturning. These results provide direct evidence for the ocean’s persistent, central role in abrupt glacial climate change

Protecting the UK Infrastructure: A System to Detect GNSS Jamming and Interference

Abstract The vulnerability of space based position navigation and timing (PNT) systems to RF interference sources is becoming well known outside of the traditional PNT sector for example, into the critical infrastructure operations area. Risk managers of organisations in this area are becoming aware of the vulnerabilities and dependencies in using space based PNT systems. This paper presents work performed and work on-going in the UK, to develop capabilities that provide detection and early warning for operators of critical infrastructure and law enforcement agencies (LEA), to the presence of RF interference in the bands associated with space based PNT. These capabilities can detect and will be able to locate source(s) of RF interference which allows infrastructure operators and LEA to take advantage of quality of service and trust concepts when applied to these space based PNT systems. This paper also presents a case study of the detection of an intentional RF interference device, which impacted upon one organisation&apos;s critical infrastructure

The structure of the extreme Schwarzschild-de Sitter space-time

The extreme Schwarzschild-de Sitter space-time is a spherically symmetric solution of Einstein's equations with a cosmological constant Lambda and mass parameter m>0 which is characterized by the condition that 9 Lambda m^2=1. The global structure of this space-time is here analyzed in detail. Conformal and embedding diagrams are constructed, and synchronous coordinates which are suitable for a discussion of the cosmic no-hair conjecture are presented. The permitted geodesic motions are also analyzed. By a careful investigation of the geodesics and the equations of geodesic deviation, it is shown that specific families of observers escape from falling into the singularity and approach nonsingular asymptotic regions which are represented by special "points" in the complete conformal diagram. The redshift of signals emitted by particles which fall into the singularity, as detected by those observers which escape, is also calculated.Comment: 19 pages, 10 figures, LaTeX, to appear in Gen. Rel. Gra