Testing the Independence of Nonhomogeneous Rayleigh Clutter

Two attractive real-time implementation tests are presented that discriminate between correlated and uncorrelated clutter. A clutter model is assumed in which the envelope distribution within a cell is Rayleigh, but the mean clutter level fluctuates from cell to cell. Both the tests utilize observations made in pairs on two clutter envelopes corresponding to two consecutive azimuth sweeps. The results are applicable to real-time testing of the effectiveness of various decorrelation techniques employed by radar systems.     

The giant planets and their satellites: Report on the Cospar Symposium,Ottawa, Canada,May 18–21, 1982

A $\text{Symposium on the Giant Planets and Their Satellites}$ was presented in conjunction with the Twenty-fourth Plenary Meeting of the Committee on Space Research. This paper summarizes the talks presented and places the remaining papers of this volume in context.     

Heavy ion action on yeast cells: inhibition of ribosomal-RNA synthesis, loss of colony forming ability and induction of mutants.

The action of heavy ions (Ar to U) accelerated to specific energies up to about 10 MeV/u (u=atomic mass unit) on different functions of yeast cells was studied. Ribosomal-RNA synthesis is inhibited according to a single-hit mechanism. Inactivation cross-sections were linearly related to the ratio of the squares of the effective charge Z* and the velocity of the ions. It is concluded from the analysis that the range of the most energetic delta-electrons is larger than previously assumed. There is no such dependence for survival and induction of mutants. In both cases cross-sections increase with the ion's specific-energy indicating an important contribution of long-range delta-electrons. The analysis shows that diploid yeast is not killed by a single-hit mechanism even by very heavy ions if the track width is too small. The relative importance of the penumbral region is even more pronounced with the more sensitive strains.     

Utility of landsat data in mineral exploration — a case study from Orissa,India

The utility of Landsat data in geosciences has been established beyond doubt. In this paper utility of Landsat data in mineral exploration has been highlighted.The geologic and geomorphic interpretation of Landsat data brought out two very significant and characteristic features in scene 152-046 in the southern part of Orissa. One was distinct tonal anomaly and other was occurance of flat planated surface devoid of vegetation and drainage on top of hills. This when checked on ground at Gandhmardan was found to be bauxite bearing lateritic plateau. When this known information was extrapolated over other regions in scenes 151-046 and 152-046, all other bauxitic — lateritic plateaus were picked up very easily on Landsat imagery.The information was further extrapolated in the southern scene No.152-047 where without doing much detailed geologic and geomorphic interpretation almost all other bauxitic — lateritic bodies occuring in the region were picked up. This proves the utility of Landsat data in mineral exploration.Moreover delineation of extent of such bodies could be done very accurately on Landsat imagery thus saving considerable time in the exploration programme.     

Uniform Sampling Analysis of a Hybrid Phase-Locked Loop with a Sample-and-Hold Phase Detector

Phase-locked-loop (PLL) bit synchronizers often employ integrate-and-dump type phase detectors that provide phase error information only at discrete points in time. Usually these phase detectors are followed by sample-and-hold circuits to produce a stairstep error voltage as the input to a standard analog circuit loop filter. When the loop is configured in this manner, it is referred to as a hybrid PLL. Sampled-data analysis methods (Z transforms) are used to determine the stability and transient response of this loop.     

WAMDII — A wide angle Michelson Doppler imaging interferometer for spacelab

A CCD imaging device has been designed which combines a spatial resolution of 0.1° with a spectral resolving power of 10⁵, sufficient to measure Doppler shifts and line widths of individual atmospheric emission lines. It will be flown aboard Spacelab and will be used to study neutral winds and temperatures as functions of height, latitude and time of day.     

The Resolution Performance of Range Estimators

The theoretical basis and methods of implementation of a moment algorithm for the range separation estimation of two closely spaced point targets are presented. Moment estimation and noise filtering techniques introduced here result in a considerable improvement over Baum's algorithm. The error bounds are established and it is shown that the spectral moment estimator exhibits optimum (zero bias, minimum variance) performance when the target separation normalized to the standard deviation of the Gaussian pulse is 2?1.5. Monte Carlo simulation is performed to verify the approximations made and to demonstrate the feasibility of the working models.     

Comparison of resonant topologies in high-voltage DC applications

Because of their tolerance of transformer nonidealities, resonant converters are considered to be well-suited to high-voltage applications. The series and parallel resonant topologies, as well as a newly discovered hybrid resonant topology are compared for high-voltage applications. Design criteria which incorporate transformer nonidealities are developed and used in the construction of high voltage prototypes for each topology. It is found that the parallel topology leads to the lowest peak switch current and the most ideal behavior     

The Magellan project

Magellan is one of the future space projects being studied by the European Space Agency. The aim is to provide high resolution (λ/Δλ ≥ 2.5 × 10⁴) spectra in the far and extreme UV (between 500 and 1550 Å) of faint galactic and extragalactic objects (V ≤ 16^m). The instrument consists of a mechanical collimator, a concave holographic grating and a bidimensional photon-counting detector. A low resolution mode (λ/Δλ ≥ 10³) will provide spectra of objects as faint as 18^m.5. Magellan is planned as an observatory, operated in real time, and allowing interaction with the observer.     

Structure of the Martian atmosphere from ε-Gem occultation observations

We have collected information about Martian atmospheric scale heights derived from observations of the occultation of ? Gem by Mars on April 8, 1976. The observations give data in the altitude range ～50 to 80 km. A rough, unweighted average of results so far available yields a temperature of ～165°K. Excursions of ～±40°K about this mean may be present as a function of both altitude and areographic coordinates.