The Circular Synthetic Radar

A new type of synthetic radar, the circular synthetic radar, uses a simple interferometer whose elements are mounted at the ends of a horizontal boom rotating about a vertical mast. Pulses are radiated alternately ?in-phase? and in ?phase-quadrature.? The returning echoes are also detected incoherently, both ?in-phase? and in ?phase-quadrature.? The four distinct outputs are fed into an on-line computer which, after a Fourier analysis, synthesizes a mapping function of the azimuthal distribution of targets.     

Angular Accuracy of a Scanning Radar Employing a Two-Pole Filter

A two-pole filter is proposed as a detector for a scanning radar. The optimum values of the filter coefficients are found and are approximated by a simple expression. The optimum two-pole filter requires a 0.15-dB increase in signal-to-noise ratio in order to provide the same detection capability as the optimum detector, and yields azimuth estimates whose standard deviation are within 15 percent of the Cramér-Rao lower bound. The estimator is simple to implement, avoiding the storage requirements of the moving window detector and the bias complications of the feedback integrator.     

Closed-Form Expressions for Noncoherent Radar Integration Gain and Collapsing Loss

Closed-form formulas allow rapid determination of noncoherent integration gain and integration loss when the single-sample IF signal-to-noise ratio (SNR) is known. In addition, if the required SNR is known for any number of integrated pulses, the required SNR for any other number is easily determined. A closed-form expression is given for radar collapsing loss, expressed in terms of the equivalent integrated signal-to-noise ratio required to produce a given combination of false-alarm and detection probabilities. Alternatively, the single-sample signal-to-noise ratio of a set of samples may be used together with the closed-form expression for integration gain to get the equivalent integrated signal-to-noise ratio.     

Analysis of Multimodal Systems

The estimation of a multimodal linear system whose mode-to-mode transitions are described by a finite-state Markov chain is described. The problem has application in studying separation standards in an air traffic control environment. An optimal solution is formulated which is computationally infeasible. A suboptimal estimator is then derived which closely approximates the optimal estimator. An example is presented to illustrate the technique.     

Charge exchange lifetimes for ring current ions

In applying the charge exchange mechanism to ion phenomena within the Earth's magnetosphere it is critical to the proper interpretation of observations that the charge exchange lifetimes for the ions be known as accurately as possible. Various new results have been published which significantly modify the charge exchange lifetimes which have been used in space physics research during the past decade and a half. Some of the newer results have been used in the application of the charge exchange decay mechanism but the use has been limited and for the most part incomplete. The neutral hydrogen density distribution now yields lifetimes which are shorter than previously calculated, while the functional dependence of the lifetimes on pitch angle provides for slower decay for ions mirroring off the geomagnetic equator. This review coalesces and summarizes the latest and best measurements of the physical quantities involved in the complete calculation of the charge exchange lifetime of the mirroring magnetospheric ions.     

Some early results of the keV plasma experiment on GEOS-1

Some preliminary new results are presented of the keV plasma experiment on GEOS-1. Electrons and ions have been observed to stream along the magnetic field lines in the dayside magnetosphere from the ionospheric side of the satellite towards the equatorial plane during magnetic storms, with streaming velocities corresponding to a kinetic energy of the order of a keV. The opposite streaming velocity has also been seen, but primarily in the ions only and with a smaller flux ratio for the two opposite directions along the field lines. The transition between the two opposite streaming directions, as seen by the satellite, has been found to occur even in a fraction of a second.In magnetic storm conditions azimuthal asymmetries in ion fluxes corresponding to electric field intensities of several tens of millivolts per meter have been observed.     

Radar Cross Section of Ships

A laboratory method to determine the magnitude and position of radar reflection sources on complex targets is described. In addition the method provides a way to measure the modification of the radar cross section (RCS) due to multipath. The method has application in modeling RCS for radar and electronic countermeasure (ECM) system performance analysis and in the study of the extent to which the signature of the target could be altered. The equipment described, termed MACROSCOPE, was developed for RCS studies by the U.S. Army and is described in limited distribution bution literature. The application to marine targets is new with this paper, as is the technique of measuring the RCS of parts of the target and analytically combining them to represent the whole. An illustration of the need for this type of laboratory equipment was illustrated by the extensive search for full scale data which could be compared to scale model data to validate the technique.     

The Engineer as a Radical?

Outdated and rigorous curricula are not only producing engineers unsuited to the challenges of the 1970's, but they are scaring off many of the most creative and intelligent students. Engineering education has become an endurance test; the excitement has been lost. Most students strive only to get out. Engineering schools have not yet realized the importance of the involvement of engineers in current environmental problems. They continue to present only the dry technical courses and seem unconcerned about the student's sense of social perspective or his motivation. This paper proposes a freshman awareness seminar plus project oriented learning in the following years as a remedy for this sad situation.     

Inactivation, mutation induction and repair in Bacillus subtilis spores irradiated with heavy ions.

Studies on the response of bacterial spores to accelerated heavy ions (HZE particles) help in understanding problems of space radiobiology and exobiology. Layers of spores of Bacillus subtilis strains, differing in repair capabilities, were irradiated with accelerated boron, carbon and neon ions of linear energy transfer (LET) values up to 14000 MeV cm2/g. Inactivation as measured by loss of colony forming ability and induction of mutations as measured by reversion to histidine prototrophy and resistance to 150 micrograms/ml sodium azide were tested, as well as the influence of repair processes on these effects. For inactivation, the cross-sectional values sigma plotted as a function of LET follow a saturation curve. The plateau, which is reached around a LET of 2000 MeV cm2/g, occurs at 2.5 x 10(-9) cm2, a value in good agreement with the dimensions of the spore protoplast. Lethal damage produced at LET values < 2000 MeV cm2/g is reparable. Recombination repair is more effective than excision repair. At higher LET values, lethal damage could not be reconstituted by the repair mechanisms studied. In addition, at these high LET values, the frequency of induced mutations was drastically decreased. The data support the assumption of at least two qualitatively different types of lesion, depending on the LET of the affecting heavy ion.