In the past few years, there has been much interest at JPL in the investigation and development of efficient signal arraying techniques. As JPL missions begin to adopt Ka-band (32-GHz) for downlink communications, and the mechanical control and structural integrity of large antennas approach their limits, using advanced signal processing to array smaller antennas becomes a cost effective and fl...

We present the first experimental results on waveguide-type all-NbN SIS receivers fabricated on MgO substrates designed in a frequency range from 780 to 960 GHz. The receiver has a resonant distributed SIS junction one wavelength long at 870 GHz as the tuning circuit and a diagonal feed horn. The mixer chip was fabricated with accuracies of less than 10 im in width and +/5 jam in thickness by o...

An ultrasonic planar horn with a Bézier profile is developed. The first longitudinal displacement mode of the horn is exploited for high displacement amplification in order to reduce the penetration force required to enter and cut materials. The displacement amplification and stress distribution characteristics of the Bézier horn and the commonly used catenary horn are examined. The penetration...

There have been a number of publications in recent years on generalising the AGM paradigm to the Horn fragment of propositional logic. Most of them focused on adapting AGM contraction and revision to the Horn setting. It remains an open question whether the adapted Horn contraction and Horn revision are interdefinable as in the AGM case through the Levi and Harper identities. In this paper, we ...

A design study has been performed for a lightweight, cylindrical array antenna for a hostile-mortar-locating radar system. A mathematical model of the array was developed which permitted tradeoff studies to be made of various array parameters. Data computed using the model compared very well with experimental and other theoretical data. Critical components of the array were built and tested and...

Resting cyst and motile thecate cell stages of three heterotrophic Protoperidinium oblongum, Protoperidinium sp and Protoperidinium claudicans were assessed. Cysts were isolated from sediment collected from southeast coast of Iran. Individual live cysts were incubated under optimal conditions for germination. Results showed that Protoperidinium oblongum cysts were pentagonal smooth walled and t...

In this paper, we study issues on disjunctions of propositional Horn theories. In particular, we consider deciding whether a disjunction of Horn theories is Horn, and, if not, computing a Horn core, i.e., a maximal Horn theory included in this disjunction. The problems are investigated for different representations of Horn theories, namely for Horn CNFs and characteristic models. While the prob...