Matsuo Sekine

Weibull-Distributed Ground Clutter

Weibull-distributed ground clutter of cultivated land was measured using an L-band long-range air-route surveillance radar (ARSR) having a 3.0 ¿s pulsewidth and a 1.23° beamwidth at very low grazing angles between 0.21° and 0.32°. It is shown that the shape parameter of the Weibull distribution varied from c = 1.507 to c = 2.0, corresponding to the Rayleigh distribution.

Rain Attenuation 0f Centimeter, Millimeter and Submillimeter Radio Waves

The rain attenuation from 1 to 1000 GHz was calculated by using a Weibu11 distribution for raindrop-size, which was assumed to be caused by coalescence, drop break-up and a chain reaction process. The results showed a good agreement with the recent microwave measurements from 8 to 312.5 GHz.

On Weibull-Distributed Weather Clutter

Weather clutter was observed using an L band range (200nmi) air-route surveillance radar (ARSR). It is shown that the measured clutter amplitudes obey a Weibull distribution.

Suppression of Weibull-Distributed Clutters Using a Cell-Averaging LOG/CFAR Receiver

The parameters of the Weibull distribution and the threshold level for an adaptive CFAR detector are determined by calculating the mean value and the mean-squared value of the input signal voltage before it passes through a logarithmic amplifier. By using this threshold level an adaptive method for suppressing various VVeibull-distributed clutters is proposed.

Computer Aided Analysis of Cell-Cycle Phase from Cytophotometric Histogram

A method for estimating, from cytophotometric data, the proportion of cells in three different phases of the cell cycle is proposed. Computation is done by means of determining seven parameters in the approximate function for the fluorescence intensity histogram. The proportion of cells in the GI, S, and G2-M phases, obtained by this method, was found to be reliable.

Electrical properties of polyimide Langmuir-Blodgett films sandwiched between superconducting electrodes: detection of microwaves

Abstract We have examined the electrical properties of ultrathin insulating layers of cadmium arachidate (C20), polyamic acid long alkyl amine salts (PAA) and polyimide (PI) by using tunnel junctions with structures of (Pb-Bi)/PAA (or C20)/(Pb-Bi), Au/PI/(Pb-Bi) and Au/PI/Au. Typical current-voltage (I-V) characteristics of weakly coupled superconductors were obtained for (Pb-Bi)/PAA (or C20)/(Pb-Bi) junctions with one, two or three deposited layers at a temperature below the critical temperature of a Pb-Bi alloy. On the contrary, typical I-V characteristics of tunnel junctions were obtained for Au/PI/(Pb-Bi) and Au/PI/Au junctions, when the number of deposited layers is greater than about 30. Finally, we concluded that the efficiency of detecting microwaves is excellent in (Pb-Bi)/PAA (or C20)/(Pb-Bi) junctions, although bridging filaments exist in the PAA (or C20) Langmuir-Blodgett (LB) layers, and that the PI LB layers become good electrical insulating spacers when the thickness of deposited layers is more than about 11 nm.

Josephson Junctions Using Polyimide Langmuir-Blodgett Films with a Nb/Au/PI/(Pb-Bi) Structure

We fabricated Josephson junctions with the structure of Nb/Au/PI/(Pb-Bi) using an ultrathin polyimide (PI) Langmuir- Blodgett film as an electrically insulating layer with neither the presence of native oxide layers formed on the base Nb layer nor the dissolution of the base-Nb/Au electrode during the imidization of PAA (Polyamic acid long alkylamine salts) films to produce PI LB films. A typical I-V characteristic of weakly-coupled Josephson junctions was found to be obtained.

Electrical Transport Properties of Josephson Junctions Using Polyimide Langmuir-Blodgett Films

Using thermally stable ultrathin polyimide (PI) Langmuir-Blodgett films, we made tunnel junctions having structures of Nb/PI/(Pb–Bi) and Au/PI/(Pb–Bi). Then we examined the electrical transport properties of the junctions. Here, Nb and Pb-Bi are superconducting electrodes, and Au is a base-(noble metal) electrode. For Nb/PI/(Pb–Bi) junctions, it was found that an inherent oxide layer formed on a base-Nb electrode makes a significant contribution to the electrical conduction through the PI layer and that a typical current-voltage (I-V) characteristic based on the ideal Josephson junction was obtained even when the number of deposited PI layers was zero. For Au/PI/(Pb–Bi) junctions, typical I-V characteristics of tunnel junctions were obtained at a temperature below the critical temperature of a Pb–Bi superconducting alloy only when the number of deposited layers was 27.

Rain Attenuation from Weibull Raindrop-Size Distribution

The rain attenuation from 1 to 1000 GHz was calculated by using a Weibull distribution for raindrop-size. The microwave experimental measurement data from 8 to 312.5 GHz were compared with our calculations. Especially, comparison between the submillimeter measurement and calculation at 312.5 GHz (0.96mm) was shown for the various rainfall rates. The empirical relation A = aRb between the specific attenuation A and the rainfall rate R was also found for a rain temperature of -10°C, 0°C and 20°C, and dependences of a and b on frequencies from 1 to 1000 GHz were tabulated.

CP violation in preon model

SummaryWe propose a composite model in which quarks and leptons are made up of three preons and gauge bosons of two preons. It is then shown thatCP is violated in only one generation of u and d quarks and also in pure leptonic interactions.