Statistical processing method for sidelobe peaks for earth-station antennas

For coordination studies and for the assessment of mutual interference between radiocommunication-satellite systems and between earth stations and radio-relay stations sharing the same frequency band, the method which represents off-axis radiation characteristics of the earth-station antenna is desirable. For this purpose, International Radio Consultative Committee (CCIR) Report 391-4 describes a statistical processing method of sidelobe peaks which was adopted at the XVth Plenary Assembly in 1982. This statistical processing method is based on the slope of reference radiation pattern, while the old one, which has been used, is based on the absolute peak value. Therefore, the results of the statistical evaluation using the current (new) method may differ from that using the old method. According to the measured data on a Cassegrain antenna of 13 m in diameter at about 12 GHz, it is shown that the worst 10 percent value of sidelobe peaks of the new processing method, which is the level exceeded by 10 percent of the peaks, is statistically about 0.8 dB lower than that of the old method.     

A neuron-MOS neural network using self-learning-compatible synapsecircuits

A circuit technology for self-learning neural network hardware has been developed using a high-functionality device called Neuron MOS Transistor (υMOS) as a key circuit element. A υMOS can perform weighted summation of multiple input signals and thresholding all at a single transistor level based on the charge sharing among multiple capacitors. An electronic synapse cell has been constructed with six transistors by merging a floating-gate EEPROM memory cell into a new-concept υMOS differential-source-follower circuitry. The synapse can represent both positive (excitatory) and negative (inhibitory) weights under single V_DD power supply and is free from standby power dissipation. An excellent linearity in the weight updating characteristics of the synapse memory has been also established by employing a simple self-feedback regime in each cell circuitry, thus making it fully compatible to the on-chip self-learning architecture of υMOS neural networks. The basic operation of the synapse cell and a υMOS neural network using the synapse has been experimentally verified using test circuits fabricated by a double-polysilicon CMOS process     

Control of oxidation on NiSix during etching and ashing processes

The oxidation on nickel silicide (NiSi_x) during plasma etching and oxygen ashing is investigated for stable contact resistance on NiSi_x. NiSi_x exposed by various processes is observed by X-ray photoelectron spectroscopy. The oxidation on NiSi_x is promoted by the fluorine that remains during etching and the oxide thickness on n⁺ NiSi_x is greater than that on p⁺ NiSi_x. The remaining fluorine after etching can be decreased by in-situ nitrogen plasma treatment during the post-etching process. Therefore, the oxidation progress with exposure to air and the difference in oxidation on NiSi_x between n⁺ and p⁺ can be suppressed.     

Measurement of Supersonic Jet Noise with Optical Wave Microphone System

An optical wave microphone system is a new technique of sound measurement. This technique has been developed as a new plasma diagnostic technique to measure electron density fluctuations in the nuclear fusion research. Because the sound wave is a pressure or a density fluctuation, it is possible for this technique to measure the sound wave, too. The acoustical characteristics of the optical wave microphone system were examined by using a speaker as a first step. Next, feasibility of this device to measure jet noise was examined. It was found that the optical wave microphone system could measure the jet noise as well as a sound from speaker. Hence the optical wave microphone system can be considered one of the devices equivalent to condenser microphone. Because of these reason, this device is very convenient to scan the acoustic filed through jet flow from the inside to the out side and more preferable for not disturbing the observation field.     

Radiochemical synthesis of silver nanoparticles onto textile fabrics and their antibacterial activity

This paper presents a new technique for synthesizing silver nanoparticles immobilized on textile fabrics using a radiochemical process. In this process, the irradiation of a high-energy electron beam on an aqueous solution containing silver ions induces a reducing reaction that forms metallic silver nanoparticles. Small Ag particles of about 2–4 nm were observed together with relatively large particles of more than 10 nm. These nanoparticles are firmly immobilized on the surface of a support textile fabric without the need for any binder or surfactant. The amount of silver nanoparticles immobilized was found to depend on the water content of the support textile fabric, suggesting that the silver ions are reduced not only by radiochemical species generated by the radiolysis of water, but also by radiochemical species generated in the irradiated support fabric itself. The silver nanoparticles that were immobilized on the support textile fabric exhibited an excellent antibacterial activity across a wide antibacterial spectrum, even after a durability test involving washing the fabric 100 times.     

Integration of equivalence theory and ultra-fine-group slowing-down calculation for resonance self-shielding treatment in lattice physics code GALAXY

A new hybrid resonance self-shielding treatment method in reactor physics field is developed by integrating equivalence theory and ultra-fine-group slowing-down calculation from the theoretical point of view. In the conventional equivalence theory, scattering source approximation and taking no account of resonance interference effect cause prediction error of effective cross-section. By reviewing the derivation scheme of neutron flux in the equivalence theory, the essence of the ultra-fine-group treatment is effectively incorporated. A new form of energy-dependent flux is based on multi-term rational equation, but the scattering source can be solved by the way similar to the slowing-down equation. The accurate non-fuel flux is also considered without direct heterogeneous calculation. The new method can also efficiently eliminate the multi-group condensation error by a semi-analytical reaction rate preservation scheme between ultra-fine and multi-group treatments. The present method is implemented in Mitsubishi Heavy Industries, Ltd. lattice physics code GALAXY. From comparisons of neutronics parameters between GALAXY and a continuous energy Monte-Carlo code, applicability of the new method for lattice physics calculations is confirmed. GALAXY achieves high accuracy with short computation time. Therefore, it can be efficiently applied to generation of the nuclear constants used in the nuclear design and safety analysis of commercial light water reactors.     

Effects of Microstructural Evolution and Dislocation Properties on the Strengthening Behavior of Cold-Drawn Ultralow-Carbon Steel

Metallurgical and Materials Transactions A - The microstructural evolution and variations in the dislocation properties and the dislocation density of drawn ultralow-carbon (ULC) steel wires, which...