Electron acceleration by single and double laser beams

The longitudinal electric field of single and double Gaussian laser beams are used to accelerate electrons. The longitudinal field of the single beam is concentrated on the axis and is favourable for acceleration. A set of two beams is considered. Beams run parallel, collinearly, overlap partially and have a phase difference iπ in between. As a result, the transverse components of fields cancel each other while the longitudinal components are double-fold. In both schemes, the electrons are accelerated in lengths of the Rayleigh range, which is common to the plasma-based accelerators.     

Gel chromism and anomalous luminescence in poly(3-alkylthiophene)

The absorption spectrum of poly(3-alkylthiophene) gel changes drastically in association with a volume instability upon changing the solvent composition and also the temperature. In the expanded state in chloroform and at high temperature, the photoluminescence is much enhanced compared with the shrunken state in ethanol and at low temperature. This gel chromism and anomalous luminescence are discussed in terms of the change of effective conjugation length induced by the steric hindrance and the dynamics of the photoexcited species.     

Air gap flux analysis for cage rotor diagnosis

The relationship between the magnetomotive force distribution of a three-phase induction motor and various cage rotor faults, such as broken bars and end rings, is discussed in detail. Search coil output and its harmonic components are analyzed to allow the determination of faults from the air-gap flux density. The results obtained in tests on a motor into which faults were intentionally introduced confirm the effectiveness of this method of analysis.     

Structural study of degraded ZnMgSSe blue light emitters

Using electroluminescence (EL) topography and transmission electron microscopy (TEM), we investigated the nonluminescent regions which form while current is being injected into ZnMgSSe/ZnSSe/ZnCdSe-based blue light emitters. Small dark spots were observed just after turn-on and spread out forming rough nonluminescent triangles in the <100> directions in the EL image of the active region. TEM studies showed that the small dark spots are pre-existing stacking faults originating at the substrate/epitaxial layer interface. The nonluminescent triangles were found to be a dense region of dislocation dipoles and dislocation loops. Each dipole was aligned along two <110> directions in the {111} planes. The Burgers vectors were of the type a/2<011> inclined at 45° to the (001) junction plane.     

Trace elements in human transitory milk. Variation caused by biological attributes of mother and infant

Multielement analysis was performed on human milk collected on 5-9-d postpartum from 51 Japanese females using inductively coupled plasma (ICP) mass spectrometry (MS), ICP atomic emission spectrometry (ICP-AES) and fluorometry. Thirty-one elements were detected by these analytical methods in milk. Twelve elements (Na, Mg, P, S, K, Ca, Cu, Zn, Se, Sr, Rb, and Mo) were detected in all of the samples. Al, Cs, and Ba were the elements detected by ICP-MS in more than half of the samples. Multiple regression analysis extracted biological attributes of mother and infant, such as maternal stature, maternal wt, or infant's birth wt, as statistically significant factors contributing to the variation in elemental concentration in milk. However, the rates of contribution were small in all cases. It was concluded that the biological attributes of mother and infant examined in this study were not the major factors that contribute to elemental variation in human milk.     

Distributed architecture for energy management D-structure

Electric power systems are expanding in size and complexity, and the requirement for the energy management system (EMS) is becoming more important. In this computer control system, a single control computer is used mainly as the primary computer and its software is very complicated because of its hugh number of small, quick tasks to obtain high response speed. Therefore, much effort is needed to develop and modify the programs, and the responsiveness of this centralized architecture varies greatly when many faults occur in the power system. This paper describes a new distributed architecture for the EMS. Distributed processors execute the functions cooperatively with periodic access to the common bulletin board database in which information about the power system exist. This architecture facilitates the software development and maintenance, and it also enhances the performance by the parallel processing of the distributed functions.     

Experimental study on optically band-limited 40-Gb/s RZ signals with optically time-division demultiplexing receiver

The impact of optical filtering on 40-Gb/s return-to-zero (RZ) signals was experimentally investigated with an optically time-division multiplexing (OTDM) receiver. Through the evaluation of the signal performance by changing the interpulse-phase conditions of the symmetrically band-limited 40-Gb/s signals, we have confirmed that similar performance was obtained regardless of the interpulse-phase condition, owing to the pulse-reshaping capability of an OTDM receiver. A performance comparison was also conducted between symmetrically and asymmetrically filtered 40-Gb/s RZ signals. It was found that the symmetrically filtered signal was more tolerant for the dispersion-compensation error, while the asymmetrically filtered signal was more tolerant for fiber nonlinearity with optical filters that have a 3-dB bandwidth of 45 GHz.