Optimal Control of a Nuclear Power Reactor Core with a Coupled Nuclear Thermo-hydrodynamics Model

An optimal control is giyen for regulating power distribution in a nuclear power reactor which has cylindrical geometry. The space dependence of the system is described by expanding space depenident variables by Helmholtz modes. Results are obtained through the principle of optimality and are described by the Riccati-type algebraic equation that the optimal feedback coefficients should satisfy. Use of an integral equation as the system equation makes it possible to deal with actual controlling apparatuses: control rods or rod clusters

Improvement of Etalon-fringe Immunity in Diode-laser Derivative Spectroscopy

In a sensitive spectrometry with lead-salt diode lasers, etalon-fringe phenomena often intervene in the measured absorption spectrum. Derivative methods are employed for the purpose of high resolution where the pertaining wavelength is modulated. This paper presents results of mathematical examination on a possible improvement of immunity from the etalon-fringes by choosing the profile of the wavelength modulation

Modeling of gapped power bus structures for isolation using cavity modes

Power bus resonance characteristics of a gapped power-plane with a slit and a split power-plane with a gap were studied, using a fast algorithm based on a full cavity-mode resonator model and the segmentation method. Inductance and capacitance models were used to account for a field coupling along the slit and across the gap, respectively. Good agreements between the calculated and measured results were found to demonstrate the effectiveness and accuracy of our fast algorithm and the segmentation method, as well as the inductance model for the slit and the capacitance model for the gap. </p

Fast Spectrometry System with Using Tunable Laser Diode

Basic prohlems are discussed about a local, realtime and very sensitive air-pollution monitoring using a laser diode. The method employs the second derivative spectrometry replacing the incoherent light source and mechanical choppers in a traditional method with the laser diode and a newly developed electronic system. Etalon fringes at this system becomes the dominant noise source and its statistic and dynamical features are to be understood. Numerical examination was done for the optimal width of optical frequency modulation. A very fast measurement of weak absorption spectra became possible by the development of lock-in-amplifiers with finite integration time instead of a low-pass filter. Spectra of methane in 7.6 μm region and a time-dependent spectrum of the etaIon fringe are shown

Convergence acceleration and accuracy improvement in power bus impedance calculation with a fast algorithm using cavity modes

Based on the cavity-mode model, we have developed a fast algorithm for calculating power bus impedance in multilayer printed circuit boards. The fast algorithm is based on a closed-form expression for the impedance Z matrix of a rectangular power bus structure; this expression was obtained by reducing the original double infinite series into a single infinite series under an approximation. The convergence of the single series is further accelerated analytically. The accelerated single summation enables much faster computation, since use of only a few terms is enough to obtain good accuracy. In addition, we propose two ways to compensate for the error due to the approximation involved in the process of reducing the double series to the single series, and have demonstrated that these two techniques are almost equivalent

Quasi-random Scanning of a Digitally Controlled Spectrometry

A quasi-random method for spectral scanning is proposed to reduce an alias response to a quick change in the source abundance. A direct application is made for an atmospheric methane monitoring with a current-tunable diode laser. Only barrel shift methods are examined being found further vulnerable to drifting etalon fringes

Experimental Collimation of Cerenkov SHG Blue Laser Beam with a Cylindric Mirror

A cylindric mirror was used, in place of a parabolic mirror, to collimate the crescent blue laser beam radiated from the Cerenkov SHG in channel waveguide configuration. The cylindric mirror radius is requested to be twice the focal length of the parabolic mirror. The focusing effect of the cylindric mirror in collimation can be compensated by slightly lifting the mirror in its normal direction. Under the condition that the mirror was declined by 5.56° and lifted by 25 μm, we got the　collimated beam with divergence angle less than 1.3 mrad. In the focusing experiment, the collimated beam was focused with spotsize of 1.8 μm. The details on the analysis and experiment are reported

Accuracy and Etalon Fringe Phenomena in Methane-gas Spectrometry Employing Tunable Diode Lasers

A method to monitor atmospheric gas concentration employing a tunable diode laser is proposed. An apparatus was built and experiments were made. The tunable diode laser employed was of'PbSnTe with its wavenumber about 1200 cm(-1) at a temperature of 77 K. Methane concentration in laboratory atmosphere was measured on the experiments. The inquired gas-density is obtained by a hardwired microcomputer incorporating the measured absorption spectrum over a prescribed range instead of an absorption at a single wavenumber. By this, drift type noises are suppressed. After an analysis based on experimental data, an attainable sensitivity for methane was found to be 1 ppb.m. This value may increase if an etalon fringe interference exists. The natural concentration, about 1 ppm, of atmospheric methane was actually measured with a short optical path of only one meter

Optical Circuit for Waveform-synthesis with Utilizing both GaAs- and Si-Optoelectronic Switches

This paper presents an optical-waveform synthesizer as one of the applications of optical bistable devices. This device is advantageous in terms of faster operation in which width of each pulse obtained is down to the order of subnanosecond, because this device employs both GaAs- and Si-optoelectronic switches as photodetector. Optical pulse shaping as a preliminary experiment is also described

Absorption Spectrum Measurement for Atmospheric Level Nitric Monoxide in γ-0 Band and Its Density Deduction

An absorption spectrum of γ-0 band of nitric monoxide of very dilute density was taken. An experimental electronic device showed a distinguishing power of 0.01 ppm through 10 m optical pathlength. By the aid of a data processing based on a principle developed by the authors, this sensitivity does not suffer from coexisting sulfur dioxide, which shares the absorption band with the nitric monoxide