High Frequency Interference Research Articles

Gaussian beam effects in far-field in-line holography

Far-field in-line holography has been studied in detail when one or both of the beams used for recording and reconstruction are Gaussian. The contrast of the high frequency interference fringes and hence their recordability have been investigated with a specific example of the object having circular cross section. For reconstruction the effects of uniform as well as Gaussian beams are studied and compared.

Computer Control of Basic and Applied Experiments in Spark Emission Spectroscopy

A hardware system is described which provides for software-independent timing of events necessary for the smooth operation of an adjustable waveform spark source. Illustrative cases are given showing the extension of this system into a single-channel spectrometer and a complex schlieren photography experiment. Software outlines are also provided. The use of an optical coupler and a fiber optic are shown to improve system performance greatly in high radio frequency interference environments.

Study of Sintered Electrodes for Mercury Vapour Lamps

Processing method of sintered electrodes for mercury vapour lamps was investigated. The results obtained were as follows:A mercury vapour lamp with sintered electrode exhibited a lower high frequency interference, a lower required ignition voltage and a longer life compared with that with spiral electrodes previously used.These effects are caused by the fact that a lower thermal conductivity and much greater amount of emitter materials are obtained in the sintered electrode compared with the characters involved in the spiral electrode.Because of the application of powder metallurgical method, sintered electrodes with good quality can be readily and economically manufactured.

Halbleiter-Wechselstrom-Stellglieder für Die Temperaturregelung an Kunststoffverarbeitungsmaschinen

With the majority of extruders currently in use, dualmode temperature control is employed. Electrical power is supplied to the resistance or induction heaters by means of electromagnetic contactors chiefly for the reason of simplicity and low cost. However, switching the power circuits by mechanical contacts can cause high frequency interference problems during both closing and opening of the contacts. Contact bounce, random contact opening, and sharp interruption of inductive circuits can lead to high induced voltage transients, contact arcing, dielectric breakdown and associated phenomena presenting severe disadvantages. The advent of advanced process control systems as well as process computers makes more versatile equipment, which allows continuous variation of the average power to the heaters, a necessity. The solution could be solid-state AC power actuators based upon variable-pulse-length switching control of thyristors (silicon controlled rectifiers and triacs) in conjunction with sophisticated integrated circuits. The paper describes a device which passes a variable number of full cycles of the AC supply in an specified period. This period may be made quite short, about two seconds or less, so that if a heater having a fairly large thermal capacity is used, power will appear to be varied continuously. Zero-crossing techniques are employed forcing the solid-state switch to close at the instant when the voltage across it is zero, and to open at the instant when the current through it is zero. The variation of average power to the heaters is linearly dependent on the actuator input signal which is 4 to 20 mA DC supplied by the output of continuousaction process controllers. A simplified version of the device, intended for use in conjunction with process computers or other digital equipment, operates in the on-off mode controlled by logic input signals. In both cases the input of the actuator is isolated from AC power.

New Conductor Shielding for Lo-Hi Electromagnetic Interference Control

This paper discusses a new electromagnetic interference (EMI) shielding for conductors. The shielding was especially developed to contain or exclude interference energy initiated by both magnetic and electrical fields over a broad frequency range. Incorporating a unique shielding concept, the new shielding minimizes (1) interference propagation from power or signal wiring, (2) low to high frequency (60 c/s to 10 Ge/s) interference pickup from external sources, and (3) requirements for segregation and special routing of power and signal wiring and interconnecting cables. Composed of two or more layers of braided magnetic materials, the shielding has demonstrated significant improvements in shielding effectiveness compared with conventional shielding over standard conductors and coaxial cables. In-service use has attested to its effectiveness.

溶鉄中のチタン脱酸

The interrelations among titanium, oxygen in liquid iron and deoxidation products at 1550°, 1600° and 1650*deg;C were studied.In this experiment, two effective techniques were developed. One is the use of a thermocouple protected from high frequency interference by an Mo tube inserted for the automatic temperature control and measurement. The other is the application of the Peeling method for the sampling of the deoxidation products for identification.The following results were obtained.(1) Primary deoxidation products:Corresponding the contents of titanium in liquid iron, a few kinds of the primary deoxidation products were identified as follows.Ti3O5 (anosovite): 0.001<[%Ti]<0.2Ti2O3 (α-Al2O3 type): 0.2<[%Ti]<2At higher titanium contents TiO seems to be produced.(2) Deoxidation equilibrium constant:In the range of 0.001 to 0.1% Ti and at 1550 to 1650, the reaction was as follows.Ti3O5 (s) =3Ti+5O log K′=-41, 470/T+3.40

Examples of Optical Analysis and Filtering of Seismic Record Sections: ABSTRACT

When coherent light from a laser beam is passed through a transparent reduction of a variable-density or variable-area record section, the seismic signals act as an optical grating to produce a diffraction pattern which is the two-dimensional Fourier transform of the section itself. By using suitable lenses, the diffraction pattern can be converted into an image of the original section. By obstructing portions of the pattern corresponding End_Page 1086------------------------------ to particular frequencies or dips on the section, one can remove such frequencies or dips from the reconstructed image. This is the basis for a new technique of optical filtering which United Geophysical Corporation has designated as LaserScan. With this optical processing technique, the first step is an examination of the spectrum of the data. This technique lends itself well to the analysis and evaluation of the information on the seismic record sections being processed. Such a study commonly suggests optimum positions for filtering settings. Examples are given of this, and of the effects of some of the suggested filtering. A number of seismic record sections are shown before and after filtering. The various examples show the enhancement of reflection data previously confused or concealed by the undesired events which are filtered out during the optical processing. Unwanted events are rejected by taking advantage of the differences between their dips (move out) and (or) frequencies and those of the desired reflections. Examples are discussed in which LaserScan techniques have been applied: Reject multiple reflections which override or obscure genuine reflections dipping in different directions. Remove diffractions and (or) reflected refractions. Attenuate high velocity noise events. Eliminate high frequency interference. LaserScan is very effective as a frequency filter because of the sharp cut-off slopes obtained. Because hundreds of information channels can be processed in a single photographic operation, optical filtering has proved to be an efficient and economical method of frequency and velocity filtering. End_of_Article - Last_Page 1087------------

INTERPRETATION OF THE TRANSIENT BEHAVIOR OF THE REFLECTION SEISMOGRAPH

This paper discusses a method of design for the reflection seismograph based on the galvanometer response when the geophone is subject to a unit impulse. A graphical method of obtaining the actual response to an arbitrary geophone motion in terms of the impulsive response is given. A family of desirable types of impulsive response is obtained by analyzing the implications of this graphical computation when strong low and high frequency interference is present. The application of this method of computation to the evaluation of corrections in the apparent arrival time of reflections obtained with different instruments is outlined.