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Magnetic components and static inverters and converters - sine current screening and sine flux screening core tests on test program materials
Four subroutines compute one-dimensional and multi-dimensional Fourier transforms for real data, multi-dimensional complex Fourier transforms, and multi-dimensional sine, cosine and sine-cosine transforms. Subroutines use Cooley-Tukey fast Fourier transform. In all but one-dimensional case, transforms are calculated in up to six dimensions.
The dose rate in a rotationally-symmetric radiation field near a space power reactor is assumed to be inversely proportional to separation distance squared and directly proportional either to a constant or a constant times the sine-cubed of a polar angle. Constant velocity motion is examined in both cases in both two and three dimensional geometries. The two dimensional geometry occurs when the line of motion and the field axis of symmetry are co-planar. The dose integral in the sine-cubed region may be integrated directly, but a more useful form is obtained after a change of variable. A coordinate system rotation greatly simplifies the results. The three dimensional problem is integrated after a change of variable. Finally, tables of normalized functions are presented and discussed.
An electromechanical device for generating both sine and cosine functions is described. A motor rotates a cylinder about an axis parallel to and a slight distance from the central axis of the cylinder. Two noncontacting displacement sensing devices are placed ninety degrees apart, equal distances from the axis of rotation of the cylinder and short distances above the surface of cylinder. Each of these sensing devices produces an electrical signal proportional to the distance that it is away from the cylinder. Consequently, as the cylinder is rotated the outputs from the two sensing devices are the sine and cosine functions.
The validity of approximating random Gaussian distributed inputs used in human response modeling by sums of discrete sine waves is studied. An ideal rectangular power density spectrum is simulated using both filtered Gaussian white noise and sums-of-discrete sine waves with three different input cutoff frequencies in the same compensatory tracking task. Resulting normalized tracking error and quality operator observations are used to investigate apparent discrepancies in human operator characteristics. Results show that discrete and continuous input tracking data compare favorable when the power in the crossover region is taken into account.
From a practical standpoint most dynamic response analysis techniques are complicated, expensive, and time consuming to mechanize and operate. Adaptive parameter tracking techniques partially overcome these faults, but they have prescribed forms which is an undesirable restriction for basic research. To overcome these drawbacks, an on-line Fourier analysis technique has been developed which deals only with the input and error signals in a manual feedback control system. Several sine waves are used for the input, and the on-line data measurement includes the error variance and a simple means for obtaining the sine and cosine transforms of the error signal at each of the input frequencies. From this relatively small amount of data, we show simple ways to compute the open- and closed-loop dynamic response at input frequencies and the relative amount of linearly correlated power in the error signal.
It is shown that for a class of finite first-order Markov signals, the Karhunen-Loeve (KL) transform for data compression is a set of periodic sine functions if the boundary values of the signal are fixed or known. These sine functions are shown to be related to the Fourier transform so that a fast Fourier transform algorithm can be used to implement the KL transform. Extension to two dimensions with reference to images with separable contravariance function is shown.
The effects of several characteristics of helicopter blade slap upon human annoyance are examined. Blade slap noise was simulated by using continuous and impulsive noises characterized by five parameters: The number of sine waves in a single impulse; the frequency of the sine waves; the impulse repetition frequency; the sound pressure level (SPL) of the continuous noise; and the idealized crest factor of the impulses. Ten second samples of noise were synthesized with each of the five parameters at representative levels. The annoyance of each noise was judged by 40 human subjects. Analysis of the subjective data indicated that each of the five parameters had a statistically significant effect upon the annoyance judgments. The impulse crest factor and SPL of the continuous noise had very strong positive relationships with annoyance. The other parameters had smaller, but still significant, effects upon the annoyance judgments.
The relative merits of quasi-square wave inverter-motor technology versus a sine wave inverter-motor system were investigated. The empirical results of several tests on various sizes of wye-wound induction motors are presented with mathematical analysis to support the conclusions of the study. It was concluded that, within the limitations presented, the quasi-square wave inverter-motor system is superior to the more complex sine wave system for most induction motor applications in space.
A tachometer in which sine and cosine signals responsive to the angular position of a shaft as it rotates are each multiplied by like, sine or cosine, functions of a carrier signal, the products summed, and the resulting frequency signal converted to fixed height, fixed width pulses of a like frequency. These pulses are then integrated, and the resulting dc output is an indication of shaft speed.
The Raman spectra of gaseous propane-d0 and -d3 have been recorded between 50 and 3500 cm. Considerable torsional data are reported and used to characterize the torsional potential function based on a semirigid model. The average 'effective' V3 for the propanes is found to be 1139 plus or minus 10/cm. The sine-sine coupling term is similar in magnitude but opposite in sign to the cosine-cosine coupling term in propane-d0.
Variable-frequency circuit develops sine square and triangular waveforms. Three-function generator used variable-rate integrator to generate triangular wave and zero-crossing detector to develop square wave. Sine wave generator uses diode matrix to operate on triangular wave, thus with design harmonic distortion in output is less then one percent. By changing values of outboard resistors and capacitors, same design can be used at higher frequencies.
The source of computational error in the inertial measurement unit (IMU) onorbit alignment software was investigated. Simulation runs were made on the IBM 360/70 computer with the IMU orbit alignment software coded in hal/s. The results indicate that for small IMU misalignment angles (less than 600 arc seconds), single precision computations in combination with the arc cosine method of eigen rotation angle extraction introduces an additional misalignment error of up to 230 arc seconds per axis. Use of the arc sine method, however, produced negligible misalignment error. As a result of this study, the arc sine method was recommended for use in the IMU onorbit alignment software.
The proposed modal test program differs from single-input methods in that preliminary data may be acquired using multiple inputs, and modal tuning procedures may be employed to define closely spaced frquency modes more accurately or to make use of frequency response functions (FRF's) which are based on several input locations. In some respects the proposed modal test proram resembles earlier sine-sweep and sine-dwell testing in that broadband FRF's are acquired using several input locations, and tuning is employed to refine the modal parameter estimates. The major tasks performed in the proposed modal test program are outlined. Data acquisition and FFT processing, curve fitting, and modal tuning phases are described and examples are given to illustrate and evaluate them.
It is shown that the use of a two-parameter limbshift and a meridional flow velocity fits solar velocity data better than the standard analysis defined by Howard et al. (1980). The data used are the coarse residual velocity arrays, with 34 equal intervals in both sine latitude and sine longitude. There are a total of 2899 full-disk observations between January 1, 1967, and December 12, 1980. The original velocity fields are reconstructed by adding into the residual arrays the large-scale patterns that were measured and removed on a daily basis by a standard reduction. Tests of this reconstituded data set show that no significant errors are introduced in the analysis of large-scale velocity fields. The results of the analysis presented here imply that the study of solar velocity pattern at the level of a few m/s requires that magnetic regions be treated separately from nonmagnetic regions.
Estimates of cloud street geometry produced by a model of the parallel/thermal instability modes of shallow convection are compared with observations obtained during the 1981 KonTur experiment. Good agreement between the modeled and observed orientation angles, wavelengths and Reynolds numbers are found when the streets are assumed to derive their energy from the average shear and the lowest order sine terms of a Fourier expansion of the mean wind profile (or equivalently from the lowest order cosine terms of the mean shear profile). The modes associated with the cosine terms of the wind profile (or the sine terms of the wind shear profile) do not agree well with the observations. These results suggest that the boundary layer rolls observed during KonTur might have developed owing to a combined parallel/thermal instability originating primarily from the cosine terms of the ambient roll parallel wind shear.
The noise generated by supersonic tip speed propellers may be a cabin environment problem for future propeller-driven airplanes. Active suppression from speakers inside the airplane cabin has been proposed for canceling out this noise. The potential of active suppression of advanced turboprop noise was tested by using speakers in a rectangular duct. Experiments were first performed with sine wave signals. The results compared well with the ideal cancellation curve of noise as a function of phase angle. Recorded noise signals from subsonic and supersonic tip speed propellers were than used in the duct to deterthe potential for canceling their noise. The subsonic propeller data showed significant cancellations but less than those obtained with the sine wave. The blade-passing-tone cancellation curve for the supersonic propeller was very similar to the subsonic curve, indicating that it is potentially just as easy to cancel supersonic as subsonic propeller blade-passing-tone noise. Propeller duct data from a recorded propeller source and spatial data taken on a propeller-drive airplane showed generally good agreement when compared versus phase angle. This agreement, combined with the similarity of the subsonic and supersonic duct propeller data, indicates that the area of cancellation for advanced supersonic propellers will be similar to that measured on the airplane. Since the area of cancellation on the airplane was small, a method for improving the active noise suppression by using outside speakers is discussed.
A system for the measurement of shaft angles is disclosed wherein a synchro resolver is sequentially pulsed, and alternately, a sine and then a cosine representative voltage output of it are sampled. Two like type, sine or cosine, succeeding outputs (V sub S1, V sub S2) are averaged and algebraically related to the opposite type output pulse (V sub c) occurring between the averaged pulses to provide a precise indication of the angle of a shaft coupled to the resolver at the instant of the occurrence of the intermediately occurring pulse (V sub c).