Sine wave

About: Sine wave is a research topic. Over the lifetime, 12183 publications have been published within this topic receiving 93013 citations. The topic is also known as: sinusoid.

Sine wave beam web and method of manufacture

Abstract: The invention disclosed is (1) a sine wave web for structural elements made of composite materials, (2) structural combinations incorporating the web, and (3) a method of manufacturing the web. The concept disclosed avoids bunching and distortion of the fibers of the composite web material as it is shaped and flanged for attachment to adjacent structure, such as the chords and capstrips of an I-beam.

Transfer function analysis of the constant voltage anemometer

Abstract: The transfer function for the constant voltage anemometer (CVA) circuit has been derived in terms of circuit and hot-wire parameters and the expressions for the natural frequency and damping ratio have been obtained. Bandwidth in each case was determined from the plot of the normalized transfer function. The theoretical bandwidth behavior calculated from the transfer function plots for the prototype agrees with independent tests of the prototype using laser radiation heating of the hot wire in an air jet. The near constant value of the bandwidth of the CVA with the variation in the hot-wire overheat and its Reynolds number that were observed with the laser tests have been substantiated with the theoretical values from the transfer function. Bandwidth testing with sine wave injection, in situ time constant measurement for proper compensation setting, method to optimize the design to have nearly a constant bandwidth even with different compensation time constants and the operational advantages of CVA are also discussed.

Subscriber line impedance measurement device and method

Abstract: A device and method for line impendance measurement using a multi-frequency test signal (figure 1b, 1c) waveform in a signal injection technique featuring analysis of acquired line test response data. A multi-frequency test signal waveform (figure 1b, 1c) is injected into the subscriber line (figure 3), to obtain by data acquisition the line response in terms of voltage measurements, which are processed via a digital filter (14) to analyze a specific sine wave frequency. Using a multi-level rectangular wave signal as the test signal and analyzing at the dominant frequency derived from the rectangular signal, or other harmonics, it is possible to derive the line characteristics, including amplitude attenuation and phase shift, which constitute line impedance.

Newton algorithms for conditional and unconditional maximum likelihood estimation of the parameters of exponential signals in noise

Abstract: The authors present polynomial-based Newton algorithms for maximum likelihood estimation (MLE) of the parameters of multiple exponential signals in noise. This formulation can be used in the estimation, for example, of the directions of arrival of multiple noise-corrupted narrowband plane waves using uniform linear arrays and the frequencies of multiple noise-corrupted complex sine waves. The algorithms offer rapid convergence and exhibit the computation efficiency associated with the polynomial approach. Compact, closed-form expressions are presented for the gradients and Hessians. Various model assumptions concerning the statistics of the underlying signals are considered. Numerical simulations are presented to demonstrate the algorithms' performance. >

Techniques of Wind Vector Estimation from Data Measured with a Scanning Coherent Doppler Lidar

Abstract: The results of a theoretical study of the feasibility of wind velocity vector estimation from data, measured with a scanning coherent Doppler lidar, are presented. The estimation techniques considered are (a) the direct sine wave fitting (DSWF) and the filtered sine wave fitting (FSWF), where at first the radial wind velocities are estimated and then the wind vector is estimated from the dependence of the radial velocity versus the azimuth angle of the scanning; and (b) the maximum of the function of accumulated spectra (MFAS) and the maximum likelihood for the wind vector estimation (WV ML), where the wind vector is estimated directly from data measured by a scanning lidar without intermediate estimation of the radial wind velocities. It has been shown that due to strong averaging of noise fluctuations in accumulated spectra, the WV ML and MFAS techniques allow one to estimate the wind vector with acceptable accuracy at an essentially lower signal-to-noise ratio (SNR) than the methods of the sin...