Selection Of Optimum Frequency Research Articles

Loss minimization based optimal frequency selection for low frequency transmission lines using telegrapher’s method

PurposeThe purpose of this study is to obtain the optimal frequency for low-frequency transmission lines while minimizing losses and maintaining the voltage stability of low-frequency systems. This study also emphasizes a reduction in calculations based on mathematical approaches.Design/methodology/approachTelegrapher’s method has been used to reduce large calculations in low-frequency high-voltage alternating current (LF-HVac) lines. The static compensator (STATCOM) has been used to maintain voltage stability. For optimal frequency selection, a modified Jaya algorithm (MJAYA) for optimal load flow analysis was implemented.FindingsThe MJAYA algorithm performed better than other conventional algorithms and determined the optimum frequency selection while minimizing losses. Voltage stability was also achieved with the proposed optimal load flow (OLF), and statistical analysis showed that the proposed OLF reduces the frequency deviation and standard error of the LF-HVac lines.Originality/valueThe optimal frequency for LF-HVac lines has been achieved, Telegrapher’s method has been used in OLF, and STATCOM has been used in LF-HVac transmission lines.

Statistical electromagnetics for industrial pharmaceutical lyophilization.

Lyophilization is a common unit operation in pharmaceutical manufacturing but is a prolonged vacuum drying process with poor energy utilization. Microwave-assisted vacuum drying has been investigated to accelerate the lyophilization process. However, the literature lacks methodical approaches that consider the lyophilizer, the lyophilizate, the microwave power uniformity, the resulting heat uniformity, and the scalability. We present a microwave-vacuum drying method based on the statistical electromagnetics theory. The method offers an optimum frequency selection procedure that accounts for the lyophilizer and the lyophilizate. The 2.45GHz frequency conventionally utilized is proven to be far from optimum. The method is applied in a microwave-assisted heating configuration to pharmaceutical excipients (sucrose and mannitol) and different myoglobin formulations in a lab-scale lyophilizer. At 18GHz frequency and 60W microwave power, the method shows nearly three times speed-up in the primary drying stage of sucrose relative to the conventional lyophilization cycle for typical laboratory batches. The uniformity of the microwave power inside the chamber is controlled within ± 1 dB. The resulting heating uniformity measured through residual moisture analysis shows 12.7% of normalized SD of moisture level across the batch in a microwave-assisted cycle as opposed to 15.3% in the conventional cycle. Conventional and microwave lyophilized formulations are characterized using solid-state hydrogen-deuterium exchange-mass spectrometry (ssHDX-MS), solid-state Fourier transform infrared spectroscopy (ssFTIR), circular dichroism (CD), and accelerated stability testing (AST). Characterization shows comparable protein structure and stability. Heat and mass transfer simulations quantify further effects of optimal volumetric heating via the high-frequency statistical microwave heating.

Performance analysis of forced convection coolers using synthetic jets with variations in altitude from synthetic jets to heat sources

Every electronic device has a disadvantage that is heat generated from the components contained in the device while operating. The heat that occurs during the process can affect the effectiveness of these electronic devices. The cooling fan is directed to a heat source from an electronic device with the aim of maintaining the device’s performance temperature. However, the cooling fan used still has some disadvantages in terms of dimensions. Therefore, research on synthetic jets is carried out as an innovation in cooling. This study aims to find wave characteristics as a source. Optimum frequency selection to support cooling. As well as the ideal height of synthetic jets to heat sources. The method used in the research is direct and computer-based data retrieval for CFD. The use of triangular waves as a source of cooling with a frequency of 80 Hz at an altitude of 8 cm can reduce rapidly. However, the lowest final temperature comes from a height of 2 cm which is 28.1 °C.

Selection of Optimum Frequency for Sonar Echoes From Under Water Targets

Method is given for selecting optimum frequency for detection of echoes from targets using underwater sound. Attenuation of sound in water increases with frequency while diffraction spreading of the echo decreases. The frequency has also to be chosen so that the estimated strength of the echo is above the observed reverberation level.

Optimum frequency selection in multifrequency interferometry.

We describe a novel technique for measurement of absolute order of interference in multifrequency interferometry. An optimization criterion is introduced that leads to frequency selection formulations that are optimized with respect to the minimum number of frequencies required for achieving the maximum target dynamic range. The method is generalized to N frequencies and gives a definition of measurement reliability. We demonstrate the technique by means of coherent fringe projection for nonintrusive, full-field profilometry. Experimental data for three frequencies are presented.

Selection of optimum frequency of a wind scatterometer

The problem of selecting the optimum operating frequency of a scatterometer, used for remote sensing of sea surface wind speed has been addressed by applying the criteria of maximum sensitivity of backscattering coefficient to wind speed as well as its correlation with wind speed. The backscattering coefficient values for sea surface were computed by the two-scale scattering theory. To compute the atmospheric transmittance, 753 clear sky atmospheres over Indian Ocean were used. While the correlation coefficient was uniform (0.94) throughout the frequency range of 1 to 30GHz, only frequencies above 5GHz were found sensitive enough to yield a wind speed accuracy of ±2msec−1 and better, the accuracy improving with frequency.

Selection of optimum frequency of a wind scatterometer

Selection of optimum frequency of a wind scatterometer

Selection of optimum frequencies for atmospheric electric path length measurement by satellite-borne microwave radiometers

Numerical experiments using regressions by leaps and hounds have been performed to determine the optimum frequencies for satellite-borne microwave radiometers to estimate atmospheric electrical path length over the sea. The frequency range 5-40 GHz was searched. The effect of surface wind speed, sea surface temperature, and clouds was considered in the optimum frequency selection. Our analysis indicates that \sim 0.6 -cm rms accuracy is possible for one-way path length measurement using a proper pair of frequencies. The best two-channel subset selected by the leaps and bounds technique is [16.0, 21.0] GHz.

A note on optimum frequency and damping for optically recording strong motion accelerographs

Selection of optimum frequency and damping for single degree of freedom acceleration transducer with optical or mechanical magnification is investigated. It is shown that for (1) empirical characterization of Fourier Amplitude spectrum of strong earthquake motion in the United States, (2) digitization noise associated with automatic digitization employing rotating drum scanner, and (3) recording sensitivities on film in the range from 1 cm/g to 4 cm/g, the optimum transducer frequency should be between 45 Hz and 50 Hz and the optimum damping should be between 55% and 60%.