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7 results on '"Sinusoidal frequency"'

1. Numerical study of periodically heated wall effect on natural convection in an enclosure.

Author

Kumar, Anil and Rao, Pentyala Srinivasa

Subjects
*NATURAL heat convection, *FREE convection, *RAYLEIGH number, *NUSSELT number, *NUMERICAL solutions to equations, *FINITE difference method, *HEAT transfer
Abstract

The present numerical study focuses on sinusoidal heating and aspect ratio effects on heat flow of free convection of fluid inside the enclosure. The side walls are maintained at ambient temperature and the middle horizontal wall that divides the enclosure evenly is heated to sinusoidal temperature and the other horizontal walls are adiabatic. The numerical solution of the transport equations is done by the finite difference method to determine the heat transfer and thermal penetration with respect to aspect ratio, sinusoidal frequency and Rayleigh number. The numerical results of heat and fluid flow in the range of controlled governing parameters such as Rayleigh number (Ra = 105), sinusoidal frequency (1 ⩽ N ⩽ 4) and aspect ratio (0.2 ⩽ A ⩽ 4) are analysed in terms of streamlines, isotherms, heat penetration length and Nusselt number. It has been found that the 100% thermal penetration in the upper part of the enclosure of the aspect ratio A = 1 is obtained on continuous heating, while in the lower section, the maximum thermal penetration is limited to 98%, which is obtained on non-continuous heating in the enclosure of aspect ratio A = 0.2, 0.5. [ABSTRACT FROM AUTHOR]

Published
2023
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2. Discovery of a Unique Sinusoidal Frequency for the Effective Magnetic Treatment of Brackish Water.

Author

Dehghan, Tayebeh and Falamaki, Cavus

Subjects
WATER purification, BRACKISH waters, MAGNETIC fields
Abstract

Magnetic treatment of aqueous solutions containing dissolved CaCO3 is known to affect its precipitation exerted by heating or raising the pH of the solution. In this work, experiments have been performed on two kinds of water: (a) a simulated water containing only CaCO3 as dissolved salt and (b) a real brackish water sample of high total hardness from an industrial area containing a wide range of impurity salts. It has been discovered for the first time that using a sinusoidal magnetic field, treatment at a frequency of ca. 150 kHz (for a range of 0-1000 kHz) results in the maximum calcite precipitation independent of the initial water composition. The discovered phenomenon could be explained based on the resonance taking place due to the synchronization of the induced magnetic field with the proton exchange rate of water molecules. [ABSTRACT FROM AUTHOR]

Published
2018
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3. Influence of the Periodicity of Sinusoidal Boundary Condition on the Unsteady Mixed Convection within a Square Enclosure Using an Ag--Water Nanofluid.

Author

Karim, Azharul, Billah, M. Masum, Newton, M. T. Talukder, and Rahman, M. Mustafizur

Subjects
*NANOFLUIDS, *GRASHOF number, *HEAT transfer, *CONVECTIVE flow, *ATMOSPHERIC temperature
Abstract

A numerical study of the unsteady mixed convection heat transfer characteristics of an Ag--water nanofluid confined within a square shape lid-driven cavity has been carried out. The Galerkin weighted residual of the finite element method has been employed to investigate the effects of the periodicity of sinusoidal boundary condition for a wide range of Grashof numbers (Gr) (105 to 107) with the parametric variation of sinusoidal even and odd frequency, N, from 1 to 6 at different instants (for τ = 0.1 and 1). It has been observed that both the Grashof number and the sinusoidal even and odd frequency have a significant influence on the streamlines and isotherms inside the cavity. The heat transfer rate enhanced by 90% from the heated surface as the Grashof number (Gr) increased from 105 to 107 at sinusoidal frequency N = 1 and τ = 1. [ABSTRACT FROM AUTHOR]

Published
2017
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4. Influence of the Periodicity of Sinusoidal Boundary Condition on the Unsteady Mixed Convection within a Square Enclosure Using an Ag–Water Nanofluid

Author

Azharul Karim, M. Masum Billah, M. T. Talukder Newton, and M. Mustafizur Rahman

Subjects
Ag–water nanofluids, unsteady mixed convection, solid volume fraction, sinusoidal frequency, finite element method, Technology
Abstract

A numerical study of the unsteady mixed convection heat transfer characteristics of an Ag–water nanofluid confined within a square shape lid-driven cavity has been carried out. The Galerkin weighted residual of the finite element method has been employed to investigate the effects of the periodicity of sinusoidal boundary condition for a wide range of Grashof numbers (Gr) (105 to 107) with the parametric variation of sinusoidal even and odd frequency, N, from 1 to 6 at different instants (for τ = 0.1 and 1). It has been observed that both the Grashof number and the sinusoidal even and odd frequency have a significant influence on the streamlines and isotherms inside the cavity. The heat transfer rate enhanced by 90% from the heated surface as the Grashof number (Gr) increased from 105 to 107 at sinusoidal frequency N = 1 and τ = 1.

Published
2017
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5. Perceptual evaluation of modal synthesis for impact-based sounds

Author

Barahona, Adrián, Pauletto, Sandra, Barahona, Adrián, and Pauletto, Sandra

Abstract

The use of real-time sound synthesis for sound effects can improve the sound design of interactive experiences such as video games. However, synthesized sound effects can be often perceived as synthetic, which hampers their adoption. This paper aims to determine whether or not sounds synthesized using filter-based modal synthesis are perceptually comparable to sounds directly recorded. Sounds from 4 different materials that showed clear modes were recorded and synthesized using filter-based modal synthesis. Modes are the individual sinusoidal frequencies at which objects vibrate when excited. A listening test was conducted where participants were asked to identify, in isolation, whether a sample was recorded or synthesized. Results show that recorded and synthesized samples are indistinguishable from each other. The study outcome proves that, for the analysed materials, filter-based modal synthesis is a suitable technique to synthesize hit sound in real-time without perceptual compromises., QC 20200623

Published
2019

7. A novel full-wave rectifier/sinusoidal frequency doubler topology based on CFOAs

Author

Shahram Minaei, Muhammed A. Ibrahim, Erkan Yuce, Doğuş Üniversitesi, Mühendislik Fakültesi, Elektronik ve Haberleşme Mühendisliği Bölümü, TR46127, TR1566, and Minaei, Shahram

Subjects
Sinusoidal frequency, Engineering, Electric impedance, Hardware_PERFORMANCEANDRELIABILITY, 02 engineering and technology, NMOS transistors, Buffer circuits, Topology, law.invention, Matching condition, Frequency doubler, law, Full-wave rectifiers, 0202 electrical engineering, electronic engineering, information engineering, NMOS logic, Electronic circuit, Operational amplifiers, SPICE, Current-feedback operational amplifier, Low output and high input impedances, Electrical engineering, Electric rectifiers, Surfaces, Coatings and Films, Feedback amplifiers, Rectifying circuits, Hardware and Architecture, Frequency doublers, Metals, Operational amplifier, Electric network analysis, MOS devices, Frequency multiplier, Electric impedance measurement, Topology (electrical circuits), High input impedance, Transistors, Precision rectifier, Oxide semiconductors, CFOA, Rectifier, Grounded resistors, Hardware_INTEGRATEDCIRCUITS, Electronic engineering, business.industry, 020208 electrical & electronic engineering, Metal oxide semiconductor, 020206 networking & telecommunications, Full-wave rectifier, Signal Processing, business, Hardware_LOGICDESIGN
Abstract

A novel topology for realizing voltage-mode (VM) full-wave rectifier/sinusoidal frequency doubler based on current feedback operational amplifiers (CFOAs) and n-channel metal-oxide semiconductor (NMOS) transistors is proposed in this study. The proposed full-wave rectifier structure employs two CFOAs and three enhancement-mode NMOS transistors. With a slight modification, the sinusoidal frequency doubler circuit can be adopted from the full-wave rectifier circuit by replacing a grounded resistor instead of one of the NMOS transistors. Both of the proposed circuits enjoy low output and high input impedance properties which make them convenient for cascading easily with other VM circuits without needing any extra buffer circuits. No passive component matching conditions are needed. The proposed circuits are simulated by using SPICE program to verify the theoretical analysis. © 2017, Springer Science+Business Media, LLC.

Published
2017

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