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414 results on '"Nguyen, Truong Khang"'

125. 2DEG characteristics of InAlAs/InP based HEMTs by solving Schrödinger and Poisson equations followed by device characteristics.

Author

Lenka, Trupti Ranjan, Singh, Rajan, Tripathy, Susanta Kumar, Goyal, Vishal, Nguyen, Truong Khang, and Nguyen, Hieu Pham Trung

Subjects
POISSON'S equation, MODULATION-doped field-effect transistors, FREQUENCIES of oscillating systems, ELECTRON gas, ENERGY bands, CONDUCTION bands
Abstract

In this paper the 2DEG characteristics study of InAlAs/InP based high electron mobility transistor (HEMT) structures with two different channel materials (InAlAs and InGaAs) are presented through self‐consistent solutions of Schrodinger and Poisson equations which results in energy bands, sheet charge density, electric field, sheet resistance and CV charactristics. The 2DEG (two dimensional electron gas) is created at the heterointerface of InAlAs/In(Al,Ga)As due to conduction energy band discontinuity. The 2DEG is realised by the presence of subbands at the quantum well. The subbands represent the wave function of electrons. The innovation of this work is that InAlAs and InGaAs with x = 0.75 composition can be best utilised as channel material due to low bandgaps 0.821 and 0.639 eV respectively towards improved 2DEG density, subbands, channel sheet resistance, electric field in the 2DEG and CV characteristics. The DC characteristics comprised of Id ~ Vg, Id ~ Vd, transconductance, cut‐off frequency, maximum frequency of oscillation are extracted through TCAD simulations followed by experimental validation. The InGaAs/InP based HEMT can be a potential candidate for ultra‐high‐speed microwave and millimetre wave applications. [ABSTRACT FROM AUTHOR]

Published
2022
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126. Design and analysis of on‐demand reconfigurable WiMAX/WLAN high isolation 2 × 2 MIMO antenna oriented adjacent/orthogonally for imaging applications in UWB‐X band.

Author

Sharma, Manish, Kumar, Rajeev, Kaur, Preet, Dhasarathan, Vigneswaran, and Nguyen, Truong Khang

Subjects
ULTRA-wideband antennas, PIN diodes, ANTENNAS (Electronics), IEEE 802.16 (Standard)
Abstract

In this reported work, two dual notched bands from 3.39 GHz to 3.92 GHz and from 4.43 GHz to 5.48 GHz for the WiMAX band (3.3–3.8 GHz) and for (lower) WLAN band (5.15–5.35 GHz) MIMO antenna with adjacent/orthogonal orientations has been investigated. Also, the proposed antenna is capable of controlling these notched bands whenever the need for power saving arises by reconfiguring them using PIN diodes. The issue of isolation between the radiating elements has been overcome by placing the radiating structures in the adjacent and orthogonal arrangement. The proposed antenna is characterized proving an average gain of 4.15/4.37 dBi and maximum radiation efficiency of 91/87% for adjacent/orthogonal orientation. The proposed antenna also shows good agreement with simulated and measured impedance bandwidth, diversity performances in terms of ECC, DG, TARC, and CCL for which values are well below the permissible range. [ABSTRACT FROM AUTHOR]

Published
2022
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127. Application of nano-refrigerant for boiling heat transfer enhancement employing an experimental study

Author

Sheikholeslami, M, Rezaeianjouybari, Behnoush, Darzi, Milad, Shafee, Ahmad, Li, Zhixiong, Nguyen, Truong Khang, Sheikholeslami, M, Rezaeianjouybari, Behnoush, Darzi, Milad, Shafee, Ahmad, Li, Zhixiong, and Nguyen, Truong Khang

Abstract

This research presents the outputs for nano-refrigerant (R600a/oil/CuO) boiling heat transfer within flattened channels utilizing experimental method. The influence of flattened percentage, flow rate, vapor quality as well as the mass fraction of CuO on boiling heat transfer (h) were discussed. Outcomes reveal that increasing the flattened percentage enhances the h. Also, within the ranges of present experiment, h augments by increasing nanoparticle's concentration.

Published
2019

128. Measurement of refractive index and viscosity for aqueous solution of sodium acetate, sodium carbonate, trisodium citrate, (glycerol + sodium acetate), (glycerol + sodium carbonate), and (glycerol + trisodium citrate) at T = 293.15 to 303.15 K and atmospheric pressure

Author

Mehdi Bagheri, Farhoush Kiani, Nguyen Truong Khang, Fardad Koohyar, and Fatemeh Zabihi

Subjects
Aqueous solution, Analytical chemistry, 02 engineering and technology, Activation energy, 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Mole fraction, 01 natural sciences, Atomic and Molecular Physics, and Optics, 0104 chemical sciences, Electronic, Optical and Magnetic Materials, chemistry.chemical_compound, Viscosity, chemistry, Materials Chemistry, Physical and Theoretical Chemistry, 0210 nano-technology, Sodium carbonate, Ternary operation, Sodium acetate, Spectroscopy, Trisodium citrate
Abstract

The Refractive index and viscosity are important physico-chemical properties of solutions that have many applications in research and industrial works. In this study, we measured the refractive index and viscosity for binary solutions of (water + sodium acetate), (water + sodium carbonate), and (water + trisodium citrate), as well as ternary solutions of (water + sodium acetate + glycerol), (water + sodium carbonate + glycerol), and (water + trisodium citrate + glycerol) in a wide range of mole fractions of solutes at T = (293.15, 298.15 and 303.15) K and atmospheric pressure. These measurements were done in order to study on the interactions between solute and solvent species in our studied solutions at different temperatures. For binary mixtures, the measured refractive indices were correlated with a linear equation. The values of constants of this linear equation, Kr,s, can help us to better understand the power of interaction between solute and solvent species in binary solutions of this study. Also, for ternary solutions of this study, the values of refractive index were calculated using a multiple equation that was suggested by Koohyar in 2018. Jones-Dole equation and Kumar equation were used for fitting viscosities of all solutions at different temperatures. In addition, the values of change of refractive index on mixing, ΔnD, and activation energy for viscous flow, Ea(vis), were calculated using refractive index and viscosity data, respectively. For binary solutions of this study the values of ΔnD were fitted by Redlich-Kister polynomial equation. For ternary solutions of this study the values of ΔnD were fitted by Singe et al., Calvo et al., and also, Nagata and Sakura equations.

Published
2020

129. A Very Wideband Circularly Polarized Crossed Straight Dipole Antenna with Cavity Reflector and Single Parasitic Element

Author

Cong Danh Bui, Huy Hung Tran, Minh Thuan Doan, and Nguyen Truong Khang

Subjects
Pulmonary and Respiratory Medicine, Physics, business.industry, Bandwidth (signal processing), Axial ratio bandwidth, law.invention, Dipole, Optics, law, Pediatrics, Perinatology and Child Health, Parasitic element, Dipole antenna, Wideband, business, Circular polarization, Broadside
Abstract

A very wideband circularly polarized (CP) crossed dipole antenna is presented in this paper. The primary radiating element of the antenna consists of two straight dipoles arranged orthogonally through double printed rings. To further enhance the axial ratio bandwidth, a cavity with proper size and single parasitic element are employed to generate two additional bands. The use of cavity reflector is investigated thoroughly, providing a solid framework for designing this type of antennas. The final design with an overall size of 0.92λo × 0.92λo × 0.32λo at the center CP frequency yields a measured –10 dB-impedance bandwidth of 75.2% and 3 dB-axial ratio bandwidth of 67.7%. The proposed antenna exhibits right-handed circular polarization and an average broadside gain of about 8.3 dBi over the CP operating bandwidth.

Published
2018

146. Optimal design of circular baffles on sloshing in a rectangular tank horizontally coupled by structure

Author

Jamalabadi, Mohammad Yaghoub Abdollahzadeh (author), Ho-Huu, V. (author), Nguyen, Truong Khang (author), Jamalabadi, Mohammad Yaghoub Abdollahzadeh (author), Ho-Huu, V. (author), and Nguyen, Truong Khang (author)

Abstract

Parametric studies on the optimization of baffles on vibration suppression of partially filled tanks coupled by structure have been widely conducted in literature. However, few studies focus on the effect of the position of the baffles on fluid flow stratification and dampening the motion. In the present study, a numerical investigation, an engineering analysis, and optimal design study were performed to determine the effect of external flow on circular obstacle baffles performance on suppressing the vibrations of coupled structure in a closed basin. The single degree of freedom model (mass-spring-damper) is used to model the structure that holds the tank. The coupled system is released from an initial displacement without a velocity. The governing mass, turbulent Navier-Stokes momentum, volume of fluid, and one degree of freedom structure equations are solved by the Pressure-Implicit with Splitting of Operators algorithm in fluids and Newmark method in structure. Based on a detailed study of transient structure motion coupled with sloshing dynamics, the optimal baffle location was achieved. Optimal position of the baffle and its width are systematically obtained with reference to the quiescent free surface., Air Transport & Operations

Published
2018
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147. Nanoparticles for water desalination in solar heat exchanger.

Author

Seyednezhad, Mohadeseh, Sheikholeslami, M., Ali, Jagar A., Shafee, Ahmad, and Nguyen, Truong Khang

Subjects
SOLAR stills, SALINE water conversion, SOLAR heating, NANOFLUIDS, HEAT exchangers, RENEWABLE energy sources, WATER purification
Abstract

Producing potable water is a critical issue due to the lack of access to clean H2O and the increasing demands of environment. One of the main technologies for water purification is solar still using the sustainable and green source of energy. To augment the efficiency of solar unit, nanoparticles are combined with the saline water. Nanofluids are suspended materials that besides the different geometries (single slope, double slope, tubular...) of the solar stills have a significant impact on improvement of the thermal conductivity of the brackish H2O. Further, combining nanomaterial with solar energy system appears to be more cost-effective approach for potable water production since they boost the evaporation and condensation rate. This paper is a comprehensive literature on different types of nanofluid and various numerical, experimental and analytical methods that researchers have applied to augment the efficiency of system. [ABSTRACT FROM AUTHOR]

Published
2020
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148. Investigation of convective nanomaterial flow and exergy drop considering CVFEM within a porous tank.

Author

Alrobaian, Abdulrahman A., Alsagri, Ali Sulaiman, Ali, Jagar A., Hamad, Samir Mustafa, Shafee, Ahmad, Nguyen, Truong Khang, and Li, Zhixiong

Subjects
CONVECTIVE flow, PERMEABILITY, INVESTIGATIONS, EXERGY, TANKS, BUOYANCY
Abstract

In the current research, ferrofluid migration and exergy destroyed became the main goal. Demonstration of characteristics impact of permeability, buoyancy and Hartmann numbers on variation of nanomaterial movement as well as irreversibility was examined. CVFEM with triangular element is utilized to calculate the solution of formulated equations. An increment in magnetic field results in greater exergy drop which is not beneficial in view of convective mode. An increase in permeability demonstrates a growth of nanomaterial convective flow. Augmenting Da causes a reduction in Bejan number while it makes Nuave to augment. [ABSTRACT FROM AUTHOR]

Published
2020
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149. Effectiveness of various shapes of Al2O3 nanoparticles on the MHD convective heat transportation in porous medium: CVFEM modelling.

Author

Vo, Dat D., Hedayat, Mohammadali, Ambreen, Tehmina, Shehzad, Sabir A., Sheikholeslami, M., Shafee, Ahmad, and Nguyen, Truong Khang

Subjects
POROUS materials, RAYLEIGH number, MAGNETISM, HEAT transfer, NANOFLUIDS, NANOPARTICLES
Abstract

The influences of Al2O3 nanoparticles with various shapes on thermal characteristics of nanofluid within a permeable space concerning magnetic force have been simulated by means of CVFEM. To form the final PDEs, radiation term has been incorporated. Impacts of magnetic force, radiation constraint, Rayleigh number and shape factor on nanomaterial behaviour have been analysed. Results demonstrate that the higher values of shape factor lead to augmented convective heat transfer. By augmenting the magnetic strength, conductive heat transfer can be predominant than that of the convection. [ABSTRACT FROM AUTHOR]

Published
2020
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150. Design of heat exchanger with combined turbulator.

Author

Nguyen, Truong Khang, Sheikholeslami, M., Jafaryar, M., Shafee, Ahmad, Li, Zhixiong, Chandra Mouli, Kotturu V. V., and Tlili, I.

Subjects
*HEAT exchangers, *NANOFLUIDS, *HEAT transfer, *TURBULENT flow
Abstract

In this article, influence of inserting new turbulator on resistance and heat transfer behaviors of a pipe has been analyzed. This kind of turbulator can be utilized for retrofit applications. Turbulent nanofluid flow is imposed. Homogenous approach for nanofluid and k–ɛ approach for turbulent modeling were involved. Contours are presented for different inlet velocity and pitch ratio. Results indicated that the lower the pitch ratio, the better is the temperature gradient. Nanofluid transfers more heat with decline of pitch ratio because of lower generation of longitudinal disturbance. As inlet velocity augments and pitch ratio decreases, nanofluid can scour the wall more easily and heat transfer rate is strengthened. [ABSTRACT FROM AUTHOR]

Published
2020
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