scholarly journals Novel Design of Electromagnetic Bandgap Using Fractal Geometry

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Huynh Nguyen Bao Phuong ◽  
Dao Ngoc Chien ◽  
Tran Minh Tuan
Keyword(s):  
Band Structure ◽  
Structural Design ◽  
Fractal Geometry ◽  
Experimental Results ◽  
Dual Band ◽  
Electromagnetic Bandgap ◽  
Unit Cells ◽  
Simulation Results ◽  
Novel Design ◽  
Good Agreement

A novel electromagnetic bandgap (EBG) structural design based on Fractal geometry is presented in this paper. These Fractals, which are the Sierpinski triangles, are arranged to repeat each 60° to produce the hexagonal unit cells. By changing the gap between two adjacent Sierpinski triangles inside EBG unit cell, we can produce two EBG structures separately that have broadband and dual bandgap. By using the suspending microtrip method, two arrays 3 × 4 of EBG unit cells are utilized to investigate the bandgap of the EBG structures. The EBG operation bandwidth of the broadband structure is about 87% and of the dual-band structure is about 40% and 35% at the center bandgap frequencies, respectively. Moreover, a comparison between the broadband EBG and the conventional mushroom-like EBG has been done. Experimental results of the proposed design show good agreement in comparison with simulation results.

scholarly journals Flexible Design of EGB Structure for Antenna Appliations

2013 ◽  
Author(s):  
Huynh Nguyen Bao Phuong
Keyword(s):  
Patch Antenna ◽  
Ground Plane ◽  
Dual Band ◽  
Flexible Design ◽  
Electromagnetic Bandgap ◽  
High Impedance ◽  
Radiation Properties ◽  
Unit Cells ◽  
Simulation Results ◽  
Good Agreement

In  this paper,  we  present  a  flexible  design of  electromagnetic  bandgap  (EBG)  structure,  which  is constructed  based  on  Fractal  geometry,  for  antenna applications.  These  Fractals,  which  are  the  Sierpinski triangles,  are  arranged  to  repeat  each 600to  introduce the  hexagonal  unit  cells.  By  changing  the  gap  between two adjacent Sierpinski triangles inside EBG unit cell, it can  be  introducing  two  EBG  structuresseparately  that have  broadband  and  dual  bandgap.  By  using  the suspending  microstrip  method, two arrays 3×4  of  EBG unit  cells  areutilized  to  investigate  the  bandgap  of  the EBG  structures.  The  EBG  operation  bandwidth  of  the broadband  structure  and  the  dual-band  structure  are about  87%  and  40%;  35%  at  the  center  bandgap frequencies,  respectively.  Moreover,  a  comparison between  the  broadband  EBG  and  the  conventional mushroom-like  EBG  has  been  done.  Experimental results  of  the  proposed  design  show  good  agreement  in comparison  with  simulation  results.  Finally,  the proposed  EBG  structures  are  studied  as  a  high impedance  ground  plane  for  enhancing  the  radiation properties of a patch antenna.

scholarly journals Numerical Simulations of V-Shaped Plates Subjected to Blast Loadings: A Validation Study

2016 ◽  
Vol 10 (11) ◽  
pp. 203
Author(s):  
Mohd Zaid Othman ◽  
Qasim H. Shah ◽  
Muhammad Akram Muhammad Khan ◽  
Tan Kean Sheng ◽  
M. A. Yahaya ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Variable Mass ◽  
Blast Loading ◽  
Experimental Results ◽  
Average Difference ◽  
Simulation Results ◽  
Blast Loadings ◽  
Carrier Vehicle ◽  
Good Agreement

A series of numerical simulations utilizing LS-DYNA was performed to determine the mid-point deformations of V-shaped plates due to blast loading. The numerical simulation results were then compared with experimental results from published literature. The V-shaped plate is made of DOMEX 700 and is used underneath an armour personal carrier vehicle as an anti-tank mine to mitigate the effects of explosion from landmines in a battlefield. The performed numerical simulations of blast loading of V-shaped plates consisted of various angles i.e. 60°, 90°, 120°, 150° and 180°; variable mass of explosives located at the central mid-point of the V-shaped vertex with various stand-off distances. It could be seen that the numerical simulations produced good agreement with the experimental results where the average difference was about 26.6%.

Stick-Slip Vibration Between Two Large Concentric Circular Discs in Rotational Contact With Multiple Point Loads

2003 ◽  
Author(s):  
M. Baleri ◽  
F. Sassani ◽  
P. L. Ko
Keyword(s):  
Experimental Results ◽  
Integral Model ◽  
Mathematical Representation ◽  
Multiple Point ◽  
Stick Slip ◽  
System Parameters ◽  
Modeling Simulation ◽  
Contact Loads ◽  
Simulation Results ◽  
Good Agreement

This paper presents a study of the stick-slip frictional phenomenon when large contact areas subjected to uneven contact loads are involved. The objective of the investigation is to gain better understanding of the phenomenon from experimental observations and to develop a mathematical representation that can be used for modeling, simulation and design purposes. A dynamic integral-model has been proposed and simulations have been carried out. The effects of various system parameters on the behavior of the system have been studied experimentally and analytically. The simulation results using the proposed integral-model are in good agreement with the experimental results. The latter also show that stick-slip vibrations can be influenced by the loading conditions.

NH4+ Ion Motions in Some Ammonium Salts

1981 ◽  
Vol 36 (3) ◽  
pp. 205-209 ◽  
Author(s):  
Fevzi Köksal
Keyword(s):  
Hydrogen Bonding ◽  
Low Temperatures ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Experimental Results ◽  
Ammonium Salts ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Unit Cells ◽  
Good Agreement

Spin-lattice relaxation times of protons in polycrystalline (NH4)2SO4, (NH3OH)2SO4, (NH4)2HPO4, NH4VO3, (NH4)2CrO4, (NH4)2C2O4 • H2O and NH4HF2 salts were measured over the temperature range 100-430 K. The double minima in T1 for the first three compounds were attributed to the nonequivalent NH4+ ions in the unit cells. In NH4VO3, the double minima were attributed to the reorientations about two and three fold axes. However only one minimum in T1 was observed for (NH4)2CrO4, (NH4)2C2O4 • H2O and NH4HF2 and the relaxation mechanisms for the first three compounds were attributed to random reorientations of NH4+ ions. The experimental results are in good agreement with the calculated values by using the existing theoretical expressions. The discrepancies between experimental and calculated values for (NH4)2HPO4 and NH4HF2 at low temperatures were attributed to the tightness of the hydrogen bonding at those temperatures

Quintuple band circular monopole antenna with innovative 3-D printed PLA substrate for wireless applications

Frequenz ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ashraf E. Ahmed ◽  
Wael A.E. Ali ◽  
Sudipta Das
Keyword(s):  
Polylactic Acid ◽  
Monopole Antenna ◽  
Design Concept ◽  
Experimental Results ◽  
Printed Antenna ◽  
Wireless Applications ◽  
Innovative Technique ◽  
Compact Size ◽  
Simulation Results ◽  
Good Agreement

Abstract In this paper, a circular antenna with a 3-D printed substrate is introduced to achieve a multiband behavior. The circular antenna is matched using a key-shaped stub located on the perimeter of the designed antenna. The 3-DP circular antenna adopted the apollonian gasket technique to perform the multi-circular cuttings in the Polylactic Acid (PLA) substrate as an innovative technique to obtain quintuple bands. The proposed antenna is designed to operate for Bluetooth, WLAN, WiMAX, and other wireless applications in S-band and C-band. The designed antenna has a compact size of 61.1 × 43.6 × 1 mm3. The prototype of the suggested 3-D printed antenna is fabricated and measured to confirm the simulation results. A good agreement is evident between simulation and experimental results which validates the design concept.

Bond-Slip Numerical Simulation of Concrete and Gypsum Board

2011 ◽  
Vol 255-260 ◽  
pp. 3133-3136
Author(s):  
Quan Bin Zhao ◽  
Xin Liang Jiang
Keyword(s):  
Numerical Simulation ◽  
Constitutive Relation ◽  
Simulation Analysis ◽  
Experimental Results ◽  
Gypsum Board ◽  
Bond Slip ◽  
Pull Out ◽  
Simulation Results ◽  
Research Situation ◽  
Good Agreement

The characteristics and research situation of bond-slip performance at the inter face of concrete and other materials are introduced, and the bond-slip constitutive relation models are summarized at the same time. Through the load-slip curves obtained from the pull-out experiment of CFFP, the proposed bond-slip constitutive relation models are presenting, including the simple one. With the numerical simulation analysis of CFFP is carried out by the use of the proposed constitutive relation, while the numerical simulation results are in good agreement with the experimental results conducted before, which is feasible and can be applied to further research on CFFP.

Heat Transfer Investigation of an Additively Manufactured Minichannel Heat Exchanger

2019 ◽  
Author(s):  
Hamidreza Rastan ◽  
Amir Abdi ◽  
Monika Ignatowicz ◽  
Bejan Hamawandi ◽  
Poh Seng Lee ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Single Phase ◽  
Three Dimensional ◽  
Heat Fluxes ◽  
Experimental Results ◽  
Working Fluid ◽  
Minichannel Heat Exchanger ◽  
Simulation Results ◽  
Good Agreement

Abstract This study investigates the thermal performance of laminar single-phase flow in an additively manufactured minichannel heat exchanger both experimentally and numerically. Distilled water was employed as the working fluid, and the minichannel heat exchanger was made from aluminum alloy (AlSi10Mg) through direct metal laser sintering (DMLS). The minichannel was designed with a hydraulic diameter of 2.86 mm. The Reynolds number ranged from 175 to 1360, and the heat exchanger was tested under two different heat fluxes of 1.5 kWm−2 and 3 kWm−2. A detailed experiment was conducted to obtain the thermal properties of AlSi10Mg. Furthermore, the heat transfer characteristics of the minichannel heat exchanger was analyzed numerically by solving a three-dimensional conjugate heat transfer using the COMSOL Multiphysics® to verify the experimental results. The experimental results were also compared to widely accepted correlations in literature. It is found that 95% and 79% of the experimental data are within ±10% range of both the simulation results and the values from the existing correlations, respectively. Hence, the good agreement found between the experimental and simulation results highlights the possibility of the DMLS technique as a promising method for manufacturing future multiport minichannel heat exchangers.

scholarly journals Compact Dual-Band Dual-Polarized Antenna for MIMO LTE Applications

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Lila Mouffok ◽  
Anne Claire Lepage ◽  
Julien Sarrazin ◽  
Xavier Begaud
Keyword(s):  
Free Space ◽  
Experimental Results ◽  
Dual Band ◽  
Antenna Diversity ◽  
Mobile Terminals ◽  
Central Wavelength ◽  
Lower Band ◽  
Dual Polarized ◽  
Dual Polarized Antenna ◽  
Good Agreement

A system of two dual-band dual-polarized antennas is proposed. It operates in two bands, 700 to 862 MHz and 2.5 to 2.69 GHz, thereby making it suitable for LTE applications. The design is composed of two compact orthogonal monopoles printed close to each other to perform diversity in mobile terminals such as tablets or laptops. For each band, two orthogonal polarizations are available and an isolation higher than 15 dB is achieved between the two monopoles spaced byλ0/10 (whereλ0the central wavelength in free space of the lower band). A good agreement is observed between simulated and experimental results. The antenna diversity capability is highlighted with the calculation of envelope correlation and mean effective gain for several antennas' positions in different environment scenarios.

Nanoindentation on a Ni Nanodot-Patterned Surface

2008 ◽  
Author(s):  
Hengyu Wang ◽  
Min Zou ◽  
Robert L. Jackson ◽  
Preston R. Larson ◽  
Matthew B. Johnson
Keyword(s):  
Finite Element ◽  
Numerical Simulations ◽  
Experimental Results ◽  
Spherical Contact ◽  
Patterned Surface ◽  
Size And Shape ◽  
Ordered Arrays ◽  
Simulation Results ◽  
Good Agreement

Nanoindentation on a Ni nanodot-patterned surface (NDPS) was investigated experimentally and numerically. The Ni NDPS consists of well-ordered arrays of Ni nanodots with approximately the same size and shape. The nanoindentation experiments were performed on the Ni NDPS using diamond tips of 1 and 5 μm radii of curvature. To efficiently simulate large number of nanodots in contact, numerical simulations were carried out using formulae empirically fitted from a finite element (FE) study of a single spherical contact. The simulation results were found to be in good agreement with the experimental results.

Compact dual-band bandpass filter using open stub-loaded stepped impedance resonator with cross-slots

2016 ◽  
Vol 9 (2) ◽  
pp. 269-274 ◽  
Author(s):  
Bukuru Denis ◽  
Kaijun Song ◽  
Fan Zhang
Keyword(s):  
Bandpass Filter ◽  
Design Concept ◽  
Dual Band ◽  
High Isolation ◽  
Transmission Zeros ◽  
Full Wave ◽  
Measurement Results ◽  
Stepped Impedance Resonator ◽  
Simulation Results ◽  
Good Agreement

A compact dual-band bandpass filter using stub-loaded stepped impedance resonator (SLSIR) with cross-slots is presented. The symmetric SLSIR is analyzed using even- and odd-mode techniques. Design equations are derived and they are used to guide the design of the circuits. Two passbands can be easily tuned by cross-slots and open stubs. Transmission zeros among each passbands are created, resulting in high isolation and frequency selectivity. An experimental circuit is fabricated and evaluated to validate the design concept. The fabricated filter is compact with 19.76 × 12.7 mm2. The measurement results are in good agreement with the full-wave simulation results.

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