scholarly journals Lightning Protection of Ancient Chola Monument in South India Based on Three-Dimensional Geometric and Electro-Geometric Techniques

2020 ◽  
Vol 9 (3) ◽  
pp. 988-994
Keyword(s):  
South India ◽  
Three Dimensional ◽  
Detailed Comparison ◽  
Lightning Protection ◽  
Shielding Effectiveness ◽  
Shielding Failure ◽  
Common Framework ◽  
Critical Zones ◽  
Geometric Techniques ◽  
Angle Method

Lightning is one of the most commonly occurring natural phenomena which causes irrecoverable damage toedifices which include monuments that uniquely showcase global heritage. Most monuments are usually built tall since these signify symbols of victory, whereby invariably becoming vulnerable to lightning. Though several researchers have implemented various Lightning Protection Systems (LPS) to a considerable level of success, substantial statistical variations in prospective stroke currents during lightning due to factors such as climate change,complexities in geographical topography etc., present considerable challenges in obtaining a common framework for protection of structures. Hence, this research focuses on carrying out analysis based on exhaustive case-studies for an ancient United Nations Educational, Scientific and Cultural Organization (UNESCO) monument in South India. The first objective of this research is in carrying out detailed comparison of shielding effectiveness based on 3D geometric and electro-geometric LPS strategies such as Protection Angle Method (PAM) and Rolling Sphere Method (RSM). The second aims at assessment of risk in accordance with IEC 62305 for estimation of level of risk and the role of varying lightning protection levels utilizing striking distance models to obtain the appropriate choice of the location of air terminal. The third focuses on conducting cross-validation studies to assess the adequacy of the proposed location of LPS using SESShield-3D by depicting the critical zones that necessitate additional protection. In addition, shielding failure analysis of the proposed LPS is also carried out. Inferences on unshielded zones for the three-dimensional (3D) layout models of the monuments have been summarized with appropriate recommendations.

scholarly journals Compressive behaviours of octet-truss lattices

2020 ◽  
Vol 234 (16) ◽  
pp. 3257-3269 ◽  
Author(s):  
Yifan Li ◽  
Huaiyuan Gu ◽  
Martyn Pavier ◽  
Harry Coules
Keyword(s):  
Failure Modes ◽  
Density Ratio ◽  
Three Dimensional ◽  
Compressive Load ◽  
High Strength ◽  
Detailed Comparison ◽  
Compressive Response ◽  
Beam Elements ◽  
Structural Applications ◽  
Octet Truss

Octet-truss lattice structures can be used for lightweight structural applications due to their high strength-to-density ratio. In this research, octet-truss lattice specimens were fabricated by stereolithography additive manufacturing with a photopolymer resin. The mechanical properties of this structure have been examined in three orthogonal orientations under the compressive load. Detailed comparison and description were carried out on deformation mechanisms and failure modes in different lattice orientations. Finite element models using both beam elements and three-dimensional solid elements were used to simulate the compressive response of this structure. Both the load reaction and collapse modes obtained in simulations were compared with test results. Our results indicate that three-dimensional continuum element models are required to accurately capture the behaviour of real trusses, taking into account the effects of finite-sized beams and joints.

scholarly journals In-Depth Verification of a Numerical Model for an Axisymmetric RC Dome

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2152
Author(s):  
Przemysław Czumaj ◽  
Sławomir Dudziak ◽  
Zbigniew Kacprzyk
Keyword(s):  
Three Dimensional ◽  
Spatial Models ◽  
Detailed Comparison ◽  
The Finite Element Method ◽  
Robot System ◽  
Engineering Structures ◽  
Computational Analyses ◽  
Computational Systems ◽  
Good Agreement ◽  
Made In

The designers of civil engineering structures often have to face the problem of the reliability of complex computational analyses performed most often with the Finite Element Method (FEM). Any assessment of reliability of such analyses is difficult and can only be approximate. The present paper puts forward a new method of verification and validation of the structural analyses upon an illustrative example of a dome strengthened by circumferential ribs along the upper and lower edges. Four computational systems were used, namely Abaqus, Autodesk Robot, Dlubal RFEM, and FEAS. Different models were also analyzed—two-dimensional (2D) and three-dimensional (3D) ones using continuum, bar, and shell finite elements. The results of the static (with two kinds of load—self-weight and load distributed along the upper ring) and modal analyses are presented. A detailed comparison between the systems’ and models’ predictions was made. In general, the spatial models predicted a less stiff behavior of the analyzed dome than the planar models. The good agreement between different models and systems was obtained for the first natural frequency with axisymmetric eigenmodes (except from the Autodesk Robot system). The presented approach to the verification of complex shell–bar models can be effectively applied by structural designers.

scholarly journals The circulation of the Persian Gulf: a numerical study

2005 ◽  
Vol 2 (3) ◽  
pp. 129-164 ◽  
Author(s):  
J. Kämpf ◽  
M. Sadrinasab
Keyword(s):  
United Arab Emirates ◽  
Persian Gulf ◽  
Thermal Stratification ◽  
Numerical Study ◽  
Three Dimensional ◽  
Detailed Comparison ◽  
Mass Properties ◽  
Inverse Estuary ◽  
The Persian Gulf ◽  
Autumn And Winter

Abstract. We employ a three-dimensional hydrodynamic model (COHERENS) to study the circulation and water mass properties of the Persian Gulf, which is a large inverse estuary. Our findings suggest that the Persian Gulf experiences a distinct seasonal cycle in which a Gulf-wide cyclonic overturning circulation establishes in spring and summer, but this disintegrates into mesoscale eddies in autumn and winter. Establishment of the Gulf-wide circulation coincides with establishment of thermal stratification and strengthening of the baroclinic exchange circulation through the Strait of Hormuz. The latter is associated with winter cooling of extreme saline (>45 psu) water in shallow regions along the coast of United Arab Emirates. To validate the model results, we present a detailed comparison with observational evidence.

scholarly journals Spatial Orientation of Galaxies in Supercluster S[195+027+0022]

2019 ◽  
Vol 5 (1) ◽  
pp. 14-18
Author(s):  
J. R. Malla ◽  
B. Aryal ◽  
W. Saurer
Keyword(s):  
Galaxy Formation ◽  
Spatial Orientation ◽  
Three Dimensional ◽  
Position Angle ◽  
Sloan Digital Sky Survey ◽  
Spin Vector ◽  
Sky Survey ◽  
Hierarchy Model ◽  
Vector Orientation ◽  
Angle Method

We present a study of spin vector orientation of 1198 SDSS (Sloan Digital Sky Survey) galaxies in Super cluster S[195+027+0022] having red shift 0.07 to 0.09. The databases of these galaxies are taken from SDSS (Sloan Digital Sky Survey) 7th and 9th data release. We have converted two dimensional data to three-dimensional by Godlowskian Transformation using position angle-inclination angle method. We intend to find non-random effects in the spatial orientation of galaxies in Super cluster. No preferred alignment of angular momentum vectors (spin vector) is noticed, supporting Hierarchy model of galaxy formation.

scholarly journals A detailed comparison between the endoscopic images using blue laser imaging and three-dimensional reconstructed pathological images of colonic lesions

PLoS ONE ◽  
2020 ◽  
Vol 15 (6) ◽  
pp. e0235279
Author(s):  
Takeshi Ueda ◽  
Kohei Morita ◽  
Fumikazu Koyama ◽  
Yuichi Teramura ◽  
Tadashi Nakagawa ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Detailed Comparison ◽  
Blue Laser ◽  
Laser Imaging ◽  
Endoscopic Images ◽  
Blue Laser Imaging

scholarly journals Analysis of Arc Processes in Multi-chamber Arrester for Lightning Protection at High-voltage Overhead Power Lines

2017 ◽  
Vol 4 (2) ◽  
pp. 124-128 ◽  
Author(s):  
Iu. V. Murashov ◽  
V. Ya. Frolov ◽  
D. Uhrlandt ◽  
S. Gortschakow ◽  
D. V. Ivanov ◽  
...  
Keyword(s):  
Discharge Chamber ◽  
Three Dimensional ◽  
Plasma Temperature ◽  
Power Lines ◽  
Lightning Protection ◽  
Computational Domain ◽  
Transient Model ◽  
Electromagnetic Processes ◽  
Model Equations ◽  
Overhead Power Lines

Nowadays multi-chamber arresters are widely distributed as devices of lightning protection of overhead power lines. A mathematical modelling of processes in the discharge chamber of multichamber arrester is necessary to carry out in order to improve its breaking capacity. A three-dimensional mathematical transient model of thermal, gas-dynamic and electromagnetic processes taking place in the discharge chamber of multi-chamber arrester is presented in the article. Basic assumptions, model equations, a computational domain and the boundary conditions are described. Plasma turbulence is taken into account. The results of the calculation i.e. distributions of plasma temperature and overpressure in the discharge chamber at different time points are shown. The analysis of the results was carried out. It is shown that the presence of cavities in the electrodes design promotes electric arc extinction in the discharge chamber of multi-chamber arrester.

The effects of the structural parameters of three-dimensional warp interlock woven fabrics with silver-based hybrid yarns on electromagnetic shielding behavior

2019 ◽  
Vol 90 (11-12) ◽  
pp. 1354-1371
Author(s):  
Marzieh Javadi Toghchi ◽  
Carmen Loghin ◽  
Irina Cristian ◽  
Christine Campagne ◽  
Pascal Bruniaux ◽  
...  
Keyword(s):  
Unit Area ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Woven Fabrics ◽  
Electromagnetic Shielding ◽  
Woven Fabric ◽  
Shielding Effectiveness ◽  
Conductive Material ◽  
Conductive Yarns ◽  
Multifilament Yarns

The main objective of the present study was to investigate the increase in the electromagnetic shielding effectiveness (EMSE) of a set of five variants of three-dimensional (3D) warp interlock woven fabrics containing silver multifilament yarns arranged in a 3D orthogonal grid. The EMSE enlargement as a factor of increasing the quantity of the conductive material per unit area was investigated. The quantity of the conductive material per unit area in a 3D woven fabric can be enlarged by increasing either the yarn undulation or the number of conductive yarn systems, while the yarn density and yarn fineness are fixed. Thus, the binding depth of the conductive warp was gradually increased for the first four variants in order to increase the yarn undulation. Alternatively, the conductive weft system was doubled for the last variant with the aim of increasing the quantity of the conductive component. It should be noted that changing the weave structure requires less effort and energy while keeping the same threading of warps in the reed compared to altering the warp density. The EMSE was measured in an anechoic chamber and the shielding was satisfactory for all the variants in the frequency range of 1–6 GHz (19–44 dB). The results revealed that increasing only 7% of the waviness degree of the conductive warps led to 17% EMSE improvement due to increasing of the conductive yarns through the thickness of the variants. Moreover, no upward EMSE was detected for the last variant, despite the fact that the conductive weft system was doubled.

Electromagnetic shielding performance of three-dimensional woven fabrics with copper-based hybrid yarn in X-band frequency range

2018 ◽  
Vol 49 (4) ◽  
pp. 484-502 ◽  
Author(s):  
Dharmendra Nath Pandey ◽  
Arindam Basu ◽  
Pramod Kumar ◽  
Himangshu B Baskey
Keyword(s):  
Cotton Fabric ◽  
Three Dimensional ◽  
Electromagnetic Shielding ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Structural Configuration ◽  
Band Frequency ◽  
Hybrid Yarn ◽  
X Band ◽  
Electromagnetic Shielding Effectiveness

This study involves a comprehensive evaluation of electromagnetic shielding characteristics of multilayer three-dimensional conductive fabrics by using cotton/copper wrapped hybrid yarn in X band frequency range. Five, three-dimensional fabrics with different structural configuration, such as orthogonal, angle interlock, cellular spacer, multi-tubular spacer, and contour were produced. Three different series of all five structures was also developed using pure cotton fabric, conductive hybrid yarn in weft and one-third hybrid yarn and two-third cotton yarn in warp Also, the effect of vertical and horizontal polarization of electromagnetic waves on electromagnetic shielding effectiveness was studied. The comparative analysis of reflectance transmittance and absorption behavior was also undertaken. The results indicate that pure cotton fabric (A series) does not have electromagnetic shielding capabilities. The difference between the electromagnetic shielding effectiveness values in vertical and horizontal planes of fabrics, having conductive hybrid yarn in weft direction (B series), showed significantly better results on the vertical plane in comparison to that on the horizontal plane. Fabric containing conductive hybrid yarn in both warp and weft (C series) exhibits consistent electromagnetic shielding effectiveness in both the planes. It is worth mentioning that the structural configuration in all five three-dimensional fabrics in B and C series has shown differential trends of electromagnetic shielding effectiveness in terms of reflectance, transmittance and absorption behavior. They are also found to be statistically significant. Finally, it is concluded that the conductive 3-D multilayer system develops special protective capabilities, mostly due to its larger surface area.

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