NEW HYBRID TECHNIQUE FOR SOLVING THREE DIMENSIONAL TELEGRAPH EQUATIONS

2021 ◽  
Vol 24 (2) ◽  
pp. 153-165
Author(s):  
Gurpreet Singh ◽  
Inderdeep Singh
Keyword(s):  
Three Dimensional ◽  
Hybrid Technique ◽  
Telegraph Equations

Numerical study of multi-dimensional hyperbolic telegraph equations arising in nuclear material science via an efficient local meshless method

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Imtiaz Ahmad ◽  
Aly R. Seadawy ◽  
Hijaz Ahmad ◽  
Phatiphat Thounthong ◽  
Fuzhang Wang
Keyword(s):  
Meshless Method ◽  
Material Science ◽  
Numerical Study ◽  
Research Work ◽  
Time Integration ◽  
Three Dimensional ◽  
Nuclear Material ◽  
Telegraph Equations ◽  
Model Equations ◽  
Derivatives Of

Abstract This research work is to study the numerical solution of three-dimensional second-order hyperbolic telegraph equations using an efficient local meshless method based on radial basis function (RBF). The model equations are used in nuclear material science and in the modeling of vibrations of structures. The explicit time integration technique is utilized to semi-discretize the model in the time direction whereas the space derivatives of the model are discretized by the proposed local meshless procedure based on multiquadric RBF. Numerical experiments are performed with the proposed numerical scheme for rectangular and non-rectangular computational domains. The proposed method solutions are converging quickly in comparison with the different existing numerical methods in the recent literature.

scholarly journals Lifting restrictions on coherence loss when characterizing non-transparent hypersonic phononic crystals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Konrad Rolle ◽  
Dmytro Yaremkevich ◽  
Alexey V. Scherbakov ◽  
Manfred Bayer ◽  
George Fytas
Keyword(s):  
Frequency Domain ◽  
Hybrid Approach ◽  
Three Dimensional ◽  
Phononic Crystals ◽  
Hybrid Technique ◽  
Detection Mechanism ◽  
Pump Probe ◽  
Fabry Perot ◽  
Multilayer Stacks ◽  
Deposition Techniques

AbstractHypersonic phononic bandgap structures confine acoustic vibrations whose wavelength is commensurate with that of light, and have been studied using either time- or frequency-domain optical spectroscopy. Pulsed pump-probe lasers are the preferred instruments for characterizing periodic multilayer stacks from common vacuum deposition techniques, but the detection mechanism requires the injected sound wave to maintain coherence during propagation. Beyond acoustic Bragg mirrors, frequency-domain studies using a tandem Fabry–Perot interferometer (TFPI) find dispersions of two- and three-dimensional phononic crystals (PnCs) even for highly disordered samples, but with the caveat that PnCs must be transparent. Here, we demonstrate a hybrid technique for overcoming the limitations that time- and frequency-domain approaches exhibit separately. Accordingly, we inject coherent phonons into a non-transparent PnC using a pulsed laser and acquire the acoustic transmission spectrum on a TFPI, where pumped appear alongside spontaneously excited (i.e. incoherent) phonons. Choosing a metallic Bragg mirror for illustration, we determine the bandgap and compare with conventional time-domain spectroscopy, finding resolution of the hybrid approach to match that of a state-of-the-art asynchronous optical sampling setup. Thus, the hybrid pump–probe technique retains key performance features of the established one and going forward will likely be preferred for disordered samples.

scholarly journals Bimodal Porous Scaffolds by Sequential Electrospinning of Poly(glycolic acid) with Sucrose Particles

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
B. Wulkersdorfer ◽  
K. K. Kao ◽  
V. G. Agopian ◽  
A. Ahn ◽  
J. C. Dunn ◽  
...  
Keyword(s):  
Glycolic Acid ◽  
Three Dimensional ◽  
Porous Scaffolds ◽  
Hybrid Technique ◽  
Electrospun Scaffolds ◽  
Limited Application ◽  
Novel Method ◽  
Particulate Leaching ◽  
The One ◽  
Laminated Structures

Electrospinning is a method to produce fine, biopolymer mesh with a three-dimensional architecture that mimics native extra-cellular matrix. Due to the small fiber diameter created in this process, conventional electrospun scaffolds have pore sizes smaller than the diameter of most cells. These scaffolds have limited application in tissue engineering due to poor cell penetration. We developed a hybrid electrospinning/particulate leaching technique to create scaffolds with increased porosity and improved cellular ingrowth. Poly(glycolic acid) (PGA) and a sucrose-ethanol suspension were electrospun in equal, alternating sequences at intervals of one, two, and ten minutes each. The scaffolds revealed fiber mesh with micropores of 10 m and uniformly distributed sucrose particles. Particulate leaching of sucrose from the one- or two-minute scaffolds revealed honeycomb structures with interconnected macropores between 50 and 250 m. Sucrose leaching from the ten-minute scaffolds resulted in laminated structures with isolated macropores between 200 and 350 m. Macropore size was directly proportional to the duration of the sucrose spinning interval. After 24 hours of cell culture, conventionally spun scaffolds demonstrated no cellular penetration. Conversely, the PGA/sucrose scaffolds demonstrated deep cellular penetration. This hybrid technique represents a novel method of generating electrospun scaffolds with interconnected pores suitable for cellular ingrowth.

An Efficient Finite Element Procedure for the Analysis of Cross-Flow Micro Heat Exchangers

2010 ◽  
Author(s):  
C. Nonino ◽  
S. Savino ◽  
S. Del Giudice
Keyword(s):  
Heat Exchangers ◽  
Three Dimensional ◽  
Cross Flow ◽  
Computational Effort ◽  
Velocity Fields ◽  
Hybrid Technique ◽  
Number Of Layers ◽  
Micro Heat Exchanger ◽  
Finite Element Procedure ◽  
Transfer Problems

As an alternative to massive CFD, a hybrid technique, which has the advantage of accounting for all of the three-dimensional features of the flow field, but with a limited computational effort, is used for the solution of conjugate convection-conduction heat transfer problems in cross-flow micro heat exchangers. The key feature of the proposed method is represented by the separate computation of the velocity fields in single microchannels and on the subsequent mapping of such velocity fields onto the three-dimensional grid used to solve the thermal problem. The cross-flow micro heat exchangers considered in the paper consist of a number of layers of rectangular microchannels. A parametric study is carried out on the combined effect on cross-flow micro heat exchanger thermal performances due to the variation of the microchannel cross-section and of the ratio of solid to fluid thermal conductivity.

Comparative Study Regarding Two Obturation Methods with Thermoplasticized Gutta-Percha for the Root Canals

2016 ◽  
Vol 695 ◽  
pp. 12-19
Author(s):  
Mihaela Jana Ţuculină ◽  
Lelia Gheorghiţă ◽  
Oana Andreea Diaconu ◽  
Marilena Bătăiosu ◽  
Ionela Teodora Dascălu ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Comparative Study ◽  
Methyl Salicylate ◽  
Three Dimensional ◽  
The Other ◽  
Hybrid Technique ◽  
Root Canals ◽  
Gutta Percha ◽  
Definite Improvement

AIM: This study draws a comparison, through the transparentization method, focusing on the quality of the canal obturation made with thermoplasticized gutta-percha, between two different systems: GuttaMaster VDW (München, Germany), based on obturators made of a plastic core, covered in alpha gutta-percha, and a system of vertical warm condensation.MATERIALS AND METHODS: The study focused on twenty teeth extracted for various reasons which underwent the endodontic treatment realized through a hybrid technique, using the rotary files system of NiTi MTWO (VDW, München, Germany), and the manual files k-file type (Kendo, VDW, München, Germany). The teeth were distributed into two groups of ten. The teeth in the first group underwent obturation using the CWC technique of vertical warm obturation, and the teeth in the second group underwent root obturation using the GuttaMaster system (VDW, München, Germany). The teeth were decalcified in nitric acid. Using the method of transparentization with methyl salicylate, there were emphasized aspects regarding the abilities of each method to seal three-dimensionally the endodontic space.RESULTS: The teeth which underwent vertical obturation presented many more holes in the obturation material, holes situated mainly in the medial and coronary third. However, these teeth presented the highest degree of insertion in the lateral canals, as compared to the other obturation technique employed. The homogeneity of the root obturation had not had any statistical significant differences between the two techniques. However, the technique of injecting thermoplasticized gutta-percha was superior to the other one regarding the tightness on the edge and the degree of penetration in the lateral canals.CONCLUSIONS: The knowledge of both the qualities and the limits of the obturation material chosen, as well as the correctness of performing the two techniques, determines a definite improvement of the quality of the canal treatment, which ends with a three-dimensional canal obturation.

An Overview of Methods and a New Three-Dimensional FEA and Analytical Hybrid Technique for Calculating AC Winding Losses in PM Machines

2021 ◽  
Vol 57 (1) ◽  
pp. 352-362
Author(s):  
Narges Taran ◽  
Dan M. Ionel ◽  
Vandana Rallabandi ◽  
Greg Heins ◽  
Dean Patterson
Keyword(s):  
Three Dimensional ◽  
Hybrid Technique

scholarly journals Label Fusion Strategy Selection

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Nicolas Robitaille ◽  
Simon Duchesne
Keyword(s):  
Medical Image ◽  
Three Dimensional ◽  
Simulated Data ◽  
Real Data ◽  
Medical Image Segmentation ◽  
Hybrid Technique ◽  
Strategy Selection ◽  
Label Fusion ◽  
Input Element ◽  
Almost All

Label fusion is used in medical image segmentation to combine several different labels of the same entity into a single discrete label, potentially more accurate, with respect to the exact, sought segmentation, than the best input element. Using simulated data, we compared three existing label fusion techniques—STAPLE, Voting, and Shape-Based Averaging (SBA)—and observed that none could be considered superior depending on the dissimilarity between the input elements. We thus developed an empirical, hybrid technique called SVS, which selects the most appropriate technique to apply based on this dissimilarity. We evaluated the label fusion strategies on two- and three-dimensional simulated data and showed that SVS is superior to any of the three existing methods examined. On real data, we used SVS to perform fusions of 10 segmentations of the hippocampus and amygdala in 78 subjects from the ICBM dataset. SVS selected SBA in almost all cases, which was the most appropriate method overall.

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