Three-dimensional few-cycle optical pulses of Gaussian and super-Gaussian cross-section inside the Bragg medium based on carbon nanotubes with dissipation

2019 ◽  
Vol 33 (23) ◽  
pp. 1950275
Author(s):  
Y. V. Dvuzhilova ◽  
I. S. Dvuzhilov ◽  
A. V. Ten ◽  
E. V. Boroznina ◽  
M. B. Belonenko
Keyword(s):  
Carbon Nanotubes ◽  
Cross Section ◽  
Cross Sections ◽  
Pulse Propagation ◽  
Three Dimensional ◽  
Optical Pulses ◽  
Additional Energy ◽  
Special Aspect ◽  
Dynamic Propagation ◽  
Energy Pumping

We have considered the problem of dynamic propagation of the three-dimensional few-cycle optical pulses of Gaussian and super-Gaussian cross-section inside the Bragg medium with carbon nanotubes. The system has dissipation and additional energy “pumping”. We have shown that the pulse propagation is stable inside the considered environment. The special aspect of the pulse evolution of different cross-sections has been determined.

scholarly journals Световые пули с бесселевым поперечным сечением в среде углеродных нанотрубок

2022 ◽  
Vol 130 (3) ◽  
pp. 407
Author(s):  
А.М. Белоненко ◽  
И.С. Двужилов ◽  
Ю.В. Двужилова ◽  
М.Б. Белоненко
Keyword(s):  
Carbon Nanotubes ◽  
Key Words ◽  
Cross Section ◽  
Nonlinear Medium ◽  
Three Dimensional ◽  
Optical Pulses ◽  
Limited Region ◽  
Conservation Of Energy ◽  
Light Bullets ◽  
Extremely Short Optical Pulses

The propagation of three-dimensional extremely short optical pulses (light bullets) with a Bessel cross section in a medium of carbon nanotubes placed in an optical resonator is considered. As a result of numerical calculations, it was found that such pulses propagate stably with conservation of energy in a limited region of space, including at large times of the order of 100 ps. Key words: extremely short optical pulses, nonlinear medium, light bullets, carbon nanotubes.

scholarly journals Световые пули в периодически неоднородной среде ориентированных углеродных нанотрубок в оптическом резонаторе

2019 ◽  
Vol 126 (4) ◽  
pp. 477
Author(s):  
М.Б. Белоненко ◽  
И.С. Двужилов ◽  
Ю.В. Двужилова ◽  
С.В. Борознин
Keyword(s):  
Carbon Nanotubes ◽  
Inhomogeneous Medium ◽  
Pulse Shape ◽  
Pulse Propagation ◽  
Optical Cavity ◽  
Three Dimensional ◽  
Propagation Rate ◽  
Optical Pulses ◽  
Varying Parameters ◽  
Propagation Dynamics

AbstractThe problem of the propagation dynamics of three-dimensional ultimately short optical pulses in an optical cavity in a periodically inhomogeneous medium of oriented carbon nanotubes is considered. It is shown numerically that such pulses demonstrate stable and sustainable propagation. In addition, it is shown that one can control for the pulse propagation rate and modify the pulse shape by varying parameters of the inhomogeneous medium.

Three-dimensional diffraction-free Airy pulses in the medium of carbon nanotubes under the conditions of an optical resonator

2021 ◽  
pp. 110-115
Author(s):  
A.M. Belonenko ◽  
◽  
Yu.V. Dvuzhilova ◽  
I.S. Dvuzhilov ◽  
M.B. Belonenko ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Cross Section ◽  
Short Pulse ◽  
Three Dimensional ◽  
Pulse Velocity ◽  
Optical Resonator ◽  
Optical Pulses ◽  
Pulse Dynamics ◽  
Semiconductor Carbon Nanotubes ◽  
Extremely Short Optical Pulses

Theoretically investigated the propagation of three-dimensional extremely short optical pulses, the longitudinal Airy cross section in a medium of semiconductor carbon nanotubes under the conditions of an optical resonator. Using numerical simulations, it was found that carbon nanotubes placed in an optical resonator create an environment in which the pulse propagates stably and conserves its energy, and also makes it possible to control some properties of an extremely short pulse (velocity and shape). The calculations of the pulse dynamics were carried out at long times, on the order of 100 ps.

scholarly journals Dynamic modeling of tunnel survey spatiotemporal data

2014 ◽  
Vol 20 (2) ◽  
pp. 354-375
Author(s):  
Xiaolong Li ◽  
Jiansi Yang ◽  
Bingxuan Guo ◽  
Hua Liu ◽  
Jun Hua
Keyword(s):  
Survey Data ◽  
Cross Section ◽  
Cross Sections ◽  
3D Modeling ◽  
3D Model ◽  
Three Dimensional ◽  
Spatiotemporal Data ◽  
Excavation Process ◽  
Special Cases ◽  
Time Stamps

Currently, for tunnels, the design centerline and design cross-section with time stamps are used for dynamic three-dimensional (3D) modeling. However, this approach cannot correctly reflect some qualities of tunneling or some special cases, such as landslips. Therefore, a dynamic 3D model of a tunnel based on spatiotemporal data from survey cross-sections is proposed in this paper. This model can not only playback the excavation process but also reflect qualities of a project typically missed. In this paper, a new conceptual model for dynamic 3D modeling of tunneling survey data is introduced. Some specific solutions are proposed using key corresponding technologies for coordinate transformation of cross-sections from linear engineering coordinates to global projection coordinates, data structure of files and database, and dynamic 3D modeling. A 3D tunnel TIN model was proposed using the optimized minimum direction angle algorithm. The last section implements the construction of a survey data collection, acquisition, and dynamic simulation system, which verifies the feasibility and practicality of this modeling method.

scholarly journals Membrane analogy for multi-material bars under torsion

2019 ◽  
Vol 475 (2225) ◽  
pp. 20190124 ◽  
Author(s):  
Laura Galuppi ◽  
Gianni Royer-Carfagni
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Cross Sections ◽  
Three Dimensional ◽  
Element Model ◽  
Elastic Problem ◽  
Two Dimensional ◽  
Torsion Problem ◽  
Linear Elastic ◽  
Physical Apparatus

Prandtl's membrane analogy for the torsion problem of prismatic homogeneous bars is extended to multi-material cross sections. The linear elastic problem is governed by the same equations describing the deformation of an inflated membrane, differently tensioned in regions that correspond to the domains hosting different materials in the bar cross section, in a way proportional to the inverse of the material shear modulus. Multi-connected cross sections correspond to materials with vanishing stiffness inside the holes, implying infinite tension in the corresponding portions of the membrane. To define the interface constrains that allow to apply such a state of prestress to the membrane, a physical apparatus is proposed, which can be numerically modelled with a two-dimensional mesh implementable in commercial finite-element model codes. This approach presents noteworthy advantages with respect to the three-dimensional modelling of the twisted bar.

scholarly journals Computational Study of Zigzag Spacer Design with Elliptical Cross-Section Filaments

2020 ◽  
Vol 307 ◽  
pp. 01047
Author(s):  
Gohar Shoukat ◽  
Farhan Ellahi ◽  
Muhammad Sajid ◽  
Emad Uddin
Keyword(s):  
Mass Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Computational Study ◽  
Flow Direction ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Two Dimensional ◽  
Permeate Flux ◽  
Elliptical Cross

The large energy consumption of membrane desalination process has encouraged researchers to explore different spacer designs using Computational Fluid Dynamics (CFD) for maximizing permeate per unit of energy consumed. In previous studies of zigzag spacer designs, the filaments are modeled as circular cross sections in a two-dimensional geometry under the assumption that the flow is oriented normal to the filaments. In this work, we consider the 45° orientation of the flow towards the three-dimensional zigzag spacer unit, which projects the circular cross section of the filament as elliptical in a simplified two-dimensional domain. OpenFOAM was used to simulate the mass transfer enhancement in a reverse-osmosis desalination unit employing spiral wound membranes lined with zigzag spacer filaments. Properties that impact the concentration polarization and hence permeate flux were analyzed in the domain with elliptical filaments as well as a domain with circular filaments to draw suitable comparisons. The range of variation in characteristic parameters across the domain between the two different configurations is determined. It was concluded that ignoring the elliptical projection of circular filaments to the flow direction, can introduce significant margin of error in the estimation of mass transfer coefficient.

Adapting the Simple Through Girder to Sit in Nature, The Wupperthal Footbridge

2021 ◽  
Author(s):  
John Anderson ◽  
Warrick de Kock
Keyword(s):  
South Africa ◽  
Finite Element ◽  
Cross Section ◽  
Cross Sections ◽  
Three Dimensional ◽  
Cad Model ◽  
Tourist Destination ◽  
Box Section ◽  
The Town ◽  
Elegant Form

<p>Some places are hard to get to and Wupperthal, a small town nestled deep within in the Cederberg Mountains, in South Africa is one of those places. Founded by German missionaries in 1830 the town is home to 1400 inhabitants and a growing tourist destination. An adjacent river, however, is a barrier during the wet seasons for farm children trying to reach the town’s school. A permanent footbridge was therefore recently commissioned to replace temporary structures that have proved dangerous. This paper tells the story of the single span through girder footbridge. Designed to sit as a comfortable object in its natural surroundings the new footbridge is both functional and attractive. The tapering steel plated cross section presents a profiled elevation that splits to create an arched opening at the midspan of the bridge. To create this elegant form the design had to prevent the buckling of the unbraced top chord of the girder. This was achieved through an iterative study of various cross sections and the transitioning of the plate girder into a box section over the opening. Developing a three-dimensional CAD model of the bridge helped engineers conceive the slender form. The model was then exported to create the finite element plated model and then developed into full workshop drawings. The bridge is considered simple but striking in its appearance and this paper aims to highlight that standard solutions can be transformed where appropriate within limited means.</p>

scholarly journals Two-dimensional few cycle optical pulses inside a carbon nanotubes photonic crystal

2019 ◽  
Vol 220 ◽  
pp. 03010
Author(s):  
Yulia V. Dvuzhilova ◽  
Ilya S. Dvuzhilov ◽  
Mikhail B. Belonenko
Keyword(s):  
Carbon Nanotubes ◽  
Photonic Crystal ◽  
Pulse Propagation ◽  
Two Dimensional ◽  
Optical Pulses

We have considered the problem of evolution of the two-dimensional few cycle optical pulses (FCOP) inside a photonic crystal made of carbon nanotubes. It has been shown that pulse propagation is stable inside the considered environment and it is possible to control and to change the velocity of the pulse propagation by photonic crystal parameters changing.

scholarly journals Effects of Bridge-Shaped Microchannel Geometry on the Performance of a Micro Laminar Flow Fuel Cell

Micromachines ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 822
Author(s):  
Muhammad Tanveer ◽  
Kwang-Yong Kim
Keyword(s):  
Fuel Cell ◽  
Numerical Model ◽  
Laminar Flow ◽  
Cross Section ◽  
Cross Sections ◽  
Three Dimensional ◽  
Narrow Channel ◽  
Navier Stokes ◽  
Cross Sectional ◽  
Square Channel

A laminar flow micro fuel cell comprising of bridge-shaped microchannel is investigated to find out the effects of the cross-section shape of the microchannel on the performance. A parametric study is performed by varying the heights and widths of the channel and bridge shape. Nine different microchannel cross-section shapes are evaluated to find effective microchannel cross-sections by combining three bridge shapes with three channel shapes. A three-dimensional fully coupled numerical model is used to calculate the fuel cell’s performance. Navier-Stokes, convection and diffusion, and Butler-Volmer equations are implemented using the numerical model. A narrow channel with a wide bridge shape shows the best performance among the tested nine cross-sectional shapes, which is increased by about 78% compared to the square channel with the square bridge shape.

Statistics of low-density microcellular materials

1994 ◽  
Vol 9 (2) ◽  
pp. 515-522 ◽  
Author(s):  
David A. Noever
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Material Properties ◽  
Three Dimensional ◽  
Low Density ◽  
Topological Relations ◽  
Packing Effects

The statistics of random cellular patterns are analyzed in cross sections of low-density microcellular materials. Agreement is found with a variety of topological relations previously found for other networks, namely Lewis's law and Aboav's law. To investigate three-dimensional packing effects, experiments are performed on compressed polystyrene shot material, the resulting networks of which are subsequently analyzed in cross section. Implications for material properties and stability are discussed.

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