Heat conductivity of three-dimensional regular structures of crystalline and amorphous selenium incorporated in voids of synthetic opal

Two structures of metallic thermal protection system(TPS) for hypersonic vehicle were presented. One model was a multi-layer construction and the other has cavities in the metallic layer. Numerical simulations were conducted on the three-dimensional TPS models using CFD software of Gambit and Fluent. Two heating temperatures of 1073K and 773K with constant temperature and isothermal boundary conditions were considered. Heat transfer was treated as single conductivity and thermal radiation effect was not involved. The results of simulation investigation showed that: The metallic layer had poor capability to restrict the heat conductivity. Heat was easier to transfer across the bracket into the internal part of the TPS. The ability of cavities in metallic layer to resist heat conductivity was limited. The temperature-heating time variation pattern was similar for different external heating temperature. Internal cooling was important for the TPS. The thermal radiation effect on the TPS would be focused in further research.

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Global Existence of the Three Dimensional Heat-conductive Incompressible Viscous Fluids

MATEC Web of Conferences ◽

10.1051/matecconf/201817901001 ◽

2018 ◽

Vol 179 ◽

pp. 01001

Author(s):

Jie Wu

Keyword(s):

Cauchy Problem ◽

Heat Conductivity ◽

A Priori Estimates ◽

Three Dimensional ◽

Global Solutions ◽

Local Solution ◽

Viscous Fluids ◽

Heat Conducting ◽

The Cauchy Problem ◽

Incompressible Viscous Fluids

In this paper, we consider the Cauchy problem of non-stationary motion of heatconducting incompressible viscous fluids in ℝ3. About the heat-conducting incompressible viscous fluids, there are many mathematical researchers study the variants systems when the viscosity and heat-conductivity coefficient are positive. For the heat-conductive system, it is difficulty to get the better regularity due to the gradient of velocity of fluid own the higher order term. It is hard to control it. In order to get its global solutions, we must obtain the a priori estimates at first, then using fixed point theorem, it need the mapping is contracted. We can get a local solution, then applying the criteria extension. We can extend the local solution to the global solutions. For the two dimensional case, the Gagliardo-Nirenberg interpolation inequality makes use of better than the three dimensional situation. Thus, our problem will become more difficulty to handle. In this paper, we assume the coefficient of viscosity is a constant and the coefficient of heat-conductivity satisfying some suitable conditions. We show that the Cauchy problem has a global-in-time strong solution (u,θ) on ℝ3 ×(0, ∞).

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Microstructure and Properties of the Composite on the Basis of Copper and Diamond

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.685.607 ◽

2016 ◽

Vol 685 ◽

pp. 607-610 ◽

Cited By ~ 1

Author(s):

Aleksander S. Ivashutenko ◽

Nikita V. Martyushev ◽

Yuriy Yu. Drozdov

Keyword(s):

Spark Plasma Sintering ◽

Heat Conductivity ◽

Pure Copper ◽

Three Dimensional ◽

Diamond Powder ◽

Heat Conducting ◽

Plasma Sintering ◽

Spark Plasma ◽

Composite Heat ◽

Sps Sintering

The paper presents the experimental material on obtaining and researching of three-dimensional composite heat-conducting copper-diamond materials in the system of spark plasma sintering. Earlier [1-5], it was established that in order to achieve the effect of the increased heat conductivity of a composite it is necessary to create the conditions hindering the movement of heat flux on the interface boundary. In this work we have attempted to obtain the material with heat conductivity higher than that of pure copper due to addition of diamond powder and synthesis of the composite in the system of spark plasma sintering. For comparison, we have considered copper and diamond compositions in the ratios of 50/50 and 40/60 correspondingly. The results of the heat conductivity analysis have not exceeded the indices of pure copper; however, according to SEM data, it has been found that at SPS-sintering local domains with enhanced adhesion form on the surfaces of diamonds.

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RECONSTRUCTION OF 3D MODELS FROM POINT CLOUDS WITH HYBRID REPRESENTATION

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-2-449-2018 ◽

2018 ◽

Vol XLII-2 ◽

pp. 449-454

Author(s):

P. Hu ◽

Z. Dong ◽

P. Yuan ◽

F. Liang ◽

B. Yang

Keyword(s):

3D Reconstruction ◽

Three Dimensional ◽

Region Growing ◽

Reconstruction Algorithm ◽

Point Clouds ◽

3D Models ◽

Building Structures ◽

Freeform Surfaces ◽

Irregular Surfaces ◽

Regular Structures

The three-dimensional (3D) reconstruction of urban buildings from point clouds has long been an active topic in applications related to human activities. However, due to the structures significantly differ in terms of complexity, the task of 3D reconstruction remains a challenging issue especially for the freeform surfaces. In this paper, we present a new reconstruction algorithm which allows the 3D-models of building as a combination of regular structures and irregular surfaces, where the regular structures are parameterized plane primitives and the irregular surfaces are expressed as meshes. The extraction of irregular surfaces starts with an over-segmented method for the unstructured point data, a region growing approach based the adjacent graph of super-voxels is then applied to collapse these super-voxels, and the freeform surfaces can be clustered from the voxels filtered by a thickness threshold. To achieve these regular planar primitives, the remaining voxels with a larger flatness will be further divided into multiscale super-voxels as basic units, and the final segmented planes are enriched and refined in a mutually reinforcing manner under the framework of a global energy optimization. We have implemented the proposed algorithms and mainly tested on two point clouds that differ in point density and urban characteristic, and experimental results on complex building structures illustrated the efficacy of the proposed framework.

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Numerical Simulation of Heat Transfer in Shear Flow of Liquid-Solid Two-Phase Media by Immersed Solid Approach

Volume 1A: Symposia, Part 2 ◽

10.1115/ajkfluids2015-07513 ◽

2015 ◽

Cited By ~ 1

Author(s):

Takeo Kajishima ◽

Katsuya Kondo ◽

Shintaro Takeuchi

Keyword(s):

Heat Transfer ◽

Numerical Simulation ◽

Thermal Convection ◽

Heat Conductivity ◽

Three Dimensional ◽

Effect Of Temperature ◽

Two Dimensional ◽

Two Phase ◽

Dimensional Simulation ◽

Conductive Particles

We developed a direct numerical simulation (DNS) method of solid-fluid two-phase flows to study the effects of heat conductivity within a solid particle and the particle motion on the heat transfer. Heat transfer and particle behaviors were studied for different ratios of heat conductivity (solid to liquid) and solid volume fractions. The simulation results emphasize the effect of temperature distributions within the particles, and the heat transfer through each particle plays an important role for the motion of the particulate flow. The particle-laden flow in a two-dimensional channel of instable thermal stratification, namely hot wall at the bottom and cold wall at the top, is simulated. In the two-dimensional computation, the heat transfer attenuates by increasing the neutral conductive particles because of the resistance to the thermal convection. In case of highly conductive particles, the thermal convection and conductions are enhanced to some extent of addition but the overload of particles suddenly reduces the intensity of convection, resulting in the lower heat transfer. The inverse gradient of mean temperature is observed particularly in case of moderate loading of neutral conductive particles. It is due to the modulation of the profile of convection cells. Most of the above-mentioned findings are reproduced by the fully three-dimensional simulation.

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Three-dimensional self-assembly using dipolar interaction

Science Advances ◽

10.1126/sciadv.aba2007 ◽

2020 ◽

Vol 6 (19) ◽

pp. eaba2007 ◽

Cited By ~ 6

Author(s):

Leon Abelmann ◽

Tijmen A. G. Hageman ◽

Per A. Löthman ◽

Massimo Mastrangeli ◽

Miko C. Elwenspoek

Keyword(s):

Self Assembly ◽

Permanent Magnets ◽

Three Dimensional ◽

Dipolar Interaction ◽

The Self ◽

Design Rule ◽

One Dimensional ◽

Regular Structures ◽

Specific Shape ◽

Dimensional Crystal

Interaction between dipolar forces, such as permanent magnets, generally leads to the formation of one-dimensional chains and rings. We investigated whether it was possible to let dipoles self-assemble into three-dimensional structures by encapsulating them in a shell with a specific shape. We found that the condition for self-assembly of a three-dimensional crystal is satisfied when the energies of dipoles in the parallel and antiparallel states are equal. Our experiments show that the most regular structures are formed using cylinders and cuboids and not by spheroids. This simple design rule will help the self-assembly community to realize three-dimensional crystals from objects in the micrometer range, which opens up the way toward previously unknown metamaterials.

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Combining Interference Lithography and Two-Photon Lithography for Fabricating Large-Area Photonic Crystal Structures with Controlled Defects

Applied Sciences ◽

10.3390/app11146559 ◽

2021 ◽

Vol 11 (14) ◽

pp. 6559

Author(s):

Hongsub Jee ◽

Min-Joon Park ◽

Kiseok Jeon ◽

Chaehwan Jeong ◽

Jaehyeong Lee

Keyword(s):

Photonic Crystal ◽

Crystal Structures ◽

Three Dimensional ◽

Interference Lithography ◽

Large Area ◽

Regular Array ◽

Two Photon ◽

Regular Structures ◽

Patterned Structures ◽

Fast Processing

Interference lithography is a promising method for fabricating large-area, defect-free three-dimensional photonic crystal structures which can be used for facilitating the realization of photonic devices with a fast processing time. Although they can be used in waveguides, resonators, and detectors, their repeated regular array patterns can only be used for limited applications. In this study, we demonstrate a method for fabricating large-area photonic crystal structures with controlled defects by combining interference lithography and two-photon lithography using a light-curable resin. By combining regular array structures and controlled patterns, monotonous but large-area regular structures can be obtained. Furthermore, the patterned structures have considerable potential for use in various applications, such as solar cells, sensors, photodetectors, micro-/nano-electronics, and cell growth.

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A Self-Reconfigurable Modular Robot: Reconfiguration Planning and Experiments

The International Journal of Robotics Research ◽

10.1177/0278364902021010835 ◽

2002 ◽

Vol 21 (10-11) ◽

pp. 903-915 ◽

Cited By ~ 69

Author(s):

Eiichi Yoshida ◽

Satoshi Murata ◽

Akiya Kamimura ◽

Kohji Tomita ◽

Haruhisa Kurokawa ◽

...

Keyword(s):

Lower Layer ◽

Three Dimensional ◽

Difficult Problem ◽

Planning Method ◽

Planning Problem ◽

Modular Robot ◽

Regular Structures ◽

Reconfiguration Planning ◽

Locomotion Mode ◽

The Many

In this paper we address a reconfiguration planning method for locomotion of a homogeneous modular robotic system and we conduct an experiment to verify that the planned locomotion can be realized by hardware. Our recently developed module is self-reconfigurable. A group of the modules can thus generate various three-dimensional robotic structures and motions. Although the module itself is a simple mechanism, self-reconfiguration planning for locomotion presents a computationally difficult problem due to the many combinatorial possibilities of modular configurations. In this paper, we develop a two-layered planning method for locomotion of a class of regular structures. This locomotion mode is based on multi-module blocks. The upper layer plans the overall cluster motion called flow to realize locomotion along a given desired trajectory; the lower layer determines locally cooperative module motions, called motion schemes, based on a rule database. A planning simulation demonstrates that this approach effectively solves the complicated planning problem. Besides the fundamental motion capacity of the module, the hardware feasibility of the planning locomotion is verified through a self-reconfiguration experiment using the prototype modules we have developed.

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