A one dimensional heat transfer model for wolverine (gulo-gulo) hair

2018 ◽  
Vol 30 (4) ◽  
pp. 548-558
Author(s):  
HongYan Liu ◽  
Addie Bahi ◽  
Frank K. Ko
Keyword(s):  
Heat Transfer ◽  
Cold Weather ◽  
Transfer Model ◽  
Counting Method ◽  
Content Type ◽  
Box Counting ◽  
Proposed Model ◽  
Extreme Cold ◽  
Box Counting Method ◽  
Good Agreement

Purpose Wolverine hairs with superior heat transfer properties have been used as fur ruffs for extreme cold-weather clothing. In order to understand the exclusive mechanism of wolverine surviving in the cold areas of circumpolar, the purpose of this paper is to establish a one-dimensional fractional heat transfer equation to reveal the hidden mechanism for the hairs, and also calculate the fractal dimension of the wolverine hair using the box counting method to verify the proposed theory. The observed results (from the proposed model) found to be in good agreement with the box counting method. This model can explain the phenomenon which offers the theoretical foundation for the design of extreme cold weather clothing. Design/methodology/approach The authors calculated the fractal dimension of the wolverine hair using the box counting method to verify the proposed theory. The observed results (from the proposed model) found to be in good agreement with the box counting method. Findings The box counting method proves that the theoretical model is applicable. Originality/value The authors propose the first heat transfer model for the wolverine hair.

scholarly journals A two-stage heat transfer model for the peripheral layers of a grain store

2003 ◽  
Vol 7 (3) ◽  
pp. 147-164
Author(s):  
Alexsandar Antic ◽  
James M. Hill
Keyword(s):  
Heat Transfer ◽  
Present Model ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Two Stage ◽  
Peripheral Layer ◽  
Proposed Model ◽  
Grain Bulk ◽  
Insight Into ◽  
Good Agreement

An understanding of the flow of heat in grain store structures, in particular, within the peripheral layer, is important from many industrial perspectives. To analyse the heat transfer within such regions a mathematical model known as the two-stage heat transfer model is proposed. This model makes a distinction between the air and grain within the grain bulk, and thus takes into consideration the fact that the rate of heat transfer through the grain is different to that through the interstitial air surrounding the grain. Such a model lends itself to a solution via Laplace transforms and approximate analytical results are obtained for small and large times. In addition, the Stehfest numerical algorithm is used for the inversions and very good agreement is obtained between the two approaches. The present model is compared to a previously developed double-diffusivity heat transfer model by the authors, and good agreement is obtained. At present, no experimental data is available to validate the model as it is very difficult to measure the air and grain temperatures separately, particularly in the peripheral layer. The proposed model provides insight into the potential difference existing between the air and grain temperatures.

SOME FRACTAL CHARACTERS OF POROUS MEDIA

Fractals ◽  
2001 ◽  
Vol 09 (03) ◽  
pp. 365-372 ◽  
Author(s):  
BOMING YU ◽  
JIANHUA LI
Keyword(s):  
Porous Media ◽  
Fractal Theory ◽  
Unified Model ◽  
Counting Method ◽  
Statistical Property ◽  
Box Counting ◽  
Fractal Media ◽  
Proposed Model ◽  
Theoretical Predictions ◽  
Box Counting Method

In this paper, a unified model for describing the fractal characters of porous media is deduced. The theoretical predictions from the proposed unified model are compared with those from the previous models and from the box-counting method. The results from the proposed model are found to be in good agreement with both the previous models and box-counting method. The results also indicate that the proposed unified model is applicable to both the exactly and statistically self-similar fractal media. A statistical property of porous media is also described based on the basic fractal theory and technique. A criterion, for determining whether a porous medium can be characterized by fractal theory and technique or not, is proposed based on the fractal statistical property.

FRACTAL CHARACTERS OF PORE MICROSTRUCTURES OF TEXTILE FABRICS

Fractals ◽  
2001 ◽  
Vol 09 (02) ◽  
pp. 155-163 ◽  
Author(s):  
BOMING YU ◽  
L. JAMES LEE ◽  
HANQIANG CAO
Keyword(s):  
Fractal Dimension ◽  
Fractal Analysis ◽  
Reinforced Composites ◽  
Counting Method ◽  
Box Counting ◽  
Textile Fabrics ◽  
Different Types ◽  
Theoretical Predictions ◽  
Box Counting Method ◽  
Good Agreement

It is found that the pore microstructures of textile fabrics, widely used in the manufacture of fiber-reinforced composites, exhibit the fractal characters. The fractal behaviors are described by the proposed analytical method and measured by the box-counting method for the three different types of textile fabrics: plain woven, four-harness, bidirectional-stitched fiberglass mats. The pore area fractal dimension is derived analytically and found to be the function of the porosity and architectural parameters of fabrics. The results indicate that the fractal characters are isotropic although the fabrics are rothotropic in structures. The theoretical predictions by the proposed analytical model are in good agreement with those from the box-counting method, and this verifies the proposed fractal dimension model. The present fractal analysis may have the potential and significance on fractal analysis of transport properties (such as the permeability, dispersion, thermal and mechanical properties) in porous media.

Fractal and Convolutional Analysis for Deep Atmospheric Turbulence Using Machine Learning

2021 ◽  
Author(s):  
Nicholas Dudu ◽  
Arturo Rodriguez ◽  
Gael Moran ◽  
Jose Terrazas ◽  
Richard Adansi ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Atmospheric Turbulence ◽  
Isotropic Turbulence ◽  
Passive Scalar ◽  
Counting Method ◽  
Data Set ◽  
Box Counting ◽  
Box Counting Dimension ◽  
Self Similar ◽  
Box Counting Method

Abstract Atmospheric turbulence studies indicate the presence of self-similar scaling structures over a range of scales from the inertial outer scale to the dissipative inner scale. A measure of this self-similar structure has been obtained by computing the fractal dimension of images visualizing the turbulence using the widely used box-counting method. If applied blindly, the box-counting method can lead to misleading results in which the edges of the scaling range, corresponding to the upper and lower length scales referred to above are incorporated in an incorrect way. Furthermore, certain structures arising in turbulent flows that are not self-similar can deliver spurious contributions to the box-counting dimension. An appropriately trained Convolutional Neural Network can take account of both the above features in an appropriate way, using as inputs more detailed information than just the number of boxes covering the putative fractal set. To give a particular example, how the shape of clusters of covering boxes covering the object changes with box size could be analyzed. We will create a data set of decaying isotropic turbulence scenarios for atmospheric turbulence using Large-Eddy Simulations (LES) and analyze characteristic structures arising from these. These could include contours of velocity magnitude, as well as of levels of a passive scalar introduced into the simulated flows. We will then identify features of the structures that can be used to train the networks to obtain the most appropriate fractal dimension describing the scaling range, even when this range is of limited extent, down to a minimum of one order of magnitude.

Research on a precise differential box-counting method of eliminating image background

2016 ◽  
Author(s):  
Kexue Lai ◽  
Tao He ◽  
Cancan Li ◽  
Weisong Zhou ◽  
Liangen Yang
Keyword(s):  
Counting Method ◽  
Box Counting ◽  
Box Counting Method

Heat Transfer in Grinding-Hardening of a Cylindrical Component

2011 ◽  
Vol 325 ◽  
pp. 35-41 ◽  
Author(s):  
Thai Nguyen ◽  
Liang Chi Zhang ◽  
Da Le Sun
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Hardened Layer ◽  
Transfer Model ◽  
Plunge Grinding ◽  
Cylindrical Component ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Grinding Hardening ◽  
Good Agreement

A three-dimensional finite element heat transfer model incorporating a moving heat source was developed to investigate the heat transfer mechanism in grinding-hardening of a cylindrical component. The model was applied to analyze the grinding-hardening of quenchable steel 1045 by two grinding methods, traverse and plunge grinding. It was found that the heat generated can promote the martensitic phase transformation in the ground workpiece. As a result, a hardened layer with a uniform thickness can be produced by traverse grinding. However, the layer thickness generated by plunge grinding varies circumferentially. The results are in good agreement with the experimental observations.

scholarly journals Application of An Exponential Mathematical Law of Cardiac Dynamics In 16 Hours

2021 ◽  
Author(s):  
Javier Oswaldo Rodríguez Velásquez ◽  
Sandra Catalina Correra Herrera ◽  
Yesica Tatiana Beltrán Gómez ◽  
Jorge Gómez Rojas ◽  
Signed Esperanza Prieto Bohórquez ◽  
...  
Keyword(s):  
Kappa Coefficient ◽  
Medical Attention ◽  
Chaotic Attractors ◽  
Counting Method ◽  
Statistical Validation ◽  
Overlapping Grids ◽  
Box Counting ◽  
Cardiac Dynamics ◽  
Box Counting Method ◽  
Time Required

Abstract Introduction and objectives: nonlinear dynamics and fractal geometry have allowed the advent of an exponential mathematical law applicable to diagnose cardiac dynamics in 21 hours, however, it would be beneficial to reduce the time required to diagnose cardiac dynamics with this method in critical scenarios, in order to detect earlier complications that may require medical attention. The objective of this research is to confirm the clinical applicability of the mathematical law in 16 hours, with a comparative study against the Gold Standard. Methods: There were taken 450 electrocardiographic records of healthy patients and with cardiac diseases. A physical-mathematical diagnosis was applied to study cardiac dynamics, which consists of generating cardiac chaotic attractors based on the sequence of heart rate values during 16 hours, which were then measured with two overlapping grids according to the Box-Counting method to quantify the spatial occupation and the fractal dimension of each cardiac dynamic, with its respective statistical validation. Results: The occupation spaces of normal dynamics calculated in 16 hours were compatible with previous parameters established, evidencing the precision of the methodology to differentiate normality from abnormality. Sensitivity and specificity values of 100% were found, as well as a Kappa coefficient of 1. Conclusions: it was possible to establish differences between cardiac dynamics for 16 hours, suggesting that this method could be clinically applicable to analyze and diagnose cardiac dynamics in real time.

Heat Transfer Model and Analysis of Oil-Immersed Electrical Transformers with Heat Pipe Radiator

2012 ◽  
Vol 516-517 ◽  
pp. 312-315
Author(s):  
Guang Hua Li ◽  
Hong Lei Liu ◽  
De Jian Wang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Temperature Field ◽  
Heat Pipe ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Cooling Device ◽  
Transformer Design ◽  
Electrical Transformers ◽  
Good Agreement

This paper has formulated a heat transfer model for analyzing the cooling properties of a heat pipe cooling device of oil-immersed electrical transformer. Based on the model, the oil temperature field of a 30 KVA oil-immersed transformer has been numerical simulated, and experiments also had been conducted. Results showed that the numerical simulation has good agreement with experiment results. Results also showed that heat pipe radiator is feasible for oil-immersed electrical transformer cooling. The model can be used to analyze the oil temperature distribution properties in an oil-immersed electrical transformer with heat pipe cooling device, and provide theoretical guide for transformer design and improvement.

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