Analytical Temperature Distribution in a Multi-Layer Tissue Structure in the Presence of a Tumor

2013 ◽  
Author(s):  
Daipayan Sarkar ◽  
Ankur Jain ◽  
A. Haji-Sheikh
Keyword(s):  
Heat Generation ◽  
Basal Layer ◽  
Bioheat Transfer ◽  
Dimensional Structure ◽  
External Cooling ◽  
Study Results ◽  
Arbitrary Space ◽  
Cancerous Cells ◽  
Thermo Physical Properties ◽  
Good Agreement

Analytical study of bioheat transfer is of significant importance for a number of biomedical applications including cryopreservation of tissue and thermal therapy for cancer. A sound fundamental understanding of thermal behavior of tissue in response to an externally applied stimulus helps design effective therapies and protocols. This paper derives an analytical solution in a multi-layer two-dimensional structure with arbitrary, space-dependent heat generation occurring in each layer. This geometry effectively models multiple layers of skin, with heat generation due to cancerous cells in the basal layer. The Pennes bioheat transfer equation is solved for the multi-layer analytically, wherein the temperature in each layer is explicitly a function of space and the thermo-physical properties of the layer. The resulting analytical temperature profile agrees well with finite-element simulations and is also in good agreement with a previously published experimental study. Results derived in this work illustrate the effect of the presence of cancerous cells on the thermal profile of the skin. Further, the model helps to understand the effect of external cooling and heating stimuli.

Effect of K-wire Reuse and Drill Mode on Heat Generation in Bone

Hand ◽  
2021 ◽  
pp. 155894472110031
Author(s):  
Muturi G. Muriuki ◽  
Arun K. Reddy ◽  
Alex Tauchen ◽  
Robert M. Havey ◽  
Avinash G. Patwardhan ◽  
...  
Keyword(s):  
Cell Death ◽  
Cortical Bone ◽  
Heat Generation ◽  
Kirschner Wire ◽  
Heat Exposure ◽  
Critical Temperatures ◽  
Rotary Drilling ◽  
External Cooling ◽  
K Wires ◽  
Oscillating Mode

Background We examined the effect of Kirschner wire (K-wire) reuse and use of oscillating mode on heat generation within cortical bone. Methods Two trocar-tipped K-wires were drilled through the diaphysis of each of 30 human metacarpals and phalanges: one K-wire was inserted in rotary mode and another in oscillating mode. Each wire was reused once. Thermocouples placed within the dorsal and volar bone adjacent to the K-wire drill path measured temperatures throughout each test. Results Peak cortex temperatures were 25°C to 164°C. Rotary drilling achieves peak temperatures quicker (31 ± 78 seconds vs 44 ± 78 seconds, P = .19) than oscillating drilling, but insertion time is also less, resulting in lower overall heat exposure. This effect is also seen when the K-wire is reused (34 ± 70 seconds vs 41 ± 85 seconds, P = .4). The length of time that cortical bone was exposed to critical temperatures (47°C or more) was significantly higher when a wire was reused (36 ± 72 seconds vs 43 ± 82 seconds, P = .008). Peak temperatures greater than 70°C (a temperature associated with instantaneous cell death) were observed on many occasions. Conclusions Overall heat exposure may be higher if a K-wire is reused or inserted in oscillating mode. In the absence of external cooling, K-wire insertion into cortical bone can easily expose bone to temperatures that exceed 70°C and may increase the risk of osteonecrosis.

Heat and Mass Diffusion Including Shrinkage and Hygrothermal Stress during Drying of Holed Ceramics Bricks

2011 ◽  
Vol 312-315 ◽  
pp. 971-976 ◽  
Author(s):  
J. Barbosa da Silva ◽  
G. Silva Almeida ◽  
W.C.P. Barbosa de Lima ◽  
Gelmires Araújo Neves ◽  
Antônio Gilson Barbosa de Lima
Keyword(s):  
Moisture Content ◽  
Three Dimensional ◽  
Average Moisture Content ◽  
Stress Distributions ◽  
Drying Process ◽  
Convective Boundary ◽  
Volume Method ◽  
Hygrothermal Stress ◽  
Thermo Physical Properties ◽  
Good Agreement

The Aim of this Work Is to Present a Three-Dimensional Mathematical Modelling to Predict Heat and Mass Transport inside the Industrial Brick with Rectangular Holes during the Drying Including Shrinkage and Hygrothermalelastic Stress Analysis. the Numerical Solution of the Diffusion Equation, Being Used the Finite-Volume Method, Considering Constant Thermo-Physical Properties and Convective Boundary Conditions at the Surface of the Solid, it Is Presented and Analyzed. Results of the Temperature, Moisture Content and Stress Distributions, and Drying and Heating Kinetics Are Shown and Analyzed. Results of the Average Moisture Content and Surface Temperature of the Brick along the Drying Process Are Compared with Experimental Data (T = 80.0oC and RH = 4.6 %) and Good Agreement Was Obtained. it Was Verified that the Largest Temperature, Moisture Content and Stress Gradients Are Located in the Intern and External Vertexes of the Brick.

scholarly journals Tidewater glaciers: frontal flow acceleration and basal sliding

2000 ◽  
Vol 31 ◽  
pp. 217-221 ◽  
Author(s):  
Andreas Vieli ◽  
Martin Funk ◽  
Heinz Blatter
Keyword(s):  
Flow Model ◽  
Variable Viscosity ◽  
Basal Layer ◽  
Effective Pressure ◽  
Velocity Data ◽  
Tidewater Glaciers ◽  
Flow Acceleration ◽  
Basal Sliding ◽  
Glacier Flow ◽  
Good Agreement

AbstractA numerical glacier-flow model (finite-element method) is used to suggest the processes that control the flow behind the calving front of a tidewater glacier. The model is developed for grounded calving glaciers and includes an effective-pressure-dependent sliding law The sliding law is implemented by adding a soft basal layer with a variable viscosity The model is applied on Hansbreen, a tidewater calving glacier in Svalbard. Comparison between modeled surface velocities and observed velocity data shows good agreement. We conclude that the flow of a grounded calving glacier can be modeled with an effective-pressure-dependent sliding law

Determination of Adhesion Forces Between Smooth and Structured Solids

2012 ◽  
Author(s):  
Hartmut R. Fischer ◽  
Edwin R. M. Gelinck
Keyword(s):  
Adhesion Force ◽  
Smooth Surfaces ◽  
Adhesion Forces ◽  
Real Area Of Contact ◽  
Study Results ◽  
Colloidal Probes ◽  
Good Agreement ◽  
Real Area

The tendency of smooth surfaces to stick spontaneously to each other is becoming a serious problem, with: a) the increasing quality in surface finish for many components and systems, b) on miniaturization in mechanical components, and c) in demanded precision of positioning of parts in high-end equipment machines and systems. Surfaces tend to be made smoother in order to gain flatness or in order to fulfill the need for more precise and reproducible positioning of parts. Adhesion or even sticking of the surfaces is a major showstopper for these applications. There are several measures that can be taken in order to reduce spontaneous adhesion. Quantification of the effectiveness of the chosen solution is most often done using an AFM with probes varying from 1 nm to 8 micron of contact diameter. A serious disadvantage in measuring adhesion by sharp tips is the wear of the tips. Sharp tips wear easily, resulting in undefined contact areas. When the real area of contact is not well defined, the quantification of the adhesion force is not significant. In the current study results of AFM measurements from literature with different tip diameters of colloidal probes are compared with measurements we performed using AFM cantilevers with a plateau tip and using probes from large spheres using an alternative setup (UNAT). These methods give results that are in good agreement with values found in literature. Large contacting surface enhance the quality of the measured adhesion values. Another part of the study deals with a deliberately roughening of smooth surfaces to minimize (spontaneous) adhesion. Good agreement has been found with existing results. For the use of larger surfaces it is important that the surfaces to be tested are extremely clean. Particles on smooth surface do influence the measurements quite easily. Especially for larger areas, the possibility of encountering particles on the surface are more likely, when particles are present. For the measurements in this study a lot of care has been taken therefore to remove contamination: particles as well as contamination of organic origin.

Nanoparticle Heat Transfer and Its Application to Laser Hyperthermia

2007 ◽  
Author(s):  
B. Q. Li ◽  
C. Mi ◽  
C. Liu ◽  
G. Cheng ◽  
M. Fu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Generation ◽  
Local Heating ◽  
Experimental System ◽  
Resonance Excitation ◽  
Great Promise ◽  
Surface Plasma Resonance ◽  
Laser Hyperthermia ◽  
High Frequency Electromagnetic Field ◽  
Cancerous Cells

Nanoparticles-enabled laser hyperthermia holds a great promise as a new therapeutic treatment for cancer patients. This paper presents some preliminary data on the frequency tenability of nanostructures and on the heat transfer aspect of this process that results from the interaction between high frequency electromagnetic field and nanostructures. Maxwell equations are solved to predict heat generation from the surface plasma resonance excitation of a nano-sized particle or structure by a laser beam. An experimental system has also been setup to validate the concept of heat generation through particle-laser interaction. Results obtained on both model tissues and on mice are consistent with the model predictions. Experiments further show that concentrated local heating can be generated in cancerous cells for a thermal kill.

Studies on the Three-Dimensional Temperature Transients in the Canine Prostate During Transurethral Microwave Thermal Therapy

2000 ◽  
Vol 122 (4) ◽  
pp. 372-379 ◽  
Author(s):  
Jing Liu ◽  
Liang Zhu ◽  
Lisa X. Xu
Keyword(s):  
Three Dimensional ◽  
Blood Perfusion ◽  
Thermal Therapy ◽  
Bioheat Transfer ◽  
Target Tissue ◽  
Urethral Wall ◽  
Theoretical Predictions ◽  
Closed Form Analytical Solution ◽  
Good Agreement

Thermal therapy of benign prostatic hyperplasia requires accurate prediction of the temperature distribution induced by the heating within the prostatic tissue. In this study, the Pennes bioheat transfer equation was used to model the transient heat transfer inside the canine prostate during transurethral microwave thermal therapy. Incorporating the specific absorption rate of microwave energy in tissue, a closed-form analytical solution was obtained. Good agreement was found between the theoretical predictions and in-vivo experimental results. Effects of blood perfusion and the cooling at the urethral wall on the temperature rise were investigated within the prostate during heating. The peak intraprostatic temperatures attained by application of 5, 10, or 15 W microwave power were predicted to be 38°C,41°C, and 44°C. Results from this study will help optimize the thermal dose that can be applied to target tissue during the therapy. [S0148-0731(00)01004-9]

Two-Dimensional Transient Temperature Distribution in Cylindrical Bodies With Pulsating Time and Space-Dependent Boundary Conditions

1974 ◽  
Vol 96 (3) ◽  
pp. 300-306 ◽  
Author(s):  
J. A. Copley ◽  
W. C. Thomas
Keyword(s):  
Heat Flux ◽  
Boundary Conditions ◽  
Analytical Techniques ◽  
Transient Temperature ◽  
Two Dimensional ◽  
Transient Temperature Distribution ◽  
Gun Barrel ◽  
External Cooling ◽  
Periodic Heat ◽  
Good Agreement

The two-dimensional conduction equation is solved for a hollow cylinder subjected to a series of heat flux pulses on the inner boundary. The periodic heat flux is represented by an exponentially decreasing pulse with a spatial distribution of peak magnitude. The analytical techniques and representation of the boundary conditions apply to different situations involving pulsating boundary conditions. An application to the gun barrel heating problem is given. Calculated bore surface and internal temperature histories are in good agreement with experimental data. During the actual firing time in rapidly-firing guns, results show that external cooling is generally ineffective for controlling barrel bore surface temperature.

The Experimental Study and Numerical Simulation of Turbulent Flow in Pumping Forebay

2009 ◽  
Author(s):  
Chao Liu ◽  
Jiren Zhou ◽  
Li Cheng
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Turbulent Flow ◽  
Three Dimensional ◽  
Computational Results ◽  
Experiment Study ◽  
Study Results ◽  
Measurement Results ◽  
Good Agreement ◽  
Made In

The experiment study was made to optimize the design of a pumping forebay. The Combined-sills were made in the forebay to eliminate the circulation and vortices of the diffusing flow successfully. The Numerical simulation of three-dimensional turbulent flow is applied on the complicate fore-and-aft flow of sills. The computational results are compared with the measurement results of physical model. The calculated results are in good agreement with the experimental data. The flow pattern is obviously improved. The study results have been applied in the project which gives a uniform approach flow to the pumping sump.

scholarly journals Experimental and numerical investigations on the thermal performance of hemp such a bio-sourced insulation material: application to a Moroccan Mediterranean climate

2018 ◽  
Vol 7 (1.8) ◽  
pp. 157 ◽  
Author(s):  
Maryam Dlimi ◽  
Omar Iken ◽  
Rachid Agounoun ◽  
Amine Zoubir ◽  
Khalid Sbai
Keyword(s):  
Thermal Performance ◽  
Mediterranean Climate ◽  
Time Lag ◽  
Insulation Material ◽  
Concrete Wall ◽  
Heating And Cooling ◽  
Study Results ◽  
Cooling Loads ◽  
The City ◽  
Thermo Physical Properties

Thermal performance of hemp concrete and hemp wool such as ecological insulation was evaluated for the city of Meknes in Morocco, in comparison with polystyrene which is an organic insulation material. The study was done in three sections. First, a thermo-physical properties characterization was done using the EI700 device. Then, the study was done on a concrete wall subjected to periodic outdoor conditions. The three insulation materials are used and the effects of thickness, location and partitioning on the time lag and decrement factor were investigated. Finally, heating and cooling loads of a whole building with the use of six different walls configurations are calculated using TRNSYS software. Throughout the whole study, results show that hemp wool presented the best thermal performance, and the evaluation of its use such us an insulation material in Morocco and especially in Meknes was investigated.

A Microreactor System for the Analysis of the Fast Pyrolysis of Biomass

2010 ◽  
Vol 2 (3) ◽  
Author(s):  
Alexander Williams ◽  
J. Rhett Mayor
Keyword(s):  
Fast Pyrolysis ◽  
Heating Rates ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Study Results ◽  
Design Requirements ◽  
Layer Heating ◽  
The Individual ◽  
Pyrolysis Of Biomass ◽  
Good Agreement

A novel fast pyrolysis microreactor was developed to facilitate control over feedstock dwell time, pyrolysis temperature, and the individual collection of pyrolysis liquid and solid products. The design process followed is presented including design requirements, functional decomposition, commissioning tests, and the final microreactor design. A vibratory assisted spreading study was performed as particle agglomeration was a key challenge within the reactor design. The study results and analysis of variance are presented identifying the most significant factor and a best operating point. Analytical and experimental heat transfer analyses are also presented to validate the reactor’s thermal performance. Through the pairing of the analyses, projections for thin biomass layer heating rates are made resulting in estimates on the order of 400°C/s. Finally, experimental pyrolysis results are given showing fast pyrolysis conversion as a function of time and the process by which kinetic descriptors could be derived using this system’s results. Yield results are compared with literature and are found to be in good agreement with published fast pyrolysis results.

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