Bioheat Transfer in a Branching Countercurrent Network During Hyperthermia

1989 ◽  
Vol 111 (4) ◽  
pp. 263-270 ◽  
Author(s):  
C. K. Charny ◽  
R. L. Levin
Keyword(s):  
Muscle Blood Flow ◽  
Equation Model ◽  
Bioheat Transfer ◽  
Tissue Temperature ◽  
Transfer Model ◽  
Temperature Profiles ◽  
The Mean ◽  
Pennes Model ◽  
Theoretical Results ◽  
Two Parameter

A bioheat transfer model which computes the spatial variations in the arteriole, venule, and muscle temperatures in a human extremity under both resting and hyperthermic conditions is presented. This model uses the two-parameter model first proposed by Baish et al. [2] to account for the heat exchange between tissue and the paired arterioles and venules that comprise the microcirculation. Thermoregulation of the muscle blood flow during hyperthermia is also incorporated into the model. Results show that even when the paired arteriole and venule are assumed to have equal radii, the mean temperature under both steady and transient conditions is not equal to the mean of the arteriole and venule blood temperatures. Tissue temperature profiles during hyperthermia computed with the three-equation model presented in this study are similar in shape and magnitude to those predicted by the traditional one-equation Pennes bioheat transfer model [1]. This is due primarily to the influence of thermoregulatory mechanism in the heated muscle. The unexpected agreement is significant given the inherent relative simplicity of the traditional Pennes model. An “experimental” thermal conductivity is presented to relate the theoretical results to experimental procedures that are widely used to estimate the enhancement of conductivity by perfusion.

Ocular surface temperature differences in glaucoma

2021 ◽  
pp. 112067212110237
Author(s):  
Ari Leshno ◽  
Ori Stern ◽  
Yaniv Barkana ◽  
Noa Kapelushnik ◽  
Reut Singer ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Thermal Imaging ◽  
Ocular Surface ◽  
Open Angle Glaucoma ◽  
Tissue Temperature ◽  
Body Temperatures ◽  
Current Thinking ◽  
Imaging Camera ◽  
The Mean ◽  
The Difference

Purpose: Accumulating evidence suggests that neuroinflammation and immune response are part of the sequence of pathological events leading to optic nerve damage in glaucoma. Changes in tissue temperature due to inflammation can be measured by thermographic imaging. We investigated the ocular surface temperature (OST) profile of glaucomatous eyes to better understand the pathophysiology of these conditions. Methods: Subjects diagnosed with glaucoma (primary open angle glaucoma [POAG] or pseudo exfoliation glaucoma [PXFG]) treated at the Sam Rothberg Glaucoma Center (11/2019–11/2020.) were recruited. Healthy subjects with no ocular disease served as controls. The Therm-App thermal imaging camera was used for OST acquisition. Room and body temperatures were recorded, and the mean temperatures of the medial cantus, lateral cantus, and cornea were calculated with image processing software. Results: Thermographic images were obtained from 52 subjects (52 eyes: 25 POAG and 27 PXFG) and 66 controls (66 eyes). Eyes with glaucoma had a significantly higher OST compared to controls (mean 0.9 ± 0.3°C, p < 0.005). The difference between the two groups remained significant after adjustment for age, sex, intraocular pressure (IOP) and room and body temperatures. Lens status and topical IOP-lowering medication did not significantly affect OST. A subgroup analysis revealed that the OST was higher among eyes with POAG compared to eyes with PXFG, but not significantly. Conclusions: Differences in the OST between glaucomatous and normal eyes strengthens current thinking that inflammation affects the pathophysiology of glaucoma. Longitudinal studies are warranted to establish the prognostic value of thermographic evaluations in these patients.

Study of a Vibratory Feeder with Repulsive Surface Which Has Directional Characteristic

1980 ◽  
Vol 102 (1) ◽  
pp. 94-101 ◽  
Author(s):  
S. Okabe ◽  
Y. Yokoyama
Keyword(s):  
Experimental Studies ◽  
Directional Characteristic ◽  
Vibratory Feeder ◽  
The Mean ◽  
Theoretical Results

This paper treats the motion of a particle on a vibratory feeder whose track has directional characteristic in repulsive motion, for examples, obliquely bristled track, obliquely sliced track and so on. Under some assumptions, the practical equation for predicting the mean conveying velocity is shown and the relations between conveying condition and the mean conveying velocity are clarified theoretically. These relations are shown in various diagrams. Referring these diagrams, the optimum conveying conditions are discussed also. The theoretical results show that the mean conveying velocity is considerably larger than that of the ordinary feeder. The theoretical results are confirmed by experimental studies.

Performance limitation of networked systems with controller and communication filter co-design

2016 ◽  
Vol 40 (4) ◽  
pp. 1167-1176 ◽  
Author(s):  
Jie Wu ◽  
Xi-Sheng Zhan ◽  
Xian-He Zhang ◽  
Tao Han ◽  
Hong-Liang Gao
Keyword(s):  
Networked Systems ◽  
Channel Noise ◽  
Frequency Domain Method ◽  
Minimum Phase ◽  
Error Signal ◽  
Optimal Network ◽  
Performance Limitation ◽  
The One ◽  
Theoretical Results ◽  
Two Parameter

This paper addresses the performance limitation problem of networked systems by co-designing the controller and communication filter. The tracking performance index is measured by the energy of the error signal. Explicit expressions of the performance limitation are obtained by applying the controller and communication filter co-design, and the optimal network filter is obtained by applying the frequency domain method. It is shown that the performance limitation is closely related to the unstable poles and the non-minimum phase zeros of a given plant under the one-parameter compensator structure, whereas, under the two-parameter compensator structure, the performance limitation is unrelated to the unstable poles of a given plant. It is also demonstrated that the performance limitation can be improved and the effect of the channel noise can be eliminated by using the controller and communication filter co-design. Finally, some typical examples are presented to illustrate the theoretical results.

Vibratory Feeding by Nonsinusoidal Vibration—Optimum Wave Form

1985 ◽  
Vol 107 (2) ◽  
pp. 188-195 ◽  
Author(s):  
S. Okabe ◽  
Y. Kamiya ◽  
K. Tsujikado ◽  
Y. Yokoyama
Keyword(s):  
Experimental Results ◽  
Wave Form ◽  
Velocity Wave ◽  
The Mean ◽  
Straight Lines ◽  
Vibratory Conveyor ◽  
Theoretical Results ◽  
Vibratory Feeding

This paper presents the conveying velocity on a vibratory conveyor whose track is vibrated by nonsinusoidal vibration. The velocity wave form of the vibrating track is approximated by six straight lines, and five distortion factors of the wave form are defined. Considering the modes of motion of the particle, the mean conveying velocity is calculated for various conditions. Referring to these results, the optimum wave form is clarified analytically. The theoretical results show that the mean conveying velocity is considerably larger than that of ordinary feeders if the proper conveying conditions are chosen. The theoretical results are confirmed by experimental results.

scholarly journals The Probability That a Measurement Falls within a Range of Standard Deviations from an Estimate of the Mean

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Louis M. Houston
Keyword(s):  
Confidence Interval ◽  
Sample Size ◽  
General Equation ◽  
Sample Sizes ◽  
The Mean ◽  
Standard Deviations ◽  
Intermediate Value ◽  
Theoretical Results

We derive a general equation for the probability that a measurement falls within a range of n standard deviations from an estimate of the mean. So, we provide a format that is compatible with a confidence interval centered about the mean that is naturally independent of the sample size. The equation is derived by interpolating theoretical results for extreme sample sizes. The intermediate value of the equation is confirmed with a computational test.

Two parameters are required for a Budyko function to describe the land-atmosphere interaction

2021 ◽  
Author(s):  
Daeha Kim ◽  
Jong Ahn Chun
Keyword(s):  
Land Surface ◽  
River Basins ◽  
Control Surface ◽  
Primary Control ◽  
Evaporative Demand ◽  
Atmosphere Interaction ◽  
The Mean ◽  
Two Parameters ◽  
Two Parameter ◽  
Surface Changes

&lt;p&gt;While the Budyko framework has been a simple and convenient tool to assess runoff (Q) responses to climatic and surface changes, it has been unclear how parameters of a Budyko function represent the vertical land-atmosphere interactions. Here, we explicitly derived a two-parameter equation by correcting a boundary condition of the Budyko hypothesis. The correction enabled for the Budyko function to reflect the evaporative demand (E&lt;sub&gt;p&lt;/sub&gt;) that actively responds to soil moisture deficiency. The derived two-parameter function suggests that four physical variables control surface runoff; namely, precipitation (P), potential evaporation (E&lt;sub&gt;p&lt;/sub&gt;), wet-environment evaporation (E&lt;sub&gt;w&lt;/sub&gt;), and the catchment properties (n). We linked the derived Budyko function to a definitive complementary evaporation principle, and assessed the relative elasticities of Q to climatic and land surface changes. Results showed that P is the primary control of runoff changes in most of river basins across the world, but its importance declined with climatological aridity. In arid river basins, the catchment properties play a major role in changing runoff, while changes in E&lt;sub&gt;p&lt;/sub&gt; and E&lt;sub&gt;w&lt;/sub&gt; seem to exert minor influences on Q changes. It was also found that the two-parameter Budyko function can capture unusual negative correlation between the mean annual Q and E&lt;sub&gt;p&lt;/sub&gt;. This work suggests that at least two parameters are required for a Budyko function to properly describe the vertical interactions between the land and the atmosphere.&lt;/p&gt;

Simultaneous Measurements of Droplet Size, Temperature, and Velocity Using an Integrated Phase-Doppler/Rainbow Thermometer

2001 ◽  
Author(s):  
Matt O’ Donnell ◽  
Sumanta Acharya
Keyword(s):  
Refractive Index ◽  
Detailed Examination ◽  
Temperature Profiles ◽  
Droplet Temperature ◽  
Radial Temperature ◽  
Temperature Correlation ◽  
Simultaneous Measurements ◽  
Laser Diagnostic ◽  
The Mean ◽  
And Performance

Abstract This work summarizes efforts to determine the accuracy and performance characteristics of a new and novel laser diagnostic to measure instantaneous, in flight, droplet temperatures. The instrument uses the location of the rainbow peak to deduce the refractive index of the droplet, which in turn is related to the droplet temperature. Preliminary experiments were undertaken in order to understand the fundamental operating principles and limitations of the instrument. These experiments measured the temperature of an isothermal, single stream of monodisperse droplets. These measurements indicate that the mean refractive index can be measured with a standard deviation as low as 0.0001m. Once the operation of the refractometer was proved under isothermal conditions, the measurement of droplet temperatures in a swirl-stabilized combustor was performed. These measurements indicate that the strength of the rainbow signal is significantly hampered by the noise induced by the flame. Preliminary temperature measurements with the combustor equipped with 45° vanes showed relatively constant radial temperature profiles (∼55–60°C) at locations less than 2 inches from the nozzle exit. A detailed examination of the temperature correlation with velocity and diameter revealed that larger and faster moving droplets dominate the distributions. Thus, the smaller droplets that are suspected of having the highest temperatures are inadequately represented in the mean droplet temperature.

Treatment of Arrhythmias by Radiofrequency Ablation

2013 ◽  
Author(s):  
M. Erol Ulucakli ◽  
Evan P. Sheehan
Keyword(s):  
Radiofrequency Ablation ◽  
Cardiac Tissue ◽  
Clinical Applications ◽  
Bioheat Transfer ◽  
Temperature Profiles ◽  
Cellular Injury ◽  
Rf Ablation ◽  
Transcatheter Therapy ◽  
Wide Range ◽  
Primary Modality

Radiofrequency ablation may be described as a thermal strategy to destroy tissue by increasing its temperature and causing irreversible cellular injury. Radiofrequency ablation is a relatively new modality which has found use in a wide range of medical applications and gained acceptance. RF ablation has been used to destroy tumors in the liver, prostate, breasts, lungs, kidneys, bones, and eyes. One of the early clinical applications was its use in treating supraventricular arrhythmias by selectively destroying cardiac tissue. Radiofrequency ablation has become established as the primary modality of transcatheter therapy for the treatment of symptomatic arrhythmias. Radiofrequency catheter ablation of cardiac arrhythmias was investigated using a finite-element based solution of the bioheat transfer equation. Spatial and temporal temperature profiles in the cardiac tissue were visualized.

The Effect of Froude Number on Entrainment in Two-Dimensional Line Plumes

1981 ◽  
Vol 103 (3) ◽  
pp. 471-477 ◽  
Author(s):  
W. F. Phillips
Keyword(s):  
Froude Number ◽  
Large Distance ◽  
Universal Constant ◽  
Temperature Profiles ◽  
Two Dimensional ◽  
Development Length ◽  
High Discharge ◽  
Entrainment Coefficient ◽  
Theoretical Results

Theoretical results are presented which predict the entrainment coefficient in a forced plume as a function of the local Froude number. The model does not require any external specification of the velocity and temperature profiles. The Froude number for any plume, in a motionless isothermal ambient, approaches a universal constant, at a large distance above the source. However, it is shown here that the development length for the Froude number, in plumes with high discharge Froude number, is of the order of a few hundred times the discharge width.

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