scholarly journals The thermal effects of pulsed ultrasound

1981 ◽  
Vol 37 (1) ◽  
pp. 10-12 ◽  
Author(s):  
V. Sandler ◽  
P. Feingold
Keyword(s):  
Heat Production ◽  
Thermal Effects ◽  
Continuous Beam ◽  
Pulsed Ultrasound ◽  
Temperature Changes ◽  
Pulse Ratio

Heat production by pulsed ultrasound was investigated. Four thermocouples were inserted into the thighs of each of six rabbits at specified depths. Temperature changes were recorded during insonation at different frequencies, intensities and duration of insonation. Significant thermal effects were recorded at both pulse ratios. These temperature increases were greater using a pulse ratio of 1:1 than a pulse ratio of 1:4, but less than those produced by a continuous beam.

Data-driven analysis on thermal effects and temperature changes of lithium-ion battery

2021 ◽  
Vol 482 ◽  
pp. 228983
Author(s):  
Shan Zhu ◽  
Chunnian He ◽  
Naiqin Zhao ◽  
Junwei Sha
Keyword(s):  
Lithium Ion Battery ◽  
Thermal Effects ◽  
Lithium Ion ◽  
Data Driven ◽  
Temperature Changes

Adaptation as a Mechanism for Gain Control in an Insect Thermoreceptor

2008 ◽  
Vol 100 (4) ◽  
pp. 2137-2144 ◽  
Author(s):  
Harald Tichy ◽  
Harald Fischer ◽  
Ewald Gingl
Keyword(s):  
Temperature Change ◽  
Thermal Effects ◽  
Gain Control ◽  
Input Function ◽  
High Gain ◽  
Oscillation Period ◽  
Rate Of Change ◽  
Temperature Changes ◽  
Precise Information ◽  
Instantaneous Temperature

Adaptation controls the gain of the input-function of the cockroach's cold cell during slowly oscillating changes in temperature. When the oscillation period is long, the cold cell improves its gain for the rate of temperature change at the expense of its ability to code instantaneous temperature. When the oscillation period is brief, however, the cold cell reduces this gain and improves its sensitivity for instantaneous temperature. This type of gain control has an important function. When the cockroach ventures from under cover and into moving air, the cold cell is confronted constantly with brief changes in temperature. To be of any use, a limit in the gain for the rate of change seems to be essential. Without such a limit, the cold cell will always indicate temperature change. The decrease in gain for the rate of change involves an increase in gain for instantaneous temperature. Therefore the animal receives precise information about the temperature at which the change occurs and can seek an area of different temperature. If the cockroach ventures back under cover, the rate of change will become slow. In this situation, a high gain improves the ability to signal slow temperature changes. The cockroach receives the early warning of slow fluctuations or even creeping changes in temperature. A comparison of the cold cell's responses with the temperature measured inside of small, cylindrical model objects indicates that coding characteristic rather than passive thermal effects of the structures enclosing the cold cell are responsible for the observed behavior.

Thermal Effects while Fatigue Cracking Growth under Bending

2013 ◽  
Vol 592-593 ◽  
pp. 700-703
Author(s):  
Dariusz Rozumek ◽  
Norbert Szmolke
Keyword(s):  
Crack Growth ◽  
Thermal Effects ◽  
Fatigue Cracking ◽  
Fatigue Tests ◽  
Temperature Gradients ◽  
Growth Path ◽  
Temperature Changes ◽  
Crack Growth Path ◽  
Molecular Friction

The paper presents the results of fatigue tests where temperature changes on specimen surfaces were registered. Some different materials were tested. A relation between the crack growth and temperature changes in the propagation place was found. The highest temperature gradients were measured on the crack growth path, and it was caused by molecular friction.

scholarly journals Dynamic Characteristics of an Elastic Structure with Thermal Effects

2020 ◽  
Vol 25 (2) ◽  
pp. 200-208
Author(s):  
Guanhua Xu ◽  
Jianzhong Fu ◽  
Wen He ◽  
Yuetong Xu ◽  
Zhiwei Lin ◽  
...  
Keyword(s):  
Modal Analysis ◽  
Dynamic Characteristics ◽  
Thermal Effects ◽  
Natural Frequencies ◽  
Elastic Structure ◽  
Mode Shapes ◽  
The Finite Element Method ◽  
Environmental Testing ◽  
Temperature Changes ◽  
Property Changes

The vibration table in a combination environmental testing device suffers from temperature changes, which cause the dynamic characteristics of the vibration structure to vary. The mechanism of the thermal effect on the dynamic characteristics of an elastic structure is presented, and a modal analysis with thermal effects based on the finite-element method (FEM) is carried out. The results show that the natural frequencies for each order decrease as the temperature increases, while the mode shapes of the vibrator do not change with temperature. Although thermal stress may affect natural frequencies due to the additional initial stress element stiffness, this stress can be neglected in the modal analysis because it is negligible relative to the effect of the material property changes with temperature.

Simulation of the Thermal Effects on Engineered Polymer Composite Ties

2019 ◽  
Author(s):  
Yin Gao ◽  
Mike McHenry
Keyword(s):  
Polymer Composite ◽  
Thermal Effects ◽  
Field Testing ◽  
Support Condition ◽  
Direct Sunlight ◽  
Temperature Changes ◽  
Service Testing ◽  
Bending Effect ◽  
Thermal Bending ◽  
Potential Alternative

Engineered polymer composite (EPC) ties offer a potential alternative to solid sawn timber ties. These materials are especially attractive for use in regions where wood is susceptible to degradation by moisture and decay organisms. However, recent research at the Transportation Technology Center’s (TTC) Facility for Accelerated Service Testing (FAST) in Pueblo, CO, found that track supported by EPC ties experienced more gage widening variation due to temperature changes than track supported by wood ties. Specifically, the track gage was about 0.2-in. wider in the afternoon than that in the morning on the EPC tie tracks. It is believed that the direct sunlight in the afternoon makes the top surface of the tie expand more than the other parts of the tie, thereby causing the EPC ties to bend and widen track gage. Another observation related to the EPC thermal bending effect is changes to the ballast support condition. When temperatures are cooler, EPC ties tend to experience a center-bound ballast support condition, therefore generating more bending stress on the ties. This paper presents results from computer simulations of the thermal behavior of EPC ties. Future study will focus on field testing to further understand the thermal effects in support of recommendations on the use of EPC ties.

An Analytical Model for a Clamped Isotropic Beam Under Thermal Effects

2002 ◽  
Author(s):  
Rodrigo F. A. Marques ◽  
Daniel J. Inman
Keyword(s):  
Boundary Conditions ◽  
Analytical Model ◽  
Thermal Effects ◽  
Natural Frequencies ◽  
Dynamical Behavior ◽  
Beam Theory ◽  
Optimization Procedure ◽  
Temperature Changes ◽  
Thermally Expand ◽  
Spring Constants

Structures and industrial equipment often operate in environments where temperature variations take place. Although thermal effects may be negligible in some cases, they have caused the unexpected failure of mechanical systems many times. Whether or not temperature has significant effects on the dynamical behavior of such machines and structures depends upon several aspects, amongst which are geometry, material properties and boundary conditions. In this paper we investigate the dynamical behavior of a clamped beam under the influence of a uniform, quasi-statically varying temperature field. An analytical model was used, based on Euler-Bernoulli’s beam theory with the introduction of the proper boundary conditions. Temperature effects are included in terms of an axial force that shows up when the beam tends to thermally expand, but this expansion is restrained by the clamping. Preliminary results do not agree with experimental data, since perfect clamping is difficult to achieve in practice. Finally the model is updated with the inclusion of axial and torsional springs connecting the beam to the support. The spring constants were calculated through optimization procedure to minimize the differences between the natural frequencies obtained from the analytical model and the corresponding experimental ones. Agreement with experimental results is reasonable up to the 4th mode of the beam. In the future, this analytical model is to be used for design and simulation of an active controller that accounts for temperature changes in the structure.

Thermal effects of dorsal head immersion in cold water on nonshivering humans

2005 ◽  
Vol 99 (5) ◽  
pp. 1958-1964 ◽  
Author(s):  
Gordon G. Giesbrecht ◽  
Tamara L. Lockhart ◽  
Gerald K. Bristow ◽  
Allan M. Steinman
Keyword(s):  
Heat Loss ◽  
Heat Production ◽  
Thermal Effects ◽  
Cold Water ◽  
The Body ◽  
Whole Body ◽  
Esophageal Temperature ◽  
Confounding Effect ◽  
Core Cooling ◽  
Stimulation Of

Personal floatation devices maintain either a semirecumbent flotation posture with the head and upper chest out of the water or a horizontal flotation posture with the dorsal head and whole body immersed. The contribution of dorsal head and upper chest immersion to core cooling in cold water was isolated when the confounding effect of shivering heat production was inhibited with meperidine (Demerol, 2.5 mg/kg). Six male volunteers were immersed four times for up to 60 min, or until esophageal temperature = 34°C. An insulated hoodless dry suit or two different personal floatation devices were used to create four conditions: 1) body insulated, head out; 2) body insulated, dorsal head immersed; 3) body exposed, head (and upper chest) out; and 4) body exposed, dorsal head (and upper chest) immersed. When the body was insulated, dorsal head immersion did not affect core cooling rate (1.1°C/h) compared with head-out conditions (0.7°C/h). When the body was exposed, however, the rate of core cooling increased by 40% from 3.6°C/h with the head out to 5.0°C/h with the dorsal head and upper chest immersed ( P < 0.01). Heat loss from the dorsal head and upper chest was approximately proportional to the extra surface area that was immersed (∼10%). The exaggerated core cooling during dorsal head immersion (40% increase) may result from the extra heat loss affecting a smaller thermal core due to intense thermal stimulation of the body and head and resultant peripheral vasoconstriction. Dorsal head and upper chest immersion in cold water increases the rate of core cooling and decreases potential survival time.

scholarly journals Temperature changes accompanying signal propagation in axons

2019 ◽  
Vol 44 (3) ◽  
pp. 277-284 ◽  
Author(s):  
Kert Tamm ◽  
Jüri Engelbrecht ◽  
Tanel Peets
Keyword(s):  
Differential Equations ◽  
Action Potential ◽  
Mathematical Models ◽  
Heat Production ◽  
Mathematical Description ◽  
Signal Propagation ◽  
Nerve Fibers ◽  
The Novel ◽  
Temperature Changes ◽  
Whole Process

Abstract In this paper mathematical models are formulated in order to simulate heat production and corresponding temperature changes which accompany the propagation of an action potential. Based on earlier experimental results, several models are proposed. Together with the earlier system of coupled differential equations derived by the authors for describing the electrical and mechanical components of signaling in nerve fibers, the novel results permit to cast the whole process of signaling into one system. The emphasis is on the mathematical description of coupling forces. The numerical results are qualitatively similar to experiments.

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