Analytical Solutions for Thermo-elastic Nonhomogeneous Equations

Transient temperature, another source to provide reservoir information besides transient pressure, has been received much attention in recent years. Different from the immediate response of transient pressure due to flow rate change, there are obvious time lags between the transient temperature change and flow rate change. In this paper, the nonsynchrony between PDG transient temperature, pressure and flow-rate data was quantitatively investigated with wavelet transform (WT). Field PDG data analysis show that transient pressure changes nearly at the same time of flow rate change. However, due to the adiabatic expansion/compression effect, the time lags between transient temperature and flow rate are significant and cannot be neglected. Field PDG data demonstrates that averagely transient temperature changes about 0.225 hours later than the flow rate. Accurately identifying the time of flow events from PDG temperature data is difficult. The identified flow event time from PDG temperature is the time when Joule-Thomson effect dominates the reservoir temperature change. The flow events with time periods less than the time lags cannot be identified from PDG temperature data due to the adiabatic expansion/compression effect. Compared with the Haar wavelet, the the second derivative of the Gaussian wavelet can more accurately identify flow events from PDG temperature data. This study will be useful for improving the accuracy of transient identification from PDG data, and can benefit transient temperature analysis by clarifying the time lags due to adiabatic expansion/compression effect, and synchronize PDG transient temperature, pressure and flow-rate data for better data processing and analysis.

High-speed impact on spacecraft by space debris poses a threat. When a high-speed projectile collides with target, it is conceivable that the heat created by impact causes severe damage at impact point. Investigation of the temperature is necessary for elucidation of high-speed impact phenomena. However, it is very difficult to measure the temperature with standard methods for two main reasons. One reason is that a thermometer placed on the target is instantaneously destroyed upon impact. The other reason is that there is not enough time resolution to measure the transient temperature changes. In this study, the measurement of plasma induced by high-speed impact was investigated to estimate temperature changes near the impact point. High-speed impact experiments were performed with a vertical gas gun. The projectile speed was approximately 700 m/s, and the target material was A5052. The experimental data to calculate the plasma parameters of electron temperature and electron density were measured by triple probe method. In addition, the diffusion behavior of plasma was observed by optical visualization technique using high-speed camera. The frame rate and the exposure time were 260 kfps and 1.0 μs, respectively. These images are considered to be one proof to show the validity of plasma measurement. The experimental results showed that plasma signals were detected for around 70 μs, and the rising phase of the wave form was in good agreement with timing of optical visualization image when the plasma arrived at the tip of triple probe.

Transient changes of temperature and current were numerically analyzed in BaTiO3 semiconductors with a multilayer structure to which a constant electric field was applied. The numerical analysis required the radiation coefficient of the multilayer sample and the temperature dependence of resistivity of the material as input data. Temperature distribution of the sample was modeled to be uniform since the material possesses positive temperature coefficients of resistivity in the temperature range above the Curie point. The results of the numerical analysis agreed qualitatively with experimental results in the transient response, although the numerical analysis yielded some disagreements with experimental results when the applied electric field was low. The disagreements between analytical and experimental results are discussed with a focus on temperature distribution in samples.

The present work deals with the three dimensional axisymmetric problem in a spherical coordinate system. A clamped solid sphere is subjected to heat flux on its plane boundary surface. Heat is generated within the sphere. The attempt made to analyze heat transfer and thermal stresses of solid sphere under steady temperature field. The Legendre's transforms are used for the solution of governing heat conduction equation. The solution of Navier's equation in terms of Goodier's thermoelastic displacement potential and the Boussinesq's harmonic function for spherical co-ordinate system have been used to determine displacement and thermal stresses within solid. The results for temperature change, displacement and stresses have been computed numerically and illustrated graphically.

Exploration adsorption characteristics of zeolite 13X depending on humidity and flow rate in sorption thermal energy storage applications

Gridlike patterns of differing cell density were observed in evenly seeded cell monolayers. Such patterns were obtained in five of six cell lines tested, suggesting widespread occurrence. The mechanism appears to involve small, transient temperature changes related to incubator tray structure. The very short time course of appearance of the patterns implicates attachment rather than growth as the critically affected factor. Impaired adhesion or directed sedimentation resulting from thermally induced microcurrents in the medium are the two most likely mechanisms.

Thermal acclimation following changes from 6 °C to 15 °C and from 15 °C to 25 °C was investigated in the diatom Chaetoceros calcitrans. Cell division rate increased with temperature. Cellular carbon showed a slight decrease with an increase in temperature from 6 °C to 15 °C but showed no further change with an increase to 25 °C. Cells grown at 6 °C had low levels of light-harvesting components and a high carotenoid to chlorophyll a (Chla) ratio due to an increase in abundance of photoprotective pigments. The abundance of light-harvesting pigments increased with temperature and this was mirrored by a decrease in carotenoid: Chla ratio. All pigments showed an immediate change in abundance following each temperature shift. However, changes in photoprotective pigments reached a plateau after 12 h, in contrast to the lightharvesting pigments that took 4 days to become acclimated. Light-saturated rates of photosynthesis were at a minimum at 6 °C and increased twofold with temperature between 6 °C and 25 °C. Light-limited photosynthesis showed little change with temperature. It is suggested that, at low temperatures, the rate of carbon fixation is impaired due to a decrease in the activity of photosynthetic enzymes. This imparts an increase in excitation pressure due to an imbalance between light absorption and utilization. Cells respond to this by decreasing their light-harvesting capacity and increasing their ability to dissipate the excess energy. This fairly rapid regulation may be ecologically advantageous in areas where there are transient temperature changes.

This paper describes a method combining Bayesian optimization (BO) and a lumped-capacitance thermal network model that is effective for speeding up the thermal design optimization of an electronic circuit board layout with transient heating chips. As electronic devices have become smaller and more complex, the importance of thermal design optimization to ensure heat dissipation performance has increased. However, such a thermal design optimization is difficult because various trade-offs associated with packaging and transient temperature changes of heat-generating components must be considered. This study aims to improve the performance of thermal design optimization by artificial intelligence. BO using a Gaussian process was combined with the lumped-capacitance thermal network model, and its performance was verified. As a result, BO successfully found the ideal circuit board layout as well as particle swarm optimization (PSO) and genetic algorithm (GA) could. The CPU time for BO was 1/5 and 1/4 of that for PSO and GA. In addition, BO found a non-intuitive optimal solution in approximately 7 min from 10 million layout patterns. It was estimated that this was 1/1000 of the CPU time required for analyzing all layout patterns.

We measured the principal thermal conductivities and the principal axis angle of a 0.1-mm-thick pyrolytic graphite sheet (PGS), by the integrated multi-temperature probe method. To determine its principal thermal conductivities, a sample is heated using a point heat source places on the sample surface and the transient temperature changes of nine points with radii of r1 = 2.5, r2 = 5.0, and r3 = 7.5 mm on three axes with β= 120° are measured by the integrated multi-temperature probe method. The two measured principal thermal conductivities are λp1 = 746 W/(m·K) and λp2 = 925 W/(m·K). The geometrical mean of the two measured principal thermal conductivities of PGS is λ= (λp1·λp2)1/2 = 831 W/(m·K). The relative errors in this measurement are 7.1% for λp1 and 8.7% for λp2. The calculated anisotropic factor ξ, which is the ratio of λp2 to λp1, is 1.24. The measured data of PGS showed a strong anisotropy of thermal conductivity. This suggests that there is a possibility for PGS to become a standard two-dimensional anisotropic material.

In the processing of titanium alloys, high temperatures at cutting interfaces lead to poor machinability and reduced machining efficiency. High-speed ultrasonic vibration cutting (HUVC) offers an improvement in heat dissipation compared to conventional cutting (CC), yet it loses its cooling advantage as cutting speeds further increase. To optimize efficiency, this study investigated transient cutting temperature variations using experimental measurements and finite element method (FEM) simulations to elucidate the cooling mechanisms in HUVC. An eroding junction thermocouple, along with stringent electromagnetic insulation measures, was employed to capture transient temperature changes with microseconds. The maximum discrepancy between measured and simulated temperatures in CC was found to be 13.8%, validating the feasibility of the FEM method for experimental supplementation and theoretical analysis in HUVC. The results indicated that HUVC reduced cutting temperatures by up to 40.7% compared to CC, with minimal differences in peak temperatures between HUVC and CC at identical cutting speeds. The cooling advantage in HUVC is attributed to temperature declines observed during the interface separation. The maximum temperature reduction ratio increased significantly from 40.9% to 77.1% with the rise in vibration amplitudes. Besides, an increase in tool clearance was found to improve cooling conditions in both CC and HUVC. This study introduced a novel method for ultrasonic temperature measurement in metal cutting, thereby advancing the understanding of cooling mechanisms at cutting interfaces in HUVC. Furthermore, modified process parameters were provided to achieve high-performance HUVC in machining difficult-to-cut alloys.

The basic function of friction clutches is to transfer the torque in the conditions of its smooth engagement without vibrations. Hard working conditions under high thermal and mechanical loads, leading to high temperature in the contact area, intense wear, and instability of the coefficient of friction impose restrictive criteria in the design of friction materials. In this paper, the results of experimental research of the effect of ceramic and intermetallic additives to the copper-based material of the friction disc of the clutch on the thermophysical and frictional properties were presented. Next, these properties were incorporated in the proposed contact 3D numerical model of the clutch to carry out computer simulations of the heating process and subsequent cooling. Based on the obtained experimental data and transient temperature changes of the friction and steel discs, the relations between the powder additives, thermophysical properties of the five friction materials, and coefficients of friction, wear, and temperature reached were discussed. Among these, it was found that when working with the lubrication, the largest values of the coefficient of friction 0.068 and wear were reached when using the 3 wt.% SiC additive.

Daily consumption of food and drink creates rapid temperature changes in the oral cavity. Heat transfer and thermal stress caused by temperature changes in restored teeth may damage the hard and soft tissue components, resulting in restoration failure. This study evaluates the temperature distribution and related thermal stress on mandibular molar teeth restored via three indirect restorations using three-dimensional (3D) finite element analysis (FEA). A 3D finite element model was constructed of a mandibular first molar and included enamel, dentin, pulp, surrounding bone, and indirect class 2 restorations of type 2 dental gold alloy, ceramic, and composite resin. A transient thermal FEA was performed to investigate the temperature distribution and the resulting thermal stress after simulated temperature changes from 36°C to 4 or 60°C for a 2-second time period. The restoration models had similar temperature distributions at 2 seconds in both the thermal conditions. Compared with 60°C exposure, the 4°C condition resulted in thermal stress values of higher magnitudes. At 4ºC, the highest stress value observed was tensile stress (56 to 57 MPa), whereas at 60°C, the highest stress value observed was compressive stress (42 to 43 MPa). These stresses appeared at the cervical region of the lingual enamel. The thermal stress at the restoration surface and resin cement showed decreasing order of magnitude as follows: composite > gold > ceramic, in both thermal conditions. The properties of the restorative materials do not affect temperature distribution at 2 seconds in restored teeth. The pulpal temperature is below the threshold for vital pulp tissue (42ºC). Temperature changes generate maximum thermal stress at the cervical region of the enamel. With the highest thermal expansion coefficient, composite resin restorations exhibit higher stress patterns than ceramic and gold restorations.

Research Article| February 01, 2012 Transient change in groundwater temperature after earthquakes Chi-yuen Wang; Chi-yuen Wang 1Earth & Planetary Science, University of California, Berkeley, California 94720, USA Search for other works by this author on: GSW Google Scholar Michael Manga; Michael Manga 1Earth & Planetary Science, University of California, Berkeley, California 94720, USA Search for other works by this author on: GSW Google Scholar Chung-Ho Wang; Chung-Ho Wang 2Institute of Earth Sciences, Academia Sinica, Nankang, Taipei 11529, Taiwan Search for other works by this author on: GSW Google Scholar Chieh-Hung Chen Chieh-Hung Chen 2Institute of Earth Sciences, Academia Sinica, Nankang, Taipei 11529, Taiwan Search for other works by this author on: GSW Google Scholar Author and Article Information Chi-yuen Wang 1Earth & Planetary Science, University of California, Berkeley, California 94720, USA Michael Manga 1Earth & Planetary Science, University of California, Berkeley, California 94720, USA Chung-Ho Wang 2Institute of Earth Sciences, Academia Sinica, Nankang, Taipei 11529, Taiwan Chieh-Hung Chen 2Institute of Earth Sciences, Academia Sinica, Nankang, Taipei 11529, Taiwan Publisher: Geological Society of America Received: 20 Jun 2011 Revision Received: 25 Aug 2011 Accepted: 12 Sep 2011 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2012 Geological Society of America Geology (2012) 40 (2): 119–122. https://doi.org/10.1130/G32565.1 Article history Received: 20 Jun 2011 Revision Received: 25 Aug 2011 Accepted: 12 Sep 2011 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Chi-yuen Wang, Michael Manga, Chung-Ho Wang, Chieh-Hung Chen; Transient change in groundwater temperature after earthquakes. Geology 2012;; 40 (2): 119–122. doi: https://doi.org/10.1130/G32565.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Postseismic decrease in groundwater temperature was documented on the upper rim of a large alluvial fan near the epicenter of the 1999 Mw 7.5 Chi-Chi earthquake (Taiwan). We use a model of coupled heat transport and groundwater flow, constrained by documented water-level changes, to interpret this change. We show that groundwater temperature is sensitive to earthquake-induced flow and the observed temperature decrease may be explained by increased groundwater discharge due to earthquake-enhanced vertical permeability. The result implies that heat flow near active mountain fronts may be lowered by recurrent earthquakes. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

A start-up behavior of a pulse tube refrigerator is experimentally investigated to gain a better understanding of the basic refrigeration mechanism. Two typical types of pulse tube refrigerators, which are a basic and an orifice pulse tube, are used. The pressure oscillation is introduced suddenly into the pulse tube under the uniform temperature, and the transient changes of gas temperature, wall temperature and heat out at the hot end are obtained as a time history from an onset of the pressure oscillation to an ultimate state that can be obtained after a long time. It is found that after only two cycles from the onset of pressure oscillation, the difference of gas temperature between the cold and the hot ends appears and it reaches to 65% level of the difference at the ultimate state. The heat out becomes stable after several hundreds of seconds. It is also found that the change of temperature at the very beginning of the oscillation is not adiabatic. Significant differences in the start-up behavior between a basic and an orifice pulse tube did not appear.KeywordsWall TemperaturePressure OscillationTemperature OscillationPulse TubeUltimate StateThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Instantaneous and noninvasive temperature measurements are important when laser thermotherapy or welding is performed. A noninvasive nanosecond-resolved magnetic nanoparticle (MNP) temperature measurement system is described in which a transient change in temperature causes an instantaneous change in the magnetic susceptibilities of the MNPs. These transient changes in the magnetic susceptibilities are rapidly recorded using a wideband magnetic measurement system with an upper frequency limit of 0.5 GHz. The Langevin function (the thermodynamic model characterizing the MNP magnetization process) is used to obtain the temperature information. Experiments showed that the MNP DC magnetization temperature-measurement system can detect a 14.4 ns laser pulse at least. This method of measuring temperature is likely to be useful for acquiring the internal temperatures of materials irradiated with lasers, as well as in other areas of research.