Apparent Temperature Change Research Articles

Monitoring changes in hydric properties of treated stone material with conservation products by time-sequential IR thermography

A methodological approach for a semi-quantitative non-destructive testing (NDT) of the effects on hydric properties after the application of different conservation treatments (commercial ethylsilicate and siloxane compounds with consolidant, water repellent or consolidant + water repellent properties) is presented in this study. The NDT used for this purpose is a simplified method of time-sequential infrared thermography (IRT) on stone (granite and marble, treated and untreated) from the Roman theatre of Merida (Spain), which was listed by UNESCO as World Heritage Site in 1993.As water evaporation modifies temperature intensely, IRT enables monitoring the response of the stone samples during water absorption-evaporation processes. The comparative analysis between treated and non-treated specimens was performed by calculating the rate of surface apparent temperature change (ΔoC/h) value. The capillary rising test, monitored by IRT, clearly showed a different response of the samples treated with water-repellent treatments, proving their efficiency. Samples treated with organosilicic compounds showed a large and rapid drop in apparent surface temperature, indicating that water accesses rapidly.Results from the evaporation test also show this difference. The surface apparent temperature increased immediately in samples with water-repellent treatments, in which water does not enter inside stone, but remains on the surface. Samples with ethyl silicate, again, show a greater difference with respect to untreated samples, taking longer to recover surface apparent temperature, because the water is retained inside the stone for longer.This study proved simplified time-sequential IRT as a reliable technique for assessing the efficacy of conservation treatments applied to stone materials in laboratory.

Interleaved water and fat MR thermometry for monitoring high intensity focused ultrasound ablation of bone lesions.

PurposeTo demonstrate that interleaved MR thermometry can monitor temperature in water and fat with adequate temporal resolution. This is relevant for high intensity focused uUltrasounds (HIFU) treatment of bone lesions, which are often found near aqueous tissues, as muscle, or embedded in adipose tissues, as subcutaneous fat and bone marrow.MethodsProton resonance frequency shift (PRFS)‐based thermometry scans and T1‐based 2D variable flip angle (2D‐VFA) thermometry scans were acquired alternatingly over time. Temperature in water was monitored using PRFS thermometry, and in fat by 2D‐VFA thermometry with slice profile effect correction. The feasibility of interleaved water/fat temperature monitoring was studied ex vivo in porcine bone during MR‐HIFU sonication. Precision and stability of measurements in vivo were evaluated in a healthy volunteer under non‐heating conditions.ResultsThe method allowed observing temperature change over time in muscle and fat, including bone marrow, during MR‐HIFU sonication, with a temporal resolution of 6.1 s. In vivo, the apparent temperature change was stable on the time scale of the experiment: In 7 min the systematic drift was <0.042°C/min in muscle (PRFS after drift correction) and <0.096°C/min in bone marrow (2D‐VFA). The SD of the temperature change averaged over time was 0.98°C (PRFS) and 2.7°C (2D‐VFA).ConclusionsInterleaved MR thermometry allows temperature measurements in water and fat with a temporal resolution high enough for monitoring HIFU ablation. Specifically, combined fat and water thermometry provides uninterrupted information on temperature changes in tissue close to the bone cortex.

Field drift correction of proton resonance frequency shift temperature mapping with multichannel fast alternating nonselective free induction decay readouts.

PurposeTo demonstrate that proton resonance frequency shift MR thermometry (PRFS‐MRT) acquisition with nonselective free induction decay (FID), combined with coil sensitivity profiles, allows spatially resolved B 0 drift‐corrected thermometry.MethodsPhantom experiments were performed at 1.5T and 3T. Acquisition of PRFS‐MRT and FID were performed during MR‐guided high‐intensity focused ultrasound heating. The phase of the FIDs was used to estimate the change in angular frequency δωdrift per coil element. Two correction methods were investigated: (1) using the average δωdrift over all coil elements (0th‐order) and (2) using coil sensitivity profiles for spatially resolved correction. Optical probes were used for independent temperature verification. In‐vivo feasibility of the methods was evaluated in the leg of 1 healthy volunteer at 1.5T.ResultsIn 30 minutes, B 0 drift led to an apparent temperature change of up to –18°C and –98°C at 1.5T and 3T, respectively. In the sonicated area, both corrections had a median error of 0.19°C at 1.5T and –0.54°C at 3T. At 1.5T, the measured median error with respect to the optical probe was –1.28°C with the 0th‐order correction and improved to 0.43°C with the spatially resolved correction. In vivo, without correction the spatiotemporal median of the apparent temperature was at –4.3°C and interquartile range (IQR) of 9.31°C. The 0th‐order correction had a median of 0.75°C and IQR of 0.96°C. The spatially resolved method had the lowest median at 0.33°C and IQR of 0.80°C.ConclusionFID phase information from individual receive coil elements allows spatially resolved B 0 drift correction in PRFS‐based MRT.

A coupled thermo-poroelastic analysis of wellbore stability for formations with anisotropic strengths

The temperature difference between the drilling fluid and formation will lead to an apparent temperature change around the borehole and tend to cause borehole instability problems in oil and gas drilling process. The wellbore stability models used in thinly laminated rock formations integrate the in situ stresses, pore pressure, well trajectory, and rock strength parameters to improve the wellbore stability; however, a limited amount of research has focused on the factor of formation temperature and its difference between drilling mud. Hence, a wellbore stability model is introduced based on the stress transformations and the Mohr-Coulomb failure criteria, which incorporate the rock strength anisotropy and the temperature difference between formation and drilling mud. The wellbore instability problems of anisotropic strength formation are analyzed using this model. The results show that the shear failure of rock matrix mainly occurs at two symmetric locations around the borehole and the size of failure region decreases with the inclination angle, in contrast, the shear slip failure of weak plane occurs at four locations around the borehole. The mud density required for isotropic strength should be selected as the required mud density to keep the wellbore stable if the inclination angle less than a certain value, and it almost keeps a constant with the inclination angle changes. On the contrary, the mud density required for slippage along the plane of weakness should be selected when the inclination angle larger than this value, and it is increasing with the inclination angle. Positive temperature difference will aggravate the wellbore instability, the larger the temperature difference the bigger the mud density is required.

The effect of evaporative cooling on climatic parameters in a stable for sows

The aim of this study was to find out the effect of indirect evaporative cooling on microclimatic parameters in a stable for sows. A high-pressure system was used for cooling, the nozzles sprayed water into the outside air before its entering into the building. Temperature-humidity index during cooling was higher by 0.9 than in the section without cooling (P &amp;lt; 0.001). Due to low indoor air flow velocity (below 0.18 m/s), a change in apparent temperature by the Comprehensive Climate Index (CCI) was only 1.94&amp;deg;C. It would be possible to provide markedly better cooling effectiveness by increasing the air velocity up to 2 m/s, which may improve the CCI by 19.8% and thus to achieve better environmental conditions for housed sows. The efficiency of evaluated evaporative cooling system was moderate because the nozzles were placed outdoors and only part of humidified and cooled air was drawn into the building through inlet openings, and also because the indoor air-flow velocity was low.

Radiative precursors driven by converging blast waves in noble gases

A detailed study of the radiative precursor that develops ahead of converging blast waves in gas-filled cylindrical liner z-pinch experiments is presented. The experiment is capable of magnetically driving 20 km s−1 blast waves through gases of densities of the order 10−5 g cm−3 (see Burdiak et al. [High Energy Density Phys. 9(1), 52–62 (2013)] for a thorough description). Data were collected for Ne, Ar, and Xe gas-fills. The geometry of the setup allows a determination of the plasma parameters both in the precursor and across the shock, along a nominally uniform line of sight that is perpendicular to the propagation of the shock waves. Radiation from the shock was able to excite NeI, ArII, and XeII/XeIII precursor spectral features. It is shown that the combination of interferometry and optical spectroscopy data is inconsistent with upstream plasmas being in LTE. Specifically, electron density gradients do not correspond to any apparent temperature change in the emission spectra. Experimental data are compared to 1D radiation hydrodynamics HELIOS-CR simulations and to PrismSPECT atomic physics calculations to assist in a physical interpretation of the observations. We show that upstream plasma is likely in the process of being radiatively heated and that the emission from a small percentage of ionised atoms within a cool background plasma dominates the emission spectra. Experiments were carried out on the MAGPIE and COBRA pulsed-power facilities at Imperial College London and Cornell University, respectively.

Borehole Stability in High-Temperature Formations

In oil and gas drilling or geothermal well drilling, the temperature difference between the drilling fluid and formation will lead to an apparent temperature change around the borehole, which will influence the stress state around the borehole and tend to cause borehole instability in high geothermal gradient formations. The thermal effect is usually not considered as a factor in most of the conventional borehole stability models. In this research, in order to solve the borehole instability in high-temperature formations, a calculation model of the temperature field around the borehole during drilling is established. The effects of drilling fluid circulation, drilling fluid density, and mud displacement on the temperature field are analyzed. Besides these effects, the effect of temperature change on the stress around the borehole is analyzed based on thermoelasticity theory. In addition, the relationships between temperature and strength of four types of rocks are respectively established based on experimental results, and thermal expansion coefficients are also tested. On this basis, a borehole stability model is established considering thermal effects and the effect of temperature change on borehole stability is also analyzed. The results show that the fracture pressure and collapse pressure will both increase as the temperature of borehole rises, and vice versa. The fracture pressure is more sensitive to temperature. Temperature has different effects on collapse pressures due to different lithological characters; however, the variation of fracture pressure is unrelated to lithology. The research results can provide a reference for the design of drilling fluid density in high-temperature wells.

Change in apparent temperature is associated with incidence of ischemic stroke

Change in apparent temperature is associated with incidence of ischemic stroke

A comprehensive index for assessing environmental stress in animals1

Numerous models and indices exist that attempt to characterize the effect of environmental factors on the comfort of animals and humans. Heat and cold indices have been utilized to adjust ambient temperature (Ta) for the effects of relative humidity (RH) or wind speed (WS) or both for the purposes of obtaining a "feels-like" or apparent temperature. However, no model has been found that incorporates adjustments for RH, WS, and radiation (RAD) over conditions that encompass hot and cold environmental conditions. The objective of this study was to develop a comprehensive climate index (CCI) that has application under a wide range of environmental conditions and provides an adjustment to Ta for RH, WS, and RAD. Environmental data were compiled from 9 separate summer periods in which heat stress events occurred and from 6 different winter periods to develop and validate the CCI. The RH adjustment is derived from an exponential relationship between Ta and RH with temperature being adjusted up or down from an RH value of 30%. At 45 degrees C, the temperature adjustment for increasing RH from 30 to 100% equals approximately 16 degrees C, whereas at -30 degrees C temperature adjustments due to increasing RH from 30 to 100% equal approximately -3.0 degrees C, with greater RH values contributing to a reduced apparent temperature under cold conditions. The relationship between WS and temperature adjustments was also determined to be exponential with a logarithmic adjustment to define appropriate declines in apparent temperature as WS increases. With this index, slower WS results in the greatest change in apparent temperature per unit of WS regardless of whether hot or cold conditions exist. As WS increases, the change in apparent temperature per unit of WS becomes less. Based on existing windchill and heat indices, the effect of WS on apparent temperature is sufficiently similar to allow one equation to be utilized under hot and cold conditions. The RAD component was separated into direct solar radiation and ground surface radiation. Both of these were found to have a linear relationship with Ta. This index will be useful for further development of biological response functions, which are associated with energy exchange, and improving decision-making processes, which are weather-dependent. In addition, the defined thresholds can serve as management and environmental mitigation guidelines to protect and ensure animal comfort.

Estimating the mortality effect of the July 2006 California heat wave

Objective As a result of the California heat wave in July 2006, county coroners reported that the high temperatures during that period caused approximately 147 deaths. However, heat wave-related deaths are likely to be underreported due to a lack of a clear case definition and the multi-factorial nature of heat-related mortality. Public health policy suggests a need for a careful assessment of mortality following a heat wave. In addition, it is useful to provide a comparison of the mortality impact per degree change during heat waves versus high temperatures observed during non-heat wave periods. Design Daily data were collected for mortality, weather and ozone in seven California counties impacted by the July 2006 heat wave. The association between apparent temperature and daily mortality was assessed using a Poisson regression model and combined across counties in a meta-analysis. These results were then used to estimate the increases in the number of deaths during the heat wave. Results Our analysis indicated that during the July heat wave, there was a 9% (95% CI=1.6, 16.3) increase in daily mortality per 10° Fahrenheit (F) change in apparent temperature for all counties combined. This estimate is almost 3 times larger than the effect estimated for the full warm season of May–September, during the non-heat wave years. Our estimates also determined that actual mortality during the July 2006 heat wave was 2–3 times greater than the coroner estimates. Conclusion This multi-county analysis provides additional evidence that the attributable risk of mortality following a heat wave may be underestimated by examining only direct heat-related deaths. In addition, we have found that the mortality effect per °F is several times higher than that reported during non-heat wave periods.

Temperature mapping considerations in the breast with line scan echo planar spectroscopic imaging

A line-scan echo planar spectroscopic imaging (LSEPSI) sequence was used to serially acquire spectra from 4,096 voxels every 6.4 s throughout the breasts of nine female subjects in vivo. Data from the serial acquisitions were analyzed to determine the potential of the technique to characterize temperature changes using either the water frequency alone or the water-methylene frequency difference. Fluctuations of the apparent temperature change under these conditions of no heating were smallest using the water-methylene frequency difference, most probably due to a substantial reduction of motion effects both within and without the imaged plane. The approach offers considerable advantages over other methods for temperature change monitoring in the breast with magnetic resonance but suffers from some limitations, including the unavailability of lipid and water resonances in some voxels as well as a surprisingly large distribution of water-methylene frequency differences, which may preclude absolute temperature measurement.

Urbanization Effect on the Observed Change in Mean Monthly Temperatures between 1951–1980 and 1971–2000 in Korea

Gridded temperature data are necessary to run ecological models at regional scales for climate impact studies and have been generated by spatially interpolating measured values at synoptic stations. Because there are few synoptic stations with long-term records in rural areas in Korea, data from urban stations have been used for this purpose. Due to the overlapping of the rapid urbanization-industrialization period with the global warming era in Korea, climate data from these urbanized areas might be contaminated with urban heat island effect. This study was conducted to differentiate urbanization and regional climate change effects on apparent temperature change. Monthly averages of daily minimum, maximum, and mean temperature at 14 synoptic stations were prepared for 1951-1980 (past normal) and 1971-2000 (current normal) periods, respectively.Differences in two temperature normals were regressed to the logarithm of the population increase at 14 corresponding cities from 1966 to 1985. The regression equations were used to determine potential effects of urbanization and to extract the net contribution of regional climate change to the apparent temperature change. According to the model calculation, urbanization effect was common in all months except April. Up to 0.5° warming of nighttime temperature was induced by urbanization in the current normal period compared with the past normal period. There was little effect of regional climate change on local warming in the warm season (May through November). The cool season was warmed mainly by regionally increased daytime temperature. The results could be used to remove urbanization effects embedded in raw data, helping restore unbiased rural temperature trends in South Korea.

Apparent Temperature Patterns Superposed on Thermal Infrared Images and Their Removal

A thermal infrared image is a visualized image of the thermal energy radiated from an object. Thermal radiation energy is dependent on the absolute temperature and the effective emissivity of an object, so that a thermal infrared image does not give the temperature distribution of an object but, rather, is a superimposed image of, so to speak, the temperature pattern and the emissivity pattern. In other words, a emissivity pattern is an apparent temperature pattern superimposed on a true temperature pattern. However, this paper points out that a thermal infrared image obtained with a sensor having an instantaneously large field of view, like a remotely sensed image, has additionally a third pattern due to the size of the field of view superimposed and that this appears as an apparent temperature change on the thermal infrared image. Moreover, the paper stresses the fact that in order to obtain correct information on temperature, it is necessary to remove these patterns and, at the same time, points out that these can be removed if effective use is made of visible, multispectral images.

Thick film thermometers with predictable R- T characteristics and very low magnetoresistance below 1 K

A new type of RuO 2-based thick film resistor has been investigated for use as a thermometer in the millikelvin temperature range. The resistance versus temperature behaviour between 25 and 800 mK can be described with an accuracy of better than 0.5% by the relation found for conduction by variable-range hopping: R( T) = R 0 exp[( T 0/ T) α ], with α = 0.345. This relation was found to be valid down to at least 6 mK with an accuracy of a few per cent. The low temperature resistance behaviour can be predicted within 2% starting from the room temperature resistance value. The thermometers show a small negative magnetoresistance effect from which the apparent temperature change exceeds 2% only at temperatures below 0.1 K and in fields of more than 5 T. No dependence of the magnetoresistance effect on the orientation of the field has been found.

Evaporation and Energy Transfer for a Partially Molten, Laser‐Heated Sapphire Filament

Molten regions were formed on 0.025‐cm‐diameter sapphire filaments that were heated from one side with a continuouswave CO2 laser beam in a low‐pressure flow reactor. As the laser intensity was increased, the liquid/solid interface moved from the laser‐heated edge to the opposite edge of the filament, the apparent temperature measured in the molten region with an optical pyrometer increased from 1470 ± 25 to 2040 ± 30 K, and the filament evaporation rate increased by a factor of 1.6. This change in apparent temperature resulted from an increase in the spectral emittance with the liquid layer thickness. The change in evaporation rate resulted from a 1.09 times larger evaporating area, a 1.24 ± 0.09 times larger evaporation coefficient, and a 10 ± 5 K larger average temperature when the filament cross section was completely liquid than when liquid first formed on the solid filament. Optical and energy‐transfer properties of sapphire and liquid Al2O3 were calculated from optical pyrometry, energy‐balance measurements, and spectral absorption coefficient data for sapphire. At the melting temperature, the total emittance is approximately 0.051 and 0.31 ± 0.03 for the solid sapphire and liquid aluminum oxide filaments, respectively. The thermal accommodation coefficient for Ar atoms is 0.53 ± 0.07 on the solid and approximately unity on the liquid. The spectral absorption coefficient, kλ, at the optical pyrometer wavelength (0.665 μm) is 0.1 ± 0.04 cm−1 for the solid and 12 ± 12 cm−1 for the liquid. This value of kλ for solid sapphire at the melting point is 12 times that of pure, void‐free material and reflects the influence of impurities and small voids in the sapphire filaments that were used.

テンポラル熱赤外画像からの見かけ上の温度変化パターンの除去

テンポラル熱赤外画像からの見かけ上の温度変化パターンの除去

Determination of the surface temperature of water during evaporation studies. a comparison of thermistor with infrared radiometer measurements

In this investigation the temperature of a water surface was measured by two techniques, one utilizing a commercial infrared radiometer and the other, thermistor probes. Both methods were shown to be satisfactory for following changes in surface temperature during evaporation studies; however, the radiometer used was less sensitive to changes in temperature than the thermistors, being limited to changes in temperature of 0.1°C. or greater. The radiometer does have the advantage of measuring the temperature of a much thinner layer of water than the thermistor, 0.1 mm. as compared to 2 or 3 mm. It also responds more rapidly to changes in water temperature than the thermistor and can be operated at some distance from the water surface. It was shown during this study that the presence of a monomolecular film will not significantly alter the emissivity of a water surface, within the limit of sensitivity of the radiometer. Any change in apparent temperature detected by the radiometer when a monolayer is spread at the interface must, therefore, be due to changes in the real temperature of the water surface. Such changes could result from the monolayer's influence on the rate of evaporation or on movement of surface water.