No description available.

The study aims to develop an infrared temperature-sensing system by applying to thermal radiation theory. The system consists of an optic unit, a photodetector, and an electronic unit. This system detects thermal radiation at 1310 nm wavelength, the temperature range of the system is 600~4000¢J, rise time 2£gs, spatial resolution 400£gm. The calibration was performed in the temperature low at 1200¢J by using a K-type thermocouple that can gain between temperature and output voltage relations, but beyond the temperature 1200¢J applying to Planck¡¦s law as calculate to predict. In the calibrated temperature range, the measurement error is ¡Ó80¢J for the low temperatures and ¡Ó20¢J for the high temperatures. The system was used to measure temperature variation during Nd:YAG pulse laser welding process. Experiments ware performed with stainless steel plates as specimen radiation by a laser pulse of 7ms duration time and various energy in the rang of 1245~5313mJ. The experimental results show the feasibility of the infrared temperature-sensing system in application of Nd:YAG pulse laser welding process.

Atmospheric noble gases (He, Ne, Ar, Kr, and Xe) dissolved in groundwater are a valuable tool in hydrology. Numerous studies have relied on groundwater recharge temperatures calculated from dissolved noble gas data (noble gas temperatures, NGT) to infer paleoclimate conditions. This research investigated gas dissolution during groundwater recharge and critically examined the use of dissolved noble gas data in groundwater research. A detailed investigation of an agriculturally impacted shallow aquifer allowed comparison of measured water table temperatures (WTT) with calculated NGT. Results suggest that NGT calculated from widely used noble gas interpretive models do reflect measured WTT, supporting the use of dissolved noble gases to deduce recharge temperatures. Samples having dissolved gas concentrations below the equilibrium concentration with respect to atmospheric pressure were attributed to denitrification induced gas stripping in the saturated zone. Modeling indicated that minor degassing (<10% [Delta]Ne) may cause underestimation of groundwater recharge temperature by up to 2 °C. In another study a large dissolved noble gas data set (905 samples) from California was analyzed. Noble gas modeling using the same interpretive models indicates that multiple models may fit measured data within measurement uncertainty, suggesting that goodness-of-fit is not a robust indicator of model appropriateness. A unique aspect of this study was the high Ne and excess air concentrations associated with surficial artificial recharge facilities. A final study examined whether climatic/hydrologic changes occurring over glacial-interglacial time periods could impact the accuracy of NGT used in paleoclimate studies. Numerical modeling experiments estimated WTT sensitivity to changes in: 1) precipitation amount, 2) water table depth, and 3) air temperature. Precipitation and water table depth had a minor impact on WTT (~0.2 °C). In contrast, the impact of air temperature changes on WTT was more pronounced. Results suggest that air temperatures inferred from NGT data may underestimate actual air temperature change since the last glacial maximum by ~1 °C at sites having seasonal snowcover. These results suggest despite uncertainty in the exact physical processes controlling gas dissolution during groundwater recharge, NGT do reflect WTT. However, inferring paleo-air temperatures from NGT are subject to error, especially locations with seasonal snowcover. / text

A multiple-pass cell is developed and applied to enhance the Raman signal from methane-air flames for temperature measurements. Stable operation of the cell was demonstrated and studied in two alignment modes. In the ring mode, the beams are focused into a ring of ~ 3 mm diameter at the center of the cell, and spectra were recorded at low dispersion (0.26 nm/pixel). Temperature is calculated from the ratio of the intensity of Stokes to anti-Stokes signal from nitrogen. Temperature is also inferred from the shapes of the Stokes and anti-Stokes peaks in the spectrum. The uncertainty in the value of flame temperature in these measurements was ±50 K. The signal gain from 100 passes is a factor of 83. Signal to noise ratio (SNR) improved by a factor of 9.3 in room temperature air with an even higher factor in flames. The improvement in SNR depends on the acquisition time and is best for short acquisition times. In the two point mode, multi passing is achieved simultaneously with high spatial resolution as the laser is focused at two small regions separated by ~ 2 mm at the center of the cell. The probe regions are 300 [mu]m × 200 [mu]m. The vast improvement in the spatial resolution is achieved at the cost of a reduced number of passes and signal gain. The two point mode is operated with 25 passes at each point with a signal gain factor of ~20; the SNR gain depends on the data acquisition time. Spectra were recorded at high dispersion (~0.03 nm/pixel). Temperature is inferred from curve fitting to the high resolution Stokes spectrum of nitrogen in methane-air flames. The curve fit is based on very detailed simulation of Raman spectrum of nitrogen. The final model includes the angular dependence of Raman scattering, electrical and mechanical anharmonicity in the polarizability matrix elements, and the presence of a rare isotope of nitrogen in air. The uncertainty in the value of temperature in the least noisy data is ±9 K. The sources of uncertainty in temperature and their contribution to the total uncertainty are also identified. / text

No description available.

Based on a theoretical analysis of the heat transfer process between the human body and its environment, graphs are presented for determining the theoretical skin surface temperatures and sweat rates as a function of the physiological conductance, under certain assumed environmental conditions with regard to air temperature, relative humidity and wind speed. In addition, the development of unique measuring techniques for the direct measurement of the evaporative and radiative heat transfer rates between a human body in a natural working position and its environment as well as the development of a low-cos~ radiometer for the measurement of the emissivity and temperature of human skin are described. The heat loss measuring equipment was installed in the horizontal test section of the climatic chamber of the Human Sciences Laboratory of the Chamber of Mines. Basically the evaporative heat loss measuring system consists of two air-sampling probes, for sampling the air on the upstream and downstream sides of the body , a double circuit heat exchanger, for equalising the dry- bulb temperatures of the two air samples and a differential humidity- measuring system incorporating electrical resistance hygrometero, for measuring the difference in specific humidity between the two air samples. In addition, a steam generator is provided for introducing a known amount of steam at a predetermined rate into the wake of the body. Since the output of the humidity-measuring system is linearly related to the evaporative heat loss rate, the unknown rate of evaporation of moisture from the human body can be determined relatively easily from a knowledge of the respective outputs of the humidity-measuring system due to the moisture evaporation rate of the human body and the known vapour production rate by the steam generator. The direct- measuring instrument for determining the radiation energy exchange rate of a working subject is in the form of a rotating hoop. The inside and outside surfaces of the hoop are lined with thermal radiation-sensing elements, so connected as to measure the net radiation energy exchange between the subject and the surroundings. The hoop integrates over the circular strip formed by the elements and upon rotation, integrates the radiation over the total 4n surface enveloping the subject . While the interposition of a surface between the body and its surroundings must of necessity influence the radiation exchange, the method introduces a small surface only . The significance of the evaporative and radiative heat loss measuring techniques which were successfully used in animate studies, is reflected in the, hitherto unknown, accuracy regarding partial calorimetric studies . The low- cost radiometer for measuring the skin temperature and emissivity is equipped with two non-selective thermal radiation detectors in the form of semi-conductor thermocouples. The one radiation-sensing element faces a built-in reference black body. The other detector, which can be temperature controlled, is used to detect the incoming radiation from the target. The output of the radiation-sensing elements which is sufficiently high to be measured on a recorder without the use of a chopper-amplifier system, can either be measured differentially or the output of the radiation-sensing element facing the target can be measured separately; for the purpose of temperature and emissivity measurements, respectively. The unique facility of being able to vary the temperature of the radiation detector enabled a new method of determining the emissivity of a surface to be developed. As a result, accurate measurements of the emissivities of samples of excised skin could be carried out. An improvement in the response of the radiometer would, however, be necessary for the rapid determination of the emissivity of . living skin by this means. The accuracy with which surface temperatures could be determined by means of the radiometer compared favourably with more sophisticated radiometers. / Thesis (Ph.D.)-University of Natal, Durban, 1974.

Observations of the temperature structure of the stratosphere made by the selective chopper radiometer on the Nimbus 5 satellite are used to analyse the energetics of the sudden warming of January/February 1973. A method of retrieving vertical profiles of zonal Fourier coefficients of temperature from the Fourier coefficients of the measured radiances is described. Some retrievals are compared with conventional observations and quite good agreement is obtained. Comparison of independent estimates of the mean meridional circulation shows that the retrieved temperature and height fields are not sufficiently accurate to give precise values for the zonal mean vertical and meridional velocities. The implication of this result for the energy budget is demonstrated. The sudden warming is analysed first in terms of wave structure and changes in temperature and zonal wind. No evidence for an upward propagating temperature or geopotential disturbance is found. Wave amplifications are observed to occur simultaneously at all levels or to propagate downwards. Largest temperature changes occur in the upper middle stratosphere and maximum zonal flow accelerations in the upper stratosphere. The energy cycle of the lower middle stratosphere is found to be in agreement with observations of previous warmings except in that little increase in eddy energy occurs during the event. A marked baroclinic energy cycle below 10 mb in high latitudes is shown to enhance vertical energy propagation prior to the warming, leading to increased eddy available potential energy between 10 and 2 mb. The variation with latitude of the energetics during the warming is shown to be significant. In the upper stratosphere barotropic conversion from zonal to eddy kinetic energy dominates in mid-latitudes causing deceleration of the zonal flow there first. In high latitudes the deceleration of the zonal flow occurs through the action of the induced mean meridional circulation, while the major source of eddy kinetic energy here is convergence of the vertical eddy energy flux. Examination of the relationship between the latitudinal distributions of the vertical eddy energy flux and the zonal flow reveals that maximum upward propagation of energy is centred con- sistently to the north of the polar night jet until the onset of the warming when coincidence occurs. Some aspects of the observed warming are compared with numerical simulations of sudden warmings. Although the 1973 event is characterised by a wavenumber one disturbance some striking resemblances are found in two numerically simulated wavenumber two type warmings.

This research programme was carried out in order to establish design methods and procedures for thermowells and implement these methods in a computer-based expert system. Thermowells are accessories for the temperature measurement instrumentation and they have to protect the temperature sensor from hazardous environments at high pressures and temperatures. The sensor also needs protection from the flow of the fluid it is immersed in as it can cause the sensor to vibrate and subsequently damage it. Thermowells have to be designed in such a way that they can resist the vibration caused by the flowing fluid, do not collapse due to the surrounding pressure and the thermowell's material has to be compatible with the fluid to avoid corrosion of the thermowell. At the same time they have to transfer the heat of the fluid to the sensor to enable the temperature measurement. A literature review was carried out to establish the available methods and procedures concerning thermowell design. The procedures that deal with the calculation of the natural frequency of thermowells, which is required to ensure the thermowell is not damaged by vibration, were verified using practical vibration analysis techniques. After establishing the appropriate procedures to determine the vibration, pressure, stress and thermal aspects concerning thermowell design, they were implemented in an expert system. The software package KAPPA-PC was used to develop the application. After careful testing and elimination of different errors encountered during the testing phase, an expert system was delivered that carries out the analysis of a given thermowell design and also designs a thermowell for a specified application.

No / An infrared temperature sensor has been used to provide real time quantification of the thermal homogeneity of polymer extrusion. The non-intrusive sensor was located in the barrel of a single screw extruder, positioned such that it provided a measurement of melt temperature in the channel of the metering section of the extruder screw. The rapid response of the technique enabled melt temperature within the extruder screw channel to be monitored in real time, allowing quantification of the thermal stability of the extrusion process. Two polyethylenes were used in experiments with three extruder screw geometries at a range of screw speeds. Data generated by the infrared sensor was found to be highly sensitive to thermal fluctuations relating to the melting performance of the extruder screw. Comparisons made with an intrusive thermocouple grid sensor located in the extruder die suggested that the infrared technique was able to provide a similar level of information without disturbing the process flow. This application on infrared thermometry could prove highly useful for industrial extrusion process monitoring and optimization.

Numerical simulation is used to investigate the accuracy of a direct-contact device for measuring skin-surface temperature. A variation of thermal conductivity of the foam has greater effect on the error rather than a variation of the blood perfusion rate. For a thermal conductivity of zero, an error of 1.5 oC in temperature was identified. For foam pad conductivities of 0.03 and 0.06 W/m-oC, the errors are 0.5 and 0.15 oC. For the transient study, with k=0 W/m-oC, it takes 4,900 seconds for the temperature to reach steady state compared with k=0.03 W/m-oC and k=0.06 W/m-oC where it takes 3,000 seconds. The configuration without the foam and in presence of an air gap between the skin surface and the sensor gives the most uniform temperature profile.