David P. DeWitt

Theory and Practice of Radiation Thermometry

Partial table of contents: FUNDAMENTALS OF RADIOMETRIC TEMPERATURE MEASUREMENT. Physics of Thermal Radiation (D. DeWitt & F. Incropera). Thermal Radiative Properties of Materials (D. DeWitt & J. Richmond). RADIATION THERMOMETERS AND MEASUREMENT METHODS. Wide--Band Radiation Thermometers (R. Leftwich). Fast Radiation Thermometry (A. Cezairliyan, et al.). METHODS FOR CALIBRATION OF RADIATION THERMOMETERS. Calculation of Effective Emissivities of Cavity Sources of Thermal Radiation (R. Bedford). Detector--Based Traceability of Temperature Standards (A. Ono, et al.). APPLICATIONS OF RADIATION THERMOMETRY. Radiation Thermometry in the Steel Industry (F. Milhalow). The Application of Thermography for Building and Industrial Energy Management (P. Mill & G. McIntosh). Index.

Theoretical feasibility of vasodilator-enhanced local tumor heating.

Normal arterioles, in contrast to the abnormal microvasculature of many solid tumors, provide a target for selective drug action which can enhance local heat treatment of the tumors. Measurements of tissue blood flow with radioactive microspheres and estimates of changes in blood flow with thermal clearance methods revealed that vasodilator drugs either decreased or did not alter blood flow in hamster melanoma, rat hepatoma and canine transmissible venereal tumor while increasing perfusion in adjacent normal tissues 2 to 4-fold. Solutions of the bio-heat transfer equation, which take into account such selective effects of vasodilators on blood flow in normal tissues, clearly demonstrate improved selective heating for spheroidal tumors over 2 cm in diameter. In the presence of vasodilator drug effect, steady-state center tumor temperatures of 45-50 degrees C can be achieved by increased power input, while surrounding normal tissues remain below 42 degrees C.

Neonatal Serum Bilirubin from Skin Reflectance

Summary: To provide a noninvasive method for serum bilirubin determination in newborn infants, a reflectometer system was developed using a novel fiber optic arrangement permitting measurement of the light reflected from a small area (3 cm2) of the infants skin. The reflectometer was operated over the spectral region 400–750 nm with a 30-sec scan time. The reflectometer consisted of a monochomatic light source, fiber optic probe, detector, and data acquisition systemSpectral reflectance measurements were performed on the blanched and unblanched skin on the backs of 56 Caucasian newborn infants. Examples of the spectra and corresponding serum bilirubin values of 30 of the infants are presented, illustrating that near 460 nm, the spectral reflectance of the skin decreases with increasing serum bilirubin concentrations. It was also observed that the individualities in epidermal hemoglobin concentration affected the skin reflectance spectra. For this reason the statistical analysis was limited to inclusion of only reflectance spectra of blanched skin.The multispectral analysis of the data was based upon statistical regression analysis investigating the predictability of serum bilirubin level from reflectance spectra. The spectrum between 400 and 740 nm was divided into 5-nm intervals (71 discrete bands). First order linear, multiple linear, and polynomial nonlinear regressions were performed on the spectral reflectance values at each of the intervals with respect to serum bilirubin level. The coefficients of determination (R2 values) are summarized.Because an R2 of only 0.783 was observed at 450 nm, scatter diagrams of serum bilirubin concentration versus spectral skin reflectance at a given wavelength were studied. These indicated that a logarithmic transformation of the data might yield improved results. The double natural logarithm was taken of the 71 discrete spectral reflectance values and a polynomial nonlinear regression was performed with respect to serum bilirubin concentration. The best results of this regression analysis were obtained for a combination of five wavelengths yielding an R2 value of 0.931.The ability to predict serum bilirubin concentration from skin reflectance using this relationship was tested using the original observations. The 95% prediction limit for this empirical relationship was shown to be ± 2 mg/100 ml.Speculation: Spectral reflectance measurements on the newborn skin provide a noninvasive screening method for neonatal jaundice and may also be useful in assessing the efficacy of phototherapy and the potential for kernicterus.

Experimental and analytical study of heat radiation in a diesel engine

An experimental study was conducted of the heat radiation in a single-cylinder direct injection 14 iota engine. The engine was operated at speeds ranging from 1000 to 2100 RPM and a variety of loads. The radiation was measured using a specially designed fiber optics probe operating on the two-color principle. The probe was located in the head at two different locations: in one location it faced the piston bowl and in the other it faced the piston crown. The data obtained from the probe was processed to deduce the apparent radiation temperature and soot volume concentration as a function of crank angle. The resultant profiles of radiation temperature and of the soot volume concentrations were compared with the predictions of a zonal heat radiation model imbedded in a detailed two-zone thermodynamic cycle code.

Multiband Radiometer For Field Research

To develop the full potential of multispectral data acquired from satellites, increased knowledge and understanding of the spectral characteristics of specific earth features is required. Knowledge of the relationships between the spectral characteristics and important parameters of earth surface features can best be obtained by carefully controlled studies over areas, fields, or plots where complete data describing the condition of targets is attainable and where frequent, timely spectral measurements can be obtained. The currently available instrumentation systems are either inadequate or too costly to obtain these data. Additionally, there is a critical need for standardized acquisition and calibration procedures to ensure the validity and comparability of data.

Inferring temperature from optical radiation measurements

The methodology for inferring temperature from optical radiation exitent from an opaque surface is described. Beginning with the measurement equation, the output of the radiation thermometer is related to radiant flux reaching the detector. Characteristics of blackbody radiators are reviewed, and the effects of surface emissivity, reflected irradiances, and the atmosphere are presented. Applications to a reheat furnace and a direct-fired process heater illustrate the practical importance of these effects and point out the need for a firm understanding of the physics of thermal radiation to properly interpret radiation thermometer observations.

Modeling of solvent evaporation effects for hot plate baking of photoresist

A heat transfer model for hotplate baking is combined with a mass transfer model for solvent diffusion to predict the major effects of photoresist prebaking for photolithography. Solvent diffusivity as a function of solvent concentration and temperature is determined experimentally. The results of the model are a complete time-temperature history of the wafer, final solvent distribution within the resist film, and final resist thickness.

Determination of Serum Bilirubin by Skin Reflectance: Effect of Pigmentation

Summary: A noninvasive optical technique by which serum bilirubin can be estimated from skin spectral reflectance measurements has been further investigated. The original work on 30 healthy, full-term white infants and an independent study on 14 white and 30 black infants demonstrate that the method has potential not only for clinical use, but also for the study of the transport of bilirubin to, from and within the skin. The objectives of the present study are to evaluate the method on a larger sample population with special attention to natural skin pigmentation effects and the development of a physical model of the tissue to explain the relationship between serum bilirubin concentration and skin reflectance.Reflectance spectra (380–800 nm) and concurrent serum bilirubin measurements were taken on a sample population of 58 white and 45 full-term black infants (1–3 days of age). Multiple linear regression analysis, comprised of six wavelengths gave a correlation coefficient, r = 0.831 for the white infant group. For the black infant group, a five wavelength analysis provided r = 0.877 with the standard error of estimate being ±1.46 ing/100 ml for both groups.The model for establishing a physical basis for the relationship shows that a transformed, normalized Kubelka-Monk function *** (460, 510, 420) is linearly related to serum bilirubin concentration. This function is determined from the spectral reflectance values at three wavelengths, 420, 460, and 510 nm. The wavelength combination is such that effects due to hemoglobin and melanin pigments are minimized. Regression analysis showed that r = 0.778 and r = 0.865 for the white and black infant groups, respectively, with standard error of estimates being ±1.4 mg/100 ml for both groups.Routine determinations of total serum bilirubin by laboratory methods have standard errors of estimate ranging from ±1 to 1.5 mg/100 ml. Thus, the method herein described shows that the relationship between skin reflectance and serum bilirubin in full-term infants is close to the acceptable limits for clinical use. Furthermore, this work shows that skin pigmentation does not obscure this relationship.Speculation: Because skin pigmentation does not obscure the relationship between serum bilirubin and spectral reflectance, the latter is clinically useful for jaundice screening for all neonates. It may also be helpful in monitoring phototherapy of jaundiced infants although the spectral considerations may be extremely complex in these cases. Once such relationships are determined, however, skin reflectance may also offer a measure of the risks of kernicterus.

Applications of radiation thermometry

This book contains 12 papers. Some of the titles are: Radiation thermometry--the measurement problem; Radiation thermometry--status and trends; A review of temperature measurement in the steel reheat furnace; Recent advances and research activities in Japan: and Fiber-Optic thermometry.

Optimizing Oven Radiant Energy Use

This paper reports on research efforts to reduce oven energy use while maintaining the quality of foods that are baked or roasted. The baking process and the role of radiant energy in the conventional electric oven were investigated. This led to the development of a more energy efficient oven system that optimizes the use of radiant energy by using two electric elements controlled independently to present more radiant power to the top of prod ucts being baked, utensils that readily absorb radiant energy, and oven walls that reflect infrared radiation to the product being baked. Energy savings of 75 percent or more are possible for baking many foods.