Numerical simulation of annular phased arrays for anatomicallybased models using the FDTD method

Annular phase arrays (APAs) of aperture and dipole antennas used for hyperthermia are simulated in three dimensions by using the finite-difference time-domain (FDTD) method. A 17363 cell, 1.31 cm resolution, anatomically based model of the human torso surrounded by a bolus of deionized water is used for calculations of specific absorption rates (SARs). Test runs on the calculation of fields in the water-filled interaction space and with homogeneous circular- and elliptical-cylinder phantoms correlate well with the experimental data in the literature, lending support to the accuracy of the FDTD method for near-field exposure conditions. Results are given for APAs using different sizes of aperture and dipole antennas and for a subannular array to obtain higher SARs in the liver. It is concluded that, because of its flexibility, the proposed procedure may be useful for a variety of realistic radiofrequency applicators for hyperthermia and other biomedical applications     

Thyroid hormones in diabetic ketoacidosis before and after therapy

Fifteen IDDM patients were evaluated for thyroid hormone abnormalities before and after control of diabetes mellitus/ketoacidosis. Blood sugar mean +/- SEM mg/dl on admission was 430 +/- 20.3 and after therapy fasting and post prandial blood sugar values were 120 +/- 14.5 and 150 +/- 20.2 respectively. GHb mean +/- SEM % on admission was 15.2 +/- 0.36. Serum T3 mean +/- SEM ng/dl of 0.36 +/- 0.04 was in hypothyroid range and rT3 mean +/- SEM ng/ml 0.40 +/- 0.6 was significantly raised (P < 0.001) before therapy. After metabolic control both T3 and rT3 became normal. T4 concentration mean +/- SEM meg/dl of 5.5 +/- 0.7 was well within normal range before therapy and rose to mean +/- SEM mcg/dl 8.8 +/- 0.5 after therapy (P < 0.01). TSH response to TRH was blunted in uncontrolled state. It is concluded that peripheral changes in T3, T4 and rT3 (low T3, high rT3 and low or normal T4) occurred in uncontrolled diabetic state during ketoacidosis. TSH response to TRH was blunted due to suppression of hypothalamic pituitary thyroid axis which takes more than a week for complete recovery.     

UV reactor flow visualization and mixing quantification using three-dimensional laser-induced fluorescence

Three-dimensional laser-induced fluorescence (3DLIF) was applied to visualize and quantitatively analyze mixing in a lab-scale UV reactor consisting of one lamp sleeve placed perpendicular to flow. The recirculation zone and the von Karman vortex shedding that commonly occur in flows around bluff bodies were successfully visualized. Multiple flow paths were analyzed by injecting the dye at various heights with respect to the lamp sleeve. A major difference in these pathways was the amount of dye that traveled close to the sleeve, i.e., a zone of higher residence time and higher UV exposure. Paths away from the center height had higher velocities and hence minimal influence by the presence of sleeve. Approach length was also characterized in order to increase the probability of microbes entering the region around the UV lamp. The 3DLIF technique developed in this study is expected to provide new insight on UV dose delivery useful for the design and optimization of UV reactors.     

Effects of unequal reactivity of functional groups on gelation phenomena in polyurethane systems

A model to describe the effect of unequal reactivity on curing of a diisocyanate with water, polyol and a diol was developed. The model predicts whether a given initial composition would gel or not and the fractional conversions of functional groups at the gel point. It has been shown that the relative speeds of reaction of water and hydroxyl groups can be used to classify water's behaviour as that of a (i) nonreactive diluent (ii) monofunctional blocking agent and (iii) chain extender capable of connecting branch points.     

Formulas for calculating the calorific value of coal and coal chars: Development,tests, and uses

A new formula for calculating the calorific value of coal from its ultimate analysis has been obtained by regression analysis of a data bank consisting of data on 775 samples of U.S. coals of all ranks. It yielded zero average difference between observed and calculated values and a standard deviation of 129 Btu/lb (300 kJ/kg). Neither average difference nor standard deviation varied much with rank of the coal. The Dulong, Mott-Spooner, Boie, and Grummel-Davies formulae were also tested with the data but gave substantially poorer results. The new formula has been substantiated with data from other laboratories and with data on chars. The distribution of variance, attributable to variability of mineral matter, variability of coal organic matter not related to rank, and variance of laboratory determinations was estimated. Use of the formula to monitor performance of a laboratory is illustrated, as is modification to obtain maximum precision in heat balance calculations on a coal conversion process.     

Blend analysis by conventional infra-red spectrophotometry. Part 1-polyester/cotton blends

This paper deals with the blend analysis of polyester/cotton blends using conventional i.r. spectrophotometry. More accurate prediction of blend composition is possible by using the peak areas at the 725cm^-1 band and logarithmic ratios of 3385cm^-1/725cm^-1 and 3385cm^-1/1715cm^-1 than by using the 1715cm^-1 peak area as is the normal practice. The results are then found to be less affected by sample inhomogeneity and variations in sampling accuracy.     

Acrylonitrile copolymers using cobalt acetylacetonate-triethylaluminum initiator system

Summary The reactivity ratios of styrene and acrylonitrile were computed from the ¹³C-NMR spectra of copolymers prepared using cobalt acetylacetonate-triethylaluminum initiator system and compared with a free radical initiator such as AIBN. The results indicate that polymerization using the former has pronounced free radical characteristics.     

Mutual coupling and sidelobe tapers in phase-only antenna synthesisfor linear and planar arrays

A method of obtaining the lowest possible peak sidelobe levels, given a specified sidelobe envelope, by phase-only variation of the generator phases is presented. A generalization of earlier work by the authors, this technique involves the optimization of a piecewise differentiable objective function using the method of steepest descent to obtain desired generator phases, given prescribed excitation magnitudes. The method has been applied to both linear and planar arrays of radiators, with single-mode mutual coupling effects included to provide realistic data. Values for the various array performance indices are presented, and results indicate that introduction of sidelobe taper improves the array gain while raising the peak sidelobe level somewhat. Inclusion of mutual coupling effects alters the required phases for optimum patterns but does not significantly affect the performance indices of the array