No abstract

Data are given on the accuracy of the balanced thermocouple and filter radiometer as a standard ultraviolet dosage intensity meter. The erythema produced by the radiometrically measured amount of heterogeneous ultraviolet radiation is compared with that produced by a measured amount of homogeneous radiation of the emission line of mercury, at 297 m/x, which is used as a standard. This requires the determination of the ultraviolet spectral energy curve, and the total ultraviolet of wave lengths less than and including 313 m^t, of the source under test. An exact knowledge of the spectral erythemic response of the skin is also required (RP433) Sources differing markedly in ultraviolet spectral energy distribution were investigated, including as extremes the sun, and the so-called "cold quartz" mercury vapor lamp. * Figures in parentheses here and throughout the text indicate references given in the bibliography at the end of this paper. cobientz, stair] UltraViolet Filter Radiometry

The spectral erythemic reaction of three persons exposed to equal amounts of homogeneous ultraviolet radiation, of various wave lengths, is described. The source of radiation was a standard vertical quartz mercury vapor lamp which has a series of intense conveniently spaced emission lines, extending from 248 to 365 m/i. These emission lines were separated by passage through the spectrometer exit slit, the jaws of which were dusted with anthracene, .which, by fluorescence, indicated the accuracy of the isolation of the line under investigation. The erythemal reaction and the radiometric measurements were made on the spectral line directly back of the exit slit. In the region of 250 mn the spectral erythemic reaction was supplemented by exposures to the heterogeneous radiation from a mercury vapor lamp having a high selective emission in the resonance line at 253.7 m/i. Data are given on the reciprocity of intensity and time of exposure, and also on the relative spectral erythemic reaction in the range of wave lengths extending from 245 to 315 mju.

A piezohydraulic microjet design and experimental results are presented to demonstrate broadband active flow control for applications on various aircraft structures including impinging jets, rotor blades, cavity bays, etc. The microjet actuator includes a piezoelectric stack actuator and hydraulic circuit that is used to throttle a 400 μm diameter microjet using hydraulic amplification of the piezoelectric stack actuator. This system is shown to provide broadband pulsed flow actuation up to 800 Hz. Unsteady pressure measurements of the microjet's exit flow are coupled with high-speed phase imagery using micro-Schlieren techniques to quantify the flow field. These results are compared with in situ stack actuator displacements using strain gauge measurements.

In the present paper a description is given of the calibration of a selective photochemical, ultra-violet dosage intensity meter against a balanced thermocouple and filter radiometer, used as a standard. Data are given of the ultra-violet intensities of solar radiation in various localities at various elevations at various stations in Europe and upon the ocean.The measurements show a high ultra-violet reflection from clean fresh snow. The ultra-violet intensities over the ocean are not conspicuously higher than at a sea level, dust-free station on land at the same latitude and the same season of the year.