Showing papers in "No source information available in 1975"

Fluidic partial pressure sensor

Abstract: A fluidic partial pressure sensor for measuring the partial pressure of a s constituent in a mixture relative to a reference gas. The pressure drop output of a fluidic bridge concentration sensor is connected to the aspirated input of a fluidic aspirator which is operated in its sonic or saturated region. By virtue thereof, the vacuum created in the aspirated input is directly proportional to the ambient pressure at the output of the aspirator. Since the ratio of the bridge pressure drop is therefore made constant, the output pressure of the bridge sensor is thereby directly proportional to the partial pressure of the gas constituent of interest.

Prediction of turbulent flow in curved pipes

Abstract: A finite-difference procedure is employed to predict the development of turbulent flow in curved pipes. The turbulence model used involves the solution of two differential equations, one for the kinetic energy of the turbulence and the other for its dissipation rate. The predicted total-velocity contours for the developing flow in a 180° bend are compared with the experimental data. Predictions of fully developed velocity profiles for long helically wound pipes are also presented and compared with experimental measurements.

Increase of the melt viscosity of polycaproamide by chromium(III) ions

Abstract: The melt viscosity of polycaprolactam can be enhanced by incorporation of chromium (III) ions into the resin. As a possible interpretation of this phenomenon, formation of a mixed complex is suggested by X-ray diffraction, infrared and uv. absorption spectroscopic studies. By comparison with a model compound, it was found that the carbonyl oxygen and the water occurring in the polymer appear to be the coordination centres of chromium (III) ions. The hypothetical composition of the mixed complex is [Cr(COamide)n(H2O)6−n]3+ where 2 ⩽ n ⩽ 6.

On the eddy structure of hurricanes

Abstract: Given the general conditions present in a mature hurricane, this paper seeks to show by observational and theoretical means that the circulation regime within a hurricane, beyond a certain radius, must be of the eddy type rather than axisymmetric. This is done by first pointing out, following recent results of Starr, that mean radial circulations cannot transport angular momentum across surfaces of constant mean values of this quantity. A diagram is constructed showing such momentum surfaces obtained from data for a mean hurricane, and it is demonstrated that there must be a flux of momentum across these closed surfaces. This flux, therefore, can only be produced by an eddy type circulation regime.

Dewatering of dredged materials by evaporation.

Abstract: During recent years many of the bottom sediments dredged from the harbours and channels located near heavily populated industrial areas of the United States have been judged polluted by the Environmental Protection Agency. As a consequence, open water disposal of these materials is severely restricted, and they are often placed within diked containment areas. However, since such dredgings usually have a high water content and contain substantial amounts of clay-like and/or organic materials, the effectiveness of the associated landfill operations and the utilisation of these materials are strongly affected by their dewatering characteristics. Evaporation has been identified as an effective and economical means for accomplishing such dewatering, and the quantitative results of several field and laboratory studies are evaluated herein and placed in perspective. Pursuant to obtaining the soil-water potential of several typical dredgings, three series of laboratory tests were conducted to study: (a) the rate of water loss and the effect of mixing, (b) the influence of layer thickness and surface area on the rate of water loss, and (c) the effect of lime treatment on the rate of water loss. Two series of field evaporation tests were performed to investigate the effects of sample thickness, lime-treatment, and drainage conditions on the evaporative losses of water and time dependent gains in strength under the given climatic conditions. The results of these studies are supplemented with those of several other studies conducted by others but not reported in the literature.

Laminar fluidic multiplier.

Abstract: A fluidic multiplier which comprises a proportional fluidic amplifier operated in the laminar region. The gain of the amplifier is proportional to the power jet pressure, thereby providing an output signal which is the product of the input signal and the supply pressure. A preconditioning and buffering circuit is also disclosed for linearizing and isolating the multiplier from other circuitry.

Ion etching of amorphous and semicrystalline fibres

Abstract: Ion etching of amorphous and semicrystalline fibres produces structures which can be observed in either the transmission electron microscope or the scanning electron microscope. The structures so produced have previously been identified as resulting from the etching process (artifacts), or as representing characteristics of the material, or both. The artifacts can be eliminated or minimized by rotating the sample during irradiation, using a low angle of incidence, and ensuring that the temperature of the sample surface remains low. When such precautions are used, amorphous fibres and semicrystalline fibres which arenot oriented remain featureless after ion etching. Oriented semicrystalline fibres, however, develop a striated structure which is oriented perpendicular to the stretch direction. The spacing between the striations is in the range of 500 to 5000 a, an order of magnitude larger than the characteristic lamellar spacing in the materials. These transverse structural features reflect characteristic features of drawn fibres; but the relation between these features and the lamellar spacing is unclear.

Enteric viruses and drinking water supplies.

Abstract: The purpose of this paper is to review briefly the status of knowledge concerning the enteric virus problem with respect to drinking water, to assess its current public health significance and to define the priorities for approaches to its further evaluation. So much information on waterborne enteric viruses has accumulated over the years that it is impossible to provide here a comprehensive review of all aspects of this subject. Instead, only those aspects of particular relevance to drinking water will be considered in detail. Comprehensive coverage of this subject is available in a number of recent reviews.1-4 The viruses of major concern in water are those that infect the alimentary tract of man and are excreted in the feces by infected persons. These are the so-called enteric viruses, and they are likely to be present in waters recently contaminated with sewage (Table 1). Because of the continuous use of oral polio vaccine, the most prevalent enteric viruses in sewage are often vaccine-strain polioviruses. It should be kept in mind that enteric viruses are obligate intracellular parasites of man and, in the case of reoviruses, lower mammals as well. Therefore, they cannot multiply in sewage or water, and their numbers in aquatic environments will decrease because of removal and inactivation process. Enteric virus concentrations in domestic raw sewage cannot be precisely established because of limitations in virusdetection methods and because of the variability

Effect of fungal degradation on mechanical properties of cellophane

Abstract: Changes in dynamic mechanical properties of cellophane films due either to fungal attack or to hydrochloric acid hydrolysis have been measured. It appears that damage caused by cellulase enzymes that are released from a fungal overgrowth is localized in noncrystalline regions. These effects include a substantial reduction in elastic modulus, a reduction in temperature at which relaxation processes involving chain segmental mobility occur, and a broadening of loss tangent peaks due to segmental mobility and to rotations of methylol groups. Comparing results obtained from cellulase hydrolysis with those obtained from acid hydrolysis, it is clear that enryme attack proceeds by a characteristic and selective process. Implications regarding the embrittlement often seen to accompany biodegradation are discussed.