Showing papers by "Cairo University published in 1980"

The Influence of Liquid Film Thickness on Airblast Atomization

Abstract: The influence of initial liquid film thickness on mean drop size and drop-size distribution was examined using two specially designed airblast atomizers. Both were constructed to produce a flat liquid sheet across the centerline of a two-dimensional air duct with the liquid sheet exposed on both sides to high velocity air. In one case a thin film of uniform thickness was produced by injecting the liquid through a porous plate located just upstream of the atomizing edge. The film thickness, t, was then measured by a needle contact device. In the second design the fuel entered the air stream through a thin slot whose height could be adjusted accurately to vary and control the initial film thickness. Drop sizes were measured by the well-established light-scattering technique. From analysis of the processes involved, and from correlation of the experimental data, it was found that high values of liquid viscosity and liquid flow rate result in thicker films. It was also observed that thinner liquid films produce better atomization, according to the relationship, SMD ∝ t0.38 .

A scheme for the automatic generation of triangular finite elements

Abstract: This paper describes a method for the automatic triangulation of arbitrary multilateral plane domains. In addition, the method can be used in connection with that suggested by Zienkiewicz and Phillips4 for the subdivision of curved-boundary domains. The method can be described as general fully automatic and computer oriented. A Fortran computer program has been prepared by the author. Output can be of interactive, graphical or alphanumerical form. The program has been applied to a number of cases. The resulting triangulations are always satisfactory, even when vigorous changes of mesh sizes are encountered.

Macaroni supplemented with lupin and defatted soybean flours

Abstract: Macaroni was produced from wheat flour blended with 0, 2,4, and 6% of the high protein, low starch flours of lupin and defatted soybean. Increased lupin or defatted soybean flours increased volume and weight of macaroni. Macaroni cooking quality decreased with increasing level of soybean flour but increased with increasing level of lupin flour. In addition, the natural amber color of the lupin imparted a desirable color to macaroni whereas increasing the soybean flour level imparted an undesirable grayish color.

Self-similar explosion waves of variable energy at the front

Abstract: A set of self-similar solutions for blast waves associated with the deposition of variable energy at the front is presented As a consequence of self-similarity, the results are applicable when the ambient atmosphere into which the wave front propagates is at a negligibly low pressure and temperature Besides the class of (1) blast waves associated with energy gain that covers a regime bounded on one side by the well-known solution for adiabatic strong explosion waves (ASE) and, on the other side, by the solution for waves having the Chapman–Jouguet condition established immediately behind the front, included within the scope of our analysis are two others: (2) blast waves associated with energy loss that occupy a regime between the ASE solution and the case of infinite density ratio across the front, and (3) a non-unique class of solutions for blast waves associated with energy deposition that may have either locally sonic or supersonic flow immediately behind the front, extending over the regime between the waves headed by the Chapman-Jouguet detonation and the case of infinite rate of energy deposition Specific results for a number of representative cases are expressed in terms of integral curves on the phase plane of reduced blast wave co-ordinates, as well as in the form of particle velocity, temperature, density, and pressure profiles across the flow field

Serum immunoglobulins in patients with chronic tonsillitis.

Abstract: In this work, the serum immunoglobulin (IgG, IgA, IgM and IgD) levels were determined in ten patients with chronic tonsillitis The serum immunoglobulins were estimated before and two months after tonsillectomy, using the radial immuno-diffusion method Ten normal individuals with intact tonsils were chosen as a control group The patients had elevated serum levels of IgG and IgA These high levels may be due to repeated antigenic stimulation The IgM and IgD were not significantly higher than in the normal controls The serum IgG level did decrease significantly following tonsillectomy; the other three immunoglobulins were reduced, but insignificantly The fall in immunoglobulins may be due to a reduction in the antigenic load, to the removal of immunoglobulin-producing tissue, or to alteration in the oropharyngeal pathogenic bacteria Tonsillectomy does not seem to compromise immunological integrity or the immunoglobulin-producting apparatus Estimations of the serum immunoglobulin, or simply of IgA, may help us to select those candidates for adeno-tonsillectomy who will have a good prognosis, or at least to exclude those with an underlying sub-clinical immunodeficiency disease

Mechanism of thermal hysteresis in reversible transformation of K2SO4

Abstract: The reversible phase transformation of potassium sulphate is studied. Differential thermal analysis, dilatometric and dielectric measurements show the occurrence of a reversible phase transition at 571 °C for K2SO4 with heat of transformation H = 2.3 kcal/mol and activation energy E = −215 kcal/mol. The thermal hysteresis in this reversible transformation is examined, the magnitude of the temperature hysteresis does not exceed 5 K. An acceptable agreement is observed between the measured values of the transition temperature obtained by the three different techniques. The dilatometric analysis shows that this transition is accompanied by thermal expansion with a relative thermal expansion coefficient of 6 × 10−3. The mechanism and physical basis for the phenomenon of thermal hysteresis observed in the temperature of the phase transition are proposed and discussed thermodynamically on the assumption that there is a potential barrier between the atomic arrangements of any two phases. Es wird die reversible Phasentransformation von Kaliumsulphat untersucht. Thermische Differentialanalyse, Dilatometrie und dielektrische Messungen zeigen das Auftreten eines reversiblen Phasenubergangs bei 571 °C fur K2SO4 mit einer Ubergangswarme H = 2,3 kcal/mol und einer Aktivierungsenergie E = 215 kcal/mol. Die thermische Hysterese bei dieser reversiblen Transformation wird untersucht, und die Grose der Temperaturhysterese ubersteigt nicht 5 K. Eine annehmbare Ubereinstimmung zwischen den gemessenen Werten der Ubergangstemperatur, die mit drei verschiedenen Methoden bestimmt wurden, wird beobachtet. Die dilatometrische Analyse zeigt, das dieser Ubergang von thermischer Ausdehnung mit einem relativen thermischen Ausdehnungskoeffizienten von 6 × 10−3 verknupft ist. Ein Mechanismus und die physikalische Basis fur das Phanomen der bei der Temperatur des Phasenubergangs auftretenden thermischen Hysterese werden vorgeschlagen und unter der Annahme, das eine Potentialbarriere zwischen den Atomanordnungen in beiden Phasen existiert, thermodynamisch diskutiert.

Mutagenic and carcinogenic effects of pesticides.

Abstract: A discussion of the mutagenic and carcinogenic effects of various classes of commonly used pesticides. Classes discussed include halogenated hydrocarbons organophosphorus insecticides, and certain herbicides and fungicides. Halogenated hydrocarbons were found generally hazardous, causing sterility and displaying marginal or definite carcinogenic activity. Several organophosphorus insecticides have been shown to be mutagens; some have been shown to be carcinogens. Both the herbicide impurity tetrachlorodibenzodioxin, TCDD, and maleic hydrazide have been shown to be carcinogenic in mice and rats. The role of DNA as a critical target for carcinogenic activity is also discussed.

Unsaponifiable Matter of Six Pollens Collected by Honeybees in Egypt

Abstract: SummaryGas-liquid chromatography (GLC) was used for the identification and quantitative analysis of unsaponifiables of samples from the 6 major pollen sources in the Nile Delta region of Egypt (families Leguminosae, Cruciferae, Compositae, Linaceae, Rutaceae). The composition of the sterol compounds was much simpler than that of the hydrocarbons; usually 6 to 8 sterols were detected and 13 to 16 hydrocarbons. Cholesterol, stigmasterol and β-sitosterol were the major sterol components, β-sitosterol being predominant. Results indicated that unsaponifiables, taken as a group, may provide a key for the identification of pollen sources.

Linear analysis of the light curves of eclipsing variables

Abstract: In this paper, general model analysis of the form ∑c i φ i (θ) for the fractional loss of lightf(ϑ) exhibited by a close binary system will be considered in the sense of the least-squares criterion. A general recursive method will be established for constructing the normal equations for the most useful functionsφ i (θ), and an economical storage of the method on a digital computer, with its computational steps, will also be given. Moreover, a full recursive computational algorithm for the least-squares approximation will also be established. By means of this algorithm, all the solution vectors, the variance for different orders of fit and the corresponding variance-covariance matrix could be computed once and for all and, moreover, recursively. The economical storage of the algorithm and its computational steps will be given. Finally, some of the practical difficulties encountered in the application of the least-squares criterion will be analysed, and some techniques for detecting and controlling these difficulties are also given. Numerical examples on the Algol system using a Fourier cosine series of the form ∑c i cos [(j - 1) π θ/η] will be given for illustration.