An all-digital ΣΔ--frequency discriminator of arbitrary order

In this paper, we propose an all-digital frequency synthesizer architecture, based on an all-digital ΣΔ-frequency discriminator. The new all-digital synthesizer is compared to previously published work. The architecture of the ΣΔ-frequency discriminator is verified using behavioral simulation

Laser spectroscopy of the mercury-zinc excimer.

Extensive and previously unknown fluorescence and excitation spectra of the HgZn excimer have been observed and correlated with a potential energy (PE) diagram drawn and labelled according to Hund\u27s case (c). The spectra were excited in a Hg-Zn mixture contained in a quartz vapour cell by successive pulses from two dye lasers using the pump-and-probe method, and were recorded using techniques of time-resolved fluorescence spectroscopy. The reservoir states, which became populated by the pump pulse, were found to be the A1, AO\sp- and AO\sp+ states. The fluorescence band at 4750 A, which has a 6$\mu$s lifetime and was first observed by Eden\sp1, was recognized as due to bound-continuum decays from the A1 and AO\sp+ states to the XO\sp+ ground state, and its time-evolution was recorded at various cell temperatures. Subsequent absorption of the probe pulse resulted in the excitation of several higher-lying states which were identified as the CO\sp+, E1, F1 and EO\sp- states. Several excitation spectra were recorded and assigned to CO\sp+ $\gets$ AO\sp+, E1 $\gets$ AO\sp-, E1 $\gets$ AO\sp+, F1 $\gets$ AO\sp+, EO\sp- $\gets$ A1 and EO\sp- $\gets$ AO\sp- transitions. UV fluorescence bands, which were observed centered at 2500 A, 2270 A and 2230 A, consisted of well-resolved Condon internal diffraction patterns, and were correlated with appropriate upper-state vibrational wave functions. They were attributed to bound-continuum transitions from the CO\sp+, E1 and F1 states to the XO\sp+ ground state, respectively. Bound-bound fluorescence bands were observed at 4288 A, 4122 A, 4236 A and 4637 A, and were identified as arising from F1 $\to$ AO\sp+, EO\sp- $\to$ Al, EO\sp- $\to$ AO\sp- and EO\sp- $\to$ BO\sp- transitions, respectively. A predissociation effect, which gave rise to Hg 4916 A emission, was also observed and interpreted. Analysis of the experimental data yielded vibrational constants, relative energies and relative internuclear separations of the PE minima for the various states. There is good agreement between the measured transition energies and the values estimated from the PE diagram. Source: Dissertation Abstracts International, Volume: 50-03, Section: B, page: 0996. Thesis (Ph.D.)--University of Windsor (Canada), 1989

A Kinetic Analysis of the Iodination of Pyruvic Acid and Pyruvate Esters

In the present work the relative rates of iodination of pyruvic acid and ethyl and methyl pyruvate have been compared at 25.0° C. These studies allow the determination of the respective free energies of activation for these processes. Measurements have also been carried out at various temperatures to determine the enthalpies and entropies of activation for the spontaneous and base catalysed iodinations of these pyruvate systems. The present thesis also includes a comparison of the solvent deuterium isotope effects associated with the spontaneous rate of iodination of pyruvic acid and the alkyl pyruvates. Also, the catalytic rate coefficients associated with the basic components of various buffers have been determined for the iodination of methyl pyruvate. These values together with the spontaneous rate of iodination allow the determination of the Brønsted coefficient, S, associated with this process. From these kinetic results, we hope to delineate the mechanism of catalysis for the enolization of pyruvate systems: by distinguishing between intra- and intermolecular catalysed pathways and by accessing the relative importance of carbon-hydrogen bond breaking, and oxygen-hydrogen bond making in the transition states of these enolization processes

The Effects of Growth Regulators and Apical Bud Removal on Growth, Flowering, and Corms Production of Two Gladiolus Varieties

Gladiolus is commonly propagated from corms. The multiplication rate of corms is low and to increase the propagation rate, we examined a combination of apical bud removal and the application of growth regulators. The experiments were conducted in two varieties, ‘Rose Supreme’ and ‘White Prosperity’, and over two seasons. The apical buds on the planting corms were either removed or left intact before the same corms were soaked in a suspension with either 100 ppm of benzyladenine (BA), 100 ppm of gibberellic acid (GA3), or pure water. The results showed that apical bud removal increased the number of corms and shoots. GA3 had limited the effect on corm and shoot production, but instead resulted in increased total leaf area and leaf weight per shoot. BA, on the other hand, increased the number of corms and shoots. Overall, the removal of the apical bud plus application of BA increased the number of corms and shoots but reduced the average corm diameter and leaf weight per shoot. This was clearer in ‘Rose Supreme’ than in ‘White Prosperity’. To maximize flower production for the coming season, farmers need to produce a high number of planting corms, but they also need to balance this with a sufficient corm size and the production of flowers of good quality. The application of growth regulators in combination with apical bud removal should be fine-tuned to avoid a situation that leads to the production of too many small or too few large corms.publishedVersio

EFFECT OF SUBSURFACE DRAINAGE SYSTEM DESIGN ON THE SOIL AND WATER MANAGEMENT

A field experiment was carried out to study the effect of drain depth on the drainage water quality and flax productivity. The flax crop was planted during winter season. The field experiment was conducted at the Bahteem Research Station, Qaliubiya Governorate, from November 2015 till April 2016. Two design systems were selected, the first was conventional drainage system (CDS), with drain depth 1.5 m, the second was modified drainage system (MDS), three lateral drain lines were installed to main drain directly. The depth of the lateral drain was (0.90 - 1.0) m.   The obtained results revealed that the salinity of the average soil profile decreased after the second irrigation onward. The soil salinity percentages of (MDS) decreased by (47, 30 and 9.5) for (2nd, 3rd and 4th) irrigation, respectively. On the other hand, soil salinity percentages of (CDS) decreased by (40, 32 and 9) for (2nd, 3rd and 4th) irrigation, respectively. The chloride percentages for average soil profile of (MDS) decreased by (77, 82 and 54) for (2nd, 3rd and 4th) irrigation, respectively. On the other hand, the chloride percentages of (CDS) decreased by (70, 75 and 35) for (2nd, 3rd and 4th) irrigation, respectively. The EC values of drainage water of (MDS) decreased from first irrigation onwards. The EC percentages of drainage water salinity of (MDS) decreased by (10.6, 18.2 and 22.7) for (2nd, 3rd and 4th) irrigation, respectively. On the other hand, the EC percentages of drainage water salinity of (CDS) decreased by (6.3, 5.6 and 24.6) for (2nd, 3rd and 4th) irrigation, respectively. The chloride percentages of drainage water  salinity of (MDS) decreased by (22.6, 43 and 14.2) for (2nd, 3rd and 4th) irrigation, respectively. On the other hand, the chloride percentages of (CDS) decreased by (14.7, 32 and 16.4) for (2nd, 3rd and 4th) irrigation, respectively. The piezometer reading showed that the water table levels reaching the soil surface upon irrigation reached low level before the next irrigation. The average values of water table after first irrigation were (14.5, 11 cm) for (MDS) and (29.5, 24 cm) for (CDS) for (L/4, L/2 distance from drain line), respectively. Also the results indicated that the water table level continue decreasing for both systems before 2nd and 3rd irrigation. The results recorded were (91, 82 cm), (140.5, 132 cm) before 2nd irrigation; (75.5, 60 cm), (133.5, 125 cm) before 3rd irrigation for (L/4, L/2 distance from drain line) for both systems (MDS) and (CDS), respectively. On the other hand data showed that the water table was higher after 2nd irrigation on ward. The results recorded were (16.5, 10 cm), (33.5, 25 cm) after 2nd irrigation; (7.5, 3 cm), (28, 21 cm) after 3rd irrigation for (L/4, L/2 distance from drain line) for both systems (MDS) and (CDS) respectively. So (MDS) produced drainage water with higher quality and lower salts concentration than the (CDS). At the end of the season the flax productivity was 3.5 ton/fed for both systems. It can be recommended to be used (MDS) with shallow drain depth