Finite size effects near the onset of the oscillatory instability

A system of two complex Ginzburg - Landau equations is considered that applies at the onset of the oscillatory instability in spatial domains whose size is large (but finite) in one direction; the dependent variables are the slowly modulated complex amplitudes of two counterpropagating wavetrains. In order to obtain a well posed problem, four boundary conditions must be imposed at the boundaries. Two of them were already known, and the other two are first derived in this paper. In the generic case when the group velocity is of order unity, the resulting problem has terms that are not of the same order of magnitude. This fact allows us to consider two distinguished limits and to derive two associated (simpler) sub-models, that are briefly discussed. Our results predict quite a rich variety of complex dynamics that is due to both the modulational instability and finite size effects

Implicit solutions with consistent additive and multiplicative components

Use of multiple-point-constraint

The French Atlantic littoral and the Massif Armoricain, part 1

The author has identified the following significant results. For interpretation of Isle of Jersey imagery, two types of taxons were defined according to their variability in time. On the whole, taxons with a similar spectral signature were opposed to those with strongly varying spectral signature. The taxon types were low diachronic variations and strong diachronic variation. Imagery interpretation was restricted to the landward part of the Fromentine area, including the sand beaches which were often difficult to spectrally separate from the barren coastal dunes in the southern part of Noirmoutier Island as well as along the Breton marsh. From 1972 to 1976, sandbanks reduced in area. Two high river discharge images showed over a two year period an identical outline for the Bilho bank to seaward, whereas upstream, the bank has receeded in the same time to a line joining Paimboeuf to Montoir. The Brillantes bank has receeded at both ends, partly due to dredging operations in the access channel to Donges harbor

Quantitative Interpretation of Quasar Microlensing Light Curves

We develop a general method for analyzing the light curves of microlensed quasars and apply it to the OGLE light curves of the four-image lens Q2237+0305. We simultaneously estimate the effective source velocity, the average stellar mass, the stellar mass function, and the size and structure of the quasar accretion disk. The light curves imply an effective source plane velocity of 10200 km/s ) < 39600 km/s (68% confidence). Given an independent estimate for the source velocity, found by combining estimates for the peculiar velocity of the lens galaxy with its measured stellar velocity dispersion, we obtain a mean stellar mass of =0.037h^2 solar masses (0.0059h^2 /Msun < 0.20h^2). We were unable to distinguish a Salpeter mass function from one in which all stars had the same mass, but we do find a strong lower bound of 50% on the fraction of the surface mass density represented by the microlenses. Our models favor a standard thin accretion disk model as the source structure over a simple Gaussian source. For a face-on, thin disk radiating as a black body with temperature profile T_s ~ R^(-3/4), the radius r_s where the temperature matches the filter pass band (2000 Angstroms or T_s(r_s)=70000K) is (1.4 x 10^15)/h cm < r_s < (4.5 x 10^15)/h cm. The flux predicted by the disk model agrees with the observed flux of the quasar, so non-thermal or optically thin emission processes are not required. From the disk structure we estimate a black hole mass of M_BH = (1.1_(-0.7)^(+1.4) x 10^9) h^(-3/2) (L/L_E)^(-1/2) solar masses, consistent with the mass estimated under the assumption that the quasar is radiating at the Eddington luminosity (L/L_E=1).Comment: 39 pages, 11 figures (some only in jpeg format), submitted to Ap

Synthesis and Physical Characterization of Solid-State Materials.

Two quantitative X-ray powder diffraction methods were used to analyze Phosphogypsum, a currently underutilized solid by-product of phosphoric acid production. Three kinds of synthetic mixtures were prepared to reflect the variable composition of phosphogypsum: AG (anhydrite and gypsum), QCD (quartz, calcite, and dolomite), and AGQCD. Compositions derived from the Whole Pattern fitting method for the binary and ternary mixtures agreed reasonably well with known values, with residuals \rm\langle R\sp2\rangle = 0.10 for eleven AG samples, and \rm\langle R\sp2\rangle = 0.018 for thirteen QCD samples. However, in the five-component mixtures, overlap of anhydrite, dolomite and gypsum peaks prevented quantitation. Compositions derived from the Matrix Flushing method were generally superior, with \rm\langle R\sp2\rangle = 0.009 for eleven AG mixtures, \rm\langle R\sp2\rangle = 0.0004 for thirteen QCD mixtures, and \rm\langle R\sp2\rangle = 0.0197 for nine AGQCD mixtures. The most notable exception in the determination of AG mixtures with 0-10% gypsum. The measured compositions were distorted in favor of gypsum, apparently due to the affinity of gypsum for water. Two single crystal structures, one organometallic and the other inorganic, were determined. \rm\lbrack (phen)\sb2Cu\rbrack \sp{+}(hfacac)\sp{-} crystallizes in triclinic space group P1 with: a = 10.284(0)A, b = 11.685(0)A, c = 12.519(0)A and \rm\alpha = 114.97(0)\sp\circ ,\ \beta = 90.77(0)\sp\circ ,\ \chi = 105.78(0)\sp\circ .\ Ba\sb{1-x}K\sb{x}BiO\sb3,\ x = 0.419(0), a superconductor with \rm Tc = 29.5\sp\circ K. It crystallizes in cubic space group with Pm3m symmetry and a cell constant of a = 4.2948(0)A. The diffraction-quality crystal of \rm Ba\sb{1-x}K\sb{x}BiO\sb3 was synthesized by electrosynthesis in a molten KOH flux at \rm 225\sp\circ C. The synthesis required ultra-pure KOH (99.99%), \rm Ba(OH)\sb2{\cdot}8H\sb2O (99.8%), \rm Bi\sb2O\sb3 (99.9998%), and a cover gas of water-saturated ultra-pure Ar. The melt composition was based on weight ratios K/Ba = 17.2 and K/Bi = 12.5. The electrode deposition potential was 0.677 volts, starting current $\rm I\cong 20\ \mu A.$ Every attempt was made to maintain a current density of less than \rm 0.5mA/cm\sp2, to ensure slow crystal growth

Development of an induction motor condition monitoring test rig And fault detection strategies

Includes bibliographical references.This thesis sets out to develop an induction motor condition monitoring test rig to experimentally simulate the common faults associated with induction motors and to develop strategies for detecting these faults that employ signal processing techniques. Literature on basic concepts of induction motors and inverter drives, the phenomena of common faults associated with induction motors, the condition monitoring systems were intensively reviewed