Marangoni convection in a liquid layer under the simultaneous action of a transverse magnetic field and rotation

Asymptotic stability characteristics with respect to the onset of Marangoni convection in a liquid layer under the simultaneous action of a large transverse magnetic field and a large rate of rotation are investigated. In certain parameter ranges there is a decrease in critical Marangoni number for increasing magnetic field and rotation depending on the coupling between interfacial perturbations and rotation.     

IR-spectroscopy of ionosphere from stratospheric balloons

The radiation spectra of the ionosphere in the 4–5 μm region have been determined from stratospheric balloons by means of the specially elaborated method of the registration of angular and spectral distribution of the radiation. The radiation bands of 4.4 μm and 4.8 μm which have 0.1–0.2 erg cm^?2 sr^?1s^?1. brightness obtained in two flights, are identified with the vibration-rotation transitions of the ion NO⁺ (0 - 1) and the molecules N¹⁴N¹⁵ (0 - 1) and CO (0 - 1) and (3 - 2) from altitudes between 120 and 500 km.     

Vertical profiles of halocarbons in the stratosphere

Stratospheric air samples collected between 10 and 35 km altitude my means of a cryogenic sampler were analyzed by gaschromatography. Thus vertical profiles of source gases for halogen radicals were derived, such as CCl₄, CCl₃F, CCl₂F₂, CClF₃, CF₄, C₂F₃Cl₃, C₂F₄Cl₂, C₂F₅Cl, C₂F₆, CH₃Cl, CH₃CCl₃, CHF₂Cl, CH₃Br, CBrF₃, and CBrCl₂F. Systematic discrepancies between measured and modelled halocarbon profiles point to deficiencies of present one- and two-dimensional models. Measurements of fully halogenated hydrocarbons provide a tool for systematically studying these deficiencies and thus improving the models.     

ELF radio signals produced in the auroral ionosphere by non-linear demodulation of signals from high-power amplitude-modulated transmitters

ELF and VLF radio signals were recorded in the afternoon to early morning (local time) between 24 March and 4 April 1979, in Northern Scandinavia. Apart from signals of natural origin, timing signals, i.e. six pips of equal duration of 105 ± 8 ms, at 1 kHz ± 0.5 Hz, were observed on the hour UT. Such signals only occur on days of relatively high geomagnetic activity during enhanced auroral electrojet activity. They are believed to be generated by non-linear demodulation (self-detection) of signals from two or more amplitude modulated transmitters in the USSR, operating at 173, 200, 236, 263 and 657 kHz. The simplest explanation for the observations is provided by the three transmitters operating at 173 kHz.     

Gravitational influence on binary alloy melt equilibria

Micro- and macrosegregation, the nonuniform redistribution of solute during solidification, are common to both casting and welding, processes of fundamental importance in materials engineering. In multicomponent crystal growth where solid/liquid density differences are appreciable gravity-induced separation can lead to significant spatial variations in resulting ingot composition. In fact, this phenomenon is also operative in liquid/liquid systems such as monotectic alloys exhibiting a liquid miscibility gap, where buoyancy-driven flows can result in a sometimes unwanted separation of phases upon cooling through the miscibility dome.     

Knowledge Acquisition for ATE Diagnosis

An applied intelligence program for ATE fault diagnosis shows promise as an effective method to reduce mean time to repair (MTTR). The types of knowledge required by an intelligent diagnostic for VLSI test systems, the resources needed to derive that knowledge, the approach implemented to organize it, and the final form of the knowledge representations which resulted from our work are discussed in this paper.     

Application of remote sensing techniques in mineral resources survey — a case study pertaining to Singhbhum Shear Zone,Bihar, India

Geological analysis and evaluation of digitally processed and enhanced LANDSAT MSS data products for three test areas of Singhbhum Shear Zone, India has led to certain significant results regarding optimisation and utility of such techniques for geological studies and obtaining additional/new information regarding lithology and structure. Three band-to-band ratio images are found to give best results. Lithologic formations could be subdivided into a number of units. The Westward and southeastward extension of the shear zone could be delineated thereby indicating scope of mineralisation in these parts.     

Thermal and thermosolutal convective effects in bridgman solidification: Effect of orientation relative to gravity

A concentrated binary system (Ge-Si) and a dilute one (Ge-Ga) have been solidified at 1 g, in a new vertical Bridgman furnace where radial thermal gradients have been minimized. Very different solutal boundary layer extents (δ_Ge-Si = 3 cm, δ_Ge-Ga = 2.5 mm) obtained for both systems solidified in the same thermal conditions are explained by simple analytical hydrodynamic models. It is demonstrated that :1. The convective transport of Ga in the Ge-Ga system is due to the unavoidable residual horizontal thermal gradients associated with discontinuity of thermal properties at the solid-liquid interface.2. The larger boundary layer extent observed for Ge-Si and the corresponding pure diffusive transport is the result of the stabilizing effect of the longitudinal solutal gradient in this system.Thus, in the case of dilute systems, convective effects can only be cancelled through a reduction of the gravity level. On the opposite, pure diffusive solute transport can be achieved in the vertical configuration a 1 g in the case of concentrated systems where a stabilizing solutal effect is operating.