Correlation of LANDSAT data with surface and subsurface information—a synergistic,quantitative approach to oil exploration in Gujarat,India

An attempt has been made to correlate the optical-density values derived from LANDSAT imagery of a part of the oil field areas of Gujarat, India, with all the available surface and subsurface information by employing a mathematical model specifically developed for this purpose. An excellent two-dimensional linear correlation exists between optical-density values of tonal anomaly areas and gravity and magnetic values. A high correlation coefficient factor was also obtained when a multiple correlation of different parameters with optical density was carried out. This study has proved that such a synergistic, quantitative approach is much more useful in oil exploration than simple visual interpretation of remotely sensed data.     

Elemental micro-segregation characteristic of fiber laser welded Hastelloy C-276 sheet

The elemental micro-segregation characteristic within the weld zone for ytterbium fiber laser welded Hastelloy C-276 sheet was investigated. The analysis of segregation ratio and equilibrium distribution coefficient of elements, determined through EDS data, indicate the reduction in micro-segregation of elements compared with the previous reported literatures for laser welded Hastelloy C-276. High melting efficiency of ytterbium fiber laser, reduction in the amount of linear heat input, and high cooling rate of the mushy zone lead to the reduction in micro-segregation. The melting efficiency of ytterbium fiber laser for welding of Hastelloy C-276 of 64% is higher than that (48%) of conventional welding methods. High melting efficiency leads to the reduction in the linear heat input required for welding. Hence, in the present investigation, the same was found to substantially reduce as compared to the previous reported literature. The cooling rate from liquidus temperature to solidus temperature at the weld centerline was found to be in the order of 10³ °C/s. Cellular dendritic substructure that constituted for lower micro-segregation was formed at the weld centerline.     

Pyrolysis of petroleum asphaltenes from different geological origins and use of methylnaphthalenes and methylphenanthrenes as maturity indicators for asphaltenes

Asphaltenes separated from two different crude oils from upper Assam, India, having different geological origins, viz. DK (eocene) and JN (oligocene–miocene) were pyrolysed at 600 °C and the products were analysed by gas chromatography–mass spectrometry (GC/MS) especially for the generated alkylnaphthalenes and alkylphenanthrenes. Both the asphaltenes produce aliphatic as well as aromatic compound classes. Alkylnaphthalenes and alkylphenanthrenes were identified by using reference chromatograms and literature data and the distributions used to assess thermal maturity of the asphaltenes. The ratios of β -substituted to α -substituted isomers of both alkylnaphthalenes and alkylphenanthrenes revealed higher maturity of the JN asphaltenes than the DK asphaltenes. For both the asphaltenes, the abundance of 1-methylphenanthrene dominates over that of 9-methylphenanthrene showing the terrestrial nature of the organic matter.     

Dielectric relaxation in double perovskite oxide,Ho<Subscript>2</Subscript>CdTiO<Subscript>6</Subscript>

A new double perovskite oxide holmium cadmium titanate, Ho₂CdTiO₆ (HCT), prepared by solid state reaction technique is investigated by impedance spectroscopy in a temperature range 50–400°C and a frequency range 75 Hz–1 MHz. The crystal structure has been determined by powder X-ray diffraction which shows monoclinic phase at room temperature. An analysis of complex permittivity with frequency was carried out assuming a distribution of relaxation times as confirmed by Cole–Cole plot. The frequency dependent electrical data are analysed in the framework of conductivity and electric modulus formalisms. The frequencies corresponding to the maxima of the imaginary electric modulus at various temperatures are found to obey an Arrhenius law with an activation energy of 0·13 eV. The scaling behaviour of imaginary part of electric modulus suggests that the relaxation describes the same mechanism at various temperatures. Nyquist plots are drawn to identify an equivalent circuit and to know the bulk and interface contributions.     

Expert system for autonomous handling of elementary assembly operations†

This paper addresses the new conception of a real-time expert system for elementary two-arm assembly operations under the inclusion of operation-based vision. Every operation is represented by a local blackboard which contains a recognition part, a world model and a measurement part. The total set of these behaviour-oriented modules is supervised and scheduled by an operation monitor, which is again a blackboard. The local-knowledge sources of each individual blackboard receive sensor signals as input and can directly produce a reaction without going to a higher-level global-inference engine. This local, short connection between sensor signal and reflex is decided on the basis of compiled rules which have the form of production rules. The main types of these rules are regulation tasks depending on the operation and analysis rules for situation assessments. Global plans are produced as assembly graphs and transmitted in parts to the operation monitor as task specifications. A 3-D CAD modeller is used to support the object representation and recognition     

A new formulation of operation allocation problem in flexible manufacturing systems: mathematical modelling and computational experience

This paper extends the formulation of the operation allocation problem to include the important planning aspects of refixturing and limited tool availability. A 0–1 integer programming formulation is proposed with two objective functions and a set of realistic constraints. The computational behavior of the solution is discussed and a number of observations prompted by the solution methodology have been made.     

MASS TRANSFER AUGMENTATION DUE TO WALL SLIP IN HAEMODIALYSERS†

The inadequacy of the current theories to accurately predict the haemodialyser performance is shown to be a result of the effective slip at the membrane surface. This slip phenomenon, manifested by the Fahraeus-Lindqvist effect is peculiar to (heterogeneous) blood flow. Literature data have been analyzed to substantiate the slip hypothesis proposed in this work. Both the theoretical analysis and the experimental observations indicate that slip enhances haemodialyser performance. Some design considerations have been provided, which will account for the beneficial effect of wall slip in practical haemodialyser operations.