Underpinning-based simultaneous extraction of contiguous sections of a thick coal seam under weak and laminated parting

Around 12.5 m-thick Zero seam of Chirimiri colliery underneath Bartunga hill of M/s South Eastern Coalfield Limited (SECL) was found in two sections; 3.5 m top and 6.0 m bottom section, with a highly laminated 3.0-m-thick parting between the two sections. The laminated parting, comprised of alternate layers of shale, carbonaceous shale, coal and mudstone, was found to be incompetent for safe and clean underground working of both sections. Both top and bottom sections were developed on superimposed pillars along the floor using roof bolts. Based on laboratory testing and investigations on simulated models, an idea of underpinning was conceived for simultaneous depillaring of both the contiguous sections. Taking advantage of presence of openings in the top section, the laminated parting and roof coal band of bottom section was reinforced simultaneously by a full-column grouted cable bolt of suitable length from the floor of the top section. Underpinning consolidated parting stability through reinforcement and provided additional thickness to the critical parting thickness as the roof coal band of the thick bottom section is stitched together with the parting. Maintaining superimposition of workings in the two sections, pillars of both the sections were extracted by splitting and slicing. Splits and slices of the bottom section did not experience roof instability problems due to the presence of the reinforced overlying roof coal band and parting by underpinning. The roof coal of the bottom section was blasted down on retreat. Consolidation of the multi-layered parting by underpinning did not allow separation and collapse of its mudstone/shale layers resulting in clean coal blasted from the roof. Underpinning-based simultaneous depillaring of the contiguous sections proved its technological feasibility and success through field trials.     

The catalytic steam gasification of chars from various sources by K2CO3

Gasification of a char prepared from hydrocracked residuum was compared with the gasification of chars prepared from bituminous and sub-bituminous Canadian coals, wood and graphite. Each material was mixed with 10 mass per cent K₂CO₃ and pyrolyzed up to 900°C. The yield of char was inversely proportional to the amount of volatile matter in the original material. The char prepared from hydrocracked residuum was different from the others. The other chars all followed zero-order gasification kinetics. Gasification of char prepared from the residuum was first-order in the solid. The development of a liquid phase during the pyrolysis of the residuum to char may explain this difference. The gasification rate of the char. from residuum was slower than the rates with the two coal chars and the wood char, but faster than the gasification rate of graphite. A combination of transient experiments and X-ray photoelectron spectroscopic (XPS) measurements indicated that hydrogen was formed almost instantaneously when steam reacted with the char. XPS spectra at liquid nitrogen temperature indicated that during gasification the formation of carbon oxygen bonds proceeded in the following sequence: COH, CO and CO.     

Optical properties of Dy<Superscript>3+</Superscript>-doped sodium–aluminum–phosphate glasses

Trivalent dysprosium (Dy³⁺)-doped sodium–aluminum–phosphate (NAP) glasses were prepared and characterized by their optical absorption, excitation, emission spectra, and decay time measurements. Judd–Ofelt intensity parameters were derived from the absorption spectrum and used to calculate the radiative lifetime and stimulated emission cross section of the ⁴F_9/2 → ⁶H_13/2 and ⁴F_9/2 → ⁶H_15/2 transitions. The luminescence intensity ratio of ⁴F_9/2 → ⁶H_13/2 to ⁴F_9/2 → ⁶H_15/2 transitions of Dy³⁺ in NAP glasses gives the feasibility of extracting white light. The lifetime and quantum efficiency of ⁴F_9/2 level is found to be higher than other reported glasses. With increase in Dy³⁺ ion concentration, the decay from ⁴F_9/2 level is found to be faster with decrease in lifetime due to cross relaxation between Dy³⁺ ions.     

Beta-lactamase inhibitors: agents to overcome bacterial resistance

Parental illness can have a profound impact on family relationships and children's behaviour. The amount and nature of communication between parents and children about the illness can play an important role, both positively and negatively, in mediating the outcomes. When children have a disability, families can be reluctant to communicate with them about family difficulties. They are often concerned about the impact that parental unavailability may have on their child's life. This paper reports on three families in which the mother was diagnosed with breast cancer and one child in the family had a disability. The extent and specific characteristics of their communication about the maternal illness with their children, behavioural changes in the children, explanations of communication strategies and attributions of behavioural changes are described. Family coping strategies are examined with reference to Lazarus's process model of stress and coping and the use of either problem-focused or emotion-focused strategies. Implications for possible clinical interventions are proposed. In particular it is suggested that families be offered consultation about: what children might understand; ways in which to communicate effectively; and strategies for coping with the long-term implications of serious parental illness.     

Oxynitride gate dielectric grown in nitric oxide (NO): the effectof reoxidation on dielectric reliability of the active edge

Reoxidation of an oxynitride gate dielectric grown by NO anneal of thermal oxide has been studied. This process has demonstrated ~3-5X improvement of Q_BD of active edge intensive capacitors in comparison to thermal oxide, N₂O and NO oxynitride. This improvement is believed to be due to the reduction of local thinning of the gate dielectric at the field oxide edge which also reduces local build-up of positive charge near the gate electrode at the isolation edges     

On the extension of a crack due to rigid inclusions

Dislocation layers have been utilized to study the effect of rigid inclusion on the crack extension in an infinite body and thereby to derive the crack extension condition from Irwin's criterion. Some particular cases have also been considered.

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Résumé On a eu recours aux couches de dislocation pour étudier l'effet d'une inclusion rigide sur l'extension d'une fissure dans un corps infini et déterminer en conséquence les conditions d'extension d'une fissure en utilisant le critère d'Irwin. Certains cas particuliers ont également été considérés.

     

Untersuchungen über die Zähigkeit von Hözern.—Zweite Mitteilung Die Abhängigkeit des Dämpfungs- und Rückprallfaktors von der Stützweite,der Probenbreite und Probendicke beim Schlagbiegeversuch mit dem Hatt-Turner-Fallwerk

Zusammenfassung In Fortführung früherer Versuche über die Z?higkeit von H?lzern wurden die Schwankungen des D?mpfungsund Rückprallfaktors mit der Stützweite sowie der Probenbreite und Probendicke von Holzst?ben in einem Hatt-Turner-Fall-werk untersucht. In ?hnlicher Weise wurde der H?henverlust, d. h. der Werth ₀−h ₁, beim ersten Rückprall bei ?nderung der drei Werteh, d undl bestimmt. Aus früheren Ans?tzen von F. Kollmann und den in der ersten in Indien erschienenen Mitteilung über die Versuche abgeleiteten Beziehungen ergaben sich theoretische Zusammenh?nge, die sich durch die Versuchsergebnisse best?tigfen. Die physikalische Bedeutung des D?mpfungs- und Rückprallfaktors wurde er?rtert und die Eignung dieser Werte bei mechanischen Eigenschafts-prüfungen der H?lzer, ggf. auch für festzusetzende Prüfnormen, diskutiert. Die erste Mitteilung (vgl. 1) erschien in englischer Sprache in einer Ver?ffentlichung des Forest Research Institute Dehra Dun (Indien). N?heres über das Hatt-Turner-Fallwerk siehe in: Kollmann, F.: Technologie des Holzes und der Holzwerkstoffe, 2. Aufl., Bd. 1, S. 826, Berlin/G?ttingen/Heidelberg/ München 1951. Die Arbeit entstand auf Anregung von F. Kollmann.