A space communication study Final report, 15 Sep. 1967 - 15 Sep. 1968

Transmitting and receiving analog and digital signals through noisy media - space communications stud

Structure-property characterisation of ternary phase polypropylene composites

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.An investigation to study factors controlling the structure and properties of binary- and ternary-phase polypropylene (PP) composites containing ethylene-propylene rubber (EPR) and glass beads has been carried out. The composite structure was evaluated using various techniques including SEM, DSC, XRD and DMA. While the mechanical tests included tensile and impact measurements at ambient temperature, and a fracture toughness test based on the J-integral method carried out at -20 oC. EPR and glass beads were found to influence the structure and properties of polypropylene in different ways. Incorporation of EPR into polypropylene results in an improvement in impact strength and toughness, accompanied by a decrease in tensile strength and modulus. The opposite was found for composites containing glass beads. Polypropylene composites with balanced mechanical properties were achieved by physical blending of this polymer with both EPR and glass beads. The effect of composite structure, composition and processing variables on the properties of the ternary systems were analysed. A study of their morphology has shown that two kinds of phase structure can be formed, either a separate dispersion of the phases, or encapsulation of the filler by rubber. Factors controlling these structures are believed to be due mainly to the surface characteristics of the components. Modification of EPR by maleic-anhydride grafting results in composites with rubber encapsulation of the filler, with FTIR revealing a reaction between these phases. Composites containing unmodified EPR, on the other hand, show separate dispersion of the components. The former composites, with good adhesion at the rubber and filler interface, have noticeably higher impact strength and fracture toughness at and below ambient temperatures, while the latter variant is characterised by higher tensile strength and modulus, accompanied by a lower impact strength. Improvements in impact strength of the composites was also achieved by promoting adhesion between the polymer and filler interface using surfacecoated glass beads, or by increasing the number of rubber particles adhering to the glass bead surfaces using a two-step mixing technique. Results of the present study have thus shown that mechanical properties of ternary phase polypropylene composites can be adjusted, to a certain extent, by controlling their morphologies through the use of suitable functionalised materials and also by using an appropriate compounding methodology.This study is funded by the Royal Thai Government

NASA Tech Briefs, Winter 1977

Topics include: NASA TU Services: Technology Utilization services that can assist you in learning about and applying NASA technology; New Product Ideas: A summary of selected innovations of value to manufacturers for the development of new products; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Life Sciences; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences

Energy. A continuing bibliography with indexes, issue 36, January 1983

This bibliography lists 1297 reports, articles, and other documents introduced into the NASA scientific and technical information system from October 1, 1982 through December 31, 1982

THE SEDIMENTARY EVOLUTION OF THE 'EXMOOR BASIN' DURING THE LATE EMSIAN - EARLY EIFELIAN: THE LYNTON FORMATION

An integrated investigation of the sedimentological, ichnological and syn-sedimentary tectonic aspect of the late Emsian to early Eifelian Lynton Formation (Lynton Beds of previous studies) has revealed a varied mudstone-dominated shallow marine succession which accumulated in a rapidly subsiding rifted basin. The 'Exmoor Basin' developed in response to a Devonian phase of transtension associated with dextral shear along a fundamental east-west lineament to the north (the Bristol Channel Fault Zone). The Lynmouth - East Lyn Fault (a splay off the BCFZ?) was active throughout the deposition of the Lynton Formation and strongly influenced the depositional styles developed along its length. A re-evaluation of the p/subsidence curve for the 'Exmoor Basin' using the latest biostratigraphic and lithological thickness data indicates a pattern consistent with a strike-slip basin; Carboniferous thermal phase p/subsidence values suggest only 10% crustal thinning compared to values c. 50 % claimed be previous authors (Dewey 1982, Sanderson 1984). The base of the exposed Lynton Formation is characterised by extensive intraformational slide deposits and the presence of phosphatic material which represents a highstand deposit that correlates with the eustatic transgressive T-R event Ic of Johnson et al. (1985). Following a period of gradual reduction in accomodation space the sequence was punctuated by a massive influx of sand and granule grade material deposited at the base of the Lynmouth - East Lyn Fault scarp. This material was swept together into a series of offshore sand ridges and a shoreface deposit adjacent to the fault scarp. A new process-response model has been developed to describe the offshore sand ridges that were moulded by a combination of semi-permanent trade wind induced geostrophic flow, oscillatory currents and (possibly) weak tides. The central part of the Lynton Formation records a gradual upwards increase in relative accomodation space and decrease in the influence of semi-permanent currents; dysaerobic substrates became widespread and a localised anoxic mud developed offshore. The transition into the overlying Hangman Sandstone Group was marked by the southward progradation of a sandy shoreline in the face of a period of world-wide eustatic sea-level rise. The older, more northerly shoreline was dominated by longshore currents whilst the younger shoreline preserved a mixed (lower energy) storm- and wave-dominated sequence. The rate of shoreline progradation was relatively slow and the Lynton Formation - Hangman Sandstone Group boundary is markedly diachronous; the thickness of the exposed Lynton Formation varies from 200m adjacent to the Lynmouth - East Lyn Fault, where previously unrecognised outliers of the Hangman Sandstone Group occur, to 250m some 5km down-palaeoslope. Although the ichnofauna was locally diverse, with 27 distinct ichnotaxa recognised within the Lynton Formation, the succession was dominated by a gradation between straight Palaeophycus tubulraris burrows and branching Chondrites systems reflecting the response of an organism tolerant to dysaerobic conditions. The study demonstrates the value of integrating sedimentological, ichnological and structural techniques when studying Devonian marine shelf successions which accumulated m a tectonically unstable setting

EUROSENSORS XVII : book of abstracts

Fundação Calouste Gulbenkien (FCG).Fundação para a Ciência e a Tecnologia (FCT)

Intelligent Systems

This book is dedicated to intelligent systems of broad-spectrum application, such as personal and social biosafety or use of intelligent sensory micro-nanosystems such as "e-nose", "e-tongue" and "e-eye". In addition to that, effective acquiring information, knowledge management and improved knowledge transfer in any media, as well as modeling its information content using meta-and hyper heuristics and semantic reasoning all benefit from the systems covered in this book. Intelligent systems can also be applied in education and generating the intelligent distributed eLearning architecture, as well as in a large number of technical fields, such as industrial design, manufacturing and utilization, e.g., in precision agriculture, cartography, electric power distribution systems, intelligent building management systems, drilling operations etc. Furthermore, decision making using fuzzy logic models, computational recognition of comprehension uncertainty and the joint synthesis of goals and means of intelligent behavior biosystems, as well as diagnostic and human support in the healthcare environment have also been made easier

Prediction of single crystal instability in channel-die compression using Rice's criterion

International audienceThis work concerns the behavior and instability of cold-deformed single crystals at large strains. The theoretical calculations integrate a phenomenological deformation model of the single crystal based on a polynomial approximation of the flow surface, within the limits of the homogeneous analysis of the deformation of the specimen. It is introduced in the context of three-dimensional kinematics, in which the strains and the gradients of the rate tensor are represented by higher triangular matrices. It accounts for the lattice rotation of the single crystals in the channel-die for several initial orientations representative of the rolling textures. The above formalism allows implementing Rice’s criterion of bifurcation into shear bands. It appears that the localization occurs for all crystallographic orientations, whether they rotate or not in the channel-die. The difference is in the earliness of the onset. The confrontation between theory and experience is presented using various results of the literature and data from the compression of single crystals in the authors’ laboratory. Although a variety of factors trigger instabilities, from the dislocation microstructure to the friction on the sample, Rice’s criterion proves efficient in predicting what happens within the grains. It accounts for the numerous shearing zones which can be spotted in the deformed metals