Science.gov (United States)

structures made out of composite laminates and/or composite sandwich panels. A Spectral Finite Element Method (SFEM) [19, 20] is used for evaluating the ...

Energy Technology Data Exchange (ETDEWEB)

An experimental study was conducted to determine the effects of ply thickness in composite laminates on thermally induced cracking and changes in the coefficient of thermal expansion (CTE). After a few thermal cycles, laminates with thick-plies cracked, resulting in large changes in CTE. CTE`s of the thin-ply laminates were unaffected by microcracking during the first 500 thermal cycles, whereas, the CTE`s of the thick-ply laminates changed significantly. After about 1500 cycles, microdamage had also reduced the CTE of the thin-ply laminates to a value of about half of their initial value.

British Library Electronic Table of Contents (United Kingdom)

Annealing of magnetostrictive Metglas foils, subsequently incorporated into laminated Metglas/Pb(Zr, Ti)O3 magnetoelectric (ME) composites, is shown to result in improved magnetic properties, as well as ME coefficients. Annealing of the foils at 350 ?C resulted in partial crystallization, without oxidation or magnetic cluster formation that would reduce the magnetization. Laminate composites made with these annealed Metglas foils had improved ME coefficients.

Energy Technology Data Exchange (ETDEWEB)

A plane stress constitutive relation is developed for laminate composites undergoing matrix cracking and therefore displaying significant nonlinear stress-strain behavior. The constitutive relation is similar in some respects to a phenomenological theory of plasticity in that it is fit to data from uniaxial tests. The constitutive equations are specialized to brittle matrix composites (especially CMCs) in the form of cross-piles and quasi-isotropic laminates. Several problems involving stress redistribution at holes and notches due to nonlinear stress-strain behavior are investigated with the aid of the constitutive law.

Science.gov (United States)

A flutter-motion equation is presently derived for a 2D composite sandwich panel considering the total lateral displacement of the plate as the sum of the displacement due to bending of the plate, and that which is due to shear deformation at the core. The effects of core thickness and stacking sequence of the faces on the flutter boundary of the plate are discussed; it is shown that the sandwich panel greatly improves the flutter boundary over that of a composite laminate panel, provided it has sufficient core thickness.

Energy Technology Data Exchange (ETDEWEB)

A porous tooling system was selected for the processing of Graphite/PMR-15 Polyimide laminates in thickness up to 3.2 mm. (0.125 inch). This tool system must have a reasonable strength, permeability dimensional stability, and thermal conductivity to accomplish curing at 600 F and 200 psi and 200 psi autoclave temperature and pressure. A permeability measuring apparatus was constructed and permeability vs. casting water level determined to produce tools at three different permeability levels. On these tools, laminates of 5, 11, and 22 plies (.027, .060, and 0.121 inch) were produced and evaluated by ultrasonic, mechanical, and thermal tests to determine the effect of the tool permeability on the cured laminates. All tools produced acceptable laminates at 5 and 11 plies but only the highest permeability produced acceptable clear ultrasonic C-Scans. Recommendations are made for future investigations of ...

Energy Technology Data Exchange (ETDEWEB)

To predict the fatigue life of fiber reinforced composites, fatigue process of CFRP laminates of [0 /90 ]{sub s} is investigated and the influence of damages occurring at fiber, matrix and fiber/matrix interface on the various critical strengths and the relationship between residual critical strength and failure are discussed. As a result, it was shown that fatigue strength (i.e. fatigue life) consisted of residual critical strength and stresses occurring at each layer (0 and 90 layers) and interlayer. Moreover, the fatigue failure occurred because the residual critical strength of each layer and interlayer decreased with dependence of their microdamage densities, so that the fatigue life can be predicted by evaluating microdamage behavior in fatigue process. (orig.) 14 refs.

Energy Technology Data Exchange (ETDEWEB)

To heighten durability and safety of materials/parts for undersea oil drilling, the development of ceramic base materials was made by developing function harmony type process technology which harmonizes on a high grade contrary characteristics and various functions. The paper summed up the fiscal 1997 results. In the design of system formation, computational simulation technology was developed to the composite process and the diploid system. The development of multifunction simultaneous manifestation materials was trially made by the higher nano structure process. A study was made of control of microstructures of porous materials and matrix filling by the gas phase precipitation control. Proposed were selective control of grain growth from species crystals and the columnar particle orientation laminated structure of simultaneous manifestation of strength and toughness. By composite ...

Energy Technology Data Exchange (ETDEWEB)

Kerf geometry, kerf wall features, and cutting front characteristics of an Abrasive Waterjet (AWJ) machined Graphite/Epoxy (Gr/Ep) laminate were studied. A macroscopic analyses suggests that geometrical features associated with AWJ machining of Gr/Ep laminates are influenced by three macro regions along the cutting depth. The presence of these regions, including initial damage at jet entry, smooth cutting, and rough cutting near the jet exit, depends on the operating conditions. Design of experiments and analysis of variance were used to determine the effect of cutting parameters on kerf characteristics and to develop empirical models for kerf profile and features of the three distinct macroscopic regions. Cutting front analysis revealed that the mechanisms of material removal in AWJ machining of Gr/Ep do not change over the jet penetration depth. In general, high quality uniform cuts may be obtained by minimizing initial damage at the jet ...

Energy Technology Data Exchange (ETDEWEB)

This invention relates to the production method of composite electrode substrate for fuel cell. An impermeable material is used for edge sealant. The sealant is put in the clearance between two electrodes consisting of porous carbon material via thermoplastic resin sheet, and heated while being pressed. This production method increases the adherence between the porous carbon bodies and reduces the contact resistivity at the joint interface. Consequently, it becomes possible to produce the composite electrode for fuel cell without separator, resulting in simplification of assembly work, weight reduction, and downsizing. The preferable porous carbon body is made from shrinkage-treated fiber. After sheet forming, the thermosetting resin is impregnated, and then it is burnt to carbonization. Or mixed sheet of rayon and acrylic fiber is laminated to be heated and pressed without impregnating the resin. The pressed resin is then ...

Science.gov (United States)

... ordnance requirements. Descriptors : *Combustible cartridge cases, *Patents, Laminates, Felts, Flame inhibitors, Films. Subject ...

International Science & Technology Center (ISTC)

Development of Ceramic Composite Materials and Structural Elements for High-Temperature Nuclear Reactors

Science.gov (United States)

Minimum weight design is an important criterion in aircraft and spacecraft because it allows either an increased pay-load or higher performance. As a result, the use of composite sandwich panels has grown due to their light weight and high rigidity. In order to further increase the efficiency of these structures, designers have used different materials in different shapes in the facesheets and in the core. One of the most recent innovations has been the use of a uniform net of carbon fibre/epoxy as the facesheets. In the present study, the optimal design of sandwich plates with heterogeneous, facesheets is treated. The plate mass is minimized, considering the first natural frequency and certain failure loads as constraints. Weight reduction is obtained by defining a nonuniform distribution of composite material in the facesheets. Initially, the facesheets are assumed to be constructed of composite ...

Science.gov (United States)

... at the end of this report. A. Low-Velocity Impact of Composite Sandwich Panels In 2007, the PI developed analytical solutions ...

British Library Electronic Table of Contents (United Kingdom)

Abstract We have experimentally and theoretically investigated the equivalent magnetic noise in a magnetoelectric Metglas/ 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 laminate sensor unit by considering the constituent noise sources of dielectric loss (NDE) and DC leakage resistance (NR). In the low frequency range (f = 1 Hz), theory predicts that NR dominates the noise charge (1.6 times larger than NDE), with a 1 Hz noise of 9.1\\;{\\rm pt}/\\sqrt {\\rm Hz}. The experimental equivalent magnetic noise was 10.8\\;{\\rm pt}/\\sqrt {\\rm Hz}. This observed value is slightly higher than the predicted one, which might be due to an oversimplification of the theoretical model in terms of electrical charge amplifier and external vibration noise sources. ( 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

International Nuclear Information System (INIS)

Comprehensive investigation has been made into the application of the polymerization hardening by radiation, particularly electron beam, to the composites of polymers and other materials. The report is divided into four parts, namely 1) characteristics and problems of the reaction of curing by radiation polymerization, 2) improvement of the bonding capability of high molecular weight materials, 3) bonding by radiation, and 4) composites made by the impregnation and polymerization hardening of monomers. The first part includes the effects of dose rate, temperature rise during the hardening, the peculiarity of electron beam irradiation at high dose rate, reaction environment and additive effects. Main conclusions are as follows: caution must be taken to the amount of residual double bonds because they affect the quality of hardened polymers; the polymerization hardening reaction at high dose rate cannot be analogized by that at low dose rate; and ...

Energy Technology Data Exchange (ETDEWEB)

This report presents a brief description of the fabrication and advantages of a composite, carbon-metal fiber material which does not require lubrication.

Science.gov (United States)

The objectives of the Phase-I research address the development of mechanics- based structural integrity analysis methodologies for composite sandwich panels ...

Energy Technology Data Exchange (ETDEWEB)

A lightweight, low permeability liner for graphite epoxy composite compressed gas storage vessels. The liner is composed of polymers that may or may not be coated with a thin layer of a low permeability material, such as silver, gold, or aluminum, deposited on a thin polymeric layer or substrate which is formed into a closed bladder using torispherical or near torispherical end caps, with or without bosses therein, about which a high strength to weight material, such as graphite epoxy composite shell, is formed to withstand the storage pressure forces. The polymeric substrate may be laminated on one or both sides with additional layers of polymeric film. The liner may be formed to a desired configuration using a dissolvable mandrel or by inflation techniques and the edges of the film seamed by heat sealing. The liner may be utilized in most any type of gas storage system, and is particularly applicable for hydrogen, gas ...

Science.gov (United States)

This study investigated weathering effects on polyvinyl chloride (PVC) based wood plastic composites (WPC), with a focus on the color and structure that is attributed to the material composition. It is directed towards quantifying the main chemical modifi...

UK PubMed Central (United Kingdom)

The mechanical properties of laminated window profiles manufactured using two types of adhesives were determined. The objective of this study is to evaluate the effects of heat treatment on some mechanical...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A core preservation package was developed to maintain the reservoir characteristics of core samples and consequently to improve the quality of data obtained through laboratory core analyses. The package is a heat-sealable plastic-aluminum laminate similar to those common in the food-packaging industry. The laminated core preservation package acts as an impermeable barrier to water vapor and gases, and is resistant to chemical alteration and degradation by core fluids. These performance characteristics result in effective core preservation by maintaining the fluid content of the core. Other advantages of the laminated package are that it is fast and simple to use and eliminates the cumbersome dip-coat step used in some core preservation methods.

International Nuclear Information System (INIS)

Silicon/carbon composite anode materials were prepared by pyrolyzing the phenol-formaldehyde resin (PFR) mixed with silicon and graphite powders. Scanning electron microscopic (SEM) observation showed that the morphology stability of the composite electrodes can be retained during cycling. A structure evolution mechanism is proposed to illuminate the enhancement of cycleability of the composite electrode. The composite used as anode material for lithium ion batteries possesses a reversible capacity of over 700 mAh/g.

Science.gov (United States)

... energy absorption characteristics of composite sandwich panels, thermoplastic energy-absorbing subfloor structures, and shoulder belt pre- tensioners. ...

Science.gov (United States)

... Composite sandwich panels with fiber reinforced plastic (FRP) faces and low 3 density foam cores are fast becoming the structural material of ...

British Library Electronic Table of Contents (United Kingdom)

Rheological properties of moderately concentrated solutions of cellulose in methylmorpholine N-oxide-dimethylformamide mixtures containing hydrophilic montmorillonite nanoparticles were studied. Film composite materials were prepared, and their physicomechanical properties and structural organization were studied.

Science.gov (United States)

... Title : Wear Rate and Friction Coefficient in Liquid Nitrogen and Hydrogen of Steel Sliding on Polymer Laminates (Various Fabrics and Polymers. ...

Energy Technology Data Exchange (ETDEWEB)

The nuclear lamina proteins, prelamin A, lamin B, and a 70-kD lamina-associated protein, are posttranslationally modified by a metabolite derived from mevalonate. This modification can be inhibited by treatment with (3-R,S)-3-fluoromevalonate, demonstrating that it is isoprenoid in nature. We have examined the association between isoprenoid metabolism and processing of the lamin A precursor in human and hamster cells. Inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase by mevinolin (lovastatin) specifically depletes endogenous isoprenoid pools and inhibits the conversion of prelamin A to lamin A. Prelamin A processing is also blocked by mevalonate starvation of Mev-1, a CHO cell line auxotrophic for mevalonate. Moreover, inhibition of prelamin A processing by mevinolin treatment is rapidly reversed by the addition of exogenous mevalonate. Processing of prelamin A is, therefore, dependent on isoprenoid metabolism. ...

UK PubMed Central (United Kingdom)

In several respects the dorsal thalamus of Trichosurus presents a level of organizational complexity considerably in advance of that seen in Didelphis. In particular, such features as the lamination...Full Text Available

Science.gov (United States)

Sep 18, 2007 ... Lightweight structural aerogels would find applications as a component of composite sandwich panels that are both lightweight and insulating ...

Science.gov (United States)

Mar 1, 2011 ... thermal behavior and structural changes of composite sandwich panels with a honeycomb core subjected to a variety of environmental effects. ...

Energy Technology Data Exchange (ETDEWEB)

A thesis is presented on improving the understanding of the fatigue properties of wood and fatigue failure mechanisms in the design of wind turbine blades. Three main areas were researched: the effect of R ratio on fatigue life, the effect of moisture on fatigue life and the development of cumulative damage laws. Tests were carried out on mainly four-ply laminates. Recommendations to future work are outlined. (U.K.).

International Nuclear Information System (INIS)

This experiment was done to determine the effects of irradiation on the physical properties of three kinds of laminated packaging materials, i.e. polypropylene-polypropylene, polypropylene-polyethylene, polyester-polyethylene. Observations were made on pinhole production, leakage, oil resistance, resistance against insect penetration, colour, odour tensile strength, elongation at break, seal strength and tear resistance. The samples were irradiated with doses of 0, 5 and 10 kGy, then stored at room temperature and examined after 0, 3, 6 and 12 months of storage. The results showed that irradiation doses up to 10 kGy, as well as storage up to 12 months, did not create pinholes, or leakage in pouches prepared from laminated films. The resistance of the films to oil and insect penetration, the colour, and the odour were also unchanged. Both irradiation and storage treatments had a significant effect on physical properties of the ...

British Library Electronic Table of Contents (United Kingdom)

A method for estimating the form of magnetic nanoparticles in composite film structures based on the observation of ferromagnetic resonance phenomenon is offered. Within the model of the effective medium, an explanation is given for experimentally observed concentration and temperature dependences of resonant fields for composite nanosystem (Co45Fe45Z10) f +(Al2O3)100?f .

Science.gov (United States)

We proposed and numerically investigated the influence of spatial symmetry on the terahertz frequency region response of composite planar metamaterials based on deformed split ring resonators. Compared with the original simple structures, the composite metamaterials with different spatial symmetries exhibited exotic electromagnetic properties. The electromagnetic response of a specific configuration with C4 symmetry was identical to the structure with simple lattice. Especially, for configurations with broken symmetry, very sharp Drude-like resonances with high quality factor were observed. The electric field and current distribution associated the resonances were analyzed for deep understanding of the underlying physical properties.

International Nuclear Information System (INIS)

The aim of this paper was to describe ability to intercalation of laboratory prepared carbon composites and their constituents. In work the following materials were tested; pinch-based fibres of P-120 and K-1100 manufacturer's designations, carbon matrix and resulting composites. To prepare a matrix of composites, phenol-formaldehyde resin (Z) and pinch-based precursor (PAK) were used. After initial carbonization, the carbon matrix was heated to 2150 "oC i to improve ability to the future intercalation. Three kinds of composites (P/Z, K/Z and K/PAK), with two directional reinforcement (2D), were prepared. All carbon samples were intercalated with copper chloride(II). To study the structure of all materials, before and after intercalation, X-ray diffraction method was used. It enabled to measure microstructure parameters (L_c and L_a), interplanar distance (d_0_0_2) thickness of an ...

Energy Technology Data Exchange (ETDEWEB)

Recently, the development of shape memory alloy (SMA) actuators, in the forms of wire, thin film and stent have been found increasingly in the fields of materials science and smart structures and engineering. The increase in attraction for using these materials is due to their many unique materials, mechanical, thermal and thermal-mechanical properties, which in turn, evolve their subsequent shape memory, pseudo-elasticity and super-elasticity properties. In this paper, a common type of SMA actuator, Nitinol wires, were embedded into advanced composite structures to modulate the structural dynamic responses, in terms of natural frequency and damping ratio by using its shape memory and pseudo-elastic properties. A simple theoretical model is introduced to estimate the natural frequency of the structures before and after actuating the embedded SMA wires. The damping ratios of ...

CERN Document Server

In order to reduce the activation temperature of the TiZrV alloy, thin films of various compositions were produced by three-cathode magnetron sputtering on stainless-steel substrates. For the characterisation of the activation behaviour the surface chemical composition has been monitored by Auger electron spectroscopy during specific in situ thermal cycles. The volume elemental composition of the film has been measured by energy dispersive X-ray spectroscopy and the morphology (crystal structure and size of the crystallites) has been investigated by X-ray diffraction. The criteria indicating the sample quality and its dependence on film structure and chemical composition are presented and discussed. (13 refs).

Energy Technology Data Exchange (ETDEWEB)

A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface.

Energy Technology Data Exchange (ETDEWEB)

This paper describes the development of cellulose paper/plastic film/cellulose paper laminate insulated Self-Contained 500 kV Oil-Filled (OF) Cable and its accessories. Dielectric loss of this new cable was confirmed to be about one third that of conventional kraft paper cable. Moreover, by employing the reduced insulation thickness of 25 mm rather than that of 33 mm, as is usual with conventional cables, the new cable could be made very compact, due to the high dielectric strengths of laminated paper. As a result, the shipping reel length of the new cable, which is about 10% lighter in total weight and 10% smaller in overall diameter than conventional cables, could be dramatically increased. The reliability and the stability of the new cable have been demonstrated by the successful completion of a one and a half year field test.

British Library Electronic Table of Contents (United Kingdom)

Abstract Poly(butylene terephthalate) (PBT) composites containing multiwalled carbon nanotubes (MWCNTs) were prepared using a melt-blending process and used to examine the effects on the composite structure and properties of replacing PBT with acrylic acid-grafted PBT (PBT-g-AA). PBT-g-AA and multihydroxyl-functionalized MWCNTs (MWCNTs-OH) were used to improve the compatibility and dispersibility of the MWCNTs within the PBT matrix. The composites were characterized morphologically using transmission electron microscopy, and chemically using Fourier transform infrared, solid-state 13C NMR and UV-visible absorption spectroscopy. The antibacterial and electrical conductivity properties of the composites were also evaluated. MWCNTs or MWCNTs-OH enhanced the antibacterial activity and electric...

International Nuclear Information System (INIS)

Composite materials of synthetics (based on monomers, oligomers and thermoplastics) and of natural polymers (wood and other fibrous cellulosics) prepared by radiation processing, offer valuable structural materials with enhanced coupling forces between the components. The applied polymer chemistry of such composites shows several common features with that of radiation grafting, e.g. the polymerization rate of oligomer-monomer mixtures in wood remains in most cases proportional to the square-root of the initiating dose-rate, just as in the simultaneous grafting, demonstrating that the chain termination kinetics remain regularly bimolecular in the corresponding dose-rate ranges. In the processing experiences of such composites, low dose requirement, easy process-control, and good technical feasibility have been found for composites of wood with oligomer-monomer mixtures, for coconut ...

International Nuclear Information System (INIS)

In this review, we demonstrate the developmental appearance, structural features, and reorganization of transient cerebral zones and structures in the human fetal brain using a correlative histological and MRI analysis. The analysis of postmortem aldehyde-fixed specimens (age range: 10 postovulatory weeks to term) revealed that, at 10 postovulatory weeks, the cerebral wall already has a trilaminar appearance and consists of: (1) a ventricular zone of high cell-packing density; (2) an intermediate zone; (3) the cortical plate (in a stage of primary consolidation) with high MRI signal intensity. The anlage of the hippocampus is present as a prominent bulging in the thin limbic telencephalon. The early fetal telencephalon impar also contains the first commissural fibers and fornix bundles in the septal area. The ganglionic eminence is clearly visible as an expanded continuation of the proliferative ventricular zone. The basal ganglia showed an ...

Energy Technology Data Exchange (ETDEWEB)

This work contains 27 chapters which cover recent advances in fracture mechanics applied to cement-based composites: concrete, reinforced concrete, and fiber reinforced concrete. The book, based on a NATO Advanced Study Institute, is a comprehensive survey of treating nonlinearity associated with crack growth in brittle materials such as cement composites, rocks and ice. The book is divided into 8 major themes: advances in nonlinear fracture mechanics; fracture processes; numerical modelling of fracture; experimental methods of determining fracture parameters; damage and continuum modelling; strain-rate and dynamic effects of crack propagation; stress-corrosion, time and temperature effects on fracture; and implications for concrete structures.

Energy Technology Data Exchange (ETDEWEB)

In 1969, the authors started R and D on a polypropylene laminated paper (PPLP) as a new low-loss insulating paper for oil-filled (OF) cables. Through the material research and the trial manufacture of 275 kV OF cable and four years of long-term field test, PPLP has reached the stage of commercial use. This paper introduces a summary of the history of the development of PPLP, the characteristics of PPLP and cable, the results of long-term field test of 275 kV cable, and other relevant data.

Energy Technology Data Exchange (ETDEWEB)

Energy Related Inventions Program Number 613 was a two year program to commercialize a unique new wear material, Metal Reinforced Carbon Composite, MRCC. The program was designed to manufacture sample components of MRCC for evaluation by potential users and manufacturers. As a result of the program Burton Technologies Inc. and Rotary Power International are forming a joint company to manufacture, market and license MRCC materials to a wide range of industries.

Energy Technology Data Exchange (ETDEWEB)

The isomeric composition of bicyclo(3.3.1)nonadienes was investigated by GLC and PMR spectroscopy with silver-lanthanide shift reagents. The absence of stereospecificity in the hydrogenation of 3,7-dimethylenebicyclo(3.3.1)nonane by hydrogen adsorbed on Raney nickel was demonstrated. This is explained by the sequence of the isomerization and then hydrogenation processes.

British Library Electronic Table of Contents (United Kingdom)

The electric explosion of a conductor being part of an electric cable is studied. It is ascertained that the electric properties of a polymeric dielectric depend nonlinearly on the maintenance of the ultradisperse metal filler. In the course of the numerous heating-cooling processes of an insulator, a streamlining of the structure of a polymeric composite occurs.

Science.gov (United States)

... describe the relationship (Peake and Quinn, 1993). The power model was considered best if the R2 from this ... when stone abundance was low (Fig. 2). The power model best described the nonlinear relations...

UK PubMed Central (United Kingdom)

Assessment of subtle changes in the primary macromolecular components of cartilage, proteoglycan (PG) and collagen, is critical for the diagnosis of early stages of osteoarthritis (OA), but...Full Text Available

UK PubMed Central (United Kingdom)

The Protein Data Bank contains the description of more than 45,000 three-dimensional protein and nucleic-acid structures today. Started to exist as the computer-readable depository of crystallographic...Full Text Available

International Nuclear Information System (INIS)

GaAs1-xPx p-n junction structures were grown on the epi-ready n-type GaAs(100) substrate by solid source MBE system for different phosphor compositions. To obtain the lattice-match sample structure was applied graded growth procedure. The structural and optical properties of the sample structures with different P concentration were investigated by using X-ray diffraction (XRD), spectroscopic ellipsometry (SE). In addition, The range of lattice parameters in the graded epilayer and phosphorous composition were determined from the HRXRD rocking curve simulation. We analyse dielectric function spectra of disordered GaAs1-xPx junction structures measured using spectroscopic ellipsometry at room temperature in the 0.6-4.7 eV photon energy region. The critical energy points such as band gap energy and spin-orbit-split energy of these ...

International Nuclear Information System (INIS)

Optimum processing parameters were searched for the pilot-scale production of wood-polyester composites by irradiation of resin-impregnated wood material. The radiation initiation of the following systems were examined in wood and without wood matrix: methyl methacrylate, mixture of styrene and acrylonitryle, and their combination with unsaturated polyester. In the most cases the over-all rate of the complete polymerization process in wood matrix is proportional to the square root of the initiation rate. The parameters of the radiation technology of wood-polyester composites have been determined, using 260 TBq (7 kCi) "6"0Co radiation source. A pilot plant has been constructed using an underwater irradiation system of 1.85 PBq (50 kCi) "6"0Co. The successful production rate of 200 kg wood-polyester composite per day, as well as the application tests have demonstrated the technical feasibility of this new ...

International Nuclear Information System (INIS)

#alpha#/#beta# sialon based composites containing silicon nitride whisker and silicon carbide platelet were fabricated by hot pressing. Effect of the reinforcing agents on the #alpha# to #beta# phase transformation of the sialon as well as on the mechanical properties was investigated. Silicon nitride whisker and silicon carbide platelet promoted the phase transformation. TEM/EDS analysis revealed that the grain containing the whisker had 'core-rim' structure; core being high purity Si_3N_4 whisker and rim being #beta#-sialon. Flexural strength of the composite decreased with the reinforcement addition which, on the other hand, improved fracture toughness of it. High temperature strength was measured at 1300 deg C to be about 130 MPa lower than that measured at RT for the whisker reinforced composite. (author).

International Nuclear Information System (INIS)

When operating a nuclear power plant the necessity arise to eliminate various defects of building constructions, to seal joints and transitional elements. The authors present data concerning the production of a sealing composition made of epoxy resin and used for NPP premises of emergency location. Analytical relations are presented between the properties of the composition (adhesion strength, water absorption and others) and its structure. Physical, mechanical and thermal properties and structural peculiarities are determined in the process of interaction between the filling and binding agents. The composition sustains sealing properties under environmental conditions at he presence of an air - vapour mixture with 160 degrees C"o temperature and 0.3 MPa surplus pressure. (author).

Energy Technology Data Exchange (ETDEWEB)

The effect of interfacial structure on the mechanical properties of aluminum-ceramic composite materials fabricated by liquid phase sintering was studied. The composites were based on two matrix alloys (powder metallurgy alloys 201 and 601) reinforced with either Al{sub 2}O{sub 3} or SiC particulate. Characterization of the interfacial regions demonstrated that the SiC-matrix interfaces were faceted whereas the Al{sub 2}O{sub 3}-matrix interfaces had an incomplete layer of a silicon-rich amorphous phase. Preferential attack of the particles during sintering is believed to cause the crystallographic facets to form on SiC. Locally high silicon concentrations near Al{sub 2}O{sub 3} particles led to the formation of a glassy phase from the reduction of Al{sub 2}O{sub 3}. The difference in interfacial structure resulted in a higher particle-matrix bond strength and therefore improved ...

Energy Technology Data Exchange (ETDEWEB)

The composition of sputter-deposited HgS films was determined by electron microprobe analysis. From the relative x-ray intensity as a function of film thickness, the depth of the ionizations that produce SK sub(..cap alpha..) and HgM sub(..cap alpha..) was found to be approximately 0.65 ..mu..m at an accelerating voltage of 15 kV. This value agreed well with a value calculated from Castaings' empirical law after absorption correction. The determination of film composition was limited to sufficiently thicker films than this critical value, usually 1 - 2 ..mu..m thick. The relation between the conposition of bulk standard determined by chemical analysis and the x-ray intensity ratio was used for the correction of film composition. The results showed that the crystal structure of HgS films was independent of the composition, i.e., the growth of metastable ..beta..-HgS films ...

Energy Technology Data Exchange (ETDEWEB)

In order to investigate the role of amorphous SiO{sub 2} particles in corrosion and wear resistance of Ni-based metal matrix composite alloying layer, the amorphous nano-SiO{sub 2} particles reinforced Ni-based composite alloying layer has been prepared by double glow plasma alloying on AISI 316L stainless steel surface, where Ni/amorphous nano-SiO{sub 2} was firstly predeposited by brush plating. The composition and microstructure of the nano-SiO{sub 2} particles reinforced Ni-based composite alloying layer were analyzed by using SEM, TEM and XRD. The results indicated that the composite alloying layer consisted of {gamma}-phase and amorphous nano-SiO{sub 2} particles, and under alloying temperature (1000 deg. C) condition, the nano-SiO{sub 2} particles were uniformly distributed in the alloying layer and still kept the amorphous structure. The corrosion ...

International Nuclear Information System (INIS)

The dependence of Tsub(c) on composition and deformation is calculated and compared with the corresponding dependence for Tsub(m). It is shown that superconducting and structural properties of A-15 compounds can be described, at least qualitatively, by the quasi-one-dimensional model previously developed by the authors. The superconductivity mechanism is assumed to be analogous to the BCS theory. The upper critical field Hsub(c2) of the V_3Si or Nb_3Sn compounds is found to be much greater than that in V or Nb.

Energy Technology Data Exchange (ETDEWEB)

In this paper structure and mechanical properties of PBZT and PBO fibers are briefly discussed. One limitation of the high-modulus polymeric fibers and ultrahigh-modulus carbon fibers in reinforced composites is their poor compressive strength. Issues related to the compressive strength of polymeric and carbon fibers are considered. 62 references, 7 figures, 4 tables.

Energy Technology Data Exchange (ETDEWEB)

Solid-state nuclear magnetic resonance (NMR) has been used to explore the nanometer-scale structure of Nafion, the widely used fuel cell membrane, and its composites. We have shown that solid-state NMR can characterize chemical structure and composition, domain size and morphology, internuclear distances, molecular dynamics, etc. The newly-developed water channel model of Nafion has been confirmed, and important characteristic length-scales established. Nafion-based organic and inorganic composites with special properties have also been characterized and their structures elucidated. The morphology of Nafion varies with hydration level, and is reflected in the changes in surface-to-volume (S/V) ratio of the polymer obtained by small-angle X-ray scattering (SAXS). The S/V ratios of different Nafion models have been evaluated numerically. It has been found that ...

Energy Technology Data Exchange (ETDEWEB)

Mixed microstructures have been studied in low- carbon microalloyed steels suitable for automotive applications, after continuous cooling from the hot-rolled condition. Microstructural features such as polygonal ferrite, bainitic and acicular ferrite and microphase constituent are identified using transmission electron microscopy. The influence of these mixed structures on the tensile strength, impact toughness and fracture behaviour is examined. It is found that improvements in impact toughness as compared with microalloyed medium- carbon ferrite/pearlite steels can be achieved from these predominantly acicular structures developed by controlling alloy composition and continuous cooling of these lower carbon steels. (orig.).

Energy Technology Data Exchange (ETDEWEB)

Self-consistent electronic structure calculations have been performed on two compositions of scandium sulfide ScS and Sc/sub 3/S/sub 4/. The results of the calculation of ScS are similar to those obtained for other transition metal chalcogenides and are in excellent agreement with heat capacity and reflectance measurements as well as UPS experiments. The calculation of the defect structure indicates the creation of sulfur p nonbonding states in metal-deficient ScS. The valency of the metal ions remains unchanged upon the creation of vacancies.

International Nuclear Information System (INIS)

Within the framework of a study on the chemical wear behaviour of sialon ceramics a range of compositions were prepared in which the alumina content was varied from 6 to 77 weight percent. The materials were hot-pressed from alumina and silicon nitride powders to a density of at least 97%. The structure and compositions of the phases occurring in these samples i.e. the O' phase, #beta#'-sialon solid solution and especially the X-phase were thoroughly characterized with respect to structure and composition using electron microprobe and transmission electron microscopy techniques. These results will be discussed in the light of earlier phase diagram studies. Some basic properties such as E-modulus and toughness were measured and related to microstructural features. E-modulus as well as toughness are at a minimum for materials with a high content of the X-phase. Oxidation of the ...

Science.gov (United States)

Titanium metal-matrix composites (MMC) are prime candidate materials for aerospace applications be-cause of their excellent high-temperature longitudinal strength and stiffness and low density compared with nickel- and steel-base materials. This article examines the steps GE Aircraft Engines (GEAE) has taken to develop an induction plasma deposition (IPD) processing method for the fabrication of Ti6242/SiC MMC material. Information regarding process methodology, microstructures, and mechani-cal properties of consolidated MMC structures will be presented. The work presented was funded under the GE-Aircraft Engine IR & D program.

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The compressive and bending strengths of a local tropical wood (Kapur-Dryobalanop sp.) were improved significantly by suitable impregnation of polymeric monomers (methylmethacrylate, methylmethacrylate - 5% dioxane and vinyl acetate) into the wood cellular structure and subsequent irradiation to form a wood-polymer composite. Statistical analysis revealed a linear relationship between increase in the strengths and the percentage of polymer impregnated. Fractographic analysis of the impact fractured surfaces under the scanning electron microscope showed the nature of the wood-polymer interface, which could account for the increase in the compressive and bending strengths. (author).

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Summary: The surface coverage of amorphous silica gels used in the synthesis of silica polyamine composites has been investigated by 29Si NMR. By diluting the polyamine anchor silane, chloropropyl trichlorosilane, with methyl trichlorosilane it was found that surface coverage could be markedly improved for a range of amine polymers after grafting to the silica surface. The commensurate decrease in the number of anchor points and increase in the number of free amines results in an increase in metal capacity and/or an improvement in capture kinetics. Solid state CPMAS-13C NMR has been employed to investigate the structure and metal ion binding of a series of these composite materials. It is reported that the highly branched polymer, poly(ethyleneimine) (PEI) exhibits much broader 13C NMR res...

British Library Electronic Table of Contents (United Kingdom)

Abstract A series of polypropylene carbonate (PPC)/ZnO nanocomposite films with different ZnO contents were prepared via a solution blending method. The morphological structures, thermal properties, oxygen permeability, water sorption, and antibacterial properties of the films were investigated as a function of ZnO concentration. While all of the composite films with less than 5 wt % ZnO exhibited good dispersion of ZnO in the PPC matrix, FTIR and SEM results revealed that solution blending did not lead to a strong interaction between PPC and unmodified ZnO. As such, poor dispersion was induced in the composite films with a high ZnO content. By incorporating inorganic ZnO filler nanoparticles, the diffusion coefficient, water uptake in equilibrium, and oxygen permeability decreased as the ...

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Zirconia has demonstrated a very moderate toughening effect in nitrogen-based ceramic composites because the reaction between tetragonal zirconia (t-ZrO_2) and nitrogen results in additional zirconia stabilization to a nontransformable t' or cubic structure. In O'-SiAlON matrices, the oxygen concentration increases and the oxygen-rich intergranular glassy phase prevents zirconia from nitridation. As a result, tetragonal ZrO_2 is maintained and is transformable in the O'-SiAlON materials. The present study has provided transmission electron microscopy (TEM) evidence of the zirconia transformation and the associated toughening effect in a ZrO_2/O'-SiAlON composite. The implications and limitations of the transformation on toughening of the material are discussed.

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Pulsed laser deposition (PLD) is known for its capacity to reproduce a target composition on a substrate. The authors have used this deposition technique to produce thin films of transition metal chalcogenides. However, the deposits were always deficient in Te relative to the starting material (composed by a refractory metal (niobium) and a chalcogene (tellurium)). Variations of the interreticular distances have been observed with respect to fluence and substrate temperature. The authors show that spatial composition of the films is determined by a degree of crystallinity of deposit and by the reaction of formation of Te{sub 2} molecule within laser induced plume. Two kinds of deposits have been obtained: Nb{sub 5}Te{sub 4}-type thin films which have a one-dimensional structure and NbTe{sub 2}-type thin films which have a two-dimensional structure. While NbTe{sub 2} films have been realized by ...

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This paper presents results of studying the thermo-transferred thermoluminescence (TTTl) phenomenon in potassium-yttrium double fluoride doped with terbium (K_2YF_5_:Tb) at different impurity concentrations (0.8%, 0.95% and 0.99%). Previously to study the TTTl phenomenon, structural characterization and chemical composition of the materials were determined. The structural studies were conducted using a scanning electron microscope; meanwhile, chemical composition was analyzed using energy dispersive X-ray spectroscopy. Thermoluminescence kinetics was studied irradiating the samples with "1"3"7Cs gamma rays as well as with "9"0Sr/"9"0Y beta rays, analyzing the glow curves by the deconvolution method for obtaining the kinetic parameters. (Author)

Science.gov (United States)

This paper deals with the experimental identification and the validation of a non-parametric probabilistic approach allowing model uncertainties and data uncertainties to be taken into account in the numerical model developed to predict low- and medium-frequency dynamics of structures. The analysis is performed for a composite sandwich panel representing a complex dynamical system which is sufficiently simple to be completely described and which exhibits, not only data uncertainties, but above all model uncertainties. The dynamical identification is experimentally performed for eight panels. The experimental frequency response functions are used to identify the non-parametric probabilistic approach of model uncertainties. The prediction of the low- and medium-frequency dynamical responses obtained with the stochastic system is compared with the experimental measurements.

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To investigate the variation in the fine structure of polyamide thin-film composite (TFC) membranes prepared via two different interfacial polymerization conditions (IP-I and IP-II), experiments on Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), water contact angle, and positron annihilation spectroscopy (PAS) coupled to a slow positron beam were conducted. Polyamide TFC membranes were prepared via the interfacial polymerization reaction between triethylenetetramine (TETA) and trimesoyl chloride (TMC) on the surface of a modified polyacrylonitrile (mPAN) membrane. Compared with the polyamide TFC membrane prepared via IP-I, the polyamide layer prepared via IP-II showed a shorter S plateau length (thinner thickness), a higher o-Ps intensity I3 value (higher free-volume con...

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The chemical composition and the semiconducting properties of passive films formed on nickel based alloy (Alloy 600) in acidic sulphate solution, pH 2.0 at room temperature were studied using Auger analysis, voltammetric techniques and the Mott-Schottky approach. The results obtained revealed that the presence of both chromium and mixed nickel-iron oxides in the films leads to the development of a p-n heterojunction, which controls their electronic structure, similarly manner to the case of stainless steels and Alloy 600 in borate buffer solution. This behavior has been interpreted as representing of an oxide system, which has a duplex character, with an inner p-type semiconducting region, mainly formed by chromium oxide and an outer n-type semiconducting region, containing iron oxide. It could also be observed that the nickel oxide present in the films acts as a barrier layer conferring improved protection.

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Graphical abstract: Ordered mesoporous organic-inorganic composite film has been achieved by sol-gel and spin-coating techniques. We believe that the mesoporous composite films have a potential application as a protect coating of bipolar plate material. Display Omitted Research highlights: ? Ordered mesoporous composite film was deposited on the 304 stainless steel. ? This composite film exhibited excellent protective performance in 0.5 M H_2SO_4. ? The film exhibited a high surface tension with water contact angle close to 90"o. - Abstract: The organic-inorganic composite film was deposited on the 304 stainless steel as bipolar plate material for proton exchange membrane fuel cells by spin-coating method. As shown by XRD, N_2 adsorption-desorption and TEM, the composite films exhibit ordered mesoporous structures. The corrosion tests in 0.5 ...

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IHI has developed a new Three-Dimensional Computer-Aided Design (3D-CAD) system to improve the design efficiency and quality of the steel structure of nuclear power plants. This system covers every design phase from the initial arrangement of structure to the production design sharing the same database. The system incorporates the design rules and professional expertise of designers, and enable easy and efficient design. The system can easily generate the three-dimensional data for structures, model data for stress analyses and composite arrangement data. The system has already been applied to several plants under construction and has achieved excellent results. The outline of the new CAD system is introduced. (author)

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Praseodymium-doped Bi_4Ti_3O_1_2 (BIT) with various compositions of dopant, Pr (x = 0.5, 0.6, 0.7, 0.8) in Bi_4_-_xPr_xTi_3O_1_2 (BPT) were synthesized using a low temperature wet chemical technique. Powders calcined at 800 deg. C exhibit a single phase polycrystalline perovskite bismuth-layered structure. Randomly oriented plate-like structures were observed under Scanning Electron Microscope (SEM). A small amount of Pr doping (x = 0.5) resulted in dramatically reduced of grain size from 2 #mu#m to less than 50 nm in which Pr plays the role as a grain growth inhibitor. However, by increasing the composition of Pr, bigger grain size of up to 1 #mu#m was observed for x = 0.8 that was caused by diffusion of Pr in the perovskite structure. Dielectric properties showed that dielectric permittivity decreased with the addition of x = 0.50, and increasing with further addition of Pr. ...

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This paper presents the first results on formation and study of structure and properties of micro- and nanocomposite combined coatings. By means of modeling the deposition processes (deposition conditions, current density-discharge, plasma composition and density, voltage) we formed the three-layer nanocomposite coatings of Ti-Al-N/Ti-N/Al_2O_3. The coating composition, structure and properties were studied using physical and nuclear-physical methods. The Rutherford proton and helium ion backscattering, scanning electron microscopy with microanalysis, grazing incidence X-ray diffraction, as well as nanohardness tests (hardness) were used. Measurements of wear resistance and corrosion resistance in NaCl, HCl and H_2SO_4 solutions were also performed. For testing mechanical properties such characteristics of layered structures as hardness H, elastic modulus E: H"3/E"2 etc. were ...

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New data about the structure of high-temperature resistant metalloceramic plasma sprayed coatings in micro and nano areas are presented. Application of the new instrumental methods: transmission electron microscopy combined with selected area electron diffraction mode is possible to obtain these data. The first layer in Ni based metallic bond coat shows nanocrystalline structure. External ceramic layer based on stabilised ZrO_2 is polycrystalline and contains both cubic and tetragonal crystalline phases. Local inhomogeneities in coatings phase composition are determined. (author)

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The surface coverage of amorphous silica gels used in the synthesis of silica polyamine composites has been investigated by 29Si NMR. By diluting the polyamine anchor silane, chloropropyl trichlorosilane, with methyl trichlorosilane it was found that surface coverage could be markedly improved for a range of amine polymers after grafting to the silica surface. The commensurate decrease in the number of anchor points and increase in the number of free amines results in an increase in metal capacity and/or an improvement in capture kinetics. Solid state CPMAS-13C NMR has been employed to investigate the structure and metal ion binding of a series of these composite materials. It is reported that the highly branched polymer, poly(ethyleneimine) (PEI) exhibits much broader 13C NMR resonances than the linear polymers poly(allylamine) (PAA) and poly(vinylamine) (PVA). These results are understood in terms of the low energy ...

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An experiment was conducted on the structure of mesoscopic calculating method for cement-based composite materials. The purpose was utilization for the simulation of mesoscale failure processes and the development of new composite materials. Mesh split based on Voronoi polygons was applied as the discrete limit analysis of the cement-based composite materials containing aggregate particles taking the arrangement of random particles into consideration, and a two-dimensional rigid-body/spring model was employed as the model. The nonhomogeneity of concrete was represented by three kinds of different spring parameters which were aggregate, mortar matrix and their interfaces. The simulation results were summarized as follows: The stress-strain curve went into a non-linear state from the 30% of the maximum stress. The generation of interfacial crack started on the side of the aggregate, but the propagation of ...

Science.gov (United States)

Silanization of the silica gel surface in the synthesis of silica gel polyamine composites uses (chloropropyl)-trichlorosilane (CPTCS). It is possible to substitute a molar fraction of reagent CPTCS with methyltrichlorosilane (MTCS), creating a mixed silane surface layer. Two types of silica gels were modified with a series of MTCS:CPTCS molar ratios. Solid-state CP/MAS 29Si and 13C NMR spectroscopies were used to evaluate the surface silane composition. Surface silane coverage was markedly improved for the resulting gels. When polyamines were grafted to the resultant MTCS:CPTCS silane layers, it was shown that the decrease in the number of propyl attachments to the polyamine resulted in increased quantities of ''free amines''. Optimum MTCS:CPTCS ratios were determined for three polyamines grafted onto one silica gel. A substantial free amine increase was observed for poly(allylamine) (PAA). Metal uptake ...

Science.gov (United States)

With an increased use of fiber reinforced concrete in structural applications, proper characterization techniques and development of design guides are needed. This dissertation presents a multi-scale modeling approach for fiber and fabric reinforced cement-based composites. A micromechanics-based model of the yarn pullout mechanism due to the failure of the interfacial zone is presented. The effect of mechanical anchorage of transverse yarns is simulated using nonlinear spring elements. The yarn pullout mechanism was used in a meso-scale modeling approach to simulate the yarn bridging force in the crack evolution process. The tensile stress-strain response of a tension specimen that experiences distributed cracking can be simulated using a generalized finite difference approach. The stiffness degradation, tension stiffening, crack spacing evolution, and crack width characteristics of cement composites can be derived using ...

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By dissolution of iron (2) carbonate in rhenium acid iron (2) perrhenate of the Fe(ReO/sub 4/)/sub 2/x4H/sub 2/O composition is obtained. By the method of thermal analysis the limits of tetra-, dihydrate and anhydrous iron (2) perrhenate stability are revealed. By means of X ray phase and IR spectroscopic analysis methods modification of structure in the process of synthesized salt dehydration is shown.

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This book presents the papers given at a conference on offshore platforms. Topics considered in this book include risk assessment, crack propagation, fracture control, stress corrosion, the reliability of pile foundations, the thermal conductivity of offshore pipeline coating material, economic analysis, hydrodynamics, simulation, Arctic structure design, composite materials, buoys, deep water drilling, corrosion protection, pollution control equipment, and subsea exhaust gas compressors.

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This paper describes phase-retrieval approaches in music by focusing on the particular case of the cyclic groups (beltway problem). After presenting some old and new results on phase retrieval, we introduce the extended phase retrieval for a generalized musical Z-relation. This concept is accompanied by mathematical definitions and motivations from computer-aided composition. We assume from the reader basic knowledge of groups, topological groups, group algebras, group actions, Lebesgue integration, convolution products, and Fourier transform.

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A systematic study of structure-mechanical properties relation is reported for MoSi{sub 2}-SiC nanolayer composites. Alternating layers of MoSi{sub 2} and SiC were synthesized by DC magnetron and rf-diode sputtering, respectively. Cross-sectional transmission electron microscopy was used to examine three distinct reactions in the specimens when exposed to different annealing conditions: Crystallization and phase transformation of MoSi{sub 2}, crystallization of SiC, and spheroidization of the layer structures. Nanoindentation was employed to characterize the mechanical response as a function of structural changes. As-sputtered material exhibits amorphous structures in both types of layers and has a hardness of 11 GPa and a modulus of 217GPa. Subsequent heat treatment induces crystallization of MoSi{sub 2} to form the C40 structure at 500C and SiC to form the a ...

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... 300710+Ceramic+Transactions+Series 2120%28Series+Code%29+Ceramic+Transactions+Series Wiley::Ceramic Transactions Series WILEY KNOWLEDGE FOR GENERATIONS United States Change Location Home ...CART | MY ACCOUNT | CONTACT US | HELP Home / Engineering & Materials Science / Materials Science / Ceramic Transactions Series Related Subjects Soft Matter Organic Electronics Structural Materials, ... Ceramics Structural Materials, Composites Structural Materials or Construction Materials Corrosion Electronics Materials Related Series Ceramic Engineering and Science Proceedings Wiley Series in Materials ...for Electronic and Optoelectric Applications Ceramic Transactions (CTs) books contain papers presented at the Annual Meeting of the American Ceramic Society, ...

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Collection, analysis and quantification of human factor data are important compositions of human reliability analysis (HRA) and probabilistic risk assessment (PRA). Various human factor databases have been set up, but there are comparatively little human factor data management systems which can be uses for collection, classification, analysis, calculation and predication of the human factor data. Therefore, the human factor data management system for Daya Bay NPP is developed, with the following three modules and four databases: original data module, computing module, introduced data module, and basic database, other data source of the plant, external database and introduced database. The foundational problems about human factor data and the systemic structure and function are described. The data structure in the database is also discussed, because it is of the most importance in the system

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Titanium oxides were grown anodically to selected final potentials on grade II polycrystalline titanium under different anodization rates. XPS and RBS results show that the oxide consists of primarily TiO2 with a non-stoichiometric oxide/metal interface, with the slower growth rate associated with a thicker layer at the interface. Characterization using TEM reveals that the structure of the oxide evolves from a primarily amorphous phase to islands of crystallites in an amorphous matrix, to an entirely crystalline phase by increasing the polarization potential. Slower growth rates tend to remain crystalline at higher potentials. The mechanical strength of oxide films extracted from load-depth data by nanoindentation varies dramatically for oxide films grown by different rates at 9.4 V, and to a lesser extent at lower potentials. The variation of film strength is associated with both compositional and structural ...

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This work proposes an acoustic structure feasible to engineer that accomplishes the requirements of acoustic cloaking design recently introduced by Cummer and Schurig (2007 New J. Phys. 9 45). The structure, which consists of a multilayered composite made of two types of isotropic acoustic metamaterials, exactly matches the conditions for the acoustic cloaking. It is also shown that the isotropic metamaterials needed can be made of sonic crystals containing two types of material cylinders, whose elastic parameters should be properly chosen in order to satisfy (in the homogenization limit) the acoustic properties under request. In contrast to electromagnetic cloaking, the structure here proposed verifies the acoustic cloaking in a wide range of wavelengths; its performance is guaranteed for any wavelength above a certain cutoff defined by the homogenization limit of the sonic crystal employed in its ...

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It has been shown by recent experiments that bulk immiscible metals (e.g. Ag/Cu, Ag/Co and Au/Ni) can form binary alloys on certain surfaces where the substrate mediates the elastic misfits between the two components, thus relieving the elastic strain in the overlayer. These novel surface alloys exhibit a rich phase structure. We formulate a two-component Frenkel-Kontorova model in one dimension to study surface alloy formation. This model can naturally incorporate dislocation formation that plays a crucial role in determining the actual structure of the system. Using energy minimization calculations we provide a phase diagram in terms of average alloy composition and the energy of mixing. Monte Carlo simulations were also performed to study the structure and interaction of the emerging dislocations.

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AlGaInP epitaxial layers grown at 690 degree C by atmospheric pressure organometallic vapor phase epitaxy are investigated by transmission electron microscopy. For the first time, compositionally modulated and ordered structures are simultaneously observed in AlGaInP alloys. The ordering is of the CuPt type with ordering along the #left brace#111#right brace# directions. The ordered regions appear as plate-like microdomains, while the composition modulation takes the form of a fine columnar constrast oriented along the growth direction. In addition, from the results of (001) plan-view diffraction contrast examination, the principal strain direction associated with the modulation structures is found to be perpendicular to the growth direction and lies in the surface plane. Thus, it is concluded that the spinodal decomposition is initiated and developed on the surface during the growth of the AlGaInP ...

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Modelization of crack propagation and theoretical prediction of rupture are the two main objectives of researchers in stress corrosion cracking. Nevertheless, to reach this aim, the behavior of the passive film which appears spontaneously on the substrate in contact with an environment has to be known. This structural and mechanical characterization is all the more difficult because the number of parameters is important: crystallinity rate, defects concentration, thickness (about a few nanometers), electric field, chemical composition (a lot of oxides are present), peeling layers (atomic structure for example) and some hypothesis can be made about their multi-layer structure, their chemical composition or their epitaxial character... Passive films formed on 316L or 304L stainless steels in different aqueous solutions (in ambient air, in MgCl{sub 2} at 117 deg. C...) have been ...

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Mono-dispersed cubic CeO{sub 2} nanoparticles have been synthesized using a surfactant-assisted method with laurylamine hydrochloride and cerium alkoxide modified with acetylacetone in an aqueous solution system. The prepared cubic CeO{sub 2} nanoparticles had a highly crystallized structure at 353 K and formed rod-like structures by calcination at 673 K after freeze-drying the CeO{sub 2} gel. We discovered a clear potential to make 1D, 2D or 3D CeO{sub 2}-materials with a well-controlled characteristic length and shape by assembling cubic-shaped CeO{sub 2} nanoparticle building blocks. CeO{sub 2}-TiO{sub 2} composite nanostructures have also been synthesized by changing the mole ratio of cerium alkoxide/titanium alkoxides. By utilizing the redox characteristic of CeO{sub 2}, CeO{sub 2} nanoparticles and CeO{sub 2}-TiO{sub 2} composite nanostructures after calcination, showed reaction activity toward ...

Science.gov (United States)

Polymer matrix composites are presently used in many fields due to their excellent mechanical properties such as high specific strength and stiffness. However, not much is known of these composites' response to impact loading, which usually occurs at strain rates much higher than the strain rates used to measure the quasi-static mechanical properties of materials. The use of static properties in the study of structures that undergo dynamic loading can produce excessive design weight or cause unexplained and untimely failure. The studies included in this dissertation provide the results of Split Hopkinson Pressure Bar experiments to determine the ultimate compressive strength and strain of composites at high strain rates. Most researchers are using specimens with different dimensions and geometry. For this reason, it is difficult to compare results of tests done by different people. Herein, the Split ...

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Very good friction and wear measurements are reported for MRCC (metal reinforced carbon composites), made from low-wear non-graphitic carbon matrix with metal-fiber reinforcement. Counterfaces include austenitic and martensitic stainless steels, Si nitride, and alumina. Effects of high load, high temperature, and gaseous environments are reported: removal of humidity, atm. oxygen have little effect on friction, wear for MRCC sliding against ceramic or stainless steel. Wear of Al oxide riders on MRCC is very low, not affected by contact load. 260 C temperatures do not degrade performance of 440-C riders on MRCC disks or raise friction. In small or large sizes, MRCC is made in a single-pass process for about the same volume cost as cast iron. It can survive heating in nitrogen above 1600 C without loss of integrity or major change of dimensions.

British Library Electronic Table of Contents (United Kingdom)

In allusion to the explosion of a urea reactor took place in a fertilizer plant at Pingyin, Shandong, China, a series of evidence collection and inspection jobs which includes collecting operation condition and parameters, sampling the explosion fracture, reactor body apart from explosion fracture, and leak detection medium and its hangover, etc., had been carried out firstly. Based on these jobs, farther analysis and computation work has been done to the structural and materials characteristics and the operation condition of the urea reactor, including compositions, metallographic phases, tensile properties, impact energy, strain ageing characteristics, and fracture toughness of the urea reactor steels, the compositions of leak detection medium and its hangover in the urea reactor, and ex...

British Library Electronic Table of Contents (United Kingdom)

The factors affecting the rate of silica leaching in alkaline aqueous media from surface silanized, nanoporous, amorphous, silica gels and from silanized silica gels that have been modified with polyamines to form the previously reported silica polyamine composites (SPCs), BP-1 and BP-2 have been investigated. Silanization with alkyl trichlorosilanes slows the rate of silica leaching relative to the unmodified silica gels. The use of bulkier aryl silanes somewhat decreases the silica leaching under the same conditions. Interestingly, after modification of the silanized silica with poly(allylamine) (PAA) to make BP-1, the leaching increases, but subsequent modification of the SPC with chloroacetic acid to make BP-2, quenches this increase. A mechanism explaining these results is discussed. ...

International Nuclear Information System (INIS)

The thermal transformation of Al-base icosahedral phases was studied in-situ by real time neutron powder diffraction. Different compositions have been selected in order to vary the initial phase morphology and change the neutron scattering contrast between species. Alloys with low silicon and large aluminium contents produce first the orthorhombic O-Al_6Mn modification. In alloys with larger silicon content, the #alpha#-AlMnSi cubic phase appears soon after the beginning of the transformation but is still preceeded by O-Al_6Mn. Depending on compositions, the crystallization of the icosahedral phase is controlled either by the diffusion of Al through its interface with the residual fcc aluminium or that of Si within the bulk. The results are discussed in the light of current structural models. (author) 40 refs., 14 figs., 3 tabs.

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Photocurrent and capacitance measurements of semiconductor passive films formed on metals and alloys can be used to study the electronic properties and reveal indirect information about structure and composition. The current work used these techniques to investigate the electronic properties of the passive films formed on three austenitic stainless steels, types 304L, 316L and 254SMO, in borate. Evidence was found for the existence of a large number of localised mid bandgap states, consistent with amorphous oxides. However, the flat-band potentials of the austenitic stainless steel passive films were found to be independent of both composition and measuring frequency. The most credible explanation for the bandgap values determined from photocurrent measurements is that the passive films are formed as dual layers, iron oxide outer layer and chromium oxide inner layer. This model does not need to evoke the potential dependent ...

International Nuclear Information System (INIS)

In connection with the different cyclical strengths of the two-phase (#alpha# + #beta#) titanium alloy in the case of the acicular and rounded formations of the #alpha#-phase, we have studied, employing the X-ray diffraction method, the phase composition of the alloy and the influence of heat treatment upon it. Using the method of electronic fractography, we examined the fractures in samples destroyed by the asymmetric twisting, in order to find out why the durability of the alloy is dependent upon the #alpha# - phase structure. It has been found that in the BT22 alloy, the decay the #beta#-phase may proceed in two ways; either with the formation of the martensite #alpha#'-phase of the acicular shape or with the separation of the non-martensite round-shaped #alpha#-phase. The character of the phase transformations #beta# - #alpha# or #beta#-#alpha#' is, to a considerable extent, the conseguence of the prehystory of the alloy and is dependent ...

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Complex I (NADH:ubiquinone oxidoreductase) is the largest enzyme of the mitochondrial respiratory chain. Compared to its bacterial counterpart which encompasses 14-17 subunits, mitochondrial complex I has almost tripled its subunit composition during evolution of eukaryotes, by recruitment of so-called accessory subunits, part of them being specific to distinct evolutionary lineages. The increasing availability of numerous broadly sampled eukaryotic genomes now enables the reconstruction of the evolutionary history of this large protein complex. Here, a combination of profile-based sequence comparisons and basic structural properties analyses at the protein level enabled to pinpoint homology relationships between complex I subunits from fungi, mammals or green plants, previously identified...

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The thermal stability and deformability of Mn-Al-C alloys containing 0.6 pct C are investigated experimentally as a function of excess phase content. It is shown that an increase in Mn content from 68.9 to 73.5 pct leads to increased stability of the high-temperature epsilon phase. The enrichment of the system Mn-Al-Cu in Mn and Al above the optimum composition leads to the formation of nonmagnetic excess phases, eta and beta, which reduce the magnetization of the alloy. In addition, a decrease in thermal stability is observed in the alloy with 73.5 pct Mn due to the decomposition of the ferromagnetic phase. 7 references.

International Nuclear Information System (INIS)

We studied the influence of alloying on the structural and electronic properties of the unrelaxed and relaxed Si_1_-_yC_y random alloys by means of ab initio theoretical calculations using two methods: (i) a supercell approach in connection with the plane-wave pseudopotential method; (ii) the full-potential augmented plane-wave plus local orbitals (APW+lo) method. The first method is used to obtain the relaxed atomic structure. The relaxed atomic positions obtained by pseudopotential calculations were used to calculate the band structure via the second method. The local density approximation was used for the exchange and correlation energy density functional. We investigated the lattice parameters and band gap energies. We found that a quite smaller gap appears in the neighborhood of y=0.03125 concentration of C atoms. The band gap shows a large anomalous bowing and is strongly composition dependent. ...

Science.gov (United States)

This paper describes the design of a test rig, which is used to apply a representative pressure load to a full-scale composite sandwich secondary aircraft structure. A generic panel was designed with features to represent those in the composite sandwich secondary aircraft structure. To provide full-field strain data from the panels, the test rig was designed for use with optical measurement techniques such as thermoelastic stress analysis (TSA) and digital image correlation (DIC). TSA requires a cyclic load to be applied to a structure for the measurement of the strain state; therefore, the test rig has been designed to be mounted on a standard servo-hydraulic test machine. As both TSA and DIC require an uninterrupted view of the surface of the test panel, an important consideration in the design is facilitating the optical access for the two techniques. To aid the test rig design a ...

International Nuclear Information System (INIS)

Allyl alcohol (AA), acrylonitrile (AN), methyl methacrylate (MMA), monomers and monomer mixtures AA+AN, AA+MMA were used to conserve and consolidate Beech and Spruce. After impregnation, copolymerisation and polymerisation were accomplished by gamma irradiation. The fine structure of wood+polymer(copolymer) composites was investigated by Scanning Electron Microscopy (SEM). It was observed that copolymer obtained from AA+MMA monomer mixture showed the optimum compatibility. The compressional strength and Brinell Hardness Numbers determined for untreated and treated wood samples indicated that the mechanical strength of wood+copolymer composites was increased. It was found that the mechanical strength of the wood samples containing the AA+MMA copolymer was higher than the others. In the presence of P(AA/MMA), at highest conversion, the compressive strength perpendicular to the fibres in Beech and Spruce increased ...

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The reactions between (100) GaAs and the near-noble metals Ni, Pd, and Pt have been investigated by application of high-resolution transmission electron microscopy (TEM), energy-dispersive analysis of x rays in the scanning TEM and Rutherford backscattering spectrometry. Emphasis is placed on the evolution of the phase distributions, film compositions, and interface morphologies during annealing at temperatures up to 480 /sup 0/C. The first phase in the Ni/GaAs reaction is shown to have the nominal composition Ni/sub 3/GaAs. Ternary phases of the type Pd/sub x/GaAs are also found to be the dominant products of the Pd/GaAs reaction. Conversely, only binary phases result from the Pt/GaAs reaction. These observations are used to construct isothermal sections of the M--Ga--As thin-film phase diagrams. The behavior of a thin (1--2 nm) native oxide--hydrocarbon layer during the Ni/GaAs, Pd/GaAs, and Pt/GaAs reactions is also investigated. Only the ...

International Nuclear Information System (INIS)

Angelin Pedra is a specie found in the north of Mato Grosso State in Brazil, where an expressive volume of waste of this wood is produced. An alternative to recycle this waste is to produce wood plastic composites. However, structural and chemical investigations are fundamental to generate information for this use. In the present work, low field NMR was used to determine the spin-lattice and spin-spin relaxation times with objective to investigate the molecular dynamic behavior of the alburnu and cerne regions of Angelin Pedra aiming at a potential use of this waste wood in polymeric composites. The results of the proton spin-lattice relaxation time (T1H) and the proton spin-spin relaxation time (T2H) showed at least three different mobility domains for both regions. Among the values, one was very flexible and other was rigid. Knowing that wood is a polymer composite basically constituted by cellulose, ...

Energy Technology Data Exchange (ETDEWEB)

In case of airplane engine, technical development like increase of temperature at the turbine entrance or high speed rotation with a purpose of thrust up, and reduction of structural part single substance mass or reduction of number of parts in order to achieve lightness and so forth, has been promoted in order to improve the performance that is evaluated by thrust weight ratio (thrust/weight). Accordingly, research and development of high heat resistance, high strength, lightness and so forth of each material of the parts are in demand. As a representative material corresponding to such demand, L10 type {nu}-TiAl intermetallic compound which is light and has improved high temperature strength properties is paid attention and its development is promotes. The authors were successful for the first time in the world to manufacture composite material with CVD type SiC fiber that was difficult so far by using TiAl-Cr alloy having super plasticity at ...

International Nuclear Information System (INIS)

The development of Callossobruchus chinensis (L.) in different packaging materials were conducted with gram and lentil seeds under control temperature. The highest population rise was recorded in laminated jute bags and the weight loss of gram increased with the increase of the number of insects. A doses of 0.1 kGy inhibit all metamorphic stages of the beetle. The use of appropriate packaging materials can reduce the risk of re infestation in the post-irradiated food items. 9 refs., 1 fig., 2 tables (author).

International Nuclear Information System (INIS)

Lab scale mulch biofilm barriers were constructed and tested to evaluate their performance for preventing the migration of aqueous and surfactant solubilized PAHs. The spatial distribution of viable PAH degrader populations and resultant biofilm formation were also monitored to evaluate the performance of the biobarrier and the prolonged surfactant effect on the PAH degrading microorganism consortia in the biobarrier. Sorption and biodegradation of PAHs resulted in stable operation of the system for dissolved phenanthrene and pyrene during 150 days of experimentation. The nonionic surfactant could increase the solubility of phenanthrene and pyrene significantly. However, the biobarrier itself couldn't totally prevent the migration of micellar solubilized phenanthrene and pyrene. The presence of surfactant and the resultant highly increased phenanthrene or pyrene concentration didn't appear to cause toxic effects on the attached biofilm in the biobarrier. However, the presence of ...

Science.gov (United States)

Mg-Al mixed oxides with Mg/Al molar ratios of 0.5--9.0 were obtained by thermal decomposition of precipitated hydrotalcite precursors. The effect of composition on structure and surface and catalytic properties was studied by combining several characterization methods with ethanol conversion reactions. The nature, density, and strength of surface basic sites depended on the Al content. The catalyst activity and selectivity of Mg-Al mixed oxides in ethanol conversion reactions depended on composition. The dehydrogenation of ethanol to acetaldehyde and the aldol condensation to n-butanol both involved the initial surface ethoxide formation on a Lewis acid-strong base pair. The dehydration of ethanol to ethylene, and the coupling and dehydration to diethyl ether increased with Al content, probably reflecting the density increase of both Al{sup 3+}-O{sup 2{minus}} pairs and low- and medium-strength basic sites. Pure Al{sub ...

Energy Technology Data Exchange (ETDEWEB)

Safety and environmental assessments have been made of conceptual fusion power plant designs employing silicon carbide composites (SiC/SiC) as the first wall and blanket structure material. These have used similar analysis methods to earlier studies of designs based on vanadium alloy or low-activation martensitic steel, allowing direct comparisons. The very low short-term activation of silicon carbide results in an almost insignificant level of decay heat in postulated loss of coolant accidents, and a lower {gamma}-dose rate on the timescale of relevance to handling for maintenance operations. However on the longer time-scale, of interest in possible recycling operations, decommissioning and waste management, SiC/SiC appears to perform no better than vanadium alloy or low-activation martensitic steel, due in part to the activation of impurities in a realistic composition. Furthermore, its increased neutron transparency may ...

Energy Technology Data Exchange (ETDEWEB)

When a metallic alloy is quenched into a miscibility gap, a mixture of two phases develops, whose domain structure then coarsens because of the interfacial energy between the two phases. This spatial arrangement of the domains and the rate at which they evolve may be strongly influenced by elastic interactions. In a recent paper, the authors described a method for simulating the effect of anisotropic elastic interactions in a two-dimensional Ising model of a cubic alloy, using Kawasaki dynamics with the elastic interactions represented by a long-range two-body interaction potential. Here they present the results of such simulations at various temperatures, alloy compositions and misfits (by misfit they mean the difference in size between the two kinds of atom), exhibiting snapshots both of the microscopic configurations (corresponding to experimental measurements using transmission electron microscopy) and of their squared Fourier transforms ...

Energy Technology Data Exchange (ETDEWEB)

The origin of natural gas in the Japanese oil and gas fields are geochemically studied. Samples are taken from structural natural gas, surface gas seepage, water-dissolved natural gas and coal-field gas of the Japan Sea coast area. The origins of primary hydrocarbons are classified into bacteria gas and thermogenic gas, the latter being subclassified into gas in oil production zone with the per million deviation of the carbon isotope (/sup 13/C/sup 1/) of methane less than -35 and those gases with maturity higher than this. Surface gas seepage is subjected to migration and bacterial oxidation. Coal gas is similar to oil gas. The CO/sub 2/ concentration is 0 - 2% and /sup 13/CO/sub 2/ deviations from -30 - +30. The origin can be barely estimated from the isotopic composition because of the wide secondary change in the composition. The origin and migration of gas from the gas field of northern Niigata are not similar to those ...

International Nuclear Information System (INIS)

SiC-AlN and SiC-SiAlON refractory composites were obtained by means of nitridation of the mixtures of silicon carbide (SiC) powder with a broad granulometric distribution and powders of aluminium (Al) and aluminium-silicon (Al-Si) mixtures. The mixtures of the composition Al-25% Si, Al-50% Si and Al-75% Si were previously prepared by means of 'mechanical alloying' technique. Thermodynamic analysis was accomplished in order to evaluate the viability of SiC-SiAlON and SiC-AlN refractories production by the chosen processing method, and the results confirmed viability of such. Investigation of nitridation of Al and Al-Si powder compacts in order to obtain the AlN and #beta#-SiAlON matrix phases of the composite was accomplished by means of differential thermal analysis (DTA) and thermogravimetric analysis (TG). The results of the thermal analysis show that nitridation of the Al-25% Si, Al-50% Si and Al-75% Si resulting in ...

International Nuclear Information System (INIS)

This study demonstrates amplified spontaneous emission (ASE) of the ultraviolet (UV) electroluminescence (EL) from ZnO at #lambda##approx#380 nm in the n-ZnO/ZnO nanodots-SiO_2 composite/p- Al_0_._1_2Ga_0_._8_8N heterojunction light-emitting diode. A SiO_2 layer embedded with ZnO nanodots was prepared on the p-type Al_0_._1_2Ga_0_._8_8N using spin-on coating of SiO_2 nanoparticles followed by atomic layer deposition (ALD) of ZnO. An n-type Al-doped ZnO layer was deposited upon the ZnO nanodots-SiO_2 composite layer also by the ALD technique. High-resolution transmission electron microscopy (HRTEM) reveals that the ZnO nanodots embedded in the SiO_2 matrix have diameters of 3-8 nm and the wurtzite crystal structure, which allows the transport of carriers through the thick ZnO nanodots-SiO_2 composite layer. The high quality of the n-ZnO layer was manifested by the well crystallized lattice image in the ...

International Nuclear Information System (INIS)

This paper reports the results of a fine-probe EDS microanalytical study of cellular precipitation in a Cu-Ti binary alloy. Compositional profiles across the solute depleted Cu-rich FCC lamellae and the Cu_4Ti lamellae within isothermally formed cellular colonies were measured in a FEG-TEM from thin-foil specimens prepared by conventional electropolishing and by a technique using a Ga"+ focused ion-beam (FIB). The Cliff-Lorimer ratio method, with an absorption correction, was employed to quantify the compositions. Two FIB samples were prepared with different orientations of the lamellae with respect to the ion-milling direction. The compositional profiles across the Cu-rich FCC lamellae and the Cu_4Ti compound lamellae in both the FIB-prepared samples and the electropolished sample were, within experimental error, numerically equivalent. The composition of the Cu_4Ti compound phase lamellae was very ...

Energy Technology Data Exchange (ETDEWEB)

Reinforced (heterogel) silicate materials containing an amorphous and a crystalline phase are being used more and more industry. Such systems are energetically unsaturated and therefore promising for use in catalysts. The authors used two reinforced materials as supports: an aluminosilicate containing a zeolite (the cracking catalyst, tseokar) and asbestos-containing aluminosilicate. The active component was introduced by impregnation, and this was followed by heat treatment during which the chemical composition and porous structure were formed. The impregnating mixture consisted of solutions of potassium sulfate and vanadate of the required concentrations. The testing shows that reinforced heterogel systems are promising as support materials for sulfuric acid catalysts.

International Nuclear Information System (INIS)

We explore the relation of nanostructures with the appearance of giant magnetoresistance (GMR) in melt-spun CuCo ribbons. We find by energy-filtered transmission electron microscopy that the ribbons are composed of a periodic distribution of Co within the Cu, as in spinodal decomposition. The lamellar structure should thus be associated with GMR, as only a small percentage of the Co is present in the form of grains. This is counterintuitive, for no clear interfaces are present as required by standard models, and the period of the composition oscillation (43-52 nm) is an order of magnitude larger than the mean free paths for electrons. Upon annealing, a secondary spinodal decomposition appears following the same direction as the original.

Energy Technology Data Exchange (ETDEWEB)

Electron energy loss (EEL) spectroscopy and high angle annular dark field (HAADF) imaging in aberration-corrected electron microscopes are powerful techniques to determine the chemical composition and structure of materials at atomic resolution. We have implemented Smart Acquisition, a flexible system of scanning transmission electron microsocpy (STEM) beam position control and EELS collection, on two aberration-corrected dedicated cold field emission gun (FEG) STEMs located at SuperSTEM, Daresbury Laboratory. This allows the collection of EEL spectra from spatially defined areas with a much lower electron dose possible than existing techniques such as spectrum imaging.

International Nuclear Information System (INIS)

Using the slow electrons spectrometer one can get information on the surface structure, its element composition, chemical bonds, adsorption phenomena, electron state density and surface oscillation. We have developed the methods and created the apparatus that makes it possible to investigate the electron backscattering by solid surface. We have studied the electron scattering by the polycrystalline and monocrystalline. GaAs surface in the energy range of 0 to 9 eV. The FWHM of electron energy distribution function was 70 meV. (author).

International Nuclear Information System (INIS)

Production of titanium alloys from the mixture containing large amounts of metallurgy wastes is very promising. It is shown that unlimited possibilities of the waste material use in the mixture (up to 100%) are provided by garnissage melting, the size of the cast being limited only by that of the vessel. With garnissage being used as a consumed electrode the metal is refined from hydrogen and the blank ingots to serve as consumed electrodes in electro-slag remelting are chemically homogeneous. The ingots thus obtained have dense structure, rather fine grain homogeneous chemical composition, are no less pure than those obtained by vacuum arc remelting and provide for economic savings.

Science.gov (United States)

Continuous wave lasing operation with the shortest wavelength for semiconductor lasers was obtained from AlGaInP double heterostructure lasers at 77 K. The structure was grown by metalorganic vapor phase epitaxy. Lasing wavelength was 583.6 nm (yellow). Threshold current was 43 mA (1.9 kA/cm/sup 2/). Magnesium was adopted as a p-type dopant, and was proved to be preferable for a high aluminum composition AlGaInP cladding layer.

Energy Technology Data Exchange (ETDEWEB)

Density oscillations induced by MHD activities were observed in NBI heated plasmas on CHS by using an HCN laser interferometer. The accompanied changes of the density profiles were also observed. The oscillations are composition of m=0 sawteeth like crash and m=2 sinusoidal oscillations as a post courser of the crash. Possible models of the oscillation structure are examined in order to explain experimental data of the interferometer. Rotating plasma core, which is hollow profile and keeps constant elongation of the flux surface can explain amplitude and phase distribution of the sinusoidal oscillation. (author)

International Nuclear Information System (INIS)

In the present work, using a pad-on-disc-type wear tester, the tribological properties of the pad next to the disk made of cast iron were investigated with changing the substance of the components. As well, micro-structural characterisation of braking pads was performed using scanning electron microscopy and also temperature outcome of the pads was examined at the temperatures of 50-400 "oC in the pressure of 1050 and 3000 kPa. Finally, the effect of environment to the pads was studied in water, salty water, oil and braking liquid media.

Energy Technology Data Exchange (ETDEWEB)

The aim of our research was to identify structures and chemical compositions of phases formed during internal oxidation of multi-component Ag-Zn-Mg-based alloys. Since the ability of inoculation mostly depends on large free energy of formation of oxides of microalloying elements and their crystallographic similarity, Mg in quantities of 0.001-0.5 mass% was selected as a micro-alloying element. These correspond to the quantities of 0.005-2.5 vol.% of MgO in the selected Ag-Zn-based alloys. Ag-based metal matrix, heterogeneous nuclei of MgO and oxide (ZnO) of the main alloying element were analysed by transmission electron microscopy (TEM). Structural inter-connections among them were also investigated and analysed. In situ phenomenon of heterogeneous nucleation of MgO and ZnO was proved. (orig.)

Scientific Electronic Library Online (English)

Abstract in english Structural characterisations using the SAXS technique in a number of nanoheterogeneous materials and liquid solutions are reviewed. The studied systems are protein (lysozyme)/water solutions, colloidal ZnO particles/water sols, nanoporous NiO-based xerogels, hybrid organic-inorganic siloxane-PEG and PPG nanocomposites and PbTe semiconductor nanocrystals embedded in a glass matrix. These investigations also focus on the transformations of time-varying structures and on str (more) uctural changes related to variations in temperature and composition. The reviewed investigations aim at explaining the unusual and often interesting properties of nanostructured materials and solutions. Most of the reported studies were carried out using the SAXS beamline at the National Synchrotron Light Laboratory (LNLS), Campinas, Brazil.

Energy Technology Data Exchange (ETDEWEB)

A number of materials of composition YSr{sub 2}Cu{sub 3-x}MxO{sub 7{+-}y} with M = Ti, Fe, Co, Al, Ga and Pb were prepared by solid state reactions. They belong to the tetragonal P4/mmm space group and their unit cell parameters were determined and refined from X-ray powder data. The infrared spectra of the compounds were also recorded and are briefly discussed on the basis of their structural characteristics and by comparison with those of related materials. (orig.) 23 refs.

British Library Electronic Table of Contents (United Kingdom)

Abstract Development of inhibitors and vaccines that mitigate rumen-derived methane by targeting methanogens relies on knowledge of the methanogens present. We investigated the composition of archaeal communities in the rumens of farmed sheep (Ovis aries), cattle (Bos taurus) and red deer (Cervus elaphus) using denaturing gradient gel electrophoresis (DGGE) to generate fingerprints of archaeal 16S rRNA genes. The total archaeal communities were relatively constant across species and diets, and were less variable and less diverse than bacterial communities. There were diet- and ruminant-species-based differences in archaeal community structure, but the same dominant archaea were present in all rumens. These were members of three coherent clades: species related to Methanobrevibacter ruminan...

International Nuclear Information System (INIS)

Passive films formed on Alloy 690 in different pH solutions at high temperatures were studied by potentiodynamic polarization, Auger electron spectroscopy, thermodynamic diagrams and the Mott-Schottky relation. The chemical compositions and electronic structures of the passive films were found to be strongly pH-dependent. In alkaline solutions, a secondary passivation was clearly observed on potentiodynamic polarization curves. The passive films were a mixture of Cr2O3 and FeCr2O4 below the flat band potential of nickel oxide and were NiFe2O4 above this potential. Electronic structure models, describing the electrochemical properties of the passive films, are proposed and discussed.

British Library Electronic Table of Contents (United Kingdom)

The gilthead seabream, Sparus aurata, represents an important economic resource for Mediterranean aquaculture. In spite of its wide geographic distribution and economic importance, only recently studies have been carried out on the genetic composition of natural populations, which have revealed a picture of a heterogeneous degree of genetic differentiation among S. aurata populations. In this study an allozyme analysis of samples from six different collecting sites along the Italian and Croatian coasts was carried out, covering an area in the Central Mediterranean sea that has yet to be investigated through gene-enzyme systems. Data on 26 gene loci, 10 of which are polymorphic, indicate a slight but significant genetic structure (FST = 0.0167) of the species. A hierarchical analysis of pop...

International Nuclear Information System (INIS)

Diurnal and seasonal thermal constancy, a greatly delayed seasonal temperature maximum, and summer cool and winter warm conditions characterize the stream environment below a deep-release dam in Colorado. Low diversity index and equitability values and changes in macroinvertebrate species composition may result from failure of the temperature regime to provide the thermal stimuli essential for various life-cycle phenomena. It is hypothesized that the following sublethal effects, directly or indirectly resulting from the modified temperature regime, may further alter macroinvertebrate community structure: reduction of niche overlap and a shift toward an equilibrium community as a consequence of reduced environmental fluctuation; more intense competition associated with greater productivity; elimination of major invertebrate predators; and failure of the limited temperature range to provide optimal temperatures for various physiological ...

British Library Electronic Table of Contents (United Kingdom)

In order to better understand the structure and composition of forest plant communities, we aimed to predict the abundance of understory herbaceous species locally at the stand level and according to different environments. For this, we seeked to model species distributions of abundance at a regional scale in relationship with the local stand structure (canopy openness) and regional soil resources (soil pH). Floristic inventories, performed in different light and soil conditions located in 1202 records of north eastern France, were used to analyze the combined effect of canopy openness and soil pH on the abundance of 12 common western European forest species: Anemone nemorosa, Deschampsia flexuosa, Festuca altissima, Hedera helix, Lamium galeobdolon, Lonicera periclymenum, Molinia caerulea...

International Nuclear Information System (INIS)

Experimental data on A-15 binary phases (the lattice parameter dependence on composition, phase diagrams, etc.) have been considered and the so-called ''compounds with A-15 structure'' are shown to be solid solutions of element substitution in the structure of A-15 type. Values of lattice parameter and atomic volume of A-15 modifications for 21 elements have been obtained (for Zr, W, Nb, Mo, V in particular). There has been shown the possibility of calculation of atomic volumes and lattice parameters of A-15 binary phases at the lack of direct experimental data. The essential role of atomic volume relations of different phases has been observed for the estimation of stability conditions of A-15 phase.

International Nuclear Information System (INIS)

... radiation effects RADIATIONS. WOOD-PLASTIC COMPOSITES.

International Science & Technology Center (ISTC)

New Composite Multifunctional Coatings Produced Using SHS-Electrodes

Energy Technology Data Exchange (ETDEWEB)

In this study, WO{sub 3} thin films were grown on glass substrates using an aqueous solution containing tungstate (NH{sub 4}){sub 2}WO{sub 4} as precursor. The substrate temperature incremented from 250 to 500 deg. C, by steps of 50 deg. C. The structural properties were investigated using XRD, atomic force microscopy and scanning electronic microscopy techniques. Microprobe analyses showed that a balanced stoichiometric composition was obtained for thin films prepared at T{sub s} = 350 and 400 deg. C. The X-ray diffraction analyses showed different structure crystallography in function of the substrate temperature. Moreover, films deposited at 400 deg. C were annealed in air for 2 h at 450 and 500 deg. C, respectively and the structural changes due to heat treatment were studied. Finally, the optical properties of these films were carried out using optical measurements of transmittance T({lambda}) and ...

Energy Technology Data Exchange (ETDEWEB)

The LiMnO{sub 2} lamellar oxide, obtained by exchange reaction from its sodium homologue {alpha}-NaMnO{sub 2}, has been used as a positive electrode for lithium batteries. After the first electrochemical cycle, the shape of the potential-composition curve changes and indicates a change in the structure. This modification changes imperceptibly at each cycle and after about 40 cycles, a stationary state is reached. Powder spectra refinement using the Rietvelt method shows a migration of manganese ions from the thin sheets towards the inter-sheet space. After a single cycle, 8% of the manganese ions are already present in the lithium site and this rate reaches 13% after 3 cycles. During long cycling, a redistribution of ions and vacancies inside the cfc oxygenated pile leads to a structure very similar to the LiMn{sub 2}O{sub 4} spinel. This structure evolution is to be compared with the one obtained from ...

International Nuclear Information System (INIS)

The information of phase transformation is attained by in situ XRD experiments leading to the knowledge of topological threshold in GeS2-Ga2S3 glasses. The turning point of phase transformation behavior is demonstrated to be glasses containing 14-15 mol% Ga2S3. To interpret it a network demixing model is further improved and proposed for the structure of these ternary or quasi-binary chalcogenide glasses. For the nearest-neighbor coordination environment of glass with a transitional composition of 85.7 mol% (6/7) GeS2.14.3 mol% (1/7) Ga2S3, six-coordinated [S3Ga-X-GaS3] units (X=S or None) are well isolated by the [GeS4] structures, which contributes to the decreasing of precipitation of Ga2S3 crystals in (100-x)GeS2-xGa2S3 (x?14.3) glasses corresponding to the experimental evidence of the phase transformation behavior. This scenario of intermediate-range structural order, firstly, includes the ...

International Nuclear Information System (INIS)

The Physikalisch-Technische Bundesanstalt (PTB), Germany's national metrology institute, developed an alignment strategy to specify elemental depth profiling in vertical sidewall layers on structured wafers. For this purpose, PTB's irradiation chamber for 200 mm and 300 mm silicon wafers was used to combine total-reflection X-ray fluorescence (TXRF) and grazing incidence XRF (GIXRF) techniques by employing monochromatized undulator radiation of the BESSY II electron storage ring. 3-D test structures were fabricated to develop an optimal alignment strategy allowing for depth profiling in such nanolayers. The test structures consisted of silicon bars with widths/spacings either in the ?m or in the nm range. In order to be able to differentiate the sidewalls more easily from the remainder of the structures, they were provided with an additional silicon nitride layer. Four structure ...

International Nuclear Information System (INIS)

Interest to thin film of metals' silicides first of all is conditioned intrinsic al them unique physical properties. On their basis of it is possible to produce extremely sophisticated devices of solid-state electronics, production which needs the controlled change of physics, chemical and electrical properties with high-level of accuracy. On the present time most are in detail investigated composition, structure and properties of three-dimensional samples of metals' silicides. In the last years the intensive are led to researches in the direction of creation and study of physical-chemical properties thin (500-1000 Angstroms) and ultrafine (100-120 Angstroms) films silicides. It has information about composition, morphology of surface and emission of properties of thin film of silicides of barium, of cobalt and of palladium, was obtained in conditions of ultra-high vacuum. Low energy ion implantation and further annealing ...

International Nuclear Information System (INIS)

K#beta#-to-K#alpha# x-ray intensity ratios of Fe and Ni in pure metals and in Fe_xNi_1_-_x alloys (x=0.20, 0.50, 0.58) exhibiting similar crystalline structure have been measured following excitation by 59.54 keV #gamma# rays from a 200 mCi "2"4"1Am point source to understand why the properties of the Fe_xNi_1_-_x (x=0.2) alloy are distinct from other alloy compositions. The valence electronic structure of Fe and Ni in the samples has been evaluated by comparing the measured K#beta#-to-K#alpha# intensity ratios with the results of multiconfiguration Dirac-Fock calculations. Significant changes in the 3d electron population (with respect to the pure metal) are observed for Fe and Ni for certain alloy compositions. These changes can be explained by assuming rearrangement of electrons between 3d and (4s,4p) band states of the individual metal atoms. It has been found that the valence electronic ...

International Nuclear Information System (INIS)

Normal fetal brain maturation can be studied by in vivo magnetic resonance imaging (MRI) from the 18th gestational week (GW) to term, and relies primarily on T2-weighted and diffusion-weighted (DW) sequences. These maturational changes must be interpreted with a knowledge of the histological background and the temporal course of the respective developmental steps. In addition, MR presentation of developing and transient structures must be considered. Signal changes associated with maturational processes can mainly be ascribed to the following changes in tissue composition and organization, which occur at the histological level: (1) a decrease in water content and increasing cell-density can be recognized as a shortening of T1- and T2-relaxation times, leading to increased T1-weighted and decreased T2-weighted intensity, respectively; (2) the arrangement of microanatomical structures to create a symmetrical or asymmetrical ...

Energy Technology Data Exchange (ETDEWEB)

There is presently considerable interest in wear resistant coatings produced using closed field unbalanced magnetron sputtering technology. For example, layered films of diamond-like carbon (DLC) with tungsten or titanium additions have been widely reported. The benefit is that the mechanical properties are enhanced (e.g. giving greater toughness); also it is possible to control the stress state and enhance adhesion. Here we report the further development of this concept by the addition of TiN, TiCN and TiC layers in DLC-based composites, utilizing an additional source of electrons in the vicinity of substrate to enhance ionisation of the plasma and increase coating density. Composite coatings of ceramics TiN, TiC{sub x}N{sub y}, TiC, CrN, TiCrN, TiCrCN, TiCrC, metal doped Ti{sub x%}-DLC and their combinations were deposited on 316 stainless steel substrates. The mass flow of reactive gases into the chamber was controlled using plasma optical ...

International Nuclear Information System (INIS)

Microdamage naturally occurs in bone tissue as a result of cyclic loading placed on the body from normal daily activities. While it is usually repaired through the bone turnover process, accumulation of microdamage may result in reduced bone quality and increased fracture risk. It is unclear whether certain areas of bone are more susceptible to microdamage than others due to compositional differences. This study examines whether areas of microdamaged bone are chemically different than undamaged areas of bone. Bone samples (L3 vertebrae) were harvested from 15 dogs. Samples were stained with basic fuchsin, embedded in poly-methylmethacrylate, and cut into 5-(micro)m-thick sections. Fuchsin staining was used to identify regions of microdamage, and synchrotron infrared microspectroscopic imaging was used to determine the local bone composition. Results showed that microdamaged areas of bone were chemically different than the surrounding undamaged ...

International Nuclear Information System (INIS)

The thermodynamics of the Sr-Si system is of fundamental importance for the understanding of eutectic modification of Al-Si alloys. At the same time, strontium silicides have recently been found to have potential applications in electronic devices. Renewed research efforts have led to a re-evaluation of the phase equilibria in this system, resulting in the discovery of previously undetected stable intermetallic compounds. In this work, we investigate the finite temperature thermodynamic properties of the stable (and metastable) Sr-Si intermetallics. The vibrational properties of the intermetallic compounds are calculated within harmonic theory, with quasi-harmonic corrections to account for the effects of thermal expansion. The total free energies of the compounds are computed considering vibrational and electronic contributions, as well as weak anharmonic corrections. The ground state of the system is predicted and compared to previous experimental and computational results. The ...

Energy Technology Data Exchange (ETDEWEB)

The structural change of the (100-x)(0.6Li[sub 2]S[center dot]0.4SiS[sub 2])centre dotxLi[sub 3]PO[sub 4] oxysulfide glassesduring crystallization was analyzed by means of solid-state nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS). The unique tetrahedral units of SiO[sub n]S[sub 4-n] (n=1,2,3) and PO[sub n]S[sub 4-n] (n=1,2,3) present in the glass samples vanished and the SiS[sub 4], PS[sub 4], SiO[sub 4] units increased with proceeding of the crystallization process. Nonbridging sulfur and oxygen atoms decreased while bridging oxygens and S[sup 2-] increased with proceeding of the crystallization process. Large structural difference between the glass and the corresponding crystallized sample explained the high stability against crystallization found in the oxysulfide glass with the composition of X=5. (author)

Energy Technology Data Exchange (ETDEWEB)

In the production of heavy-sectioned ferritic spheroidal graphite iron castings for such parts as spent fuel shipping container (cask), undesirable structures like abnormal graphite lamella, pearlite or so-called chinese script type of inclusions tend to appear, deteriorating the mechanical properties at the central part of the section where molten iron freezes last. 500 mm thick cylindrical vessels with bottom, weighing 18 tons and 33 tons, were poured as trial products of casks. Solidification structure and mechanical properties were examined at many portions of the castings. By controlling chemical composition, solidification time and inoculation process the structure and the mechanical properties in the last portion of the section to solidify were improved. Sufficiently homogeneous heavy-sectioned ferritic spheroidal graphite iron castings were successfully produced in the as-cast state. In ...

International Nuclear Information System (INIS)

Excitonic transitions in metalorganic vapor phase epitaxially grown In_xGa_1_-_xP/In_0_._4_8(Al_0_._7Ga_0_._3)_0_._5_2P strained single quantum-well structures are characterized using low-temperature photoluminescence and photoluminescence excitation (PLE) spectroscopies. The structures consist of several uncoupled quantum wells with thicknesses between 1.2 and 11.3 nm, and compositions x of 0.48 (nominally lattice matched) and 0.56 (#approx#0.6% biaxial compressive strain). The photoluminescence spectra exhibit intense peaks over the wavelength range 550--650 nm, with linewidths between 7 and 23 meV depending on the well thickness. The PLE spectra reveal strong heavy-hole and light-hole transitions, as well as higher-order (n=2) transitions in the thicker wells. The heavy-hole/light-hole splitting shows little dependence on well thickness in the strained structures, indicating a relatively large ...

Energy Technology Data Exchange (ETDEWEB)

The properties of polycrystalline (Ti, Al)N coatings deposited on non-nitrided, classically plasma-nitrided and low pressure plasma-nitrided AISI H11 steel samples were investigated. The plasma deposition and low pressure plasma nitriding were performed in a Z700-LH magnetron sputter ion plating unit, while a separate unit was used for plasma nitriding of specimens at a pressure of several millibars. The (Ti, Al)N coating was deposited onto all the samples using the same equipment as for the plasma deposition and low pressure plasma nitriding. For the characterization of the composite structures, the following methods were used: scratch test, X-ray diffraction analysis, scanning electron microscopy, scanning tunnelling microscopy and microhardness testing. It was found that plasma nitriding prior to coating deposition strongly affects the growth and properties of hard coatings, such as the microhardness, adhesion, preferred orientation, ...

International Nuclear Information System (INIS)

The synthesis, crystal structure, thermal stability and absorbance spectra of perovskite-type oxynitrides with the general formula SrTi1-xNbx(O,N)3 (x=0.05, 0.10, 0.20, 0.50, 0.80, 0.90, 0.95) have been investigated. Oxide samples were prepared by a polymerized complex synthesis route and post-treated under ammonia at 850 oC for 24 h to substitute nitrogen for oxygen. Synchrotron X-ray powder diffraction (XRD) evidenced that the mixed oxide phases were all transformed into oxynitrides with perovskite-type structure during a thermal ammonolysis. SrTi1-xNbx(O,N)3 with compositions x?0.80 crystallized in a cubic and samples with x?0.90 in a tetragonal structure. The Rietveld refinement indicated a continuous enlargement of the lattice parameters towards higher niobium content of the samples. Thermogravimetric analysis (TGA) and hotgas extraction revealed the dependence of the nitrogen incorporation upon ...

International Nuclear Information System (INIS)

The software package VIBA-lab1, which incorporates PIXE and RBS energy spectra simulation has now been extended to include the simulation of elemental maps from 3D structures. VIBA-lab1 allows the user to define a wide variety of experimental parameters, e.g. energy and species of incident ions, excitation and detection geometry, etc. When the relevant experimental parameters as well as target composition are defined, the program can then simulate the corresponding PIXE and RBS spectra. VIBA-LAB2 has been written with applications in nuclear microscopy in mind. A set of drag-and-drop tools has been incorporated to allow the user to define a three-dimensional sample object of mixed elemental composition. PIXE energy spectra simulations are then carried out on pixel-by-pixel basis and the corresponding intensity distributions or elemental maps can be computed. Several simulated intensity distributions for some 3D objects are ...

International Nuclear Information System (INIS)

The distribution of Cu, Ni, Co and Mn between an aqueous solution of constant ionic strength and Versatic Acid 911 diluted with benzene was investigated. Only one extracted species of Cu was revealed to have a dimeric structure of the composition (CuR_2.RH)_2, while both monomer and dimer were found in the extraction of Ni, Co and Mn. The curve-fitting method was employed to determine these species, from which the composition of the extracted species was found to be NiR_2.4RH and (NiR_2.2RH)_2, CoR_2.4RH and (CoR_2.2RH)_2, and MnR_2.4RH and (MnR_2.2RH)_2, respectively. The apparent equilibrium constants of the above species and those between monomer and dimer were also determined. The curve-fitting method was proved to be a precise method for determining the equilibrium constants and extracted species. (author).

Energy Technology Data Exchange (ETDEWEB)

Research and development underway since 1982 has led to the development of a method of reinforcing wood and wood composite structural products (WWC) using high-strength fiber-reinforced plastic. This method allows the use of less wood fiber and lower grade wood fiber for a given load capacity. The first WWC in which reinforcement has been marketed is glulam beams. Marketed under the trade name FiRP{trademark} Reinforced glulam, the product has gained code approval and is now being used in the construction of buildings and bridges in the United States, Japan and other countries. The high-strength fiber-reinforced plastic (FiRP{trademark} Reinforced panel (RP)) has specific characteristics that are required to provide for proper use in WWC`s. This paper discusses these characteristics and the testing requirements to develop code approved allowable design values for carbon, aramid and fiberglass RP`s for such uses. Specific issues such as ...

British Library Electronic Table of Contents (United Kingdom)

Objectives To clarify the relationship between bone mineral density (BMD) and body composition in Japanese women aged 18?40?years with low forearm BMD. Methods The subjects were Japanese199 women who had been selected for inclusion in the study based on a low forearm BMD determined at the Annual Women?s Health Examination. The subjects? mean (? standard deviation) age, body height, body weight, and body mass index (BMI) were 33.5 (?4.3) years, 158.1 (?5.1) cm, 49.6 (?5.7) kg, and 19.8 (?2.1), respectively. The BMD of the lumbar spine, total body, and left arm were measured using dual-energy X-ray absorptiometry (DXA). Fat mass (FM), bone-free lean tissue mass (LTM), and body fat percentage (BF%) were measured simultaneously with DXA. Results In the structural equation model, the standardiz...

Energy Technology Data Exchange (ETDEWEB)

A range of additives has been developed for enhancing grafting yields in a variety of systems initiated by ionizing radiation. Cellulose has been adopted as the predominant naturally occurring model backbone polymer in these studies because of its structural relationship to wood which is the reference substrate for the work reported in the related second part of this paper concerning composites. Some experiments have been performed with the other major naturally occurring polymer, wool. For comparison purposes with synthetic materials, some studies have also been performed with polypropylene as trunk polymer. Styrene has been used as a predominant monomer in grafting with some experiments utilizing the acrulates like methyl methacrylate. The role of solvent in grafting has been evaluated. UV has been used as initiator to replace ionizing radiation for certain experiments. The additives used were mineral acids, lithium salts, multifunctional ...

Science.gov (United States)

Wood Plastic Composites (WPCs) have experienced a healthy growth during the last decade. However, improvement in properties is necessary to increase their utility for structural applications. The toughness of WPCs can be improved by creating a fine cellular structure while reducing the density. Extrusion processing is one of the most economical methods for profile formation. For our study, rectangular profiles were extruded using a twin-screw extrusion system with different grades of HDPE and with varying wood fibre and lubricant contents together with maleated polyethylene (MAPE) coupling agent to investigate their effects on WPC processing and mechanical properties. Work has been done to redesign the extrusion system setup to achieve smoother and stronger profiles. A guiding shaper, submerged in the water, has been designed to guide the material directly through water immediately after exiting the die; instead of passing ...

International Nuclear Information System (INIS)

Short note.

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Science.gov (United States)

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KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

This paper reports on a series of laboratory and controlled test site measurements of the thermal conductivity of polyisocyanurate foam laminated boardstock roof insulations produced with several different blowing agents; CFC-11, HCFC-123, HCFC-14lb, and two blends of the HCFCs. The behavior of the experimental foams with HCFCs is compared to that of conventional polyisocyanurate foam blown with CFC-11. Thermal drift observed from two years of field exposure is compared to laboratory accelerated aging tests and the laboratory and field measurement techniques are described. This work is part of a Joint Industry/Government Project established in the United States to evaluate the technical viability of HCFC alternative blowing agents for polyisocyanurate foam roof insulations.

International Nuclear Information System (INIS)

We discuss geochemical and sedimentological characteristics of 12 tephra layers, intercalated within the finely laminated sediments of Lake Van. Within the about 15 kyr long sediment record studied, volcanic activity concentrated in the periods 2.6-7.2 and 11.9-12.9 kyr B.P. Concentrations of 25 elements provide the geochemical fingerprint of each tephra layer and allow comparison to literature values of potential source volcanoes such as Mts. Nemrut and Suephan. The youngest two tephra layers (and probably also the other three ashes from the 2.6-7.2 kyr B.P. eruptions) originate from the Nemrut volcano. The source of the older tephra (11.9-12.9 kyr B.P.), however, remains unidentified.

Science.gov (United States)

... Accession Number : ADD345858. Title : Nondestructive Testing of Polymeric Composite Sandwich Panels Via the Thermographic Halo,. ...

Energy Technology Data Exchange (ETDEWEB)

A fuel composition comprising a liquid hydrocarbon fuel and a detergent amount of the product of reaction between a polyamine and a stearic acid is described.

Science.gov (United States)

... The ultimate compressive strength (UCS) for the HMU/BSG composite is essentially equivalent to the tensile strength exhibited by this system. ...

Science.gov (United States)

... Accession Number : ADD808679. Title : Advanced Composites for Aerospace Require Waterjet Technology. Descriptive Note : Journal article. ...

International Nuclear Information System (INIS)

Molar excess volumes, VE and molar excess enthalpies, HE of 1,3-dioxolane (D) (i) + propan-1-ol, 1,3-dioxolane (i) + butan-1-ol and 1,3-dioxolane (i) + butan-2-ol (j) binary mixtures have been measured as a function of composition at 308.15 K. The analysis of VE data by graph, theoretical approach reveals that while propan-1-ol, butan-1-ol exist as associated entities in the pure state; 1,3-dioxolane and butanol exist as monomers in their pure state. These (i+j) binary mixtures are characterized by interactions between ethereal oxygen atom of D(i) and hydrogen atom of alkanols. The IR studies lend additional support to the proposed structure of molecular entitles in these mixtures. The energetics of the mixtures have also been studied.

British Library Electronic Table of Contents (United Kingdom)

The characteristics of aerosol generation were studied experimentally in an ammonia-based wet flue gas desulfurization process. Particle size distributions and concentrations, morphologies and compositions before and after desulfurization were measured using an electrical low pressure impactor and scanning electron microscopy, respectively. The results show that aerosols can be generated between ammonia and sulfur dioxide resulting in gas-phase reaction and the aerosol concentration at the outlet of scrubber is significantly higher than at the inlet. Before desulfurization the particles are primarily silica-alumina minerals including O, Al, Si and C, while after ammonia-based desulfurization aerosol particles have smooth surfaces with regular structures, such as cubic and prismatic crystal...

CERN Document Server

The development of a replacement to the conventional film based X-ray imaging technique is required for many reasons. One possible route for this is the use of a large area film of a suitable semiconductor overlaid on an amorphous silicon readout array. A suitable semiconductor exists in cadmium telluride and its tertiary alloy cadmium zinc telluride. In this thesis the spectroscopic characteristics of commercially available CZT X- and gamma-radiation detectors are established. The electronic, optical, electro-optic, structural and compositional properties of these detectors are then investigated. The attained data is used to infer a greater understanding for the carrier transport in a CZT radiation detector following the interaction of a high energy photon. Following this a method used to fabricate large area films of CdTe on a commercial scale is described. This is cathodic electrodeposition from an aqueous electrolyte. The theory and ...

Energy Technology Data Exchange (ETDEWEB)

This paper attempts to explain the peculiarities of the radial-distribution function of metal glasses without involving ideas of the amorphous structure. On a computer, the radial atomic density for a spherical eutectic single crystal of the composition Fe/sub 84/C/sub 16/ of radius 15 A formed by alternating small crystals of e-Fe and Fe/sub 3/C of cubic form with the edge of the cube ca 10 A. For the sake of clarity, the diagram of such a quasisingle crystal is shown and has been given a cubic boundary. The change in the relationship between the heights of the subpeaks of the second maximum of the radial distribution function of atoms in the Fe-B glasses with a change in the concentration of boron can be explained by the change in the space group of the Fe/sub 3/B metastable boride which is formed in this system.

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The studied coal bearing series has a parallel origin. The following facial complexes are isolated in its composition: lakes free of vegetation without coal interlayers; overgrown lakes of their margins which are poor in coals; swampy lakes, whose peat beds formed coal layers of shallow or moderate depth; channel sediments without coal layers and swamps from between channel spaces which created thick coal strata of high quality for which, however, a strong changeability in thickness is intrinsic. The coal strata are normally split towards the central parts of the lake basins and river channels. The coal presence of the suite is reduced along the section which is associated with the replacement of the lake swamp conditions of sedimentation by lake river conditions. A paleotectonic analysis established that the distribution of the zones richest in coal was controlled by consedimentational structural elements.

International Nuclear Information System (INIS)

Here we reported a two-step procedure for preparing a novel polymeric based solid-solid phase change heat storage material. Firstly, a copolymer monomer containing a polyethylene glycol monomethyl ether (MPEG) phase change unit and a vinyl unit was synthesized via the modification of hydrogen group of MPEG. Secondly, by copolymerization of the copolymer monomer and phenyl ethylene, a novel polymeric based solid-solid phase change heat storage material was prepared. The composition, structure and properties of the novel polymeric based solid-solid phase change material were characterized by IR, "1H NMR, DSC, WAXD, and POM, respectively. The results show that the novel polymeric based solid-solid phase change material possesses of excellent crystal properties and high phase change enthalpy.

Energy Technology Data Exchange (ETDEWEB)

Microalloyed or high strength low alloy (HSLA) steels are carbon-manganese steels containing small amounts of Nb, V or Ti. The excellent mechanical properties of these alloys, particularly high yield strength, usually obviate the need for expensive quench and tempering operations. Furthermore, the presence of a significant amount of nitride-forming elements in some microalloyed steels has generated interest in the applicability of these alloys as a new generation of nitriding steels. In this paper, a study of the plasma nitriding behaviour of a commercially available microalloyed steel MAXIMA{sup TM} is reported. A comparison is made with a traditional quenched and tempered nitriding steel (En19), plasma nitrided under similar conditions. Optical and scanning electron microscopy in conjunction with microhardness measurements and X-ray diffraction were utilized to characterize the nitrided surfaces. The observed differences in the thickness and structure of the ...

British Library Electronic Table of Contents (United Kingdom)

Inspired by the recent realizations of quantum dot (QD)-DNA conjugation, we study the spectral density of a magnetic impurity coupled to a mesoscopic semiconducting host. Using a combination of exact diagonalization technique and an analytic approach, we demonstrate that various types of resonances occur according to the relative position of impurity levels (IL) with respect to the host levels (HL). While the usual Coulomb peaks appear when the IL lie inside a band gap, with IL approaching HL and hybridization activated, they shift nonlinearly with the repulsion strength and even undergo splitting for a strong hybridization. When IL merge into HL, multiple resonances of a comblike structure are found along with a parity effect.

Energy Technology Data Exchange (ETDEWEB)

The microstructure evolution of nine samples from three Ir-base ternary systems, Ir-Nb-Hf, Ir-Nb-Ta, and Ir-Nb-Ti, was investigated by microstructure observation using scanning electron microscopy (SEM), composition map-analysis using electron probe microscopy analysis (EPMA), and phase determination using X-ray diffraction (XRD) patterns. The fcc/L1{sub 2} two-phase structure was detected in all the samples. Lattice misfits between fcc and L1{sub 2} phases were calculated. Ir-Nb-Ta and Ir-Nb-Ti alloys exhibited a microstructure quite similar to that of Ni-base superalloys, and the cuboidal L1{sub 2} precipitates in Ir-Nb-Ta and Ir-Nb-Ti alloys could maintain up to 1900 {sup o}C.

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The magnetic susceptibility and electrical resistivity in cerium and neodymium titanate bronzes in Ln/sub 2/3+x/TiO/sub 3+y/ of the perovskite structure were investigated in the temperature range 77-450/sup 0/K. The deviation of the 1/x = f(T) dependence from the Curie-Weiss law, found for a majority of the compositions, was interpreted from the crystal-field effect based on the state of the Ce/sup 3 +/ and Nd/sup 3 +/ cations. For a number of the phases, a transition from metallic conductivity at high temperatures to semiconducting conductivity was detected at temperatures below 200-250/sup 0/K, which agrees well with the conclusion about the temperature dependence of x, related to the subsystem of Ti/sup 3 +/ cations.

Energy Technology Data Exchange (ETDEWEB)

Dynamic stability enhancement of composite mode oscillations of interconnected power systems by means of a hybrid power system stabilizer is discussed here. The proposed Hybrid PSS is of a two-level structure composed of a local PSS for local mode and a global PSS for inter-area mode damping. Here, the input of the global stabilizer is the center of inertia speed deviation of slow-coherent generators. The paper is focused on the practical considerations in implementation of the proposed stabilizer. First, the optimum allocation of this stabilizer is discussed. The authors introduce an index of mode-input-assignability, by which the best sites of the stabilizer can be identified. Next, for practical applications, an estimation method for the approximation of the input of the global PSS is introduced. An approximated value of the center of inertia speed is obtained from a suitable combination of the rotor speed data of a few properly selected key ...