Science.gov (United States)

> Develoopments which have imporved fuel core quality and reduced production costs are described. These developments in the melting and casting of uranium ingots arei modification of the crucible and knockout-slide assembly, substitution of uncoated crucibles for coated crucibles, and substitution of a one-piece gun barrel mold for a vertically split mold. (N.W.R.)

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.

Energy Technology Data Exchange (ETDEWEB)

This report summarizes some experiences gathered when using the semi-empirical temperature model that forms the heart of the steel casting advisory system `TUNDTEMP` in simulating the casting process. The model estimates the evolution of the liquid steel temperature in a tundish of a continuous casting machine through a temperature prediction at a couple of central time instants during the casting process. The results are compared with corresponding actual observations during the castings - measured steel temperatures and recorded casting difficulties and interruptions. Explanations for the possible discrepancies are suggested. Starting from a heuristically chosen set of model parameter values, some developing steps have been tested to reduce the simulation errors. The study concentrates mainly on temperature predictions for single heat ...

Energy Technology Data Exchange (ETDEWEB)

The possibility of rapid heat treatment (RHT) application to titanium castings has been studied. It was shown that such treatment provides a significant improvement of intragrain structure and mechanical properties of cast ({alpha}+{beta})-titanium alloys. ((orig.))

Energy Technology Data Exchange (ETDEWEB)

A new interest in magnesium alloys has arisen since light-weight constructions have become more and more attractive. Products that are currently available are mostly cast, forged, and extruded. A cost-effective production of sheet metals will render new perspectives in the design of light-weight constructions. The development of new casting technologies like thin slab casting or strip casting with an in-line rolling process is expected to result in a shorter processing time featuring a high potential of saving energy, time, and cost. Particular attention is paid to the casting process parameters such as casting speed and solidification speed. This article deals with some aspects of a magnesium-adapted single-belt caster. Results of casting experiments and material examination are shown as well as some advices given concerning safety and ...

Energy Technology Data Exchange (ETDEWEB)

Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US compentiveness in the casting arena. Lawrence Livermore National Laboratory (LLNL) is the home of a wide range of R&D projects that push the boundaries of state-of-the art casting. LLNL casting expertise and technology include: casting modeling research and development, including numerical simulation of fluid flow, heat transfer, reaction/solidification kinetics, and part distortion with residual stresses; special facilities to cast toxic material; extensive experience ...

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

Plastic formability of cast magnesium alloy that were hot rolled after roll strip casting was investigated to ascertain the feasibility of semi-solid strip casting process of AZ31B magnesium alloy. Hot rolling and heat treatment conditions were changed to examine which conditions were appropriate for producing AZ31B wrought magnesium alloys after strip casting process. Microscopic observation of the crystals of the manufactured wrought magnesium alloys was performed. It has been found that a limiting drawing ratio of 2.7 was possible in a warm deep drawing test of the cast magnesium alloy sheets after being hot rolled. (orig.)

Energy Technology Data Exchange (ETDEWEB)

AZ31 and experimental ZMA611 alloys were strip cast into 2 mm thick strips. The as-cast AZ31 alloy strip consists of columnar dendrites. On the other hand, as-cast ZMA611 alloy strip shows equiaxed dendritic structure through the thickness of strip. These alloys were subjected to various thermomechanical treatments and their tensile properties were evaluated. Strip cast AZ31 alloy in H24 condition has equivalent yield and tensile strengths with similar ductility compared to commercial ingot cast AZ31-H24 alloy, indicating that strip casting is a viable process for the fabrication of Mg alloy strips. The ZMA611 alloy has a large volume fraction of fine dispersoid particles in the microstructure, resulting from the beneficial effect of strip casting on microstructural refinement. It has been shown that the ZMA611 alloy has superior tensile ...

Energy Technology Data Exchange (ETDEWEB)

This is the final report covering work performed on research into methods of attaining clean ferrous castings. In this program methods were developed to minimize the formation of inclusions in steel castings by using a variety of techniques which decreased the tendency for inclusions to form during melting, casting and solidification. In a second project, a reaction chamber was built to remove inclusions from molten steel using electromagnetic force. Finally, a thorough investigation of the causes of sand penetration defects in iron castings was completed, and a program developed which predicts the probability of penetration formation and indicates methods for avoiding it.

Energy Technology Data Exchange (ETDEWEB)

Effects of rolling conditions on warm deep drawability of cast magnesium alloy that were hot rolled after roll strip casting were investigated to ascertain the feasibility of twin-roll strip casting process of AZ31B magnesium alloy. Hot rolling and heat treatment conditions were changed to examine which conditions were appropriate for producing AZ31B wrought magnesium alloys after strip casting process. Microscopic observation of the crystals of the manufactured wrought magnesium alloys was performed. It has been found that a limiting drawing ratio of 2.7 was possible in a warm deep drawing test of the cast magnesium alloy sheets after being hot rolled. (orig.)

Science.gov (United States)

A reactor was proposed in which the breeder mantel would consist of a charge of homogeneous cast breeder elements, so that the breeder element has the same shape as the fuel elements. By this method it would be possible to use the breeder element after its irradiation immediately for the charging of the fuel elements.

Energy Technology Data Exchange (ETDEWEB)

A brief description is given of some commercially-available wear-resistant products suitable for use in mine environments. The materials are cast basalt, cast or sintered alumina, and a heat-treated martensitic iron, and they can be used as linings for pipes, bunkers and chutes.

Science.gov (United States)

... The ultimate compressive strength was measured, and values for Young's modulus were calculated from the linear portion of the test curve. ...

Energy Technology Data Exchange (ETDEWEB)

Lining of fused cast basalt tiles is recommended for various pieces of equipment constituting a coal preparation plant.

Energy Technology Data Exchange (ETDEWEB)

Hamiltonian light-front dynamics of quantum fields may provide a useful approach to systematic nonperturbative approximations to quantum field theories. The authors investigate inequivalent Hilbert-space representations of the light-front field algebra in which the stability group of the light front is implemented by unitary transformations. The Hilbert space representation of states is generated by the operator algebra from the vacuum state. There is a large class of vacuum states besides the Fock vacuum which meets all the invariance requirements. The light-front Hamiltonian must annihilate the vacuum and have a positive spectrum. Relations are exhibited of the Hamiltonian to the nontrivial vacuum structure. 30 refs.

International Nuclear Information System (INIS)

It is shown that vacuum instabilities possibly arising because of tachyons do not contradict any experimental evidence, and therefore that no objection against tachyon existence can be found even on this ground. (Auth.).

Energy Technology Data Exchange (ETDEWEB)

To make the surface composites with hard ceramics particles is an effective means for satisfying the request for the wear-resistance of the casting products. Covering casting is a general method for forming the composites by adding the adhesive into ceramics particles. However, due to the using of adhesive, pore and intermediate are easy to generate, and it is one of the reasons making the wear-resistance unstable. In the present study, it is attempted to form the wear-resistant composite layer by dispersing cast tungsten carbide (CTC) particles on the surface of wear-resistant 7 mass% Mn steel without using adhesives. Subsequently, the experiments on the wear-resistance of the obtained surface composites under several wear conditions are carried out. It is revealed by the results thereof that 7 mass% Mn steel surface composites with CTC particles have the wear-resistance which is even more excellent than those of white ...

KoreaScience (Korea)

Full Text Available

International Nuclear Information System (INIS)

Purpose: To enable the use of a vacuum container under a relatively high temperature or a high level radioactive dose. Constitution: Vacuum sealing materials for use in a vacuum container are made of resins such as polyimide and polyamide. The sealing materials are joined to the both surfaces of a plate-like insulator by means of adhesives or sealants, or the sealing materials are joined between two plate-like insulators by means of adhesives or sealants. They are situated within grooves of both of flanges, which are clamped tightly by insulation bolt and nut. Since the vacuum sealing materials are joined to the insulator by means of the adhesives or sealants, the reliability of the vacuum sealing can be improved without impairing the electrical insulation. The resin of the vacuum sealing material can be used for the radiation dose up to 10"8 rad, temperature up ...

Energy Technology Data Exchange (ETDEWEB)

This report summarizes the major features of the advisory tool `TUNDTEMP`, developed to act as a decision support in the continuous steel casting process. `TUNDTEMP` provides a means to predict abnormal phenomena of temperature origin in the casting that may be difficult to foresee in practical situations. The heart of the system is a semi-empirical calculation model that yields an estimate of the evolution of the tundish temperature of the liquid steel on the basis of a few important casting factors. The user interface of the system is to a large extent based on the visual presentation of the simulated results. The system also contains an optional rule based mechanism that provides assistance in the result interpretation and, if wished, linguistically formulates action recommendations. A separate program has been built for the tuning of the calculation model and for maintenance of the system. At the end of the report, the ...

British Library Electronic Table of Contents (United Kingdom)

Statement of problem Because noble dental casting alloys for metal ceramic restorations have a wide range of mechanical properties, knowledge of these properties is needed for rational alloy selection in different clinical situations where cast metal restorations are indicated. Purpose The purpose of this study was to compare the mechanical properties and examine both the fracture and polished surfaces of 6 noble casting alloys that span many currently marketed systems. Five alloys were designed for metal ceramic restorations, and a sixth Type GPT has Type IV alloy for fixed prosthodontics (Maxigold KF) was included for comparison. Material and methods Specimens (n=6) meeting dimensional requirements for ISO Standards 9693 and 8891 were loaded to failure in tension using a universal testin...

British Library Electronic Table of Contents (United Kingdom)

Statement of problem Titanium is the most biocompatible metal used for dental casting; however, there is concern about its marginal accuracy after porcelain application since this aspect has direct influence on marginal fit. Purpose The purpose of this study was to determine the effect that metal selection and the porcelain firing procedure have on the marginal accuracy of metal ceramic prostheses. Material and methods Cast CP Ti, milled CP Ti, cast Ti-6Al-7Nb, and cast Ni-Cr copings (n=5) were fired with compatible porcelains (Triceram for titanium-based metals and VITA VMK 95 for Ni-Cr alloy). The Ni-Cr alloy fired with its porcelain served as the control. Photographs of metal copings placed on a master die were made. Marginal discrepancy was determined on the photographs using an image ...

Energy Technology Data Exchange (ETDEWEB)

Georg Fischer GmbH operates a melting plant with several cupola furnaces in Mettmann. The plant supplies two casting plants for production of castings from nodular cast iron or malleable cast iron. It is now planned to convert one of the existing hot-blast cupola furnaces to the latest state of the art. Under special consideration are clear reduction of dust emission by use of a filtering separator below the permissible mass concentration according to the Clean Air Regulations; reduction of the current level of dumped waste by application of a new dust (residue) utilisation method; improvement of the total thermal efficiency of the cupola furnace melting plant by extensive, advanced utilisation of waste heat; and use of low-cost dust-like alternative fuels. (author).

Energy Technology Data Exchange (ETDEWEB)

This study presents the results of an 18-year long investigation of pipe deterioration in cyclone slag slurry transport. The goal was to study pipe behaviour in this extremely abrasive service and select an optimum piping material. Comparisons are given for high quality alloy cast steel pipes and pipes alined with cast basalt rings marketed under the name Abresist.

Energy Technology Data Exchange (ETDEWEB)

This report describes measurements performed with annular uranium metal castings of different enrichments to investigate the use of {sup 252}Cf-source-driven noise analysis measurements as a means to quantify the amount of special nuclear material (SNM) in the casting. This work in FY 97 was sponsored by the Oak Ridge Y-12 Plant and the DOE Office of Technology Development Programs. Previous measurements and calculational studies have shown that many of the signatures obtained from the source-driven measurement are very sensitive to fissile mass. Measurements were performed to assess the applicability of this method to standard annular uranium metal castings at the Oak Ridge Y-12 plant under verification by the International Atomic Energy Agency (IAEA) using the Nuclear Weapons Identification System (NWIS) processor. Before the measurements with different enrichments, a limited study of ...

Energy Technology Data Exchange (ETDEWEB)

A great deal of energy is necessary to manufacture castings, the greater part of which is wasted. Some general instructions are given on how to keep this part as low as possible. This is discussed particularly using the example of a heat recovery plant for foundries, especially in the melting and cooling of castings with the use of cupola furnace stack gas to produce hot gas. Further variants for recovering heat from the individual stages of a foundry process are listed. There are data on using this heat in operation.

Energy Technology Data Exchange (ETDEWEB)

The application of airborne sensors for providing environmental assessment and monitoring of a test site in an open cast mining area that is part of a lignite deposit in central Germany is described. Hyperspectral remote sensing data from three different sensors were tested. The hyperspectral scanner data was suitable for classification of different sediments and vegetation types and the water chemistry of residual mining lakes. Summary form only. 1 tab.

Science.gov (United States)

... Accession Number : ADD141533. Title : Yttrium Oxides in Vacuum-Plasma- Sprayed CoNiCrAlY Coatings,. Descriptive Note : Journal Article,. ...

Energy Technology Data Exchange (ETDEWEB)

A procedure and correlations are presented for predicting Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and J{sub IC} of aged cast stainless steels from known material information. The ``saturation`` impact strength and fracture toughness of a specific cast stainless steel, i.e., the minimum value that would be achieved for the material after long-term service, is estimated from the chemical composition of the steel. Mechanical properties as a function of time and temperature of reactor service are estimated from impact energy and flow stress of the unaged material and the kinetics of embrittlement, which are also determined from chemical composition. The J{sub IC} values are determined from the estimated J-R curve and flow stress. Examples of estimating mechanical properties of cast stainless steel components during reactor service are presented. A common ``lower-bound`` J-R curve for ...

Science.gov (United States)

... more than expected in developing a unique bond strength measurement protocol that is important for a wide range of bond strength measurements. ...

Science.gov (United States)

... The nature of the vacuum breakdown mechanism presents just such a problem and the relative significance or total absence of several processes ...

International Nuclear Information System (INIS)

... bismuth chlorides bismuth 207 cadmium chlorides efficiency evaporation high

International Nuclear Information System (INIS)

Development of a front end system for a high energy proton accelerator is in progress at Korea Atomic Energy Research Institute (KAERI) for basic science and industrial applications. The proper vacuum components has been installed and operated successfully between ion source and RFQ. The reliable operation of the accelerator has been completed at vacuum system in the high and ultra high vacuum range under operating conditions. Proper control system for the vacuum instruments, based on PC operated by Windows, has been designed and constructed by control group at PAL. As PC operated by windows with inherent instability does not proper, embedded system can be replaced for reliable operation system, such as VME system operated by vxWorks.

Energy Technology Data Exchange (ETDEWEB)

The use and application of remote sensing data for monitoring the environmental impacts of open cast lignite mining in Eastern Germany is described. This investigation is based on the digital analysis of several Landsat-TM and ERS-1 data sets acquired from 1989 to 1994. The characteristics of the imagery enable quantitative analysis of different open cast mine features, such as waste, water bodies, change of land use, reclamation processes and estimation of vegetation cover in the affected areas. On the basis of the Maximum Likelihood Classification of Landsat Thematic Mapper (TM) data the open cast mining areas were separated into bare open cast areas and areas of less and dense vegetation. The bare open cast areas were classified with respect to type of different sediments and the vegetation was seperated into different classes according to the age of the vegetation and the ...

Energy Technology Data Exchange (ETDEWEB)

A new methodology for three-dimensional (3-D) numerical modeling of the continuous steel casting process is presented and evaluated. The results are compared with available experimental data obtained in a water-oil mold model for various flow rates and immersion depths of the submerged entry nozzle. The water-oil interface pattern at the top of the mold is also investigated. Wave formation and evolution in time is simulated with a volume tracking method. The predicted flow field inside the mold exhibits quite satisfactory agreement with the corresponding measurements, whereas some quantitative differences are observed referring to the final wave amplitude at low casting speeds. Conclusions of scientific and engineering importance concerning both the computer algorithm and the mold performance are also drawn.

International Nuclear Information System (INIS)

A radiometric method of measuring the ratio of liquid and solid phases (crust thickness) in a continuous ingot for automation of the continuous steel casting process, has been proposed. The essence of the method is, that radiation flux, bearing information on the object tested, is transformed in a succession of electric pulses, which is processed afterwords for obtaining necessary information. In this case either the flux of non-scattered radiation, passed through the object, or the flux of single-scattered radiation reflected from the object is registered. Block-diagram and specifications of a radiometric device with the Co source of 50 gxequiv. Ra activity developed for this purpose are presented. The technique for calibration ob the device and the results of its tests, are described. It is shown, that introduction of such devices for the control crust thickness at the installations of continuous steel casting of metallurgical works would ...

Energy Technology Data Exchange (ETDEWEB)

In this project, graphite is used as a substitute for lead in order to maintain the machinability of plumbing components at the level of leaded brass. Graphite dispersed in Cu alloy was observed to impart good machinability and reduce the sizes of chips during machining of plumbing components in a manner similar to lead. Copper alloys containing dispersed graphite particles could be successfully cast in several plumbing fixtures which exhibited acceptable corrosion rate, solderability, platability, and pressure tightness. The power consumption for machining of composites was also lower than that of the matrix alloy. In addition, centrifugally cast copper alloy cylinders containing graphite particles were successfully made. These cylinders can therefore be used for bearing applications, as substitutes for lead-containing copper alloys. The results indicate that copper graphite alloys developed under this DOE project have a great potential to ...

Energy Technology Data Exchange (ETDEWEB)

The properties of cast basalt and alumina are examined. The ways in which these materials have been used in applications in coal preparation plants, for example in bunker and pipe linings where abrasion and corrosion resistant materials are required, are discussed.

Energy Technology Data Exchange (ETDEWEB)

Magnesium alloys have replaced resins as a material for the components of electronic products such as cell phone and notebook personal computer mainly, because of their lightness and rigidity. Thin walls, a complicated shape, and high appearance quality are all needed in the external parts. Die-casting and injection molding are the main method of manufacturing magnesium alloy parts. The optimal cast conditions and mold design have been investigated in order that a few defects such as surface cracks and mold cavities in casting parts would be reduced. Instead of cast, plastic forming technologies such as warm drawing and hot forging have been developed to form thinner walls and less defects. Plastic formability of magnesium alloy in hot working is dependent on a grain size of material. The material with fine grains has advantage of being formed at high strain rate. The characteristics of forming ...

Energy Technology Data Exchange (ETDEWEB)

Results are presented from studies on the quality of cast parts made by counterpressure casting of high-strength aluminum alloy AMKh-605, and Al-Cu-Mn-Cr alloys (5.6-6.4% Cu, 0.25-0.55% Mn, 0.20-0.55% Cr, 0.20-0.45% Ti, 0.08-0.25% Zr, less than or equal to0.25% Fe, less than or equal to0.25% Si, less than or equal to0.05% Mg). Chill castings were heat treated by quenching from 450/sup 0/C (20 hours) in water, aging at 160/sup 0/C for five hours with cooling in air. Fractograms of tensile specimens are presented. Scanning electron microscopy allows an ambiguous determination of the cause of failure of a part, be it at initial crystallization crack defects or burns, and also allows a relationship to be established between structure and mechanical properties.

Energy Technology Data Exchange (ETDEWEB)

The cupola is a furnace used for melting steel scrap, cast iron scrap, and ferroalloys to produce cast iron. Its main energy source is coal coke. It is one of the oldest methods of producing cast iron, and it remains the dominate method because of its simplicity and low fuel cost. Cupolas range in size from 18 inches to 13 feet in diameter, and can produce up to 100 tons per hour of cast iron. Although cupola melting has a long history, automatic control has been elusive because the process has been poorly understood. Most foundries rely on the intuition of experienced operators to make control decisions. The purpose of this work, which has been underway for three years of an anticipated four year program, is to develop a controller for the cupola using intelligent and conventional control methods. The project is a cooperative effort between the Idaho National Engineering and Environmental Laboratory, ...

Science.gov (United States)

Coke-fired cupola furnaces were improved and made suitable for the production of high-quality casting melts by numerous additional devices. Moreover, they were equipped with environmental protection systems with numerous dust separation devices and afterb...

Energy Technology Data Exchange (ETDEWEB)

Dimensional variability studies and published dimensional variability standards have been used by the foundry industry for years as an indicator of the casting process` ability to produce uniform parts. These studies are an extremely useful tool in the continuous ``dimensional dialogue`` between foundries and customers. The nature of these studies, and of the current tolerancing systems used by casting designers, leaves room for some misinterpretation and misuse of these study results. This paper contains two important discussions. The first part explains exactly what these studies represent. Following this is a brief explanation on dimensional and geometric tolerances and how they communicate dimensional requirements.

Energy Technology Data Exchange (ETDEWEB)

The effect of high-energy-density laser surface melting on the morphology and properties of a cast Ni-based superalloy containing 33 wt percent Mo and 17 wt percent W is investigated experimentally. Significant improvements in the hardness and the wear resistance in both dry and acid environments are atttributed to the elimination of segregation in the laser-treated zone, where solid solubility increases, crystalline structure becomes finer, and the fine dendritic, cellular dendritic, cellular, and plane-front solidification structures are evenly distributed.

British Library Electronic Table of Contents (United Kingdom)

Pilot industrial-scale testing of TSK-25 and TSK-10 compounds produced by NPP Tekhmet has been performed at Ruspolimet for siphon casting of 0.7?1.5-metric-ton ingots which are broader on the top (?flowers??) used for production of all-rolled rings; this is as an alternative to the existing process of pouring the steel into molds lubricated with petrolatum. The evaluation tests led to recommendation of the TSK-10 compound for industrial-scale testing; use of this compound enabled the petrolatum-lubricated steel casting process to be abandoned, thereby improving working conditions, and reducing rejects of the all-rolled ring products.

Energy Technology Data Exchange (ETDEWEB)

The distribution of graphite particles in graphite containing copper alloy was further improved very significantly using several procedures and technological modifications. The developed techniques attacked the graphite distribution problem in two ways. Realizing that clustering of very fine (5um) graphite particles is one of the two major problems, a pretreatment process has been developed using aluminum powders to deagglomerate graphite particles. Along with this, a two-stage stirring technique was used to first incorporate and then to distribute uniformly the deagglomerated particles in the melt. During this year, based on these developments, several components were cast to evaluate the castability of Cu alloy-graphite melts. In addition, machinability tests were done to clearly established that addition of graphite particles improve the machinability of copper MMC alloys over and above that of monolithic copper alloys. The results show that the machining chip ...

British Library Electronic Table of Contents (United Kingdom)

The properties of ZnO films were investigated as functions of annealing temperatures in H2/Ar and vacuum. The resistivities and mobilities of ZnO films decreased with increase of annealing temperatures in vacuum and H2/Ar ambients. However, the carrier densities of ZnO films increased with increase of annealing temperatures in vacuum and H2/Ar ambients. The resistivities of ZnO2 films annealed at 300degreeC were 2186cm and 798cm in H2/Ar and vacuum ambients, respectively. The resistivities of ZnO films annealed in vacuum and H2/Ar ambients at 600degreeC were similar with 0.040cm and 0.035cm, respectively. The hydrogen donor was more dominant than the oxygen vacancy or Zn interstitial donor in ZnO films annealed in ambient H2/Ar at low temperatures. The average optical transmission was >82%...

Energy Technology Data Exchange (ETDEWEB)

The Dental Investigation Service, USAFSAM, Brooks AFB, has outlined the need for a vacuum unit to be used in the Air Force dental clinics. The unit must be capable of effectively picking up mercury and at the same time not redistribute mercury vapors throughout the dental clinic during normal operations or mercury-spill situations. The Dental Investigation Service selected the MRS-3, Minuteman Mercury Recovery System, product of American Cleaning Equipment Corporation as the mercury vacuum to be used for T E. The USAF OEHL/ECH was requested by the Dental Investigation Service to perform the T E on the MRS-3 for possible health hazards due to exposures of mercury vapors.

CERN Document Server

We investigate the solar neutrino problem in the scenario of three generation neutrino oscillation hypothesis, taking into account other phenomenological constraints to the neutrino mixing and mass parameters.

Energy Technology Data Exchange (ETDEWEB)

A miniature x-ray source utilizing a hot filament cathode. The source has a millimeter scale size and is capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature source consists of a compact vacuum tube assembly containing the hot filament cathode, an anode, a high voltage feedthru for delivering high voltage to the cathode, a getter for maintaining high vacuum, a connector for initial vacuum pump down and crimp-off, and a high voltage connection for attaching a compact high voltage cable to the high voltage feedthru. At least a portion of the vacuum tube wall is fabricated from highly x-ray transparent materials, such as sapphire, diamond, or boron nitride.

International Nuclear Information System (INIS)

A high-average power (kW) infrared (IR) free-electron laser (FEL) is currently being commissioned for the Jefferson Laboratory FEL User Facility. The IR FEL is driven by a unique superconducting rf linac which is recirculated to recover electron beam power that is not radiated in the FEL. The design and installation of the vacuum system for the FEL involved particular attention to minimizing particulate contamination which could cause problems with the superconducting acceleration cavities and the high power FEL optics. Particulate contamination levels of all vacuum components were monitored during the cleaning process using laser scattering. Cleaning, transport, and installation procedures were developed to minimize the contamination of the complete system. We will summarize a data base we compiled of particulate contamination levels of the various components installed in the FEL vacuum system.

Energy Technology Data Exchange (ETDEWEB)

Vacuum arc with cathode spots on the cold electrode is widely used as a plasma generator in a such kind of devices like metal ion sources, plasma cathode electron guns, thing films deposition facilities and others. Most vacuum arc devices utilize a high voltage discharge across an insulator surface to provide a trigger plasma which in turn initiates the main arc discharge. Operation of vacuum arc in a repetitively pulsed mode required a stable triggering system for the long time. But with a discharge across the insulators the number of stable pulses is limited by 100,000 or little bit more. The better method for vacuum arc ignition is low pressure discharge. As shown in this paper it is possible to increase the lifetime of the ignition system in 10 times at least, but negative characteristic of this system is a relatively high pressure (about 0.1 mtorr). In some kinds of vacuum arc ...

International Nuclear Information System (INIS)

A technique has been developed for joining a large calcium fluoride crystal to a stainless-steel flange by means of a silver transition ring. The process involves both vacuum brazing using a copper-silver alloy and air brazing using silver chloride. This paper describes the procedure used in fabricating a high-vacuum leak-tight calcium fluoride window assembly.

International Nuclear Information System (INIS)

An experimental approach has been performed to ascertain the effectiveness of semi-solid strip casting using a horizontal twin roll caster. The demand for light-weight products with high strength has grown recently due to the rapid development of automobile and aircraft technology. One key to such development has been utilization of magnesium alloys, which can potentially reduce the total product weight. However, the problems of utilizing magnesium alloys are still mainly related to high manufacturing cost. One of the solutions to this problem is to develop magnesium casting-rolling technology in order to produce magnesium sheet products at competitive cost for commercial applications. In this experiment, magnesium alloy AZ31B was used to ascertain the effectiveness of semi-solid roll strip casting for producing magnesium alloy sheets. The temperature of the molten magnesium, and the roll speeds of the upper and lower ...

Energy Technology Data Exchange (ETDEWEB)

In order to judge the potential fluorescent lamp applications of various low-pressure positive column discharges it is necessary to measure the absolute power emitted in the ultraviolet region of the spectrum. For rare-gas discharges the principle emission occurs in the vacuum ultraviolet so that it is difficult to measure the radiant emittance (power per unit area) of the resonance radiation by standard methods. Two independent techniques are discussed for measuring the radiant emittance of positive column discharges in the vacuum ultraviolet. These techniques are used to study xenon positive column discharges at the resonance wavelength of 147 nm. The first method relies on the measurement of the resonance level density by absorption techniques. The effective decay rate of the resonance level is then determined by the simulation of resonance radiation transport. These two quantities are combined to yield the radiant emittance at 147 nm ...

Energy Technology Data Exchange (ETDEWEB)

The current status of the ZTH vacuum liner design is covered by this report. ZTH will be the first experiment to be installed in the CPRF (Confinement Physics Research Facility) at the Los Alamos National Laboratory and is scheduled to be operational at the rated current of 4 MA in 1992. The vacuum vessel has a 2.4 m major radius and a 40 cm minor radius. Operating parameters which drive the vacuum vessel mechanical design include a 300 C bakeout temperature, an armour support system capable of withstanding 25 kV, a high toroidal resistance, 1250 kPa magnetic loading, a 10 minute cycle time, and high positional accuracy with respect to the conducting shell. The vacuum vessel design features which satisfy the operating parameters are defined. The liner is constructed of Inconel 625 and has a geometry which alternates sections of thin walled bellows with rigid ribs. These composite sections span between ...

Energy Technology Data Exchange (ETDEWEB)

In order to enhance the mechanical properties of magnesium alloy (AZ31) sheet, an integrated sheet-making process including billet casting, extrusion and rolling was attempted. Microstructural analysis was carried out and the mechanical properties at each processing step were also investigated by tensile tests. By an extrusion process of ingot-processed billet, average grain size of billet was reduced from 91.2 to 28.2 {mu}m, and a further reduction in grain size to 16.9 {mu}m was obtained by subsequent rolling of extruded 5 mm thin slab. In the final step, a rolled sheet of 1 mm showed a remarkable refinement in grain size down to 8.8 {mu}m. Regarding mechanical properties, tensile strength and elongation for as-cast billet, as-extruded thin slab and as-rolled sheet increased from 189, 258 to 234 MPa, and from 13, 16.5 to 23%, respectively. (orig.)

International Nuclear Information System (INIS)

Microstructure characterization is important for controlling the quality of laser welding. In the present work, a detailed microstructure characterization by transmission electron microscopy was carried out on the laser welding cast Ni-based superalloy K418 turbo disk and alloy steel 42CrMo shaft and an unambiguous identification of phases in the weldment was accomplished. It was found that there are #gamma#-FeCrNiC austenite solid solution dendrites as the matrix, (Nb, Ti) C type MC carbides, fine and dispersed Ni_3 Al #gamma#' phase as well as Laves particles in the interdendritic region of the seam zone. A brief discussion was given for their existence based on both kinetic and thermodynamic principles.

British Library Electronic Table of Contents (United Kingdom)

The age hardening behavior of Al-4.5%Cu alloy composite reinforced with zircon sand particulates and produced by stir casting route has been investigated in different quenching media viz, water, oil, and salt brine solution (7wt%). Optical microscopy of the as cast alloy composite indicates that the matrix of the composite has the cellular structure. Copper rich CuAl2 precipitates have been found near particle matrix interface. The results of ageing demonstrate that the microhardness of age hardenable Al-Cu based alloy composites depend on the quenching medium in which they are heat treated. Salt brine quenching is faster as compared to water and oil, even if higher strength is obtained but cannot be used for complex shapes and thin sections where oil quenching is the alternative due to mi...

British Library Electronic Table of Contents (United Kingdom)

Scuffing damage is catastrophic and typically not self-healing. It severely affects the life and reliability of engineering components, such as cams, roller bearings, piston rings, cylinder bores and gears. Gray iron and 1080 steel are important materials for these extremely demanding structural components. There have been several scuffing studies done in the past with various types of steel and cast iron. However, in these studies there was no attempt to compare the scuffing resistance of cast iron and steel materials with similar matrices. In the present study, scuffing tests were performed with the matrices of gray iron and 1080 steel being fully pearlitic. This allows for a direct evaluation of the effect of the graphite flakes on scuffing resistance. The scuffing behavior for these ma...

International Nuclear Information System (INIS)

In order to substitute expensive cast titanium alloys by powder ones the possibility of introduction of powder additions by mechanical stock mixing is studied. It is shown that microstructure of powder alloys of Ti-Zr(1-9%) system is typical for one-phase cast #alpha#-alloys. The Ti-Mo(1-9%) and Ti-Nb(1-9%) system alloys have microstructure typical for two-phase (#alpha#+#beta#)-alloys. For homogeneous structure to be obtained the high temprature annealing is advisable after hot pressing. Alloying with Mo, Zr and Nb permits to increase considerable the strength of powder titanium products (at 9% Mo more than two times).

Energy Technology Data Exchange (ETDEWEB)

This paper summarizes the results of a long-term research project by SKBV which aimed to find ways of increasing spiral chute capacity while minimizing particle degradation, and also to extend the life of chute linings. Spiral chutes have been redesigned in such a way that chute speeds are considerably slower. The most wear-resistant and economic material for the inlet area was found to be slabs of tempered alloy cast steel, and for normal chute sections, cast basalt plates. Vertical rom bunkers can now be lined with thin cladding sections of GRC. Staple pit spiral chutes have been considerably improved in respect to wear and abrasion by the use of toughened steel as the chute lining material. Several of the innovations developed during the course of the research project are in use in West German mines and some have also been introduced abroad. (In German)

Energy Technology Data Exchange (ETDEWEB)

As a part of the WE-NET project, the tanker for liquid hydrogen transport was studied. In fiscal 1996, some experiments and numerical analyses were proposed which are necessary to solve technological issues extracted in fiscal 1995 for heat insulation structure. The issue was roughly classified into vacuum and non-vacuum insulation, and their basic functions and required performance were arranged. Boil-off rate of 0.2-0.4%/d was targeted. The insulation system which applies polyurethane form (PUF) to tank surfaces and injects atmospheric N2 gas into the surrounding hold space, could achieve the targeted insulation performance by PUF of 1m in thickness. The system of vacuum panel insulation and atmospheric N2 gas injection into a hold space required the panel of 500mm in thickness because of the large effect of metallic outer panel material. The system of vacuum hold and PUF panels was faced with the ...

International Nuclear Information System (INIS)

On all steam turbines operating with condensation the air leakage penetrating from the part of the plant which is under vacuum must be eliminated, in order to maintain the vacuum created by physical conditions. In order to attain effective air bleed-off, the water-steam-air mixture is conveyed via the super-cooling bundles in the condenser. In this way the steam partial pressure decreases and the air partial pressure increases at a constant condenser pressure. In this procedure the mixture is supercooled by about 4"0C compared with the saturate steam temperature appertaining to the condenser pressure. The values of volume of air leakage are the result of a year's experience on existing plant. (orig.).

CERN Document Server

One hope to solve the cosmological constant problem is to identify a symmetry principle, based on which the cosmological constant can be reduced either to zero, or to a tiny value. Here, we note that requiring that the vacuum state is Lorentz invariant significantly reduces the theoretical value of the vacuum energy density. Hence, this also reduces the discrepancy between the observed value of the cosmological constant and its theoretical expectation, down from 123 orders of magnitude to 56 orders of magnitude. We find that, at one loop level, massless particles do not yield any contribution to the cosmological constant. Another important consequence of Lorentz symmetry is stabilization of the gravitational hierarchy: the cosmological constant (divided by Newton's constant) does not run as the quartic power of the renormalization group scale, but instead only logarithmically.

British Library Electronic Table of Contents (United Kingdom)

We have measured time-resolved laser-induced incandescence of flame-generated soot under high-vacuum conditions (4.1?10?6 mbar) at an excitation wavelength of 532 nm with laser fluences spanning 0.06?0.5 J/cm2. We generated soot in an ethylene/air diffusion flame, introduced it into the vacuum system with an aerodynamic lens, heated it using a pulsed laser with a spatially homogeneous and temporally smooth laser profile, and recorded LII temporal profiles at 685 nm. At low laser fluences LII signal decay rates are slow, and LII signals persist beyond the residence time of the soot particles in the detection region. At these fluences, the temporal maximum of the LII signal increases nearly linearly with increasing laser fluence until reaching a plateau at ?0.18?J/cm2. At higher fluences, th...

International Nuclear Information System (INIS)

It is shown that it is necessary to take into account locality of the analysis and to introduce additional corrections for partial capture of matrix and fluorescent subexcitation by matrix during quantitative X-ray spectral microanalysis of finely dispersed materials. Cast two-phase (#alpha#+#beta#) titanium alloy VT3-1 is chosen as an investigation object.

Science.gov (United States)

Silicone-rubber washers function as damping and articulating elements in cast-aluminum spacers that separate bundle subconductors in each phase of extra-high-voltage transmission lines. Spacer/dampers are located every 3 ft. along transmission lines on Canada's first operational 500 and 735 kV system.

Wastenet

... Zahra-Kingrsquo;s practice utilizes a range of media including textiles, metal casting, glass, sound, film and photography. Qualifications English Major from BA (Social Science) 1991; BA(Visual Arts) 1991; Grad. Dip. (Fine Art - Printmaking) 1993; Candidate for MFA 2001; Ph.D 2005. School of Art Research Clusters Art and Environmental Sustainability Art, ...

Energy Technology Data Exchange (ETDEWEB)

In this work a Ni-based superalloy GMR 235 was investigated. We determined convenient metallographic methods for preparation of bulk metallographic specimens, extraction carbon replicas, transparent metallic foils and minor phase extraction. In addition, the alloy microstructure was characterised using different metallographic techniques. (orig.)

International Nuclear Information System (INIS)

This paper reports about in-situ corrosion studies on selected materials for long-term resistant high-level waste (HLW) packagings acting as a barrier in a rock salt repository. The materials (Ti 99.8-Pd, Hastelloy C4 and five iron-base materials) were investigated in heated boreholes in the Asse salt mine under simulated HLW disposal conditions prevailing in normal operation of repository and in certain accident scenarios. The experiments under normal operating conditions were performed at temperatures of 120 deg. C to 210 deg. C (vertical temperature profile in the boreholes) without and with gamma irradiation (3#centre dot#10"2 Gy/h, Co-60 source) within the framework of the German/US Brine Migration Test. In these experiments only small amounts of migrated brine inclusions (NaCl-rich) from the rock salt were present as corrosion medium. In the experiments carried out under simulated accident conditions with intrusion of larger amounts of NaCl brine into the HLW boreholes the ...

Energy Technology Data Exchange (ETDEWEB)

In order to investigate the extrusion characteristics of magnesium alloy (AZ31), a computer simulation was attempted. Tensile properties of as-cast billet with different strain rates were incorporated into the simulation. The results showed a great change in distribution of stress and strain at near die region by the ram travel. It was found that the average grain size at longitudinal edge of the extruded sheet was smaller than that at center region, which might be attributed to recrystallization caused by severe plastic deformation. (orig.)

British Library Electronic Table of Contents (United Kingdom)

An eddy current probe of the level of molten metal is considered for a sectional machine of continuous casting of steel. The advantages of electromagnetic probes of the level over radiometric ones lie in their insensitivity to the layer of dross and high speed. The results and directions of further studies are given.

UK PubMed Central (United Kingdom)

Total thyroidectomy involving the adjacent structures of the trachea can cause tracheal damage such as early tracheal necrosis. The authors describe the first case of anterior tracheal necrosis following...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Various nylons including nylon 6, nylon 66, nylon 610 and nylon 12 in the forms of fiber and film were irradiated with the gamma-ray from Co-60 at the dose rate of 0.12 Mrad/hr in the atmosphere of oxygen at 7 kg/cm/sup 2/ and at the room temperature. The irradiation in vacuum on the same specimens was performed at 0.5 Mrad/hr. The tensile properties and the gel fraction of the irradiated nylon samples were measured, and the radiation resistance of the nylons against the irradiation at low dose rate was estimated. From the experimental results, it became clear that in the case of irradiation in vacuum, all the nylons were durable to the irradiation of 250 Mrad or more, and nylon 6 was more durable than nylon 12, and in the case of irradiation in pressurized oxygen, the radiation resistance of the nylons decreased to one-tenth as compared with that in vacuum, and contrary to that in vacuum, nylon 12 was ...

Energy Technology Data Exchange (ETDEWEB)

Progress is reported in fabrication and coating activities being conducted for the weapons program, nuclear test program, nuclear design program, magnetic fusion program, and miscellaneous applications. (DLC)

Science.gov (United States)

... Figure 3 shows on-orbit (ie, vacuum) frequency aging rates for Milstar rubidium (Rb) clocks, GPS Block IIR Rb clocks, and GPS Block IIA Rb clocks. ...

Energy Technology Data Exchange (ETDEWEB)

This paper describes the technical design and performance of the diagnostic system installed in the tokamak TCABR to measure parameters of the plasma edge. The system consists of four Langmuir probes under remote control. (author)

International Nuclear Information System (INIS)

Plasma surface interactions in tokamaks are known to create significant quantities of dust, which settles onto surfaces and accumulates in the vacuum vessel. In ITER, a loss of vacuum accident may result in the release of dust which will be radioactive and/or toxic, and provides increased surface area for chemical reactions or dust explosion. A new method of analysis has been developed for modeling dust resuspension and transport in loss of vacuum accidents. The aerosol dynamic equation is solved via the user defined scalar (UDS) capability in the commercial CFD code Fluent. Fluent solves up to 50 generic transport equations for user defined scalars, and allows customization of terms in these equations through user defined functions (UDF). This allows calculation of diffusion coefficients based on local flow properties, inclusion of body forces such as gravity and thermophoresis in the convection term, and user defined ...

UK PubMed Central (United Kingdom)

The recovery of schistosome cercariae from natural waters has been limited by variations in turbidity and in the accuracy of recovery with different techniques. A modification of the Rowan vacuum paper...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Additional results using a calorimetric technique for measuring the total hemispherical emittance of pipe surfaces from 400 to 600 K are described. Two different Pyrex pipe enclosures were used, one of 15 cm i.d. and the other of 30 cm i.d. An error analysis showed that the larger diameter Pyrex pipe should have a smaller error, but the difference was negligible for the 4.4-cm test pipe diameter used. Measurements on a short length of a previously-measured pipe agreed with earlier measurements, but only over the temperature range of the measurements. While the technique normally uses a vacuum to minimize nonradiative heat transfer, measurements were done succesfully with an argon atmosphere in a closed system. A nickel-plated pipe, measured first in a vacuum and then in an argon atmosphere, allowed calculation of an effective convective heat-transfer coefficient for use with test pipes of unknown emittances. Measurements done with an atmosphere ...

Energy Technology Data Exchange (ETDEWEB)

The choice of vacuum state for a quantum scalar field propagating in a de Sitter spacetime (massive and arbitrarily coupled to the gravitational field) is discussed. The problem of finite-time initial conditions for the mode functions is analyzed, as well as how these determine the vacuum state of the quantum system. The principle guiding the choice of vacuum state is the following: one wants the vacuum contribution to the energy-momentum tensor to contain all the ultraviolet divergent terms, so that the particle creation terms are finite, and covariantly conserved. There is a suitable set of modes (instantaneous adiabatic basis) in which this splitting of the expectation value of the energy-momentum tensor can be carried out. Numerical results are presented for different finite-time initial conditions (m = 0.6, {zeta} = 1/6). The nature of the particle creation effect is described and its relationship ...

Energy Technology Data Exchange (ETDEWEB)

The vacuum polarization splitting of the M-shell states in muonic hydrogen can have a profound influence on the muonit de-excitation cascade in deuterium and tritium targets. The cascade also shows sensitive dependence on the precise rate of transfer processes between certain excited muonic deuterium and tritium atoms. Recent experimental data, where a much greater population of the (d..mu..) qs state (1/sub 1//sub //sub s/) was found than previously predicted, can be explained if the transfer rates from the (d..mu..) M-shell are assumed to be strongly suppressed.

Energy Technology Data Exchange (ETDEWEB)

The fatigue properties of EP539LM alloy with an Al-Nb-Si fused slurry coating and a Co-Cr-Al-Y electron-beam coating are investigated experimentally in vacuum and in air at 900 C. It is found that the protective coatings reduce the fatigue life of the specimens both in vacuum and in air, with the electron-beam coating affecting the fatigue life of the alloy to a lesser degree than the fused slurry coating. The negative effect of the coatings on the fatigue life of the alloy is attributed largely to the properties of the coating material. 7 references.

International Nuclear Information System (INIS)

The nitric acid solution dissolving nuclear fuel material is transferred with the three way valve called VCV (VCV: vide-casse-vide in Fr.) using vacuum in the Tokai Reprocessing Plant. The initial VCV was not reliable because it had broken with in 1 or 2 years. The cause of failure was damage of the plastic diaphragms in the moving parts. Then, the new VCV valve with stainless-steel bellows was developed. There is no failure in moving parts in 20 years, therefore reliability is significantly improved. (author)

CERN Document Server

If quantum fields exist in extra compact dimensions, they will give rise to a quantum vacuum or Casimir energy. That vacuum energy will manifest itself as a cosmological constant. The fact that supernova and cosmic microwave background data indicate that the cosmological constant is of the same order as the critical mass density to close the universe supplies a lower bound on the size of the extra dimensions. Recent laboratory constraints on deviations from Newton's law place an upper limit. The allowed region is so small as to suggest that either extra compact dimensions do not exist, or their properties are about to be tightly constrained by experimental data.

Energy Technology Data Exchange (ETDEWEB)

We consider the dynamics toward the initial singularity of Bianchi type IX vacuum and orthogonal perfect fluid models with a linear equation of state. The 'Bianchi type IX attractor theorem' states that the past asymptotic behavior of generic type IX solutions is governed by Bianchi type I and II vacuum states (Mixmaster attractor). We give a comparatively short and self-contained new proof of this theorem. The proof we give is interesting in itself, but more importantly it illustrates and emphasizes that type IX is special, and to some extent misleading when one considers the broader context of generic models without symmetries.

CERN Document Server

We consider the dynamics towards the initial singularity of Bianchi type IX vacuum and orthogonal perfect fluid models with a linear equation of state. The `Bianchi type IX attractor theorem' states that the past asymptotic behavior of generic type IX solutions is governed by Bianchi type I and II vacuum states (Mixmaster attractor). We give a comparatively short and self-contained new proof of this theorem. The proof we give is interesting in itself, but more importantly it illustrates and emphasizes that type IX is special, and to some extent misleading when one considers the broader context of generic models without symmetries.

Energy Technology Data Exchange (ETDEWEB)

A Vacuum Circuit Breaker demonstrated its ability to interrupt short circuits with faster than normal rates of rise of Transient Recovery Voltage (TRV) at levels greater than those produced by most transformer secondary faults. Two recent exploratory test programs evaluated the interrupting ability of a 15kV Vacuum Circuit Breaker containing interrupters of the rotating arc type with contacts made from a Chromium-Copper powder metal mixture. The interrupting conditions covered a wide range of currents from 10% to 130% of the 28kA rated short circuit current of the tested circuit breaker and a wide range of TRV rates of rise, including the relatively slow rate of rise, normally used in testing and found in most indoor circuit breaker applications; two faster rates of rise equaling and exceeding those found in a known power plant transformer secondary protection application; and the fastest rates of rise possible in the laboratory which exceed ...

Energy Technology Data Exchange (ETDEWEB)

Puffer gas circuit breaker used widely in interrupters with from middle capacity to large capacity does not keep away from reacting force of the puffer with high functions in principle and there is a limit in low operation. In this study, aiming at low operation of the interrupters, in order to clarify the basic motions of hybrid circuit interrupter that is the combination of thermal puffer gas circuit breaker and vacuum circuit breaker, the interrupting ability of simple thermal puffer gas breaker and the voltage sharing characteristics in the cases of series connection with the vacuum circuit breaker are studied. The results of the study are as follows. In comparing terminal short circuit accident interrupting ability of single flow typed thermal puffer gas breaker with that of double flow typed thermal puffer gas breaker, the interrupting ability of the double flow typed thermal puffer gas breaker may be improved. It is also clarified that ...

Energy Technology Data Exchange (ETDEWEB)

The intention of this study is to show the high potential of remote sensing data to keep an eye on longterm processes in large regions with widespread tasks and questions. The results of two projects (sponsored by the BMBF - Ministry of Education and Science, Germany and the country of Saxony-Anhalt) are taken into account to give an impression of the chances provided by the application of hyperspectral airborne scanner data and satellite images. So these two projects focus at the applicability of various methods to use remote sensing data for a long- term monitoring of former lignite open-cast mining areas. Apart from the traditional pixelorientated analysis, the application and combination of new object orientated methods (e.g. segmentation, texture analysis) were investigated to distinguish between the following typical vegetation types: Spontaneous revegetation of plant communities; reforestation areas; recultivated grass seeding areas; area patterns of ...

Energy Technology Data Exchange (ETDEWEB)

The results of these investigations can be summarised as follows: At simulated operating stress most naturally occuring faults in welded- and cast iron parts develop cracks and can be assessed for reliability under fatigue-,creep- and creep fatigue behaviour according to the laws of fracture mechanics. The empirically determined correlation between the real fault size and the ultrasonic inspection results (height of echo, echo dynamics, sound weakening) lead to better assessment of real fault extension in turbine components. It is very important to adapt the method of inspection and assessment to the type of possible fault.(orig.) [German] Die bei diesen Untersuchungen ermittelten Ergebnisse lassen sich wie folgt zusammenfassen: - Die Mehrzahl der untersuchten natuerlichen Fehlstellen in den Schmiede- und Gussstuecken verhalten sich unter den simulierten Betriebsbeanspruchungen rissartig und sind damit mittels den bruchmechanischen Gesetzen in ihrem ...

British Library Electronic Table of Contents (United Kingdom)

One of the major limitations of the nickel (Ni) - yttria-stabilized zirconia (YSZ) anode support for solid oxide fuel cells (SOFC) is its low capability to withstand transients between reducing and oxidizing atmospheres (''RedOx'' cycle), owing to the Ni-to-NiO volume expansion. This work presents results on different anode supports fabricated by tape casting. Three compositions are prepared, as the outcome of a preceding design of experiment approach. The NiO proportion is 40, 50 and 60wt% of the anode composite. The anode support characteristics like shrinkage during sintering, in-situ conductivity at high temperature, electrochemical performance and tolerance against RedOx cycles have been measured. Performance up to 0.72Wcm^-^2 (0.62V, 800^oC) is recorded for the 60wt% NiO sample on sm...

Science.gov (United States)

Experimental trials of autogenous deep penetration welding between dissimilar cast Ni-based superalloy K418 and alloy steel 42CrMo flat plates with 5.0 mm thickness were conducted using a 3 kW continuous wave (CW) Nd:YAG laser. The influences of laser output power, welding velocity and defocusing distance on the morphology, welding depth and width as well as quality of the welded seam were investigated. Results show that full keyhole welding is not formed on both K418 and 42CrMo side, simultaneously, due to the relatively low output power. Partial fusion is observed on the welded seam near 42CrMo side because of the large disparity of thermal physical and high-temperature mechanical properties of these two materials. The microhardness of the laser-welded joint was also examined and analyzed. It is suggested that applying negative defocusing in the range of Raylei length can increase the welding depth and improve the coupling efficiency of the laser materials ...

Energy Technology Data Exchange (ETDEWEB)

The exposure of heat-resistant alloys to high temperature can significantly change their mechanical properties. This paper presents and analyzes data on the effect of thermal exposure on the tensile and impact behavior of three cast materials -- the HK-40, HP-50, and 21Cr-32Ni-Fe alloys -- and of wrought material -- Alloy 800. The changes in tensile and impact properties caused by high-temperature exposure are reviewed. Reasons for these property changes and needs for considering them in the design, operation, and life assessment of high-temperature equipment are discussed.

Energy Technology Data Exchange (ETDEWEB)

16 papers are presented covering: remote sensing - an aid to environment management; remote sensing application; monitoring environmental changes over iron ore mining areas; monitoring and management of environmental degradation due to geological factors; use of Landsat multispectral scanner data in environmental monitoring; geotechnical engineering problems with abandoned limestone mines; photogrammetric monitoring of mining environment; slope monitoring in open cast mines using close range remote sensing method; geobotanical remote sensing and mineral prospecting; geographical information in study of geo-environment through remote sensing; and alteration mapping in cuprite mining district.

Energy Technology Data Exchange (ETDEWEB)

Contents include: countermeasures to save energy of sintering plant and future plans in fukuyama works; improvement of surface quality of continuous-casting slab; development of direct quenching and tempering type HT80 steel with good weldability; numerical analysis of fluid flow in a geothermal reservoir; the finite-element calculation of turbulent flow using the universal law of the wall; development of PC 4 dual fuel engine; design of industrialized housing; Computer-aided Navigation system (CANSY); and new production control system in Fukuyama Works.

Energy Technology Data Exchange (ETDEWEB)

A compliant cantilevered three-dimensional micromold is provided. The compliant cantilevered micromold is suitable for use in the replication of cantilevered microparts and greatly simplifies the replication of such cantilevered parts. The compliant cantilevered micromold may be used to fabricate microparts using casting or electroforming techniques. When the compliant micromold is used to fabricate electroformed cantilevered parts, the micromold will also comprise an electrically conducting base formed by a porous metal substrate that is embedded within the compliant cantilevered micromold. Methods for fabricating the compliant cantilevered micromold as well as methods of replicating cantilevered microparts using the compliant cantilevered micromold are also provided.

Energy Technology Data Exchange (ETDEWEB)

LaAlO{sub 3} and CeO{sub 2} films have been successfully grown using sol-gel precursors. LaAlO{sub 3} precursor solution has been prepared from a metal alkoxide route and spun-cast on a SrTiO{sub 3} (100) single crystal to yield an epitaxial film following pyrolysis at 800{degrees}C in a rapid thermal annealer. A CeO{sub 2} precursor solution has been made using both an aqueous and an alkoxide route.

Energy Technology Data Exchange (ETDEWEB)

A series of short articles discusses: use of a chemically bonded ceramic composite liner, WellerDensit, to protect the steel surface of pulverizer classifier cones; use of a fused cast basalt liners developed by Abresist Corp. in pipes for transporting coal and ash; a survey completed by the National Energy Technology Laboratory to identify causes of outages and other concerns expressed by PC and FBC boiler operators; and Temp-Age, Early Visc-Age and Modern Visc-Age systems for controlling the viscosity of heavy fuel oil to maintain proper combustion. 7 figs.

Energy Technology Data Exchange (ETDEWEB)

Using ultrapure samples of polyacrylonitrile (PAN) of 485,000 or 150,000 average molecular weight solution cast in dimethylformamide, the dc conductivity (sigma) of pyrolyzed PAN (PANP) films has been studied for pyrolysis temperatures (T/ sub p/) of 280 to 435/sup 0/C. Conductivity measurements made during pyrolysis indicate the onset of a dramatic increase in sigma for T/sub p/ of 390 to 435/sup 0/C. Conductivities as high as 5 (ohm-cm)/sup -1/ have been observed for T/sub p/ < 435/sup 0/C.

Energy Technology Data Exchange (ETDEWEB)

Magnesium cast parts as well as indirectly and hydrostatically extruded profiles were used in order to investigate the influence of different microstructures on the damping behaviour of magnesium AZ-alloys. Especially, hydrostatic extrusion leads to a significant grain refinement in the extruded profile compared to indirect extrusion. Strain dependent damping measurements were carried out at room temperature using alloys AZ31, AZ61 and AZ80. Damping was determined as the logarithmic decrement of free bending beam vibrations. The results of these measurements after indirect and hydrostatic extrusion are shown and discussed. (orig.)

Energy Technology Data Exchange (ETDEWEB)

A compliant cantilevered three-dimensional micromold is provided. The compliant cantilevered micromold is suitable for use in the replication of cantilevered microparts and greatly simplifies the replication of such cantilevered parts. The compliant cantilevered micromold may be used to fabricate microparts using casting or electroforming techniques. When the compliant micromold is used to fabricate electroformed cantilevered parts, the micromold will also comprise an electrically conducting base formed by a porous metal substrate that is embedded within the compliant cantilevered micromold. Methods for fabricating the compliant cantilevered micromold as well as methods of replicating cantilevered microparts using the compliant cantilevered micromold are also provided.

Energy Technology Data Exchange (ETDEWEB)

An analysis of the current state of track-laying operations in open-cut mines is given and their labor intensive nature is noted. The lag in the technological development of mechanization equipment for track laying and repair operations is noted. Results are given from developments by the Scientific Research Institute of Open-Pit Mining Operations in the field of mobile transportation technology and promising modular route design. Also examined are the problems of improving the routing bases in the industry. The absence of factories for manufacturing transportation technology and equipment is reflected most evidently in the technical and cost characteristics of coal production by an open-cut method and requires immediate solution.

Energy Technology Data Exchange (ETDEWEB)

The effects of carbon inoculation by C{sub 2}Cl{sub 6} addition were investigated using commercial AZ31 magnesium alloy. The additions of C{sub 2}Cl{sub 6} to AZ31 magnesium alloy significantly reduce the grain size from 280 {mu}m to about 120 {mu}m and the tensile properties are also increased due to grain refinement. EPMA analysis shows that Al-C-O compounds are formed in the castings which are considered to function as nucleants. (orig.)

Energy Technology Data Exchange (ETDEWEB)

The Minami-Iwaki trunk line now under construction by Tokyo Electric Power Company is an UHV transmission line which covers 130km from the central region of the Abukuma highlands, Fukushima Prefecture, through the northern ridge of the Kanto Plain to Imaichi City, Tochigi Prefecture and has 235 steel towers. About 30% of the ground along the above route is mainly layers of sand and gravel. Accordingly it has become urgent to design rationally the pile foundations in the sand and gravel layers. Hence the company has studied an estimation method of the ultimate bearing power of cast-in-place piles penetrating the sand and gravel layers and the displacement of pile heads. In this report, the result of the above study is described. The company has so far used the equations in accordance to the Meyerhof equations for the estimations of the ultimate bearing power and this time, this equations have been examined for its application to the sand and gravel layers, and for ...

Science.gov (United States)

Lunar resource utilization has focused principally on the extraction of oxygen from the lunar regolith. A number of schemes have been proposed for oxygen extraction from Ilmenite and Anorthite. Serendipitously, these schemes have as their by-products (or more directly as their "waste products"), materials needed for the fabrication of thin film silicon solar cells. Thus lunar surface possesses both the elemental components needed for the fabrication of silicon solar cells and a vacuum environment that allows for vacuum deposition of thin film solar cells directly on the surface of the Moon without the need for vacuum chambers. In support of the US space exploration initiative a new architecture for the production of thin film solar cells on directly on the lunar surface is proposed. The paper discusses experimental data on the fabrication and properties of lunar glass substrates, evaporated lunar regolith thin films ...

International Nuclear Information System (INIS)

Potassium deposition in ultrahigh vacuum on 12-(3-thienyl)dodecanethiol monolayers assembled on gold surfaces has been investigated using X-ray and ultraviolet photoelectron spectroscopies (XPS and UPS). Angle-resolved XPS indicates that initially deposited potassium penetrates the self-assembled monolayer (SAM) and diffuses to the SAM/Au interface. Even after large metal doses, the presence of thiophene ring valence electronic states in the UPS spectra confirms that most of the thiophene rings (at the SAM/vacuum interface) are not covered by potassium. The binding energy shifts of the thiophene ring valence states and the C1s and thiophene S2p peaks, referenced to the Fermi level, are due to the work function changes of the gold substrate. This indicates that these electronic states are pinned to the vacuum level, in contrast to the thiolate S2p orbital, which is pinned to the Fermi level. For large potassium doses, the ...

International Nuclear Information System (INIS)

In vacuum arcs of interest for ion deposition, in which a magnetic filter is used, significant plasma rotation about the filter axis can develop. In the present work we present experimental evidence and simplified models to interpret relatively fast rotation of plasma generated in a pulsed vacuum arc with a straight magnetic filter and with a magnetic field strength in the range 52-430 G. The plasma rotation is produced in the first part of the filter (the driving region) where either the expanding or the contracting plasma encounters a mainly axial magnetic field. In the next part of the filter (the rotation region) a quasi-equilibrium is achieved and the plasma does not evolve further significantly. A rigid-rotor type of equilibrium is considered to model the rotation region, with experimentally obtained parameters, and a simple model is employed in the driving region to quantify the magnitude of the plasma rotation. It is found that at the ...

International Nuclear Information System (INIS)

The dependencies that limit high frequency operation of a vacuum microelectronic grating free-electron laser are examined. The important parameters are identified as the electron beam energy, emittance, and generalized perveance. The scaling of power with emittance and frequency is studied in the far-infrared spectral range using a modified scanning electron microscope (SEM) and submillimeter diffraction gratings. The SEM is suited to the task of generating and positioning a low emittance (10"-"2#pi#-mm-mrad), low current (100 #mu#A), but high current density (50-500 A cm"-"2) electron beam. It has been used to demonstrate the spontaneous emission process known as the Smith-Purcell effect. A vacuum microelectronic grating free-electron laser has the potential of generating radiation throughout the entire far-infrared spectral range which extends from approximately 10 to 10"3#mu#m. An introduction to the theory, initial results, and details of ...

International Nuclear Information System (INIS)

During unit wise conditioning of unit 8, the vacuum started deteriorating inside the tube after a spark. The RGA reading was taken and it was found out that residual gas inside tube was sulphur hexafluoride. A leak was detected in second tube of unit number eight in between electrode 6 to 8. Leak was sealed with the sealant. Again leak check was done and no leak was found. The tank was closed and conditioning was started again. During the same unit number eight conditioning, leak developed again followed by a spark. So the damaged tube was replaced with a new accelerator tube. During the installation time the alignment of the machine was taken care. Again leak checking was done and the tube was baked properly. The tank was closed again and this particular unit was conditioned for about four days. The maximum voltage it has attained was 1.1 MV. (author)

CERN Document Server

We present experimental studies on the photoionization and photodissociation processes (photodestruction) of gaseous amino acids and nucleobases in interstellar and interplanetary radiation conditions analogs. The measurements have been undertaken at the Brazilian Synchrotron Light Laboratory (LNLS), employing vacuum ultraviolet (VUV) and soft X-ray photons. The experimental set up basically consists of a time-of-flight mass spectrometer kept under high vacuum conditions. Mass spectra were obtained using photoelectron photoion coincidence technique. We have shown that the amino acids are effectively more destroyed (up to 70-80%) by the stellar radiation than the nucleobases, mainly in the VUV. Since polycyclic aromatic hydrocarbons have the same survival capability and seem to be ubiquitous in the ISM, it is not unreasonable to predict that nucleobases could survive in the interstellar medium and/or in comets, even as a stable cation.

British Library Electronic Table of Contents (United Kingdom)

The light-emitting properties of cubic silicon carbide films grown by vacuum vapor phase epitaxy on Si(100) and Si(111) substrates under conditions of decreased growth temperatures (T gr ? 900?700?C) have been discussed. Structural investigations have revealed a nanocrystalline structure and, simultaneously, a homogeneity of the phase composition of the grown 3C-SiC films. Photoluminescence spectra of these structures under excitation of the electronic subsystem by a helium-cadmium laser (?excit = 325 nm) are characterized by a rather intense luminescence band with the maximum shifted toward the ultraviolet (?3 eV) region of the spectral range. It has been found that the integral curve of photoluminescence at low temperatures of measurements is split into a set of Lorentzian components. Th...

British Library Electronic Table of Contents (United Kingdom)

In this study three types of scanning electron microscopes were used for the size determination of spermatozoa of sterlet Acipenser ruthenus - high vacuum scanning electron microscope (SEM, JEOL 6300), environmental scanning electron microscope (ESEM, Quanta 200 FEG), field emission scanning electron microscope (FESEM, JEOL 7401F) with cryoattachment Alto 2500 (Gatan) and transmission electron microscope (TEM, JEOL 1010). The use of particular microscopes was tied with different specimen preparation techniques. The aim of this study was to evaluate to what degree the type of used electron microscope can influence the size of different parts of spermatozoa. For high vacuum SEM the specimen was prepared using two slightly different procedures. After chemical fixation with 2.5% glutaraldehyde...

International Nuclear Information System (INIS)

The present article will review recent advances in focused ion beam (FIB) technology. With increasing demands for scale of integration, microfabrication technology is becoming more important and various new microfabrication tools and processing techniques are desired. FIB is one of the promising tools for future microfabrication technology. This provides maskless patterning capability, which is of importance for process simplification, nanofabrication and in the development of in situ vacuum processing. In situ vacuum processing systems are being developed by combining FIB and a molecular beam epitaxy system. Radiation damage may limit applications of FIB. However, it was demonstrated that low energy FIB (<1 keV) with very high brightness was reached and promising results for low damage processing have been obtained. (orig.).

International Nuclear Information System (INIS)

The KSTAR cooling water system (CWS) consists of a primary cooling water system (PCWS), a secondary cooling water system (SCWS), and a de-mineralizing and de-ionized water system (DIWS). The PCWS cooling loops have been made for the poloidal field (PF) and toroidal field (TF) magnet power supplies (MPS), vacuum vessel (VV), electron cyclotron heating (ECH), ion cyclotron heating (ICRH), vacuum pumps, diagnostics, helium facility, etc. The CWS had been done individual commissioning of each system to confirm the design specifications by the end of 2006 and had gradually begun operation for the KSTAR ancillary devices by March 2008

International Nuclear Information System (INIS)

This paper discusses the mechanisms of gas breakdown at low values of pressure and inter-electrode gap, i.e. in the vicinity of the Paschen minimum. In this area of pressure and inter-electrode gap values, breakdown occurs either through gas or vacuum mechanisms, and also the so called anomalous Paschen effect appears. Electrical breakdown of electropositive, electronegative and noble gases has been investigated theoretically, experimentally and numerically. Based on the results obtained, regions in which particular breakdown mechanisms appear have been demarcated. Special attention has been devoted to the anomalous Paschen effect as well as to the avalanche vacuum breakdown mechanism.

International Nuclear Information System (INIS)

Within the framework of the Bianchi type-IX homogeneous space, we set up a system of coupled equations for the cosmic scale factors, scalar field, and radiative energy density. At the tree level, the equations are written in a self-consistent, Hartree-Fock form. For phi"4 theory, the system of nine first-order differential equations is solved numerically for a varying ratio of the energy of anisotropy to the vacuum energy. As the vacuum energy increases, there appears to be less reheating, since the energy of anisotropy is more efficiently converted into isotropic expansion. If the energy of anisotropy is large enough, the inflationary phase is prevented. In this case, a series of cosmological phase transitions will take place each time the square of the effective mass changes its sign.

Science.gov (United States)

A full-scale model of a rigid sectorial ring and a set of bellows which was covered with a temperature control layer and a coolant supply equipment was constructed to verify the adequacy of the heating and cooling system designed for JT-60. To cool and heat it effectively and to decrease the temperature differences among the various parts in the vacuum vessel, heater units and cooling pipes were located on the surface of the ring. The temperature control layer is to heat the vessel to 500/degree/sub //C within 70 hours and to maintain it at the temperature for 48 hours for simulating the state of bakeout. Subsequently the vessel is cooled down within about the same time as in heating. Prior to the series of tests, numerical analyses were performed to predict the cooling and heating efficiencies on the model and to examine the method of the temperature regulation.

British Library Electronic Table of Contents (United Kingdom)

By assuming that not only counter-ions but DNA molecules as well are thermally distributed according to a Boltzmann law, we propose a modified Poisson-Boltzmann equation, at the classical level, as a starting point to compute the effects of quantum fluctuations of the electric field on the interaction among DNA-cation complexes. The latter are modeled here as infinite one-dimensional wires (?-functions). Our goal is to single out such quantum-vacuum-driven interaction from the counterion-induced and water-related interactions. We obtain a universal, frustration-free Casimir-like (codimension 2) interaction that extensive numerical analysis show to be a good candidate to explain the formation and stability of DNA aggregates. Such Casimir energy is computed for a variety of configurations of...

CERN Document Server

Disorder on the string theory landscape may significantly affect dynamics of eternal inflation leading to the possibility for some vacua on the landscape to become dynamically preferable over others. We systematically study effects of a generic disorder on the landscape starting by identifying a sector with built-in disorder -- a set of de Sitter vacua corresponding to compactifications of the Type IIB string theory on Calabi-Yau manifolds with a number of warped Klebanov-Strassler throats attached randomly to the bulk part of the Calabi-Yau. Further, we derive continuum limit of the vacuum dynamics equations on the landscape. Using methods of dynamical renormalization group we determine the late time behavior of the probability distribution for an observer to measure a given value of the cosmological constant. We find the diffusion of the probability distribution to significantly slow down in sectors of the landscape where the number of nearest neighboring vacua ...

Energy Technology Data Exchange (ETDEWEB)

The use of vacuum multifoil (VMF) container for thermal insulation in long-life thermal batteries was investigated in a proof-of-concept demonstration. An InvenTek-designed VMF container 4.9 inches in diameter by 10 inches long was used with an internally heated aluminum block, to simulate a thermal-battery stack. The block was heated to 525 C or 600 C and allowed to cool while monitoring the temperature of the block and the external case at three locations with time. The data indicate that it should be possible to build an equivalent-sized thermal battery that should last up to six hours, which would meet the requirements for a long-life sonobuoy application.

International Nuclear Information System (INIS)

We investigate the quantum cosmology of spatially homogeneous models with compact spatial sections admitting a u(2) isometry algebra. The metric ansatz in these models is that of Bianchi type IX with two scale factors set to be equal. We apply the Hartle-Hawking no-boundary path integral prescription and find the semi-classical contributions to the wave function. Exact formulae are obtainable for certain contributions and otherwise the limits of large and small anisotropy (for the pure vacuum case) and large spatial volume or small anisotropy (for the case with a positive cosmological constant) are considered. For the pure vacuum case we find no semiclassical components which would correspond to Lorentzian universes. For the case with a cosmological constant the Hartle-Hawking boundary conditions formally constrain one of the parameters in the Lorentzian solutions to be purely imaginary. Possible interpretations of this imaginary parameter are ...

British Library Electronic Table of Contents (United Kingdom)

The design and operating principle of a small (50 mm in diameter and 100 mm in height) ???-73C vacuum spark gap are described. It is shown that it can be efficiently switched using a control circuit with a low (?900 V) supply voltage, which is based on an inductive energy storage and a diode opening switch that forms a high-voltage igniting pulse with a rise time of nanosecond duration. The ???-73C switching process is investigated at different rise times of igniting voltage pulses and different igniting current amplitudes. The results of tests of the spark gap operating in regimes of switching current pulses with an amplitude of 12 kA and a rise time of 800 ns are presented.

CERN Document Server

We have developed a liquid jet injector system that can be used for hydrated sample delivery at X-ray Free Electron Laser (XFEL) sources and 3rd generation synchrotron sources. The injector is based on the Gas Dynamic Virtual Nozzle (GDVN), which generates a liquid jet with diameter ranging from 300 nm to 20 {\\mu}m without the clogging problems associated with conventional Rayleigh jets. An improved nozzle design is presented here. A differential pumping system protects the vacuum chamber and an in-vacuum microscope allows observation of the liquid jet for diagnostics while it is being exposed to the X-ray beam. A fiber optically coupled pump laser illuminating the jet is incorporated for pump-probe experiments. First results with this injector system have been obtained at the LCLS.

Energy Technology Data Exchange (ETDEWEB)

The authors calculate the effective potential for the bosonic sector of eleven-dimensional supergravity on the background (Minkowski) x (sphere). No tachyons are found, and it is shown that the antisymmetric tensor field does not threaten graviton dominance when the Freund-Rubin parameter (m) vanishes. The general case (m not = O) seems untractable in the present formalism.

Energy Technology Data Exchange (ETDEWEB)

A Bianchi type-IX cosmological model has been found as a solution of Einstien's vacuum field equations with a cosmological constant. The solution represents a rotating generalziation fo the de Sitter universe. This universe shows a transition to exponential expansion and the vorticity begins to decay exponentially at the grand-unified-theory time. The point of time for this transition is independent of the magnitude of the vorticity. During the Guth inflationary era the vorticity decays by a factor of the order 10 US.

International Nuclear Information System (INIS)

This paper extends the development of a new formulation of the theory of tachyons to encompass the dynamics of tachyons. Energy and momentum are discussed along with the proper mass of a tachyon. The transformation of force in extended relativity (ER) is derived. Acceleration in ER is also discussed, as well as the relationship between force and acceleration. Two simple examples relating to the motion of a charged tachyon are discussed, followed by a brief explanation of why tachyons cannot emit Cerenkov radiation in a vacuum. 13 refs., 3 figs.

Energy Technology Data Exchange (ETDEWEB)

The motion of an accelerated charge in a vacuum is analyzed, via the superposition principle and Fourier analysis, into uniform-motion components, which include bradyonic as well as tachyonic contributions. It is shown that the former contribute only to the induction fields whereas the latter are the source of the radiation emitted by the charge, via the Sommerfeld-Cerenkov mechanism. This result calls for a reexamination of some recently formulated theories of superluminal particles.

Energy Technology Data Exchange (ETDEWEB)

A Monte Carlo simulation of the vacuum Bianchi type-IX (mixmaster) cosmology yields a significant correlation between large universe volume and high anisotropy. An analog of the model's chaotic classical behavior is seen in the break up of the universe wave function at large volume into fingers in the corners of the minisuperspace anisotropy potential.

Energy Technology Data Exchange (ETDEWEB)

To suppress space charge blowup in an ion beam passing through a photoneutralizer, it is necessary to introduce some background gas. An analysis is presented of the neutralization of a high-energy, >200-keV negative deuterium ion beam, exposed to photodetachment while in the presence of deuterium. With a gas thickness of <0.01 Torr.cm, the neutral fraction in the output beam is found to be about the same as that gotten from the photoneutralizer operating in vacuum. Neutral atom beam injection for plasma heating is discussed.

Energy Technology Data Exchange (ETDEWEB)

An F-theory dual of a non-supersymmetric orientifold is considered. It is argued that the condensation of both open and closed string tachyons in the orientifold corresponds to the annihilation of branes and antibranes in the F-theory dual. One likely end-point of tachyon condensation is thus expected to be the vacuum of Type-IIB superstring. Some speculations are presented about the F-theory dual of the bosonic string and tachyon condensation thereof.

International Nuclear Information System (INIS)

A new external-PIXE system utilizing a differential pumping technique, which can completely protect the accelerator and vacuum pumps when the exit foil breaks down, has been developed. Applications to analyses of liquid and heavily-outgassing samples were successfully achieved. Also, experiments for evaluating the efficiency of the system were performed and results will be presented. (author)

Wastenet

... The products can be categorised as glazed flat-plate collectors, evacuated glass-tube collectors, and unglazed plastic or low temperature collectors. Glazed flat-plate collectors and vacuum tubes are widely used for solar water heating and space heating systems in all types of buildings. Unglazed plastic collectors are used exclusively for lower temperature applications, such as outdoor swimming pools or the agrarian business. Flat-plate solar collectors are likely to ...

Energy Technology Data Exchange (ETDEWEB)

In-situ air stripping employs horizontal wells to inject or sparge air into the ground water and vacuum extract VOC`S from vadose zone soils. The horizontal wells provide better access to the subsurface contamination, and the air sparging eliminates the need for surface ground water treatment systems and treats the subsurface in-situ. A full-scale demonstration was conducted at the Savannah River Plant in an area polluted with trichloroethylene and tetrachloroethylene. Results are described.

Energy Technology Data Exchange (ETDEWEB)

A prototype of a muffin-tin accelerating structure operating at 32 times the SLAC frequency (2.856 GHz) was built for research in high gradient acceleration. A traveling-wave design with single input and output feeds was chosen for the prototype which was fabricated by wire electrodischarge machining. Features of the mechanical design for the prototype are described. Design improvements are presented including considerations of cooling and vacuum.

CERN Document Server

Canonical gravity in real Ashtekar-Barbero variables is generalized to allow for fermionic matter. The resulting torsion changes several expressions in Holst's original vacuum analysis, which are explicitly displayed here. This in turn requires adaptations to the known canonical (loop) quantization of gravity coupled to fermions, which is discussed on the basis of the classical analysis.

CERN Document Server

Here we show that self-propulsion in quantum vacuum may be achieved by rotating or aggregating magneto-electric nano-particles. The back-action follows from changes in momentum of electro-magnetic zero-point fluctuations, generated in magneto-electric materials. This effect may provide new tools for investigation of the quantum nature of our world. It might also serve in the future as a "quantum wheel" to correct satellite orientation in space.

British Library Electronic Table of Contents (United Kingdom)

Abstract Thermomechanical behavior of membranes based on blends of poly(vinyl alcohol) (PVA) with different weight percentage (wt %) of glycerol has been studied. Solid-state PVA/Glycerol polymer membranes were prepared by a solution casting method. The films were studied for thermal characteristics by differential scanning calorimetry (DSC) and thermogravimetric analysis and for the mechanical properties including hardness and modulus by nanoindentation method. The dispersion of glycerol within the polymer matrix was examined using scanning electron microscopy. Fourier transform infrared spectroscopy was used to confirm the formation of hydrogen bonding between the plasticizer and PVA in their blends and also to provide information on compatibility and physical interactions between the gl...

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Fatigue tests were accomplished with a series of specimens doped with trace elements of a hardened Fe-Ni-Cr alloy, cast and hardened with intermetallic phases for determining the influence of these elements on the high temperature strength properties. The results of extensive fatigue tests show that even small contents of Te, Bi, Se, Pb, Tl and Zn considerably influence the life and creep processes especially after longer running periods, when added individually or combinedly. In contrast to this, the fatigue ductility is reduced by trace element additions even with short running periods. The order in which the metallic trace elements influence the fatigue properties nearly correlates with earlier work concerning Ni- and Co-superalloys. (orig.)

Energy Technology Data Exchange (ETDEWEB)

A method of abrasion testing according to ASTM C 704-76 a is presented for steel fibre concrete mortar, fusion-cast basalt and a surface coating material and results of practical interest are mentioned. Due to the high technical demands on these materials and their specific fields of application, the very first test already supplied interesting findings. From the user's point of view, the method is an interesting alternative to the common test methods, e.g. according to DIN 52 108 (wheel test according to Boehme). In English-speaking countries, testing according to ASTM is often mandatory in the refractory industry in order to assure constant quality of refractory materials after setting. The method is characterized by good comparability and high accuracy of measurement. Only the test piece is exchanged while the test conditions remain constant, so that accurate information on the material studied is obtained.

International Nuclear Information System (INIS)

The whole equipment consists of three separate portable parts: a detector case, a microprocessor and a graphic TV monitor. Magnetic tape memory and an x-y recorder can be connected for recording the measured spectra. The analyzer contains two built-in exchangeable excitation radionuclides. Fluorescence and scattered radiation is detected using a proportional detector. The detected pulses are analyzed by a 256-channel analyzer and the results are shown on the display. The device may be used in mining laboratories, coal and ore dressing plant control rooms or in mining fields of open cast mines for quick detection of the quality of mined or dressed raw materials. (E.S.). 1 fig.

Energy Technology Data Exchange (ETDEWEB)

This report describes all time and frequency analysis parameters measured with the new Nuclear Weapons Identification System (NWIS) processor with three input channels: (1) the {sup 252}Cf source ionization chamber; (2) a detection channel; and (3) a second detection channel for active measurements. An intuitive and physical description of the various functions is given as well as a brief mathematical description and a brief description of how the data are acquired. If the full five channel capability is used, the number of functions increases in number but not in type. The parameters provided by this new NWIS processor can be divided into two general classes: time analysis signatures including multiplicities and frequency analysis signatures. Data from measurements with an 18.75 kg highly enriched uranium (93.2 wt%, {sup 235}U) metal casting for storage are presented to illustrate the various time and frequency analysis parameters.

Energy Technology Data Exchange (ETDEWEB)

Because power requirements in induction heating applications are largely dependent on the physical properties of the product to be heated, inducting, heating is mainly used in steelwork applications, for the manufacture of finished or semi-finished parts. Applications here cover five main types of steelworks operation: smelting, heating prior to forming, heat treatment, surface treatment, and assembly process. At the same time, technological progress has opened up innovative applications in sectors such as chemical and agro-food industries. Other emerging applications for induction include direct forming of liquid metal, wholly or partially replacing mechanical transformations on solid metal. Techniques include electromagnetic forming, continuous cold-crucible casting, electromagnetic mixing, flow control by continuous magnetic field, and production of intense sliding fields (pumps, flow regulation). (author)

British Library Electronic Table of Contents (United Kingdom)

High molecular weight samples of the novel biodegradable polyester poly(ethylene sebacate) (PESeb) were synthesized. Miscible poly(ethylene sebacate)/poly(4-vinyl phenol) semicrystalline/amorphous blends were prepared by applying the solvent casting method. Miscibility was proved by the single composition dependent glass transition temperature over the entire composition range observed in DSC traces of the quenched blend samples and also by the melting point depression. The Flory-Huggins interaction parameter was found to be x12 = -1.3. Also, FTIR spectra supported the hypothesis of intermolecular interactions due to hydrogen bonding. The crystallization of PESeb in blends was studied. As expected, isothermal crystallization rates decreased in the blends with increasing the PVPh content. T...

British Library Electronic Table of Contents (United Kingdom)

Abstract Within the framework of the CRC 799 -TRIP-Matrix-Composites- at the TU Bergakademie Freiberg new composite materials consisting of TRIP steel and zirconium dioxide ceramics are designed in a powder route and a casting route. To manufacture faultless samples basic investigations of the feeding and infiltration behaviour within macro porous ceramics such as filters were needed. The effects of bottom pouring and top pouring were investigated as well as the effects of different preheating temperatures, contents of phosphorous in the steel and flow trough rates. Bottom pouring corrupts the feeding mainly of filters with high ppi (pores per inch). Top pouring improves the feeding, but generates inhomogeneous infiltration qualities, which can affected and enhanced by a increasing preheat...

Energy Technology Data Exchange (ETDEWEB)

The present conference discusses plasma-assisted surface coating/modification processes, the applications to date of ion nitriding, the effects of nitrogen on metal surfaces, ion nitriding mechanisms in Cr, Al and Cr + Al-containing 1040 steel, ion nitriding of Al and its alloys, life enhancement for forging dies, novel anode plasma nitriding developments, and a comparative study of the pulsed and dc ion-nitriding behavior in specimens with blind holes. Also discussed are the influence of heating method on ion nitriding, surface hardening of marage steels by ion nitriding without core hardness reduction, plasma nitriding of nodular cast iron sput gears, NbN composites for superconductors, the carburization of tungsten in a glow discharge methane plasma, economic considerations concerning plasma nitriding, and the corrosion properties obtained by ion nitriding.

Energy Technology Data Exchange (ETDEWEB)

Fuji Electric has realized highly reliable and functional control systems by the dispersion type control system FOCUS, which uses the controller (ICS-2000) enjoying good reputation in controlling industrial plants for a long time and a personal computer with high windows operability, the former for controlling and the latter for MHI responsible for monitoring. The smelting process in a steel-making plant needs a highly reliable system for advanced control to ensure continuous operation. Fuji Electric delivered the FOCUS system to Kubota in 1998, as the smelting furnace instrumentation/control system for the cupola furnace. The system has been in service smoothly. Moreover, a total of four control systems have been delivered, 2 for steel-making furnaces and the other 2 for continuous casting. (NEDO)

Energy Technology Data Exchange (ETDEWEB)

Super light and high performance Mg{sub 2}Si/Mg composites, which had excellent mechanical properties, were developed via the combination of solid-state synthesis and hot extrusion process. In this study, cold compacting (CP) and repeated plastic working (RPW) were firstly carried out for the mixture of Mg-Si powders, and the refinement of both Mg grains and dispersoids. Each specimen was evaluated by observation of microstructure and tensile test. As a result, it was understood that Mg{sub 2}Si dispersoids were refined and dispersed into Mg matrix, and were flowed along extrusion direction. And their mechanical properties were higher than the conventional die casting alloys. Also the effect of RPW as the improvement of properties and the decrease of synthesis temperature were confirmed. (orig.)

Energy Technology Data Exchange (ETDEWEB)

In this book over 250 alloys are organized by AISI number into 10 major sections: Irons, Carbon Steels, Alloy Steels, Low Alloy Constructional Steels, Ultra High Strength Steels, Tool Steels, Maraging Steels, Wrought Stainless Steels, Heat Resistnat Casting Alloys, and Iron Based Rought Superalloys. Each alloy record lists the designation, specifications, UNS number, composition, product forms and a comment on the high-temperature properties and applications. Referenced data is then given for physical properties such as density, specific heat, thermal conductivity, thermal expansion, electrical conductivity, Poisson's ratio, moduli of elasticity and rigidity, etc. Mechanical properties follow, and include tensile properties, shearing and bearing properties, impact properties, creep, stress rupture and stress relaxation and fatigue properties. The last part of the alloy record gives other effects of temperature, such as hot hardness, corrosion, and growth.

British Library Electronic Table of Contents (United Kingdom)

The effects of a modifier that contains Rare Earths (RE), low melting point alloy (Al-Bi-Sb) and Ca-Si alloy on an ultrahigh carbon steel containing 1.9wt.% C were studied. Microstructure characterization was carried out with optical microscopy (OM) and scanning electronic microscopy (SEM) combined with energy-dispersive spectrometry (EDS). Upon modification, the continuous eutectic carbide network structure was broken up and changed to a partly isolated and finer blocky structure in the as-cast alloy. Differential scanning calorimetry (DSC) revealed that the eutectoid temperature increased and the eutectic temperature decreased for the modified alloy. Modification also improved the impact toughness of the tempered steel, with a significant increase from 6.5 to 12.6Jcm^-^2, despite the har...

Energy Technology Data Exchange (ETDEWEB)

Problems can sometimes occur during the construction of cast in-situ concrete piles. These foundations are formed by drilling a substantial hole into the ground and subsequently filling it with steel reinforcement and wet concrete. Several well-documented cases exist where concrete has not filled the hole and substantial voids have been left in the apparently completed pile. A theory has been developed by which it is possible to identify the nature, size and position of a finite defect within a suspect pile. The technique is based on the concept of receptances, and requires information obtained from vibration tests performed on piles after the concrete has hardened, and the nominal dimensions and material properties of the pile. The application of the theory is demonstrated using data relating to a pile with a known defect. The theory described in this paper ignores the effect of the surrounding soil; this can be included by further development of the theory.

British Library Electronic Table of Contents (United Kingdom)

ABSTRACT Purpose: There is a consensus in the community of dental research that the selection of undersized artificial maxillary anterior teeth offers an unnatural appearance to the denture. Several methods to select the adequate width of these teeth are of questionable validity, and many dentures have an obviously artificial appearance. This article assessed the relationship between the individual and the combined width of maxillary anterior teeth. Materials and Methods: Impressions were made of the anterior dentition of 69 dentate undergraduate students with rubber impression silicon, and casts were formed. The individual widths of the maxillary anterior teeth were measured by using a digital caliper (SC-6 digital caliper, Mitutoyo Corporation, Tokyo, Japan), and the combined width was r...

British Library Electronic Table of Contents (United Kingdom)

Statement of problem Even though metal ceramic restorations (MCRs) are widely used by clinicians, the influence of the metal on the color of overlaying porcelain is unknown. Purpose The purpose of this study was to analyze the color alterations of different types of metal ceramic alloys during several stages of metal surface preparation and to determine the effect of those changes on the resulting color of opaque porcelain (OP). Material and Methods Seven different types of alloys (3 base metal, 3 noble, and 1 high noble) were used to prepare disk-shaped specimens (1 mm x 10 mm, n=3), followed by OP application (0.1 mm). Lab values of specimens were recorded after different stages of metal surface preparation (ingot, after casting, after oxidation, and after the OP application) in addition...

Energy Technology Data Exchange (ETDEWEB)

A combination of erosion and corrosion at the Victoria Junction coal preparation plant in Sydney, Nova Scotia was causing serious problems. Schedule 80 mild steel pipes were starting to fail as well as some quarter-inch steel plates in the lauders and chutes. Some corrosion tests were carried out and the high chloride level in the process water was felt to be the single most important contribution to the corrosion problem. Cast basalt was selected as a solution to the pipe wear problem. Three different types of abrasion/corrosion-resistant tiling - basalt tiles, kalceram tiles and ceramic tiles were well suited to the chloride conditions at this plant.

Science.gov (United States)

The content of the courseware for this CD-ROM on Foundry Operations is designed to teach college engineering students and practicing engineers the conepts of foundry operations involving: mold-making, charging of blast furnace and cupola furnace, metal melting, pouring of molten metal into mold to make castings, and computation of mold-metal interface forces. There is an interactivity between students and this instructional program through animation and robot application. Students are able to input data into the software and get a response. For an example, if wrong data are put into calculating the mold-metal interface forces, the molten metal will run over the mold, showing a negative response. Messages will flag and will indicate what to do to correct the situation.

British Library Electronic Table of Contents (United Kingdom)

A superhydrophobic SiO2/nylon 6,6 nanocomposite coating was fabricated by a facile casting process. Compared with the intrinsically hydrophilic pure nylon 6,6, the as-prepared coating displayed a superhydrophobic property in the pH range from 1 to 14. It was also found that the resulting water contact angles of the as-prepared surface were always larger than 159?, but the sliding angles had an obvious decrease from about 33.4??1? as the content of SiO2 nanoparticles increased. In addition, a transition from the transitional superhydrophobic state between Wenzel?s and Cassie?s state to the Cassie?s state was observed.

Energy Technology Data Exchange (ETDEWEB)

Exploratory experiments of laser welding cast Ni-based superalloy K418 turbo disk and alloy steel 42CrMo shaft were conducted. Microstructure of the welded seam was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectrometer (EDS). Mechanical properties of the welded seam were evaluated by microhardness and tensile strength testing. The corresponding mechanisms were discussed in detail. Results showed that the laser-welded seam had non-equilibrium solidified microstructures consisting of FeCr{sub 0.29}Ni{sub 0.16}C{sub 0.06} austenite solid solution dendrites as the dominant and some fine and dispersed Ni{sub 3}Al {gamma}' phase and Laves particles as well as little amount of MC short stick or particle-like carbides distributed in the interdendritic regions. The average microhardness of the welded seam was relatively uniform and lower than that of the base metal due to partial ...

Energy Technology Data Exchange (ETDEWEB)

Crankshafts of the pearlitic-sorbitic nodular cast iron type JUS NL.80 (similar to DIN GGG-80) heat treated to get a tensile strength of 820-900 GPa (i.e. a Vickers hardness of 268-295 HV) were plasma and ammonia gas nitrided. The glow discharge plasma nitriding was performed for 20 h at about 500degC in a gas mixture of 55% N{sub 2} and 45% H{sub 2}. The gas nitriding was performed for 28 h at 510degC in the ammonia gas. Evaluation of the nitrided surfaces was conducted by optical microscopy, X-ray diffractometry and microhardness measurements. Journal and crank pin dimensions and surface roughness were measured both before and after nitriding. Bending fatigue testing of crankshafts was performed using a fatigue testing rig. The fatigue limit was evaluated at 5.0x10{sup 6} cycles. The fractures happened at the transition radius of the journal with cracks starting beneath the nitrided layer. It was found that the nitrided crankshafts had 18% higher dynamical ...

Energy Technology Data Exchange (ETDEWEB)

The advent of light metal alloys and advanced materials (polymer, composites, etc.) have brought the possibility of achieving important energy reductions into the full life cycle of these materials, especially in transportation applications. 1 These materials have gained acceptance in the aerospace industry but use of light metal alloys needs to gain wider acceptance in other commercial transportation areas. Among the main reasons for the relatively low use of these materials are the lack of manufacturability, insufficient mechanical properties, and increased material costs due to processing inefficiencies. Considering the enormous potential energy savings associated with the use of light metal alloys and advanced materials in transportation, there is a need to identify R&D opportunities in the fields of materials fabrication and forming aimed at developing materials with high specific mechanical properties combined with energy efficient processes and good manufacturability. ...

International Nuclear Information System (INIS)

Coiling or infusion of embolic materials into a wide necked aneurysm can be performed with stenting. The purpose of our study is to assess the technical feasibility of aneurysm treatment with glue embolization after stenting. We used four Wallstents for surgically repairing eight canine carotid aneurysms. After confirmation of the aneurysms on the angiogram, we introduced a 6-7 F guiding catheter in order to deploy the stents. After stenting, we passed a microcatheter into the aneurysm lumen through the stent mesh. 28% glue was slowly injected until the glue cast completely filled the lumen. We evaluated the passage of a microcatheter through the stent meshwork, formation of the glue cast and the stents' ability to protection for any leakage of glue. The follow-up angiogram was obtained for two dogs, one to three times until 8 weeks, and then we sacrificed the dogs and performed pathologic examinations. Stenting was successful in all cases ...

International Nuclear Information System (INIS)

The physical, chemical and mechanical properties of magnesium alloys make them attractive materials for automotive and aerospace applications. However, these materials are susceptible to corrosion and wear. This work discusses the potential of using sol-gel based coatings consisting of ZrO_2 and 15 wt.% of CeO_2. The CeO_2 component provides enhanced corrosion protection, while ZrO_2 impart corrosion as well as wear resistance. Coating deposition was performed by the dip coating technique on two magnesium alloy substrates with different surface finishes: AZ91D (as-casted, sand-blasted, and machined) and AZ31 (rolled and machined). All as-deposited coatings (xerogel coatings) were then subjected to 10 h annealing: a temperature of 180 C was applied to the AZ91D alloy and 140 C to the AZ31 alloy. Morphological and structural properties of the annealed coatings were investigated by scanning electron microscopy, atomic force microscopy and transmission electron ...

Energy Technology Data Exchange (ETDEWEB)

To study the fatigue life of extruded AZ31 (3%Al, 1%Zn, 0.3%Mn, Mg - the rest), AM50 (5%Al, 0.4%Mn, Mg - the rest) and ZK60 (5%Zn, 0.5%Zr, Mg - the rest) Mg alloys in air and NaCl-based solutions, corrosion fatigue tests were carried out using a rotating beam type fatigue machine. For the analysis of the corrosion fatigue behavior of Mg alloys in different environments, fitted N{sub sol}/N{sub air} ratio considered as a relative corrosion fatigue life is used. Here N{sub sol} and N{sub air} are the numbers of cycles to failure in the solution and in air, respectively. An extruded ZK60 alloy shows very high fatigue and corrosion fatigue properties in comparison with other alloys. However, ZK60 shows the lowest values of the relative fatigue life (N{sub sol}/N{sub air} {proportional_to}10{sup -3}-10{sup -2}) compared to that for AM50 and AZ31 alloys (N{sub sol}/N{sub air} {proportional_to}10{sup -2} - 10{sup -1}). Generally, extruded alloys in comparison to earlier studied ...

Energy Technology Data Exchange (ETDEWEB)

The research supported by this Department of Energy contract has primarily been devoted to the study of the electronic properties of surfaces with sub-micron size. In previous years, we have studied the photoexcitation of electrons from field emission tips by a focussed Argon-ion laser beam tuned to operate at specific photon energy. The photoexcited electrons escape into the vacuum by tunneling through a surface potential barrier which is distorted by the application of a strong electric field. The interest in these experiments lies in a better understanding of the photoexcitation process at low photon energies. The techniques that have been developed directly measure the excited state energy distribution of electrons emitted through the surface potential barrier. The basic information gained from this research is relevant to opto-electronic devices which rely on photoexcitation of electrons in the presence of strong interfacial electric fields for their ...

Energy Technology Data Exchange (ETDEWEB)

The sequential layer-by-layer adsorption of polyanions and polycations to build polyelectrolyte multilayers has triggered enormous interest in their potential uses in a wide range of fields, from photonic to pharmaceutical applications. We show that the conformation of the solvent swollen films - prior to drying - is determined by the initial adsorption conditions, but can be altered ex-situ by exposure to a liquid phase of very high ionic strength. Recently it has been observed that the swelling depends on the charge of the outermost layer. In the PAH/PSS system we saw that assemblies with PSS as the outermost layer swell more than those with PAH outside. A neutron reflectivity study of this effect in addition indicated the existence of two kinds of water, bound with different strength within the films. Beside an unexpected two-step kinetics of swelling, the reflectivity curves of the layers against vacuum before and after re-hydration in D{sub 2}O vapor did not ...

International Nuclear Information System (INIS)

The reactive evaporation process was successfully used to deposit films of the A-15 Nb_3Ge phase. This is the first report, to the best of our knowledge, illustrating the use of such processes for the deposition of A-15 compounds. In this process, niobium vapors from an electron-beam-heated evaporation source react with germane gas introduced into the vacuum chamber at low partial pressures (approximately 10"-"4 Torr) to produce Nb_3Ge deposits. The process variables studied were the deposition temperature, the niobium-to-germanium impingement ratio on the substrate and the plasma-enhanced deposition, in this case the activated reactive evaporation process. At low deposition temperatures (below 450"0C) the deposit is amorphous (or microcrystalline) and can be crystallized to the Nb_3Ge phase by heat treatment, e.g. at 850"0C for 1 h in vacuum. The ratio of niobium to germanium in the deposit can be varied by changing the process parameters. The ...

Energy Technology Data Exchange (ETDEWEB)

A computer model of cryogenic system for storing solid antimatter is used to explore the radiative cooling-power requirements for long-term antimatter storage. If vacuum-chamber pressures as low as 10 to -18th power torr can be reached, and the rest of the large set of assumptions is valid, milligram quantities of solid antimatter could be stored indefinitely at 1.5 K using cooling powers of less than a microwatt. Many of the assumptions made are problematic and need verification, as they could potentially change the results greatly. The system modeled is a sphere of solid anti-parahydrogen at 1.5 K or below levitated in a spherical cryogenic vacuum chamber. The free matter gas in the chamber is assumed to be molecular hydrogen, and sublimation of both matter and antimatter is assumed to be negligible. The antihydrogen is assumed to be in thermal equilibrium, although annihilation-energy deposition is localized and hydrogen's ...

International Nuclear Information System (INIS)

Measurements of the Kapitza conductance to liquid helium II across the (100) surface of single crystals of copper are presented. The temperature range of these measurements was 1.6-- 2.1 K. The sample surfaces were subjected to several different treatments. Some surfaces were cleaned by low-energy argon ion bombardment, annealed in an ultrahigh-vacuum system, and preserved under vacuum until purified liquid helium was admitted. Other surfaces were intentionally damaged by machining and/or exposure to the atmosphere. The conductance after these latter treatments was found to be about a factor of three higher than that of the more ideally cleaned and annealed surfaces, and a significant difference in the temperature dependence of the conductance was also observed. Conductances were reproducible for similarly treated surfaces and correlated with surface damage determined by x-ray diffraction. The relationship of these results to the numerous ...

Energy Technology Data Exchange (ETDEWEB)

Pd was deposited onto Si (111) 7x7 surface at approximately 700 K inside an ultrahigh vacuum transmission electron microscope. Plan-viewed transmission electron microscopy (TEM) observation indicated that the islands have two kinds of shapes, round and rectangular (one-dimensional) ones. In a diffraction pattern for the rectangular islands, extra spots along the <110> direction of the Si surface, spacing of which is 1/8 times as long as that of Si (220) spots, were seen. A high resolution TEM image showed the corresponding superstructure in the rectangular islands. In situ observation of the growing process of the rectangular islands showed repeat of introduction and relief of strains during the growth, suggesting that such superstructure would be constructed by stacking compositionally different phases or introducing defects so that the periodically maximized strain is relieved.

International Nuclear Information System (INIS)

The quantum behavior of the vacuum Bianchi type-IX universe with the cosmological constant is investigated in terms of the Ashtekar variables. An exact solution to the quantum Hamiltonian constraint in the holomorphic representation is given. This solution reduces to the Hartle-Hawking wave function in the spatially isotropic sector and extends in the triad representation to the classically forbidden region where the determinant of the spatial metric becomes negative. The analysis of the quantum Robertson-Walker universe indicates that if the superspace is extended to such a classically forbidden region, the holomorphic representation picks up some restricted class of solutions in general. This observation leads to a new ansatz on the boundary condition of the Universe. In particular, the behavior of the Lorentzian and Euclidean WKB orbits corresponding to the solution suggests a new picture on the semiclassical behavior of the quantum Universe: that the Universe ...

International Nuclear Information System (INIS)

The principle and history of free-electron laser (FEL), first evidenced in 1977, the relationship between FEL wavelength and output power, the high-power FEL driven by the superconducting linac, the X-ray FEL by the linac, and the medical use are described. FEL is the vacuum oscillator tube and essentially composed from the high-energy linac, undulator and light-resonator. It utilizes free electrons in the vacuum to generate the beam with wavelength ranging from microwave to gamma ray. The first high-power FEL developed in Japanese Atomic Energy Research Institute (JAERI) is based on the development of superconducting linac for oscillating the highest power beam. In the medical field, applications to excise brain tumors (in US) and to reconstruct experimentally blood vessels in the pig heart (in Gunma University) by lasing and laser coagulator are in progress with examinations to remove intra-vascular cholesterol mass by irradiation of 5.7#mu#m ...

International Nuclear Information System (INIS)

The current--density profile of a focused ion beam (FIB) has a central peak accompanied by broader ''wings'' that, while unimportant in lithographic applications, can lead to unwanted effects during an implantation operation. The origin of the wings, and hence the best way to minimize them, is not clear and needs further study. We have measured the line profiles of several of the ions available in our FIB machine as a function of a number of variables, under ultrahigh vacuum (UHV) conditions. No effects are observed from changes in emission current or deliberate defocusing of the objective lens. There are some changes with beam aperture and/or current, but the biggest differences seem to be associated with a change of source type and hence, possibly, with a change in the source/extractor configuration or in the alloy and the emission process. The wing amplitudes are appreciably lower than many previously observed, and their profiles, at least for the lighter ions ...

International Nuclear Information System (INIS)

Ceramic matrix composites in the TiC-Ti, Y-TZP system can be synthesized by the reaction between carbon and the TiO_2-Y_2O_3-ZrO_2 solid solution nanopowder. This method results in the more homogeneous powders than those prepared by the physical mixing of TiC and zirconia s.s. powders. Twelve TiO_2-Y_2O_3-ZrO_2 solid solution nanopowders differing in the proportions of the constituent oxides were prepared by the coprecipitation- calcination route. They were reacted with the pyrolytic carbon evenly distributed within the system. Carbon was introduced by the thermal decomposition of the phenol-formaldehyde resin dissolved in ethyl alcohol and mixed with the zirconia s.s. nanopowder. Reaction was performed in vacuum. Compacts of the composite powders sintered in vacuum give dense materials of evenly distributed TiC inclusions of sizes not surpassing 400 nm. Hardness of such materials was dependent on their chemical and phase composition but was ...

International Nuclear Information System (INIS)

We investigate the quantum cosmology of spatially homogeneous models with compact spatial sections admitting a u(2) isometry algebra. The metric ansatz in these models is that of Bianchi type IX with two scale factors set to be equal. We apply the Hartle-Hawking no-boundary path integral prescription and find the semi-classical contributions to the wave function. Exact formulae are obtainable for certain contributions and otherwise the limits of large and small anisotropy (for the pure vacuum case) and large spatial volume or small anisotropy (for the case with a positive cosmological constant) are considered. For the pure vacuum case we find no rapidly oscillating semiclassical components in the wave function, and hence do not recover lorentzian space-time as a prediction of the no-boundary proposal. For the case with a cosmological constant the wave function does contain rapidly oscillating components and thus predicts approximately ...

International Nuclear Information System (INIS)

The structure of a demountable vacuum joint designed for operation from -120 to +120 deg C is developed and tested. Requirements of especially low gas release from the materials used have been fulfilled; the same concerns low sealing efforts, repeated action and keeping tightness under loads, indium being used as a sealant. Experimental studies of demountable vacuum joints, dia 100,125,140,160,180 and 200 mm, with an indium sealant permit to make the following conclusions: 1. The joints are sealed at sealing specific efforts of 0.4 kg/mm (without considering atmospheric pressure). 2. The joints retain tightness at opening and closing a cover five times and under +-120 deg C. 3. To ensure repeated operation of the joint with continued stable sealing effort, one should make sure the sealed surfaces coincide at repeated sealing. 4. When operating demountable vaccum joints with indium sealant, one must take into account the time factor, since time ...

Energy Technology Data Exchange (ETDEWEB)

A nuclear battery based on the direct energy conversion of the fission products is presented. Such energy conversion is possible by using a nuclear reactor with ultra-thin fuel elements of 0.2 {mu}m of {sup 242m}Am. The amount of nuclear fuel is 376 g and the dimensions of the battery are 2.4x2.4x2.4 m{sup 3} (including the vacuum spacing), with a BeO moderator and Be electrodes. The total power of the reactor is 10.6 MW and the electrical power is 0.652 MW.

Energy Technology Data Exchange (ETDEWEB)

This paper reports on the results of experiments into efficient higher-order anti-Stokes Raman conversion of tunable short-pulse XeCl laser radiation. The maximum output energy of the pumping laser, in which the radiation of a frequency-doubled dye laser is amplified by two XeCl laser amplifiers, is 55 mJ with a pulse duration of 1 ns FWHM. Using hydrogen gas as a Raman medium, a series of anti-Stokes lines up to the 12th order (121.5 nm) is generated in the vacuum ultraviolet (VUV) region. 16 references.

Science.gov (United States)

A nitrogen liquefier and computer controlled valving system have been added to the Bevatron cryoliner vacuum system to cut operating costs by reducing liquid nitrogen consumption. The computer and interface electronic systems, which control the temperatures of twenty-eight liquid nitrogen circuits, have been chosen and designed to operate in the Bevatron's pulsating magnetic field. The nitrogen exhaust is routed back to a liquefier, of about five kilowatt capacity, liquefied, and rerouted through the cooling circuits. A description of the system and operating results are presented.

British Library Electronic Table of Contents (United Kingdom)

Methods of X-ray diffraction and transmission electron microscopy were used to study the microstructure of dispersion-strengthened Cu-Al2O3 nanocomposites obtained by the method of simultaneous deposition of Cu and Al2O3 from the vapor phase. The effect of the size of particles of the oxide (Al2O3) and of their content on the electrical resistance of the composite has been considered. The results obtained make it possible to suppose that the main structural factor that determines the electrical resistance of the composite are nanodispersed particles of Al2O3 with a size of less than 20 nm.

CERN Document Server

We study quantum Darwinism -- the redundant recording of information about a decohering system by its environment -- in zero-temperature quantum Brownian motion. An initially nonlocal quantum state leaves a record whose redundancy increases rapidly with its spatial extent. Significant delocalization (e.g., a Schroedinger's Cat state) causes high redundancy: many observers can measure the system's position without perturbing it. This explains the objective (i.e. classical) existence of einselected, decoherence-resistant pointer states of macroscopic objects.

International Nuclear Information System (INIS)

We construct a phenomenological model which describes the dynamical chiral symmetry breaking (DCSB) of a QCD vacuum and reproduces meson spectra. Quark condensates, the pion decay constant, and meson spectra are well reproduced by the phenomenological interaction which consists of a linear confining potential, a Coulombic potential, and the close-quote t Hooft determinant interaction. In this model, the close-quote t Hooft determinant interaction plays an important role to not only the mass difference between the #eta# and #eta#"' mesons, but other meson masses through DCSB. copyright 1997 The American Physical Society.

International Nuclear Information System (INIS)

In this study, Multi-Walled Carbon Nanotubes (MWCNTs) / Hydroxylapatite (HAp) composites were made to improve mechanical properties by using Spark Plasma Sintering (SPS) method. Slurry 6 mol of CaHPO4#centre dot#2H2O (DCPD), 4 mol calcium hydroxide and MWCNTs were mixed and sintered by using SPS at 5-120 MPa pressure, 1200-1250 deg. C and in vacuum or N2 atmosphere. The fracture toughness of sintered MWCNTs/HAp composites was increased.

International Nuclear Information System (INIS)

Within the APROS simulation environment we have built a thermo-hydraulic model of a conceptual fusion power plant which is water cooled and uses lithium-lead for tritium breeding. For the safety assessment of this design we have studied an accident sequence which starts from a loss or coolant flow then leads to first wall breach and pressurisation of the vacuum vessel. Simulations have revealed strong pressure transients which can be alleviated by design changes. One goal is to verify the adequacy of the containment design: it remains intact at least 14 h without any mitigating efforts. Estimates for radioactive releases are obtained. (author)

British Library Electronic Table of Contents (United Kingdom)

Abstract. The modification of kaon and antikaon properties in the interior of (proto-)neutron stars is investigated using a chiral SU(3) model. The parameters of the model are fitted to nuclear-matter saturation properties, baryon octet vacuum masses, hyperon optical potentials and low-energy kaon-nucleon scattering lengths. We study the kaon/antikaon medium modification and explore the possibility of antikaon condensation in (proto-)neutron star matter at zero as well as finite temperature/entropy and neutrino content. The effect of hyperons on kaon and antikaon optical potentials is also investigated at different stages of the neutron star evolution.

CERN Document Server

Contrary to some previous claims, we find a sizable instanton contribution to the finite energy sum rule used to extract the value of the strong coupling from the measured $\\tau$ decay widths. It is of the same order of magnitude as standard nonperturbative corrections induced by vacuum quark and gluon condensates. Our result indicates that there might be no hierarchy of power corrections in finite energy sum rules at the scale of $\\tau$ mass. Therefore, the standard nonperturbative corrections do not necessarily improve the accuracy of the theoretical predicition, but can rather be used to estimate an intrinsic accuracy of the pure perturbative calculation, which turns out to be rather high on this evidence, of order one percent.

Energy Technology Data Exchange (ETDEWEB)

In Situ Bioremediation (ISB) is the term used in this report for Gaseous Nutrient Injection for In Situ Bioremediation. This process (ISB) involves injection of air and nutrients (sparging and biostimulation) into the ground water and vacuum extraction to remove Volatile Organic Compounds (VOCs) from the vadose zone concomitant with biodegradation of the VOCs. This process is effective for remediation of soils and ground water contaminated with VOCs both above and below the water table. A full-scale demonstration of ISB was conducted as part of the Savannah River Integrated Demonstration: VOCs in Soils and Ground Water at Nonarid Sites. This demonstration was performed at the Savannah River Site from February 1992 to April 1993.

Energy Technology Data Exchange (ETDEWEB)

The two model MP Tandem Van de Graaff accelerators at Brookhaven have been used in a four-stage accel-decel configuration to produce highly stripped low energy heavy ions. The performance in this mode of operation has now been substantially improved by modifications of the second accelerator. The inclined field acceleration tube electrodes at the exit of this accelerator were replaced by straight electrodes, the vacuum was improved and the maximum negative terminal potential was increased. Higher intensity beams of heavier highly stripped ions can now be produced at lower energies than before.

CERN Document Server

A surface may provide a useful pumping action when able to retain adsorbed gas molecules for the duration of a given experiment. To fulfil this condition at room temperature, strong binding forces, as those resulting from chemical reactions, are required. Materials able to react with gases to form stable chemical compounds are called getters. The two main families of getters (evaporable and non-evaporable, or NEG) are presented and discussed. Special emphasis is placed on the NEG strips currently used for the vacuum systems of particle accelerators, and on the newly developed NEG thin-film coatings, in view of their possible future applications.

Energy Technology Data Exchange (ETDEWEB)

One of the most complicated tasks during the assembly of the Wendelstein W7-X is the installation of the superconductive coil system. The entire magnet system is enclosed between the Outer Vessel and the plasma vessel in high vacuum at 4 K. The coils are supported by a support structure, the Central Support Structure (CSS). The CSS carries all 70 coils, and it is designed as a closed ring made of 5 modules (10 half modules). The whole structure is supported by 10 Cryolegs which rest on the machine base. This paper describes the final design and manufacture of these Cryolegs.

International Nuclear Information System (INIS)

Purpose : To obtain an emergency core cooling device in a FBR type reactor by utilizing heat pipes which are not actuated at usual operation condition but actuated reliably upon emergency. Constitution : A system for injecting heat medium into heat pipes is provided. By injecting the heat medium into the heat pipes upon emergency to actuate the heat pipes, the reactor core is cooled. During normal reactor operation, the inside of the heat pipes is evacuated from a vacuum pump and no heat medium is filled therein, whereby unnecessary heat loss during the normal operation can be prevented. (Ikeda, J.).

International Nuclear Information System (INIS)

The nature of radicals in wood irradiated in vacuum was studied by ESR method. The decay rate of radicals changes in three temperature ranges. Long-lived radicals are very stable at 298"0K, at which the wood-plastics composite has often been studied. The number of radicals formed by irradiations shows fairly good agreement with the total number of radicals in each isolated wood component. The graft copolymerization of MMA to irradiated wood was also studied by means of ESR, and it was found that PMMA propagating radicals are formed in irradiated wood. These radicals are probably formed by the result of graft copolymerization of MMA of wood. (auth.).

Energy Technology Data Exchange (ETDEWEB)