International Nuclear Information System (INIS)
Kluson, J.; Jansky, B.
2009-01-01
Reference mixed neutron-gamma fields are used for test and calibration of dosimetric and spectrometric systems, intercomparison measurements, and benchmark tests and represent experimental base for reactor studies. Set of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation was build in the NRI Rez. Extended sets of measurements and simulation calculations were done to describe the reference mixed field dosimetry and spectral characteristics with best achievable precision. The Monte Carlo technique was used for different experimental setups models description, comparison and verification and field characteristics simulation. Effects (hardly distinguishable experimentally) were also studied ( contributions from individual parts of experimental setup, field individual components and next effects as shadow shield cones transparency, etc.). Some results and main conclusions of these studies and calculations are presented and discussed. (authors)
International Nuclear Information System (INIS)
Kluson, J.; Jansky, B.
2008-01-01
Reference mixed neutron-gamma fields are used for test and calibration of dosimetric and spectrometric systems, intercomparison measurements, and benchmark tests and represent experimental base for reactor studies. Set of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation was build in the NRI Rez. Extended sets of measurements and simulation calculations were done to describe the reference mixed field dosimetry and spectral characteristics with best achievable precision. The Monte Carlo technique was used for different experimental setups models description, comparison and verification and field characteristics simulation. Effects (hardly distinguishable experimentally) were also studied ( contributions from individual parts of experimental setup, field individual components and next effects as shadow shield cones transparency, etc.). Some results and main conclusions of these studies and calculations are presented and discussed. (authors)
International Nuclear Information System (INIS)
Rothe, R.E.
1997-12-01
Sixty-nine critical configurations of up to 186 kg of uranium are reported from very early experiments (1960s) performed at the Rocky Flats Critical Mass Laboratory near Denver, Colorado. Enriched (93%) uranium metal spherical and hemispherical configurations were studied. All were thick-walled shells except for two solid hemispheres. Experiments were essentially unreflected; or they included central and/or external regions of mild steel. No liquids were involved. Critical parameters are derived from extrapolations beyond subcritical data. Extrapolations, rather than more precise interpolations between slightly supercritical and slightly subcritical configurations, were necessary because experiments involved manually assembled configurations. Many extrapolations were quite long; but the general lack of curvature in the subcritical region lends credibility to their validity. In addition to delayed critical parameters, a procedure is offered which might permit the determination of prompt critical parameters as well for the same cases. This conjectured procedure is not based on any strong physical arguments
Mechanics of binary and polydisperse spherical pebble assembly
International Nuclear Information System (INIS)
Annabattula, R.K.; Gan, Y.; Kamlah, M.
2012-01-01
The micromechanical behavior of an assembly of binary and polydisperse spherical pebbles is studied using discrete element method (DEM) accounting for microscopic interactions between individual pebbles. A in-house DEM code has been used to simulate the assemblies consisting of different pebble diameters and the results of the simulations are compared with that of mono-size pebble assemblies. The effect of relative radii and volume fraction of the pebbles on the macroscopic stress–strain response is discussed. Furthermore, the effect of packing factor and coefficient of friction on the overall stress–strain behavior of the system is studied in detail. The shear (tangential) stiffness between the particles is also another influencing parameter. For a very small shear stiffness the system shows a strong dependence on the packing factor while a pebble material dependent shear stiffness shows a rather moderate dependence on the packing factor. For a similar packing factor, the mono-size assembly shows a stiff behavior during loading compared to binary assembly. However, the simulations do not show a significant difference between the two behaviors in contrast to the observations made in the experiments. The discrepancy can be attributed to (i) probable difference in packing factors for mono-size and binary assemblies in the experiments, (ii) arbitrary friction coefficient in the current model and (iii) the tangential interaction (constant shear stiffness) implemented in the present model which needs further modification as a function of the load history on the pebbles. Evolution of other micromechanical characteristics such as coordination number, contact force distribution and stored elastic energy of individual pebbles as a function of external load and system parameters is presented which can be used to estimate important macroscopic properties such as overall thermal conductivity and crushing resistance of the pebble beds.
Mechanics of binary and polydisperse spherical pebble assembly
Energy Technology Data Exchange (ETDEWEB)
Annabattula, R.K., E-mail: ratna.annabattula@kit.edu [Institute for Applied Materials (IAM-WBM), Karlsruhe Institute of Technology (KIT), D-76344, Eggenstein-Leopoldshafen (Germany); Gan, Y., E-mail: yixiang.gan@sydney.edu.au [School of Civil Engineering, University of Sydney, 2006 NSW, Sydney (Australia); Kamlah, M., E-mail: marc.kamlah@kit.edu [Institute for Applied Materials (IAM-WBM), Karlsruhe Institute of Technology (KIT), D-76344, Eggenstein-Leopoldshafen (Germany)
2012-08-15
The micromechanical behavior of an assembly of binary and polydisperse spherical pebbles is studied using discrete element method (DEM) accounting for microscopic interactions between individual pebbles. A in-house DEM code has been used to simulate the assemblies consisting of different pebble diameters and the results of the simulations are compared with that of mono-size pebble assemblies. The effect of relative radii and volume fraction of the pebbles on the macroscopic stress-strain response is discussed. Furthermore, the effect of packing factor and coefficient of friction on the overall stress-strain behavior of the system is studied in detail. The shear (tangential) stiffness between the particles is also another influencing parameter. For a very small shear stiffness the system shows a strong dependence on the packing factor while a pebble material dependent shear stiffness shows a rather moderate dependence on the packing factor. For a similar packing factor, the mono-size assembly shows a stiff behavior during loading compared to binary assembly. However, the simulations do not show a significant difference between the two behaviors in contrast to the observations made in the experiments. The discrepancy can be attributed to (i) probable difference in packing factors for mono-size and binary assemblies in the experiments, (ii) arbitrary friction coefficient in the current model and (iii) the tangential interaction (constant shear stiffness) implemented in the present model which needs further modification as a function of the load history on the pebbles. Evolution of other micromechanical characteristics such as coordination number, contact force distribution and stored elastic energy of individual pebbles as a function of external load and system parameters is presented which can be used to estimate important macroscopic properties such as overall thermal conductivity and crushing resistance of the pebble beds.
National Spherical Torus Experiment (NSTX) Torus Design, Fabrication and Assembly
International Nuclear Information System (INIS)
Neumeyer, C.; Barnes, G.; Chrzanowski, J.H.; Heitzenroeder, P.
1999-01-01
The National Spherical Torus Experiment (NSTX) is a low aspect ratio spherical torus (ST) located at Princeton Plasma Physics Laboratory (PPPL). Fabrication, assembly, and initial power tests were completed in February of 1999. The majority of the design and construction efforts were constructed on the Torus system components. The Torus system includes the centerstack assembly, external Poloidal and Toroidal coil systems, vacuum vessel, torus support structure and plasma facing components (PFC's). NSTX's low aspect ratio required that the centerstack be made with the smallest radius possible. This, and the need to bake NSTXs carbon-carbon composite plasma facing components at 350 degrees C, was major drivers in the design of NSTX. The Centerstack Assembly consists of the inner legs of the Toroidal Field (TF) windings, the Ohmic Heating (OH) solenoid and its associated tension cylinder, three inner Poloidal Field (PF) coils, thermal insulation, diagnostics and an Inconel casing which forms the inner wall of the vacuum vessel boundary. It took approximately nine months to complete the assembly of the Centerstack. The tight radial clearances and the extreme length of the major components added complexity to the assembly of the Centerstack components. The vacuum vessel was constructed of 304-stainless steel and required approximately seven months to complete and deliver to the Test Cell. Several of the issues associated with the construction of the vacuum vessel were control of dimensional stability following welding and controlling the permeability of the welds. A great deal of time and effort was devoted to defining the correct weld process and material selection to meet our design requirements. The PFCs will be baked out at 350 degrees C while the vessel is maintained at 150 degrees C. This required care in designing the supports so they can accommodate the high electromagnetic loads resulting from plasma disruptions and the resulting relative thermal expansions
Analysis of fission ratio distribution in spherical lithium metal assembly with a graphite reflector
International Nuclear Information System (INIS)
Seki, Yasushi; Maekawa, Hiroshi; Hiraoka, Toru; Hirota, Jitsuya; Moriyama, Masatoshi.
1975-08-01
For the investigation of neutronics in the fusion reactor blanket, a spherical lithium assembly with a graphite reflector was prepared by piling up lithium and graphite blocks. The ratio of U-238 to U-235 fission rates was measured by micro fission chambers, and the result of the measurement was compared with that of the preliminary calculation. It has been shown that there is a large discrepancy between experiment and calculation, which is too large to be explained only by the experimental error. In this paper, the calculational procedure is reviewed and probable causes of the calculational error are listed. Further calculation of the fission ratio is carried out employing refined methods and with varied calculational models. As the result, it is concluded that the cause of the discrepancy is most likely the uncertainties of the nuclear data of the constituent elements of the assembly. (auth.)
Fission blanket benchmark experiment on spherical assembly of uranium and PE with PE reflector
Energy Technology Data Exchange (ETDEWEB)
Zhu, Tonghua; Lu, Xinxin; Wang, Mei; Han, Zijie, E-mail: neutron_integral@aliyun.com; Jiang, Li; Wen, Zhongwei; Liu, Rong
2016-04-15
Highlights: • The fission rate distribution on two depleted uranium assemblies was measured with plate fission chambers. • We do calculations using MCNP code and ENDF/B-V.0 library. • The overestimation of calculations to the measured fission rates was found. • The observed discrepancy are discussed. - Abstract: New concept of fusion-fission hybrid for energy generation has been proposed. To validate the nuclear performance of fission blanket of hybrid, as part of series of validation experiment, two types of fission blanket assemblies were setup in this work and measurements were made of the reaction rate distribution for uranium fission in the spherical assembly of depleted uranium and polyethylene by Plate Fission Chamber (PFC). There are two PFCs in experiment, one is depleted uranium chamber and the other is enriched uranium chamber. The Monte-Carlo transport code MCNP5 and continuous energy cross sections library ENDF/BV.0 were used for the analysis of fission rate distribution in the two types of assemblies. The calculated results were compared with the experimental ones. The overestimation of fission rate for depleted uranium and enriched uranium were found in the inner boundary of the two assemblies. However, the C/E ratio tends to decrease for the distance from the core slightly and the results for enriched uranium are better than that for depleted uranium.
Wensrich, C. M.; Kisi, E. H.; Luzin, V.; Garbe, U.; Kirstein, O.; Smith, A. L.; Zhang, J. F.
2014-10-01
The full triaxial stress state within individual particles in a monodisperse spherical granular assembly has been measured. This was made possible by neutron imaging and computed tomography combined with neutron diffraction strain measurement techniques and associated stress reconstruction. The assembly in question consists of 549 precision steel ball bearings under an applied axial load of 85 MPa in a cylindrical die. Clear evidence of force chains was observed in terms of both the shape of the probability distribution function for normal stresses and the network formed by highly loaded particles. An extensive analysis of the source and magnitude of uncertainty in these measurements is also presented.
International Nuclear Information System (INIS)
Stanley, Jacob; Boucheron, Leandra; Shpyrko, Oleg; Lin, Binhua; Meron, Mati
2015-01-01
Recent developments in the synthesis of iron oxide nanoparticles have resulted in the ability to fabricate roughly spherical particles with extremely high size uniformity (low polydispersity). These particles can form self-assembled monolayer films at an air-water interface. When the polydispersity of the particles is low, these monolayers can be well-ordered over a length scale dozens of times the particle size. The van der Waals force between the particles is what drives this self-assembly. Through the use of Grazing Incidence X-Ray Diffraction we demonstrate that, when these films are formed at the liquid surface from bi-dispersed solutions containing 10 and 20 nm spherical particles suspended in chloroform, the particles phase separate into well-ordered patches during the self-assembly process. Furthermore, the domain sizes of these phase separated regions are at most 2–3 times smaller than that of a film comprising only mono-dispersed particles and their degree of disorder is comparable. This is shown for multiple solutions with differing ratios of 10 and 20 nm particles
Energy Technology Data Exchange (ETDEWEB)
Stanley, Jacob; Boucheron, Leandra; Shpyrko, Oleg, E-mail: lin@cars.uchicago.edu, E-mail: oshpyrko@physics.ucsd.edu [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Lin, Binhua, E-mail: lin@cars.uchicago.edu, E-mail: oshpyrko@physics.ucsd.edu; Meron, Mati [Center for Advanced Radiation Sources (CARS), University of Chicago, Chicago, Illinois 60637 (United States)
2015-04-20
Recent developments in the synthesis of iron oxide nanoparticles have resulted in the ability to fabricate roughly spherical particles with extremely high size uniformity (low polydispersity). These particles can form self-assembled monolayer films at an air-water interface. When the polydispersity of the particles is low, these monolayers can be well-ordered over a length scale dozens of times the particle size. The van der Waals force between the particles is what drives this self-assembly. Through the use of Grazing Incidence X-Ray Diffraction we demonstrate that, when these films are formed at the liquid surface from bi-dispersed solutions containing 10 and 20 nm spherical particles suspended in chloroform, the particles phase separate into well-ordered patches during the self-assembly process. Furthermore, the domain sizes of these phase separated regions are at most 2–3 times smaller than that of a film comprising only mono-dispersed particles and their degree of disorder is comparable. This is shown for multiple solutions with differing ratios of 10 and 20 nm particles.
Stereo Pinhole Camera: Assembly and experimental activities
Directory of Open Access Journals (Sweden)
Gilmário Barbosa Santos
2015-05-01
Full Text Available This work describes the assembling of a stereo pinhole camera for capturing stereo-pairs of images and proposes experimental activities with it. A pinhole camera can be as sophisticated as you want, or so simple that it could be handcrafted with practically recyclable materials. This paper describes the practical use of the pinhole camera throughout history and currently. Aspects of optics and geometry involved in the building of the stereo pinhole camera are presented with illustrations. Furthermore, experiments are proposed by using the images obtained by the camera for 3D visualization through a pair of anaglyph glasses, and the estimation of relative depth by triangulation is discussed.
Energy Technology Data Exchange (ETDEWEB)
Lell, R. M.; McKnight, R. D; Schaefer, R. W.; Nuclear Engineering Division
2010-09-30
Assembly 6F (ZPR-3/6F), the final phase of the Assembly 6 program, simulated a spherical core with a thick depleted uranium reflector. ZPR-3/6F was designed as a fast reactor physics benchmark experiment with an average core {sup 235}U enrichment of approximately 47 at.%. Approximately 81.4% of the total fissions in this assembly occur above 100 keV, approximately 18.6% occur below 100 keV, and essentially none below 0.625 eV - thus the classification as a 'fast' assembly. This assembly is Fast Reactor Benchmark No. 7 in the Cross Section Evaluation Working Group (CSEWG) Benchmark Specifications and has historically been used as a data validation benchmark assembly. Loading of ZPR-3/6F began in late December 1956, and the experimental measurements were performed in January 1957. The core consisted of highly enriched uranium (HEU) plates, depleted uranium plates, perforated aluminum plates and stainless steel plates loaded into aluminum drawers, which were inserted into the central square stainless steel tubes of a 31 x 31 matrix on a split table machine. The core unit cell consisted of three columns of 0.125 in.-wide (3.175 mm) HEU plates, three columns of 0.125 in.-wide depleted uranium plates, nine columns of 0.125 in.-wide perforated aluminum plates and one column of stainless steel plates. The maximum length of each column of core material in a drawer was 9 in. (228.6 mm). Because of the goal to produce an approximately spherical core, core fuel and diluent column lengths generally varied between adjacent drawers and frequently within an individual drawer. The axial reflector consisted of depleted uranium plates and blocks loaded in the available space in the front (core) drawers, with the remainder loaded into back drawers behind the front drawers. The radial reflector consisted of blocks of depleted uranium loaded directly into the matrix tubes. The assembly geometry approximated a reflected sphere as closely as the square matrix tubes, the drawers and the
Color from hierarchy: Diverse optical properties of micron-sized spherical colloidal assemblies.
Vogel, Nicolas; Utech, Stefanie; England, Grant T; Shirman, Tanya; Phillips, Katherine R; Koay, Natalie; Burgess, Ian B; Kolle, Mathias; Weitz, David A; Aizenberg, Joanna
2015-09-01
Materials in nature are characterized by structural order over multiple length scales have evolved for maximum performance and multifunctionality, and are often produced by self-assembly processes. A striking example of this design principle is structural coloration, where interference, diffraction, and absorption effects result in vivid colors. Mimicking this emergence of complex effects from simple building blocks is a key challenge for man-made materials. Here, we show that a simple confined self-assembly process leads to a complex hierarchical geometry that displays a variety of optical effects. Colloidal crystallization in an emulsion droplet creates micron-sized superstructures, termed photonic balls. The curvature imposed by the emulsion droplet leads to frustrated crystallization. We observe spherical colloidal crystals with ordered, crystalline layers and a disordered core. This geometry produces multiple optical effects. The ordered layers give rise to structural color from Bragg diffraction with limited angular dependence and unusual transmission due to the curved nature of the individual crystals. The disordered core contributes nonresonant scattering that induces a macroscopically whitish appearance, which we mitigate by incorporating absorbing gold nanoparticles that suppress scattering and macroscopically purify the color. With increasing size of the constituent colloidal particles, grating diffraction effects dominate, which result from order along the crystal's curved surface and induce a vivid polychromatic appearance. The control of multiple optical effects induced by the hierarchical morphology in photonic balls paves the way to use them as building blocks for complex optical assemblies--potentially as more efficient mimics of structural color as it occurs in nature.
Experimental Studies of Acoustics in a Spherical Couette Flow
Gowen, Savannah; Adams, Matthew; Stone, Douglas; Lathrop, Daniel
2016-11-01
The Earth, like many other astrophysical bodies, contains turbulent flows of conducting fluid which are able to sustain magnetic field. To investigate the hydromagnetic flow in the Earth's outer core, we have created an experiment which generates flows in liquid sodium. However, measuring these flows remains a challenge because liquid sodium is opaque. One possible solution is the use of acoustic waves. Our group has previously used acoustic wave measurements in air to infer azimuthal velocity profiles, but measurements attempted in liquid sodium remain challenging. In the current experiments we measure acoustic modes and their mode splittings in both air and water in a spherical Couette device. The device is comprised of a hollow 30-cm outer sphere which contains a smaller 10-cm rotating inner sphere to drive flow in the fluid in between. We use water because it has material properties that are similar to those of sodium, but is more convenient and less hazardous. Modes are excited and measured using a speaker and microphones. Measured acoustic modes and their mode splittings correspond well with the predicted frequencies in air. However, water modes are more challenging. Further investigation is needed to understand acoustic measurements in the higher density media.
Color from hierarchy: Diverse optical properties of micron-sized spherical colloidal assemblies
Vogel, Nicolas; Utech, Stefanie; England, Grant T.; Shirman, Tanya; Phillips, Katherine R.; Koay, Natalie; Burgess, Ian B.; Kolle, Mathias; Weitz, David A.; Aizenberg, Joanna
2015-01-01
Materials in nature are characterized by structural order over multiple length scales have evolved for maximum performance and multifunctionality, and are often produced by self-assembly processes. A striking example of this design principle is structural coloration, where interference, diffraction, and absorption effects result in vivid colors. Mimicking this emergence of complex effects from simple building blocks is a key challenge for man-made materials. Here, we show that a simple confined self-assembly process leads to a complex hierarchical geometry that displays a variety of optical effects. Colloidal crystallization in an emulsion droplet creates micron-sized superstructures, termed photonic balls. The curvature imposed by the emulsion droplet leads to frustrated crystallization. We observe spherical colloidal crystals with ordered, crystalline layers and a disordered core. This geometry produces multiple optical effects. The ordered layers give rise to structural color from Bragg diffraction with limited angular dependence and unusual transmission due to the curved nature of the individual crystals. The disordered core contributes nonresonant scattering that induces a macroscopically whitish appearance, which we mitigate by incorporating absorbing gold nanoparticles that suppress scattering and macroscopically purify the color. With increasing size of the constituent colloidal particles, grating diffraction effects dominate, which result from order along the crystal’s curved surface and induce a vivid polychromatic appearance. The control of multiple optical effects induced by the hierarchical morphology in photonic balls paves the way to use them as building blocks for complex optical assemblies—potentially as more efficient mimics of structural color as it occurs in nature. PMID:26290583
DEFF Research Database (Denmark)
Bjelogrlic, Mina; Volery, Maxime; Fuchs, Benjamin
2018-01-01
This work presents the analysis of power transmission of a radiating field inside the human head for microwave imaging applications. For this purpose, a spherical layered model composed of dispersive biological tissues is investigated in the range of (0.5–4) GHz and is confronted to experimental ...
Experimental analysis of the influence of damping on the resonance behavior of a spherical pendulum
Czech Academy of Sciences Publication Activity Database
Pospíšil, Stanislav; Fischer, Cyril; Náprstek, Jiří
2014-01-01
Roč. 78, č. 1 (2014), s. 371-390 ISSN 0924-090X R&D Projects: GA ČR(CZ) GC13-34405J Grant - others:NSC(TW) 101WFD0400131 Institutional support: RVO:68378297 Keywords : auto -parametric system * experimental verification * spherical pendulum * stability of semi-trivial solution Subject RIV: JM - Building Engineering Impact factor: 2.849, year: 2014 http://link.springer.com/article/10.1007%2Fs11071-014-1446-6#page-1
International Nuclear Information System (INIS)
Brossard, J.
1978-01-01
The characteristics of the pressure waves transmitted by detonation of gaseous mixtures to the surrounding air were measured by tests made near the ground level in 1 to 54 m 3 spherical balloons containing air-acetylene or air-ethylene mixtures. As concerns the peak overpressure Δp, a theoretical dimensional analysis in accordance with the experimental results shows that Δp can be expressed as a function of two independent variables, which are the radial distance R and the volume V of the balloon . A semi-empirical formula, including ground effects, is proposed and its present validity range is given. (author)
Interplay between spherical confinement and particle shape on the self-assembly of rounded cubes.
Wang, Da; Hermes, Michiel; Kotni, Ramakrishna; Wu, Yaoting; Tasios, Nikos; Liu, Yang; de Nijs, Bart; van der Wee, Ernest B; Murray, Christopher B; Dijkstra, Marjolein; van Blaaderen, Alfons
2018-06-08
Self-assembly of nanoparticles (NPs) inside drying emulsion droplets provides a general strategy for hierarchical structuring of matter at different length scales. The local orientation of neighboring crystalline NPs can be crucial to optimize for instance the optical and electronic properties of the self-assembled superstructures. By integrating experiments and computer simulations, we demonstrate that the orientational correlations of cubic NPs inside drying emulsion droplets are significantly determined by their flat faces. We analyze the rich interplay of positional and orientational order as the particle shape changes from a sharp cube to a rounded cube. Sharp cubes strongly align to form simple-cubic superstructures whereas rounded cubes assemble into icosahedral clusters with additionally strong local orientational correlations. This demonstrates that the interplay between packing, confinement and shape can be utilized to develop new materials with novel properties.
Storey, Jedediah Morse
2016-01-01
Understanding, predicting, and controlling fluid slosh dynamics is critical to safety and improving performance of space missions when a significant percentage of the spacecraft's mass is a liquid. Computational fluid dynamics simulations can be used to predict the dynamics of slosh, but these programs require extensive validation. Many experimental and numerical studies of water slosh have been conducted. However, slosh data for cryogenic liquids is lacking. Water and cryogenic liquid nitrogen are used in various ground-based tests with a spherical tank to characterize damping, slosh mode frequencies, and slosh forces. A single ring baffle is installed in the tank for some of the tests. Analytical models for slosh modes, slosh forces, and baffle damping are constructed based on prior work. Select experiments are simulated using a commercial CFD software, and the numerical results are compared to the analytical and experimental results for the purposes of validation and methodology-improvement.
Steinhaus, Andrea; Pelras, Théophile; Chakroun, Ramzi; Gröschel, André H; Müllner, Markus
2018-05-02
Understanding the self-assembly behavior of polymers of various topologies is key to a reliable design of functional polymer materials. Self-assembly under confinement conditions emerges as a versatile avenue to design polymer particles with complex internal morphologies while simultaneously facilitating scale-up. However, only linear block copolymers have been studied to date, despite the increasing control over macromolecule composition and architecture available. This study extends the investigation of polymer self-assembly in confinement from regular diblock copolymers to diblock molecular polymer brushes (MPBs). Block-type MPBs with polystyrene (PS) and polylactide (PLA) compartments of different sizes are incorporated into surfactant-stabilized oil-in-water (chloroform/water) emulsions. The increasing confinement in the nanoemulsion droplets during solvent evaporation directs the MPBs to form solid nano/microparticles. Microscopy studies reveal an intricate internal particle structure, including interpenetrating networks and axially stacked lamellae of PS and PLA, depending on the PS/PLA ratio of the brushes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
SNEAK assembly 12B - Construction and experimental program
International Nuclear Information System (INIS)
Helm, F.
1982-10-01
The assembly SNEAK 12A is the second SNEAK assembly in which the neutron physics of disturbed material configurations, as they might occur in a postulated fast reactor accident, is investigated. The core is characterized by a central zone with fuel rods containing PuO 2 UO 2 mixed oxide pellets. This zone is cylindrically surrounded by a buffer zone for spectral adaptation, a driver zone sufficiently reactive to maintain criticality and a radial depleted uranium blanket. The purpose of the experiments is to test calculational methods of neutron physics which are used in the accident analysis of fast breeder reactors. The report describes the construction of the core and its assemblies and their content and outlines the foreseen experimental program. It includes measurements in the clean critical core and investigations of vertical and horizontal fuel relocations and steel blockages
Directory of Open Access Journals (Sweden)
Shewale Vinod C.
2017-01-01
Full Text Available Spherical cavity receiver of solar concentrator is made up of Cu tubing material having cavity diameter 385 mm to analyze the different heat losses such as conduction, convection and radiation. As the convection loss plays major role in heat loss analysis of cavity receiver, the experimental analysis is carried out to study convective heat loss for the temperature range of 55-75°C at 0°, 15°, 30°, 45°, 60°, and 90° inclination angle of downward facing cavity receiver. The numerical analysis is carried out to study convective heat loss for the low temperature range (55-75°C as well as high temperature range (150-300 °C for no wind condition only. The experimental set-up mainly consists of spherical cavity receiver which is insulated with glass wool insulation to reduce the heat losses from outside surface. The numerical analysis is carried out by using CFD software and the results are compared with the experimental results and found good agreement. The result shows that the convective loss increases with decrease in cavity inclination angle and decreases with decrease in mean cavity receiver temperature. The maximum losses are obtained at 0° inclination angle and the minimum losses are obtained at 90° inclination angle of cavity due to increase in stagnation zone in to the cavity from 0° to 90° inclination. The Nusselt number correlation is developed for the low temperature range 55-75°C based on the experimental data. The analysis is also carried out to study the effect of wind speed and wind direction on convective heat losses. The convective heat losses are studied for two wind speeds (3 m/s and 5 m/s and four wind directions [α is 0° (Side-on wind, 30°, 60°, and 90° (head-on wind]. It is found that the convective heat losses for both wind speed are higher than the losses obtained by no wind test. The highest heat losses are found for wind direction α is 60° with respect to receiver stand and lowest heat losses are found
Xia, Huicong; Zhang, Jianan; Yang, Zhao; Guo, Shiyu; Guo, Shihui; Xu, Qun
2017-10-01
Metal-organic frameworks (MOFs) are of great interest as potential electrochemically active materials. However, few studies have been conducted into understanding whether control of the shape and components of MOFs can optimize their electrochemical performances due to the rational realization of their shapes. Component control of MOFs remains a significant challenge. Herein, we demonstrate a solvothermal method to realize nanostructure engineering of 2D nanoflake MOFs. The hollow structures with Ni/Co- and Ni-MOF (denoted as Ni/Co-MOF nanoflakes and Ni-MOF nanoflakes) were assembled for their electrochemical performance optimizations in supercapacitors and in the oxygen reduction reaction (ORR). As a result, the Ni/Co-MOF nanoflakes exhibited remarkably enhanced performance with a specific capacitance of 530.4 F g-1 at 0.5 A g-1 in 1 M LiOH aqueous solution, much higher than that of Ni-MOF (306.8 F g-1) and ZIF-67 (168.3 F g-1), a good rate capability, and a robust cycling performance with no capacity fading after 2000 cycles. Ni/Co-MOF nanoflakes also showed improved electrocatalytic performance for the ORR compared to Ni-MOF and ZIF-67. The present work highlights the significant role of tuning 2D nanoflake ensembles of Ni/Co-MOF in accelerating electron and charge transportation for optimizing energy storage and conversion devices. [Figure not available: see fulltext.
Antonopoulou, Evangelia; Rohmann-Shaw, Connor F.; Sykes, Thomas C.; Cayre, Olivier J.; Hunter, Timothy N.; Jimack, Peter K.
2018-03-01
Understanding the sedimentation behaviour of colloidal suspensions is crucial in determining their stability. Since sedimentation rates are often very slow, centrifugation is used to expedite sedimentation experiments. The effect of centrifugal acceleration on sedimentation behaviour is not fully understood. Furthermore, in sedimentation models, interparticle interactions are usually omitted by using the hard-sphere assumption. This work proposes a one-dimensional model for sedimentation using an effective maximum volume fraction, with an extension for sedimentation under centrifugal force. A numerical implementation of the model using an adaptive finite difference solver is described. Experiments with silica suspensions are carried out using an analytical centrifuge. The model is shown to be a good fit with experimental data for 480 nm spherical silica, with the effects of centrifugation at 705 rpm studied. A conversion of data to Earth gravity conditions is proposed, which is shown to recover Earth gravity sedimentation rates well. This work suggests that the effective maximum volume fraction accurately captures interparticle interactions and provides insights into the effect of centrifugation on sedimentation.
Experimental study of parametric dependence of electron-scale turbulence in a spherical tokamak
Energy Technology Data Exchange (ETDEWEB)
Ren, Y.; Guttenfelder, W.; Kaye, S. M.; Mazzucato, E.; Bell, R. E.; Diallo, A.; LeBlanc, B. P. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Domier, C. W.; Lee, K. C. [University of California at Davis, Davis, California 95616 (United States); Smith, D. R. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Yuh, H. [Nova Photonics, Inc., Princeton, New Jersey 08540 (United States)
2012-05-15
Electron-scale turbulence is predicted to drive anomalous electron thermal transport. However, experimental study of its relation with transport is still in its early stage. On the National Spherical Tokamak Experiment (NSTX), electron-scale density fluctuations are studied with a novel tangential microwave scattering system with high radial resolution of {+-}2 cm. Here, we report a study of parametric dependence of electron-scale turbulence in NSTX H-mode plasmas. The dependence on density gradient is studied through the observation of a large density gradient variation in the core induced by an edge localized mode (ELM) event, where we found the first clear experimental evidence of density gradient stabilization of electron-gyro scale turbulence in a fusion plasma. This observation, coupled with linear gyro-kinetic calculations, leads to the identification of the observed instability as toroidal electron temperature gradient (ETG) modes. It is observed that longer wavelength ETG modes, k{sub Up-Tack }{rho}{sub s} Less-Than-Or-Equivalent-To 10 ({rho}{sub s} is the ion gyroradius at electron temperature and k{sub Up-Tack} is the wavenumber perpendicular to local equilibrium magnetic field), are most stabilized by density gradient, and the stabilization is accompanied by about a factor of two decrease in electron thermal diffusivity. Comparisons with nonlinear ETG gyrokinetic simulations show ETG turbulence may be able to explain the experimental electron heat flux observed before the ELM event. The collisionality dependence of electron-scale turbulence is also studied by systematically varying plasma current and toroidal field, so that electron gyroradius ({rho}{sub e}), electron beta ({beta}{sub e}), and safety factor (q{sub 95}) are kept approximately constant. More than a factor of two change in electron collisionality, {nu}{sub e}{sup *}, was achieved, and we found that the spectral power of electron-scale turbulence appears to increase as {nu}{sub e}{sup *} is
International Nuclear Information System (INIS)
Ichihara, Chihiro; Fujine, Shigenori; Hayashi, Masatoshi
1986-01-01
The Kyoto University critical assembly experimental facilities belong to the Kyoto University Research Reactor Institute, and are the versatile critical assembly constructed for experimentally studying reactor physics and reactor engineering. The facilities are those for common utilization by universities in whole Japan. During more than ten years since the initial criticality in 1974, various experiments on reactor physics and reactor engineering have been carried out using many experimental facilities such as two solidmoderated cores, a light water-moderated core and a neutron generator. The kinds of the experiment carried out were diverse, and to find out the required data from them is very troublesome, accordingly it has become necessary to make a data base which can be processed by a computer with the data accumulated during the past more than ten years. The outline of the data base, the data base CAEX using personal computers, the data base supported by a large computer and so on are reported. (Kako, I.)
International Nuclear Information System (INIS)
Krause, F.
1986-01-01
In the period from 1980 to 1985, in the Rheinsberg nuclear power plant experimental fuel assemblies were used on lattices at the periphery of the core. These particular fuel assemblies dispose of an extensive in-core instrumentation with different sensors. Besides this, they are fit out with a device to systematically thottle the coolant flow. The large power gradient present at the core position of the experimental fuel assembly causes a temperature profile along the fuel assemblies which is well provable at the measuring points of the outlet temperature. Along the direction of flow this temperature profile in the coolant degrades only slowly. This effect is to be taken into account when measuring the fuel assembly outlet temperature of WWER fuel assemblies. Besides this, the results of the measurements hinted both at a γ-heating of the temperature measuring points and at tolerances in the calculation of the micro power density distribution. (author)
Experimental study on practicability of self-created spherical tokamak in coilless STPC-EX machine
International Nuclear Information System (INIS)
Sinman, S.
2002-01-01
The aim of this study is to recognize the physical basis of the alternative self organization mechanism occurred STPC-EX machine. The conventional diagnostic tools are used in this study and for photographic recording, open shutter integrated post-fogging method is preferred. The annular coaxial two plasma current sheets one within other at the same direction are created and flowed on the surface of floating conductive central rod. Consequently, spherical tokamak configurated by new creation mechanism of Dual Axial Z-Pinch. (DAZP) yields fairly high beta of 0.4-0.6 at self created spherical tokamak plasma. Sustainment time of DAZP is 5.6-6.3 mili second. (author)
Energy Technology Data Exchange (ETDEWEB)
Koch, S; Harlander, U; Egbers, C [Department of Aerodynamics and Fluid Mechanics, Brandenburg University of Technology Cottbus, Siemens-Halske-Ring 14, D-03046 Cottbus (Germany); Hollerbach, R, E-mail: uwe.harlander@tu-cottbus.de [Institute of Geophysics, ETH Zuerich, Sonneggstrasse 5, CH-8092 Zurich (Switzerland)
2013-06-15
We begin with an experimental investigation of the flow induced in a rotating spherical shell. The shell globally rotates with angular velocity {Omega}. A further periodic oscillation with angular velocity 0 Less-Than-Or-Slanted-Equal-To {omega} Less-Than-Or-Slanted-Equal-To 2{Omega}, a so-called longitudinal libration, is added on the inner sphere's rotation. The primary response is inertial waves spawned at the critical latitudes on the inner sphere, and propagating throughout the shell along inclined characteristics. For sufficiently large libration amplitudes, the higher harmonics also become important. Those harmonics whose frequencies are still less than 2{Omega} behave as inertial waves themselves, propagating along their own characteristics. The steady component of the flow consists of a prograde zonal jet on the cylinder tangent to the inner sphere and parallel to the axis of rotation, and increases with decreasing Ekman number. The jet becomes unstable for larger forcing amplitudes as can be deduced from the preliminary particle image velocimetry observations. Finally, a wave attractor is experimentally detected in the spherical shell as the pattern of largest variance. These findings are reproduced in a two-dimensional numerical investigation of the flow, and certain aspects can be studied numerically in greater detail. One aspect is the scaling of the width of the inertial shear layers and the width of the steady jet. Another is the partitioning of the kinetic energy between the forced wave, its harmonics and the mean flow. Finally, the numerical simulations allow for an investigation of instabilities, too local to be found experimentally. For strong libration amplitudes, the boundary layer on the inner sphere becomes unstable, triggering localized Goertler vortices during the prograde phase of the forcing. This instability is important for the transition to turbulence of the spherical shell flow. (paper)
Experimental Studies on Assemblies 1 and 2 of the Fast Reactor FR-0. Part 1
Energy Technology Data Exchange (ETDEWEB)
Andersson, T L; Hellstrand, E; Londen, S O; Tiren, L I
1965-08-15
FR0 is a fast zero power reactor built for experiments in reactor physics. It is a split table machine containing vertical fuel elements. 120 kg of U{sup 235} are available as fuel, which is fabricated into metallic plates of 20 % enrichment. The control system comprises 5 spring-loaded safety elements and 3 + 1 elements for startup operations and power control. The reactor went critical in February 1964. The first assemblies studied were made up of undiluted fuel into a cylindrical and a spherical core, respectively, surrounded by a reflector made of copper. The present report describes some experiments made on these systems. Primarily, critical mass determinations, flux distribution measurements and studies of the conversion ratio are dealt with. The measured quantities have been compared with theoretical predictions using various transport theory programmes (DSN, TDC) and cross section sets. The experimental results show that the neutron spectrum in the copper reflector is softer than predicted, but apart from this discrepancy agreement with theory has generally been obtained.
International Nuclear Information System (INIS)
Asfia, F.; Dhir, V.
1998-03-01
One strategy for preventing the failure of lower head of a nuclear reactor vessel is to flood the concrete cavity with subcooled water in accidents in which relocation of core material into the vessel lower head occurs. After the core material relocates into the vessel, a crust of solid material forms on the inner wall of the vessel, however, most of the pool remains molten and natural convection exists in the pool. At present, uncertainty exists with respect to natural convection heat transfer coefficients between the pool of molten core material and the reactor vessel wall. In the present work, experiments were conducted to examine natural convection heat transfer in internally heated partially filled spherical pools with external cooling. In the experiments, Freon-113 contained in a Pyrex bell jar was used as a test liquid. The pool was bounded with a spherical segment at the bottom, and was heated with magnetrons taken from a conventional microwave oven. The vessel was cooled from the outside with natural convection of water or with nucleate boiling of liquid nitrogen
International Nuclear Information System (INIS)
Majeed, Shafquat; Shivashankar, S.A.
2013-01-01
We report the synthesis of Pr 6 O 11 microspheres self-assembled from ultra-small nanocrystals formed by the microwave irradiation of a solution of a salt of Pr in ethylene glycol (EG). The as-prepared product consists of microspheres measuring 200 to 500 nm in diameter and made of 6 O 11 microspheres assembled from ultra-small nanocrystals were synthesized. • As-prepared microspheres are covered by ethylene glycol as shown by IR analysis. • Role of temperature and pressure on self-assembly studied. • Luminescence emission behaviour of as-prepared and annealed products studied
Experimental and modeling studies of small molecule chemistry in expanding spherical flames
Santner, Jeffrey
Accurate models of flame chemistry are required in order to predict emissions and flame properties, such that clean, efficient engines can be designed more easily. There are three primary methods used to improve such combustion chemistry models - theoretical reaction rate calculations, elementary reaction rate experiments, and combustion system experiments. This work contributes to model improvement through the third method - measurements and analysis of the laminar burning velocity at constraining conditions. Modern combustion systems operate at high pressure with strong exhaust gas dilution in order to improve efficiency and reduce emissions. Additionally, flames under these conditions are sensitized to elementary reaction rates such that measurements constrain modeling efforts. Measurement conditions of the present work operate within this intersection between applications and fundamental science. Experiments utilize a new pressure-release, heated spherical combustion chamber with a variety of fuels (high hydrogen content fuels, formaldehyde (via 1,3,5-trioxane), and C2 fuels) at pressures from 0.5--25 atm, often with dilution by water vapor or carbon dioxide to flame temperatures below 2000 K. The constraining ability of these measurements depends on their uncertainty. Thus, the present work includes a novel analytical estimate of the effects of thermal radiative heat loss on burning velocity measurements in spherical flames. For 1,3,5-trioxane experiments, global measurements are sufficiently sensitive to elementary reaction rates that optimization techniques are employed to indirectly measure the reaction rates of HCO consumption. Besides the influence of flame chemistry on propagation, this work also explores the chemistry involved in production of nitric oxide, a harmful pollutant, within flames. We find significant differences among available chemistry models, both in mechanistic structure and quantitative reaction rates. There is a lack of well
Energy Technology Data Exchange (ETDEWEB)
Kim, YooSung; Shi, Yue-Jiang, E-mail: yjshi@snu.ac.kr; Yang, Jeong-hun; Kim, SeongCheol; Kim, Young-Gi; Dang, Jeong-Jeung; Yang, Seongmoo; Jo, Jungmin; Chung, Kyoung-Jae [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Oh, Soo-Ghee [Division of Energy Systems Research, Ajou University, Suwon 442-749 (Korea, Republic of); Hwang, Y. S. [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Center for Advanced Research in Fusion Reactor Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)
2016-11-15
Electron density profiles of versatile experiment spherical torus plasmas are measured by using a hydrogen line intensity ratio method. A fast-frame visible camera with appropriate bandpass filters is used to detect images of Balmer line intensities. The unique optical system makes it possible to take images of H{sub α} and H{sub β} radiation simultaneously, with only one camera. The frame rate is 1000 fps and the spatial resolution of the system is about 0.5 cm. One-dimensional local emissivity profiles have been obtained from the toroidal line of sight with viewing dumps. An initial result for the electron density profile is presented and is in reasonable agreement with values measured by a triple Langmuir probe.
Experimental study of potential structure in a spherical IEC fusion device
International Nuclear Information System (INIS)
Gu, Y.; Miley, G.H.
2000-01-01
The spherical inertial-electrostatic confinement (SIEC) concept is designed to focus and accelerate ions and electrons radially inward towards the center of a negatively biased, highly transparent spherical grid. The converging ions create a high-density plasma core where a high fusion rate occurs. In addition, under proper conditions, the ion and electron flows create a space-charge induced double potential well (a negative potential well nested inside a positive potential well). This structure traps high-energy ions within the virtual anode created by the double potential, providing a high fusion density in the trap volume. The present experiment was designed to verify double potential well formation and trapping by a measurement of the radial birth profile of energetic (3-MeV) protons produced by D-D fusion reactions in a deuterium discharge. This experiment was designed to operate at high perveance (0.4 to 1.4 mA/kV 3/2 ), where formation of a double well is predicted theoretically. Additional steps to aid well formation included: use of the unique Star mode of operation to obtain ion beam focusing down to approximately 1.6 H the ballistic limit and the incorporation of a second electrically floating grid (in addition to the focusing/accelerating cathode grid) to reduce the ion radial energy spread to 0.34 mA/kV 3/2 . As the perveance increased, the depth of the double well also increased. At the maximum perveance studied, 1.38 mA/kV 3/2 (corresponding to 80 mA and 15 kV), the negative potential well depth, corresponding to the measured proton-rate density, was estimated to be 22%--27% of the applied cathode voltage. This represents the first conclusive demonstration of double well formation in an SIEC, since prior measurements by other researchers typically yielded marginal or negative results
A Theoretical and Experimental Study of DNA Self-assembly
Chandran, Harish
The control of matter and phenomena at the nanoscale is fast becoming one of the most important challenges of the 21st century with wide-ranging applications from energy and health care to computing and material science. Conventional top-down approaches to nanotechnology, having served us well for long, are reaching their inherent limitations. Meanwhile, bottom-up methods such as self-assembly are emerging as viable alternatives for nanoscale fabrication and manipulation. A particularly successful bottom up technique is DNA self-assembly where a set of carefully designed DNA strands form a nanoscale object as a consequence of specific, local interactions among the different components, without external direction. The final product of the self-assembly process might be a static nanostructure or a dynamic nanodevice that performs a specific function. Over the past two decades, DNA self-assembly has produced stunning nanoscale objects such as 2D and 3D lattices, polyhedra and addressable arbitrary shaped substrates, and a myriad of nanoscale devices such as molecular tweezers, computational circuits, biosensors and molecular assembly lines. In this dissertation we study multiple problems in the theory, simulations and experiments of DNA self-assembly. We extend the Turing-universal mathematical framework of self-assembly known as the Tile Assembly Model by incorporating randomization during the assembly process. This allows us to reduce the tile complexity of linear assemblies. We develop multiple techniques to build linear assemblies of expected length N using far fewer tile types than previously possible. We abstract the fundamental properties of DNA and develop a biochemical system, which we call meta-DNA, based entirely on strands of DNA as the only component molecule. We further develop various enzyme-free protocols to manipulate meta-DNA systems and provide strand level details along with abstract notations for these mechanisms. We simulate DNA circuits by
Status and Plans for the National Spherical Torus Experimental Research Facility
International Nuclear Information System (INIS)
Ono, M.; Bell, M.G.; Bell, R.E.; Bialek, J.M.; Bigelow, T.; Bitter, M.
2005-01-01
An overview of the research capabilities and the future plans on the MA-class National Spherical Torus Experiment (NSTX) at Princeton is presented. NSTX research is exploring the scientific benefits of modifying the field line structure from that in more conventional aspect ratio devices, such as the tokamak. The relevant scientific issues pursued on NSTX include energy confinement, MHD stability at high beta, non-inductive sustainment, solenoid-free start-up, and power and particle handling. In support of the NSTX research goal, research tools are being developed by the NSTX team. In the context of the fusion energy development path being formulated in the US, an ST-based Component Test Facility (CTF) and, ultimately a high beta Demo device based on the ST, are being considered. For these, it is essential to develop high performance (high beta and high confinement), steady-state (non-inductively driven) ST operational scenarios and an efficient solenoid-free start-up concept. We will also briefly describe the Next-Step-ST (NSST) device being designed to address these issues in fusion-relevant plasma conditions
Status and plans for the national spherical torus experimental research facility
International Nuclear Information System (INIS)
Ono, Masayuki; Bell, M.G.; Bell, R.E.
2005-01-01
An overview of the research capabilities and the future plans on the MA-class National Spherical Torus Experiment (NSTX) at Princeton is presented. NSTX research is exploring the scientific benefits of modifying the field line structure from that in more conventional aspect ratio devices, such as the tokamak. The relevant scientific issues pursued on NSTX include energy confinement, MHD stability at high β, non-inductive sustainment, solenoid-free start-up, and power and particle handling. In support of the NSTX research goal, research tools are being developed by the NSTX team. In the context of the fusion energy development path being formulated in the US, an ST-based Component Test Facility (CTF) and, ultimately a high β Demo device based on the ST, are being considered. For these, it is essential to develop high performance (high β and high confinement), steady-state (non-inductively driven) ST operational scenarios and an efficient solenoid-free start-up concept. We will also briefly describe the Next-Step-ST (NSST) device being designed to address these issues in fusion-relevant plasma conditions. (author)
Experimental study of new generation WWER-1000 fuel assemblies at JSC NCCP
International Nuclear Information System (INIS)
Enin, A.; Rozhkov, V.; Sinikov, Y.; Ustimenko, A.; Shustov, M.
2003-01-01
An experimental program for the study of fuel assembly thermomechanical stability has been established together with RF SSC IPPE and Russian Scientific Center Kurchatov Institute. Assembly fragments and small dummy models of fuel assembly skeletons and fuel rod bundles have been used for the tests. The test results are used for the design selection, verification of the design codes and substantiation of operating capacity of fuel assemblies with a rigid skeleton. The mechanical characteristics of units make it possible to perform fuel assembly strength and rigidity calculations, including the cases of abnormal operation. The mechanical characteristics of the skeleton and fuel rod bundle dummy models make it possible to check for the adequacy of the fuel assembly design model. The mechanical characteristics obtained during fuel rods bundle push through experiments make it possible to substantiate the fuel assembly serviceability under the conditions of fuel rods bundle and skeleton interaction
Johnson, Kennita A.; Vormohr, Hannah R.; Doinikov, Alexander A.; Bouakaz, Ayache; Shields, C. Wyatt; López, Gabriel P.; Dayton, Paul A.
2016-05-01
Acoustophoresis uses acoustic radiation force to remotely manipulate particles suspended in a host fluid for many scientific, technological, and medical applications, such as acoustic levitation, acoustic coagulation, contrast ultrasound imaging, ultrasound-assisted drug delivery, etc. To estimate the magnitude of acoustic radiation forces, equations derived for an inviscid host fluid are commonly used. However, there are theoretical predictions that, in the case of a traveling wave, viscous effects can dramatically change the magnitude of acoustic radiation forces, which make the equations obtained for an inviscid host fluid invalid for proper estimation of acoustic radiation forces. To date, experimental verification of these predictions has not been published. Experimental measurements of viscous effects on acoustic radiation forces in a traveling wave were conducted using a confocal optical and acoustic system and values were compared with available theories. Our results show that, even in a low-viscosity fluid such as water, the magnitude of acoustic radiation forces is increased manyfold by viscous effects in comparison with what follows from the equations derived for an inviscid fluid.
Energy Technology Data Exchange (ETDEWEB)
Dundulis, Gintautas [Laboratory of Nuclear Installation Safety, Lithuanian Energy Institute, Breslaujos Street 3, LT-44403 Kaunas (Lithuania)], E-mail: gintas@mail.lei.lt; Grybenas, Albertas [Laboratory of Materials Research and Testing, Lithuanian Energy Institute, Breslaujos Street 3, LT-44403 Kaunas (Lithuania); Karalevicius, Renatas [Laboratory of Nuclear Installation Safety, Lithuanian Energy Institute, Breslaujos Street 3, LT-44403 Kaunas (Lithuania); Makarevicius, Vidas [Laboratory of Materials Research and Testing, Lithuanian Energy Institute, Breslaujos Street 3, LT-44403 Kaunas (Lithuania); Rimkevicius, Sigitas; Uspuras, Eugenijus [Laboratory of Nuclear Installation Safety, Lithuanian Energy Institute, Breslaujos Street 3, LT-44403 Kaunas (Lithuania)
2009-01-15
The Ignalina Nuclear Power Plant (NPP) has two RBMK-1500 graphite-moderated boiling water multi-channel reactors. The Ignalina NPP Unit 1 was shutdown at the end of 2004, while Unit 2 is foreseen to be shutdown at the end of 2009. At the Ignalina NPP Unit 1 remains approximately 1000 spent fuel assemblies with low burn-up depth. A special set of equipment was developed to reuse these assemblies in the reactor of Unit 2. One of most important items of this set is a container, which is used for the transportation of spent fuel assemblies between the reactors of Unit 1 and Unit 2. A special shock absorber was designed to avoid failure of fuel assemblies in case of hypothetical spent fuel assemblies drop accident during uploading/unloading of spent fuel assemblies to/from container. This shock absorber was examined by using scaled experiments. The objective of this article is the estimation whether the proposed design of shock absorber fulfils the function of the absorber and the optimization of its geometrical parameters using the results of the performed investigations. Static analytical and experimental investigations are presented in the article. The finite element code BRIGADE/Plus was used for the analytical analysis. The calculation model was verified by comparing the experimental investigation and simulation results for further employment of this finite element model in the development of an optimum design of shock absorber. Static simulation was used to perform primary optimization of design and dimension of the shock absorber.
Experimental determination of the neutron source for the Argonauta reactor subcritical assembly
Energy Technology Data Exchange (ETDEWEB)
Renke, Carlos A.C.; Furieri, Rosanne C.A.A.; Pereira, Joao C.S.; Voi, Dante L.; Barbosa, Andre L.N., E-mail: renke@ien.gov.b [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)
2011-07-01
The utilization of a subcritical assembly for the determination of nuclear parameters in a multiplier medium requires a well defined neutron source to carry out the experiments necessary for the acquisition of the desired data. The Argonauta research reactor installed at the Instituto de Engenharia Nuclear has a subcritical assembly, under development, to be coupled at the upper part of the reactor core that will provide the needed neutrons emerging from its internal thermal column made of graphite. In order to perform neutronic calculations to compare with the experimental results, it is necessary a precise knowledge of the emergent neutron flux that will be used as neutron source in the subcritical assembly. In this work, we present the thermal neutron flux profile determined experimentally via the technique of neutron activation analysis, using dysprosium wires uniformly distributed at the top of the internal thermal neutron column of the Argonauta reactor and later submitted to a detection system using Geiger-Mueller detector. These experimental data were then compared with those obtained through neutronic calculation using HAMMER and CITATION codes in order to validate this calculation system and to define a correct neutron source distribution to be used in the subcritical assembly. This procedure avoids a coupled neutronic calculation of the subcritical assembly and the reactor core. It has also been determined the dimension of the graphite pedestal to be used in the bottom of the subcritical assembly tank in order to smooth the emergent neutron flux at the reactor top. Finally, it is estimated the thermal neutron flux inside the assembly tank when filled with water. (author)
International Nuclear Information System (INIS)
Okitsu, Kouhei; Iida, Satoshi; Sugita, Yoshimitsu; Takeno, Hiroshi; Yagou, Yasuyoshi; Kawata, Hiroshi.
1992-01-01
An undoped floating zone (FZ) silicon crystal has been investigated by synchrotron X-radiation section topography with high-order reflections up to 14 14 0. Numerically simulated topographs based on the Takagi-Taupin equations were in good agreement with experimental distorted patterns when a spherical strain field was assumed in the crystal. The volume change of the lattice caused by the strain center was estimated to correspond to a sphere with a radius of 10 μm. (author)
Energy Technology Data Exchange (ETDEWEB)
Dundulis, Gintautas, E-mail: gintas@mail.lei.lt [Laboratory of Nuclear Installation Safety, Lithuanian Energy Institute, Breslaujos str. 3, LT-44403 Kaunas (Lithuania); Grybenas, Albertas [Laboratory of Materials Research and Testing, Lithuanian Energy Institute, Breslaujos str. 3, LT-44403 Kaunas (Lithuania); Karalevicius, Renatas [Laboratory of Nuclear Installation Safety, Lithuanian Energy Institute, Breslaujos str. 3, LT-44403 Kaunas (Lithuania); Makarevicius, Vidas [Laboratory of Materials Research and Testing, Lithuanian Energy Institute, Breslaujos str. 3, LT-44403 Kaunas (Lithuania); Rimkevicius, Sigitas; Uspuras, Eugenijus [Laboratory of Nuclear Installation Safety, Lithuanian Energy Institute, Breslaujos str. 3, LT-44403 Kaunas (Lithuania)
2013-07-15
Highlights: • Plastical deformation of the shock absorber. • Dynamic testing of the scaled shock absorber. • Dynamic simulation of the shock absorber using finite element method. • Strain-rate evaluation in dynamic analysis. • Variation of displacement, acceleration and velocity during dynamic impact. -- Abstract: The Ignalina Nuclear Power Plant (NPP) has two RBMK-1500 graphite moderated boiling water multi-channel reactors. The Ignalina NPP Unit 1 was shut down at the end of 2004 while Unit 2 has been in operation for over 5 years. After shutdown at the Unit 1 remained spent fuel assemblies with low burn-up depth. In order to reuse these assemblies in the reactor of Unit 2 a special set of equipment was developed. One of the most important items of this set is a container, which is used for the transportation of spent fuel assemblies between the reactors of Unit 1 and Unit 2. A special shock absorber was designed to avoid failure of fuel assemblies in case of hypothetical spent fuel assemblies drop accident during uploading/unloading of spent fuel assemblies to/from container. This shock absorber was examined using scaled experiments and finite element analysis. Static and dynamic investigations of the shock absorber were performed for the estimation and optimization of its geometrical parameters. The objective of this work is the estimation whether the proposed design of shock absorber can fulfil the stopping function of the spent fuel assemblies and is capable to withstand the dynamics load. Experimental testing of scaled shock absorber models and dynamic analytical investigations using the finite element code ABAQUS/Explicit were performed. The simulation model was verified by comparing the experimental and simulation results and it was concluded that the shock absorber is capable to withstand the dynamic load, i.e. successful force suppression function in case of accident.
Czech Academy of Sciences Publication Activity Database
Lukerchenko, Nikolay; Kvurt, Y.; Kharlamov, Alexander; Chára, Zdeněk; Vlasák, Pavel
2008-01-01
Roč. 56, č. 2 (2008), s. 88-94 ISSN 0042-790X R&D Projects: GA AV ČR IAA200600603 Institutional research plan: CEZ:AV0Z20600510 Keywords : drag force * drag torque * spherical particle * rotational movement * translational movement Subject RIV: DA - Hydrology ; Limnology
Energy Technology Data Exchange (ETDEWEB)
Goulier, J. [Institut de Combustion, Aérothermique, Réactivité et Environnement, CNRS-ICARE (France); Institut de Radioprotection et de Sûreté Nucléaire (IRSN) (France); Chaumeix, N., E-mail: chaumeix@cnrs-orleans.fr [Institut de Combustion, Aérothermique, Réactivité et Environnement, CNRS-ICARE (France); Halter, F. [Institut de Combustion, Aérothermique, Réactivité et Environnement, CNRS-ICARE (France); Meynet, N.; Bentaïb, A. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN) (France)
2017-02-15
The aim of this paper is to report new experimental results on the effect of turbulence on the propagation speed of hydrogen/air flames. To do so, a new experimental setup, called the spherical bomb, has been designed and built at CNRS-ICARE laboratory. With this new setup, the effect of a given and well-characterized turbulence intensity on the increase of hydrogen/air flame speed can be investigated. This new facility consists of a spherical vessel equipped (563 mm internal diameter) equipped with 8 motors which are linked to fans inside the bomb. Fan actuation induces the generation of a turbulent flow inside the vessel prior to any ignition. The spherical bomb is equipped with 4 quartz windows (200 mm optical diameter) that allow the use of a Particle Image Velocimetry diagnostic in order to characterize the turbulence level inside the bomb. The flame propagation was recorded using a high speed camera at 19,002 frames per second. These experiments were performed for lean to stoichiometric hydrogen/air mixtures (16–20% of H{sub 2} in air), initially at ambient temperature and pressure, and for a rotation speed from 1000 to 5000 rpm. The PIV measurements showed that a homogeneous and isotropic turbulence is created with a fluctuation speed that can reach 4 m/s at 5000 rpm.
Freeden, Willi; Schreiner, Michael
2018-01-01
This book presents, in a consistent and unified overview, results and developments in the field of today´s spherical sampling, particularly arising in mathematical geosciences. Although the book often refers to original contributions, the authors made them accessible to (graduate) students and scientists not only from mathematics but also from geosciences and geoengineering. Building a library of topics in spherical sampling theory it shows how advances in this theory lead to new discoveries in mathematical, geodetic, geophysical as well as other scientific branches like neuro-medicine. A must-to-read for everybody working in the area of spherical sampling.
Directory of Open Access Journals (Sweden)
Yaohua Chen
2017-03-01
Full Text Available We present our recent laser-plasmas instability (LPI comparison experiment at the SGIII laser facility between the spherical and cylindrical hohlraums. Three kinds of filling are considered: vacuum, gas-filling with or without a capsule inside. A spherical hohlraum of 3.6 mm in diameter, and a cylindrical hohlraum of 2.4 mm × 4.3 mm are used. The capsule diameter is 0.96 mm. A flat-top laser pulse with 3 ns duration and up to 92.73 kJ energy is used. The experiment has shown that the LPI level in the spherical hohlraum is close to that of the outer beam in the cylindrical hohlraum, while much lower than that of the inner beam. The experiment is further simulated by using our 2-dimensional radiation hydrodynamic code LARED-Integration, and the laser back-scattering fraction and the stimulated Raman scatter (SRS spectrum are post-processed by the high efficiency code of laser interaction with plasmas HLIP. According to the simulation, the plasma waves are strongly damped and the SRS is mainly developed at the plasma conditions of electron density from 0.08 nc to 0.1 nc and electron temperature from 1.5 keV to 2.0 keV inside the hohlraums. However, obvious differences between the simulation and experiment are found, such as that the SRS back-scattering is underestimated, and the numerical SRS spectrum peaks at a larger wavelength and at a later time than the data. These differences indicate that the development of a 3D radiation hydrodynamic code, with more accurate physics models, is mandatory for spherical hohlraum study.
Irradiation performance of experimental fast reactor 'JOYO' MK-1 driver fuel assemblies
International Nuclear Information System (INIS)
Itaki, Toshiyuki; Kono, Keiichi; Tachi, Hirokatsu; Yamanouchi, Sadamu; Yuhara, Shunichi; Shibahara, Itaru
1985-01-01
The experimental fast reactor ''JOYO'' completed it's breeder core (MK-I) operation in January 1982. The MK-I driver fuel assemblies were removed from the core sequencially in order of burnup increase and have been under postirradiation examination (PIE). The PIE has almost been completed for 30 assemblies including the highest burnup assemblies of 48,000 MWD/MTM. It has been confirmed that all fuel assemblies have exhibited satisfactory performance without detrimental assembly deformation or without any indications of fuel pin breach. The irradiation conditions of the MK-I core were somewhat more moderate than those conditions envisioned for prototypic reactor. However the results of the examination revealed the typical irradiation behavior of LMFBR fuels, although such characteristics were benign as compared with those anticipated in high burnup fuels. Systematic performance data have been accumulated through the fuel fabrication, irradiation and postirradiation examination processes. Based on these data, the MK-I fuel designing and fabrication techniques were totally confirmed. This technical experience and the associated insight into irradiation behavior have established a milestone to the next step of fast reactor fuel development. (author)
Cai, Chunhua; Zhang, Liangshun; Lin, Jiaping; Wang, Liquan
2008-10-09
We investigated, both experimentally and theoretically, the self-assembly behaviors of pH- and thermosensitive poly(L-glutamic acid)- b-poly(propylene oxide)-b-poly(L-glutamic acid) (PLGA-b-PPO-b-PLGA) triblock copolymers in aqueous solution by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), circular dichroism (CD), and self-consistent field theory (SCFT) simulations. Vesicles were observed when the hydrophilic PLGA block length is shorter or the pH value of solution is lower. The vesicles were found to transform to spherical micelles when the PLGA block length increases or its conformation changes from helix to coil with increasing the pH value. In addition, increasing temperature gives rise to a decrease in the size of aggregates, which is related to the dehydration of the PPO segments at higher temperatures. The SCFT simulation results show that the vesicles transform to the spherical micelles with increasing the fraction or statistical length of A block in model ABA triblock copolymer, which corresponds to the increase in the PLGA length or its conformation change from helix to coil in experiments, respectively. The SCFT calculations also provide chain distribution information in the aggregates. On the basis of both experimental and SCFT results, the mechanism of the structure change of the PLGA- b-PPO- b-PLGA aggregates was proposed.
Cohen, Taco S.; Geiger, Mario; Koehler, Jonas; Welling, Max
2018-01-01
Convolutional Neural Networks (CNNs) have become the method of choice for learning problems involving 2D planar images. However, a number of problems of recent interest have created a demand for models that can analyze spherical images. Examples include omnidirectional vision for drones, robots, and autonomous cars, molecular regression problems, and global weather and climate modelling. A naive application of convolutional networks to a planar projection of the spherical signal is destined t...
Experimental study of flow induced vibration of the planar fuel assembly
International Nuclear Information System (INIS)
Wang Jinhua; Bo Hanliang; Jiang Shengyao; Jia Haijun; Zheng Wenxiang; Min Gang; Qu Xinxing
2005-01-01
The paper studied the flow-induced vibration of the planar fuel assembly under scour of coolant through experiments, the study includes: the characteristics of the inherent vibration, the response to the flow-induced vibration in rating condition and the confirmation of the critical flow velocity's scope of the flow flexible instability. The velocity distributions in different flow channels formed by fuel plates in the assembly were measured, and the velocity distribution in the same flow channel was also measured. The experimental conclusions includes: the inherent vibration frequency of the planar fuel assembly is different for a little in each direction. The damp ratio corresponding to the assembly each rank's inherent frequency is small, and the damp ratio decreased with the increase of the corresponding inherent frequency. The velocity in different flow channels decreased from outside to inside, and the velocity in the middle channel was the least; the velocity in the same channel decreased from inside to outside, and the velocity in the middle position was the most. The vibration swing of the fuel assembly was small at rating condition, and the vibration swing of the fuel plates was larger than side plates. The vibration of the fuel assembly increased with the increase of the velocity, the vibration of the middle fuel plate were larger than the border fuel plate, and the vibration of the border fuel plate was larger than the side plate. The large scale vibration of the flow flexible instability didn't occur in the velocity scope of 0-18.8 m/s in the experiment, so the critical flow velocity of the flow flexible instability was not in the flow velocity scope of the experiment. (authors)
Analytical and experimental analysis of YALINA-Booster and YALINA-Thermal assemblies
International Nuclear Information System (INIS)
Kiyavitskaya, H.; Bournos, V.; Mazanik, S.; Khilmanovich, A.; Martsinkevich, B.; Routkovskaya, Ch.; Edchik, I.; Fokov, Y.; Sadovich, S.; Fedorenko, A.; Gohar, Y.; Talamo, A.
2010-01-01
Full text: Accelerator Driven Systems (ADS) may play an important role in future nuclear fuel cycles to reduce the longterm radiotoxicity and volume of spent nuclear fuel. It is proposed that ADS will produce energy and incinerate radioactive waste. This technology was called Accelerator Driven Transmutation Technology (ADTT). The most important problems of this technology are monitoring of a reactivity level in on-line regime, a choice of neutron spectrum appropriate for incineration of Minor Actinides (MA) and transmutation of Long Lived Fission Products (LLFP) and etc. Before the designing and construction of an installation it is necessary to carry out R and D to validate codes, nuclear data libraries and other instrumentations. The YALINA facility is designed to study the ADS physics and to investigate the transmutation reaction rates of MA and LLFP. The main objective of the YALINA benchmark is to compare the results from different calculation methods with each other and experimental data. The benchmark is based on the current YALINA facility configuration, which provides the opportunity to verify the prediction capability of the different methods. The experimental data have been obtained in the frame of the ISTC Projects B1341 'Analytical and experimental evaluation of the possibility to create a universal volume source of neutrons in the sub-critical booster assembly with low enrichment uranium fuel driven by a neutron generator' and B1732P 'Analytical and experimental evaluating the possibility of creation of universal volume source of neutrons in the sub-critical booster assembly with low enriched uranium fuel driven by the neutron generator'. In this paper a comparison of the experimental and calculated data obtained for YALINA-Booster subcritical assembly with a fuel of different enrichment and for YALINA-Thermal with a different number of control rods (216, 245 and 280) will be done.
STS-61B Astronauts Ross and Spring Work on Experimental Assembly of Structures in Extravehicular
1985-01-01
The crew assigned to the STS-61B mission included Bryan D. O'Conner, pilot; Brewster H. Shaw, commander; Charles D. Walker, payload specialist; mission specialists Jerry L. Ross, Mary L. Cleave, and Sherwood C. Spring; and Rodolpho Neri Vela, payload specialist. Launched aboard the Space Shuttle Atlantis November 28, 1985 at 7:29:00 pm (EST), the STS-61B mission's primary payload included three communications satellites: MORELOS-B (Mexico); AUSSAT-2 (Australia); and SATCOM KU-2 (RCA Americom). Two experiments were conducted to test assembling erectable structures in space: EASE (Experimental Assembly of Structures in Extravehicular Activity), and ACCESS (Assembly Concept for Construction of Erectable Space Structure). In a joint venture between NASA/Langley Research Center in Hampton, Virginia, and the Marshall Space Flight Center (MSFC), EASE and ACCESS were developed and demonstrated at MSFC's Neutral Buoyancy Simulator (NBS). This STS-61B onboard photo depicts astronauts Ross and Spring working on EASE. The primary objective of these experiments was to test the structural assembly concepts for suitability as the framework for larger space structures and to identify ways to improve the productivity of space construction.
Row of fuel assemblies analysis under seismic loading: Modelling and experimental validation
International Nuclear Information System (INIS)
Ricciardi, Guillaume; Bellizzi, Sergio; Collard, Bruno; Cochelin, Bruno
2009-01-01
The aim of this study was to develop a numerical model for predicting the impact behaviour at fuel assembly level of a whole reactor core under seismic loading conditions. This model was based on a porous medium approach accounting for the dynamics of both the fluid and structure, which interact. The fluid is studied in the whole reactor core domain and each fuel assembly is modelled in the form of a deformable porous medium with a nonlinear constitutive law. The contact between fuel assemblies is modelled in the form of elastic stops, so that the impact forces can be assessed. Simulations were performed to predict the dynamics of a six fuel assemblies row immersed in stagnant water and the whole apparatus was placed on a shaking table mimicking seismic loading conditions. The maximum values of the impact forces predicted by the model were in good agreement with the experimental data. A Proper Orthogonal Decomposition analysis was performed on the numerical data to analyse the mechanical behaviour of the fluid and structure more closely.
Energy Technology Data Exchange (ETDEWEB)
Mays, Brian [AREVA Federal Services, Lynchburg, VA (United States); Jackson, R. Brian [TerraPower, Bellevue, WA (United States)
2017-03-08
The project, Toward a Longer Life Core: Thermal Hydraulic CFD Simulations and Experimental Investigation of Deformed Fuel Assemblies, DOE Project code DE-NE0008321, was a verification and validation project for flow and heat transfer through wire wrapped simulated liquid metal fuel assemblies that included both experiments and computational fluid dynamics simulations of those experiments. This project was a two year collaboration between AREVA, TerraPower, Argonne National Laboratory and Texas A&M University. Experiments were performed by AREVA and Texas A&M University. Numerical simulations of these experiments were performed by TerraPower and Argonne National Lab. Project management was performed by AREVA Federal Services. The first of a kind project resulted in the production of both local point temperature measurements and local flow mixing experiment data paired with numerical simulation benchmarking of the experiments. The project experiments included the largest wire-wrapped pin assembly Mass Index of Refraction (MIR) experiment in the world, the first known wire-wrapped assembly experiment with deformed duct geometries and the largest numerical simulations ever produced for wire-wrapped bundles.
International Nuclear Information System (INIS)
Sinman, S.; Sinman, A.
2003-01-01
The aim of this study is to identify the physical basis of the alternative self-organization mechanism that exists on the STPC-EX machine and to determine complementary features with respect to present compact toroid concepts. In the STPC-EX machine, there exist two solenoids placed inside the central passive floating conductive hollow rod and externally onto flux conserver. These are in a passive state and they do not have an important role in the self-created spherical tokamak plasma (SCSTP) in the STPC-EX machine. In this study, conventional diagnostic tools are used and for photographic recording, the method of open shutter integrated post-fogging is chosen. Two annular coaxial plasma current sheets, one within the other in the same direction, are created and flow on the surface of the central conductive hollow rod. Consequently, the spherical tokamak is configured by a new creation mechanism called the dual-axial z-pinch. High betas of 0.4-0.6 and aspect ratios of up to 1.25 can be obtained. (author)
Structure and experimental program for SNEAK 12 - an assembly for fast breeder safety experiments
International Nuclear Information System (INIS)
Helm, F.
1979-01-01
The critical assembly SNEAK 12 and its foreseen experimental program have the main purpose to check the validity of neutron physics calculational methods used in the analysis of accidental situations of fast breeder reactors. In the investigation of accidental courses configurations have to be considered, which are caused by assembly deformation and meltdown and which are characterized by irregular fuel and structural material arrangements with cavities and empty channels. The reactivity differences between the unperturbed core and a series of perturbed configurations have to be determined. The individual configurations have to be chosen in such a way, that the calculational methods for the different aspects of the accident sequence (formation of cavities and channels, relocation of fissile and fertile material and steel) can be tested one by one. Two different cores are foreseen: SNEAK 12A as a one-zone core with enriched uranium fuel and SNEAK 12B with a central test zone with plutonium-uranium mixed-oxide fuel surrounded by a driver zone of enriched uranium. The report describes these cores and their assemblies, and the experimental program is outlined
Experimental investigation of control absorber blade effects in a modern 10x10 BWR assembly
Energy Technology Data Exchange (ETDEWEB)
Jatuff, F.; Grimm, P.; Murphy, M.; Luethi, A.; Seiler, R.; Joneja, O.; Meister, A.; Geemert, R. van; Brogli, R.; Chawla, R. [Paul Scherrer Inst., CH-5232 Villigen PSI (Switzerland); Williams, T. [EGL Laufenburg (Switzerland); Helmersson, S. [Westinghouse Atom (Sweden)
2001-03-01
The accurate estimation of reactor physics parameters related to the presence of cruciform absorber blades. In Boiling Water Reactors (BWR) is important for safety assessment, and for achieving a flexible operation during the cycle. Characteristics which are affected strongly include the power distribution for controlled core regions and its impact on linear heat generation rate margins, as well as the build-up of plutonium, and its influence on core excess reactivity and the reactivity worth of the shutdown system. PSI and the Swiss Nuclear Utilities (UAK) are conducting an experimental reactor physics programme related to modern Light Water Reactor (LWR) fuel assemblies, as employed in the Swiss nuclear power plants: the so-called. LWR-PROTEUS Phase I project. A significant part of this project has been devoted to the characterization of highly heterogeneous BWR fuel elements in the presence of absorber blades. The paper presents typical results for the performance of modern lattice codes in the estimation of controlled assembly reaction rate distributions, the sensitivity to the geometrical and material characterization, and a preliminary comparison of reflected-test-zone calculations with experimental reaction rate distributions measured in a Westinghouse SVEA-96+ assembly under full-density water moderation conditions in the presence of Westinghouse boron-carbide absorber blades. (author)
Experimental investigation of control absorber blade effects in a modern 10x10 BWR assembly
International Nuclear Information System (INIS)
Jatuff, F.; Grimm, P.; Murphy, M.; Luethi, A.; Seiler, R.; Joneja, O.; Meister, A.; Geemert, R. van; Brogli, R.; Chawla, R.; Williams, T.; Helmersson, S.
2001-01-01
The accurate estimation of reactor physics parameters related to the presence of cruciform absorber blades. In Boiling Water Reactors (BWR) is important for safety assessment, and for achieving a flexible operation during the cycle. Characteristics which are affected strongly include the power distribution for controlled core regions and its impact on linear heat generation rate margins, as well as the build-up of plutonium, and its influence on core excess reactivity and the reactivity worth of the shutdown system. PSI and the Swiss Nuclear Utilities (UAK) are conducting an experimental reactor physics programme related to modern Light Water Reactor (LWR) fuel assemblies, as employed in the Swiss nuclear power plants: the so-called. LWR-PROTEUS Phase I project. A significant part of this project has been devoted to the characterization of highly heterogeneous BWR fuel elements in the presence of absorber blades. The paper presents typical results for the performance of modern lattice codes in the estimation of controlled assembly reaction rate distributions, the sensitivity to the geometrical and material characterization, and a preliminary comparison of reflected-test-zone calculations with experimental reaction rate distributions measured in a Westinghouse SVEA-96+ assembly under full-density water moderation conditions in the presence of Westinghouse boron-carbide absorber blades. (author)
Energy Technology Data Exchange (ETDEWEB)
Nam, Kyung Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Sang Nyung [Kyunghee Univ., Gyeonggi-do (Korea, Republic of)
2017-06-15
After the Fukushima accident, increasing interest has been raised in passive safety systems that maintain the integrity of the containment building. To improve the reliability and safety of nuclear power plants, long-term passive cooling concepts have been developed for advanced reactors. In a previous study, the proposed design was based on an ordinary cylindrical Two-Phase Closed Thermosyphon (TPCT). The exact assembly size and number of TPCTs should be elaborated upon through accurate calculations based on experiments. While the ultimate goal is to propose an effective MPHP design for the PCCS and experimentally verify its performance, a TPCT assembly that was manufactured based on the conceptual design in this paper was tested.
Experimental studies of flow induced vibrations of the fuel assembly for the PEC reactor
International Nuclear Information System (INIS)
Pitimada, D.; Presaghi, M.; Tampone, O.; Cesari, F.
1977-01-01
The vibration behaviour of an assembly of seven mock-up fuel bundles of PEC reactor has been investigated. The assembly was excited by a parallel flow of water simulating sodium. The motion of the group (or of a single bundle in the group) has been measured in transverse sections detecting two orthogonal components of displacement. During the experiences the following parameters were varied: bundle foot and pads restraints, flow rate condition, coolant flow outlet conditions at the head of fuel bundles. Experimental data were processed in order to obtain: trajectories of three points of fuel bundle axis, power density spectra of measured vibration amplitudes, correlations between coolant flow rate and vibration amplitude R.M.S. (author)
Energy Technology Data Exchange (ETDEWEB)
Raman, R.; Jarboe, T. R.; Nelson, B. A. [University of Washington, Seattle, Washington 98195 (United States); Mueller, D.; Bell, M. G.; Gerhardt, S.; LeBlanc, B.; Menard, J.; Ono, M.; Roquemore, L. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Soukhanovskii, V. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)
2011-09-15
Discharges initiated by transient coaxial helicity injection in National Spherical Torus Experiment have attained peak toroidal plasma currents up to 300 kA. When induction from the central solenoid is then applied, these discharges develop up to 300 kA additional current compared to discharges initiated by induction only. CHI initiated discharges in NSTX have achieved 1 MA of plasma current using only 258 mWb of solenoid flux whereas standard induction-only discharges require about 50% more solenoid flux to reach 1 MA. In addition, the CHI-initiated discharge has lower plasma density and a low normalized internal plasma inductance of 0.35, as needed for achieving advanced scenarios in NSTX.
Calculated and experimental research of WWER-1000 assembly vibration and fretting damage
International Nuclear Information System (INIS)
Drozdov, Y.; Afanasyev, A.; Makarov, V.; Tutnov, A.; Tutnov, A.; Alekseev, E.
2008-01-01
The report covers the methods and results of the latest analytical and experimental studies of fretting corrosion and natural vibrations of a WWER-1000 reactor fuel assemblies (FA). The process of fretting-corrosion was investigated using a multi-specimen facility that simulated fragments of fuel rod-to-spacer grid and lower support grid mating units. A computational model was developed for vibrations in the mechanical system of a fuel rod fragment and a spacer grid fragment. A calculational and experimental modal analysis of a FA was performed. Natural frequencies, modes and decrements of FA vibrations were determined and a satisfactory coincidence of analytical and experimental results was obtained. The assessment of fretting-corrosion process dynamics was made and its dependences on operational factors were obtained. (authors)
International Nuclear Information System (INIS)
Chandrasekaran, P.; Cheralathan, M.; Velraj, R.
2015-01-01
The present study aims to investigate the solidification characteristics of water, as the PCM (phase change material), due to the effect of fill volume of PCM in a spherical capsule. The experiments were conducted with the spherical capsule, filling it with water of 80, 85, 90, 92 and 95 percentage of its full volume and immersing it in a constant temperature bath maintained at various temperatures. It was observed that the increase in fill volume had a significant influence in reducing the degree of supercooling and it was eliminated with 95% fill volume. Further, the increase in fill volume had a considerable effect in advancing the commencement of solidification. Increasing the temperature potential enhanced the heat flux during the solidification of first 50% of PCM mass and its effect was more pronounced at higher fill volumes. The heat flux was increased several fold particularly at 95% fill volume making it highly suitable for applications that demand large cooling load in a short duration. Hence the proper selection of fill volume and temperature driving potential is essential to achieve overall energy efficiency while designing the CTES (cool thermal energy storage) system. - Highlights: • Supercooling was eliminated with 95% fill volume at all surrounding bath temperature. • The effect of higher fill volume is more pronounced with higher temperature potential. • 50% mass is solidified in 10% of solidification duration with 95% fill volume at −12 °C. • Several fold increase in heat flux is achieved with 95% fill volume at −12 °C. • Combination of fill volume and temperature potential is essential for good design.
Deshkar, Sanjeevani Shekhar; Borde, Govind R; Kale, Rupali N; Waghmare, Balasaheb A; Thomas, Asha Biju
2017-01-01
Spherical agglomeration is one of the novel techniques for improvement of flow and dissolution properties of drugs. Cilostazol is a biopharmaceutics classification system Class II drug with poor solubility resulting in limited bioavailability. The present study aims at improving the solubility and dissolution of cilostazol by crystallo-co-agglomeration technique. Cilostazol agglomerates were prepared using various polymers with varying concentration of hydroxypropyl methylcellulose E 50 (HPMC E50), polyvinyl pyrrolidone K30 (PVP K30), and polyethylene glycol 6000. The influence of polymer concentration on spherical agglomerate formation was studied by 3 2 factorial design. Cilostazol agglomerates were evaluated for percent yield, mean particle size, drug content, aqueous solubility, and in vitro dissolution and further characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The agglomeration process resulted in optimized formulation, F3 with mean agglomerate size of 210.0 ± 0.56 μm, excellent flow properties, approximately 15-fold increase in solubility than pure cilostazol and complete drug release in 60 min. Process yield, agglomerate size, and drug release were affected by amount of PVP K 30 and HPMC E50. The presence of drug microcrystal was confirmed by SEM, whereas FTIR study indicated no chemical change. Increase in drug solubility was attributed to change of crystalline drug to amorphous form that is evident in DSC and XRD. Crystallo-co-agglomeration can be adopted as an important approach for increasing the solubility and dissolution of poorly soluble drug.
International Nuclear Information System (INIS)
Fiksel, G.; Hu, S. X.; Goncharov, V. A.; Meyerhofer, D. D.; Sangster, T. C.; Yaakobi, B.; Bonino, M. J.; Jungquist, R.; Smalyuk, V. A.
2012-01-01
The effect of medium-Z doping of plastic ablators on laser imprinting and Rayleigh–Taylor (RT) instability growth was studied using spherical direct-drive implosions on the OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1977)]. The targets were spherical plastic (CH) shells, with an outer diameter of 860 μm and a thickness of 22 μm, volume doped with a varied concentration of Si (4.3% and 7.4%) and Ge (3.9%). The targets were imploded with 48 beams with a low-adiabat, triple-picket laser shape pulse with a peak intensity of 4×10 14 W/cm 2 , and a pulse duration of 2.5 ns. The shells were x-ray radiographed through a 400 -μm opening in the side of the target. The results show that volumetric impurity doping strongly reduces the shell density modulation and the instability growth rate. The amplitude of the initial imprint is reduced by a factor of 2.5 ± 0.5 for CH[4.3% Si] targets and by a factor of 3 ± 0.5 for CH[7.4% Si] and CH[3.9% Ge] targets. At the end of the acceleration phase, the reduction factor becomes 3 ± 0.5 and 5 ± 0.5, correspondingly. The RT instability growth rate in doped targets is reduced by a factor of 1.5 compared to undoped ones. Simulations using the two-dimensional, radiation-hydrodynamics code draco show good agreement with the measurements.
Physics study of D-D/D-T neutron driven experimental subcritical assembly
International Nuclear Information System (INIS)
Sinha, Amar
2015-01-01
An experimental program to design and study external source driven subcritical assembly has been initiated at BARC. This program is aimed at understanding neutronic characteristics of accelerator driven system at low power level. In this series, a zero-power, sub-critical assembly driven by a D-D/D-T neutron generator has been developed. This system is modular in design and it is first in the series of subcritical assemblies being designed. The subcritical core consists of natural uranium fuel with high density polyethylene as moderator and beryllium oxide as reflector. The subcritical core is coupled to Purnima Neutron Generator. Preliminary experiments have been carried out for spatial flux measurement and reactivity estimation using pulsed neutron source (PNS) techniques. Further experiments are being planned to measure the reactivity and other kinetic parameters using noise methods. This facility would also be used for carrying out studies on effect of source importance and measurement of source multiplication factor k s and external neutron source efficiency φ* in great details. Some experiments with D-D and D-T neutrons have been presented. (author)
Gravitational sedimentation of cloud of solid spherical particles at small Reynolds numbers
Directory of Open Access Journals (Sweden)
Arkhipov Vladimir
2015-01-01
Full Text Available The experimental results of study of gravitational sedimentation of highly-concentrated systems of solid spherical particles at small Reynolds numbers Re<1 are presented. Empirical equation for drag coefficient of the particle assembly has been obtained. The influence of initial particle concentration in the cloud on its dynamics and velocity has been analysed.
Long-term changes in community assembly, resistance, and resilience following experimental floods.
Robinson, Christopher T
2012-10-01
This study examined the long-term changes in community assembly, resistance, and resilience of macroinvertebrates following 10 years of experimental floods in a flow regulated river. Physico-chemistry, macroinvertebrates, and periphyton biomass were monitored before and sequentially after each of 22 floods, and drift/seston was collected during six separate floods over the study period. The floods reduced the density and taxon richness of macroinvertebrates, and a nonmetric dimensional scaling (NMDS) analysis distinguished temporal shifts in community assembly. Resistance (measured as the relative lack of loss in density) tofloods varied among taxa, and the abundance of resistant taxa was related to the temporal changes in community assembly. Community resistance was inversely related to flood magnitude with all larger floods (> 25 m3/s, > 16-fold over baseflow) reducing densities by > 75% regardless of flood year, whereas smaller floods (floods. No relationship was found between flood magnitude and the relative loss in periphyton biomass. Resilience was defined as the recovery slope (positive slope of a parameter with time following each flood) and was unrelated to shifts in community assembly or resistance. Macroinvertebrate drift and seston demonstrated hysteresis (i.e., a temporal response in parameter quantity with change in discharge) during each flood, although larger floods typically had two peaks in both parameters. The first peak was a response to the initial increases in flow, whereas the second peak was associated with streambed disturbance (substrate mobility) and side-slope failure causing increased scour. Drift density was 3-9 times greater and that of seston 3-30 times greater during larger floods than smaller floods. These results demonstrate temporal shifts in macroinvertebrate community assembly toward a pre-dam assemblage following sequential floods in this flow regulated river, thus confirming the ecological role of habitat filtering in
International Nuclear Information System (INIS)
Bosser, M.; Vagner, J.
1987-01-01
The fatigue behavior of a bolted assembly can be analysed, either by fatigue tests, or by computing the stress variations and using a fatigue curve. This paper presents the fatigue analysis of a stud-bolt and stud-flange of a steam generator manway carried out with the two methods. The experimental analysis is performed for various levels of load, according to the recommandations of the ASME code section III appendix II. The numerical analysis of the stresses is based on the results of a finite element analysis performed with the program SYSTUS. The maximum stresses are obtained in the first bolt threads. In using these stresses, the allowable number of cycles for each level of loading analysed, is obtained from fatigue curves, as defined in appendix I section III of the ASME code. The analysis underlines that, for each level of load the purely numerical approach is highly conservative, compared to the experimental approach. (orig.)
Experimental study of pressure drops through LOCA-generated debris deposited on a fuel assembly
Energy Technology Data Exchange (ETDEWEB)
Suh, Jeong Kwan, E-mail: jksuh@khnp.co.kr [KHNP Central Research Institute, 1312-70 Yuseong-daero, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Kim, Jae Won; Kwon, Sun Guk; Lee, Jae Yong [KHNP Central Research Institute, 1312-70 Yuseong-daero, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Cho, Hyoung Kyu; Park, Goon Cherl [Department of Nuclear Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)
2015-08-15
Highlights: • In-vessel downstream effect tests were performed in the presence of LOCA-generated debris. • Available driving heads under each LOCA scenario were verified using experimental data. • Fibrous debris was prepared to satisfy the length distribution obtained from the bypass test. • Limiting test conditions were identified through sensitivity studies. - Abstract: Under post loss-of-coolant accident (LOCA) conditions, it is postulated that debris can be generated and transported to the containment sump strainer. Some of the debris may pass through the strainer and could challenge the long-term core cooling capability of the plant. To address this safety issue, in-vessel downstream effect tests for the advanced power reactor (APR) 1400 were performed. Fibrous debris is the most crucial material in terms of causing pressure drops, and was prepared in this study to satisfy the fiber length distribution obtained through a strainer bypass test. Sensitivity studies on pressure drops through LOCA-generated debris deposited on a fuel assembly were performed to evaluate the effects of water chemistry and fiber length distribution. The pressure drops with debris laden pure water were substantially less than those with debris laden ordinary tap water. The experiment with fiber length distribution suggested by WCAP-16793 showed lower pressure drops than those with the APR1400 specific fiber length distribution. All the experimental results showed that the pressure drops in the mock-up fuel assembly were less than the available driving head at each LOCA scenario.
International Nuclear Information System (INIS)
Onozuka, M.; Takeda, N.; Nakahira, M.; Shimizu, K.; Nakamura, T.
2003-01-01
The most recent assessment method to evaluate the dynamic behavior of the International Thermonuclear Experimental Reactor (ITER) tokamak assembly is outlined. Three experimental models, including a 1/5.8-scale tokamak model, have been considered to validate the numerical analysis methods for dynamic events, particularly seismic ones. The experimental model has been evaluated by numerical calculations and the results are presented. In the calculations, equivalent linearization has been applied for the non-linear characteristics of the support flange connection, caused by the effects of the bolt-fastening and the friction between the flanges. The detailed connecting conditions for the support flanges have been developed and validated for the analysis. Using the conditions, the eigen-mode analysis has shown that the first and second eigen-mode are horizontal vibration modes with the natural frequency of 39 Hz, while the vertical vibration mode is the fourth mode with the natural frequency of 86 Hz. Dynamic analysis for seismic events has shown the maximum acceleration of approximately twofold larger than that of the applied acceleration, and the maximum stress of 104 MPa found in the flange connecting bolt. These values will be examined comparing with experimental results in order to validate the analysis methods
Energy Technology Data Exchange (ETDEWEB)
Onozuka, M. E-mail: masanori_onozuka@mhi.co.jp; Takeda, N.; Nakahira, M.; Shimizu, K.; Nakamura, T
2003-09-01
The most recent assessment method to evaluate the dynamic behavior of the International Thermonuclear Experimental Reactor (ITER) tokamak assembly is outlined. Three experimental models, including a 1/5.8-scale tokamak model, have been considered to validate the numerical analysis methods for dynamic events, particularly seismic ones. The experimental model has been evaluated by numerical calculations and the results are presented. In the calculations, equivalent linearization has been applied for the non-linear characteristics of the support flange connection, caused by the effects of the bolt-fastening and the friction between the flanges. The detailed connecting conditions for the support flanges have been developed and validated for the analysis. Using the conditions, the eigen-mode analysis has shown that the first and second eigen-mode are horizontal vibration modes with the natural frequency of 39 Hz, while the vertical vibration mode is the fourth mode with the natural frequency of 86 Hz. Dynamic analysis for seismic events has shown the maximum acceleration of approximately twofold larger than that of the applied acceleration, and the maximum stress of 104 MPa found in the flange connecting bolt. These values will be examined comparing with experimental results in order to validate the analysis methods.
Directory of Open Access Journals (Sweden)
Luay Hashem Abbud
2016-12-01
Full Text Available In this study, a response of hybrid composite laminate woven fiber Kevlar29 – Al2O3 Powder/ Epoxy subjected to high velocity impact loading is presented. The energy absorbed due to impact of small rigid projectile on composite materials targets is determined experimentally. The energy absorbed due to impact of hemispherical projectiles on the developed composite laminates is investigated. The results revealed the maximum ballistic limit at impact velocity is found to be 390.87 ± 6 m/s for an the 18 mm target thickness. The ballistic limit velocity predictions are based on the theoretical method presented from another article. The initial velocity and residual velocity results showed good is agreement compared with the predicted results of Ipson and Recht equations. With 5.4 % of accuracy based on the experimental value for the theoretical model for ballistic limit velocity.
Telles, J. E.; de Souza, R. E.; Penereiro, J. C.
1990-11-01
RESUMEN. Presentamos fotometria fotografica de 8 objetos y espectrosco- pla para 3 galaxias, las cuales son buenos candidatos para galaxias esfericas. Los resultados fotometricos se presentan en la forma de iso- fotas y de perfiles radiales promedlo, de los cuales se derivan para- metros estructurales. Estas observaciones combinadas con parametros di- namicos obtenidos de observaciones espectrosc6picas, son consistentes con el plano fundamental derivado por Djorgovski y Davis (1987). ABSTRACT. We present photographic surface photometry for 8 objects and spectroscopy for 3 galaxies which are good candidates for spherical galaxies. Photometric results are presented in the form of isophotes and mean radial profiles from which we derived structural parameters. These observations combined with dynamical parameters obtained from spectroscopic observations are consistent with the fundamental plane derived by Djorgovski and Davis (1987). Keq wo : CALAXIES-ELLIPTICAL
Dabby, Nadine L.
Computer science and electrical engineering have been the great success story of the twentieth century. The neat modularity and mapping of a language onto circuits has led to robots on Mars, desktop computers and smartphones. But these devices are not yet able to do some of the things that life takes for granted: repair a scratch, reproduce, regenerate, or grow exponentially fast--all while remaining functional. This thesis explores and develops algorithms, molecular implementations, and theoretical proofs in the context of "active self-assembly" of molecular systems. The long-term vision of active self-assembly is the theoretical and physical implementation of materials that are composed of reconfigurable units with the programmability and adaptability of biology's numerous molecular machines. En route to this goal, we must first find a way to overcome the memory limitations of molecular systems, and to discover the limits of complexity that can be achieved with individual molecules. One of the main thrusts in molecular programming is to use computer science as a tool for figuring out what can be achieved. While molecular systems that are Turing-complete have been demonstrated [Winfree, 1996], these systems still cannot achieve some of the feats biology has achieved. One might think that because a system is Turing-complete, capable of computing "anything," that it can do any arbitrary task. But while it can simulate any digital computational problem, there are many behaviors that are not "computations" in a classical sense, and cannot be directly implemented. Examples include exponential growth and molecular motion relative to a surface. Passive self-assembly systems cannot implement these behaviors because (a) molecular motion relative to a surface requires a source of fuel that is external to the system, and (b) passive systems are too slow to assemble exponentially-fast-growing structures. We call these behaviors "energetically incomplete" programmable
Untangling dopamine-adenosine receptor-receptor assembly in experimental parkinsonism in rats
Directory of Open Access Journals (Sweden)
Víctor Fernández-Dueñas
2015-01-01
Full Text Available Parkinson’s disease (PD is a dopaminergic-related pathology in which functioning of the basal ganglia is altered. It has been postulated that a direct receptor-receptor interaction – i.e. of dopamine D2 receptor (D2R with adenosine A2A receptor (A2AR (forming D2R-A2AR oligomers – finely regulates this brain area. Accordingly, elucidating whether the pathology prompts changes to these complexes could provide valuable information for the design of new PD therapies. Here, we first resolved a long-standing question concerning whether D2R-A2AR assembly occurs in native tissue: by means of different complementary experimental approaches (i.e. immunoelectron microscopy, proximity ligation assay and TR-FRET, we unambiguously identified native D2R-A2AR oligomers in rat striatum. Subsequently, we determined that, under pathological conditions (i.e. in a rat PD model, D2R-A2AR interaction was impaired. Collectively, these results provide definitive evidence for alteration of native D2R-A2AR oligomers in experimental parkinsonism, thus conferring the rationale for appropriate oligomer-based PD treatments.
International Nuclear Information System (INIS)
Nakano, M.; Iijima, S.; Shirakata, K.; Hirota, J.
1980-01-01
To investigate physics properties of the heterogeneous LMFBR core and to examine the reliability of the current data and method for heterogeneous core configuration, an experimental study has been made on FCA VII-3 assemblies which have an internal blanket (IB) at midplane of the cylindrical core. Systematic experiments were carried out on the heterogeneous cores whose IBs were different in composition and thickness. A homogeneous core was also built to compare the results with those obtained on the heterogeneous cores. The sodium-void worth is not sensitive to the composition of IB. The positive void worth in the core of the 40 cm IB is lowered by about 40% compared with that in the homogeneous core. The analysis was made using the JAERI-Fast Set Version II and the diffusion code CITATION. Directional diffusion coefficients were used to take account of the axial streaming. To evaluate transport effects, the S 4 calculation was made. Comparison between the calculated and experimental results reveals the following: ksub(eff) and Pu worth in the core are not well predicted for the heterogeneous core, although they are represented satisfactorily for the homogeneous core. Reaction rates sensitive to the low-energy neutron are underestimated in the IB when they are normalized in the core. Sodium-void worths are fairly well predicted. However, the positive void worth in the heterogeneous core is underestimated, while that in the homogeneous core is overestimated. (author)
International Nuclear Information System (INIS)
Khafizov, R.R.; Poplavskij, V.M.; Rachkov, V.I.; Sorokin, A.P.; Ashurko, Yu.M.; Volkov, A.V.; Ivanov, E.F.; Privezentsev, V.V.
2015-01-01
The experimental facility is built up and investigation of heat exchange during sodium boiling in simulated fast reactor core assembly in conditions of natural and forced circulation with sodium plenum and upper end shield model are conducted. It is shown that in the presence of sodium plenum there is possibility to provide long-term cooling of fuel assembly when heat flux density on the surface of fuel element simulator up to 140 and 170 kW/m 2 in conditions of natural and forced circulation, respectively. The obtained data is used for improving calculational model of sodium boiling process in fuel assembly and calculational code COREMELT verification. It is pointed out that heat transfer coefficients in the case of liquid metal boiling in fuel assemblies are slightly over the ones in the case of liquid metals boiling in pipes and pool boiling [ru
International Nuclear Information System (INIS)
Berg, S.; Semmes, P.B.; Nazarewicz, W.
1997-01-01
Various theoretical approaches to proton emission from spherical nuclei are investigated, and it is found that all the methods employed give very similar results. The calculated decay widths are found to be qualitatively insensitive to the parameters of the proton-nucleus potential, i.e., changing the potential parameters over a fairly large range typically changes the decay width by no more than a factor of ∼3. Proton half-lives of observed heavy proton emitters are, in general, well reproduced by spherical calculations with the spectroscopic factors calculated in the independent quasiparticle approximation. The quantitative agreement with experimental data obtained in our study requires that the parameters of the proton-nucleus potential be chosen carefully. It also suggests that deformed proton emitters will provide invaluable spectroscopic information on the angular momentum decomposition of single-proton orbitals in deformed nuclei. copyright 1997 The American Physical Society
Experimental investigation of critical velocity in a parallel plate research reactor fuel assembly
Energy Technology Data Exchange (ETDEWEB)
Castro, Alfredo J.A.; Scuro, Nikolas L.; Andrade, Delvonei A., E-mail: ajcastro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNE-SP), Sao Paulo, SP (Brazil)
2017-07-01
The fuel elements of a MTR (Material Testing Reactor) type nuclear reactor are mostly composed of aluminum coated fuel plates containing the core of uranium silica (U{sub 3}Si{sub 2}) dispersed in an aluminum matrix. These plates have a thickness of the order of millimeters and are much longer in relation to their thickness. They are arranged in parallel in the assembly of the fuel element to form channels between them a few millimeters in thickness, through which there is a flow of the coolant. This configuration, combined with the need for a flow at high flow rates to ensure the cooling of the fuel element in operation, may create problems of mechanical failure of fuel plate due to the vibration induced by the flow in the channels. In the case of critical velocity excessive permanent deflections of the plates can cause blockage of the flow channel in the reactor core and lead to overheating in the plates. For this study an experimental bench capable of high volume flows and a test section that simulates a plate-like fuel element with three cooling channels were developed. The dimensions of the test section were based on the dimensions of the Fuel Element of the Brazilian Multipurpose Reactor (RMB), whose project is being coordinated by the National Commission of Nuclear Energy (CNEN). The experiments performed attained the objective of reaching Miller's critical velocity condition. The critical velocity was reached with 14.5 m/s leading to the consequent plastic deformation of the flow channel plates. (author)
International Nuclear Information System (INIS)
Horejs, C.
2011-01-01
Self-assembly of matter is one of nature's most sophisticated strategies to organize molecules on a large scale and to create order from disorder. Surface (S-)layer proteins self-assemble in a highly reproducible and robust fashion in order to form crystalline layers that completely cover and protect prokaryotic cells. Long conserved during evolution, S-layers constitute a unique model system to study the molecular mechanisms of functional self-assembly, while additionally, they provide a basic matrix for the specific construction of ordered nanostructures. Due to their intrinsic capabilities to self-assemble into two-dimensional crystals, the elucidation of the three-dimensional structure of single S-layer proteins demands an approach beyond conventional structure determination methods. In this work, computer simulations were combined with experimental techniques in order to study the structure and intra- and intermolecular potentials guiding the proteins to self-assemble into lattices with different symmetries. Molecular dynamics, Monte Carlo methods, small-angle X-ray scattering involving a new theoretical description, and AFM-based single-molecule force spectroscopy yield new insights into the three-dimensional structure of S-layer proteins, the location, type and distribution of amino acids in S-layer lattices, the molecular mechanisms behind the self-assembly process, the mechanical stability and adaptive structural conformations that S-layer proteins are able to establish. In silico studies - embedded in an adequate experimental and theoretical scaffold - offer the possibility to calculate structural and thermodynamic features of proteins, while this work demonstrates the growing impact of such theoretical techniques in the fascinating field of biophysics at the nano-scale. (author) [de
International Nuclear Information System (INIS)
LaFleur, A.; Menlove, H.; Park, S.-H.; Lee, S. K.; Oh, J.-M.; Kim, H.-D.
2015-01-01
The development of non-destructive assay (NDA) capabilities to improve partial defect verification of spent fuel assemblies is needed to improve the timely detection of the diversion of significant quantities of fissile material. This NDA capability is important to the implementation of integrated safeguards for spent fuel verification by the International Atomic Energy Agency (IAEA) and would improve deterrence of possible diversions by increasing the risk of early detection. A new NDA technique called Passive Neutron Multiplication Counter (PNMC) is currently being developed at Los Alamos National Laboratory (LANL) to improve safeguards measurements of LightWater Reactor (LWR) fuel assemblies. The PNMC uses the ratio of the fast-neutron emission rate to the thermalneutron emission rate to quantify the neutron multiplication of the item. The fast neutrons versus thermal neutrons are measured using fission chambers (FC) that have differential shielding to isolate fast and thermal energies. The fast-neutron emission rate is directly proportional to the neutron multiplication in the spent fuel assembly; whereas, the thermalneutron leakage is suppressed by the fissile material absorption in the assembly. These FCs are already implemented in the basic Self-Interrogation Neutron Resonance Densitometry (SINRD) detector package. Experimental measurements of fresh and spent PWR fuel assemblies were performed at LANL and the Korea Atomic Energy Research Institute (KAERI), respectively, using a hybrid PNMC and SINRD detector. The results from these measurements provides valuable experimental data that directly supports safeguards research and development (R&D) efforts on the viability of passive neutron NDA techniques and detector designs for partial defect verification of spent fuel assemblies. (author)
Arkhipkin, D. A.; Buttsev, V. S.; Chigrinov, S. E.; Kutuev, R. Kh.; Polanski, A.; Rakhno, I. L.; Sissakian, A.; Zulkarneev, R. Ya.; Zulkarneeva, Yu. R.
2003-07-01
The paper deals with theoretical and experimental investigation of transmutation rates for a number of long-lived fission products and minor actinides, as well as with neutron spectra formed in a subcritical assembly driven with the following monodirectional beams: 660-MeV protons and 14-MeV neutrons. In this work, the main objective is the comparison of neutron spectra in the MOX assembly for different external driving sources: a 660-MeV proton accelerator and a 14-MeV neutron generator. The SAD project (JINR, Russia) has being discussed. In the context of this project, a subcritical assembly consisting of a cylindrical lead target surrounded by a cylindrical MOX fuel layer will be constructed. Present conceptual design of the subcritical assembly is based on the core with a nominal unit capacity of 15 kW (thermal). This corresponds to a multiplication coefficient, keff= 0.945, and an accelerator beam power of 0.5 kW. The results of theoretical investigations on the possibility of incinerating long-lived fission products and minor actinides in fast neutron spectrum and formation of neutron spectra with different hardness in subcritical systems based on the MOX subcritical assembly are discussed. Calculated neutron spectra emitted from a lead target irradiated by a 660-MeV protons are also presented.
Energy Technology Data Exchange (ETDEWEB)
LaFleur, Adrienne M., E-mail: alafleur@lanl.gov; Menlove, Howard O., E-mail: hmenlove@lanl.gov
2015-05-01
Self-Interrogation Neutron Resonance Densitometry (SINRD) is a new NDA technique that was developed at Los Alamos National Laboratory (LANL) to improve existing nuclear safeguards measurements for LWR fuel assemblies. The SINRD detector consists of four fission chambers (FCs) wrapped with different absorber filters to isolate different parts of the neutron energy spectrum and one ion chamber (IC) to measure the gross gamma rate. As a result, two different techniques can be utilized using the same SINRD detector unit and hardware. These techniques are the Passive Neutron Multiplication Counter (PNMC) method and the SINRD method. The focus of the work described in this paper is the analysis of experimental measurements of fresh and spent PWR fuel assemblies that were performed at LANL and the Korea Atomic Energy Research Institute (KAERI), respectively, using the SINRD detector. The purpose of these experiments was to assess the following capabilities of the SINRD detector: 1) reproducibility of measurements to quantify systematic errors, 2) sensitivity to water gap between detector and fuel assembly, 3) sensitivity and penetrability to the removal of fuel rods from the assembly, and 4) use of PNMC/SINRD ratios to quantify neutron multiplication and/or fissile content. The results from these simulations and measurements provide valuable experimental data that directly supports safeguards research and development (R&D) efforts on the viability of passive neutron NDA techniques and detector designs for partial defect verification of spent fuel assemblies. - Highlights: • Experimental measurements of PWR fresh and spent FAs were performed with SINRD. • Good agreement of MCNPX and measured results confirmed accuracy of SINRD model. • For fresh fuel, SINRD and PNMC ratios were not sensitive to water gaps of ≤5-mm. • Practical use of SINRD would be in Fork detector to reduce systematic uncertainties.
Experimental study of hydrodynamically induced vibrational processes in VVER-440 fuel assemblies
International Nuclear Information System (INIS)
Solonin, V.I.; Perevezentsev, V.V.; Rekshnya, N.F.; Krapivtsev, V.G.
2000-01-01
Investigations are described of hydrodynamically induced vibrations in a single fuel assembly of a VVER-440 reactor, performed on a full-scale model installed in a closed loop filled with distilled water; the model fuel elements contained simulators of fuel pellets. Data on hydrodynamic loads were obtained by measuring pressure oscillations along the height of the fuel assembly case. Results of the measurements are presented in graphs and are discussed in some detail. (A.K.)
Directory of Open Access Journals (Sweden)
S. M. Dmitriev
2016-01-01
Full Text Available The results of experimental studies of local hydrodynamics and mass exchange of coolant flow behind spacer and mixing grids of different structural versions that were developed for fuel assemblies of domestic and foreign nuclear reactors are presented in the article. In order to carry out the study the models of the following fuel assemblies have been fabricated: FA for VVER and VBER, FA-KVADRAT for PWR-reactor and FA for KLT-40C reactor. All the models have been fabricated with a full geometrical similarity with full-scale fuel assemblies. The study was carried out by simulating the flow of coolant in a core by air on an aerodynamic test rig. In order to measure local hydrodynamic characteristics of coolant flow five-channel Pitot probes were used that enable to measure the velocity vector in a point by its three components. The tracerpropane method was used for studying mass transfer processes. Flow hydrodynamics was studied by measuring cross-section velocities of coolant flow and coolant rates according to the model cells. The investigation of mass exchange processes consisted of a study of concentration distribution for tracer in experimental model, in determination of attenuation lengths of mass transfer processes behind mixing grids, in calculating of inter-cellar mass exchange coefficient. The database on coolant flow in fuel assemblies for different types of reactors had been accumulated that formed the basis of the engineering substantiation of reactor cores designs. The recommendations on choice of optimal versions of mixing grids have been taken into consideration by implementers of the JSC “OKBM Afrikantov” when creating commissioned fuel assemblies. The results of the study are used for verification of CFD-codes and CFD programs of detailed cell-by-cell calculation of reactor cores in order to decrease conservatism for substantiation of thermal-mechanical reliability.
Wave propagation visualization in an experimental model for a control rod drive mechanism assembly
International Nuclear Information System (INIS)
Lee, Jung-Ryul; Jeong, Hyomi; Kong, Churl-Won
2011-01-01
Highlights: → We fabricate a full-scale mock-up of the control rod drive mechanism (CRDM) assembly in the upper reactor head of the nuclear power plant. → An ultrasonic propagation imaging method using a scanning laser ultrasonic generator is proposed to visualize and simulate ultrasonic wave propagation around the CRDM assembly. → The ultrasonic source location and frequency are simulated by changing the sensor location and the band pass-filtering zone. → The ultrasonic propagation patterns before and after cracks in the weld and nozzle of the CRDM assembly are analyzed. - Abstract: Nondestructive inspection techniques such as ultrasonic testing, eddy current testing, and visual testing are being developed to detect primary water stress corrosion cracks in control rod drive mechanism (CRDM) assemblies of nuclear power plants. A unit CRDM assembly consists of a reactor upper head including cladding, a penetration nozzle, and J-groove dissimilar metal welds with buttering. In this study, we fabricated a full-scale CRDM assembly mock-up. An ultrasonic propagation imaging (UPI) method using a scanning laser ultrasonic generator is proposed to visualize and simulate ultrasonic wave propagation around the thick and complex CRDM assembly. First, the proposed laser UPI system was validated for a simple aluminium plate by comparing the ultrasonic wave propagation movie (UWPM) obtained using the system with numerical simulation results reported in the literature. Lamb wave mode identification and damage detectability, depending on the ultrasonic frequency, were also included in the UWPM analysis. A CRDM assembly mock-up was fabricated in full-size and its vertical cross section was scanned using the laser UPI system to investigate the propagation characteristics of the longitudinal and Rayleigh waves in the complex structure. The ultrasonic source location and frequency were easily simulated by changing the sensor location and the band pass filtering zone
Assembly-history dynamics of a pitcher-plant protozoan community in experimental microcosms.
Directory of Open Access Journals (Sweden)
Kohmei Kadowaki
Full Text Available History drives community assembly through differences both in density (density effects and in the sequence in which species arrive (sequence effects. Density effects arise from predictable population dynamics, which are free of history, but sequence effects are due to a density-free mechanism, arising solely from the order and timing of immigration events. Few studies have determined how components of immigration history (timing, number of individuals, frequency alter local dynamics to determine community assembly, beyond addressing when immigration history produces historically contingent assembly.We varied density and sequence effects independently in a two-way factorial design to follow community assembly in a three-species aquatic protozoan community. A superior competitor, Colpoda steinii, mediated alternative community states; early arrival or high introduction density allowed this species to outcompete or suppress the other competitors (Poterioochromonas malhamensis and Eimeriidae gen. sp.. Multivariate analysis showed that density effects caused greater variation in community states, whereas sequence effects altered the mean community composition.A significant interaction between density and sequence effects suggests that we should refine our understanding of priority effects. These results highlight a practical need to understand not only the "ingredients" (species in ecological communities but their "recipes" as well.
Holographic Spherically Symmetric Metrics
Petri, Michael
The holographic principle (HP) conjectures, that the maximum number of degrees of freedom of any realistic physical system is proportional to the system's boundary area. The HP has its roots in the study of black holes. It has recently been applied to cosmological solutions. In this article we apply the HP to spherically symmetric static space-times. We find that any regular spherically symmetric object saturating the HP is subject to tight constraints on the (interior) metric, energy-density, temperature and entropy-density. Whenever gravity can be described by a metric theory, gravity is macroscopically scale invariant and the laws of thermodynamics hold locally and globally, the (interior) metric of a regular holographic object is uniquely determined up to a constant factor and the interior matter-state must follow well defined scaling relations. When the metric theory of gravity is general relativity, the interior matter has an overall string equation of state (EOS) and a unique total energy-density. Thus the holographic metric derived in this article can serve as simple interior 4D realization of Mathur's string fuzzball proposal. Some properties of the holographic metric and its possible experimental verification are discussed. The geodesics of the holographic metric describe an isotropically expanding (or contracting) universe with a nearly homogeneous matter-distribution within the local Hubble volume. Due to the overall string EOS the active gravitational mass-density is zero, resulting in a coasting expansion with Ht = 1, which is compatible with the recent GRB-data.
International Nuclear Information System (INIS)
Zuo Guomin; Li Xinxin
2011-01-01
This research is aimed at elucidating surface-energy (or interfacial energy) variation during the process of molecule-layer self-assembly on a solid surface. A quasi-quantitative plotting model is proposed and established to distinguish the surface-energy variation contributed by the three characteristic layers of a thiol-on-gold self-assembled monolayer (SAM), namely the assembly-medium correlative gold/head-group layer, the chain/chain interaction layer and the tail/medium layer, respectively. The data for building the model are experimentally extracted from a set of correlative thiol self-assemblies in different media. The variation in surface-energy during self-assembly is obtained by in situ recording of the self-assembly induced nanomechanical surface-stress using integrated micro-cantilever sensors. Based on the correlative self-assembly experiment, and by using the nanomechanically sensitive self-sensing cantilevers to monitor the self-assembly induced surface-stressin situ, the experimentally extracted separate contributions of the three layers to the overall surface-energy change aid a comprehensive understanding of the self-assembly mechanism. Moreover, the quasi-quantitative modeling method is helpful for optimal design, molecule synthesis and performance evaluation of molecule self-assembly for application-specific surface functionalization.
Progress in octahedral spherical hohlraum study
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Ke Lan
2016-01-01
Full Text Available In this paper, we give a review of our theoretical and experimental progress in octahedral spherical hohlraum study. From our theoretical study, the octahedral spherical hohlraums with 6 Laser Entrance Holes (LEHs of octahedral symmetry have robust high symmetry during the capsule implosion at hohlraum-to-capsule radius ratio larger than 3.7. In addition, the octahedral spherical hohlraums also have potential superiority on low backscattering without supplementary technology. We studied the laser arrangement and constraints of the octahedral spherical hohlraums, and gave a design on the laser arrangement for ignition octahedral hohlraums. As a result, the injection angle of laser beams of 50°–60° was proposed as the optimum candidate range for the octahedral spherical hohlraums. We proposed a novel octahedral spherical hohlraum with cylindrical LEHs and LEH shields, in order to increase the laser coupling efficiency and improve the capsule symmetry and to mitigate the influence of the wall blowoff on laser transport. We studied on the sensitivity of the octahedral spherical hohlraums to random errors and compared the sensitivity among the octahedral spherical hohlraums, the rugby hohlraums and the cylindrical hohlraums, and the results show that the octahedral spherical hohlraums are robust to these random errors while the cylindrical hohlraums are the most sensitive. Up till to now, we have carried out three experiments on the spherical hohlraum with 2 LEHs on Shenguang(SG laser facilities, including demonstration of improving laser transport by using the cylindrical LEHs in the spherical hohlraums, spherical hohlraum energetics on the SGIII prototype laser facility, and comparisons of laser plasma instabilities between the spherical hohlraums and the cylindrical hohlraums on the SGIII laser facility.
Energy Technology Data Exchange (ETDEWEB)
Raisic, N M; Popovic, D D; Takac, S M; Djordjevic, M M [Boris Kidric Institute of Nuclear Sciences, Vinca, Beograd (Yugoslavia)
1960-03-15
The buckling in the bare heavy water natural uranium critical assembly was determined by measuring the thermal neutron flux distribution. The obtained value for the critical buckling at the temperature of 20 deg C is: B{sup 2} = (8.516 {+-} 0.02) m{sup -2}. The above error is a statistical one, obtained from several series of measurements. The possible systematic error was estimated as 0.1 m{sup -2}. (author)
International Nuclear Information System (INIS)
Raisic, N.M.; Popovic, D.D.; Takac, S.M.; Djordjevic, M.M.
1960-01-01
The buckling in the bare heavy water natural uranium critical assembly was determined by measuring the thermal neutron flux distribution. The obtained value for the critical buckling at the temperature of 20 deg C is: B 2 = (8.516 ± 0.02) m -2 . The above error is a statistical one, obtained from several series of measurements. The possible systematic error was estimated as 0.1 m -2 . (author)
Energy Technology Data Exchange (ETDEWEB)
Gordel, M., E-mail: marta.gordel@pwr.edu.pl [Wrocław University of Technology, Advanced Materials Engineering and Modelling Group, Faculty of Chemistry (Poland); Piela, K., E-mail: katarzyna.piela@pwr.edu.pl [Wrocław University of Technology, Department of Physical and Quantum Chemistry (Poland); Kołkowski, R. [Wrocław University of Technology, Advanced Materials Engineering and Modelling Group, Faculty of Chemistry (Poland); Koźlecki, T. [Wrocław University of Technology, Department of Chemical Engineering, Faculty of Chemistry (Poland); Buckle, M. [CNRS, École Normale Supérieure de Cachan, Laboratoire de Biologie et Pharmacologie Appliquée (France); Samoć, M. [Wrocław University of Technology, Advanced Materials Engineering and Modelling Group, Faculty of Chemistry (Poland)
2015-12-15
We describe here a modification of properties of colloidal gold nanorods (NRs) resulting from the chemical treatment used to carry out their transfer into isopropanol (IPA) solution. The NRs acquire a tendency to attach one to another by their ends (end-to-end assembly). We focus on the investigation of the change in position and shape of the longitudinal surface plasmon (l-SPR) band after self-assembly. The experimental results are supported by a theoretical calculation, which rationalizes the dramatic change in optical properties when the NRs are positioned end-to-end at short distances. The detailed spectroscopic characterization performed at the consecutive stages of transfer of the NRs from water into IPA solution revealed the features of the interaction between the polymers used as ligands and their contribution to the final stage, when the NRs were dispersed in IPA solution. The efficient method of aligning the NRs detailed here may facilitate applications of the self-assembled NRs as building blocks for optical materials and biological sensing.Graphical Abstract.
Comparison of calculated and experimental results of fuel bunching in VERA assemblies 1B, 3A and 5A
International Nuclear Information System (INIS)
Matthews, J.D.
1964-12-01
Comparison is made of experimental and calculated reactivity changes when the fuel plates of the VERA assemblies are bunched from 1/8 in. thickness to 1/2 in. In addition, U238 fine structure reaction rates are studied. The method used is that investigated in detail by James and Matthews ('A Perturbation Method for Multigroup Neutron Transport Calculations in Plane Lattices', AEEW - R 219), while the multigroup data sets used are both those of Yiftah, Okrent and Moldauer, and Roach. The method and data give only rough agreement with experimental reactivity changes, with a tendency to over-predict the results. U238 fission rates are in better agreement, though the method predicts too small a variation for the U238 capture rate across a cell. (author)
Oh, Hyun-Ung; Lee, Min-Kyu; Shin, Somin; Hong, Joo-Sung
2011-09-01
Spaceborne pulse tube type cryocoolers are widely used for providing cryogenic temperatures for sensitive infrared, gamma-ray and X-ray detectors. Thermal control for the compressor of the cryocooler is one of the important technologies for the cooling performance, mission life time, and jitter stability of the cooler. The thermal design of the compressor assembly proposed in this study is basically composed of a heat pipe, a radiator, and a heater. In the present work, a method for heat pipe implementation is proposed and investigated to ensure the jitter stability of the compressor under the condition that one heat pipe is not working. An optimal design of the radiator that uses ribs for effective use by minimizing the temperature gradient on the radiator and reducing its weight is introduced. The effectiveness of the thermal design of the compressor assembly is demonstrated by on-orbit thermal analysis using the correlated thermal model obtained from the thermal balance test that is performed under a space simulating environment.
International Nuclear Information System (INIS)
Lelong, Franck
2010-01-01
In a pressurized water reactor (PWR), during a Loss Of Coolant Accident (LOCA), liquid water evaporates and the fuel assemblies are not cooled anymore; as a consequence, the temperature rises to such an extent that some parts of the fuel assemblies can be deformed resulting in 'ballooned regions'. When reflooding occurs, the cooling of these partially blocked parts of the fuel assemblies will depend on the coolant flow that is a mixture of overheated vapour and under-saturated droplets. The aim of this thesis is to study the heat transfer between droplets and hot walls of the fuel rods. In this purpose, an experimental device has been designed in accordance with droplets and wall features (droplet velocity and diameter, wall temperature) representative of LOCA conditions. The cooling of a hot Nickel disk, previously heated by induction, is cooled down by a stream of monodispersed droplet. The rear face temperature profiles are measured by infrared thermography. Then, the estimation of wall heat flux is performed by an inverse conduction technique from these infrared images. The effect of droplet dynamical properties (diameter, velocity) on the heat flux is studied. These experimental data allow us to validate an analytical model of heat exchange between droplet and hot slab. This model is based on combined dynamical and thermal considerations. On the one hand, the droplet dynamics is considered through a spring analogy in order to evaluate the evolution of droplet features such as the spreading diameter when the droplet is squeezed over the hot surface. On the other hand, thermal parameters, such as the thickness of the vapour cushion beneath the droplet, are determined from an energy balance. In the short term, this model will be integrated in a CFD code (named NEPTUNE-CFD) to simulate the cooling of a reactor core during a LOCA, taking into account the droplet/wall heat exchange. (author)
Barnard, Anna; Posocco, Paola; Pricl, Sabrina; Calderon, Marcelo; Haag, Rainer; Hwang, Mark E; Shum, Victor W T; Pack, Daniel W; Smith, David K
2011-12-21
This paper uses a combined experimental and theoretical approach to gain unique insight into gene delivery. We report the synthesis and investigation of a new family of second-generation dendrons with four triamine surface ligands capable of binding to DNA, degradable aliphatic-ester dendritic scaffolds, and hydrophobic units at their focal points. Dendron self-assembly significantly enhances DNA binding as monitored by a range of experimental methods and confirmed by multiscale modeling. Cellular uptake studies indicate that some of these dendrons are highly effective at transporting DNA into cells (ca. 10 times better than poly(ethyleneimine), PEI). However, levels of transgene expression are relatively low (ca. 10% of PEI). This indicates that these dendrons cannot navigate all of the intracellular barriers to gene delivery. The addition of chloroquine indicates that endosomal escape is not the limiting factor in this case, and it is shown, both experimentally and theoretically, that gene delivery can be correlated with the ability of the dendron assemblies to release DNA. Mass spectrometric assays demonstrate that the dendrons, as intended, do degrade under biologically relevant conditions over a period of hours. Multiscale modeling of degraded dendron structures suggests that complete dendron degradation would be required for DNA release. Importantly, in the presence of the lower pH associated with endosomes, or when bound to DNA, complete degradation of these dendrons becomes ineffective on the transfection time scale-we propose this explains the poor transfection performance of these dendrons. As such, this paper demonstrates that taking this kind of multidisciplinary approach can yield a fundamental insight into the way in which dendrons can navigate barriers to cellular uptake. Lessons learned from this work will inform future dendron design for enhanced gene delivery. © 2011 American Chemical Society
Some manufacture and installation problems in experimental assemblies for fusion research
International Nuclear Information System (INIS)
Partridge, J.E.; Rappe, G.; Hoare, F.; McDonald, J.
1976-01-01
Many of the manufacturing problems encountered when developing specialised items of fusion apparatus are only solved after much experimentation and a good deal of trial and error. After the experiment is built such problems may be forgotten and are often not recorded so that subsequent workers in the same field may start with no past experience on which to build. The paper therefore highlights some of the manufacturing problems which have been solved during the construction of some of the experimental apparatus at Culham
Directory of Open Access Journals (Sweden)
CHEOL HO PYEON
2013-02-01
Full Text Available Neutron spectrum analyses of spallation neutrons are conducted in the accelerator-driven system (ADS facility at the Kyoto University Critical Assembly (KUCA. High-energy protons (100 MeV obtained from the fixed field alternating gradient accelerator are injected onto a tungsten target, whereby the spallation neutrons are generated. For neutronic characteristics of spallation neutrons, the reaction rates and the continuous energy distribution of spallation neutrons are measured by the foil activation method and by an organic liquid scintillator, respectively. Numerical calculations are executed by MCNPX with JENDL/HE-2007 and ENDF/B-VI libraries to evaluate the reaction rates of activation foils (bismuth and indium set at the target and the continuous energy distribution of spallation neutrons set in front of the target. For the reaction rates by the foil activation method, the C/E values between the experiments and the calculations are found around a relative difference of 10%, except for some reactions. For continuous energy distribution by the organic liquid scintillator, the spallation neutrons are observed up to 45 MeV. From these results, the neutron spectrum information on the spallation neutrons generated at the target are attained successfully in injecting 100 MeV protons onto the tungsten target.
Experimental Studies on Assemblies 1 and 2 of the Fast Reactor FR-0. Part 2
Energy Technology Data Exchange (ETDEWEB)
Hellstrand, E; Andersson, T L; Brunfelter, B; Kockum, J; Londen, S O; Tiren, L I
1965-12-15
In a first part of this report, published as AE-195, an account was given of critical mass determinations and measurements of flux distribution and reaction ratios in the first assemblies of the fast zero power reactor FR0. This second part of the report deals with various investigations involving the measurement of reactivity. Control rod calibrations have been made using the positive period, the inverse multiplication, the rod drop and the pulsed source techniques, and show satisfactory agreement between the various methods. The reactivity worths of samples of different materials and different sizes have been measured at the core centre. Comparisons with perturbation calculations show that the regular and adjoint fluxes are well predicted in the central region of the core. The variation in the prompt neutron life-time with reactivity has been studied by means of the pulsed source and the Rossi-{alpha} techniques. Comparison with one region calculations reveals large discrepancies, indicating that this simple model is inadequate. Some investigations of streaming effects in an empty channel in the reactor and of interaction effects between channels have been made and are compared with theoretical estimates. Measurements of the reactivity worth of an air gap between the reactor halves and of the temperature coefficient are also described in the report. The work has been performed as a joint effort by AB Atomenergi and the Research Institute of National Defence.
Große Perdekamp, Markus; Braunwarth, Roland; Kromeier, Jan; Nadjem, Hadi; Pollak, Stefan; Thierauf, Annette
2013-07-01
In current forensic practice, fatal injuries from black powder guns are rare events. In contact and close-range shots, the intensity of GSR deposition (soot, powder particles) is much greater than that in shots with smokeless powder ammunition. The same applies to any burning effects from the combustion gases. Besides, a wad of felt interposed between the propellant and the lead bullet may enter the wound channel. Apart from these findings seen in close-range shots, another characteristic feature results from the mostly spherical shape of the missiles causing maximum tissue damage at the entrance site. Two fatal injuries inflicted with muzzle-loading weapons are reported. In the first case, suicide was committed with a cal. 11.6 mm miniature cannon by firing a contact shot to the back of the neck. In test shots using black powder (1 and 2 g) as propellant, the mean bullet velocity measured 1 m away from the weapon was 87.11 and 146.85 m/s, respectively, corresponding to a kinetic energy of 32.49 and 92.95 J, respectively. Contact test shots to composite models consisting of ballistic soap covered by pig skin at the entrance site were evaluated by CT and revealed cone-like cavitations along the bullet path as known from spherical missiles and penetration depths up to 25 cm. The second case presented deals with a homicidal close-range shot discharged from a muzzle-loading percussion pistol cal. .44. The skin around the entrance site (root of the nose) was densely covered with blackish soot and powder particles, whereas the eyebrows and eyelashes showed singeing of the hairs. The flattened bullet and the wad had got stuck under the scalp of the occipital region. In both cases, there was a disproportionally large zone of tissue destruction in the initial parts of the wound tracks.
Are Nanoparticles Spherical or Quasi-Spherical?
Sokolov, Stanislav V; Batchelor-McAuley, Christopher; Tschulik, Kristina; Fletcher, Stephen; Compton, Richard G
2015-07-20
The geometry of quasi-spherical nanoparticles is investigated. The combination of SEM imaging and electrochemical nano-impact experiments is demonstrated to allow sizing and characterization of the geometry of single silver nanoparticles. © 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.
International Nuclear Information System (INIS)
Semmler, R.
1993-01-01
A new experimental apparatus has been mounted at the tangential beam tube B H 4/12 of the IPEN IEA-R1 (2 MW) reactor, for production and utilization of capture gamma rays. In this type of experiment, monochromatic gamma radiation, with energy resolution of about 10 eV, is produced by thermal neutron capture in several materials placed near the reactor core. By changing the target material it was possible to obtain up to 30 gamma lines in the 5 to 11 MeV energy range and so, the present experimental arrangement may be considered as an excellent gamma ray source for photonuclear reactions studies in low excitation energies. (author)
Leung, Ka-Ngo
2006-11-21
A spherical neutron generator is formed with a small spherical target and a spherical shell RF-driven plasma ion source surrounding the target. A deuterium (or deuterium and tritium) ion plasma is produced by RF excitation in the plasma ion source using an RF antenna. The plasma generation region is a spherical shell between an outer chamber and an inner extraction electrode. A spherical neutron generating target is at the center of the chamber and is biased negatively with respect to the extraction electrode which contains many holes. Ions passing through the holes in the extraction electrode are focused onto the target which produces neutrons by D-D or D-T reactions.
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Domenico Gentile
2018-01-01
Full Text Available In the present work, the fracture resistance of a carbon fiber composite under mode I and mode II loading have been experimentally determined. For the mode I and II, the energy release rate G has been determinate for each material. In some cases, only a single estimation of G was possible due to problems in the propagation such as extensive fiber bridging and loss of planarity of the running crack. The experimental results relative to DCB tests have been analyzed in order to derive statistical trends. Only the samples for which more than three crack advance data points have been collected are considered in the analysis. The G values are those obtained with the compliance calibration method (CC. For ENF test, determination of critical GII, in addition to the value calculated with the relationship given in the prescription EN6034, other two values, the non linear and visual non linear, are also given. The crack propagation resulted to be unstable for all specimens tested and only a single value of GII could be determined
START: the creation of a spherical tokamak
International Nuclear Information System (INIS)
Sykes, Alan
1992-01-01
The START (Small Tight Aspect Ratio Tokamak) plasma fusion experiment is now operational at AEA Fusion's Culham Laboratory. It is the world's first experiment to explore an extreme limit of the tokamak - the Spherical Tokamak - which theoretical studies predict may have substantial advantages in the search for economic fusion power. The Head of the START project, describes the concept, some of the initial experimental results and the possibility of developing a spherical tokamak power reactor. (author)
The prediction of spherical aberration with schematic eyes.
Liou, H L; Brennan, N A
1996-07-01
Many model eyes have been proposed; they differ in optical characteristics and therefore have different aberrations and image quality. In predicting the visual performance of the eye, we are most concerned with the central foveal vision. Spherical aberration is the only on-axis monochromatic aberration and can be used as a criterion to assess the degree of resemblance of eye models to the human eye. We reviewed and compiled experimental values of the spherical aberration of the eye, calculated the spherical aberration of several different categories of model eyes and compared the calculated results to the experimental data. Results show an over-estimation of spherical aberration by all models, the finite schematic eyes predicting values of spherical aberration closest to the experimental data. Current model eyes do not predict the average experimental values of the spherical aberration of the eye. A new model eye satisfying this assessment criterion is required for investigations of the visual performance of the eye.
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Ivan Fernandez-Bueno
2015-01-01
Full Text Available Purpose. To evaluate clinically and histologically the safety and biocompatibility of a new HDPE-based spherical porous orbital implants in rabbits. Methods. MEDPOR (Porex Surgical, Inc., Fairburn, GA, USA, OCULFIT I, and OCULFIT II (AJL Ophthalmic S.A., Vitoria, Spain implants were implanted in eviscerated rabbis. Animals were randomly divided into 6 groups (n=4 each according to the 3 implant materials tested and 2 follow-up times of 90 or 180 days. Signs of regional pain and presence of eyelid swelling, conjunctival hyperemia, and amount of exudate were semiquantitatively evaluated. After animals sacrifice, the implants and surrounding ocular tissues were processed for histological staining and polarized light evaluation. Statistical study was performed by ANOVA and Kaplan-Meier analysis. Results. No statistically significant differences in regional pain, eyelid swelling, or conjunctival hyperemia were shown between implants and/or time points evaluated. However, amount of exudate differed, with OCULFIT I causing the smallest amount. No remarkable clinical complications were observed. Histological findings were similar in all three types of implants and agree with minor inflammatory response. Conclusions. OCULFIT ophthalmic tolerance and biocompatibility in rabbits were comparable to the clinically used MEDPOR. Clinical studies are needed to determine if OCULFIT is superior to the orbital implants commercially available.
Fernandez-Bueno, Ivan; Di Lauro, Salvatore; Alvarez, Ivan; Lopez, Jose Carlos; Garcia-Gutierrez, Maria Teresa; Fernandez, Itziar; Larra, Eva; Pastor, Jose Carlos
2015-01-01
Purpose. To evaluate clinically and histologically the safety and biocompatibility of a new HDPE-based spherical porous orbital implants in rabbits. Methods. MEDPOR (Porex Surgical, Inc., Fairburn, GA, USA), OCULFIT I, and OCULFIT II (AJL Ophthalmic S.A., Vitoria, Spain) implants were implanted in eviscerated rabbis. Animals were randomly divided into 6 groups (n = 4 each) according to the 3 implant materials tested and 2 follow-up times of 90 or 180 days. Signs of regional pain and presence of eyelid swelling, conjunctival hyperemia, and amount of exudate were semiquantitatively evaluated. After animals sacrifice, the implants and surrounding ocular tissues were processed for histological staining and polarized light evaluation. Statistical study was performed by ANOVA and Kaplan-Meier analysis. Results. No statistically significant differences in regional pain, eyelid swelling, or conjunctival hyperemia were shown between implants and/or time points evaluated. However, amount of exudate differed, with OCULFIT I causing the smallest amount. No remarkable clinical complications were observed. Histological findings were similar in all three types of implants and agree with minor inflammatory response. Conclusions. OCULFIT ophthalmic tolerance and biocompatibility in rabbits were comparable to the clinically used MEDPOR. Clinical studies are needed to determine if OCULFIT is superior to the orbital implants commercially available. PMID:26689343
Friction factor for water flow through packed beds of spherical and non-spherical particles
Directory of Open Access Journals (Sweden)
Kaluđerović-Radoičić Tatjana
2017-01-01
Full Text Available The aim of this work was the experimental evaluation of different friction factor correlations for water flow through packed beds of spherical and non-spherical particles at ambient temperature. The experiments were performed by measuring the pressure drop across the bed. Packed beds made of monosized glass spherical particles of seven different diameters were used, as well as beds made of 16 fractions of quartz filtration sand obtained by sieving (polydisperse non-spherical particles. The range of bed voidages was 0.359–0.486, while the range of bed particle Reynolds numbers was from 0.3 to 286 for spherical particles and from 0.1 to 50 for non-spherical particles. The obtained results were compared using a number of available literature correlations. In order to improve the correlation results for spherical particles, a new simple equation was proposed in the form of Ergun’s equation, with modified coefficients. The new correlation had a mean absolute deviation between experimental and calculated values of pressure drop of 9.04%. For non-spherical quartz filtration sand particles the best fit was obtained using Ergun’s equation, with a mean absolute deviation of 10.36%. Surface-volume diameter (dSV necessary for correlating the data for filtration sand particles was calculated based on correlations for dV = f(dm and Ψ = f(dm. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. ON172022
Electrostatic axisymmetric mirror with removable spherical aberration
International Nuclear Information System (INIS)
Birmuzaev, S.B.; Serikbaeva, G.S.; Hizirova, M.A.
1999-01-01
The electrostatic axisymmetric mirror, assembled from three coaxial cylinders with an equal diameter d and under the potential v1, v2 and v3, was computed. The proportions of geometrical and electric parameters of the mirror, with which the spherical 3-order aberration may be eliminated, were determined. The computation outcomes of the case, when the focal power of the mirror is enough large and the object plane in the focus is out of its field, are presented (Fig. 1 - potentials proportion that makes elimination of the spherical aberration possible; Fig. 2 - the focus coordinates when the spherical aberration is eliminated). The geometrical values are presented by d, and the electric ones are presented by v1. The figures on the curves present a length of the second (middle) electrode. The zero point is located in the middle of the gap between the first and second electrodes The investigated mirror may be used as a lens for the transmission electron microscope
International Nuclear Information System (INIS)
Ricciardi, G.
2008-10-01
The designing of a pressurized water reactor core subjected to seismic loading, is a major concern of the nuclear industry. We propose, in this PhD report, to establish the global behaviour equations of the core, in term of a porous medium. Local equations of fluid and structure are space averaged on a control volume, thus we define an equivalent fluid and an equivalent structure, of which unknowns are defined on the whole space. The non-linear fuel assemblies behaviour is modelled by a visco-elastic constitutive law. The fluid-structure coupling is accounted for by a body force, the expression of that force is based on empirical formula of fluid forces acting on a tube subject to an axial flow. The resulting equations are solved using a finite element method. A validation of the model, on three experimental device, is proposed. The first one presents two fuel assemblies subjected to axial flow. One of the two fuel assemblies is deviated from its position of equilibrium and released, while the other is at rest. The second one presents a six assemblies row, immersed in water, placed on a shaking table that can simulate seismic loading. Finally, the last one presents nine fuel assemblies network, arranged in a three by three, subject to an axial flow. The displacement of the central fuel assembly is imposed. The simulations are in agreement with the experiments, the model reproduces the influence of the flow of fluid on the dynamics and coupling of the fuel assemblies. (author)
International Nuclear Information System (INIS)
Bierman, S.R.
1989-10-01
A research program was initiated for the US Department of Energy (DOE) Sandia National Laboratory Transportation Systems Development Department in 1982 to provide benchmark type experimental criticality data in support of the design and safe operations of nuclear fuel transportation systems. The overall objective of the program is to identify and provide the experimental data needed to form a consistent, firm, and complete data base for verifying calculational models used in the criticality analyses of nuclear transport and related systems. A report, PNL-6205, issued in June 1988 (Bierman 1988) covered measurement results obtained from a series of experimental assemblies (TIC-1, 2, 3 and 4) involving neutron flux traps. The results obtained on a fifth experimental assembly (TIC-5), modeled after a calculational problem of the Organization for Economic Cooperation and Development (OECD) Nuclear Energy Agency (NEA) Committee on the Safety of Nuclear Installations (CSNI) Working Group, are covered in this report. 10 refs., 10 figs., 7 tabs
A Spherical Aerial Terrestrial Robot
Dudley, Christopher J.
This thesis focuses on the design of a novel, ultra-lightweight spherical aerial terrestrial robot (ATR). The ATR has the ability to fly through the air or roll on the ground, for applications that include search and rescue, mapping, surveillance, environmental sensing, and entertainment. The design centers around a micro-quadcopter encased in a lightweight spherical exoskeleton that can rotate about the quadcopter. The spherical exoskeleton offers agile ground locomotion while maintaining characteristics of a basic aerial robot in flying mode. A model of the system dynamics for both modes of locomotion is presented and utilized in simulations to generate potential trajectories for aerial and terrestrial locomotion. Details of the quadcopter and exoskeleton design and fabrication are discussed, including the robot's turning characteristic over ground and the spring-steel exoskeleton with carbon fiber axle. The capabilities of the ATR are experimentally tested and are in good agreement with model-simulated performance. An energy analysis is presented to validate the overall efficiency of the robot in both modes of locomotion. Experimentally-supported estimates show that the ATR can roll along the ground for over 12 minutes and cover the distance of 1.7 km, or it can fly for 4.82 minutes and travel 469 m, on a single 350 mAh battery. Compared to a traditional flying-only robot, the ATR traveling over the same distance in rolling mode is 2.63-times more efficient, and in flying mode the system is only 39 percent less efficient. Experimental results also demonstrate the ATR's transition from rolling to flying mode.
Directory of Open Access Journals (Sweden)
Pham Thu Nga
2017-11-01
Full Text Available In this contribution we present an experimental study of 3D opal photonic crystals. The samples are opals constituted by colloidal silica spheres, realized with self-assembly technique. The sphere diameter is selected in order to obtain coupling of the photonic band gap with the emission from CdSe/ZnS colloidal quantum dots. The quantum dots infiltrated in the opals is expected to be enhanced or suppressed depending on the detection angle from the photonic crystal. The structural and optical characterization of the SiO2 opal photonic crystals are performed by field-emission scanning electron microscopy and reflectivity spectroscopy. Measurements performed on samples permits to put into evidence the influence of the different preparation methods on the optical properties. Study of self-activated luminescence of the pure opals is also presented. It is shown that the luminescence of the sample with QDs have original QD emission and not due to the photonic crystal structure. The optical properties of colloidal core-shell semiconductor quantum dots of CdSe/ZnS which are prepared in our lab will be mention.
Flow and scour around spherical bodies
DEFF Research Database (Denmark)
Truelsen, Christoffer
2003-01-01
Spherical bodies placed in the marine environment may bury themselves due to the action of the waves and the current on the sediment in their immediate neighborhood. The present study addresses this topic by a numerical and an experimental investigation of the flow and scour around a spherical body...... results except in the critical flow regime. For flow around a near-wall sphere, a weak horseshoe vortex emerges as the gap ratio becomes less than or equal to 0.3. In Chapter 3, a RANS flow solver has been used to compute the bed shear stress for a near-wall sphere. The model results compare well...... 4, an experimental study on the scour around spherical bodies and self-burial in sand for steady current and waves has been carried out. The effect of the contraction of streamlines is found to be the key element in the scour process both for steady current and waves. Furthermore, it is demonstrated...
Effect of Rolling Resistance in Dem Models With Spherical Bodies
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Dubina Radek
2016-12-01
Full Text Available The rolling resistance is an artificial moment arising on the contact of two discrete elements which mimics resistance of two grains of complex shape in contact rolling relatively to each other. The paper investigates the influence of rolling resistance on behaviour of an assembly of spherical discrete elements. Besides the resistance to rolling, the contacts between spherical particles obey the Hertzian law in normal straining and Coulomb model of friction in shear.
Energy Technology Data Exchange (ETDEWEB)
Grimm, P.; Perret, G. [Paul Scherrer Inst., CH-5232 Villigen PSI (Switzerland)
2012-07-01
Measured and calculated radial total fission rate distributions are compared for the three axial sections of a Westinghouse SVEA-96 Optima2 BWR fuel assembly, comprising 96, 92 and 84 fuel rods, respectively. The measurements were performed on a full-size fuel assembly in the PROTEUS zero-power experimental facility. The measured fission rates are compared to the results of the CASMO-4E and CASMO-5M fuel assembly codes. Detailed measured geometrical data were used in the models, and effects of the surrounding zones of the reactor were taken into account by correction factors derived from MCNPX calculations. The results of the calculations agree well with those of the experiments, with root-mean-square deviations between 1.2% and 1.5% and maximum deviations of 3-4%. The quality of the predictions by CASMO-4E and CASMO-5M is comparable. (authors)
The Spherical Deformation Model
DEFF Research Database (Denmark)
Hobolth, Asgar
2003-01-01
Miller et al. (1994) describe a model for representing spatial objects with no obvious landmarks. Each object is represented by a global translation and a normal deformation of a sphere. The normal deformation is defined via the orthonormal spherical-harmonic basis. In this paper we analyse the s...
International Nuclear Information System (INIS)
Hejna, J.; Vosahlo, L.; Cervenka, J.; Smid, J.
Aerodynamic model HEM-2 was used for the first stage of experiments aimed at obtaining data allowing to determine the effect of assembly configuration changes on hydrodynamic conditions. The results are given of measuring tangential stresses and velocity fields. (Ha)
International Nuclear Information System (INIS)
Jesus Barbosa, S. de.
1987-01-01
The effective multiplication factor and the nuclear parameters associated with the variation of (RESUCO- Subcritical Experimental Reactor of Uranium with Oxygen) Subcritical Assembly Configuration, using pulsed neutron technique are analysed. BF3 detectors were used to detect the variation of thermal neutrons in the system, positioned parallelly to fuel elements, and a proton recoil detector was used for monitoring the neutron generation. (M.C.K.) [pt
Spherical rhenium metal powder
International Nuclear Information System (INIS)
Leonhardt, T.; Moore, N.; Hamister, M.
2001-01-01
The development of a high-density, spherical rhenium powder (SReP) possessing excellent flow characteristics has enabled the use of advanced processing techniques for the manufacture of rhenium components. The techniques that were investigated were vacuum plasma spraying (VPS), direct-hot isostatic pressing (D-HIP), and various other traditional powder metallurgy processing methods of forming rhenium powder into near-net shaped components. The principal disadvantages of standard rhenium metal powder (RMP) for advanced consolidation applications include: poor flow characteristics; high oxygen content; and low and varying packing densities. SReP will lower costs, reduce processing times, and improve yields when manufacturing powder metallurgy rhenium components. The results of the powder characterization of spherical rhenium powder and the consolidation of the SReP are further discussed. (author)
The Spherical Deformation Model
DEFF Research Database (Denmark)
Hobolth, Asgar
2003-01-01
Miller et al. (1994) describe a model for representing spatial objects with no obvious landmarks. Each object is represented by a global translation and a normal deformation of a sphere. The normal deformation is defined via the orthonormal spherical-harmonic basis. In this paper we analyse the s...... a single central section of the object. We use maximum-likelihood-based inference for this purpose and demonstrate the suggested methods on real data....
Mechanics of a crushable pebble assembly using discrete element method
International Nuclear Information System (INIS)
Annabattula, R.K.; Gan, Y.; Zhao, S.; Kamlah, M.
2012-01-01
The influence of crushing of individual pebbles on the overall strength of a pebble assembly is investigated using discrete element method. An assembly comprising of 5000 spherical pebbles is assigned with random critical failure energies with a Weibull distribution in accordance with the experimental observation. Then, the pebble assembly is subjected to uni-axial compression (ε 33 =1.5%) with periodic boundary conditions. The crushable pebble assembly shows a significant difference in stress–strain response in comparison to a non-crushable pebble assembly. The analysis shows that a ideal plasticity like behaviour (constant stress with increase in strain) is the characteristic of a crushable pebble assembly with sudden damage. The damage accumulation law plays a critical role in determining the critical stress while the critical number of completely failed pebbles at the onset of critical stress is independent of such a damage law. Furthermore, a loosely packed pebble assembly shows a higher crush resistance while the critical stress is insensitive to the packing factor (η) of the assembly.
International Nuclear Information System (INIS)
Makarov, V.; Afanasiev, A.; Egorov, Yu.; Matvienko, I.
2015-01-01
The paper covers the results of the studies performed to justify the wear resistance of fuel rods in contact with the spacer grids of TVS VVER-1000 fuel assembly and TVS-KVADRAT square fuel assembly of Russian design for PWR-900 reactor. The presented results of three testing stages comprise: Testing of mockup fuel rods of VVER TVS fuel assembly for fretting wear under the conditions of the water chemistry of VVER reactor; Testing models of different design embodiments of the fuel rods for VVER TVS fuel assembly for fretting wear in still cold water; Testing mockup fuel rods of TVS-KVADRAT square fuel assembly for PWR reactor for frettingwear under the conditions of PWR water chemistry. The effect of structural and operational factors was determined (amplitudes, fuel rod vibration frequencies, values of cladding-to-spacer grid cell gap for the depth of fuel rod cladding wear etc.), an assessment was made of the threshold values of fuel rod vibration parameters, which, if not exceeded, provide the absence of the fuel rod cladding fretting wear in the fuel rod-to spacer grid contact area. Key words: fretting wear, fuel rod, spacer grid, VVER, PWR (author)
Scaling of a fast spherical discharge
Energy Technology Data Exchange (ETDEWEB)
Antsiferov, P. S., E-mail: Ants@isan.troitsk.ru; Dorokhin, L. A. [Russian Academy of Sciences, Institute of Spectroscopy (Russian Federation)
2017-02-15
The influence of the discharge cavity dimensions on the properties of the spherical plasma formed in a fast discharge was studied experimentally. The passage of a current pulse with an amplitude of 30–40 kA and a rise rate of ~10{sup 12} A/s (a fast discharge) through a spherical ceramic (Al{sub 2}O{sub 3}) cavity with an inner diameter of 11 mm filled with argon at a pressure of 80 Pa results in the formation of a 1- to 2-mm-diameter spherical plasma with an electron temperature of several tens of electronvolts and a density of 10{sup 18}–10{sup 19} cm{sup –3}. It is shown that an increase in the inner diameter of the discharge cavity from 11 to 21 mm leads to the fourfold increase in the formation time of the spherical plasma and a decrease in the average ion charge. A decrease in the cavity diameter to 7 mm makes the spherical plasma unstable.
Studies of spherical inertial-electrostatic confinement
International Nuclear Information System (INIS)
Miley, G.H.
1992-01-01
Theoretical and experimental results from studies of Spherical Inertial-Electrostatic Confinement (SIEC) are presented. This principle of IEC involves the confinement by multiple potential wells created by ion injection into a spherical device containing biased grids. A semitransparent cathode accelerates ions, generating a spherical ion-beam flow which converges at the center of the spherical volume, creating a space charge (potential well) region. An electron flow is created by the core (virtual anode) region, forming in turn a virtual cathode. Ions trapped inside this well oscillate back and forth until they fuse or degrade in energy. Such multiple wells with virtual anodes and cathodes, have been called ''Poissors'' following the original work by Farnsworth and by Hirsch. Fusion within the core occurs by reactions between non-Maxwellian beam-beam type ions. This has the potential for achieving a high power density and also for burning both D-T and advanced fuels. If successful, such a device would be attractive for a variety of high power density applications, e.g., space power or as a neutron source based on D-D or D-T operation. Simulations of recent SIEC experiments have been carried out using the XL-code, to solve Poisson's equation, self-consistently with the collisionless Vlasov equation in spherical geometry for several current species and grid parameters. The potential profile predictions are reasonably consistent with experimental results. Potential well measurements used a collimated proton detector. Results indicate that an ∼ 15-kV virtual anode, at least one centimeter in radius, was formed in a spherical device with a cathode potential of 30 kV using an ion current of ∼ 30 mA. Analysis indicates D + densities on the order of 10 9 cm -3 , and D 2 + densities on the order of 10 10 cm -3 . Steady-state D-D neutron emission of about 10 6 n/sec is observed
Fundamentals of spherical array processing
Rafaely, Boaz
2015-01-01
This book provides a comprehensive introduction to the theory and practice of spherical microphone arrays. It is written for graduate students, researchers and engineers who work with spherical microphone arrays in a wide range of applications. The first two chapters provide the reader with the necessary mathematical and physical background, including an introduction to the spherical Fourier transform and the formulation of plane-wave sound fields in the spherical harmonic domain. The third chapter covers the theory of spatial sampling, employed when selecting the positions of microphones to sample sound pressure functions in space. Subsequent chapters present various spherical array configurations, including the popular rigid-sphere-based configuration. Beamforming (spatial filtering) in the spherical harmonics domain, including axis-symmetric beamforming, and the performance measures of directivity index and white noise gain are introduced, and a range of optimal beamformers for spherical arrays, includi...
Energy Technology Data Exchange (ETDEWEB)
Maprelian, Eduardo; Torres, Walmir M.; Prado, Adelk C.; Umbehaun, Pedro E.; Franca, Renato L.; Santos, Samuel C.; Macedo, Luiz A.; Sabundjian, Gaiane, E-mail: emaprel@ipen.br, E-mail: wmtorres@ipen.br, E-mail: acprado@ipen.br, E-mail: umbehaun@ipen.br, E-mail: rlfranca@ipen.br, E-mail: samuelcs@ipen.br, E-mail: lamacedo@ipen.br, E-mail: gdjian@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SO (Brazil)
2015-07-01
The three basic safety functions of Research Reactors (RR) are the safe shutdown of the reactor, the proper cooling of the decay heat of the fuel elements and the confinement of radioactive materials. Compared to Nuclear Power Reactors, RR power release is small, yet its three safety functions must be met to ensure the integrity of the reactor. During a loss of coolant accident (LOCA) in pool type RR, partial or complete loss of pool water may occur, with consequent partial or complete uncovering of the fuel assemblies. In such an accident, the decay heat removal safety function must not be compromised. The Test Section for Experimental Simulation of Loss of Coolant Accident (STAR) is in commissioning phase. This test section will provide experimental data on partial and total uncovering of the EC-208 instrumented fuel assembly (IFA) irradiated in the IEA-R1. Experimental results will be useful in validation of computer codes for RR safety analysis, particularly on heat removal efficiency aspects (safety function) in accident conditions. STAR comprises a base on which is installed the IFA, the cylindrical stainless steel hull, the compressed air system for the test section emptying and refilling, and the instrumentation for temperature and level measurements. The commissioning tests or pre-operational check, consist of several preliminary tests to verify experimental procedures, the difficulties during assembling of STAR in the pool, the difficulties in control the emptying and refilling velocities, as well as, the repeatability capacity, tests of equipment, valves and systems and tests of instrumentation and data acquisition system. Safety, accuracy and easiness of operation will be checked. (author)
Investigation of spherical and concentric mechanism of compound droplets
Directory of Open Access Journals (Sweden)
Meifang Liu
2016-07-01
Full Text Available Polymer shells with high sphericity and uniform wall thickness are always needed in the inertial confined fusion (ICF experiments. Driven by the need to control the shape of water-in-oil (W1/O compound droplets, the effects of the density matching level, the interfacial tension and the rotation speed of the continuing fluid field on the sphericity and wall thickness uniformity of the resulting polymer shells were investigated and the spherical and concentric mechanisms were also discussed. The centering of W1/O compound droplets, the location and movement of W1/O compound droplets in the external phase (W2 were significantly affected by the density matching level of the key stage and the rotation speed of the continuing fluid field. Therefore, by optimizing the density matching level and rotation speed, the batch yield of polystyrene (PS shells with high sphericity and uniform wall thickness increased. Moreover, the sphericity also increased by raising the oil/water (O/W2 interfacial tension, which drove a droplet to be spherical. The experimental results show that the spherical driving force is from the interfacial tension affected by the two relative phases, while the concentric driving force, as a resultant force, is not only affected by the three phases, but also by the continuing fluid field. The understanding of spherical and concentric mechanism can provide some guidance for preparing polymer shells with high sphericity and uniform wall thickness.
International Nuclear Information System (INIS)
Barashenkov, V.S.; Puzynin, I.V.; Sisakyan, A.N.; Polanski, A.
1999-01-01
We present a Plutonium Based Energy Amplifier Testing Concept, which employs a plutonium subcritical assembly and a 660 MeV proton accelerator operating in the JINR Laboratory of Nuclear Problems. Fuel designed for the pulsed neutron source IREN (Laboratory of Neutron Physics, JINR) will be adopted for the core of the assembly. To make the present conceptual design of the Plutonium Energy Amplifier we have chosen a nominal unit capacity of 20 kW (thermal). This corresponds to the multiplication coefficient K eff ranging between 0.94 and 0.95 and the energetic gain about 20. Accelerated current is in the range of 1-1.6μA
Laurinavichius, K S
1998-01-01
Experimental Investigation Of Microbially Induced Corrosion Of Test Samples And Effect Of Self-assembled Hydrophobic Monolayers. Exposure Of Test Samples To Continuous Microbial Cultures, Chemical Analysis, And Biochemical Studies
Evolution of the spherical clusters
International Nuclear Information System (INIS)
Surdin, V.G.
1978-01-01
The possible processes of the Galaxy spherical clusters formation and evolution are described on a popular level. The orbits of spherical cluster motion and their spatial velocities are determined. Given are the distrbutions of spherical cluster stars according to their velocities and the observed distribution of spherical clusters in the area of the Galaxy slow evolution. The dissipation and dynamic friction processes destructing clusters with the mass less than 10 4 of solar mass and bringing about the reduction of clusters in the Galaxy are considered. The paradox of forming mainly X-ray sources in spherical clusters is explained. The schematic image of possible ways of forming X-ray sources in spherical clusters is given
Spherical tokamak development in Brazil
Energy Technology Data Exchange (ETDEWEB)
Ludwig, Gerson Otto; Bosco, Edson Del; Ferreira, Julio Guimaraes [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Plasma] (and others)
2003-07-01
The general characteristics of spherical tokamaks, or spherical tori, with a brief view of work in this area already performed or in progress at several institutions worldwide are described. The paper presents also the steps in the development of the ETE (Experiment Tokamak spheric) project, its research program, technical characteristics and operating conditions as of December, 2002 a the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)
Spherical tokamak development in Brazil
International Nuclear Information System (INIS)
Ludwig, Gerson Otto; Bosco, Edson Del; Ferreira, Julio Guimaraes
2003-01-01
The general characteristics of spherical tokamaks, or spherical tori, with a brief view of work in this area already performed or in progress at several institutions worldwide are described. The paper presents also the steps in the development of the ETE (Experiment Tokamak spheric) project, its research program, technical characteristics and operating conditions as of December, 2002 a the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)
Particle Entrainment in Spherical-Cap Wakes
Energy Technology Data Exchange (ETDEWEB)
Warncke, Norbert G W; Delfos, Rene; Ooms, Gijs; Westerweel, Jerry, E-mail: n.g.w.warncke@tudelft.nl [Laboratory for Aero- and Hydrodynamics, Delft University of Technology (Netherlands)
2011-12-22
In this work we study the preferential concentration of small particles in the turbulent wake behind a spherical-cap object. We present a model predicting the mean particle concentration in the near-wake as a function of the characteristic Stokes number of the problem, the turbulence level and the Froude number. We compare the model with our experimental results on this flow, measured in a vertical water tunnel.
All silicon waveguide spherical microcavity coupler device.
Xifré-Pérez, E; Domenech, J D; Fenollosa, R; Muñoz, P; Capmany, J; Meseguer, F
2011-02-14
A coupler based on silicon spherical microcavities coupled to silicon waveguides for telecom wavelengths is presented. The light scattered by the microcavity is detected and analyzed as a function of the wavelength. The transmittance signal through the waveguide is strongly attenuated (up to 25 dB) at wavelengths corresponding to the Mie resonances of the microcavity. The coupling between the microcavity and the waveguide is experimentally demonstrated and theoretically modeled with the help of FDTD calculations.
Spherical grating spectrometers
O'Donoghue, Darragh; Clemens, J. Christopher
2014-07-01
We describe designs for spectrometers employing convex dispersers. The Offner spectrometer was the first such instrument; it has almost exclusively been employed on satellite platforms, and has had little impact on ground-based instruments. We have learned how to fabricate curved Volume Phase Holographic (VPH) gratings and, in contrast to the planar gratings of traditional spectrometers, describe how such devices can be used in optical/infrared spectrometers designed specifically for curved diffraction gratings. Volume Phase Holographic gratings are highly efficient compared to conventional surface relief gratings; they have become the disperser of choice in optical / NIR spectrometers. The advantage of spectrometers with curved VPH dispersers is the very small number of optical elements used (the simplest comprising a grating and a spherical mirror), as well as illumination of mirrors off axis, resulting in greater efficiency and reduction in size. We describe a "Half Offner" spectrometer, an even simpler version of the Offner spectrometer. We present an entirely novel design, the Spherical Transmission Grating Spectrometer (STGS), and discuss exemplary applications, including a design for a double-beam spectrometer without any requirement for a dichroic. This paradigm change in spectrometer design offers an alternative to all-refractive astronomical spectrometer designs, using expensive, fragile lens elements fabricated from CaF2 or even more exotic materials. The unobscured mirror layout avoids a major drawback of the previous generation of catadioptric spectrometer designs. We describe laboratory measurements of the efficiency and image quality of a curved VPH grating in a STGS design, demonstrating, simultaneously, efficiency comparable to planar VPH gratings along with good image quality. The stage is now set for construction of a prototype instrument with impressive performance.
Energy Technology Data Exchange (ETDEWEB)
Giust, Flavio, E-mail: flavio.giust@axpo.c [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Axpo Kernenergie AG, Parkstrasse 23, CH-5401 Baden (Switzerland); Grimm, Peter [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Chawla, Rakesh [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland)
2010-12-15
Total fission rate measurements have been performed on full-size BWR fuel assemblies of type SVEA-96+ in the zero power reactor PROTEUS at the Paul Scherrer Institute. This paper presents comparisons of reconstructed 2D pin fission rates from nodal diffusion calculations to the experimental results in two configurations: one 'regular' (I-1A) and the other 'controlled' (I-2A). Both configurations consist of an array of 3 x 3 SVEA-96+ fuel assemblies moderated with light water at 20 {sup o}C. In configuration I-2A, an L-shaped hafnium control blade (half of a real cruciform blade) is inserted adjacent to the north-west corner of the central fuel assembly. To minimise the impact of the surroundings, all measurements were done in fuel pins belonging to the central assembly. The 3 x 3 experimental configuration (test zone) was modelled using the core monitoring and design tools that are applied at the Leibstadt Nuclear Power Plant (KKL). These are the 2D transport code HELIOS, used for the cross-section generation, and the 3D, 2-group nodal diffusion code PRESTO-2. The exterior is represented, in the axial and radial directions, by 2-group partial current ratios (PCRs) calculated at the test zone boundary using a 3D Monte Carlo (MCNPX) model of the whole PROTEUS reactor. Sensitivity cases are analysed to show the impact of changes in the 2D lattice modelling on the calculated fission rate distribution and reactivity. Further, the effects of variations in the test zone boundary PCRs and their behaviour in energy are investigated. For the test zone configuration without control blade, the pin-power reconstruction methodology delivers the same level of accuracy as the 2D transport calculations. On the other hand, larger deviations that are inherent to the use of reflected geometry in the lattice calculations are observed for the configuration with the control blade inserted. In the basic (reference) simulation cases, the calculated-to-experimental (C
Dynamic behaviour of diagnostic assemblies
International Nuclear Information System (INIS)
Pecinka, L.
1980-01-01
The methodology is shown of calculating the frequency spectrum of a diagnostic assembly. The oscillations of the assembly as a whole, of a fuel rod bundle, the assembly jacket and of the individual rods in the bundle were considered. The manufacture is suggested of a model assembly which would be used for testing forced vibrations using an experimental water loop. (M.S.)
First results of spherical GEMs
Pinto, Serge Duarte; Brock, Ian; Croci, Gabriele; David, Eric; de Oliveira, Rui; Ropelewski, Leszek; van Stenis, Miranda; Taureg, Hans; Villa, Marco
2010-01-01
We developed a method to make GEM foils with a spherical geometry. Tests of this procedure and with the resulting spherical GEMs are presented. Together with a spherical drift electrode, a spherical conversion gap can be formed. This eliminates the parallax error for detection of x-rays, neutrons or UV photons when a gaseous converter is used. This parallax error limits the spatial resolution at wide scattering angles. Besides spherical GEMs, we have developed curved spacers to maintain accurate spacing, and a conical field cage to prevent edge distortion of the radial drift field up to the limit of the angular acceptance of the detector. With these components first tests are done in a setup with a spherical entrance window but a planar readout structure; results will be presented and discussed. A flat readout structure poses difficulties, however. Therefore we will show advanced plans to make a prototype of an entirely spherical double-GEM detector, including a spherical 2D readout structure. This detector w...
Spherical Torus Center Stack Design
International Nuclear Information System (INIS)
C. Neumeyer; P. Heitzenroeder; C. Kessel; M. Ono; M. Peng; J. Schmidt; R. Woolley; I. Zatz
2002-01-01
The low aspect ratio spherical torus (ST) configuration requires that the center stack design be optimized within a limited available space, using materials within their established allowables. This paper presents center stack design methods developed by the National Spherical Torus Experiment (NSTX) Project Team during the initial design of NSTX, and more recently for studies of a possible next-step ST (NSST) device
International Nuclear Information System (INIS)
Burlon, Alejandro A.; Valda, Alejandro A.; Girola, Santiago; Minsky, Daniel M.; Kreiner, Andres J.
2010-01-01
In the frame of the construction of a Tandem Electrostatic Quadrupole Accelerator facility devoted to the Accelerator-Based Boron Neutron Capture Therapy, a Beam Shaping Assembly has been characterized by means of Monte-Carlo simulations and measurements. The neutrons were generated via the 7 Li(p, n) 7 Be reaction by irradiating a thick LiF target with a 2.3 MeV proton beam delivered by the TANDAR accelerator at CNEA. The emerging neutron flux was measured by means of activation foils while the beam quality and directionality was evaluated by means of Monte Carlo simulations. The parameters show compliance with those suggested by IAEA. Finally, an improvement adding a beam collimator has been evaluated.
Energy Technology Data Exchange (ETDEWEB)
Dowker, J S, E-mail: dowker@man.ac.uk [Theory Group, School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom)
2011-08-07
A piston is introduced into a spherical lune Casimir cavity turning it into two adjacent lunes separated by the (hemispherical) piston. On the basis of zeta-function regularization, the vacuum energy of the arrangement is finite for conformal propagation in spacetime. For even spheres this energy is independent of the angle of the lune. For odd dimensions it is shown that for all Neumann, or all Dirichlet, boundary conditions the piston is repelled or attracted by the nearest wall if d = 3, 7, ... or if d = 1, 5, ... , respectively. For hybrid N-D conditions these requirements are switched. If a mass is added, divergences arise which render the model suspect. The analysis, however, is relatively straightforward and involves the Barnes zeta function. The extension to finite temperatures is made and it is shown that for the 3, 7, ... series of odd spheres, the repulsion by the walls continues but that, above a certain temperature, the free energy acquires two minima symmetrically placed about the midpoint.
International Nuclear Information System (INIS)
Dowker, J S
2011-01-01
A piston is introduced into a spherical lune Casimir cavity turning it into two adjacent lunes separated by the (hemispherical) piston. On the basis of zeta-function regularization, the vacuum energy of the arrangement is finite for conformal propagation in spacetime. For even spheres this energy is independent of the angle of the lune. For odd dimensions it is shown that for all Neumann, or all Dirichlet, boundary conditions the piston is repelled or attracted by the nearest wall if d = 3, 7, ... or if d = 1, 5, ... , respectively. For hybrid N-D conditions these requirements are switched. If a mass is added, divergences arise which render the model suspect. The analysis, however, is relatively straightforward and involves the Barnes zeta function. The extension to finite temperatures is made and it is shown that for the 3, 7, ... series of odd spheres, the repulsion by the walls continues but that, above a certain temperature, the free energy acquires two minima symmetrically placed about the midpoint.
Energy Technology Data Exchange (ETDEWEB)
Giust, F. D. [Axpo Kernenergie, Parkstrasse 23, CH-5401 Baden (Switzerland); Swiss Federal Inst. of Technology EPFL, CH-1015 Lausanne (Switzerland); Grimm, P. [Paul Scherrer Inst., CH-5232 Villigen (Switzerland); Chawla, R. [Paul Scherrer Inst., CH-5232 Villigen (Switzerland); Swiss Federal Inst. of Technology (EPFL), CH-1015 Lausanne (Switzerland)
2012-07-01
Total fission rate measurements have been performed on full-size BWR fuel assemblies of type SVEA-96 Optima2 in the framework of Phase III of the LWR-PROTEUS experimental program at the Paul Scherrer Inst.. This paper presents comparisons of calculated, nodal reconstructed, pin-wise total-fission rate distributions with experimental results. Radial comparisons have been performed for the three sections of the assembly (96, 92 and 84 fuel pins), while three-dimensional effects have been investigated at pellet-level for the two transition regions, i.e. the tips of the short (1/3) and long (2/3) partial length rods. The test zone has been modeled using two different code systems: HELIOS/PRESTO-2 and CASMO-5/SIMULATE-5. The first is presently used for core monitoring and design at the Leibstadt Nuclear Power Plant (KKL). The second represents the most recent generation of the widely applied CASMO/SIMULATE system. For representing the PROTEUS test-zone boundaries, Partial Current Ratios (PCRs) - derived from a 3D MCNPX model of the entire reactor - have been applied to the PRESTO-2 and SIMULATE-5 models in the form of 2- and 5-group diagonal albedo matrices, respectively. The MCNPX results have also served as a reference, high-order transport solution in the calculation/experiment comparisons. It is shown that the performance of the nodal methodologies in predicting the global distribution of the total-fission rate is very satisfactory. Considering the various radial comparisons, the standard deviations of the calculated/experimental (C/E) distributions do not exceed 1.9% for any of the three methodologies - PRESTO-2, SIMULATE-5 and MCNPX. For the three-dimensional comparisons at pellet-level, the corresponding standard deviations are 2.7%, 2.0% and 2.1%, respectively. (authors)
Models for randomly distributed nanoscopic domains on spherical vesicles
Anghel, Vinicius N. P.; Bolmatov, Dima; Katsaras, John
2018-06-01
The existence of lipid domains in the plasma membrane of biological systems has proven controversial, primarily due to their nanoscopic size—a length scale difficult to interrogate with most commonly used experimental techniques. Scattering techniques have recently proven capable of studying nanoscopic lipid domains populating spherical vesicles. However, the development of analytical methods able of predicting and analyzing domain pair correlations from such experiments has not kept pace. Here, we developed models for the random distribution of monodisperse, circular nanoscopic domains averaged on the surface of a spherical vesicle. Specifically, the models take into account (i) intradomain correlations corresponding to form factors and interdomain correlations corresponding to pair distribution functions, and (ii) the analytical computation of interdomain correlations for cases of two and three domains on a spherical vesicle. In the case of more than three domains, these correlations are treated either by Monte Carlo simulations or by spherical analogs of the Ornstein-Zernike and Percus-Yevick (PY) equations. Importantly, the spherical analog of the PY equation works best in the case of nanoscopic size domains, a length scale that is mostly inaccessible by experimental approaches such as, for example, fluorescent techniques and optical microscopies. The analytical form factors and structure factors of nanoscopic domains populating a spherical vesicle provide a new and important framework for the quantitative analysis of experimental data from commonly studied phase-separated vesicles used in a wide range of biophysical studies.
International Nuclear Information System (INIS)
Blaise, Patrick; Vidal, Jean-Francois; Santamarina, Alain
2009-01-01
This paper details the validation of Gd-poisoned 17x17 PWR lattices, through several configurations of the CAMELEON experimental program, by using the newly qualified REL2005 French code package. After a general presentation of the CAMELEON program that took place in the EOLE critical Facility in Cadarache, one describes the new REL2005 code package relying on the deterministic transport code APOLLO2.8 based on characteristics method (MOC), and its new CEA2005 library based on the latest JEFF-3.1.1 nuclear data evaluation. For critical masses, the average Calculation-to-Experiment C/E's on the k eff are (136 ± 80) pcm and (300 ± 76) pcm for the reference 281 groups MOC and optimized 26 groups MOC schemes respectively. These values include also a drastic improvement of about 250 pcm due to the change in the library from JEF2.2 to JEFF3.1. For pin-by-pin radial power distributions, reference and REL2005 results are very close, with maximum discrepancies of the order of 2%, i.e., in the experimental uncertainty limits. The Optimized REL2005 code package allows to predict the reactivity worth of the Gd-clusters (averaged on 9 experimental configurations) to be C/E Δρ(Gd clusters) = +1.3% ± 2.3%. (author)
International Nuclear Information System (INIS)
Jia, Juanjuan; Kara, Abdelkader; Pasquali, Luca; Bendounan, Azzedine; Sirotti, Fausto; Esaulov, Vladimir A.
2015-01-01
Characteristic core level binding energies (CLBEs) are regularly used to infer the modes of molecular adsorption: orientation, organization, and dissociation processes. Here, we focus on a largely debated situation regarding CLBEs in the case of chalcogen atom bearing molecules. For a thiol, this concerns the case when the CLBE of a thiolate sulfur at an adsorption site can be interpreted alternatively as due to atomic adsorption of a S atom, resulting from dissociation. Results of an investigation of the characteristics of thiol self-assembled monolayers (SAMs) obtained by vacuum evaporative adsorption are presented along with core level binding energy calculations. Thiol ended SAMs of 1,4-benzenedimethanethiol (BDMT) obtained by evaporation on Au display an unconventional CLBE structure at about 161.25 eV, which is close to a known CLBE of a S atom on Au. Adsorption and CLBE calculations for sulfur atoms and BDMT molecules are reported and allow delineating trends as a function of chemisorption on hollow, bridge, and atop sites and including the presence of adatoms. These calculations suggest that the 161.25 eV peak is due to an alternative adsorption site, which could be associated to an atop configuration. Therefore, this may be an alternative interpretation, different from the one involving the adsorption of atomic sulfur resulting from the dissociation process of the S–C bond. Calculated differences in S(2p) CLBEs for free BDMT molecules, SH group sulfur on top of the SAM, and disulfide are also reported to clarify possible errors in assignments
Energy Technology Data Exchange (ETDEWEB)
Jia, Juanjuan [Institut des Sciences Moléculaires d’Orsay, Université-Paris Sud, 91405 Orsay (France); CNRS, UMR 8214, Institut des Sciences Moléculaires d’Orsay, Orsay ISMO, Bâtiment 351, Université Paris Sud, 91405 Orsay (France); Kara, Abdelkader, E-mail: abdelkader.kara@ucf.edu, E-mail: vladimir.esaulov@u-psud.fr [Department of Physics, University of Central Florida, Orlando, Florida 32816 (United States); Pasquali, Luca [Dipartimento di Ingegneria “E. Ferrari,” Università di Modena e Reggio Emilia, Via Vignolese 905, 41125 Modena (Italy); IOM-CNR, s.s. 14, Km. 163.5 in AREA Science Park, 34149 Basovizza, Trieste (Italy); Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park 2006 (South Africa); Bendounan, Azzedine; Sirotti, Fausto [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex (France); Esaulov, Vladimir A., E-mail: abdelkader.kara@ucf.edu, E-mail: vladimir.esaulov@u-psud.fr [Institut des Sciences Moléculaires d’Orsay, Université-Paris Sud, 91405 Orsay (France); CNRS, UMR 8214, Institut des Sciences Moléculaires d’Orsay, Orsay ISMO, Bâtiment 351, Université Paris Sud, 91405 Orsay (France); IOM-CNR, s.s. 14, Km. 163.5 in AREA Science Park, 34149 Basovizza, Trieste (Italy)
2015-09-14
Characteristic core level binding energies (CLBEs) are regularly used to infer the modes of molecular adsorption: orientation, organization, and dissociation processes. Here, we focus on a largely debated situation regarding CLBEs in the case of chalcogen atom bearing molecules. For a thiol, this concerns the case when the CLBE of a thiolate sulfur at an adsorption site can be interpreted alternatively as due to atomic adsorption of a S atom, resulting from dissociation. Results of an investigation of the characteristics of thiol self-assembled monolayers (SAMs) obtained by vacuum evaporative adsorption are presented along with core level binding energy calculations. Thiol ended SAMs of 1,4-benzenedimethanethiol (BDMT) obtained by evaporation on Au display an unconventional CLBE structure at about 161.25 eV, which is close to a known CLBE of a S atom on Au. Adsorption and CLBE calculations for sulfur atoms and BDMT molecules are reported and allow delineating trends as a function of chemisorption on hollow, bridge, and atop sites and including the presence of adatoms. These calculations suggest that the 161.25 eV peak is due to an alternative adsorption site, which could be associated to an atop configuration. Therefore, this may be an alternative interpretation, different from the one involving the adsorption of atomic sulfur resulting from the dissociation process of the S–C bond. Calculated differences in S(2p) CLBEs for free BDMT molecules, SH group sulfur on top of the SAM, and disulfide are also reported to clarify possible errors in assignments.
JUST: Joint Upgraded Spherical Tokamak
International Nuclear Information System (INIS)
Azizov, E.A.; Dvorkin, N.Ya.; Filatov, O.G.
1997-01-01
The main goals, ideas and the programme of JUST, spherical tokamak (ST) for the plasma burn investigation, are presented. The place and prospects of JUST in thermonuclear investigations are discussed. (author)
Multi-sensor control for precise assembly of optical components
Directory of Open Access Journals (Sweden)
Ma Li
2014-06-01
Full Text Available In order to perform an optical assembly accurately, a multi-sensor control strategy is developed which includes an attitude measurement system, a vision system, a loss measurement system and a force sensor. A 3-DOF attitude measuring method using linear variable differential transformers (LVDT is designed to adjust the relation of position and attitude between the spherical mirror and the resonator. A micro vision feedback system is set up to extract the light beam and the diaphragm, which can achieve the coarse positioning of the spherical mirror in the optical assembly process. A rapid self-correlation method is presented to analyze the spectrum signal for the fine positioning. In order to prevent the damage of the optical components and realize sealing of the resonator, a hybrid force-position control is constructed to control the contact force of the optical components. The experimental results show that the proposed multi-sensor control strategy succeeds in accomplishing the precise assembly of the optical components, which consists of parallel adjustment, macro coarse adjustment, macro approach, micro fine adjustment, micro approach and optical contact. Therefore, the results validate the multi-sensor control strategy.
Spherical tokamak development in Brazil
International Nuclear Information System (INIS)
Ludwig, G.O.; Del Bosco, E.; Ferreira, J.G.; Berni, L.A.; Oliveira, R.M.; Andrade, M.C.R.; Shibata, C.S.; Ueda, M.; Barroso, J.J.; Castro, P.J.; Barbosa, L.F.W.; Patire Junior, H.; The high-power microwave sources group
2003-01-01
This paper describes the general characteristics of spherical tokamaks, or spherical tori, with a brief overview of work in this area already performed or in progress at several institutions worldwide. The paper presents also the steps in the development of the ETE (Experimento Tokamak Esferico) project, its research program, technical characteristics and operating conditions as of December, 2002 at the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)
Miniaturization of Spherical Magnetodielectric Antennas
DEFF Research Database (Denmark)
Hansen, Troels Vejle
; Arbitrary order of the spherical wave, arbitrary radius of the spherical antenna, as well as arbitrarily large core permeability and/or permittivity, given an inversely proportional frequency variation of the imaginary part(s) and an arbitrary dispersion of the real part(s) - thus describing both lossless...... with a magnetic loss tangent of 1 and relative permeability of 300 yield Q/e equal 65% of the Chu lower bound, with a simultaneous e of 71%....
Spherical tokamak development in Brazil
Energy Technology Data Exchange (ETDEWEB)
Ludwig, G.O.; Del Bosco, E.; Ferreira, J.G.; Berni, L.A.; Oliveira, R.M.; Andrade, M.C.R.; Shibata, C.S.; Ueda, M.; Barroso, J.J.; Castro, P.J. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Plasma; Barbosa, L.F.W. [Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, SP (Brazil). Faculdade de Engenharia, Arquitetura e Urbanismo; Patire Junior, H. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Div. de Mecanica Espacial e Controle; The high-power microwave sources group
2003-12-01
This paper describes the general characteristics of spherical tokamaks, or spherical tori, with a brief overview of work in this area already performed or in progress at several institutions worldwide. The paper presents also the steps in the development of the ETE (Experimento Tokamak Esferico) project, its research program, technical characteristics and operating conditions as of December, 2002 at the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)
Ultrasmooth, Highly Spherical Monocrystalline Gold Particles for Precision Plasmonics
Lee, You-Jin
2013-12-23
Ultrasmooth, highly spherical monocrystalline gold particles were prepared by a cyclic process of slow growth followed by slow chemical etching, which selectively removes edges and vertices. The etching process effectively makes the surface tension isotropic, so that spheres are favored under quasi-static conditions. It is scalable up to particle sizes of 200 nm or more. The resulting spherical crystals display uniform scattering spectra and consistent optical coupling at small separations, even showing Fano-like resonances in small clusters. The high monodispersity of the particles we demonstrate should facilitate the self-assembly of nanoparticle clusters with uniform optical resonances, which could in turn be used to fabricate optical metafluids. Narrow size distributions are required to control not only the spectral features but also the morphology and yield of clusters in certain assembly schemes. © 2013 American Chemical Society.
Spherical aggregates composed of gold nanoparticles
International Nuclear Information System (INIS)
Chen, C-C; Kuo, P-L; Cheng, Y-C
2009-01-01
Alkylated triethylenetetramine (C12E3) was synthesized and used as both a reductant in the preparation of gold nanoparticles by the reduction of HAuCl 4 and a stabilizer in the subsequent self-assembly of the gold nanoparticles. In acidic aqueous solution, spherical aggregates (with a diameter of about 202 ± 22 nm) of gold nanoparticles (with the mean diameter of ∼18.7 nm) were formed. The anion-induced ammonium adsorption of the alkylated amines on the gold nanoparticles was considered to provide the electrostatic repulsion and steric hindrance between the gold nanoparticles, which constituted the barrier that prevented the individual particles from coagulating. However, as the amino groups became deprotonated with increasing pH, the ammonium adsorption was weakened, and the amino groups were desorbed from the gold surface, resulting in discrete gold particles. The results indicate that the morphology of the reduced gold nanoparticles is controllable through pH-'tunable' aggregation under the mediation of the amino groups of alkylated amine to create spherical microstructures.
Saleem, Mohammed; Morlot, Sandrine; Hohendahl, Annika; Manzi, John; Lenz, Martin; Roux, Aurélien
2015-02-01
In endocytosis, scaffolding is one of the mechanisms to create membrane curvature by moulding the membrane into the spherical shape of the clathrin cage. However, the impact of membrane elastic parameters on the assembly and shape of clathrin lattices has never been experimentally evaluated. Here, we show that membrane tension opposes clathrin polymerization. We reconstitute clathrin budding in vitro with giant unilamellar vesicles (GUVs), purified adaptors and clathrin. By changing the osmotic conditions, we find that clathrin coats cause extensive budding of GUVs under low membrane tension while polymerizing into shallow pits under moderate tension. High tension fully inhibits polymerization. Theoretically, we predict the tension values for which transitions between different clathrin coat shapes occur. We measure the changes in membrane tension during clathrin polymerization, and use our theoretical framework to estimate the polymerization energy from these data. Our results show that membrane tension controls clathrin-mediated budding by varying the membrane budding energy.
Turbulence Modulation by Non-Spherical Particles
DEFF Research Database (Denmark)
Mandø, Matthias
This study deals with the interaction between turbulence and non-spherical particles and represents an extension of the modeling framework for particleladen flows. The effect of turbulence on particles is commonly referred to as turbulent dispersion while the effect of particles on the carrier....... This study encompass an outlook on existing work, an experimental study, development of a numerical model and a case study advancing the modeling techniques for pulverized coal combustion to deal with larger non-spherical biomass particles. Firstly, existing knowledge concerning the motion of non......-spherical particles and turbulence modulation are outlined. A complete description of the motion of non-spherical particles is still lacking. However, evidence suggests that the equation of motion for a sphere only represent an asymptotical value for a more general, but yet unformulated, description of the motion...
International Nuclear Information System (INIS)
Kobzar, L.L.; Oleksyuk, D.A.
2001-01-01
The results of experiments executed in RRC 'Kurchatov Institute on the thermal-physical critical facility SVD are presented herein. The experiments modeled the drawing of two fuel rods to each other till touching WWER-1000 reactor in FA. The experimental model is a 7-rod bundle with the heated length of 1 m. The primary goal of experiments was to acquire the quantitative factors of the reduction in the critical heat fluxes as contrasted to the basic model (without disturbances of FA geometry) at the expense of local disturbance of a rod bundle geometry. As it follows from the experiment, the effect of decrease of the critical heat rate depends on combination of regime parameters and it makes 15% in the most unfavorable case (Authors)
Equivalent-spherical-shield neutron dose calculations
International Nuclear Information System (INIS)
Russell, G.J.; Robinson, H.
1988-01-01
Neutron doses through 162-cm-thick spherical shields were calculated to be 1090 and 448 mrem/h for regular and magnetite concrete, respectively. These results bracket the measured data, for reinforced regular concrete, of /approximately/600 mrem/h. The calculated fraction of the high-energy (>20 MeV) dose component also bracketed the experimental data. The measured and calculated doses were for a graphite beam stop bombarded with 100 nA of 800-MeV protons. 6 refs., 2 figs., 1 tab
Ultrasonic calibration assembly
International Nuclear Information System (INIS)
1981-01-01
Ultrasonic transducers for in-service inspection of nuclear reactor vessels have several problems associated with them which this invention seeks to overcome. The first is that of calibration or referencing a zero start point for the vertical axis of transducer movement to locate a weld defect. The second is that of verifying the positioning (vertically or at a predetermined angle). Thirdly there is the problem of ascertaining the speed per unit distance in the operating medium of the transducer beam prior to the actual inspection. The apparatus described is a calibration assembly which includes a fixed, generally spherical body having a surface for reflecting an ultrasonic beam from one of the transducers which can be moved until the reflection from the spherical body is the highest amplitude return signal indicating radial alignment from the body. (U.K.)
International Nuclear Information System (INIS)
Kanamori, Naokazu; Nakahira, Masataka; Ohkawa, Yoshinao; Tada, Eisuke; Seki, Masahiro
1996-06-01
The reactor core of the International Thermonuclear Experimental Reactor (ITER) is assembled with a number of large and asymmetric components within a tight tolerance in order to assure the structural integrity for various loads and to provide the tritium confinement. In addition, the assembly procedure should be compatible with remote operation since the core structures will be activated by 14-MeV neutrons once it starts operation and thus personal access will be prohibited. Accordingly, the assembly procedure and tool design are quite essential and should be designed from the beginning to facilitate remote operation. According to the ITER Design Task Agreement, the Japan Atomic Energy Research Institute (JAERI) has performed design study to develop the assembly procedures and associated tool design for the ITER tokamak assembly. This report describes outlines of the assembly tools and the remaining issues obtained in this design study. (author)
Spherical Demons: Fast Surface Registration
Yeo, B.T. Thomas; Sabuncu, Mert; Vercauteren, Tom; Ayache, Nicholas; Fischl, Bruce; Golland, Polina
2009-01-01
We present the fast Spherical Demons algorithm for registering two spherical images. By exploiting spherical vector spline interpolation theory, we show that a large class of regularizers for the modified demons objective function can be efficiently implemented on the sphere using convolution. Based on the one parameter subgroups of diffeomorphisms, the resulting registration is diffeomorphic and fast – registration of two cortical mesh models with more than 100k nodes takes less than 5 minutes, comparable to the fastest surface registration algorithms. Moreover, the accuracy of our method compares favorably to the popular FreeSurfer registration algorithm. We validate the technique in two different settings: (1) parcellation in a set of in-vivo cortical surfaces and (2) Brodmann area localization in ex-vivo cortical surfaces. PMID:18979813
DellaCorte, Christopher; Jefferson, Michael
2015-01-01
NASA Glenn Research Center and the Kamatics subsidiary of the Kaman Corporation conducted the experimental evaluation of spherical sliding bearings made with 60NiTi inner races. The goal of the project was to assess the feasibility of manufacturing lightweight, corrosion resistant bearings utilizing 60NiTi for aerospace and industrial applications. NASA produced the bearings in collaboration with Abbott Ball Corporation and Kamatics fabricated bearing assemblies utilizing their standard reinforced polymer liner material. The assembled bearings were tested in oscillatory motion at a load of 4.54kN (10,000 lb), according to the requirements of the plain bearing specification SAE AS81820. Several test bearings were exposed to hydraulic fluid or aircraft deicing fluid prior to and during testing. The results show that the 60NiTi bearings exhibit tribological performance comparable to conventional stainless steel (440C) bearings. Further, exposure of 60NiTi bearings to the contaminant fluids had no apparent performance effect. It is concluded that 60NiTi is a feasible bearing material for aerospace and industrial spherical bearing applications.
Lin, Yali; Yang, Yujie; Shan, Yuwei; Gong, Lingli; Chen, Jingzhi; Li, Sensen; Chen, Lujian
2017-01-01
Cholesteric liquid crystals (CLCs) exhibit selective Bragg reflections of circularly polarized (CP) light owing to their spontaneous self-assembly abilities into periodic helical structures. Photonic cross-communication patterns could be generated toward potential security applications by spherical cholesteric liquid crystal (CLC) structures. To endow these optical patterns with tunability, we fabricated spherical CLC Bragg reflectors in the shape of microshells by glass-capillary microfluidi...
Babcock and Wilcox plate fabrication experience with uranium silicide spherical fuel
International Nuclear Information System (INIS)
Todd, Lawrence E.; Pace, Brett W.
1996-01-01
This report is written to present the fuel fabrication experience of Babcock and Wilcox using atomized spherical uranium silicide powder. The intent is to demonstrate the ability to fabricate fuel plates using spherical powder and to provide useful information proceeding into the next phase of work using this type of fuel. The limited quantity of resources- spherical powder and time, did not allow for much process optimizing in this work scope. However, the information contained within provides optimism for the future of spherical uranium silicide fuel plate fabrication at Babcock and Wilcox.The success of assembling fuel elements with spherical powder will enable Babcock and Wilcox to reduce overall costs to its customers while still maintaining our reputation for providing high quality research and test reactor products. (author)
Directory of Open Access Journals (Sweden)
Weixin Xu
Full Text Available The propensity of amyloid-β (Aβ peptide to self-assemble into highly ordered amyloid structures lies at the core of their accumulation in the brain during Alzheimer's disease. By using all-atom explicit solvent replica exchange molecular dynamics simulations, we elucidated at the atomic level the intrinsic determinants of the pH-dependent dimerization of the central hydrophobic segment Aβ(12-24 and related these with the propensity to form amyloid fibrils measured by experimental tools such as atomic force microscopy and fluorescence. The process of Aβ(12-24 dimerization was evaluated in terms of free energy landscape, side-chain two-dimensional contact probability maps, β-sheet registries, potential mean force as a function of inter-chain distances, secondary structure development and radial solvation distributions. We showed that dimerization is a key event in Aβ(12-24 amyloid formation; it is highly prompted in the order of pH 5.0>2.9>>8.4 and determines further amyloid growth. The dimerization is governed by a dynamic interplay of hydrophobic, electrostatic and solvation interactions permitting some variability of β-sheets at each pH. These results provide atomistic insight into the complex process of molecular recognition detrimental for amyloid growth and pave the way for better understanding of the molecular basis of amyloid diseases.
Trapped surfaces in spherical stars
International Nuclear Information System (INIS)
Bizon, P.; Malec, E.; O'Murchadha, N.
1988-01-01
We give necessary and sufficient conditions for the existence of trapped surfaces in spherically symmetric spacetimes. These conditions show that the formation of trapped surfaces depends on both the degree of concentration and the average flow of the matter. The result can be considered as a partial validation of the cosmic-censorship hypothesis
Spherical Pendulum, Actions, and Spin
Richter, Peter H.; Dullin, Holger R.; Waalkens, Holger; Wiersig, Jan
1996-01-01
The classical and quantum mechanics of a spherical pendulum are worked out, including the dynamics of a suspending frame with moment of inertia θ. The presence of two separatrices in the bifurcation diagram of the energy-momentum mapping has its mathematical expression in the hyperelliptic nature of
International Nuclear Information System (INIS)
Yang, J.; Lee, Jim Yang; Too, Heng-Phon; Chow, Gan-Moog; Gan, Leong M.
2006-01-01
The non-specific interaction between single stranded DNA (ssDNA) and 12 nm Pt nanoparticles is investigated in this work. The data show a strong and non-specific interaction between the two which can be exploited for the stabilization of Pt nanoparticles in aqueous solutions. Based on the experimental findings, a non-hybridization based protocol to assemble 17 nm Au and Pt nanoparticles (12 nm cubic and 3.6 nm spherical) by single-stranded DNA was developed. Transmission electron microscopy (TEM) and UV-visible spectroscopy confirmed that Au and Pt nanoparticles could be assembled by the non-specific interaction in an orderly manner. The experimental results also caution against the potential pitfalls in using DNA melting point analysis to infer metal nanoparticle assembly by DNA hybridization
Laplacian eigenmodes for spherical spaces
International Nuclear Information System (INIS)
Lachieze-Rey, M; Caillerie, S
2005-01-01
The possibility that our space is multi-rather than singly-connected has gained renewed interest after the discovery of the low power for the first multipoles of the CMB by WMAP. To test the possibility that our space is a multi-connected spherical space, it is necessary to know the eigenmodes of such spaces. Except for lens and prism space, and to some extent for dodecahedral space, this remains an open problem. Here we derive the eigenmodes of all spherical spaces. For dodecahedral space, the demonstration is much shorter, and the calculation method much simpler than before. We also apply our method to tetrahedric, octahedric and icosahedric spaces. This completes the knowledge of eigenmodes for spherical spaces, and opens the door to new observational tests of the cosmic topology. The vector space V k of the eigenfunctions of the Laplacian on the 3-sphere S 3 , corresponding to the same eigenvalue λ k = -k(k + 2), has dimension (k + 1) 2 . We show that the Wigner functions provide a basis for such a space. Using the properties of the latter, we express the behaviour of a general function of V k under an arbitrary rotation G of SO(4). This offers the possibility of selecting those functions of V k which remain invariant under G. Specifying G to be a generator of the holonomy group of a spherical space X, we give the expression of the vector space V x k of the eigenfunctions of X. We provide a method to calculate the eigenmodes up to an arbitrary order. As an illustration, we give the first modes for the spherical spaces mentioned
Chiral pion dynamics for spherical nucleon bags
International Nuclear Information System (INIS)
Vento, V.; Rho, M.; Nyman, E.M.; Jun, J.H.; Brown, G.E.; CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette
1980-01-01
A chirally symmetric quark-bag model for the nucleon is obtained by introducing an explicit, classical, pion field exterior to the bag. The coupling at the bag surface is determined by the requirement of a conserved axial-vector current. The pion field satisfies equations of motion corresponding to the non-linear sigma-model. We study on this paper the simplified case where the bag and the pion field are spherically symmetric. Corrections due to gluon exchange between the quarks are ignored along with other interactions which split the N- and Δ-masses. The equations of motion for the pion field are solved and we find a substantial pion pressure at the bag surface, along with an attractive contribution to the nucleon self-energy. The total energy of the system, bag plus meson cloud, turns out to be approximately Msub(n)c 2 for a wide range of bag radii, from 1.5 fm down to about 0.5 fm. Introduction of a form factor for the pion would extend the range of possible radii to even smaller values. We propose that the bag with the smallest allowed radius be identified with the 'little bag' discussed before. One surprising result of the paper is that as long as one restricts to spherically symmetric bags, restoring chiral symmetry to the bag model makes the axial-vector current coupling constant gsub(A) to be always too large compared with the experimental value for any bag radius, suggesting a deviation from spherical symmetry for the intrinsic bag wave functions of the 'ground-state' hadrons. (orig.)
Spherical transceivers for ultrafast optical wireless communications
Jin, Xian; Hristovski, Blago A.; Collier, Christopher M.; Geoffroy-Gagnon, Simon; Born, Brandon; Holzman, Jonathan F.
2016-02-01
Optical wireless communications (OWC) offers the potential for high-speed and mobile operation in indoor networks. Such OWC systems often employ a fixed transmitter grid and mobile transceivers, with the mobile transceivers carrying out bi-directional communication via active downlinks (ideally with high-speed signal detection) and passive uplinks (ideally with broad angular retroreflection and high-speed modulation). It can be challenging to integrate all of these bidirectional communication capabilities within the mobile transceivers, however, as there is a simultaneous desire for compact packaging. With this in mind, the work presented here introduces a new form of transceiver for bi-directional OWC systems. The transceiver incorporates radial photoconductive switches (for high-speed signal detection) and a spherical retro-modulator (for broad angular retroreflection and high-speed all-optical modulation). All-optical retromodulation are investigated by way of theoretical models and experimental testing, for spherical retro-modulators comprised of three glasses, N-BK7, N-LASF9, and S-LAH79, having differing levels of refraction and nonlinearity. It is found that the spherical retro-modulator comprised of S-LAH79, with a refractive index of n ≍ 2 and a Kerr nonlinear index of n2 ≍ (1.8 ± 0.1) × 10-15 cm2/W, yields both broad angular retroreflection (over a solid angle of 2π steradians) and ultrafast modulation (over a duration of 120 fs). Such transceivers can become important elements for all-optical implementations in future bi-directional OWC systems.
Spherical subjective refraction with a novel 3D virtual reality based system
Directory of Open Access Journals (Sweden)
Jaume Pujol
2017-01-01
Conclusions: The spherical equivalent obtained with the new experimental system was precise and in good agreement with the classical subjective routine. The algorithm implemented in this new system and its optical configuration has been shown to be a first valid step for spherical error correction in a semiautomated way.
Dobdin, S. Yu.; Usanov, D. A.; Skripal, A. V.
2012-06-01
The experimental results to determine the motion characteristics of oscillations of elastic spherical shell filled under the pneumopulse action have been presented. The required characteristics of motion were determined by analysis of the autodyne signal. The relationship between the parameters of motion of the spherical shell and the internal pressure measured using a contact tonometer has been shown.
Gravitational settling of a highly concentrated system of solid spherical particles
Arkhipov, V. A.; Usanina, A. S.
2017-09-01
In the present paper, we report on the results of an experimental study of the process of gravity sedimentation of a cloud of monodispersed solid spherical particles with initial volume concentration C > 0.03, which was performed in a wide range of Reynolds numbers. An analytical estimate of the settling regimes of spherical particle clouds is presented. A new method for creating a spherical particle cloud with a high concentration of particles is proposed. A qualitative picture of the settling process of a highly concentrated particle cloud under gravity is revealed. A criterial dependence for the drag coefficient of a sedimenting spherical particle cloud as an entity is obtained.
Neutron production in a spherical phantom aboard ISS
International Nuclear Information System (INIS)
Tasbaz, A.; Machrafi, R.
2012-01-01
As part of an ongoing research program on radiation monitoring on International Space Station (ISS) that was established to analyze the radiation exposure levels onboard the ISS using different radiation instruments and a spherical phantom to simulate human body. Monte Carlo transport code was used to simulate the interaction of high energy protons and neutrons with the spherical phantom currently onboard ISS. The phantom has been exposed to individual proton energies and to a spectrum of neutrons. The internal to external neutron flux ratio was calculated and compared to the experimental data, recently, measured on the ISS. (author)
Tungsten--carbide critical assembly
International Nuclear Information System (INIS)
Hansen, G.E.; Paxton, H.C.
1975-06-01
The tungsten--carbide critical assembly mainly consists of three close-fitting spherical shells: a highly enriched uranium shell on the inside, a tungsten--carbide shell surrounding it, and a steel shell on the outside. Ideal critical specifications indicate a rather low computed value of k/sub eff/. Observed and calculated fission-rate distributions for 235 U, 238 U, and 237 Np are compared, and calculated leakage neutrons per fission in various energy groups are given. (U.S.)
Status of National Spherical Torus Experiment (NSTX)*
Ono, Masayuki
2001-10-01
The main aim of National Spherical Torus Experiment (NSTX) is to establish the fusion physics principles of the innovative spherical torus (ST) concept. The NSTX experimental facility has been operating reliably and its capabilities steadily improving. Due to relatively efficient ohmic current drive and benign halo current behavior, the plasma current was increased to 1.4 MA, which is well above the design value of 1 MA. The plasmas at 1 MA are now routinely heated by NBI to the average toroidal beta value of 20 percent range at 3 kG with electrons and ions in the 1-2 keV range. Even with the “L-mode” edge, the energy confinement time can well exceed the so-called L-mode (and even H-mode) scaling values. As a part of ST tool development, High Harmonic Fast Wave (HHFW) heating has demonstrated efficient electron heating with the central electron temperatures reaching 3.7 keV. HHFW induced H-modes have been also observed. For CHI (Coaxial Helicity Injection) non-inductive start-up, CHI discharges of up to 300 kA of toroidal current and 300 msec duration have been produced from zero current using = 25 kA of injected current. The poster presentation will also include the near term NSTX facility upgrade plan.
Rotating field current drive in spherical plasmas
International Nuclear Information System (INIS)
Brotherton-Ratcliffe, D.; Storer, R.G.
1988-01-01
The technique of driving a steady Hall current in plasmas using a rotating magnetic field is studied both numerically and analytically in the approximation of negligible ion flow. A spherical plasma bounded by an insulating wall and immersed in a uniform magnetic field which has both a rotating component (for current drive) and a constant ''vertical'' component (for MHD equilibrium) is considered. The problem is formulated in terms of an expansion of field quantities in vector spherical harmonics. The numerical code SPHERE solves the resulting pseudo-harmonic equations by a multiple shooting technique. The results presented, in addition to being relevant to non-inductive current drive generally, have a direct relevance to the rotamak experiments. For the case of no applied vertical field the steady state toroidal current driven by the rotating field per unit volume of plasma is several times less than in the long cylinder limit for a plasma of the same density, resistivity and radius. The application of a vertical field, which for certain parameter regimes gives rise to a compact torus configuration, improves the current drive dramatically and in many cases gives ''better'' current drive than the long cylinder limit. This result is also predicted by a second order perturbation analysis of the pseudo-harmonic equations. A steady state toroidal field is observed which appears consistent with experimental observations in rotamaks regarding magnitude and spatial dependence. This is an advance over previous analytical theory which predicted an oppositely directed toroidal field of undefined magnitude. (author)
International Nuclear Information System (INIS)
De Leeuw-Gierts, G.; De Leeuw, S.; Gilliam, D.M.
1984-01-01
Three spherical configurations of iron and uranium shells have been studied. The configurations were a 1-cm thick natural uranium shell, a 1-cm thick natural uranium shell with an inner 7-cm thick iron shell and a 1-cm thick natural uranium shell with an inner iron shell of 14-cm thickness. For the measurements, the shells were located at the centre of a hollow cavity, 100-cm in diameter, in the vertical graphite thermal column of the BR1 reactor. The central neutron spectra were calculated by means of the DTF-IV code, using the 208-group KEDAK-3 library, and by means of the ANISN code, using the 171-group VITAMIN-C library. Central neutron spectra, measured by the proton-recoil and 6 Li(n,α)t spectrometry techniques, are compared to the theory between ∼ 100 keV and 5 MeV. Mean fission cross-sections of 240 Pu, 237 Np, 234 U, 235 U, 236 U and 238 U were deduced from the calculations. Their ratios with respect to 238 U are compared to measurements made with NBS dual fission chambers. (Auth.)
Developement of Spherical Polyurethane Beads
Institute of Scientific and Technical Information of China (English)
K. Maeda; H. Ohmori; H. Gyotoku
2005-01-01
@@ 1Results and Discussion We established a new method to produce the spherical polyurethane beads which have narrower distribution of particle size. This narrower distribution was achieved by the polyurethane prepolymer which contains ketimine as a blocked chain-extending agent. Firstly, the prepolymer is dispersed into the aqueous solution containing surfactant. Secondaly, water comes into the inside of prepolymer as oil phase. Thirdly, ketimine is hydrolyzed to amine, and amine reacts with prepolymer immediately to be polyurethane.Our spherical polyurethane beads are very suitable for automotive interior parts especially for instrument panel cover sheet producing under the slush molding method, because of good process ability, excellent durability to the sunlight and mechanical properties at low temperature. See Fig. 1 ,Fig. 2 and Fig. 3 (Page 820).
Contractions of affine spherical varieties
International Nuclear Information System (INIS)
Arzhantsev, I V
1999-01-01
The language of filtrations and contractions is used to describe the class of G-varieties obtainable as the total spaces of the construction of contraction applied to affine spherical varieties, which is well-known in invariant theory. These varieties are local models for arbitrary affine G-varieties of complexity 1 with a one-dimensional categorical quotient. As examples, reductive algebraic semigroups and three-dimensional SL 2 -varieties are considered
Spherical subsystem of galactic radiosources
Energy Technology Data Exchange (ETDEWEB)
Gorshkov, A G; Popov, M V [Moskovskij Gosudarstvennyj Univ. (USSR). Gosudarstvennyj Astronomicheskij Inst. ' ' GAISh' '
1975-05-01
The concentration of statistically complete sampling radiosources of the Ohiof scanning with plane spectra towards the Galaxy centre has been discovered. Quantitative calculations have showed that the sources form a spheric subsystem, which is close in parameters to such old formations in the Galaxy as globular clusters and the RRLsub(YR) type stars. The luminosity of the galaxy spheric subsystem object equals 10/sup 33/ erg/sec, the total number of objects being 7000. The existence of such a subsystem explains s the anomalously by low incline of statistics lgN-lgS in HF scanning PKS (..gamma..-2700Mgz) and the Michigan University scanning (..gamma..=8000Mgz) because the sources of galaxy spheric subsystem make up a considerable share in the total number of sources, especially at high frequencies (50% of sources with a flux greater than a unit of flux per 8000Mgz). It is very probable that the given subsystem consists of the representatives of one of the following class of objects: a) heat sources - the H2H regions with T=10/sup 40/K, Nsub(e)=10/sup 3/, l=1 ps b) supermass black holes with mass M/Mo approximately 10/sup 5/.
Directory of Open Access Journals (Sweden)
Anastasia A. Aksyuk
2011-02-01
Full Text Available Bacteriophages have been a model system to study assembly processes for over half a century. Formation of infectious phage particles involves specific protein-protein and protein-nucleic acid interactions, as well as large conformational changes of assembly precursors. The sequence and molecular mechanisms of phage assembly have been elucidated by a variety of methods. Differences and similarities of assembly processes in several different groups of bacteriophages are discussed in this review. The general principles of phage assembly are applicable to many macromolecular complexes.
International Nuclear Information System (INIS)
Nakatsuka, Masafumi.
1979-01-01
Purpose: To prevent scattering of gaseous fission products released from fuel assemblies stored in an fbr type reactor. Constitution; A cap provided with means capable of storing gas is adapted to amount to the assembly handling head, for example, by way of threading in a storage rack of spent fuel assemblies consisting of a bottom plate, a top plate and an assembly support mechanism. By previously eliminating the gas inside of the assembly and the cap in the storage rack, gaseous fission products upon loading, if released from fuel rods during storage, are stored in the cap and do not scatter in the storage rack. (Horiuchi, T.)
DEFF Research Database (Denmark)
Scheibye-Alsing, Karsten; Hoffmann, S.; Frankel, Annett Maria
2009-01-01
Despite the rapidly increasing number of sequenced and re-sequenced genomes, many issues regarding the computational assembly of large-scale sequencing data have remain unresolved. Computational assembly is crucial in large genome projects as well for the evolving high-throughput technologies and...... in genomic DNA, highly expressed genes and alternative transcripts in EST sequences. We summarize existing comparisons of different assemblers and provide a detailed descriptions and directions for download of assembly programs at: http://genome.ku.dk/resources/assembly/methods.html....
Influence of initial imperfections on ultimate strength of spherical shells
Directory of Open Access Journals (Sweden)
Chang-Li Yu
2017-09-01
Full Text Available Comprehensive consideration regarding influence mechanisms of initial imperfections on ultimate strength of spherical shells is taken to satisfy requirement of deep-sea structural design. The feasibility of innovative numerical procedure that combines welding simulation and non-linear buckling analysis is verified by a good agreement to experimental and theoretical results. Spherical shells with a series of wall thicknesses to radius ratios are studied. Residual stress and deformations from welding process are investigated separately. Variant influence mechanisms are discovered. Residual stress is demonstrated to be influential to stress field and buckling behavior but not to the ultimate strength. Deformations are proved to have a significant impact on ultimate strength. When central angles are less than critical value, concave magnitudes reduce ultimate strengths linearly. However, deformations with central angles above critical value are of much greater harm. Less imperfection susceptibility is found in spherical shells with larger wall thicknesses to radius ratios.
Plane-wave decomposition by spherical-convolution microphone array
Rafaely, Boaz; Park, Munhum
2004-05-01
Reverberant sound fields are widely studied, as they have a significant influence on the acoustic performance of enclosures in a variety of applications. For example, the intelligibility of speech in lecture rooms, the quality of music in auditoria, the noise level in offices, and the production of 3D sound in living rooms are all affected by the enclosed sound field. These sound fields are typically studied through frequency response measurements or statistical measures such as reverberation time, which do not provide detailed spatial information. The aim of the work presented in this seminar is the detailed analysis of reverberant sound fields. A measurement and analysis system based on acoustic theory and signal processing, designed around a spherical microphone array, is presented. Detailed analysis is achieved by decomposition of the sound field into waves, using spherical Fourier transform and spherical convolution. The presentation will include theoretical review, simulation studies, and initial experimental results.
Response distributions of 6LiF and 7LiF thermoluminescence dosimeters in lithium blanket assemblies
International Nuclear Information System (INIS)
Maekawa, Hiroshi; Kusano, Jyo-ichi; Seki, Yasushi
1976-11-01
Measurement of the radiation-heating rate distribution in the fusion blanket is as important as measurement of the fission-rate distribution in a fission reactor. To obtain the information of radiation heating, the response (integral glow value) distributions in pseudo-spherical lithium assemblies with and without a graphite reflector were measured with 6 LiF and 7 LiF TLD's. The measured responses are normalized to values per source neutron. Experimental error is about 35%, and the error in positions of TLD's is about +- 3 mm. The experimental results are compared with those of calculation using RADHEAT code system and ENDF/B-III data file. (auth.)
Saltation movement of large spherical particles
Chara, Z.; Dolansky, J.; Kysela, B.
2017-07-01
The paper presents experimental and numerical investigations of the saltation motion of a large spherical particle in an open channel. The channel bottom was roughed by one layer of glass rods of diameter 6 mm. The plastic spheres of diameter 25.7 mm and density 1160 kgm-3 were fed into the water channel and theirs positions were viewed by a digital camera. Two light sheets were placed above and under the channel, so the flow was simultaneously lighted from the top and the bottom. Only particles centers of which moved through the light sheets were recorded. Using a 2D PIV method the trajectories of the spheres and the velocity maps of the channel flow were analyzed. The Lattice-Boldzmann Method (LBM) was used to simulate the particle motion.
Energy Technology Data Exchange (ETDEWEB)
Ricciardi, G.
2008-10-15
The designing of a pressurized water reactor core subjected to seismic loading, is a major concern of the nuclear industry. We propose, in this PhD report, to establish the global behaviour equations of the core, in term of a porous medium. Local equations of fluid and structure are space averaged on a control volume, thus we define an equivalent fluid and an equivalent structure, of which unknowns are defined on the whole space. The non-linear fuel assemblies behaviour is modelled by a visco-elastic constitutive law. The fluid-structure coupling is accounted for by a body force, the expression of that force is based on empirical formula of fluid forces acting on a tube subject to an axial flow. The resulting equations are solved using a finite element method. A validation of the model, on three experimental device, is proposed. The first one presents two fuel assemblies subjected to axial flow. One of the two fuel assemblies is deviated from its position of equilibrium and released, while the other is at rest. The second one presents a six assemblies row, immersed in water, placed on a shaking table that can simulate seismic loading. Finally, the last one presents nine fuel assemblies network, arranged in a three by three, subject to an axial flow. The displacement of the central fuel assembly is imposed. The simulations are in agreement with the experiments, the model reproduces the influence of the flow of fluid on the dynamics and coupling of the fuel assemblies. (author)
Müller, A.; Urich, D.; Kreck, G.; Metzmacher, M.; Lindner, R.
2018-04-01
The presentation will cover results from an ESA supported investigation to collect lessons learned for mechanism assembly with the focus on quality and contamination requirements verification in exploration projects such as ExoMars.
Spherical near-field antenna measurements — The most accurate antenna measurement technique
DEFF Research Database (Denmark)
Breinbjerg, Olav
2016-01-01
The spherical near-field antenna measurement technique combines several advantages and generally constitutes the most accurate technique for experimental characterization of radiation from antennas. This paper/presentation discusses these advantages, briefly reviews the early history and present...
Hierarchical structures of ZnO spherical particles synthesized solvothermally
Saito, Noriko; Haneda, Hajime
2011-12-01
We review the solvothermal synthesis, using a mixture of ethylene glycol (EG) and water as the solvent, of zinc oxide (ZnO) particles having spherical and flower-like shapes and hierarchical nanostructures. The preparation conditions of the ZnO particles and the microscopic characterization of the morphology are summarized. We found the following three effects of the ratio of EG to water on the formation of hierarchical structures: (i) EG restricts the growth of ZnO microcrystals, (ii) EG promotes the self-assembly of small crystallites into spheroidal particles and (iii) the high water content of EG results in hollow spheres.
WAVEMOTH-FAST SPHERICAL HARMONIC TRANSFORMS BY BUTTERFLY MATRIX COMPRESSION
International Nuclear Information System (INIS)
Seljebotn, D. S.
2012-01-01
We present Wavemoth, an experimental open source code for computing scalar spherical harmonic transforms (SHTs). Such transforms are ubiquitous in astronomical data analysis. Our code performs substantially better than existing publicly available codes owing to improvements on two fronts. First, the computational core is made more efficient by using small amounts of pre-computed data, as well as paying attention to CPU instruction pipelining and cache usage. Second, Wavemoth makes use of a fast and numerically stable algorithm based on compressing a set of linear operators in a pre-computation step. The resulting SHT scales as O(L 2 log 2 L) for the resolution range of practical interest, where L denotes the spherical harmonic truncation degree. For low- and medium-range resolutions, Wavemoth tends to be twice as fast as libpsht, which is the current state-of-the-art implementation for the HEALPix grid. At the resolution of the Planck experiment, L ∼ 4000, Wavemoth is between three and six times faster than libpsht, depending on the computer architecture and the required precision. Because of the experimental nature of the project, only spherical harmonic synthesis is currently supported, although adding support for spherical harmonic analysis should be trivial.
A conceptual design of assembly strategy and dedicated tools for assembly of 40o sector
International Nuclear Information System (INIS)
Park, H.K.; Nam, K.O.; Kim, D.J.; Ahn, H.J.; Lee, J.H.; Im, K.; Shaw, R.
2010-01-01
The International Thermanuclear Experimental Reactor (ITER) tokamak device is composed of 9 vacuum vessel (VV)/toroidal field coils (TFCs)/vacuum vessel thermal shields (VVTS) 40 o sectors. Each VV/TFCs/VVTS 40 o sector is made up of one 40 o VV, two 20 o TFCs and associated VVTS segments. The 40 o sectors are sub-assembled at assembly hall respectively and then nine 40 o sectors sub-assembled at assembly hall are finally assembled at tokamak in-pit hall. The assembly strategy and tools for the 40 o sector sub-assembly and final assembly should be developed to satisfy the basic assembly requirements of the ITER tokamak device. Accordingly, the purpose-built assembly tools should be designed and manufactured considering assembly plan, available space, cost, safety, easy operation, efficient maintenance, and so on. The 40 o sector assembly tools are classified into 2 groups. One group is the sub-assembly tools including upending tool, lifting tool, sub-assembly tool, VV supports and bracing tools used at assembly hall and the other group is the in-pit assembly tools including lifting tool, central column, radial beams and their supports. This paper describes the current status of the assembly strategy and major tools for the VV/TFCs/VVTS 40 o sector assembly at in-pit hall and assembly hall. The conceptual design of the major assembly tools and assembly process at assembly hall and tokamak in-pit hall are presented also.
Cooperative effects in spherical spasers
DEFF Research Database (Denmark)
Bordo, Vladimir
2017-01-01
A fully analytical semiclassical theory of cooperative optical processes which occur in an ensemble of molecules embedded in a spherical core-shell nanoparticle is developed from first principles. Both the plasmonic Dicke effect and spaser generation are investigated for the designs in which...... a shell/core contains an arbitrarily large number of active molecules in the vicinity of a metallic core/shell. An essential aspect of the theory is an ab initio account of the feedback from the core/shell boundaries which significantly modifies the molecular dynamics. The theory provides rigorous, albeit...
Spherical bodies of constant width
Lassak, Marek; Musielak, Michał
2018-01-01
The intersection $L$ of two different non-opposite hemispheres $G$ and $H$ of a $d$-dimensional sphere $S^d$ is called a lune. By the thickness of $L$ we mean the distance of the centers of the $(d-1)$-dimensional hemispheres bounding $L$. For a hemisphere $G$ supporting a %spherical convex body $C \\subset S^d$ we define ${\\rm width}_G(C)$ as the thickness of the narrowest lune or lunes of the form $G \\cap H$ containing $C$. If ${\\rm width}_G(C) =w$ for every hemisphere $G$ supporting $C$, we...
International Nuclear Information System (INIS)
Ionescu-Pallas, N.; Vlad, V.I.
1999-01-01
The spectrum of black body radiation at the absolute temperature T, in an ideal spherical cavity of radius R, is studied. The departures from the classical predictions of Planck's theory, due to the discrete energies of the radiation quanta confined inside the cavity, depend on the adiabatic invariant RT and are significant for RT≤ 1 cm K. Special attention was paid to evidence sudden changes in the spectrum intensities, forbidden bands of frequency, as well as major modifications of the total energy for RT≤ 1 cm K. Similar effects were present in case of a cubic cavity too. (authors)
Cr/alpha-Cr2O3 monodispersed spherical core-shell particles based solar absorbers
CSIR Research Space (South Africa)
Khamlich, S
2011-07-01
Full Text Available as reported. The coated Cr/alpha-Cr2O3 spherical particles on rough copper substrates by a simple self-assembly-like method were characterized by scanning electron microscopy, energy dispersive spectrometry, Raman spectroscopy, and diffuse reflectance UV...
Critical experiments on single-unit spherical plutonium geometries reflected and moderated by oil
International Nuclear Information System (INIS)
Rothe, R.E.
1997-05-01
Experimental critical configurations are reported for several dozen spherical and hemispherical single-unit assemblies of plutonium metal. Most were solid but many were hollow-centered, thick, shell-like geometries. All were constructed of nested plutonium (mostly 2139 Pu) metal hemispherical shells. Three kinds of critical configurations are reported. Two required interpolation and/or extrapolation of data to obtain the critical mass because reflector conditions were essentially infinite. The first finds the plutonium essentially fully reflected by a hydrogen-rich oil; the second is essentially unreflected. The third kind reports the critical oil reflector height above a large plutonium metal assembly of accurately known mass (no interpolation required) when that mass was too great to permit full oil reflection. Some configurations had thicknesses of mild steel just outside the plutonium metal, separating it from the oil. These experiments were performed at the Rocky Flats Critical Mass Laboratory in the late 1960s. They have not been published in a form suitable for benchmark-quality comparisons against state-of-the-art computational techniques until this paper. The age of the data and other factors lead to some difficulty in reconstructing aspects of the program and may, in turn, decrease confidence in certain details. Whenever this is true, the point is acknowledged. The plutonium metal was alpha-phase 239 Pu containing 5.9 wt-% 240 Pu. All assemblies were formed by nesting 1.667-mm-thick (nominal) bare plutonium metal hemispherical shells, also called hemishells, until the desired configuration was achieved. Very small tolerance gaps machined into radial dimensions reduced the effective density a small amount in all cases. Steel components were also nested hemispherical shells; but these were nominally 3.333-mm thick. Oil was used as the reflector because of its chemical compatibility with plutonium metal
Interactions between charged spherical macroions
International Nuclear Information System (INIS)
Stevens, M.J.; Falk, M.L.; Robbins, M.O.
1996-01-01
Monte Carlo (MC) simulations were used to study the screened interactions between charged spherical macroions surrounded by discrete counterions, and to test previous theories of screening. The simulations were performed in the primitive cell of the bcc lattice, and in the spherical Wigner endash Seitz cell that is commonly used in approximate calculations. We found that the Wigner endash Seitz approximation is valid even at high volume fractions φ and large macroion charges Z, because the macroion charge becomes strongly screened. Pressures calculated from Poisson endash Boltzmann theory and local density functional theory deviate from MC values as φ and Z increase, but continue to provide upper and lower bounds for the MC results. While Debye endash Hueckel (DH) theory fails badly when the bare charge is used, MC pressures can be fit with an effective DH charge, Z DH , that is nearly independent of volume fraction. As Z diverges, Z DH saturates at zψ max R m /λ, where z is the counterion charge, R m is the macroion radius, λ is the Bjerrum length, and ψ max is a constant of order 10. copyright 1996 American Institute of Physics
National Spherical Torus Experiment (NSTX)
International Nuclear Information System (INIS)
Masayuki Ono
2000-01-01
The main aim of National Spherical Torus Experiment (NSTX) is to establish the fusion physics principles of the innovative spherical torus (ST) concept. Physics outcome of the NSTX research program is relevant to near-term applications such as the Volume Neutron Source (VNS) and burning plasmas, and future applications such as the pilot and power plants. The NSTX device began plasma operations in February 1999 and the plasma current was successfully ramped up to the design value of 1 million amperes (MA) on December 14, 1999. The CHI (Coaxial Helicity Injection) and HHFW (High Harmonic Fast Wave) experiments have also started. Stable CHI discharges of up to 133 kA and 130-msec duration have been produced using 20 kA of injected current. Using eight antennas connected to two transmitters, up to 2 MW of HHFW power was successfully coupled to the plasma. The Neutral-beam Injection (NBI) heating system and associated NBI-based diagnostics such as the Charge-exchange Recombination Spectrometer (CHERS) will be operational in October 2000
Casimir effect in spherical shells
International Nuclear Information System (INIS)
Ruggiero, J.R.
1985-01-01
The analytic regularization method is applied to study the Casimir effect for spherical cavities. Although many works have been presented in the past few years, problems related to the elimination of the regulator parameter still remain. A way to calculate the zero point energy of a perfectly conducting spherical shell which is a miscellaneous of those presented early is here proposed, How a cancelation of divergent terms occurs and how a finite parte is obtained after the elimination of the regulator parameter is shown. As a by-product the zero point energy of the interior vibration modes is obtained and this has some relevance to the quarks bag model. This relev ance is also discussed. The calculation of the energy fom the density view is also discussed. Some works in this field are criticized. The logarithmic divergent terms in the zero point energy are studied when the interior and exterior of the sphere are considered as a medium not dispersive and characterized by a dielectric constants ε 1 and ε 2 and peermeability constants μ 1 and μ 2 respectivelly. The logarithmic divergent terms are not present in the case of ε i μ i =K, with K some constant and i=1,2. (author) [pt
Structural Polymorphism in a Self-Assembled Tri-Aromatic Peptide System.
Brown, Noam; Lei, Jiangtao; Zhan, Chendi; Shimon, Linda J W; Adler-Abramovich, Lihi; Wei, Guanghong; Gazit, Ehud
2018-04-24
Self-assembly is a process of key importance in natural systems and in nanotechnology. Peptides are attractive building blocks due to their relative facile synthesis, biocompatibility, and other unique properties. Diphenylalanine (FF) and its derivatives are known to form nanostructures of various architectures and interesting and varied characteristics. The larger triphenylalanine peptide (FFF) was found to self-assemble as efficiently as FF, forming related but distinct architectures of plate-like and spherical nanostructures. Here, to understand the effect of triaromatic systems on the self-assembly process, we examined carboxybenzyl-protected diphenylalanine (z-FF) as a minimal model for such an arrangement. We explored different self-assembly conditions by changing solvent compositions and peptide concentrations, generating a phase diagram for the assemblies. We discovered that z-FF can form a variety of structures, including nanowires, fibers, nanospheres, and nanotoroids, the latter were previously observed only in considerably larger or co-assembly systems. Secondary structure analysis revealed that all assemblies possessed a β-sheet conformation. Additionally, in solvent combinations with high water ratios, z-FF formed rigid and self-healing hydrogels. X-ray crystallography revealed a "wishbone" structure, in which z-FF dimers are linked by hydrogen bonds mediated by methanol molecules, with a 2-fold screw symmetry along the c-axis. All-atom molecular dynamics (MD) simulations revealed conformations similar to the crystal structure. Coarse-grained MD simulated the assembly of the peptide into either fibers or spheres in different solvent systems, consistent with the experimental results. This work thus expands the building block library for the fabrication of nanostructures by peptide self-assembly.
Enhancement of octupole strength in near spherical nuclei
Energy Technology Data Exchange (ETDEWEB)
Robledo, L.M. [Universidad Autonoma de Madrid, Dep. Fisica Teorica, Facultad de Ciencias, Madrid (Spain)
2016-09-15
The validity of the rotational formula used to compute E1 and E3 transition strengths in even-even nuclei is analyzed within the Generator Coordinate Method framework based on mean field wave functions. It turns out that those nuclei with spherical or near spherical shapes the E1 and E3 strengths computed with this formula are strongly underestimated and a sound evaluation of them requires angular-momentum projected wave functions. Results for several isotopic chains with proton number equal to or near magic numbers are analyzed and compared with experimental data. The use of angular-momentum projected wave functions greatly improves the agreement with the scarce experimental data. (orig.)
Fabrication and electromechanical examination of a spherical dielectric elastomer actuator
International Nuclear Information System (INIS)
Ahmadi, S; Gooyers, M; Soleimani, M; Menon, C
2013-01-01
In this paper, a procedure for fabricating and testing a seamless spherical dielectric elastomer actuator (DEA) is presented. In previously developed spherical prototypes, the DEA material is pre-strained by a rigid frame to improve the actuator’s output force; however, it is possible to pre-strain a spherical DEA by inflating the sample with a liquid or gas as long as the sample contains the pressure. In this work, a very compliant silicone-based material was used to fabricate a nearly spherical balloon-shaped prototype. The DEA sample was inflated by air and various electrical-actuation regimes were considered. The performance of the DEA sample was studied using an analytical and a finite element-based model. An Ogden hyperelastic model was used in formulation of the analytical model to include nonlinear behavior of the silicone material. Full statistical analysis of the experimental and numerical results was carried out using the root-mean-square (RMS) error and the normalized RMS error. The analytical and FEM results were in good agreement with the experimental data. According to modeling results, it was found that the DEA’s actuation force can be mainly improved by increasing the voltage, reducing the thickness, lowering the stiffness, and/or increasing the initial pressure. As an example, a three-fold increase of the actuation force was found when the thickness was reduced to half of its initial value. This improvement of the efficiency suggests that the spherical DEA is suitable for use in several applications if an appropriate design with optimal governing parameters is developed. (paper)
Buckling strength of spherical shells under combined loads
International Nuclear Information System (INIS)
Nagashima, H.; Kokubo, K.; Takayanagi, M.; Hayasaka, Y.; Kume, T.; Nagata, T.
1995-01-01
to the nominal radius of the spherical shell, and a theoretical bucking wavelength (64 mm) in external-pressure buckling. Measured buckling loads are shown to be smaller than those of nonlinear FEM analyses for imperfect shells. It is clarified that these initial imperfections are too small to explain non-linear analysis results. Furthermore, experimental investigation into the effects of cutouts on buckling strengths using spherical shells with circular cutouts under compressive loads prove that decreases in buckling strength due to cutouts are small, the effect of cutouts being smaller for spherical shells than for cylindrical ones. Nonlinear FEM analyses make more clear decreases in buckling strength due to the effect of cut-outs. (author)
The ETE spherical Tokamak project. IAEA report
Energy Technology Data Exchange (ETDEWEB)
Ludwig, Gerson Otto; Del Bosco, E.; Berni, L.A.; Ferreira, J.G.; Oliveira, R.M.; Andrade, M.C.R.; Shibata, C.S.; Barroso, J.J.; Castro, P.J.; Patire Junior, H. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Plasma]. E-mail: ludwig@plasma.inpe.br
2002-07-01
This paper describes the general characteristics of spherical tokamaks, or spherical tori, with a brief overview of work in this area already performed or in progress at several institutions worldwide. The paper presents also the historical development of the ETE (Spherical Tokamak Experiment) project, its research program, technical characteristics and operating conditions as of October, 2002 at the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)
Spherical sila- and germa-homoaromaticity.
Chen, Zhongfang; Hirsch, Andreas; Nagase, Shigeru; Thiel, Walter; Schleyer, Paul von Ragué
2003-12-17
Guided by the 2(N + 1)2 electron-counting rule for spherical aromatic molecules, we have designed various spherical sila- and germa-homoaromatic systems rich in group 14 elements. Their aromaticity is revealed by density-functional computations of their structures and the nucleus-independent chemical shifts (NICS). Besides the formerly used endohedral inclusion strategy, spherical homoaromaticity is another way to stabilize silicon and germanium clusters.
Kasagi, Nobuhide
2000-01-01
The Nusselt Reynolds Prize has been established by the Assembly of World Conferences to commemorate outstanding contributions by Wilhelm Nusselt and Osborne Reynolds as experimentalists, researchers, educators, and authors. As many as three prizes may be bestowed at every World Conference, one in each of the areas of heat transfer, fluid mechanics, thermodynamics, or any combination of these.
Characterization of Rubbers from Spherical Punch - Plate Indentation Tests
Directory of Open Access Journals (Sweden)
Florina Carmen Ciornei
2016-12-01
Full Text Available Rubber plates with different compositions and hardness were tested by continuous indentation, using a spherical punch and hysteretic phenomenon was evidenced. The experimental data interpolation with polynomial functions is accurate and permits estimation of the lost work during loading cycles. The interpolation by power law functions is more convenient by using less parameters and having a form accepted in literature. From the rubbers tested, two were considered to present good damping properties.
The use of rotating electric arc for spherical particle production
International Nuclear Information System (INIS)
Bica, I.
2000-01-01
This work presents and experimental device designed to obtain spherical particles by mans of a rotating electric arc. A rotation frequency of the electric arc of 750 s''-1, a voltage of 50 V(dc) and a current of 100 A was used. The mass flow rate was 3 g.min''-1. Under these conditions particles of 15 to 20 μm in diameter were obtained. (Author) 8 refs
Spherical collapse in chameleon models
International Nuclear Information System (INIS)
Brax, Ph.; Rosenfeld, R.; Steer, D.A.
2010-01-01
We study the gravitational collapse of an overdensity of nonrelativistic matter under the action of gravity and a chameleon scalar field. We show that the spherical collapse model is modified by the presence of a chameleon field. In particular, we find that even though the chameleon effects can be potentially large at small scales, for a large enough initial size of the inhomogeneity the collapsing region possesses a thin shell that shields the modification of gravity induced by the chameleon field, recovering the standard gravity results. We analyse the behaviour of a collapsing shell in a cosmological setting in the presence of a thin shell and find that, in contrast to the usual case, the critical density for collapse in principle depends on the initial comoving size of the inhomogeneity
Spherical collapse in chameleon models
Energy Technology Data Exchange (ETDEWEB)
Brax, Ph. [Institut de Physique Théorique, CEA, IPhT, CNRS, URA 2306, F-91191Gif/Yvette Cedex (France); Rosenfeld, R. [Instituto de Física Teórica, Universidade Estadual Paulista, Rua Dr. Bento T. Ferraz, 271, 01140-070, São Paulo (Brazil); Steer, D.A., E-mail: brax@spht.saclay.cea.fr, E-mail: rosenfel@ift.unesp.br, E-mail: daniele.steer@apc.univ-paris7.fr [APC, UMR 7164, CNRS, Université Paris 7, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13 (France)
2010-08-01
We study the gravitational collapse of an overdensity of nonrelativistic matter under the action of gravity and a chameleon scalar field. We show that the spherical collapse model is modified by the presence of a chameleon field. In particular, we find that even though the chameleon effects can be potentially large at small scales, for a large enough initial size of the inhomogeneity the collapsing region possesses a thin shell that shields the modification of gravity induced by the chameleon field, recovering the standard gravity results. We analyse the behaviour of a collapsing shell in a cosmological setting in the presence of a thin shell and find that, in contrast to the usual case, the critical density for collapse in principle depends on the initial comoving size of the inhomogeneity.
Spherical Collapse in Chameleon Models
Brax, Ph; Steer, D A
2010-01-01
We study the gravitational collapse of an overdensity of nonrelativistic matter under the action of gravity and a chameleon scalar field. We show that the spherical collapse model is modified by the presence of a chameleon field. In particular, we find that even though the chameleon effects can be potentially large at small scales, for a large enough initial size of the inhomogeneity the collapsing region possesses a thin shell that shields the modification of gravity induced by the chameleon field, recovering the standard gravity results. We analyse the behaviour of a collapsing shell in a cosmological setting in the presence of a thin shell and find that, in contrast to the usual case, the critical density for collapse depends on the initial comoving size of the inhomogeneity.
Relativistic fluids in spherically symmetric space
International Nuclear Information System (INIS)
Dipankar, R.
1977-12-01
Some of McVittie and Wiltshire's (1977) solutions of Walker's (1935) isotropy conditions for relativistic perfect fluid spheres are generalized. Solutions are spherically symmetric and conformally flat
Young, Ken (Inventor); Hindle, Timothy (Inventor); Barber, Tim Daniel (Inventor)
2016-01-01
Mounting systems for structural members, fastening assemblies thereof, and vibration isolation systems including the same are provided. Mounting systems comprise a pair of mounting brackets, each clamped against a fastening assembly forming a mounting assembly. Fastening assemblies comprise a spherical rod end comprising a spherical member having a through opening and an integrally threaded shaft, first and second seating members on opposite sides of the spherical member and each having a through opening that is substantially coaxial with the spherical member through opening, and a partially threaded fastener that threadably engages each mounting bracket forming the mounting assembly. Structural members have axial end portions, each releasably coupled to a mounting bracket by the integrally threaded shaft. Axial end portions are threaded in opposite directions for permitting structural member rotation to adjust a length thereof to a substantially zero strain position. Structural members may be vibration isolator struts in vibration isolation systems.
Dellacorte, Christopher; Jefferson, Michael
2015-01-01
Under NASA Space Act Agreement (SAA3-1288), NASA Glenn Research Center and the Kamatics subsidiary of the Kaman Corporation conducted the experimental evaluation of spherical sliding bearings made with 60NiTi inner races. The goal of the project was to assess the feasibility of manufacturing lightweight, corrosion resistant bearings utilizing 60NiTi for aerospace and industrial applications. NASA produced the bearings in collaboration with Abbott Ball Corporation and Kamatics fabricated bearing assemblies utilizing their standard reinforced polymer liner material. The assembled bearings were tested in oscillatory motion at a load of 4.54 kN (10,000 lb), according to the requirements of the plain bearing specification SAE AS81820. Several test bearings were exposed to hydraulic fluid or aircraft deicing fluid prior to and during testing. The results show that the 60NiTi bearings exhibit tribological performance comparable to conventional stainless steel (440C) bearings. Further, exposure of 60NiTi bearings to the contaminant fluids had no apparent performance effect. It is concluded that 60NiTi is a feasible bearing material for aerospace and industrial spherical bearing applications.
Tritium breeding experiments in a fusion blanket assembly using a low-intensity neutron generator
International Nuclear Information System (INIS)
Dalton, A.W.; Woodley, H.J.; McGregor, B.J.
1987-01-01
Experiments have been carried out to determine the accuracy with which tritium production rates (TPRs) can be measured in a fusion blanket assembly of non-spherical geometry by a non-central low intensity D-T neutron source (2x10 10 neutrons per second). The tritium production was determined for samples of lithium carbonate containing high enrichments of 6 Li(96%) and 7 Li(99.9%). The measured data were used to check the accuracy with which the TPRs could be numerically predicted using current nuclear data and calculational methods. The numerical predictions from tritium production from the 7 Li samples agreed within the experimental errors of the measurements, but 6 Li measurements which differ by more than 20 per cent from the predicted values were observed in the lower half of the assembly
A study on heat transfer characteristics of spherical and fibrous alumina nanofluids
International Nuclear Information System (INIS)
Kim, Chang Kyu; Lee, Gyoung-Ja; Rhee, Chang Kyu
2012-01-01
Highlights: ► Spherical and fibrous alumina nanoparticles were prepared by pulsed wire evaporation and hydrolysis methods. ► Fibrous alumina nanofluid exhibited higher thermal conductivity enhancement than spherical one due to entangled structure of nanofibers with high aspect-ratio. ► Decreasing rate of viscosity with temperature for fibrous alumina nanofluid was much larger than that for spherical one. - Abstract: Ethylene glycol based nanofluids containing spherical/fibrous alumina nanoparticles were synthesized by pulsed wire evaporation and hydrolysis methods. The crystallographic and morphological properties of the prepared nanoparticles were analyzed by X-ray diffraction, nitrogen gas adsorption and transmission electron microscopy. The average diameter of spherical alumina nanoparticles was about 80 nm and the alumina nanofibers exhibited a high aspect ratio (length/width). The viscosity and thermal conductivity of the spherical/fibrous alumina nanofluids were experimentally measured in the temperature range from 25 to 80 °C. For the fibrous alumina nanofluid, the increase of temperature raised thermal conductivity but lowered viscosity. On the other hand, for the spherical alumina nanofluid, both thermal conductivity and viscosity were decreased with increasing temperature. In particular, the fibrous alumina nanofluid exhibited a higher enhancement of thermal conductivity than the spherical one due to the well-connected structure between entangled nanofibers with high aspect ratio.
International Nuclear Information System (INIS)
Beaud, F.
1997-01-01
A model predicting the fluid-elastic forces in a bundle of circular cylinders subjected to axial flow is presented in this paper. Whereas previously published models were limited to circular flow channel, the present one allows to take a rectangular flow external boundary into account. For that purpose, an original approach is derived from the standard method of images. This model will eventually be used to predict the fluid-structure coupling between the flow of primary coolant and a fuel assemblies in PWR nuclear reactors. It is indeed of major importance since the flow is shown to induce quite high damping and could therefore mitigate the incidence of an external load like a seismic excitation on the dynamics of the assemblies. The proposed model is validated on two cases from the literature but still needs further comparisons with the experiments being currently carried out on the EDF set-up. The flow has been shown to induce an approximate 12% damping on a PWR fuel assembly, at nominal reactor conditions. The possible grid effect on the fluid-structure coupling has been neglected so far but will soon be investigated at EDF. (author)
Stability of the spherical form of nuclei
International Nuclear Information System (INIS)
Sabry, A.A.
1976-08-01
An extension of the mass formula for a spherical nucleus in the drop model to include a largely deformed nucleus of different forms is investigated. It is found that although the spherical form is stable under small deformations from equilibrium, there exists for heavier nuclei another more favourable stable form, which can be approximated by two, or three touching prolate ellipsoids of revolution
How Spherical Is a Cube (Gravitationally)?
Sanny, Jeff; Smith, David
2015-01-01
An important concept that is presented in the discussion of Newton's law of universal gravitation is that the gravitational effect external to a spherically symmetric mass distribution is the same as if all of the mass of the distribution were concentrated at the center. By integrating over ring elements of a spherical shell, we show that the…
Spherical Tensor Calculus for Local Adaptive Filtering
Reisert, Marco; Burkhardt, Hans
In 3D image processing tensors play an important role. While rank-1 and rank-2 tensors are well understood and commonly used, higher rank tensors are rare. This is probably due to their cumbersome rotation behavior which prevents a computationally efficient use. In this chapter we want to introduce the notion of a spherical tensor which is based on the irreducible representations of the 3D rotation group. In fact, any ordinary cartesian tensor can be decomposed into a sum of spherical tensors, while each spherical tensor has a quite simple rotation behavior. We introduce so called tensorial harmonics that provide an orthogonal basis for spherical tensor fields of any rank. It is just a generalization of the well known spherical harmonics. Additionally we propose a spherical derivative which connects spherical tensor fields of different degree by differentiation. Based on the proposed theory we present two applications. We propose an efficient algorithm for dense tensor voting in 3D, which makes use of tensorial harmonics decomposition of the tensor-valued voting field. In this way it is possible to perform tensor voting by linear-combinations of convolutions in an efficient way. Secondly, we propose an anisotropic smoothing filter that uses a local shape and orientation adaptive filter kernel which can be computed efficiently by the use spherical derivatives.
CFD study on NACA 4415 airfoil implementing spherical and sinusoidal Tubercle Leading Edge.
Aftab, S M A; Ahmad, K A
2017-01-01
The Humpback whale tubercles have been studied for more than a decade. Tubercle Leading Edge (TLE) effectively reduces the separation bubble size and helps in delaying stall. They are very effective in case of low Reynolds number flows. The current Computational Fluid Dynamics (CFD) study is on NACA 4415 airfoil, at a Reynolds number 120,000. Two TLE shapes are tested on NACA 4415 airfoil. The tubercle designs implemented on the airfoil are sinusoidal and spherical. A parametric study is also carried out considering three amplitudes (0.025c, 0.05c and 0.075c), the wavelength (0.25c) is fixed. Structured mesh is utilized to generate grid and Transition SST turbulence model is used to capture the flow physics. Results clearly show spherical tubercles outperform sinusoidal tubercles. Furthermore experimental study considering spherical TLE is carried out at Reynolds number 200,000. The experimental results show that spherical TLE improve performance compared to clean airfoil.
Electrical properties of spherical syncytia.
Eisenberg, R S; Barcilon, V; Mathias, R T
1979-01-01
Syncytial tissues consist of many cells whose intracellular spaces are electrically coupled one to another. Such tissues typically include narrow, tortuous extracellular space and often have specialized membranes at their outer surface. We derive differential equations to describe the potentials induced when a sinusoidal or steady current is applied to the intracellular space with a microelectrode. We derive solutions for spherical preparations with isotropic properties or with a particular anisotropy in effective extracellular and intracellular resistivities. Solutions are presented in an approximate form with a simple physical interpretation. The leading term in the intracellular potential describes an "isopotential" cell in which there is no spatial variation of intracellular potential. The leading term in the extracellular potential, and thus the potential across the inner membranes, varies with radial position, even at zero frequency. The next term of the potentials describes the direct effects of the point source of current and, for the parameters given here, acts as a series resistance producing a large local potential drop essentially independent of frequency. A lumped equivalent circuit describes the "low frequency" behavior of the syncytium, and a distributed circuit gives a reasonably accurate general description. Graphs of the spatial variation and frequency dependence of intracellular, extracellular, and transmembrane potential are given, the response to sinusoidal currents is used to calculate numerically the response to a step function of current.
Intrinsic cylindrical and spherical waves
International Nuclear Information System (INIS)
Ludlow, I K
2008-01-01
Intrinsic waveforms associated with cylindrical and spherical Bessel functions are obtained by eliminating the factors responsible for the inverse radius and inverse square radius laws of wave power per unit area of wavefront. The resulting expressions are Riccati-Bessel functions for both cases and these can be written in terms of amplitude and phase functions of order v and wave variable z. When z is real, it is shown that a spatial phase angle of the intrinsic wave can be defined and this, together with its amplitude function, is systematically investigated for a range of fixed orders and varying z. The derivatives of Riccati-Bessel functions are also examined. All the component functions exhibit different behaviour in the near field depending on the order being less than, equal to or greater than 1/2. Plots of the phase angle can be used to display the locations of the zeros of the general Riccati-Bessel functions and lead to new relations concerning the ordering of the real zeros of Bessel functions and the occurrence of multiple zeros when the argument of the Bessel function is fixed
Alfven Eigenmodes in spherical tokamaks
International Nuclear Information System (INIS)
Gryaznevich, Mikhail P.; Sharapov, Sergei E.; Berk, Herbert L.; Pinches, Simon D.
2005-01-01
Electromagnetic instabilities are often excited by fast super-Alfvenic ions produced by neutral beam injection (NBI) in plasmas of the spherical tokamaks START and MAST (toroidal magnetic confinement devices in which the minor a and major R 0 radii of the torus are comparable, R 0 /a≅1.2/1.8). These instabilities are seen as discrete weakly-damped toroidal and elliptical Alfven Eigenmodes (TAEs and EAEs) with frequencies tracing in time the Alfven scaling with the equilibrium magnetic field and plasma density, or as energetic particle modes (EPMs) whose frequencies don't start from TAE-frequency and sweep down in time faster than the equilibrium parameters change. In some discharges the beam drives Aflvenic-type modes that start from the TAE frequency and sweep in both up- and down- directions. Such electromagnetic perturbations are interpreted as 'hole-clump' long-living nonlinear fluctuations of the fast ion distribution function predicted by Berk-Breizman-Petviashvili [Phys. Lett. A238 (1998) 408]. It is found on both START and MAST that the Alfven instabilities weaken in their mode amplitude and in the number of unstable modes as the pressure of the thermal plasma increases, in agreement with increased thermal ion Landau damping and the pressure effect on core-localised TAEs. (author)
Spherically symmetric charged compact stars
Energy Technology Data Exchange (ETDEWEB)
Maurya, S.K. [University of Nizwa, Department of Mathematical and Physical Sciences, College of Arts and Science, Nizwa (Oman); Gupta, Y.K. [Jaypee Institute of Information Technology University, Department of Mathematics, Noida, Uttar Pradesh (India); Ray, Saibal [Government College of Engineering and Ceramic Technology, Department of Physics, Kolkata, West Bengal (India); Chowdhury, Sourav Roy [Seth Anandaram Jaipuria College, Department of Physics, Kolkata, West Bengal (India)
2015-08-15
In this article we consider the static spherically symmetric metric of embedding class 1. When solving the Einstein-Maxwell field equations we take into account the presence of ordinary baryonic matter together with the electric charge. Specific new charged stellar models are obtained where the solutions are entirely dependent on the electromagnetic field, such that the physical parameters, like density, pressure etc. do vanish for the vanishing charge. We systematically analyze altogether the three sets of Solutions I, II, and III of the stellar models for a suitable functional relation of ν(r). However, it is observed that only the Solution I provides a physically valid and well-behaved situation, whereas the Solutions II and III are not well behaved and hence not included in the study. Thereafter it is exclusively shown that the Solution I can pass through several standard physical tests performed by us. To validate the solution set presented here a comparison has also been made with that of the compact stars, like RX J 1856 - 37, Her X - 1, PSR 1937+21, PSRJ 1614-2230, and PSRJ 0348+0432, and we have shown the feasibility of the models. (orig.)
Beig, Robert; Siddiqui, Azad A.
2007-11-01
It is known that spherically symmetric static spacetimes admit a foliation by flat hypersurfaces. Such foliations have explicitly been constructed for some spacetimes, using different approaches, but none of them have proved or even discussed the uniqueness of these foliations. The issue of uniqueness becomes more important due to suitability of flat foliations for studying black hole physics. Here, flat spherically symmetric spacelike hypersurfaces are obtained by a direct method. It is found that spherically symmetric static spacetimes admit flat spherically symmetric hypersurfaces, and that these hypersurfaces are unique up to translation under the timelike Killing vector. This result guarantees the uniqueness of flat spherically symmetric foliations for such spacetimes.
Transitions between compound states of spherical nuclei
International Nuclear Information System (INIS)
Kadmenskii, S.G.; Markushev, V.P.; Furman, V.I.
1980-01-01
Wigner's statistical matrices are used to study the average reduced g widths and their dispersion for g transitions from a compound state c to another state f, with a lower excitation energy but of arbitrary complexity, for spherical nuclei. It is found that the Porter--Thomas distribution holds for the g widths for all cases of practical interest. In g transitions between compound states c and c' with E/sub g/< or =2 MeV, the most important transitions are M1 transitions involving the major many-quasiparticle components of state c and E1 transitions involving the minor components of state c. It is shown that the strength functions predicted by the various theories for M1 and E1 transitions between compound states with E/sub g/< or =2 MeV are similar. Preference is assigned to the M1-transition version because of experimental results on (n,ga) reactions with thermal and resonance neutrons
Magnetic nanoparticle assemblies
Trohidou, Kalliopi N
2014-01-01
Magnetic nanoparticles with diameters in the range of a few nanometers are today at the cutting edge of modern technology and innovation because of their use in numerous applications ranging from engineering to biomedicine. A great deal of scientific interest has been focused on the functionalization of magnetic nanoparticle assemblies. The understanding of interparticle interactions is necessary to clarify the physics of these assemblies and their use in the development of high-performance magnetic materials. This book reviews prominent research studies on the static and dynamic magnetic properties of nanoparticle assemblies, gathering together experimental and computational techniques in an effort to reveal their optimized magnetic properties for biomedical use and as ultra-high magnetic recording media.
International Nuclear Information System (INIS)
Abe, Hideaki; Sakai, Takao; Ishida, Tomio; Yokota, Norikatsu.
1992-01-01
The lower ends of a plurality of plate-like shape memory alloys are secured at the periphery of the upper inside of the handling head of a fuel assembly. As the shape memory alloy, a Cu-Zn alloy, a Ti-Pd alloy or a Fe-Ni alloy is used. When high temperature coolants flow out to the handling head, the shape memory alloy deforms by warping to the outer side more greatly toward the upper portion thereof with the temperature increase of the coolants. As the result, the shape of the flow channel of the coolants is changed so as to enlarge at the exit of the upper end of the fuel assembly. Then, the pressure loss of the coolants in the fuel assembly is decreased by the enlargement. Accordingly, the flow rate of the coolants in the fuel assembly is increased to lower the temperature of the coolants. Further, high temperature coolants and low temperature coolants are mixed sufficiently just above the fuel assembly. This can suppress the temperature fluctuation of the mixed coolants in the upper portion of the reactor core, thereby enabling to decrease a fatigue and failures of the structural components in the upper portion of the reactor core. (I.N.)
Energy Technology Data Exchange (ETDEWEB)
Klinger, T., E-mail: thomas.klinger@ipp.mpg.de; Baylard, C.; Beidler, C.D.; Boscary, J.; Bosch, H.S.; Dinklage, A.; Hartmann, D.; Helander, P.; Maßberg, H.; Peacock, A.; Pedersen, T.S.; Rummel, T.; Schauer, F.; Wegener, L.; Wolf, R.
2013-10-15
Graphical abstract: The superconducting stellarator device Wendelstein 7-X, currently under construction, is the key device for the proof of stellarator optimization principles. To establish the optimized stellarator as a serious candidate for a fusion reactor, reactor-relevant plasma parameters must be achieved in fully integrated steady-state scenarios. After more than 10 years of construction time, the completion of the device is now approaching rapidly (mid-2014). We discuss the most important lessons learned during the device assembly, first experiences with coming major work packages, and the physics program of the first two operation phases. The concept of a stellarator fusion power plant is outlined, too. Highlights: • The superconducting stellarator device Wendelstein 7-X is presented. • The optimized stellarator may be a serious candidate for a fusion reactor. • Reactor-relevant plasma parameters must be achieved in integrated steady-state scenarios. • We discuss the most important lessons learned during the device assembly. • We discuss first experiences with coming major work packages. • We discuss the physics program of the first two operation phases. • The concept of a stellarator fusion power plant is outlined. -- Abstract: The superconducting stellarator device Wendelstein 7-X, currently under construction, is the key device for the proof of stellarator optimization principles. To establish the optimized stellarator as a serious candidate for a fusion reactor, reactor-relevant dimensionless plasma parameters must be achieved in fully integrated steady-state scenarios. After more than 10 years of construction time, the completion of the device is now approaching rapidly (mid-2014). We discuss the most important lessons learned during the device assembly and first experiences with coming major work packages. Those are (a) assembly of about 2500 large, water-cooled, 3d-shaped in-vessel component elements; (b) assembly of in total 14
Morphological and electrochemical studies of spherical boron doped diamond electrodes
Energy Technology Data Exchange (ETDEWEB)
Mendes de Barros, R.C. [IQ/USP, Av. Lineu Prestes, 748, Bloco 2 Superior, Cidade Universitaria, Sao Paulo/SP, 05508-900 (Brazil); Ferreira, N.G. [LAS/INPE, Av. dos Astronautas, 1758, Jardim da Granja, Sao Jose dos Campos/SP, 12245-970 (Brazil); Azevedo, A.F. [LAS/INPE, Av. dos Astronautas, 1758, Jardim da Granja, Sao Jose dos Campos/SP, 12245-970 (Brazil); Corat, E.J. [LAS/INPE, Av. dos Astronautas, 1758, Jardim da Granja, Sao Jose dos Campos/SP, 12245-970 (Brazil); Sumodjo, P.T.A. [IQ/USP, Av. Lineu Prestes, 748, Bloco 2 Superior, Cidade Universitaria, Sao Paulo/SP, 05508-900 (Brazil); Serrano, S.H.P. [IQ/USP, Av. Lineu Prestes, 748, Bloco 2 Superior, Cidade Universitaria, Sao Paulo/SP, 05508-900 (Brazil)]. E-mail: shps@iq.usp.br
2006-08-14
Morphological and electrochemical characteristics of boron doped diamond electrode in new geometric shape are presented. The main purpose of this study is a comparison among voltammetric behavior of planar glassy carbon electrode (GCE), planar boron doped diamond electrode (PDDE) and spherical boron doped diamond electrode (SDDE), obtained from similar experimental parameters. SDDE was obtained by the growth of boron doped film on textured molybdenum tip. This electrode does not present microelectrode characteristics. However, its voltammetric peak current, determined at low scan rates, is largest associated to the smallest {delta}E {sub p} values for ferrocyanide system when compared with PDDE or GCE. In addition, the capacitance is about 200 times smaller than that for GCE. These results show that the analytical performance of boron doped diamond electrodes can be implemented just by the change of sensor geometry, from plane to spherical shape.
Laser driven compression and neutron generation with spherical shell targets
International Nuclear Information System (INIS)
Campbell, P.M.; Hammerling, P.; Johnson, R.R.; Kubis, J.J.; Mayer, F.J.
1977-01-01
Laser-driven implosion experiments using DT-gas-filled spherical glass-shell targets are described. Neutron yields to 5 x 10 7 are produced from implosions of small ( -- 55 μm-diameter) targets spherically illuminated with an on-target laser power of 0.4 terawatt. Nuclear reaction product diagnostics, X-ray pinhole photographs, fast-ion spectra and X-ray measurements are used in conjunction with hydrodynamic computer code simulations to investigate the implosion phenomenology as well as the target corona evolution. Simulations using completely classical effects are not able to describe the full range of experimental data. Electron or radiation preheating may be required to explain some implosion measurements. (auth.)
Pair distribution function and structure factor of spherical particles
International Nuclear Information System (INIS)
Howell, Rafael C.; Proffen, Thomas; Conradson, Steven D.
2006-01-01
The availability of neutron spallation-source instruments that provide total scattering powder diffraction has led to an increased application of real-space structure analysis using the pair distribution function. Currently, the analytical treatment of finite size effects within pair distribution refinement procedures is limited. To that end, an envelope function is derived which transforms the pair distribution function of an infinite solid into that of a spherical particle with the same crystal structure. Distributions of particle sizes are then considered, and the associated envelope function is used to predict the particle size distribution of an experimental sample of gold nanoparticles from its pair distribution function alone. Finally, complementing the wealth of existing diffraction analysis, the peak broadening for the structure factor of spherical particles, expressed as a convolution derived from the envelope functions, is calculated exactly for all particle size distributions considered, and peak maxima, offsets, and asymmetries are discussed
Realization of a Service Robot for Cleaning Spherical Surfaces
Directory of Open Access Journals (Sweden)
Houxiang Zhang
2005-03-01
Full Text Available There are more and more buildings with complicated shape emerging all over the world. Their walls require constant cleaning which is difficult to realize. In this paper, based on analyzing the characteristics of the working target, a new kind of auto-climbing robot is proposed, which is used for cleaning the spherical surface of the National GrandTheatre in China. The robots' mechanism and unique aspects are presented in detail. A distributed controller based onCAN bus is designed to meet the requirements of controlling the robot. The control system is divided into 6 parts, fiveCAN bus control nodes and a remote controller, which are designed and established based mainly on the P80C592. Finally, the motion function is described in detail. The experimental results confirm the principle described above andthe robot's ability to work on the spherical surface.
International Nuclear Information System (INIS)
Nakatsuka, Masafumi; Matsuzuka, Ryuji.
1976-01-01
Object: To provide a fuel assembly which can decrease pressure loss of coolant to uniform temperature. Structure: A sectional area of a flow passage in the vicinity of an inner peripheral surface of a wrapper tube is limited over the entire length to prevent the temperature of a fuel element in the outermost peripheral portion from being excessively decreased to thereby flatten temperature distribution. To this end, a plurality of pincture-frame-like sheet metals constituting a spacer for supporting a fuel assembly, which has a plurality of fuel elements planted lengthwise and in given spaced relation within the wrapper tube, is disposed in longitudinal grooves and in stacked fashion to form a substantially honeycomb-like space in cross section. The fuel elements are inserted and supported in the space to form a fuel assembly. (Kamimura, M.)
International Nuclear Information System (INIS)
Nagano, Mamoru; Yoshioka, Ritsuo
1983-01-01
Purpose: To effectively utilize nuclear fuels by increasing the reactivity of a fuel assembly and reduce the concentration at the central region thereof upon completion of the burning. Constitution: A fuel assembly is bisected into a central region and a peripheral region by disposing an inner channel box within a channel box. The flow rate of coolants passing through the central region is made greater than that in the peripheral region. The concentration of uranium 235 of the fuel rods in the central region is made higher. In such a structure, since the moderating effect in the central region is improved, the reactivity of the fuel assembly is increased and the uranium concentration in the central region upon completion of the burning can be reduced, fuel economy and effective utilization of uranium can be attained. (Kamimura, M.)
Self-assembly of coiled coil peptides into nanoparticles vs 2-d plates: effects of assembly pathway
Kim, Kyunghee; Pochan, Darrin
Molecular solution assembly, or self-assembly, is a process by which ordered nanostructures or patterns are formed by non-covalent interactions during assembly. Biomimicry, the use of bioinspired molecules or biologically relevant materials, is an important area of self-assembly research with peptides serving a critical role as molecular tools. The morphology of peptide assemblies can be controlled by adjusting solution conditions such as the concentration of peptides, the temperature, and pH. Herein, spherical nanostructures, which have potential for creating an encapsulation system, are formed by self-assembly when coiled coil peptides are combined in solution. These peptides are homotrimeric and heterodimeric coiled-coil bundles and the homotrimer is connected with each of heterodimer through their external surfaces via disulfide bonds. The resultant covalent constructs could co-assemble into complementary trimeric hubs, respectively. The two peptide constructs are directly mixed and assembled in solution in order to produce either spherical particles or 2-d plates depending on the solution conditions and kinetic pathway of assembly. In particular, structural changes of the self-assembled peptides are explored by control of the thermal history of the assembly solution.
Modeling mantle convection in the spherical annulus
Hernlund, John W.; Tackley, Paul J.
2008-12-01
Most methods for modeling mantle convection in a two-dimensional (2D) circular annular domain suffer from innate shortcomings in their ability to capture several characteristics of the spherical shell geometry of planetary mantles. While methods such as rescaling the inner and outer radius to reduce anomalous effects in a 2D polar cylindrical coordinate system have been introduced and widely implemented, such fixes may have other drawbacks that adversely affect the outcome of some kinds of mantle convection studies. Here we propose a new approach that we term the "spherical annulus," which is a 2D slice that bisects the spherical shell and is quantitatively formulated at the equator of a spherical polar coordinate system after neglecting terms in the governing equations related to variations in latitude. Spherical scaling is retained in this approximation since the Jacobian function remains proportional to the square of the radius. We present example calculations to show that the behavior of convection in the spherical annulus compares favorably against calculations performed in other 2D annular domains when measured relative to those in a fully three-dimensional (3D) spherical shell.
Compression dynamics of quasi-spherical wire arrays with different linear mass profiles
International Nuclear Information System (INIS)
Mitrofanov, K. N.; Aleksandrov, V. V.; Gritsuk, A. N.; Grabovski, E. V.; Frolov, I. N.; Laukhin, Ya. N.; Oleinik, G. M.; Ol’khovskaya, O. G.
2016-01-01
Results of experimental studies of the implosion of quasi-spherical wire (or metalized fiber) arrays are presented. The goal of the experiments was to achieve synchronous three-dimensional compression of the plasma produced in different regions of a quasi-spherical array into its geometrical center. To search for optimal synchronization conditions, quasi-spherical arrays with different initial profiles of the linear mass were used. The following dependences of the linear mass on the poloidal angle were used: m_l(θ) ∝ sin"–"1θ and m_l(θ) ∝ sin"–"2θ. The compression dynamics of such arrays was compared with that of quasi-spherical arrays without linear mass profiling, m_l(θ) = const. To verify the experimental data, the spatiotemporal dynamics of plasma compression in quasi-spherical arrays was studied using various diagnostics. The experiments on three-dimensional implosion of quasi-spherical arrays made it possible to study how the frozen-in magnetic field of the discharge current penetrates into the array. By measuring the magnetic field in the plasma of a quasi-spherical array, information is obtained on the processes of plasma production and formation of plasma flows from the wire/fiber regions with and without an additionally deposited mass. It is found that penetration of the magnetic flux depends on the initial linear mass profile m_l(θ) of the quasi-spherical array. From space-resolved spectral measurements and frame imaging of plasma X-ray emission, information is obtained on the dimensions and shape of the X-ray source formed during the implosion of a quasi-spherical array. The intensity of this source is estimated and compared with that of the Z-pinch formed during the implosion of a cylindrical array.
Averaging in spherically symmetric cosmology
International Nuclear Information System (INIS)
Coley, A. A.; Pelavas, N.
2007-01-01
The averaging problem in cosmology is of fundamental importance. When applied to study cosmological evolution, the theory of macroscopic gravity (MG) can be regarded as a long-distance modification of general relativity. In the MG approach to the averaging problem in cosmology, the Einstein field equations on cosmological scales are modified by appropriate gravitational correlation terms. We study the averaging problem within the class of spherically symmetric cosmological models. That is, we shall take the microscopic equations and effect the averaging procedure to determine the precise form of the correlation tensor in this case. In particular, by working in volume-preserving coordinates, we calculate the form of the correlation tensor under some reasonable assumptions on the form for the inhomogeneous gravitational field and matter distribution. We find that the correlation tensor in a Friedmann-Lemaitre-Robertson-Walker (FLRW) background must be of the form of a spatial curvature. Inhomogeneities and spatial averaging, through this spatial curvature correction term, can have a very significant dynamical effect on the dynamics of the Universe and cosmological observations; in particular, we discuss whether spatial averaging might lead to a more conservative explanation of the observed acceleration of the Universe (without the introduction of exotic dark matter fields). We also find that the correlation tensor for a non-FLRW background can be interpreted as the sum of a spatial curvature and an anisotropic fluid. This may lead to interesting effects of averaging on astrophysical scales. We also discuss the results of averaging an inhomogeneous Lemaitre-Tolman-Bondi solution as well as calculations of linear perturbations (that is, the backreaction) in an FLRW background, which support the main conclusions of the analysis
International Nuclear Information System (INIS)
Buinitskii, B.A.; Kaplar, E.P.; Kondrat'ev, F.V.; Leppik, P.A.; Nafikov, D.Ya.; Pavelko, V.I.; Rychev, A.S.; Tarasov, V.P.; Khlopkin, N.S.
1993-01-01
At the beginning of the seventies, the concept of building small atomic power stations with direct conversion of the thermal energy of a reactor for supplying electricity and heat to consumers located at remote and inaccessible regions was developed on the basis of assessment calculations and technical studies made in the I.V. Kurchatov Institute of Atomic Energy. When new technical solutions were adopted to put this concept into practice, combined trials on a test stand were required. For this purpose, the nuclear thermoelectric test-demonstration assembly open-quotes Gammaclose quotes was built and put into operation in 1981. It is based on the three principles which determine the development of unattended self-regulating nuclear thermoelectric stations: using a water-water reactor with self-regulation of the power as a source of heat; using a cooling system without pumps but with natural circulation of the coolant in the primary and intermediate circuits for removing the hend thermoelectric conversion of heat into electricity. During the ten years of operation of the open-quotes Gammaclose quotes assembly, a research program on the principles of unattended self-regulating nuclear thermoelectric stations was carried out and the results are summarized
Elastic interaction between surface and spherical pore
International Nuclear Information System (INIS)
Ganeev, G.Z.; Kadyrzhanov, K.K.; Kislitsyn, S.B.; Turkebaev, T.Eh.
2000-01-01
The energy of elastic interaction of a gas-filled spherical cavity with a boundary of an elastic isotropic half-space is determined. The elastic field of a system of a spherical cavity - boundary is represented as an expansion in series of potential functions. The factors of expansions are determined by boundary conditions on a free surface of an elastic half-space and on a spherical surface of a cavity with pressure of gas P. Function of a Tresca-Miesesa on a surface of elastic surface is defined additionally with purpose creep condition determination caused by gas pressure in the cavity. (author)
International Nuclear Information System (INIS)
Sandling, M.
1981-01-01
An improved valve assembly, used for controlling the flow of radioactive slurry, is described. Radioactive contamination of the air during removal or replacement of the valve is prevented by sucking air from the atmosphere through a portion of the structure above the valve housing. (U.K.)
International Nuclear Information System (INIS)
Gjertsen, R.K.; Bassler, E.A.; Huckestein, E.A.; Salton, R.B.; Tower, S.N.
1988-01-01
A fuel assembly adapted for use with a pressurized water nuclear reactor having capabilities for fluid moderator spectral shift control is described comprising: parallel arranged elongated nuclear fuel elements; means for providing for axial support of the fuel elements and for arranging the fuel elements in a spaced array; thimbles interspersed among the fuel elements adapted for insertion of a rod control cluster therewithin; means for structurally joining the fuel elements and the guide thimbles; fluid moderator control means for providing a volume of low neutron absorbing fluid within the fuel assembly and for removing a substantially equivalent volume of reactor coolant water therefrom, a first flow manifold at one end of the fuel assembly sealingly connected to a first end of the moderator control tubes whereby the first ends are commonly flow connected; and a second flow manifold, having an inlet passage and an outlet passage therein, sealingly connected to a second end of the moderator control tubes at a second end of the fuel assembly
Design of the ITER Tokamak Assembly Tools
International Nuclear Information System (INIS)
Park, Hyunki; Her, Namil; Kim, Byungchul; Im, Kihak; Jung, Kijung; Lee, Jaehyuk; Im, Kisuk
2006-01-01
ITER (International Thermonuclear Experimental Reactor) Procurement allocation among the seven Parties, EU, JA, CN, IN , KO, RF and US had been decided in Dec. 2005. ITER Tokamak assembly tools is one of the nine components allocated to Korea for the construction of the ITER. Assembly tools except measurement and common tools are supplied to assemble the ITER Tokamak and classified into 9 groups according to components to be assembled. Among the 9 groups of assembly tools, large-sized Sector Sub-assembly Tools and Sector Assembly Tools are used at the first stage of ITER Tokamak construction and need to be designed faster than seven other assembly tools. ITER IT (International Team) proposed Korea to accomplish ITA (ITER Transitional Arrangements) Task on detailed design, manufacturing feasibility and contract specification of specific, large sized tools such as Upending Tool, Lifting Tool, Sector Sub-assembly Tool and Sector Assembly Tool in Oct. 2004. Based on the concept design by ITER IT, Korea carried out ITA Task on detailed design of large-sized and specific Sector Sub-assembly and Sector Assembly Tools until Mar. 2006. The Sector Sub-assembly Tools mainly consist of the Upending, Lifting, Vacuum Vessel Support and Bracing, and Sector Sub-assembly Tool, among which the design of three tools are herein. The Sector Assembly Tools mainly consist of the Toroidal Field (TF) Gravity Support Assembly, Sector In-pit Assembly, TF Coil Assembly, Vacuum Vessel (VV) Welding and Vacuum Vessel Thermal Shield (TS) Assembly Tool, among which the design of Sector In-pit Assembly Tool is described herein
Barth, K; Dudarev, A; Passardi, Giorgio; Pengo, R; Pezzetti, M; Pirrote, O; Ten Kate, H; Baynham, E; Mayri, C
2008-01-01
The large ATLAS superconducting magnets system consists of the Barrel, two End-Caps Toroids and the Central Solenoid. The eight separate coils making the Barrel Toroid (BT) have been individually tested with success in a dedicated surface test facility in 2004 and 2005 and afterwards assembled in the underground cavern of the ATLAS experiment. In order to fulfil all the cryogenic scenarios foreseen for these magnets with a cold mass of 370 tons, two separate helium refrigerators and a complex helium distribution system have been used. This paper describes the results of the first cool-down, steady-state operation at 4.5 K and quench recovery of the BT in its final configuration.
Directory of Open Access Journals (Sweden)
Fang Wu
2017-05-01
Full Text Available Due to their efficient locomotion and natural tolerance to hazardous environments, spherical robots have wide applications in security surveillance, exploration of unknown territory and emergency response. Numerous studies have been conducted on the driving mechanism, motion planning and trajectory tracking methods of spherical robots, yet very limited studies have been conducted regarding the obstacle avoidance capability of spherical robots. Most of the existing spherical robots rely on the “hit and run” technique, which has been argued to be a reasonable strategy because spherical robots have an inherent ability to recover from collisions. Without protruding components, they will not become stuck and can simply roll back after running into bstacles. However, for small scale spherical robots that contain sensitive surveillance sensors and cannot afford to utilize heavy protective shells, the absence of obstacle avoidance solutions would leave the robot at the mercy of potentially dangerous obstacles. In this paper, a compact magnetic field-based obstacle detection and avoidance system has been developed for miniature spherical robots. It utilizes a passive magnetic field so that the system is both compact and power efficient. The proposed system can detect not only the presence, but also the approaching direction of a ferromagnetic obstacle, therefore, an intelligent avoidance behavior can be generated by adapting the trajectory tracking method with the detection information. Design optimization is conducted to enhance the obstacle detection performance and detailed avoidance strategies are devised. Experimental results are also presented for validation purposes.
Monodromy in the quantum spherical pendulum
International Nuclear Information System (INIS)
Guillemin, V.; Uribe, A.
1989-01-01
In this article we show that monodromy in the quantum spherical pendulum can be interpreted as a Maslov effect: i.e. as multi-valuedness of a certain generating function of the quantum energy levels. (orig.)
Transformation of Real Spherical Harmonics under Rotations
Romanowski, Z.; Krukowski, St.; Jalbout, A. F.
2008-08-01
The algorithm rotating the real spherical harmonics is presented. The convenient and ready to use formulae for l = 0, 1, 2, 3 are listed. The rotation in R3 space is determined by the rotation axis and the rotation angle; the Euler angles are not used. The proposed algorithm consists of three steps. (i) Express the real spherical harmonics as the linear combination of canonical polynomials. (ii) Rotate the canonical polynomials. (iii) Express the rotated canonical polynomials as the linear combination of real spherical harmonics. Since the three step procedure can be treated as a superposition of rotations, the searched rotation matrix for real spherical harmonics is a product of three matrices. The explicit formulae of matrix elements are given for l = 0, 1, 2, 3, what corresponds to s, p, d, f atomic orbitals.
Optical properties of spherical gold mesoparticles
DEFF Research Database (Denmark)
Evlyukhin, A. B.; Kuznetsov, A. I.; Novikov, S. M.
2012-01-01
Optical properties of spherical gold particles with diameters of 150-650 nm (mesoparticles) are studied by reflectance spectroscopy. Particles are fabricated by laser-induced transfer of metallic droplets onto metal and dielectric substrates. Contributions of higher multipoles (beyond...
Spiral CT manifestations of spherical pneumonia
International Nuclear Information System (INIS)
Li Xiaohong; Yang Hongwei; Xu Chunmin; Qin Xiu
2008-01-01
Objective: To explore the Spiral CT manifestations and differential diagnosis of spherical pneumonia. Methods: 18 cases of spherical pneumonia and 20 cases of peripheral pulmonary carcinoma were selected, both of them were confirmed by clinic and/or pathology. The SCT findings of both groups were compared retrospectively. Results: Main spiral CT findings of spherical pneumonia were showed as followings: square or triangular lesions adjacent to pleura; with irregular shape, blurry, slightly lobulated margin, sometimes with halo sign. Small inflammatory patches and intensified vascular markings around the lesions were seen. Lesions became smaller or vanished after short-term anti-inflammatory treatment. Conclusion: Spherical pneumonia showed some characteristics on Spiral CT scan, which are helpful in diagnosis and differential diagnosis of this disease. (authors)
FY 2006 Miniature Spherical Retroreflectors Final Report
Energy Technology Data Exchange (ETDEWEB)
Anheier, Norman C.; Bernacki, Bruce E.; Krishnaswami, Kannan
2006-12-28
Research done by the Infrared Photonics team at Pacific Northwest National Laboratory (PNNL) is focused on developing miniature spherical retroreflectors using the unique optical and material properties of chalcogenide glass to reduce both performance limiting spherical aberrations. The optimized optical performance will provide efficient signal retroreflection that enables a broad range of remote detection scenarios for mid-wave infrared (MWIR) and long-wave infrared (LWIR) sensing applications. Miniature spherical retroreflectors can be developed to aid in the detection of signatures of nuclear proliferation or other chemical vapor or radiation signatures. Miniature spherical retroreflectors are not only well suited to traditional LIDAR methods for chemical plume detection and identification, but could enable remote detection of difficult semi-volatile chemical materials or low level radiation sources.
Feasibility study for the Spherical Torus Experiment
International Nuclear Information System (INIS)
Lazarus, E.A.; Attenberger, S.E.; Baylor, L.R.
1985-10-01
The design of the Spherical Torus Experiment (STX) is discussed. The physics of the plasma are given in a magnetohydrodynamic model. The structural aspects and instrumentation of the device are described. 19 refs., 103 figs
3D Printing Electrically Small Spherical Antennas
DEFF Research Database (Denmark)
Kim, Oleksiy S.
2013-01-01
3D printing is applied for rapid prototyping of an electrically small spherical wire antenna. The model is first printed in plastic and subsequently covered with several layers of conductive paint. Measured results are in good agreement with simulations.......3D printing is applied for rapid prototyping of an electrically small spherical wire antenna. The model is first printed in plastic and subsequently covered with several layers of conductive paint. Measured results are in good agreement with simulations....
Method of producing spherical lithium aluminate particles
International Nuclear Information System (INIS)
Yang, L.; Medico, R.R.; Baugh, W.A.
1983-01-01
Spherical particles of lithium aluminate are formed by initially producing aluminium hydroxide spheroids, and immersing the spheroids in a lithium ion-containing solution to infuse lithium ions into the spheroids. The lithium-infused spheroids are rinsed to remove excess lithium ion from the surface, and the rinsed spheroids are soaked for a period of time in a liquid medium, dried and sintered to form lithium aluminate spherical particles. (author)
Spherical cows in dark matter indirect detection
Energy Technology Data Exchange (ETDEWEB)
Bernal, Nicolás [Centro de Investigaciones, Universidad Antonio Nariño, Cra 3 Este # 47A-15, Bogotá (Colombia); Necib, Lina; Slatyer, Tracy R., E-mail: nicolas.bernal@uan.edu.co, E-mail: lnecib@mit.edu, E-mail: tslatyer@mit.edu [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
2016-12-01
Dark matter (DM) halos have long been known to be triaxial, but in studies of possible annihilation and decay signals they are often treated as approximately spherical. In this work, we examine the asymmetry of potential indirect detection signals of DM annihilation and decay, exploiting the large statistics of the hydrodynamic simulation Illustris. We carefully investigate the effects of the baryons on the sphericity of annihilation and decay signals for both the case where the observer is at 8.5 kpc from the center of the halo (exemplified in the case of Milky Way-like halos), and for an observer situated well outside the halo. In the case of Galactic signals, we find that both annihilation and decay signals are expected to be quite symmetric, with axis ratios very different from 1 occurring rarely. In the case of extragalactic signals, while decay signals are still preferentially spherical, the axis ratio for annihilation signals has a much flatter distribution, with elongated profiles appearing frequently. Many of these elongated profiles are due to large subhalos and/or recent mergers. Comparing to gamma-ray emission from the Milky Way and X-ray maps of clusters, we find that the gamma-ray background appears less spherical/more elongated than the expected DM signal from the large majority of halos, and the Galactic gamma ray excess appears very spherical, while the X-ray data would be difficult to distinguish from a DM signal by elongation/sphericity measurements alone.
Visual Detection and Tracking System for a Spherical Amphibious Robot.
Guo, Shuxiang; Pan, Shaowu; Shi, Liwei; Guo, Ping; He, Yanlin; Tang, Kun
2017-04-15
With the goal of supporting close-range observation tasks of a spherical amphibious robot, such as ecological observations and intelligent surveillance, a moving target detection and tracking system was designed and implemented in this study. Given the restrictions presented by the amphibious environment and the small-sized spherical amphibious robot, an industrial camera and vision algorithms using adaptive appearance models were adopted to construct the proposed system. To handle the problem of light scattering and absorption in the underwater environment, the multi-scale retinex with color restoration algorithm was used for image enhancement. Given the environmental disturbances in practical amphibious scenarios, the Gaussian mixture model was used to detect moving targets entering the field of view of the robot. A fast compressive tracker with a Kalman prediction mechanism was used to track the specified target. Considering the limited load space and the unique mechanical structure of the robot, the proposed vision system was fabricated with a low power system-on-chip using an asymmetric and heterogeneous computing architecture. Experimental results confirmed the validity and high efficiency of the proposed system. The design presented in this paper is able to meet future demands of spherical amphibious robots in biological monitoring and multi-robot cooperation.
Dynamics of Shape Fluctuations of Quasi-spherical Vesicles Revisited
DEFF Research Database (Denmark)
Miao, L.; Lomholt, Michael Andersen; Kleis, J.
2002-01-01
In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed from a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations, and a sy......In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed from a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations...... of the phenomenological constants in a canonical continuum description of fluid lipid-bilayer membranes and shown the consequences of this new interpretation in terms of the characteristics of the dynamics of vesicle shape fluctuations. Moreover, we have used the systematic formulation of our theory as a framework...... against which we have discussed the previously existing theories and their discrepancies. Finally, we have made a systematic prediction about the system-dependent characteristics of the relaxation dynamics of shape fluctuations of quasi-spherical vesicles with a view of experimental studies...
Visual Detection and Tracking System for a Spherical Amphibious Robot
Guo, Shuxiang; Pan, Shaowu; Shi, Liwei; Guo, Ping; He, Yanlin; Tang, Kun
2017-01-01
With the goal of supporting close-range observation tasks of a spherical amphibious robot, such as ecological observations and intelligent surveillance, a moving target detection and tracking system was designed and implemented in this study. Given the restrictions presented by the amphibious environment and the small-sized spherical amphibious robot, an industrial camera and vision algorithms using adaptive appearance models were adopted to construct the proposed system. To handle the problem of light scattering and absorption in the underwater environment, the multi-scale retinex with color restoration algorithm was used for image enhancement. Given the environmental disturbances in practical amphibious scenarios, the Gaussian mixture model was used to detect moving targets entering the field of view of the robot. A fast compressive tracker with a Kalman prediction mechanism was used to track the specified target. Considering the limited load space and the unique mechanical structure of the robot, the proposed vision system was fabricated with a low power system-on-chip using an asymmetric and heterogeneous computing architecture. Experimental results confirmed the validity and high efficiency of the proposed system. The design presented in this paper is able to meet future demands of spherical amphibious robots in biological monitoring and multi-robot cooperation. PMID:28420134
Energy Technology Data Exchange (ETDEWEB)
Akkus, Harun [Technical Sciences Vocational School, Amasya University, Amasya (Turkmenistan); Duzcukoglu, Hayrettin; Sahin, Omer Sinan [Mechanical Engineering Department, Selcuk University, Selcuk (Turkmenistan)
2017-01-15
This study utilized experimental and finite element methods to investigate the mechanical behavior of aluminum honeycomb structures under compression. Aluminum honeycomb composite structures were subjected to pressing experiments according to the standard ASTM C365. Resistive forces in response to compression and maximum compressive force values were measured. Structural damage was observed. In the honeycomb structure, the cell width decreased as the compressive force increased. Results obtained with finite element models generated using ANSYS Workbench 15 were validated. Experimental results paralleled the finite element modeling results. The ANSYS results were approximately 85 % reliable.
The Self- and Directed Assembly of Nanowires
Smith, Benjamin David
This thesis explores the self- and directed assembly of nanowires. Specifically, we examine the driving forces behind nanowire self-assembly and the macro-structures that are formed. Particle-dense, oriented nanowire structures show promise in the fields of photonics, energy, sensing, catalysis, and electronics. Arrays of spherical particles have already found uses in electronic inks, sensing arrays, and many other commercial applications; but, it is a challenge to create specific arrays of morphologically and/or compositionally anisotropic particles. The following chapters illuminate the interactions that drive the assembly of anisotropic particles in high density solutions in the absence of applied fields or solution drying. Special emphasis is placed on the structures that are formed. The properties of micro- and nanoparticles and their assembly are introduced in Chapter 1. In particular, the properties of shape and material anisotropic particles are highlighted, while challenges in producing desired arrays are discussed. In this thesis, metallic nanowires of increasing complexity were used to examine the self-assembly behavior of both shape and material anisotropic particles. Nanowires were synthesized through templated electrodeposition. In this process, porous alumina membranes served as a template in which metal salts were reduced to form particles. Upon template dissolution, billions of nominally identical particles were released. We specifically focused on segmented, metallic nanowires 2-13 mum in length and 180 to 350 nm in diameter. Since these particles have strong van der Waals (VDWs) attractions, an electrostatically repulsive coating was necessary to prevent aggregation; we used small molecule, DNA, or amorphous silica coatings. Nanowires and their coatings were characterized by electron microscopy. In order to study self-assembly behavior, particle-dense aqueous suspensions were placed within an assembly chamber defined by a silicone spacer. The
Self-assembling segmented coiled tubing
Raymond, David W.
2016-09-27
Self-assembling segmented coiled tubing is a concept that allows the strength of thick-wall rigid pipe, and the flexibility of thin-wall tubing, to be realized in a single design. The primary use is for a drillstring tubular, but it has potential for other applications requiring transmission of mechanical loads (forces and torques) through an initially coiled tubular. The concept uses a spring-loaded spherical `ball-and-socket` type joint to interconnect two or more short, rigid segments of pipe. Use of an optional snap ring allows the joint to be permanently made, in a `self-assembling` manner.
International Nuclear Information System (INIS)
Yokota, Tokunobu.
1990-01-01
A fuel assembly used in a FBR type nuclear reactor comprises a plurality of fuel rods and a moderator guide member (water rod). A moderator exit opening/closing mechanism is formed at the upper portion of the moderator guide member for opening and closing a moderator exit. In the initial fuel charging operation cycle to the reactor, the moderator exit is closed by the moderator exit opening/closing mechanism. Then, voids are accumulated at the inner upper portion of the moderator guide member to harden spectrum and a great amount of plutonium is generated and accumulated in the fuel assembly. Further, in the fuel re-charging operation cycle, the moderator guide member is used having the moderator exit opened. In this case, voids are discharged from the moderator guide member to decrease the ratio, and the plutonium accumulated in the initial charging operation cycle is burnt. In this way, the fuel economy can be improved. (I.N.)
International Nuclear Information System (INIS)
Echigoya, Hironori; Nomata, Terumitsu.
1983-01-01
Purpose: To render the axial distribution relatively flat. Constitution: First nuclear element comprises a fuel can made of zircalloy i.e., the metal with less neutron absorption, which is filled with a plurality of UO 2 pellets and sealed by using a lower end plug, a plenum spring and an upper end plug by means of welding. Second fuel element is formed by substituting a part of the UO 2 pellets with a water tube which is sealed with water and has a space for allowing the heat expansion. The nuclear fuel assembly is constituted by using the first and second fuel elements together. In such a structure, since water reflects neutrons and decrease their leakage to increase the temperature, reactivity is added at the upper portion of the fuel assembly to thereby flatten the axial power distribution. Accordingly, stable operation is possible only by means of deep control rods while requiring no shallow control rods. (Sekiya, K.)
International Nuclear Information System (INIS)
Kawai, Mitsuo.
1988-01-01
Purpose: To reduce the corrosion rate and suppress the increase of radioactive corrosion products in reactor water of nuclear fuel assemblies for use in BWR type reactors having spacer springs made of nickel based deposition reinforced type alloys. Constitution: Spacer rings made of nickel based deposition reinforced type alloy are incorporated and used as fuel assemblies after applying treatment of dipping and maintaining at high temperature water followed by heating in steams. Since this can remove the nickel leaching into reactor water at the initial stage, Co-58 as the radioactive corrosion products in the reactor water can be reduced, and the operation at in-service inspection or repairement can be facilitated to improve the working efficiency of the nuclear power plant. The dipping time is desirably more than 10 hours and more desirably more than 30 hours. (Horiuchi, T. )
International Nuclear Information System (INIS)
Watanabe, Shoichi; Hirano, Yasushi.
1998-01-01
A one-half or more of entire fuel rods in a fuel assembly comprises MOX fuel rods containing less than 1wt% of burnable poisons, and at least a portion of the burnable poisons comprises gadolinium. Then, surplus reactivity at an initial stage of operation cycle is controlled to eliminate burnable poisons remained unburnt at a final stage, as well as increase thermal reactivity. In addition, the content of fission plutonium is determined to greater than the content of uranium 235, and fuel rods at corner portions are made not to incorporate burnable poisons. Fuel rods not containing burnable poisons are disposed at positions in adjacent with fuel rods facing to a water rod at one or two directions. Local power at radial center of the fuel assembly is increased to flatten the distortion of radial power distribution. (N.H.)
International Nuclear Information System (INIS)
Aoi, Y; Tominaga, T
2013-01-01
Titanium dioxide (TiO 2 ) inverse opals in spherical shape were prepared by liquid phase deposition (LPD) using spherical colloidal crystals as templates. Spherical colloidal crystals were produced by ink-jet drying technique. Aqueous emulsion droplets that contain polystyrene latex particles were ejected into air and dried. Closely packed colloidal crystals with spherical shape were obtained. The obtained spherical colloidal crystals were used as templates for the LPD. The templates were dispersed in the deposition solution of the LPD, i.e. a mixed solution of ammonium hexafluorotitanate and boric acid and reacted for 4 h at 30 °C. After the LPD process, the interstitial spaces of the spherical colloidal crystals were completely filled with titanium oxide. Subsequent heat treatment resulted in removal of templates and spherical titanium dioxide inverse opals. The spherical shape of the template was retained. SEM observations indicated that the periodic ordered voids were surrounded by titanium dioxide. The optical reflectance spectra indicated that the optical properties of the spherical titanium dioxide inverse opals were due to Bragg diffractions from the ordered structure. Filling in the voids of the inverse opals with different solvents caused remarkable changes in the reflectance peak.
Staff Association
2016-01-01
5th April, 2016 – Ordinary General Assembly of the Staff Association! In the first semester of each year, the Staff Association (SA) invites its members to attend and participate in the Ordinary General Assembly (OGA). This year the OGA will be held on Tuesday, April 5th 2016 from 11:00 to 12:00 in BE Auditorium, Meyrin (6-2-024). During the Ordinary General Assembly, the activity and financial reports of the SA are presented and submitted for approval to the members. This is the occasion to get a global view on the activities of the SA, its financial management, and an opportunity to express one’s opinion, including taking part in the votes. Other points are listed on the agenda, as proposed by the Staff Council. Who can vote? Only “ordinary” members (MPE) of the SA can vote. Associated members (MPA) of the SA and/or affiliated pensioners have a right to vote on those topics that are of direct interest to them. Who can give his/her opinion? The Ordinary General Asse...
International Nuclear Information System (INIS)
Ueda, Sei; Ando, Ryohei; Mitsutake, Toru.
1995-01-01
The present invention concerns a fuel assembly suitable to a BWR-type reactor and improved especially with the nuclear characteristic, heat performance, hydraulic performance, dismantling or assembling performance and economical property. A part of poison rods are formed as a large-diameter/multi-region poison rods having a larger diameter than a fuel rod. A large number of fuel rods are disposed surrounding a large diameter water rod and a group of the large-diameter/multi-region poison rods in adjacent with the water rod. The large-diameter water rod has a burnable poison at the tube wall portion. At least a portion of the large-diameter poison rods has a coolant circulation portion allowing coolants to circulate therethrough. Since the large-diameter poison rods are disposed at a position of high neutron fluxes, a large neutron multiplication factor suppression effect can be provided, thereby enabling to reduce the number of burnable poison rods relative to fuels. As a result, power peaking in the fuel assembly is moderated and a greater amount of plutonium can be loaded. In addition the flow of cooling water which tends to gather around the large diameter water rod can be controlled to improve cooling performance of fuels. (N.H.)
Position Control of a 3-CPU Spherical Parallel Manipulator
Directory of Open Access Journals (Sweden)
Massimo Callegari
2013-01-01
Full Text Available The paper presents the first experimental results on the control of a prototypal robot designed for the orientation of parts or tools. The innovative machine is a spherical parallel manipulator actuated by 3 linear motors; several position control schemes have been tested and compared with the final aim of designing an interaction controller. The relative simplicity of machine kinematics allowed to test algorithms requiring the closed-loop evaluation of both inverse and direct kinematics; the compensation of gravitational terms has been experimented as well.
Weld evaluation on spherical pressure vessels using holographic interferometry
International Nuclear Information System (INIS)
Boyd, D.M.; Wilcox, W.W.
1980-01-01
Waist welds on spherical experimental pressure vessels have been evaluated under pressure using holographic interferometry. A coincident viewing and illumination optical configuration coupled with a parabolic mirror was used so that the entire weld region could be examined with a single hologram. Positioning the pressure vessel at the focal point of the parabolic mirror provides a relatively undistorted 360 degree view of the waist weld. Double exposure and real time holography were used to obtain displacement information on the weld region. Results are compared with radiographic and ultrasonic inspections
Spherical tuned liquid damper for vibration control in wind turbines
DEFF Research Database (Denmark)
Chen, Jun-Ling; Georgakis, Christos T.
2015-01-01
table. The experimental results indicated that the spherical TLD could effectively improve the damping capacity of the test model. The standard deviation of the dynamic response could be effectively reduced when the excitation frequency was approximately equal to its fundamental frequency. For overspeed...... and extreme operating gust load cases, the standard deviations of the dynamic responses were reduced more than 40% when the liquid mass was about 2% of the generalized mass; for parking load cases, the corresponding standard deviation was reduced more than 50% when the liquid mass was only 1...
Numerical simulation of internal reconnection event in spherical tokamak
International Nuclear Information System (INIS)
Hayashi, Takaya; Mizuguchi, Naoki; Sato, Tetsuya
1999-07-01
Three-dimensional magnetohydrodynamic simulations are executed in a full toroidal geometry to clarify the physical mechanisms of the Internal Reconnection Event (IRE), which is observed in the spherical tokamak experiments. The simulation results reproduce several main properties of IRE. Comparison between the numerical results and experimental observation indicates fairly good agreements regarding nonlinear behavior, such as appearance of localized helical distortion, appearance of characteristic conical shape in the pressure profile during thermal quench, and subsequent appearance of the m=2/n=1 type helical distortion of the torus. (author)
Behaviour modelling of two aluminas in divergent spherical pyrotechnical experiments
International Nuclear Information System (INIS)
Malaise, F.; Tranchet, J.Y.; Collombet, F.
1997-01-01
Two pure aluminas of different characteristics have been subjected to the propagation of a longitudinal divergent spherical shock wave through pyrotechnical experiments. An approach combining a phenomenological analysis and numerical 1D-calculations is proposed to study the behaviour of these aluminas submitted to that type of wave loading. The modelling, proposed in a previous paper, is refined and gives satisfying experimentation-calculation correlations. An analysis of the influence exerted by the various encountered phenomena (plastic activity, pore closure, microcracking) is performed. The significant consequence of the activation of damage with an extension criterion is also underlined. (orig.)
Characteristics Verification of an Independently Controllable Electromagnetic Spherical Motor
Directory of Open Access Journals (Sweden)
Shuhei Maeda
2014-06-01
Full Text Available We have been developing electromagnetic spherical actuators capable of three-degree-of-freedom rotation. However, these actuators require complex control to realize simultaneous triaxial drive, because rotation around one axis interferes with rotation around another. In this paper, we propose a new three-degree-of-freedom actuator where 3-axes rotation can be controlled easily. The basic structure and the operating principle of the actuator are described. Then the torque characteristics and the dynamic characteristics are computed by employing 3D-FEM and the effectiveness of this actuator is clarified. Finally, the experimental results using the prototype of the actuator are shown to verify the dynamic performance.
Inducing Lift on Spherical Particles by Traveling Magnetic Fields
Mazuruk, Konstantin; Grugel, Richard N.; Rose, M. Franklin (Technical Monitor)
2001-01-01
Gravity induced sedimentation of suspensions is a serious drawback to many materials and biotechnology processes, a factor that can, in principle, be overcome by utilizing an opposing Lorentz body force. In this work we demonstrate the utility of employing a traveling magnetic field (TMF) to induce a lifting force on particles dispersed in the fluid. Theoretically, a model has been developed to ascertain the net force, induced by TMF, acting on a spherical body as a function of the fluid medium's electrical conductivity and other parameters. Experimentally, the model is compared to optical observations of particle motion in the presence of TMF.
Simulation of microtearing turbulence in national spherical torus experiment
Energy Technology Data Exchange (ETDEWEB)
Guttenfelder, W.; Kaye, S. M.; Bell, R. E.; Hammett, G. W.; LeBlanc, B. P.; Mikkelsen, D. R.; Ren, Y. [Princeton Plasma Physics Laboratory, Princeton New Jersey 08543 (United States); Candy, J. [General Atomics, San Diego, California 92186 (United States); Nevins, W. M.; Wang, E. [Lawrence Livermore National Laboratory, Livermore, California 04551 (United States); Zhang, J.; Crocker, N. A. [University of California Los Angeles, California 90095 (United States); Yuh, H. [Nova Photonics Inc., Princeton, New Jersey 08540 (United States)
2012-05-15
Thermal energy confinement times in National Spherical Torus Experiment (NSTX) dimensionless parameter scans increase with decreasing collisionality. While ion thermal transport is neoclassical, the source of anomalous electron thermal transport in these discharges remains unclear, leading to considerable uncertainty when extrapolating to future spherical tokamak (ST) devices at much lower collisionality. Linear gyrokinetic simulations find microtearing modes to be unstable in high collisionality discharges. First non-linear gyrokinetic simulations of microtearing turbulence in NSTX show they can yield experimental levels of transport. Magnetic flutter is responsible for almost all the transport ({approx}98%), perturbed field line trajectories are globally stochastic, and a test particle stochastic transport model agrees to within 25% of the simulated transport. Most significantly, microtearing transport is predicted to increase with electron collisionality, consistent with the observed NSTX confinement scaling. While this suggests microtearing modes may be the source of electron thermal transport, the predictions are also very sensitive to electron temperature gradient, indicating the scaling of the instability threshold is important. In addition, microtearing turbulence is susceptible to suppression via sheared E Multiplication-Sign B flows as experimental values of E Multiplication-Sign B shear (comparable to the linear growth rates) dramatically reduce the transport below experimental values. Refinements in numerical resolution and physics model assumptions are expected to minimize the apparent discrepancy. In cases where the predicted transport is strong, calculations suggest that a proposed polarimetry diagnostic may be sensitive to the magnetic perturbations associated with the unique structure of microtearing turbulence.
International Nuclear Information System (INIS)
Kumar, A.; Youssef, M.; Abdou, M.A.
1998-01-01
Within the framework of the ITER Task T-218 entitled 'Shielding Blanket Neutronics Experiments', nuclear heating measurements were conducted jointly by the USA and Japan using a micro calorimetric technique in a graphite-cantered assembly. An accelerator-based D-T neutron source at JAERI was used to provide a mixed neutron and photon field. The first measurements related to direct micro calorimetric measurements in individual graphite probes along the axis. In the second set, the first graphite probe was replaced, one by one, by single probes of beryllium, aluminum, silicon, silicon carbide, titanium, vanadium, chromium, iron, stainless steel 316, nickel, copper, zirconium, niobium, molybdenum, tungsten. Analysis of the measurements has been carried out using Monte Carlo code MCNP with FENDL-1, ENDF/B-VI and MCPLIB nuclear data libraries. A comparison of calculations (C) and experiments (E) shows a C/E ratio lying in a C/E band extending from 0.9 to 1.2 for beryllium, graphite, copper, chromium, iron, nickel, 316 stainless steel, titanium, vanadium, molybdenum, niobium and tungsten. However, larger deviations from unity are seen for C/E values for silicon, zirconium, and aluminum. Though FENDL-1 and ENDF/B-VI libraries provide very close nuclear heating rates for most of the probe materials, significant divergences are seen for silicon, silicon carbide, aluminum, titanium, zirconium, niobium, and molybdenum. The divergences are traceable to differences in neutron kerma factors as well as gamma production cross-sections of these materials. (orig.)
International Nuclear Information System (INIS)
Iijima, S.; Obu, M.; Hayase, T.; Ohno, A.; Nemoto, T.; Okajima, S.
1988-01-01
Power distributions of the large-scale axially heterogeneous liquid-metal fast breeder reactor were studied by using the experiment results of fast critical assemblies XI, XII, and XIII and the results of their analyses. The power distributions were examined by the gamma-scanning method and fission rate measurements using /sup 239/Pu and /sup 238/U fission counters and the foil irradiation method. In addition to the measurements in the reference core, the power distributions were measured in the core with a control rod inserted and in a modified core where the shape of the internal blanket was determined by the radial boundary. The calculation was made by using JENDL-2 and the Japan Atomic Energy Research Institute's standard calculation system for fast reactor neutronics. The power flattening trend, caused by the decrease of the fast neutron flux, was observed in the axial and radial power distributions. The effect of the radial boundary shape of the internal blanket on the power distribution was determined in the core. The thickness of the internal blanket was reduced at its radial boundary. The influence of the internal blanket was observed in the power distributions in the core with a control rod inserted. The calculation predicted the neutron spectrum harder in the internal blanket. In the radial distributions of /sup 239/Pu fission rates, the space dependency of the calculated-to-experiment values was found at the active core close to the internal blanket
Superlattices assembled through shape-induced directional binding
Lu, Fang; Yager, Kevin G.; Zhang, Yugang; Xin, Huolin; Gang, Oleg
2015-04-01
Organization of spherical particles into lattices is typically driven by packing considerations. Although the addition of directional binding can significantly broaden structural diversity, nanoscale implementation remains challenging. Here we investigate the assembly of clusters and lattices in which anisotropic polyhedral blocks coordinate isotropic spherical nanoparticles via shape-induced directional interactions facilitated by DNA recognition. We show that these polyhedral blocks--cubes and octahedrons--when mixed with spheres, promote the assembly of clusters with architecture determined by polyhedron symmetry. Moreover, three-dimensional binary superlattices are formed when DNA shells accommodate the shape disparity between nanoparticle interfaces. The crystallographic symmetry of assembled lattices is determined by the spatial symmetry of the block's facets, while structural order depends on DNA-tuned interactions and particle size ratio. The presented lattice assembly strategy, exploiting shape for defining the global structure and DNA-mediation locally, opens novel possibilities for by-design fabrication of binary lattices.
Chen, Rui; Nuhfer, Noel T; Moussa, Laura; Morris, Hannah R; Whitmore, Paul M
2008-11-12
A fast, simple procedure is described for obtaining an assembly of silver sulfide nanoparticles (Ag(2)S NPs) on a glass substrate through reaction of a template of an assembled layer of silver nanoparticles (Ag NPs) with hydrogen sulfide (H(2)S) gas. The Ag NP template was prepared by assembling a monolayer of spherical Ag NPs (mean diameter of 7.4 nm) on a polyethylenimine-treated glass substrate. Exposure to pure H(2)S for 10 min converted the Ag NPs of the template to Ag(2)S NPs. The resulting Ag(2)S NP assembly, which retains the template nanostructure and particle distribution, was characterized by optical absorption spectroscopy, atomic force microscopy, transmission electron microscopy (TEM), scanning high resolution TEM, energy dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. The Ag(2)S NPs have a crystal structure of monoclinic acanthite, and while they retained the spherical shape of the original Ag NPs, their mean particle size increased to 8.4 nm due to changes to the crystal structure when the Ag NPs are converted into Ag(2)S NPs. The measured optical absorption edge of the Ag(2)S NP assembly indicated an indirect interband transition with a band gap energy of 1.71 eV. The Ag(2)S NP assembly absorbed light with wavelengths below 725 nm, and the absorbance increased monotonically toward the UV region.
Thermo-mechanical screening tests to qualify beryllium pebble beds with non-spherical pebbles
Energy Technology Data Exchange (ETDEWEB)
Reimann, Joerg, E-mail: joerg.reimann@partner.kit.edu [IKET, Karlsruhe Institute of Technology, Karlsruhe (Germany); Fretz, Benjamin [KBHF GmbH, Eggenstein-Leopoldshafen (Germany); Pupeschi, Simone [IAM, Karlsruhe Institute of Technology, Karlsruhe (Germany)
2015-10-15
Highlights: • In present ceramic breeder blankets, pebble-shaped beryllium is used as a neutron multiplier. • Spherical pebbles are considered as the candidate material, however, non-spherical particles are of economic interest. • Thermo-mechanical pebble bed data do merely exist for non-spherical beryllium grades. • Uniaxial compression tests (UCTs), combined with the Hot Wire Technique (HWT) were used to measure the stress–strain relations and the thermal conductivity. • A small experimental set-up had to be used and a detailed 3D modelling was of prime importance. • Compared to spherical pebble beds, non-spherical pebble beds are generally softer and mainly the thermal conductivity is lower. - Abstract: In present ceramic breeder blankets, pebble-shaped beryllium is used as a neutron multiplier. Fairly spherical pebbles are considered as a candidate material, however, non-spherical particles are of economic interest because production costs are much lower. Yet, thermo-mechanical pebble bed data do merely exist for these beryllium grades, and the blanket relevant potential of these grades cannot be judged. Screening experiments were performed with three different grades of non-spherical beryllium pebbles, produced by different companies, accompanied by experiments with the reference beryllium pebble beds. Uniaxial compression tests (UCTs), combined with the Hot Wire Technique (HWT), were performed to measure both the stress–strain relation and the thermal conductivity, k, at different stress levels. Because of the limited amounts of the non-spherical materials, the experimental set-ups were small and a detailed 3D modelling was of prime importance in order to prove that the used design was appropriate. Compared to the pebble beds consisting of spherical pebbles, non-spherical pebble beds are generally softer (smaller stress for a given strain), and, mainly as a consequence of this, for a given strain value, the thermal conductivity is lower. This
ELSA- The European Levitated Spherical Actruator
Ruiz, M.; Serin, J.; Telteu-Nedelcu, D.; De La Vallee Poussin, H.; Onillon, E.; Rossini, L.
2014-08-01
The reaction sphere is a magnetic bearing spherical actuator consisting of a permanent magnet spherical rotor that can be accelerated in any direction. It consists of an 8-pole permanent magnet spherical rotor that is magnetically levitated and can be accelerated about any axis by a 20-pole stator with electromagnets. The spherical actuator is proposed as a potential alternative to traditional momentum exchange devices such as reaction wheels (RWs) or control moment gyroscopes (CMGs). This new actuator provides several benefits such as reduced mass and power supply allocated to the attitude and navigation unit, performance gain, and improved reliability due to the absence of mechanical bearings. The paper presents the work done on the levitated spherical actuator and more precisely the electrical drive including its control unit and power parts. An elegant breadboard is currently being manufactured within the frame of an FP7 project. This project also comprises a feasibility study to show the feasibility of integrating such a system on a flight platform and to identify all the challenges to be solved in terms of technology or components to be developed.
Statistical Mechanics of Thin Spherical Shells
Directory of Open Access Journals (Sweden)
Andrej Košmrlj
2017-01-01
Full Text Available We explore how thermal fluctuations affect the mechanics of thin amorphous spherical shells. In flat membranes with a shear modulus, thermal fluctuations increase the bending rigidity and reduce the in-plane elastic moduli in a scale-dependent fashion. This is still true for spherical shells. However, the additional coupling between the shell curvature, the local in-plane stretching modes, and the local out-of-plane undulations leads to novel phenomena. In spherical shells, thermal fluctuations produce a radius-dependent negative effective surface tension, equivalent to applying an inward external pressure. By adapting renormalization group calculations to allow for a spherical background curvature, we show that while small spherical shells are stable, sufficiently large shells are crushed by this thermally generated “pressure.” Such shells can be stabilized by an outward osmotic pressure, but the effective shell size grows nonlinearly with increasing outward pressure, with the same universal power-law exponent that characterizes the response of fluctuating flat membranes to a uniform tension.
Spherical aberrations of human astigmatic corneas.
Zhao, Huawei; Dai, Guang-Ming; Chen, Li; Weeber, Henk A; Piers, Patricia A
2011-11-01
To evaluate whether the average spherical aberration of human astigmatic corneas is statistically equivalent to human nonastigmatic corneas. Spherical aberrations of 445 astigmatic corneas prior to laser vision correction were retrospectively investigated to determine Zernike coefficients for central corneal areas 6 mm in diameter using CTView (Sarver and Associates). Data were divided into groups according to cylinder power (0.01 to 0.25 diopters [D], 0.26 to 0.75 D, 0.76 to 1.06 D, 1.07 to 1.53 D, 1.54 to 2.00 D, and >2.00 D) and according to age by decade. Spherical aberrations were correlated with age and astigmatic power among groups and the entire population. Statistical analyses were conducted, and P.05 for all tested groups). Mean spherical aberration of astigmatic corneas was not correlated significantly with cylinder power or age (P>.05). Spherical aberrations are similar to those of nonastigmatic corneas, permitting the use of these additional data in the design of aspheric toric intra-ocular lenses. Copyright 2011, SLACK Incorporated.
Recent Progress on Spherical Torus Research
Energy Technology Data Exchange (ETDEWEB)
Ono, Masayuki [PPPL; Kaita, Robert [PPPL
2014-01-01
The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio (A = R0/a) reduced to A ~ 1.5, well below the normal tokamak operating range of A ≥ 2.5. As the aspect ratio is reduced, the ideal tokamak beta β (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as β ~ 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural elongation κ, which makes its plasma shape appear spherical, the ST configuration can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to its longer term goal of attractive fusion energy power source. Since the start of the two megaampere class ST facilities in 2000, National Spherical Torus Experiment (NSTX) in the US and Mega Ampere Spherical Tokamak (MAST) in UK, active ST research has been conducted worldwide. More than sixteen ST research facilities operating during this period have achieved remarkable advances in all of fusion science areas, involving fundamental fusion energy science as well as innovation. These results suggest exciting future prospects for ST research both near term and longer term. The present paper reviews the scientific progress made by the worldwide ST research community during this new mega-ampere-ST era.
The spherical harmonics method, II (application to problems with plane and spherical symmetry)
Energy Technology Data Exchange (ETDEWEB)
Mark, C
1958-12-15
The application of the spherical harmonic method to problems with plane or spherical symmetry is discussed in detail. The numerical results of some applications already made are included to indicate the degree of convergence obtained. Formulae for dealing with distributions of isotropic sources are developed. Tables useful in applying the method are given in Section 11. (author)
International Nuclear Information System (INIS)
Fujibayashi, Toru.
1970-01-01
Herein disclosed is a fuel assembly in which a fuel rod bundle is easily detachable by rotating a fuel rod fastener rotatably mounted to the upper surface of an upper tie-plate supporting a fuel bundle therebelow. A locking portion at the leading end of each fuel rod protrudes through the upper tie-plate and is engaged with or separated from the tie-plate by the rotation of the fastener. The removal of a desired fuel rod can therefore be remotely accomplished without the necessity of handling pawls, locking washers and nuts. (Owens, K.J.)
DEFF Research Database (Denmark)
Assembling Consumption marks a definitive step in the institutionalisation of qualitative business research. By gathering leading scholars and educators who study markets, marketing and consumption through the lenses of philosophy, sociology and anthropology, this book clarifies and applies...... the investigative tools offered by assemblage theory, actor-network theory and non-representational theory. Clear theoretical explanation and methodological innovation, alongside empirical applications of these emerging frameworks will offer readers new and refreshing perspectives on consumer culture and market...... societies. This is an essential reading for both seasoned scholars and advanced students of markets, economies and social forms of consumption....
Electromagnetic cloaking in higher order spherical cloaks
Sidhwa, H. H.; Aiyar, R. P. R. C.; Kulkarni, S. V.
2017-06-01
The inception of transformation optics has led to the realisation of the invisibility devices for various applications, one of which is spherical cloaking. In this paper, a formulation for a higher-order spherical cloak has been proposed to reduce its physical thickness significantly by introducing a nonlinear relation between the original and transformed coordinate systems and it has been verified using the ray tracing approach. Analysis has been carried out to observe the anomalies in the variation of refractive index for higher order cloaks indicating the presence of poles in the relevant equations. Furthermore, a higher-order spherical cloak with predefined values of the material characteristics on its inner and outer surfaces has been designed for practical application.
A spherical Taylor-Couette dynamo
Marcotte, Florence; Gissinger, Christophe
2016-04-01
We present a new scenario for magnetic field amplification in the planetary interiors where an electrically conducting fluid is confined in a differentially rotating, spherical shell (spherical Couette flow) with thin aspect-ratio. When the angular momentum sufficiently decreases outwards, a primary hydrodynamic instability is widely known to develop in the equatorial region, characterized by pairs of counter-rotating, axisymmetric toroidal vortices (Taylor vortices) similar to those observed in cylindrical Couette flow. We characterize the subcritical dynamo bifurcation due to this spherical Taylor-Couette flow and study its evolution as the flow successively breaks into wavy and turbulent Taylor vortices for increasing Reynolds number. We show that the critical magnetic Reynolds number seems to reach a constant value as the Reynolds number is gradually increased. The role of global rotation on the dynamo threshold and the implications for planetary interiors are finally discussed.
Spherical tokamak power plant design issues
International Nuclear Information System (INIS)
Hender, T.C.; Bond, A.; Edwards, J.; Karditsas, P.J.; McClements, K.G.; Mustoe, J.; Sherwood, D.V.; Voss, G.M.; Wilson, H.R.
2000-01-01
The very high β potential of the spherical tokamak has been demonstrated in the START experiment. Systems code studies show the cost of electricity from spherical tokamak power plants, operating at high β in second ballooning mode stable regime, is comparable with fossil fuels and fission. Outline engineering designs are presented based on two concepts for the central rod of the toroidal field (TF) circuit - a room temperature water cooled copper rod or a helium cooled cryogenic aluminium rod. For the copper rod case the TF return limbs are supported by the vacuum vessel, while for the aluminium rod the TF coils form an independent structure. In both cases thermohydraulic and stress calculations indicate the viability of the design. Two-dimensional neutronics calculations show the feasibility of tritium self-sufficiency without an inboard blanket. The spherical tokamak has unique maintenance possibilities based on lowering major component structures into a hot cell beneath the device and these are discussed
Dynamics of a spherical minority game
International Nuclear Information System (INIS)
Galla, T; Coolen, A C C; Sherrington, D
2003-01-01
We present an exact dynamical solution of a spherical version of the batch minority game (MG) with random external information. The control parameters in this model are the ratio of the number of possible values for the public information over the number of agents, and the radius of the spherical constraint on the microscopic degrees of freedom. We find a phase diagram with three phases: two without anomalous response (an oscillating versus a frozen state) and a further frozen phase with divergent integrated response. In contrast to standard MG versions, we can also calculate the volatility exactly. Our study reveals similarities between the spherical and the conventional MG, but also intriguing differences. Numerical simulations confirm our analytical results
Elastic properties of spherically anisotropic piezoelectric composites
International Nuclear Information System (INIS)
En-Bo, Wei; Guo-Qing, Gu; Ying-Ming, Poon
2010-01-01
Effective elastic properties of spherically anisotropic piezoelectric composites, whose spherically anisotropic piezoelectric inclusions are embedded in an infinite non-piezoelectric matrix, are theoretically investigated. Analytical solutions for the elastic displacements and the electric potentials under a uniform external strain are derived exactly. Taking into account of the coupling effects of elasticity, permittivity and piezoelectricity, the formula is derived for estimating the effective elastic properties based on the average field theory in the dilute limit. An elastic response mechanism is revealed, in which the effective elastic properties increase as inclusion piezoelectric properties increase and inclusion dielectric properties decrease. Moreover, a piezoelectric response mechanism, of which the effective piezoelectric response vanishes due to the symmetry of spherically anisotropic composite, is also disclosed. (condensed matter: structure, thermal and mechanical properties)
International Nuclear Information System (INIS)
Kurihara, Kunitoshi; Azekura, Kazuo.
1992-01-01
In a reactor core of a heavy water moderated light water cooled pressure tube type reactor, no sufficient effects have been obtained for the transfer width to a negative side of void reactivity change in a region of a great void coefficient. Then, a moderation region divided into upper and lower two regions is disposed at the central portion of a fuel assembly. Coolants flown into the lower region can be discharged to the cooling region from an opening disposed at the upper end portion of the lower region. Light water flows from the lower region of the moderator region to the cooling region of the reactor core upper portion, to lower the void coefficient. As a result, the reactivity performance at low void coefficient, i.e., a void reaction rate is transferred to the negative side. Thus, this flattens the power distribution in the fuel assembly, increases the thermal margin and enables rapid operaiton and control of the reactor core, as well as contributes to the increase of fuel burnup ratio and reduction of the fuel cycle cost. (N.H.)
International Nuclear Information System (INIS)
Chaki, Masao; Nishida, Koji; Karasawa, Hidetoshi; Kanazawa, Toru; Orii, Akihito; Nagayoshi, Takuji; Kashiwai, Shin-ichi; Masuhara, Yasuhiro
1998-01-01
The present invention concerns a fuel assembly, for a BWR type nuclear reactor, comprising fuel rods in 9 x 9 matrix. The inner width of the channel box is about 132mm and the length of the fuel rods which are not short fuel rods is about 4m. Two water rods having a circular cross section are arranged on a diagonal line in a portion of 3 x 3 matrix at the center of the fuel assembly, and two fuel rods are disposed at vacant spaces, and the number of fuel rods is 74. Eight fuel rods are determined as short fuel rods among 74 fuel rods. Assuming the fuel inventory in the short fuel rod as X(kg), and the fuel inventory in the fuel rods other than the short fuel rods as Y(kg), X and Y satisfy the relation: X + Y ≥ 173m, Y ≤ - 9.7X + 292, Y ≤ - 0.3X + 203 and X > 0. Then, even when the short fuel rods are used, the fuel inventory is increased and fuel economy can be improved. (I.N.)
International Nuclear Information System (INIS)
Fushimi, Atsushi; Shimada, Hidemitsu; Aoyama, Motoo; Nakajima, Junjiro
1998-01-01
In a fuel assembly for an n x n lattice-like BWR type reactor, n is determined to 9 or greater, and the enrichment degree of plutonium is determined to 4.4% by weight or less. Alternatively, n is determined to 10 or greater, and the enrichment degree of plutonium is determined to 5.2% by weight or less. An average take-out burnup degree is determined to 39GWd/t or less, and the matrix is determined to 9 x 9 or more, or the average take-out burnup degree is determined to 51GWd/t, and the matrix is determined to 10 x 10 or more and the increase of the margin of the maximum power density obtained thereby is utilized for the compensation of the increase of distortion of power distribution due to decrease of the kinds of plutonium enrichment degree, thereby enabling to reduce the kind of the enrichment degree of MOX fuel rods to one. As a result, the manufacturing step for fuel pellets can be simplified to reduce the manufacturing cost for MOX fuel assemblies. (N.H.)
Staff Association
2015-01-01
Mardi 5 mai à 11 h 00 Salle 13-2-005 Conformément aux statuts de l’Association du personnel, une Assemblée générale ordinaire est organisée une fois par année (article IV.2.1). Projet d’ordre du jour : 1- Adoption de l’ordre du jour. 2- Approbation du procès-verbal de l’Assemblée générale ordinaire du 22 mai 2014. 3- Présentation et approbation du rapport d’activités 2014. 4- Présentation et approbation du rapport financier 2014. 5- Présentation et approbation du rapport des vérificateurs aux comptes pour 2014. 6- Programme 2015. 7- Présentation et approbation du projet de budget 2015 et taux de cotisation pour 2015. 8- Pas de modifications aux Statuts de l'Association du personnel proposée. 9- Élections des membres de la Commission é...
Staff Association
2017-01-01
Conformément aux statuts de l’Association du personnel, une Assemblée générale ordinaire est organisée une fois par année (article IV.2.1). Projet d’ordre du jour : Adoption de l’ordre du jour. Approbation du procès-verbal de l’Assemblée générale ordinaire du 5 avril 2016. Présentation et approbation du rapport d’activités 2016. Présentation et approbation du rapport financier 2016. Présentation et approbation du rapport des vérificateurs aux comptes pour 2016. Programme de travail 2017. Présentation et approbation du projet de budget 2017 Approbation du taux de cotisation pour 2018. Modifications aux Statuts de l'Association du personnel proposées. Élections des membres de la Commission électorale. Élections des vérifica...
Staff Association
2016-01-01
Mardi 5 avril à 11 h 00 BE Auditorium Meyrin (6-2-024) Conformément aux statuts de l’Association du personnel, une Assemblée générale ordinaire est organisée une fois par année (article IV.2.1). Projet d’ordre du jour : Adoption de l’ordre du jour. Approbation du procès-verbal de l’Assemblée générale ordinaire du 5 mai 2015. Présentation et approbation du rapport d’activités 2015. Présentation et approbation du rapport financier 2015. Présentation et approbation du rapport des vérificateurs aux comptes pour 2015. Programme de travail 2016. Présentation et approbation du projet de budget 2016 Approbation du taux de cotisation pour 2017. Modifications aux Statuts de l'Association du personnel proposée. Élections des membres de la Commissio...
Staff Association
2015-01-01
Mardi 5 mai à 11 h 00 Salle 13-2-005 Conformément aux statuts de l’Association du personnel, une Assemblée générale ordinaire est organisée une fois par année (article IV.2.1). Projet d’ordre du jour : Adoption de l’ordre du jour. Approbation du procès-verbal de l’Assemblée générale ordinaire du 22 mai 2014. Présentation et approbation du rapport d’activités 2014. Présentation et approbation du rapport financier 2014. Présentation et approbation du rapport des vérificateurs aux comptes pour 2014. Programme 2015. Présentation et approbation du projet de budget 2015 et taux de cotisation pour 2015. Pas de modifications aux Statuts de l'Association du personnel proposée. Élections des membres de la Commission électorale. &am...
International Nuclear Information System (INIS)
Nomata, Terumitsu.
1993-01-01
Among fuel pellets to be loaded to fuel cans of a fuel assembly, fuel pellets having a small thermal power are charged in a region from the end of each of spacers up to about 50mm on the upstream of coolants that flow vertically at the periphery of fuel rods. Coolants at the periphery of fuel rods are heated by the heat generation, to result in voids. However, since cooling effect on the upstream of the spacers is low due to influences of the spacers. Further, since the fuel pellets disposed in the upstream region have small thermal power, a void coefficient is not increased. Even if a thermal power exceeding cooling performance should be generated, there is no worry of causing burnout in the upstream region. Even if burnout should be caused, safety margin and reliability relative to burnout are improved, to increase an allowable thermal power, thereby enabling to improve integrity and reliability of fuel rods and fuel assemblies. (N.H.)
A neutronic assessment of the new Spherical Cermets Fuel concept for the BWR-PB reactor
International Nuclear Information System (INIS)
Benchrif, A.; Chetaine, A.; Amsil, H.; Bounakhla, M.
2010-01-01
The tri-structural-isotopic (TRISO) fuel directly cooled by boiling light water is used in the boiling water reactor with pebble-bed coated particles (BWR-PB). At the lower coolant temperature, the TRISO fuel particles demonstrate an unacceptable irradiation swelling in the silicon carbide coating layer during a fuel cycle. So, the objectives of this paper, on the one hand is to evaluate some neutronic parameters of a new fuel concept, Spherical Cermets Fuel (SCF), for a BWR-PB reactor. On the other hand, to assess the fact of SCF fuel concept on the fuel assembly lifetime and the burn-up characteristic. All the parameters as well as Infinite Multiplication Factor, Spectrum Index, Instantaneous Conversion Ratio and Neutron Energy Spectrum was calculated then compared for the TRISO and the SCF fuel concept. It can be seen from the assessment of fuel assembly burn-up characteristics that the normalised neutron spectra of all the assembly's parts pointed out a thermal spectrum for the SCF fuel assembly's parts than the TRISO one. The SCF fuel element increase the assembly life time about 6.1 EFPY corresponding 8000 MWd/t. So, the fuel assembly can be operated for a reasonably long period without outside refuelling. The difference in the assembly lifetime might leads to SCF fuel concept adopted, because the geometry and concept of TRISO fuel particles are wholly different to SCF ones. (author)
Analysis of a spherical permanent magnet actuator
International Nuclear Information System (INIS)
Wang, J.; Jewell, G.W.; Howe, D.
1997-01-01
This paper describes a new form of actuator with a spherical permanent magnet rotor and a simple winding arrangement, which is capable of a high specific torque by utilizing a rare-earth permanent magnet. The magnetic-field distribution is established using an analytical technique formulated in spherical coordinates, and the results are validated by finite element analysis. The analytical field solution allows the prediction of the actuator torque and back emf in closed forms. In turn, these facilitate the characterization of the actuator and provide a firm basis for design optimization, system dynamic modeling, and closed-loop control law development. copyright 1997 American Institute of Physics
Development of a spherical neutron rem monitor
International Nuclear Information System (INIS)
Panchal, C.G.; Madhavi, V.; Bansode, P.Y.; Jakati, R.K.; Ghodgaonkar, M.D.; Desai, S.S.; Shaikh, A.M.; Sathian, V.
2007-01-01
A new neutron rem monitor based on spherical LINUS with the state of art electronic circuits has been designed in Electronics Division. This prototype instrument encompasses a spherical double polythene moderator to improve an isotropic response and a lead layer to extend its energy response compared to the conventional neutron rem monitors. A systematic testing and calibration of the energy and directional response of the prototype monitor have been carried out. Although the monitor is expected to perform satisfactorily upto an energy ∼ 55 MeV, at present its response has been tested upto 5 MeV. (author)
Directory of Open Access Journals (Sweden)
Wenyi Huo
2016-01-01
Full Text Available The octahedral spherical hohlraums have natural superiority in maintaining high radiation symmetry during the entire capsule implosion process in indirect drive inertial confinement fusion. While, in contrast to the cylindrical hohlraums, the narrow space between the laser beams and the spherical hohlraum wall is usually commented. In this Letter, we address this crucial issue and report our experimental work conducted on the SGIII-prototype laser facility which unambiguously demonstrates that a simple design of cylindrical laser entrance hole (LEH can dramatically improve the laser propagation inside the spherical hohlraums. In addition, the laser beam deflection in the hohlraum is observed for the first time in the experiments. Our 2-dimensional simulation results also verify qualitatively the advantages of the spherical hohlraums with cylindrical LEHs. Our results imply the prospect of adopting the cylindrical LEHs in future spherical ignition hohlraum design.
International Nuclear Information System (INIS)
Jin, Congrui; Davoodabadi, Ali; Li, Jianlin; Wang, Yanli; Singler, Timothy
2017-01-01
Because of the development of novel micro-fabrication techniques to produce ultra-thin materials and increasing interest in thin biological membranes, in recent years, the mechanical characterization of thin films has received a significant amount of attention. To provide a more accurate solution for the relationship among contact radius, load and deflection, the fundamental and widely applicable problem of spherical indentation of a freestanding circular membrane have been revisited. The work presented here significantly extends the previous contributions by providing an exact analytical solution to the governing equations of Föppl–Hecky membrane indented by a frictionless spherical indenter. In this study, experiments of spherical indentation has been performed, and the exact analytical solution presented in this article is compared against experimental data from existing literature as well as our own experimental results.
Rotor dynamic studies of a vertical sodium pump supported on a spherical seat
International Nuclear Information System (INIS)
Asokkumar, S.; Ramalingam, P.; Baskar, S.; Balachander, K.; Kale, R.D.
1994-01-01
One of the important areas in the mechanical design of Primary Sodium Pumps (PSP) concerns with the problem of accommodating the differential thermal expansion between the pump support and the discharge pipe which function at substantially different temperatures. A spherical ball resting on a spherical split seat is designed to allow the tilting of the pump without creating significant stresses in the pump casing and the discharge pipe. To ascertain the dynamic performance of the pump and to validate the design, an experimental study was carried out with a 1/4 model spherical seat installed in an existing 50 cu.m/hr pump. The paper discusses the modeling criteria, details of theoretical/experimental studies and results obtained during testing. This paper also discusses details of full size test rig which is under construction. (author). 4 refs., 3 figs., 2 tabs
Control System Development Plan for the National Spherical Torus Experiment
International Nuclear Information System (INIS)
Neumeyer, C.; Mueller, D.; Gates, D.A.; Ferron, J.R.
1999-01-01
The National Spherical Torus Experiment (NSTX) has as one of its primary goals the demonstration of the attractiveness of the spherical torus concept as a fusion power plant. Central to this goal is the achievement of high plasma β ( = 2 micro 0 /B 2 a measure of the efficiency of a magnetic plasma confinement system). It has been demonstrated both theoretically and experimentally that the maximum achievable β is a strong function of both local and global plasma parameters. It is therefore important to optimize control of the plasma. To this end a phased development plan for digital plasma control on NSTX is presented. The relative level of sophistication of the control system software and hardware will be increased according to the demands of the experimental program in a three phase plan. During Day 0 (first plasma), a simple coil current control algorithm will initiate plasma operations. During the second phase (Day 1) of plasma operations the control system will continue to use the preprogrammed algorithm to initiate plasma breakdown but will then change over to a rudimentary plasma control scheme based on linear combinations of measured plasma fields and fluxes. The third phase of NSTX plasma control system development will utilize the rtEFIT code, first used on DIII-D, to determine, in real-time, the full plasma equilibrium by inverting the Grad-Shafranov equation. The details of the development plan, including a description of the proposed hardware will be presented
International Nuclear Information System (INIS)
Afanasiev, A.; Semishkin, V.; Makarov, V.; Matvienko, I.; Puzanov, D.
2015-01-01
generated for the consideration of TVS-2006 fuel assembly thermal-mechanical stability and its component shape deformation in loss-of-coolant accidents. The calculation results have shown that in the course of a design-basis loss-of-coolant accident TVS-2006 has a two-fold margin for stability loss at the longitudinal compression considering the increase in the force of FA compression due to thermal expansion of fuel rod bundle. The increase in the width across the flats is insignificant and it does not impede the post-accident core unloading. (authors) KEYWORDS: TVS- 2006, thermal-mechanical, shape deformation, modeling, loss of coolant
Directory of Open Access Journals (Sweden)
V. P. Lazarenko
2016-01-01
Full Text Available Subject of Study. The key feature of spherical panoramas is the maximum possible angle of view (360 × 180 degrees. Omnidirectional optical-electronic systems are able to produce images that show most of this space, but these images are different from the canonical spherical panoramas. This paper proposes a method of converting the circular images obtained by omnidirectional optical systems, to canonical spherical panoramic images with the use ofcalibration procedure of omnidirectional optical-electronic system. Method. The process of spherical panoramas creation consists of three steps.The first step includesthe forming of virtual surface in the object space corresponding to a field of view of the spherical panorama. The surface is defined by the three-dimensional array of pixels.At the second step the coordinates of images of these points in the plane of the detectorare specified. At the third step pixel-by-pixel forming of the output imageisperformed from the original omnidirectional image with the use of coordinates obtained at the second step. Main Results. We have considered the geometric projectionmodel of spherical panoramas. The algorithm has been proposed calculating the three-dimensional array of pixels, characterizing the field of view of a spherical panorama and convenient for practical usage. The developed method is designed to work with omnidirectional optical-electronic systems both with catadioptric optical systems and with fisheye lens. Experimental results confirming the validity of this method are presented. The reprojection mean-square error was equal to 0.794 px. Practical Relevance. The proposed method can be applied in technologies of creating of virtual tours or panoramas of streets where spherical panoramic images are the standard for storing visual information. The method may also find its application in various fields of robotics, orientation and navigation of space vehicles and UAVs.
International Nuclear Information System (INIS)
Ueda, Makoto; Ogiya, Shunsuke.
1989-01-01
For improving the economy of a BWR type reactor by making the operation cycle longer, the fuel enrichment degree has to be increased further. However, this makes the subcriticality shallower in the upper portion of the reactor core, to bring about a possibility that the reactor shutdown becomes impossible. In the present invention, a portion of fuel rod is constituted as partial length fuel rods (P-fuel rods) in which the entire stack length in the effective portion is made shorter by reducing the concentration of fissionable materials in the axial portion. A plurality of moderator rods are disposed at least on one diagonal line of a fuel assembly and P-fuel rods are arranged at a position put between the moderator rods. This makes it possible to reactor shutdown and makes the axial power distribution satisfactory even if the fuel enrichment degree is increased. (T.M.)
International Nuclear Information System (INIS)
Bando, Masaru.
1993-01-01
As neutron irradiation progresses on a fuel assembly of an FBR type reactor, a strong force is exerted to cause ruptures if the arrangement of fuel elements is not displaced, whereas the fuel elements may be brought into direct contact with each other not by way of spacers to cause burning damages if the arrangement is displaced. In the present invention, the circumference of fuel elements arranged in a normal triangle lattice is surrounded by a wrapper tube having a hexagonal cross section, wire spacers are wound therearound, and deformable spacers are distributed to optional positions for fuel elements in the wrapper tube. Interaction between the fuel elements caused by irradiation is effectively absorbed, thereby enabling to delay the occurrence of the rupture and burning damages of the elements. (N.H.)
International Nuclear Information System (INIS)
Ueda, Makoto.
1991-01-01
In a fuel assembly in which spectral shift type moderator guide members are arranged, the moderator guide member has a flow channel resistance member, that provides flow resistance against the moderators, in the upstream of a moderator flowing channel, by which the ratio of removing coolants is set greater at the upstream than downstream. With such a constitution, the void distribution increasing upward in the channel box except for the portion of the moderator guide member is moderated by the increase of the area of the void region that expands downward in the guide member. Accordingly, the axial power distribution is flattened throughout the operation cycle and excess distortion is eliminated to improve the fuel integrity. (T.M.)
International Nuclear Information System (INIS)
Wataumi, Kazutoshi; Tajiri, Hiroshi.
1992-01-01
In a fuel assembly of a BWR type reactor, a pellet to be loaded comprises an external layer of fissile materials containing burnable poisons and an internal layer of fissile materials not containing burnable poison. For example, there is provided a dual type pellet comprising an external layer made of UO 2 incorporated with Gd 2 O 3 at a predetermined concentration as the burnable poisons and an internal layer made of UO 2 not containing Gd 2 O 3 . The amount of the burnable poisons required for predetermined places is controlled by the thickness of the ring of the external layer. This can dissipate an unnecessary poisoning effect at the final stage of the combustion cycle. Further, since only one or a few kinds of powder mixture of the burnable poisons and the fissile materials is necessary, production and product control can be facilitated. (I.N.)
International Nuclear Information System (INIS)
Ishibashi, Yoko; Aoyama, Motoo; Oyama, Jun-ichi.
1995-01-01
Burnable poison-incorporating fuel rods of a first group are disposed in a region in adjacent with a water rod having a large diameter (neutron moderator rod) disposed to the central portion of a fuel assembly. Burnable poison-incorporating fuel rods of a second group are disposed to a region other than peripheral zone in adjacent with a channel box and corners positioned at an inner zone, in adjacent with the channel box. The average concentration of burnable poisons of the burnable poison-incorporating fuel rods of the first group is made greater than that of the second group. With such a constitution, when the burnable poisons of the first group are burnt out, the burnable poisons of the second group are also burnt out at the same time. Accordingly, an amount of burnable poisons left unburnt at the final stage of the operation cycle is reduced, to improve the reactivity. This can improve the economical property. (I.N.)
International Nuclear Information System (INIS)
Yoshioka, Ritsuo.
1983-01-01
Purpose: To improve the operation performance of a BWR type reactor by improving the distribution of the uranium enrichment and the incorporation amount of burnable poisons in fuel assemblies. Constitution: The average enrichment of uranium 235 is increased in the upper portion as compared with that in the lower portion, while the incorporation amount of burnable poisons is increased in an upper portion as compared with that in the lower portion. The difference in the incorporation amount of the burnable poisons between the upper and lower portions is attained by charging two kinds of fuel rods; the ones incorporated with the burnable poisons over the entire length and the others incorporated with the burnable poisons only in the upper portions. (Seki, T.)
Towards Crystals of Crystals of NanoCrystals : a Self-Assembly Study
de Nijs, B.
2014-01-01
In this thesis several methods to synthesise monodisperse nanoparticles and how to self-assembled them within emulsion droplets are presented. The self-assembly behaviour of nanoparticles within the spherical confinement of emulsion droplets resulted in highly ordered crystalline supraparticles that
Novel Electrically Small Spherical Electric Dipole Antenna
DEFF Research Database (Denmark)
Kim, Oleksiy S.
2010-01-01
This paper introduces a novel electrically small spherical meander antenna. Horizontal sections of the meander are composed of wire loops, radii of which are chosen so that the whole structure is conformal to a sphere of radius a. To form the meander the loops are connected by wires at a meridian...
Preparations of spherical polymeric particles from Tanzanian ...
African Journals Online (AJOL)
Spherical Polymeric Particles (SPP) have been prepared from Tanzanian Cashew Nut Shell Liquid (CNSL) by suspension polymerization technique involving either step-growth or chain- growth polymerization mechanisms. The sizes of the SPP, which ranged from 0.1 to 2.0 mm were strongly influenced by the amounts of ...
Sphericity in the interacting boson model
International Nuclear Information System (INIS)
Ogata, H.
1977-01-01
The interacting boson model (IBM) of Arima and Iachello is examined. The transition between the rotational and vibrational modes of even-even nuclei is presented as a function of a sphericity parameter, which is determined primarily from yrast band spectra. The backbending feature is reasonably reproduced. (author)
Exact solutions of the spherically symmetric multidimensional ...
African Journals Online (AJOL)
The complete orthonormalised energy eigenfunctions and the energy eigenvalues of the spherically symmetric isotropic harmonic oscillator in N dimensions, are obtained through the methods of separation of variables. Also, the degeneracy of the energy levels are examined. KEY WORDS: - Schrödinger Equation, Isotropic ...
Added Mass of a Spherical Cap Body
Czech Academy of Sciences Publication Activity Database
Šimčík, Miroslav; Punčochář, Miroslav; Růžička, Marek
2014-01-01
Roč. 118, OCT 18 (2014), s. 1-8 ISSN 0009-2509 R&D Projects: GA MŠk(CZ) LD13018 Institutional support: RVO:67985858 Keywords : spherical cap * added mass * single particle Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.337, year: 2014
Effective pair potentials for spherical nanoparticles
International Nuclear Information System (INIS)
Van Zon, Ramses
2009-01-01
An effective description for rigid spherical nanoparticles in a fluid of point particles is presented. The points inside the nanoparticles and the point particles are assumed to interact via spherically symmetric additive pair potentials, while the distribution of points inside the nanoparticles is taken to be spherically symmetric and smooth. The resulting effective pair interactions between a nanoparticle and a point particle, as well as between two nanoparticles, are then given by spherically symmetric potentials. If overlap between particles is allowed, as can occur for some forms of the pair potentials, the effective potential generally has non-analytic points. It is shown that for each effective potential the expressions for different overlapping cases can be written in terms of one analytic auxiliary potential. Even when only non-overlapping situations are possible, the auxiliary potentials facilitate the formulation of the effective potentials. Effective potentials for hollow nanoparticles (appropriate e.g. for buckyballs) are also considered and shown to be related to those for solid nanoparticles. For hollow nanoparticles overlap is more physical, since this covers the case of a smaller particle embedded in a larger, hollow nanoparticle. Finally, explicit expressions are given for the effective potentials derived from basic pair potentials of power law and exponential form, as well as from the commonly used London–van der Waals, Morse, Buckingham, and Lennard-Jones potentials. The applicability of the latter is demonstrated by comparison with an atomic description of nanoparticles with an internal face centered cubic structure
MAST: a Mega Amp Spherical Tokamak
International Nuclear Information System (INIS)
Darke, A.C.; Harbar, J.R.; Hay, J.H.; Hicks, J.B.; Hill, J.W.; McKenzie, J.S.; Morris, A.W.; Nightingale, M.P.S.; Todd, T.N.; Voss, G.M.; Watkins, J.R.
1995-01-01
The highly successful tight aspect ratio tokamak research pioneered on the START machine at Culham, together with the attractive possibilities of the concept, suggest a larger device should be considered. The design of a Mega Amp Spherical Tokamak is described, operating at much higher currents and over longer pulses than START and compatible with strong additional heating. (orig.)
A Generalization of the Spherical Inversion
Ramírez, José L.; Rubiano, Gustavo N.
2017-01-01
In the present article, we introduce a generalization of the spherical inversion. In particular, we define an inversion with respect to an ellipsoid, and prove several properties of this new transformation. The inversion in an ellipsoid is the generalization of the elliptic inversion to the three-dimensional space. We also study the inverse images…
Sparse acoustic imaging with a spherical array
DEFF Research Database (Denmark)
Fernandez Grande, Efren; Xenaki, Angeliki
2015-01-01
In recent years, a number of methods for sound source localization and sound field reconstruction with spherical microphone arrays have been proposed. These arrays have properties that are potentially very useful, e.g. omni-directionality, robustness, compensable scattering, etc. This paper propo...
Spherical torus, compact fusion at low field
International Nuclear Information System (INIS)
Peng, Y.K.M.
1985-02-01
A spherical torus is obtained by retaining only the indispensable components on the inboard side of a tokamak plasma, such as a cooled, normal conductor that carries current to produce a toroidal magnetic field. The resulting device features an exceptionally small aspect ratio (ranging from below 2 to about 1.3), a naturally elongated D-shaped plasma cross section, and ramp-up of the plasma current primarily by noninductive means. As a result of the favorable dependence of the tokamak plasma behavior to decreasing aspect ratio, a spherical torus is projected to have small size, high beta, and modest field. Assuming Mirnov confinement scaling, an ignition spherical torus at a field of 2 T features a major radius of 1.5 m, a minor radius of 1.0 m, a plasma current of 14 MA, comparable toroidal and poloidal field coil currents, an average beta of 24%, and a fusion power of 50 MW. At 2 T, a Q = 1 spherical torus will have a major radius of 0.8 m, a minor radius of 0.5 m, and a fusion power of a few megawatts
Olvera de La Cruz, Monica; Sayar, Mehmet; Solis, Francisco J.; Stupp, Samuel I.
2001-03-01
Recent experimental studies in our group have shown that self assembled thin films of noncentrosymmetric supramolecular objects composed of triblock rodcoil molecules exhibit finite polar order. These aggregates have both long range dipolar and short range Ising-like interactions. We study the ground state of a simple model with these competing interactions. We find that the competition between Ising-like and dipolar forces yield a periodic domain structure, which can be controlled by adjusting the force constants and film thickness. When the surface forces are included in the potential, the system exhibits a finite macroscopic polar order.
First Octahedral Spherical Hohlraum Energetics Experiment at the SGIII Laser Facility
Huo, Wen Yi; Li, Zhichao; Chen, Yao-Hua; Xie, Xufei; Ren, Guoli; Cao, Hui; Li, Shu; Lan, Ke; Liu, Jie; Li, Yongsheng; Li, Sanwei; Guo, Liang; Liu, Yonggang; Yang, Dong; Jiang, Xiaohua; Hou, Lifei; Du, Huabing; Peng, Xiaoshi; Xu, Tao; Li, Chaoguang; Zhan, Xiayu; Wang, Zhebin; Deng, Keli; Wang, Qiangqiang; Deng, Bo; Wang, Feng; Yang, Jiamin; Liu, Shenye; Jiang, Shaoen; Yuan, Guanghui; Zhang, Haijun; Jiang, Baibin; Zhang, Wei; Gu, Qianqian; He, Zhibing; Du, Kai; Deng, Xuewei; Zhou, Wei; Wang, Liquan; Huang, Xiaoxia; Wang, Yuancheng; Hu, Dongxia; Zheng, Kuixing; Zhu, Qihua; Ding, Yongkun
2018-04-01
The first octahedral spherical hohlraum energetics experiment is accomplished at the SGIII laser facility. For the first time, the 32 laser beams are injected into the octahedral spherical hohlraum through six laser entrance holes. Two techniques are used to diagnose the radiation field of the octahedral spherical hohlraum in order to obtain comprehensive experimental data. The radiation flux streaming out of laser entrance holes is measured by six flat-response x-ray detectors (FXRDs) and four M -band x-ray detectors, which are placed at different locations of the SGIII target chamber. The radiation temperature is derived from the measured flux of FXRD by using the blackbody assumption. The peak radiation temperature inside hohlraum is determined by the shock wave technique. The experimental results show that the octahedral spherical hohlraum radiation temperature is in the range of 170-182 eV with drive laser energies of 71 kJ to 84 kJ. The radiation temperature inside the hohlraum determined by the shock wave technique is about 175 eV at 71 kJ. For the flat-top laser pulse of 3 ns, the conversion efficiency of gas-filled octahedral spherical hohlraum from laser into soft x rays is about 80% according to the two-dimensional numerical simulation.
L. Batchelor
As reported in the April 2005 issue of the ATLAS eNews, the first of the four Semiconductor Tracker (SCT) barrels, complete with modules and services, arrived safely at CERN in January of 2005. In the months since January, the other three completed barrels arrived as well, and integration of the four barrels into the entire barrel assembly commenced at CERN, in the SR1 building on the ATLAS experimental site, in July. Assembly was completed on schedule in September, with the addition of the innermost layer to the 4-barrel assembly. Work is now underway to seal the barrel thermal enclosure. This is necessary in order to enclose the silicon tracker in a nitrogen atmosphere and provide it with faraday-cage protection, and is a delicate and complicated task: 352 silicon module powertapes, 352 readout-fibre bundles, and over 400 Detector Control System sensors must be carefully sealed into the thermal enclosure bulkhead. The team is currently verifying the integrity of the low mass cooling system, which must be d...
Validity of spherical quantitative refractometry: application to laser-produced plasmas
International Nuclear Information System (INIS)
Benattar, R.; Popovics, C.
1983-01-01
We report an experimental laser technique of quantitative Schlieren imaging of spherical plasmas combined with streak camera recording. We show that quantitative refractometry applies for small values of refraction angles, i.e., when the law giving the refraction angle versus the impact parameter of rays passing through the plasma is a linearly decreasing function
Quality control of radiosurgery: dosimetry with micro camera in spherical mannequin
International Nuclear Information System (INIS)
Casado Villalon, F. J.; Navarro Guirado, F.; Garci Pareja, S.; Benitez Villegas, E. M.; Galan Montenegro, P.; Moreno Saiz, C.
2013-01-01
The dosimetry of small field is part of quality control in the treatment of cranial radiosurgery. In this work the results of absorbed dose in the isocenter, Planner, with those obtained from are compared experimentally with a micro-camera into an spherical mannequin. (Author)
Calculation of spherical models of lead with a source of 14 MeV-neutrons
International Nuclear Information System (INIS)
Markovskij, D.V.; Borisov, A.A.
1989-01-01
Neutron transport calculations for spherical models of lead have been done with the one-dimensional code BLANK realizing the direct Monte Carlo method in the whole range of neutron energies and they are compared with the experimental results. 6 refs, 10 figs, 3 tabs
Fuzzy-based multi-kernel spherical support vector machine for ...
Indian Academy of Sciences (India)
In the proposed classifier, we design a new multi-kernel function based on the fuzzy triangular membership function. Finally, a newly developed multi-kernel function is incorporated into the spherical support vector machine to enhance the performance significantly. The experimental results are evaluated and performance is ...
Numerical analysis of laminar forced convection in a spherical annulus
International Nuclear Information System (INIS)
Tuft, D.B.
1980-01-01
Calculations of steady laminar incompressible fluid-flow and heat transfer in a spherical annulus are presented. Steady pressures, temperatures, velocities, and heat transfer coefficients are calculated for an insulated outer sphere and a 0 0 C isothermal inner sphere with 50 0 C heated water flowing in the annulus. The inner sphere radius is 13.97 cm, the outer sphere radius is 16.83 cm and the radius ratio is 1.2. The transient axisymmetric equations of heat, mass, and momentum conservation are solved numerically in spherical coordinates. The transient solution is carried out in time until steady state is achieved. A variable mesh is used to improve resolution near the inner sphere where temperature and velocity gradients are steep. It is believed that this is the first fully two-dimensional analysis of forced flow in a spherical annulus. Local and bulk Nusselt numbers are presented for Reynolds numbers from 4.4 to 440. Computed bulk Nusselt numbers ranged from 2 to 50 and are compared to experimental results from the literature. Inlet flow jetting off the inner sphere and flow separation are predicted by the analysis. The location of wall jet separation was found to be a function of Reynolds number, indicating the location of separation depends upon the ratio of inertia to viscous forces. Wall jet separation has a pronounced effect on the distribution of local heat flux. The area between inlet and separation was found to be the most significant area for heat transfer. Radial distributions of azimuthal velocity and temperature are presented for various angles beginning at the inlet. Inner sphere pressure distribution is presented and the effect on flow separation is discussed
Nuclear reactor fuel element sub-assemblies
International Nuclear Information System (INIS)
Hill, G.D.; Trevalion, P.A.
1977-01-01
A fuel element sub-assembly for a liquid metal cooled fast reactor is described. It comprises a bundle of fuel pins enclosed by a tubular wrapper having a lower end journal for plugging into an upper aperture in a core supporting structure and a spike bar with an articulated bush for engaging a lower aperture in the core supporting structure. The articulated bush is retained on a spherical end portion of the spike bar by a pair of parallel retaining pins arranged transversely and disposed one each side of the spike bar. The pins are tubular and collapsible at a predetermined loading to enable the spherical end portion to pass between them. The articulated bush has an internal groove for engagement by a lifting grab, this groove being formed in a bore for receiving the spherical end portion of the spike bar. The construction lessens liability to rattling of the fuel element sub-assemblies and aids removal for replacement. (U.K.)
Spherical Bessel transform via exponential sum approximation of spherical Bessel function
Ikeno, Hidekazu
2018-02-01
A new algorithm for numerical evaluation of spherical Bessel transform is proposed in this paper. In this method, the spherical Bessel function is approximately represented as an exponential sum with complex parameters. This is obtained by expressing an integral representation of spherical Bessel function in complex plane, and discretizing contour integrals along steepest descent paths and a contour path parallel to real axis using numerical quadrature rule with the double-exponential transformation. The number of terms in the expression is reduced using the modified balanced truncation method. The residual part of integrand is also expanded by exponential functions using Prony-like method. The spherical Bessel transform can be evaluated analytically on arbitrary points in half-open interval.
Sum frequency generation image reconstruction: Aliphatic membrane under spherical cap geometry
Energy Technology Data Exchange (ETDEWEB)
Volkov, Victor [Bereozovaya 2A, Konstantinovo, Moscow Region 140207 (Russian Federation)
2014-10-07
The article explores an opportunity to approach structural properties of phospholipid membranes using Sum Frequency Generation microscopy. To establish the principles of sum frequency generation image reconstruction in such systems, at first approach, we may adopt an idealistic spherical cap uniform assembly of hydrocarbon molecules. Quantum mechanical studies for decanoic acid (used here as a representative molecular system) provide necessary information on transition dipole moments and Raman tensors of the normal modes specific to methyl terminal – a typical moiety in aliphatic (and phospholipid) membranes. Relative degree of localization and frequencies of the normal modes of methyl terminals make nonlinearities of this moiety to be promising in structural analysis using Sum Frequency Generation imaging. Accordingly, the article describes derivations of relevant macroscopic nonlinearities and suggests a mapping procedure to translate amplitudes of the nonlinearities onto microscopy image plane according to geometry of spherical assembly, local molecular orientation, and optical geometry. Reconstructed images indicate a possibility to extract local curvature of bilayer envelopes of spherical character. This may have practical implications for structural extractions in membrane systems of practical relevance.
Directory of Open Access Journals (Sweden)
Yali Lin
2017-11-01
Full Text Available Cholesteric liquid crystals (CLCs exhibit selective Bragg reflections of circularly polarized (CP light owing to their spontaneous self-assembly abilities into periodic helical structures. Photonic cross-communication patterns could be generated toward potential security applications by spherical cholesteric liquid crystal (CLC structures. To endow these optical patterns with tunability, we fabricated spherical CLC Bragg reflectors in the shape of microshells by glass-capillary microfluidics. Water-soluble magnetofluid with Fe3O4 nanoparticles incorporated in the inner aqueous core of CLC shells is responsible for the non-invasive transportable capability. With the aid of an external magnetic field, the reflection interactions between neighboring microshells and microdroplets were identified by varying the mutual distance in a group of magnetically transportable and unmovable spherical CLC structures. The temperature-dependent optical reflection patterns were investigated in close-packed hexagonal arrangements of seven CLC microdroplets and microshells with inverse helicity handedness. Moreover, we demonstrated that the magnetic field-assisted assembly of microshells array into geometric figures of uppercase English letters “L” and “C” was successfully achieved. We hope that these findings can provide good application prospects for security pattern designs.
Lin, Yali; Yang, Yujie; Shan, Yuwei; Gong, Lingli; Chen, Jingzhi; Li, Sensen; Chen, Lujian
2017-11-08
Cholesteric liquid crystals (CLCs) exhibit selective Bragg reflections of circularly polarized (CP) light owing to their spontaneous self-assembly abilities into periodic helical structures. Photonic cross-communication patterns could be generated toward potential security applications by spherical cholesteric liquid crystal (CLC) structures. To endow these optical patterns with tunability, we fabricated spherical CLC Bragg reflectors in the shape of microshells by glass-capillary microfluidics. Water-soluble magnetofluid with Fe₃O₄ nanoparticles incorporated in the inner aqueous core of CLC shells is responsible for the non-invasive transportable capability. With the aid of an external magnetic field, the reflection interactions between neighboring microshells and microdroplets were identified by varying the mutual distance in a group of magnetically transportable and unmovable spherical CLC structures. The temperature-dependent optical reflection patterns were investigated in close-packed hexagonal arrangements of seven CLC microdroplets and microshells with inverse helicity handedness. Moreover, we demonstrated that the magnetic field-assisted assembly of microshells array into geometric figures of uppercase English letters "L" and "C" was successfully achieved. We hope that these findings can provide good application prospects for security pattern designs.
Stochastic modeling of virus capsid assembly pathways
Schwartz, Russell
2009-03-01
Virus capsids have become a key model system for understanding self-assembly due to their high complexity, robust and efficient assembly processes, and experimental tractability. Our ability to directly examine and manipulate capsid assembly kinetics in detail nonetheless remains limited, creating a need for computer models that can infer experimentally inaccessible features of the assembly process and explore the effects of hypothetical manipulations on assembly trajectories. We have developed novel algorithms for stochastic simulation of capsid assembly [1,2] that allow us to model capsid assembly over broad parameter spaces [3]. We apply these methods to study the nature of assembly pathway control in virus capsids as well as their sensitivity to assembly conditions and possible experimental interventions. [4pt] [1] F. Jamalyaria, R. Rohlfs, and R. Schwartz. J Comp Phys 204, 100 (2005). [0pt] [2] N. Misra and R. Schwartz. J Chem Phys 129, in press (2008). [0pt] [3] B. Sweeney, T. Zhang, and R. Schwartz. Biophys J 94, 772 (2008).
Flow resistance in rod assemblies
International Nuclear Information System (INIS)
Korsun, A.S.; Sokolova, M.S.
2000-01-01
The general form of relation between the resistance force and the velocity vector, resistance tensor structure and possible types of anisotropy in the flow thorough such structures as rod or tube assemblies are under discussion. Some questions of experimental determination of volumetric resistance force tensor are also under consideration. (author)
International Nuclear Information System (INIS)
Hirukawa, Koji; Sakurada, Koichi.
1992-01-01
In a fuel assembly for a BWR type reactor, water rods or water crosses are disposed between fuel rods, and a value with a spring is disposed at the top of the coolant flow channel thereof, which opens a discharge port when pressure is increased to greater than a predetermined value. Further, a control element for the amount of coolant flow rate is inserted retractable to a control element guide tube formed at the lower portion of the water rod or the water cross. When the amount of control elements inserted to the control element guide tube is small and the inflown coolant flow rate is great, the void coefficient at the inside of the water rod is less than 5%. On the other hand, when the control elements are inserted, the flow resistance is increased, so that the void coefficient in the water rod is greater than 80%. When the pressure in the water rod is increased, the valve with the spring is raised to escape water or steams. Then, since the variation range of the change of the void coefficient can be controlled reliably by the amount of the control elements inserted, and nuclear fuel materials can be utilized effectively. (N.H.)
International Nuclear Information System (INIS)
Hiraiwa, Koji; Ueda, Makoto
1989-01-01
In a fuel assembly used for a light water cooled reactor such as a BWR type reactor, a water rod is divided axially into an upper outer tube and a lower outer tube by means of a plug disposed from the lower end of a water rod to a position 1/4 - 1/2 of the entire length for the water rod. Inlet apertures and exit apertures for moderators are respectively perforated for the divided outer tube and upper and lower portions. Further, an upper inner tube with less neutron irradiation growing amount than the outer tube is perforated on the plug in the outer tube, while a lower inner tube with greater neutron irradiation growing amount than the outer tube is suspended from the lower surface of the plug in the outer tube. Then, the opening area for the exit apertures disposed to the upper outer tube and the lower outer tube is controlled depending on the difference of the neutron irradiation growing amount between the upper inner tube and the upper outer tube, and the difference of the neutron irradiation growing amount between the lower inner tube and the lower outer tube. This enables effective spectral shift operation and improve the fuel economy. (T.M.)
International Nuclear Information System (INIS)
Yamazaki, Hajime.
1995-01-01
In a fuel assembly having fuel rods of different length, fuel pellets of mixed oxides of uranium and plutonium are loaded to a short fuel rod. The volume ratio of a pellet-loaded portion to a plenum portion of the short fuel rod is made greater than the volume ratio of a fuel rod to which uranium fuel pellets are loaded. In addition, the volume of the plenum portion of the short fuel rod is set greater depending on the plutonium content in the loaded fuel pellets. MOX fuel pellets are loaded on the short fuel rods having a greater degree of freedom relevant to the setting for the volume of the plenum portion compared with that of a long rod fuel, and the volume of the plenum portion is ensured greater depending on the plutonium content. Even if a large amount of FP gas and He gas are discharged from the MOX fuels compared with that from the uranium fuels, the internal pressure of the MOX fuel rod during operation is maintained substantially identical with that of the uranium fuel rod, so that a risk of generating excess stresses applied to the fuel cladding tubes and rupture of fuels are greatly reduced. (N.H.)
International Nuclear Information System (INIS)
Nakajima, Akiyoshi; Bessho, Yasunori; Aoyama, Motoo; Koyama, Jun-ichi; Hirakawa, Hiromasa; Yamashita, Jun-ichi; Hayashi, Tatsuo
1998-01-01
In a fuel assembly of a BWR type reactor in which a water rod of a large diameter is disposed at the central portion, the cross sectional area perpendicular to the axial direction comprises a region a of a fuel rod group facing to a wide gap water region to which a control rod is inserted, a region b of a fuel rod group disposed on the side of the wide gap water region other than the region a, a region d of a fuel rod group facing to a narrow gap water region and a region c of a fuel rod group disposed on the side of the narrow gap water region other than the region d. When comparing an amount of fission products contained in the four regions relative to that in the entire regions and average enrichment degrees of fuel rods for the four regions, the relative amount and the average enrichment degree of the fuel rod group of the region a is minimized, and the relative amount and the average enrichment degree of the fuel rod group in the region b is maximized. Then, reactor shut down margin during cold operation can be improved while flattening the power in the cross section perpendicular to the axial direction. (N.H.)
Energy Technology Data Exchange (ETDEWEB)
Murata, Isao [Osaka Univ., Suita (Japan); Mori, Takamasa; Nakagawa, Masayuki; Itakura, Hirofumi
1996-03-01
The method to calculate neutronics parameters of a core composed of randomly distributed spherical fuels has been developed based on a statistical geometry model with a continuous energy Monte Carlo method. This method was implemented in a general purpose Monte Carlo code MCNP, and a new code MCNP-CFP had been developed. This paper describes the model and method how to use it and the validation results. In the Monte Carlo calculation, the location of a spherical fuel is sampled probabilistically along the particle flight path from the spatial probability distribution of spherical fuels, called nearest neighbor distribution (NND). This sampling method was validated through the following two comparisons: (1) Calculations of inventory of coated fuel particles (CFPs) in a fuel compact by both track length estimator and direct evaluation method, and (2) Criticality calculations for ordered packed geometries. This method was also confined by applying to an analysis of the critical assembly experiment at VHTRC. The method established in the present study is quite unique so as to a probabilistic model of the geometry with a great number of spherical fuels distributed randomly. Realizing the speed-up by vector or parallel computations in future, it is expected to be widely used in calculation of a nuclear reactor core, especially HTGR cores. (author).
Xu, Sheng; Yan, Zheng; Jang, Kyung-In; Huang, Wen; Fu, Haoran; Kim, Jeonghyun; Wei, Zijun; Flavin, Matthew; McCracken, Joselle; Wang, Renhan; Badea, Adina; Liu, Yuhao; Xiao, Dongqing; Zhou, Guoyan; Lee, Jungwoo; Chung, Ha Uk; Cheng, Huanyu; Ren, Wen; Banks, Anthony; Li, Xiuling; Paik, Ungyu; Nuzzo, Ralph G; Huang, Yonggang; Zhang, Yihui; Rogers, John A
2015-01-09
Complex three-dimensional (3D) structures in biology (e.g., cytoskeletal webs, neural circuits, and vasculature networks) form naturally to provide essential functions in even the most basic forms of life. Compelling opportunities exist for analogous 3D architectures in human-made devices, but design options are constrained by existing capabilities in materials growth and assembly. We report routes to previously inaccessible classes of 3D constructs in advanced materials, including device-grade silicon. The schemes involve geometric transformation of 2D micro/nanostructures into extended 3D layouts by compressive buckling. Demonstrations include experimental and theoretical studies of more than 40 representative geometries, from single and multiple helices, toroids, and conical spirals to structures that resemble spherical baskets, cuboid cages, starbursts, flowers, scaffolds, fences, and frameworks, each with single- and/or multiple-level configurations. Copyright © 2015, American Association for the Advancement of Science.
A simple method to measure the trajectory of a spherical pendulum
Energy Technology Data Exchange (ETDEWEB)
Yang Hujiang; Xiao Jinghua; Yang Tianyu; Qiu Chen, E-mail: jhxiao@bupt.edu.cn [School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China)
2011-07-15
Compared with a single gravity pendulum, the spherical pendulum behaves more complicatedly in experiments, which makes it difficult to measure. In this paper, we present a method to visualize the trajectories of a spherical pendulum by employing a gravity ball with a lit LED and a digital camera. This new measurement is inexpensive and easy to use. We analyse the experimental results with the help of analytical mechanics, and give the numerical simulation for better understanding. The experiment is carried out in our physics undergraduate laboratory. Through the experiment, we can improve students' existing knowledge and evoke their creativity.
Hematite Thin Films with Various Nanoscopic Morphologies Through Control of Self-Assembly Structures
Liu, Jingling; Kim, Yong-Tae; Kwon, Young-Uk
2015-05-01
Hematite (α-Fe2O3) thin films with various nanostructures were synthesized through self-assembly between iron oxide hydroxide particles, generated by hydrolysis and condensation of Fe(NO3)3 · 6H2O, and a Pluronic triblock copolymer (F127, (EO)106(PO)70(EO)106, EO = ethylene oxide, PO = propylene oxide), followed by calcination. The self-assembly structure can be tuned by introducing water in a controlled manner through the control of the humidity level in the surrounding of the as-cast films during aging stage. For the given Fe(NO3)3 · 6H2O:F127 ratio, there appear to be three different thermodynamically stable self-assembly structures depending on the water content in the film material, which correspond to mesoporous, spherical micellar, and rod-like micellar structures after removal of F127. Coupled with the thermodynamic driving forces, the kinetics of the irreversible reactions of coalescence of iron oxide hydroxide particles into larger ones induce diverse nanostructures of the resultant films. The length scale of so-obtained nanostructures ranges from 6 nm to a few hundred nanometers. In addition to water content, the effects of other experimental parameters such as aging temperature, spin rate during spin coating, type of substrate, and type of iron reagent were investigated.
A multi purpose 4 π counter spherical ionization chamber type
International Nuclear Information System (INIS)
Calin, Marian Romeo; Calin, Adrian Cantemir
2004-01-01
A pressurized ionization chamber detector able to measure radioactive sources in internal 2π or 4π geometry was built in order to characterize alpha and beta radioactive sources, i.e. to calibrate these sources by relative method and to test the behavior of gas mixtures in pressurized-gas radiation detectors. The detector we made is of spherical shape and works by collecting in a uniform electric field the ionization charges resulting from the interaction of ionizing radiation with gas in the sensitive volume of the chamber. An ionizing current proportional to the activity of the radioactive source to be measured is obtained. In this paper a gas counter with a spherical symmetry is described. This detector can work in a very satisfactory manner, either as a flow counter or as a ionization chamber reaching in the latter case a good α pulse height resolution, even with large emitting sources. Calculations are made in order to find the dependence of the pulse shape on the direction of emission of an α-particle by a point source in the chamber (finite track). A good agreement is found between these calculations and the experimental tests performed, which show that this dependence can be employed in high efficiency measurements of angular α-γ correlations. (authors)
Non-conformal contact mechanical characteristic analysis on spherical components
Energy Technology Data Exchange (ETDEWEB)
Zhen-zhi, G.; Bin, H.; Zheng-ming, G.; Feng-mei, Y.; Jin, Q [The 2. Artillery Engineering Univ., Xi' an (China)
2017-03-15
Non-conformal spherical-contact mechanical problems is a three-dimensional coordination or similar to the coordination spherical contact. Due to the complexity of the problem of spherical-contact and difficulties of solving higher-order partial differential equations, problems of three-dimensional coordination or similar to the coordination spherical-contact is still no exact analytical method for solving. It is based on three-dimensional taper model is proposed a model based on the contour surface of the spherical contact and concluded of the formula of the contact pressure and constructed of finite element model by contact pressure distribution under the non-conformal spherical. The results shows spherical contact model can reflect non-conformal spherical-contacting mechanical problems more than taper-contacting model, and apply for the actual project.
Normal modes and quality factors of spherical dielectric resonators: I ...
Indian Academy of Sciences (India)
Eigenmodes; spherical resonators; spherical dielectric resonators; quality factors. PACS No. 42.50. .... Alternatively, introducing the angular momentum operator L defined as, L = (1/j)( r × ∇) ...... referee of the article for some helpful comments.
Agnolin, Ivana; Roux, Jean-Noël
2007-12-01
This is the first paper of a series of three, in which we report on numerical simulation studies of geometric and mechanical properties of static assemblies of spherical beads under an isotropic pressure. The influence of various assembling processes on packing microstructures is investigated. It is accurately checked that frictionless systems assemble in the unique random close packing (RCP) state in the low pressure limit if the compression process is fast enough, higher solid fractions corresponding to more ordered configurations with traces of crystallization. Specific properties directly related to isostaticity of the force-carrying structure in the rigid limit are discussed. With frictional grains, different preparation procedures result in quite different inner structures that cannot be classified by the sole density. If partly or completely lubricated they will assemble like frictionless ones, approaching the RCP solid fraction Phi_{RCP} approximately 0.639 with a high coordination number: z* approximately =6 on the force-carrying backbone. If compressed with a realistic coefficient of friction mu=0.3 packings stabilize in a loose state with Phi approximately 0.593 and z* approximately =4.5 . And, more surprisingly, an idealized "vibration" procedure, which maintains an agitated, collisional regime up to high densities results in equally small values of z* while Phi is close to the maximum value Phi_{RCP}. Low coordination packings have a large proportion (>10%) of rattlers--grains carrying no force--the effect of which should be accounted for on studying position correlations, and also contain a small proportion of localized "floppy modes" associated with divalent grains. Low-pressure states of frictional packings retain a finite level of force indeterminacy even when assembled with the slowest compression rates simulated, except in the case when the friction coefficient tends to infinity. Different microstructures are characterized in terms of near
Quality metric for spherical panoramic video
Zakharchenko, Vladyslav; Choi, Kwang Pyo; Park, Jeong Hoon
2016-09-01
Virtual reality (VR)/ augmented reality (AR) applications allow users to view artificial content of a surrounding space simulating presence effect with a help of special applications or devices. Synthetic contents production is well known process form computer graphics domain and pipeline has been already fixed in the industry. However emerging multimedia formats for immersive entertainment applications such as free-viewpoint television (FTV) or spherical panoramic video require different approaches in content management and quality assessment. The international standardization on FTV has been promoted by MPEG. This paper is dedicated to discussion of immersive media distribution format and quality estimation process. Accuracy and reliability of the proposed objective quality estimation method had been verified with spherical panoramic images demonstrating good correlation results with subjective quality estimation held by a group of experts.
Simplified discrete ordinates method in spherical geometry
International Nuclear Information System (INIS)
Elsawi, M.A.; Abdurrahman, N.M.; Yavuz, M.
1999-01-01
The authors extend the method of simplified discrete ordinates (SS N ) to spherical geometry. The motivation for such an extension is that the appearance of the angular derivative (redistribution) term in the spherical geometry transport equation makes it difficult to decide which differencing scheme best approximates this term. In the present method, the angular derivative term is treated implicitly and thus avoids the need for the approximation of such term. This method can be considered to be analytic in nature with the advantage of being free from spatial truncation errors from which most of the existing transport codes suffer. In addition, it treats the angular redistribution term implicitly with the advantage of avoiding approximations to that term. The method also can handle scattering in a very general manner with the advantage of spending almost the same computational effort for all scattering modes. Moreover, the methods can easily be applied to higher-order S N calculations
Spherical harmonics and integration in superspace
International Nuclear Information System (INIS)
Bie, H de; Sommen, F
2007-01-01
In this paper, the classical theory of spherical harmonics in R m is extended to superspace using techniques from Clifford analysis. After defining a super-Laplace operator and studying some basic properties of polynomial null-solutions of this operator, a new type of integration over the supersphere is introduced by exploiting the formal equivalence with an old result of Pizzetti. This integral is then used to prove orthogonality of spherical harmonics of different degree, Green-like theorems and also an extension of the important Funk-Hecke theorem to superspace. Finally, this integration over the supersphere is used to define an integral over the whole superspace, and it is proven that this is equivalent with the Berezin integral, thus providing a more sound definition of the Berezin integral
Spherical projections and liftings in geometric tomography
DEFF Research Database (Denmark)
Goodey, Paul; Kiderlen, Markus; Weil, Wolfgang
2011-01-01
We consider a variety of integral transforms arising in Geometric Tomography. It will be shown that these can be put into a common framework using spherical projection and lifting operators. These operators will be applied to support functions and surface area measures of convex bodies and to rad......We consider a variety of integral transforms arising in Geometric Tomography. It will be shown that these can be put into a common framework using spherical projection and lifting operators. These operators will be applied to support functions and surface area measures of convex bodies...... and to radial functions of star bodies. We then investigate averages of lifted projections and show that they correspond to self-adjoint intertwining operators. We obtain formulas for the eigenvalues of these operators and use them to ascertain circumstances under which tomographic measurements determine...... the original bodies. This approach via mean lifted projections leads us to some unexpected relationships between seemingly disparate geometric constructions....
Benchmark assemblies of the Los Alamos Critical Assemblies Facility
International Nuclear Information System (INIS)
Dowdy, E.J.
1985-01-01
Several critical assemblies of precisely known materials composition and easily calculated and reproducible geometries have been constructed at the Los Alamos National Laboratory. Some of these machines, notably Jezebel, Flattop, Big Ten, and Godiva, have been used as benchmark assemblies for the comparison of the results of experimental measurements and computation of certain nuclear reaction parameters. These experiments are used to validate both the input nuclear data and the computational methods. The machines and the applications of these machines for integral nuclear data checks are described
Benchmark assemblies of the Los Alamos critical assemblies facility
International Nuclear Information System (INIS)
Dowdy, E.J.
1986-01-01
Several critical assemblies of precisely known materials composition and easily calculated and reproducible geometries have been constructed at the Los Alamos National Laboratory. Some of these machines, notably Jezebel, Flattop, Big Ten, and Godiva, have been used as benchmark assemblies for the comparison of the results of experimental measurements and computation of certain nuclear reaction parameters. These experiments are used to validate both the input nuclear data and the computational methods. The machines and the applications of these machines for integral nuclear data checks are described. (author)
Benchmark assemblies of the Los Alamos critical assemblies facility
International Nuclear Information System (INIS)
Dowdy, E.J.
1985-01-01
Several critical assemblies of precisely known materials composition and easily calculated and reproducible geometries have been constructed at the Los Alamos National Laboratory. Some of these machines, notably Jezebel, Flattop, Big Ten, and Godiva, have been used as benchmark assemblies for the comparison of the results of experimental measurements and computation of certain nuclear reaction parameters. These experiments are used to validate both the input nuclear data and the computational methods. The machines and the applications of these machines for integral nuclear data checks are described
Spherical Cancer Models in Tumor Biology
Directory of Open Access Journals (Sweden)
Louis-Bastien Weiswald
2015-01-01
Full Text Available Three-dimensional (3D in vitro models have been used in cancer research as an intermediate model between in vitro cancer cell line cultures and in vivo tumor. Spherical cancer models represent major 3D in vitro models that have been described over the past 4 decades. These models have gained popularity in cancer stem cell research using tumorospheres. Thus, it is crucial to define and clarify the different spherical cancer models thus far described. Here, we focus on in vitro multicellular spheres used in cancer research. All these spherelike structures are characterized by their well-rounded shape, the presence of cancer cells, and their capacity to be maintained as free-floating cultures. We propose a rational classification of the four most commonly used spherical cancer models in cancer research based on culture methods for obtaining them and on subsequent differences in sphere biology: the multicellular tumor spheroid model, first described in the early 70s and obtained by culture of cancer cell lines under nonadherent conditions; tumorospheres, a model of cancer stem cell expansion established in a serum-free medium supplemented with growth factors; tissue-derived tumor spheres and organotypic multicellular spheroids, obtained by tumor tissue mechanical dissociation and cutting. In addition, we describe their applications to and interest in cancer research; in particular, we describe their contribution to chemoresistance, radioresistance, tumorigenicity, and invasion and migration studies. Although these models share a common 3D conformation, each displays its own intrinsic properties. Therefore, the most relevant spherical cancer model must be carefully selected, as a function of the study aim and cancer type.
Fusion technology applications of the spherical tokamak
International Nuclear Information System (INIS)
Robinson, D.C.; Akers, R.; Allfrey, S.J.
1999-01-01
Fusion technology applications of the spherical tokamak are presented, exploiting its high β capability, normal conducting TF coils, compact core, high natural elongation, disruption resilience and low capital cost. We concentrate here on two particular applications: a volume neutron source (VNS) for component testing and a power plant, addressing engineering and physics issues for steady state operation. The prospect of nearer term burning plasma ST devices are discussed in the conclusions. (author)
Fusion technology applications of the spherical tokamak
International Nuclear Information System (INIS)
Robinson, D.C.; Akers, R.; Allfrey, S.J.
2001-01-01
Fusion technology applications of the spherical tokamak are presented, exploiting its high β capability, normal conducting TF coils, compact core, high natural elongation, disruption resilience and low capital cost. We concentrate here on two particular applications: a volume neutron source (VNS) for component testing and a power plant, addressing engineering and physics issues for steady state operation. The prospect of nearer term burning plasma ST devices are discussed in the conclusions. (author)
Particles in spherical electromagnetic radiation fields
International Nuclear Information System (INIS)
Mitter, H.; Thaller, B.
1984-03-01
If the time-dependence of a Hamiltonian can be compensated by an appropriate symmetry transformation, the corresponding quantum mechanical problem can be reduced to an effectively stationary one. With this result we investigate the behavior of nonrelativistic particles in a spherical radiation field produced by a rotating source. Then the symmetry transformation corresponds to a rotation. We calculate the transition probabilities in Born approximation. The extension to problems involving an additional Coulomb potential is briefly discussed. (Author)
New mathematical framework for spherical gravitational collapse
International Nuclear Information System (INIS)
Giambo, Roberto; Giannoni, Fabio; Magli, Giulio; Piccione, Paolo
2003-01-01
A theorem, giving necessary and sufficient condition for naked singularity formation in spherically symmetric non-static spacetimes under hypotheses of physical acceptability, is formulated and proved. The theorem relates the existence of singular null geodesics to the existence of regular curves which are supersolutions of the radial null geodesic equation, and allows us to treat all the known examples of naked singularities from a unified viewpoint. New examples are also found using this approach, and perspectives are discussed. (letter to the editor)
Spherical tokamak without external toroidal fields
International Nuclear Information System (INIS)
Kaw, P.K.; Avinash, K.; Srinivasan, R.
2001-01-01
A spherical tokamak design without external toroidal field coils is proposed. The tokamak is surrounded by a spheromak shell carrying requisite force free currents to produce the toroidal field in the core. Such equilibria are constructed and it is indicated that these equilibria are likely to have robust ideal and resistive stability. The advantage of this scheme in terms of a reduced ohmic dissipation is pointed out. (author)
Sub-critical pulsed neutron experiments with uranyl nitrate solutions in spherical geometry
International Nuclear Information System (INIS)
Gurin, Victor N.; Ryazanov, Boris G.; Sviridov, Victor I.; Volnistov, Vladimir V.
2003-01-01
The pulse source method is used to study homogeneous solution assemblies. Three sets of sub-critical pulse experiments with spherical tanks filled with water solution of uranyl nitrate (90% enrichment) were carried out at the RF-GS facility, Obninsk, Russia. Seven spherical tanks with the volume within the range of 1.29 L to 19.8 L were used in the experiments. Three uranium concentrations were studied, i.e. 20.7, 29.6 and 37.5 g/L. The sub-critical experiments were analyzed with the MCNP 4A code based on the Monte-Carlo method, and with ENDF/B-V library. (author)
Reverse depletion effects and the determination of ligand density on some spherical bioparticles
Energy Technology Data Exchange (ETDEWEB)
Wang, Chunxiang [Heilongjiang Bayi Agricultural University (China); Liu, Yanhui, E-mail: ionazati@itp.ac.cn; Fan, Yangtao; Liu, Yijun; Li, Qiancheng; Xu, Houqiang, E-mail: houqiangxu@yahoo.com [Guizhou University (China)
2016-06-15
In cell environments crowded with macromolecules, the depletion effects act and assist in the assembly of a wide range of cellular structures, from the cytoskeleton to the chromatin loop, which are well accepted. But a recent quantum dot experiment indicated that the dimensions of the receptor–ligand complex have strong effects on the size-dependent exclusion of proteins in cell environments. In this article, a continuum elastic model is constructed to resolve the competition between the dimension of the receptor–ligand complex and depletion effects in the endocytosis of a spherical virus-like bioparticle. Our results show that the depletion effects do not always assist endocytosis of a spherical virus-like bioparticle; while the dimension of the ligand–receptor complex is larger than the size of a small bioparticle in cell environments, the depletion effects do not work and reverse effects appear. The ligand density covered on the virus can be identified quantitatively.
Indicators of Mass in Spherical Stellar Atmospheres
Lester, John B.; Dinshaw, Rayomond; Neilson, Hilding R.
2013-04-01
Mass is the most important stellar parameter, but it is not directly observable for a single star. Spherical model stellar atmospheres are explicitly characterized by their luminosity ( L⋆), mass ( M⋆), and radius ( R⋆), and observations can now determine directly L⋆ and R⋆. We computed spherical model atmospheres for red giants and for red supergiants holding L⋆ and R⋆ constant at characteristic values for each type of star but varying M⋆, and we searched the predicted flux spectra and surface-brightness distributions for features that changed with mass. For both stellar classes we found similar signatures of the stars’ mass in both the surface-brightness distribution and the flux spectrum. The spectral features have been use previously to determine log 10(g), and now that the luminosity and radius of a non-binary red giant or red supergiant can be observed, spherical model stellar atmospheres can be used to determine a star’s mass from currently achievable spectroscopy. The surface-brightness variations of mass are slightly smaller than can be resolved by current stellar imaging, but they offer the advantage of being less sensitive to the detailed chemical composition of the atmosphere.
Fusion potential for spherical and compact tokamaks
International Nuclear Information System (INIS)
Sandzelius, Mikael
2003-02-01
The tokamak is the most successful fusion experiment today. Despite this, the conventional tokamak has a long way to go before being realized into an economically viable power plant. In this master thesis work, two alternative tokamak configurations to the conventional tokamak has been studied, both of which could be realized to a lower cost. The fusion potential of the spherical and the compact tokamak have been examined with a comparison of the conventional tokamak in mind. The difficulties arising in the two configurations have been treated from a physical point of view concerning the fusion plasma and from a technological standpoint evolving around design, materials and engineering. Both advantages and drawbacks of either configuration have been treated relative to the conventional tokamak. The spherical tokamak shows promising plasma characteristics, notably a high β-value but have troubles with high heat loads and marginal tritium breeding. The compact tokamak operates at a high plasma density and a high magnetic field enabling it to be built considerably smaller than any other tokamak. The most notable down-side being high heat loads and neutron transport problems. With the help of theoretical reactor studies, extrapolating from where we stand today, it is conceivable that the spherical tokamak is closer of being realized of the two. But, as this study shows, the compact tokamak power plant concept offers the most appealing prospect
Fusion potential for spherical and compact tokamaks
Energy Technology Data Exchange (ETDEWEB)
Sandzelius, Mikael
2003-02-01
The tokamak is the most successful fusion experiment today. Despite this, the conventional tokamak has a long way to go before being realized into an economically viable power plant. In this master thesis work, two alternative tokamak configurations to the conventional tokamak has been studied, both of which could be realized to a lower cost. The fusion potential of the spherical and the compact tokamak have been examined with a comparison of the conventional tokamak in mind. The difficulties arising in the two configurations have been treated from a physical point of view concerning the fusion plasma and from a technological standpoint evolving around design, materials and engineering. Both advantages and drawbacks of either configuration have been treated relative to the conventional tokamak. The spherical tokamak shows promising plasma characteristics, notably a high {beta}-value but have troubles with high heat loads and marginal tritium breeding. The compact tokamak operates at a high plasma density and a high magnetic field enabling it to be built considerably smaller than any other tokamak. The most notable down-side being high heat loads and neutron transport problems. With the help of theoretical reactor studies, extrapolating from where we stand today, it is conceivable that the spherical tokamak is closer of being realized of the two. But, as this study shows, the compact tokamak power plant concept offers the most appealing prospect.
Collisions of droplets on spherical particles
Charalampous, Georgios; Hardalupas, Yannis
2017-10-01
Head-on collisions between droplets and spherical particles are examined for water droplets in the diameter range between 170 μm and 280 μm and spherical particles in the diameter range between 500 μm and 2000 μm. The droplet velocities range between 6 m/s and 11 m/s, while the spherical particles are fixed in space. The Weber and Ohnesorge numbers and ratio of droplet to particle diameter were between 92 deposition and splashing regimes, a regime is observed in the intermediate region, where the droplet forms a stable crown, which does not breakup but propagates along the particle surface and passes around the particle. This regime is prevalent when the droplets collide on small particles. The characteristics of the collision at the onset of rim instability are also described in terms of the location of the film on the particle surface and the orientation and length of the ejected crown. Proper orthogonal decomposition identified that the first 2 modes are enough to capture the overall morphology of the crown at the splashing threshold.
Next Step Spherical Torus Design Studies
International Nuclear Information System (INIS)
Neumeyer, C.; Heitzenroeder, P.; Kessel, C.; Ono, M.; Peng, M.; Schmidt, J.; Woolley, R.; Zatz, I.
2002-01-01
Studies are underway to identify and characterize a design point for a Next Step Spherical Torus (NSST) experiment. This would be a ''Proof of Performance'' device which would follow and build upon the successes of the National Spherical Torus Experiment (NSTX) a ''Proof of Principle'' device which has operated at PPPL since 1999. With the Decontamination and Decommissioning (DandD) of the Tokamak Fusion Test Reactor (TFTR) nearly completed, the TFTR test cell and facility will soon be available for a device such as NSST. By utilizing the TFTR test cell, NSST can be constructed for a relatively low cost on a short time scale. In addition, while furthering spherical torus (ST) research, this device could achieve modest fusion power gain for short-pulse lengths, a significant step toward future large burning plasma devices now under discussion in the fusion community. The selected design point is Q=2 at HH=1.4, P subscript ''fusion''=60 MW, 5 second pulse, with R subscript ''0''=1.5 m, A=1.6, I subscript ''p''=10vMA, B subscript ''t''=2.6 T, CS flux=16 weber. Most of the research would be conducted in D-D, with a limited D-T campaign during the last years of the program
Integrals of products of spherical functions
International Nuclear Information System (INIS)
Veverka, O.
1975-01-01
Various branches of mathematical physics use integral formulas of the products of spherical functions. In quantum mechanics and in transport theory the integrals ∫sub((4π))dΩ vectorYsub(s)sup(t)(Ω vector)Ysub(l)sup(k)(Ω vector)Ysub(n)sup(m)(Ω vector), ∫sub(-1)sup(1)dμPsub(s)sup(t)(μ)Psub(l)sup(k)(μ)Psub(n)sup(m)(μ), ∫sub(-1)sup(1)dμPsub(s)(μ)Psub(l)(μ)Psub(n)(μ) are generally applied, where Ysub(α)sup(β)(Ω vector) are spherical harmonics, Psub(α)sup(β)(μ) are associated Legendre functions, and Psub(α)(μ) are Legendre polynomials. In the paper, the general procedure of calculating the integrals of the products of any combination of spherical functions is given. The procedure is referred to in a report on the boundary conditions for the cylindrical geometry in neutron transport theory for both the outer and inner cylindrical boundaries. (author)
High-Accuracy Spherical Near-Field Measurements for Satellite Antenna Testing
DEFF Research Database (Denmark)
Breinbjerg, Olav
2017-01-01
The spherical near-field antenna measurement technique is unique in combining several distinct advantages and it generally constitutes the most accurate technique for experimental characterization of radiation from antennas. From the outset in 1970, spherical near-field antenna measurements have...... matured into a well-established technique that is widely used for testing antennas for many wireless applications. In particular, for high-accuracy applications, such as remote sensing satellite missions in ESA's Earth Observation Programme with uncertainty requirements at the level of 0.05dB - 0.10d......B, the spherical near-field antenna measurement technique is generally superior. This paper addresses the means to achieving high measurement accuracy; these include the measurement technique per se, its implementation in terms of proper measurement procedures, the use of uncertainty estimates, as well as facility...
Shi, Zhaoyao; Song, Huixu; Chen, Hongfang; Sun, Yanqiang
2018-02-01
This paper presents a novel experimental approach for confirming that spherical mirror of a laser tracking system can reduce the influences of rotation errors of gimbal mount axes on the measurement accuracy. By simplifying the optical system model of laser tracking system based on spherical mirror, we can easily extract the laser ranging measurement error caused by rotation errors of gimbal mount axes with the positions of spherical mirror, biconvex lens, cat's eye reflector, and measuring beam. The motions of polarization beam splitter and biconvex lens along the optical axis and vertical direction of optical axis are driven by error motions of gimbal mount axes. In order to simplify the experimental process, the motion of biconvex lens is substituted by the motion of spherical mirror according to the principle of relative motion. The laser ranging measurement error caused by the rotation errors of gimbal mount axes could be recorded in the readings of laser interferometer. The experimental results showed that the laser ranging measurement error caused by rotation errors was less than 0.1 μm if radial error motion and axial error motion were within ±10 μm. The experimental method simplified the experimental procedure and the spherical mirror could reduce the influences of rotation errors of gimbal mount axes on the measurement accuracy of the laser tracking system.
Energy Technology Data Exchange (ETDEWEB)
Hansen, G E [Los Alamos Scientific Laboratory, University of California, Los Alamos, NM (United States)
1962-03-15
New assemblies and improved measuring techniques call for periodic review of the status of computation vs. experiment. It is appropriate to emphasize neutron-spectral characterizations because of the particularly elusive problems associated with absolute spectral-index measurement and the need for checks of computation beyond simple critical size. The ever-improving spectral-index measurements in conjunction with increasing precision, both of microscopic data for detector and assembly materials and of computational techniques, produce a gradual clarification of the characteristics of a family of fast-neutron critical assemblies. This family now includes unreflected and thick-uranium-reflected U{sup 233} in spherical geometry. Direct correlations among the experimental data will be presented to indicate the a priori possibilities for successful correlations with computation. Sensitivity of computed spectra and critical sizes to neutron-transport models (transport and linear approximations ) and arithmetic approximations (finite angular segmentations and multi-group representations) will be presented for several typical assemblies to help establish the necessary computational detail. Comparisons between experiment and prediction will include, in addition to spectral indices and critical sizes, neutron lifetimes and delayed-neutron fractions. (author) [French] Du fait de la mise en service de nouveaux reacteurs et de l'amelioration des methodes de mesure, il est necessaire de faire periodiquement la correlation des experiences et des calculs. Il est utile d'insister sur les caracterisations de spectres de neutrons a cause des problemes particulieremen t delicats que pose la mesure absolue de l'indice spectral et de la necessite de verifier les calculs au-dela des simples dimensions critiques. Les mesures constamment ameliorees de l'indice spectral, associees a la precision croissante des donnees microscopiques relatives aux materiaux utilises dans les detecteurs et
International Nuclear Information System (INIS)
Ettouney, Hisham; Alatiqi, Imad; Al-Sahali, Mohammad; Al-Hajirie, Khalida
2006-01-01
Energy storage is an attractive option to conserve limited energy resources, where more than 50% of the generated industrial energy is discarded in cooling water and stack gases. This study focuses on the evaluation of heat transfer enhancement in phase change energy storage units. The experiments are performed using spherical capsules filled with paraffin wax and metal beads. The experiments are conducted by inserting a single spherical capsule filled with wax and metal beads in a stream of hot/cold air. Experimental measurements include the temperature field within the spherical capsule and in the air stream. To determine the enhancement effects of the metal beads, the measured data is correlated against those for a spherical capsule filled with pure wax. Data analysis shows a reduction of 15% in the melting and solidification times upon increasing the number and diameter of the metal beads. This reduction is caused by a similar decrease in the thermal load of the sphere due to replacement of the wax by metal beads. The small size of the spherical capsule limits the enhancement effects; this is evident upon comparison of the heat transfer in a larger size, double pipe energy storage unit, where 2% of the wax volume is replaced with metal inserts, result in a three fold reduction in the melting/solidification time and a similar enhancement in the heat transfer rate
Spherical subjective refraction with a novel 3D virtual reality based system.
Pujol, Jaume; Ondategui-Parra, Juan Carlos; Badiella, Llorenç; Otero, Carles; Vilaseca, Meritxell; Aldaba, Mikel
To conduct a clinical validation of a virtual reality-based experimental system that is able to assess the spherical subjective refraction simplifying the methodology of ocular refraction. For the agreement assessment, spherical refraction measurements were obtained from 104 eyes of 52 subjects using three different methods: subjectively with the experimental prototype (Subj.E) and the classical subjective refraction (Subj.C); and objectively with the WAM-5500 autorefractor (WAM). To evaluate precision (intra- and inter-observer variability) of each refractive tool independently, 26 eyes were measured in four occasions. With regard to agreement, the mean difference (±SD) for the spherical equivalent (M) between the new experimental subjective method (Subj.E) and the classical subjective refraction (Subj.C) was -0.034D (±0.454D). The corresponding 95% Limits of Agreement (LoA) were (-0.856D, 0.924D). In relation to precision, intra-observer mean difference for the M component was 0.034±0.195D for the Subj.C, 0.015±0.177D for the WAM and 0.072±0.197D for the Subj.E. Inter-observer variability showed worse precision values, although still clinically valid (below 0.25D) in all instruments. The spherical equivalent obtained with the new experimental system was precise and in good agreement with the classical subjective routine. The algorithm implemented in this new system and its optical configuration has been shown to be a first valid step for spherical error correction in a semiautomated way. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.
Start-up of spherical tokamak without a center solenoid
International Nuclear Information System (INIS)
Maekawa, Takashi; Nagata, Masayoshi
2012-01-01
For low-aspect tokamak reactors, spherical tokamak reactors, ST-type FESF/CTFs, it is essential to remove or minimize a central solenoid (CS). Even with the minimized CS, non-inductive start up of the plasma current is required. Rapid increase in the spontaneous plasma current at the final stage of current start-up drives ignition. At the initial stage, formation of plasma and magnetic surfaces are required. As non-inductive plasma start-up scenarios, ECH/ECCD, LHCD, HHFW, DC HELICITY injection, plasma merging and NBI have been studied. In the present article, the present status and future prospect of experimental and theoretical works on these subjects. (author)
The basics of spherical tokamaks and progress in European research
International Nuclear Information System (INIS)
Gusev, V K; Alladio, F; Morris, A W
2003-01-01
When the aspect ratio of a tokamak (A = R/a) decreases significantly, there is a transformation of the well studied tokamak toroidal magnetic configuration into the spherical tokamak (ST) configuration. This configuration has high natural plasma elongation and triangularity and other unique equilibrium and stability properties of ST configuration, which are discussed in this paper. European research into ST physics is well advanced in spite of the young age of this branch of fusion science. An overview of selected experimental and theoretical results obtained at Ioffe, Culham and Frascati is given with the emphasis on their complementarity and links to the main stream of tokamak research, such as ITER. An outline of the basic ST advantages and the potential of ST research for new insights into magnetic confinement is also given. More detailed descriptions of recent advances in ST theory and experiment may be found in the invited papers by Akers and Ono in the proceedings of this conference
Alpha Anisotropy Studies of Near-Spherical and Deformed Nuclei
Van Duppen, P
2002-01-01
% IS329 \\\\ \\\\ Although it was the first decay mode to be discovered, the process of $\\alpha$-particle emission is still poorly understood. A few years ago the first systematic study of anisotropic $\\alpha$-decay triggered renewed theoretical interest. Nevertheless, today the theories are still not adequate enough and more experimental data are urgently needed. We therefore measure the $\\alpha$-anisotropies of the favoured transitions of a number of near-spherical Rn and At isotopes, and of deformed nuclei near A=220. As the different models yield contradictory predictions for the transitions that are investigated, the measurements will allow to discern on their validity. They will at the same time provide the necessary basis for further theoretical developments.
Spherical Pendulum Small Oscillations for Slewing Crane Motion
Directory of Open Access Journals (Sweden)
Alexander V. Perig
2014-01-01
Full Text Available The present paper focuses on the Lagrange mechanics-based description of small oscillations of a spherical pendulum with a uniformly rotating suspension center. The analytical solution of the natural frequencies’ problem has been derived for the case of uniform rotation of a crane boom. The payload paths have been found in the inertial reference frame fixed on earth and in the noninertial reference frame, which is connected with the rotating crane boom. The numerical amplitude-frequency characteristics of the relative payload motion have been found. The mechanical interpretation of the terms in Lagrange equations has been outlined. The analytical expression and numerical estimation for cable tension force have been proposed. The numerical computational results, which correlate very accurately with the experimental observations, have been shown.
Engineering feasibility of tight aspect ratio Tokamak (spherical torus) reactors
International Nuclear Information System (INIS)
Peng, Y-K.M.; Hicks, J.B.
1990-01-01
Engineering solutions are identified and analyzed for key high-power-density components of tight aspect ratio tokamak reactors (spherical torus reactors). The potentially extreme divertor heat loads can be reduced to about 3 MW/m 2 in expanded divertors using coils inside the demountable toroidal field coils. Given the long and narrow divertor channels, gaseous divertor targets become possible, which eliminate sputtering and increase the divertor life. The unshielded centre conductor post (CCP) of the toroidal field coil can be made of a single dispersion strengthened copper conductor cooled by high-velocity pressurized water to maintain acceptable copper temperature and strength. Damage and activation of the CCP at a neutron fluence of 10 MW-a/m 2 are also tolerable. Annual replacement of the centre post, the divertor assemblies and the blanket can be accomplished with vertical access for all torus components, which are modularized to reduce size and weight. The technical requirements of these solutions are shown to be comparable with, if not less demanding than, those estimated for conventional tokamak reactors. (author)
Nanoparticle Assemblies at Fluid Interfaces
Energy Technology Data Exchange (ETDEWEB)
Russell, Thomas P. [Univ. of Massachusetts, Amherst, MA (United States). Dept. of Polymer Science and Engineering
2015-03-10
A systematic study of the structure and dynamics of nanoparticles (NP) and NP-surfactants was performed. The ligands attached to both the NPs and NP-surfactants dictate the manner in which the nanoscopic materials assemble at fluid interfaces. Studies have shown that a single layer of the nanoscpic materials form at the interface to reduce the interactions between the two immiscible fluids. The shape of the NP is, also, important, where for spherical particles, a disordered, liquid-like monolayer forms, and, for nanorods, ordered domains at the interface is found and, if the monolayers are compressed, the orientation of the nanorods with respect to the interface can change. By associating end-functionalized polymers to the NPs assembled at the interface, NP-surfactants are formed that increase the energetic gain in segregating each NP at the interface which allows the NP-surfactants to jam at the interface when compressed. This has opened the possibility of structuring the two liquids by freezing in shape changes of the liquids.
Watermarking on 3D mesh based on spherical wavelet transform.
Jin, Jian-Qiu; Dai, Min-Ya; Bao, Hu-Jun; Peng, Qun-Sheng
2004-03-01
In this paper we propose a robust watermarking algorithm for 3D mesh. The algorithm is based on spherical wavelet transform. Our basic idea is to decompose the original mesh into a series of details at different scales by using spherical wavelet transform; the watermark is then embedded into the different levels of details. The embedding process includes: global sphere parameterization, spherical uniform sampling, spherical wavelet forward transform, embedding watermark, spherical wavelet inverse transform, and at last resampling the mesh watermarked to recover the topological connectivity of the original model. Experiments showed that our algorithm can improve the capacity of the watermark and the robustness of watermarking against attacks.
Heat loss investigation from spherical cavity receiver of solar concentrator
Energy Technology Data Exchange (ETDEWEB)
Shewale, V. C. [Dept. of Mechanical Engineering, NDMVPS KBT College of Engineering, Nashik (India); Dongarwar, P. R. [Dept. of Mechanical Engineering, College of Military Engineering, Pune (India); Gawande, R. P. [Dept. of Mechanical Engineering, B.D.C.O.E. Wardha, Nagpur University, NagpurI (India)
2016-11-15
The heat losses are mainly affects on the performance of cavity receiver of solar concentrator. In this paper, the experimental and numerical study is carried out for different heat losses from spherical cavity receiver of 0.385 m cavity diameter and 0.154 m opening diameter. The total and convection losses are studied experimentally to no wind and wind conditions for the temperature range of 150 °C to 300 °C at 0°, 30°, 45°, 60° and 90° inclination angle of cavity receiver. The experimental set up mainly consists of copper tube material cavity receiver wrapped with nichrome heating coil to heat the cavity and insulated with glasswool insulation. The numerical analysis was carried out with Fluent Computational fluid dynamics (CFD) software, to study connective heat losses for no wind condition only. The numerical results are compared with experimental results and found good agreement with maximum deviation of 12 %. The effect of inclination angle of cavity receiver on total losses and convection losses shows that as the inclination angle increases from 0o to 90o, both losses decreased due to decreased in convective zone into the cavity receiver. The effect of operating temperature of cavity shows that as the temperature of cavity receiver increases, the total and convective losses goes on increasing. The effect of external wind at 2 m/s and 4 m/s in two directions (side-on wind and head-on wind) is also studied experimentally for total and convective heat losses. The result shows that the heat losses are higher for head-on wind condition compared to side-on wind and no wind condition at all inclination angle of cavity receiver. The present results are also compared to the convective losses obtained from the correlations of Stine and Mcdonald and M. Prakash. The convective loss from these correlations shows nearest prediction to both experimental and numerical results.
Heat loss investigation from spherical cavity receiver of solar concentrator
International Nuclear Information System (INIS)
Shewale, V. C.; Dongarwar, P. R.; Gawande, R. P.
2016-01-01
The heat losses are mainly affects on the performance of cavity receiver of solar concentrator. In this paper, the experimental and numerical study is carried out for different heat losses from spherical cavity receiver of 0.385 m cavity diameter and 0.154 m opening diameter. The total and convection losses are studied experimentally to no wind and wind conditions for the temperature range of 150 °C to 300 °C at 0°, 30°, 45°, 60° and 90° inclination angle of cavity receiver. The experimental set up mainly consists of copper tube material cavity receiver wrapped with nichrome heating coil to heat the cavity and insulated with glasswool insulation. The numerical analysis was carried out with Fluent Computational fluid dynamics (CFD) software, to study connective heat losses for no wind condition only. The numerical results are compared with experimental results and found good agreement with maximum deviation of 12 %. The effect of inclination angle of cavity receiver on total losses and convection losses shows that as the inclination angle increases from 0o to 90o, both losses decreased due to decreased in convective zone into the cavity receiver. The effect of operating temperature of cavity shows that as the temperature of cavity receiver increases, the total and convective losses goes on increasing. The effect of external wind at 2 m/s and 4 m/s in two directions (side-on wind and head-on wind) is also studied experimentally for total and convective heat losses. The result shows that the heat losses are higher for head-on wind condition compared to side-on wind and no wind condition at all inclination angle of cavity receiver. The present results are also compared to the convective losses obtained from the correlations of Stine and Mcdonald and M. Prakash. The convective loss from these correlations shows nearest prediction to both experimental and numerical results
Directory of Open Access Journals (Sweden)
Jing Xu
2018-05-01
Full Text Available Bolted spherical joints are widely used to form space steel structures. The stiffness and load capacity of the structures are affected by the looseness of bolted spherical joint connections in the structures. The looseness of the connections, which can be caused by fabrication error, low modeling accuracy, and “false twist” in the installation process, may negatively impact the load capacity of the structure and even lead to severe accidents. Furthermore, it is difficult to detect bolted spherical joint connection looseness from the outside since the bolts connect spheres with rods together from the inside. Active sensing methods are proposed in this paper to monitor the tightness status of the bolted spherical connection using piezoceramic transducers. A triangle-on-triangle offset grid composed of bolted spherical joints and steel tube bars was fabricated as the specimen and was used to validate the active sensing methods. Lead Zirconate Titanate (PZT patches were used as sensors and actuators to monitor the bolted spherical joint tightness status. One PZT patch mounted on the central bolted sphere at the upper chord was used as an actuator to generate a stress wave. Another PZT patch mounted on the bar was used as a sensor to detect the propagated waves through the bolted spherical connection. The looseness of the connection can impact the energy of the stress wave propagated through the connection. The wavelet packet analysis and time reversal (TR method were used to quantify the energy of the transmitted signal between the PZT patches by which the tightness status of the connection can be detected. In order to verify the effectiveness, repeatability, and consistency of the proposed methods, the experiments were repeated six times in different bolted spherical connection positions. The experimental results showed that the wavelet packet analysis and TR method are effective in detecting the tightness status of the connections. The
Newnes electronics assembly handbook
Brindley, Keith
2013-01-01
Newnes Electronics Assembly Handbook: Techniques, Standards and Quality Assurance focuses on the aspects of electronic assembling. The handbook first looks at the printed circuit board (PCB). Base materials, basic mechanical properties, cleaning of assemblies, design, and PCB manufacturing processes are then explained. The text also discusses surface mounted assemblies and packaging of electromechanical assemblies, as well as the soldering process. Requirements for the soldering process; solderability and protective coatings; cleaning of PCBs; and mass solder/component reflow soldering are des
Liu, F.; Chen, S.; Lin, Q.; Wang, X. D.; Cao, J. X.
2018-01-01
The xonotlite crystals were synthesized via the hydrothermal synthesis manner from CaO and SiO2 as the raw materials with their Si/Ca molar ratio of 1.0. Comparative dynamics analysis on xonotlite spherical particles synthesized via hydrothermal synthesis process was explored in this paper. The accuracy of the dynamic equation of xonotlite spherical particles was verified by two methods, one was comparing the production rate of the xonotlite products calculated by the dynamic equation with the experimental values, and the other was comparing the apparent activation energies calculated by the dynamic equation with that calculated by the Kondo model. The results indicated that the production rates of the xonotlite spherical particles calculated by the dynamic equation were in good agreement with the experimental values and the apparent activation energy of the xonotlite spherical particles calculated by dynamic equation (84 kJ·mol-1) was close to that calculated by Kondo model (77 kJ·mol-1), verifying the high accuracy of the dynamic equation.
CFD study on NACA 4415 airfoil implementing spherical and sinusoidal Tubercle Leading Edge.
Directory of Open Access Journals (Sweden)
S M A Aftab
Full Text Available The Humpback whale tubercles have been studied for more than a decade. Tubercle Leading Edge (TLE effectively reduces the separation bubble size and helps in delaying stall. They are very effective in case of low Reynolds number flows. The current Computational Fluid Dynamics (CFD study is on NACA 4415 airfoil, at a Reynolds number 120,000. Two TLE shapes are tested on NACA 4415 airfoil. The tubercle designs implemented on the airfoil are sinusoidal and spherical. A parametric study is also carried out considering three amplitudes (0.025c, 0.05c and 0.075c, the wavelength (0.25c is fixed. Structured mesh is utilized to generate grid and Transition SST turbulence model is used to capture the flow physics. Results clearly show spherical tubercles outperform sinusoidal tubercles. Furthermore experimental study considering spherical TLE is carried out at Reynolds number 200,000. The experimental results show that spherical TLE improve performance compared to clean airfoil.
Novel, spherically-convergent ion systems for neutron source and fusion energy production
International Nuclear Information System (INIS)
Barnes, D.C.; Nebel, R.A.; Ribe, F.L.; Schauer, M.M.; Schranck, L.S.; Umstadter, K.R.
1999-01-01
Combining spherical convergence with electrostatic or electro-magnetostatic confinement of a nonneutral plasma offers the possibility of high fusion gain in a centimeter-sized system. The physics principles, scaling laws, and experimental embodiments of this approach are presented. Steps to development of this approach from its present proof-of-principle experiments to a useful fusion power reactor are outlined. This development path is much less expensive and simpler, compared to that for conventional magnetic confinement and leads to different and useful products at each stage. Reactor projections show both high mass power density and low to moderate wall loading. This approach is being tested experimentally in PFX-I (Penning Fusion eXperiment-Ions), which is based on the following recent advances: 1) Demonstration, in PFX (our former experiment), that it is possible to combine nonneutral electron plasma confinement with nonthermal, spherical focussing; 2) Theoretical development of the POPS (Periodically Oscillating Plasma Sphere) concept, which allows spherical compression of thermal-equilibrium ions; 3) The concept of a massively-modular approach to fusion power, and associated elimination of the critical problem of extremely high first wall loading. PFX-I is described. PFX-I is being designed as a small (<1.5 cm) spherical system into which moderate-energy electrons (up to 100 kV) are injected. These electrons are magnetically insulated from passing to the sphere and their space charge field is then used to spherically focus ions. Results of initial operation with electrons only are presented. Deuterium operation can produce significant neutron output with unprecedented efficiency (fusion gain Q). copyright 1999 American Institute of Physics
One-degree-of-freedom spherical model for the passive motion of the human ankle joint.
Sancisi, Nicola; Baldisserri, Benedetta; Parenti-Castelli, Vincenzo; Belvedere, Claudio; Leardini, Alberto
2014-04-01
Mathematical modelling of mobility at the human ankle joint is essential for prosthetics and orthotic design. The scope of this study is to show that the ankle joint passive motion can be represented by a one-degree-of-freedom spherical motion. Moreover, this motion is modelled by a one-degree-of-freedom spherical parallel mechanism model, and the optimal pivot-point position is determined. Passive motion and anatomical data were taken from in vitro experiments in nine lower limb specimens. For each of these, a spherical mechanism, including the tibiofibular and talocalcaneal segments connected by a spherical pair and by the calcaneofibular and tibiocalcaneal ligament links, was defined from the corresponding experimental kinematics and geometry. An iterative procedure was used to optimize the geometry of the model, able to predict original experimental motion. The results of the simulations showed a good replication of the original natural motion, despite the numerous model assumptions and simplifications, with mean differences between experiments and predictions smaller than 1.3 mm (average 0.33 mm) for the three joint position components and smaller than 0.7° (average 0.32°) for the two out-of-sagittal plane rotations, once plotted versus the full flexion arc. The relevant pivot-point position after model optimization was found within the tibial mortise, but not exactly in a central location. The present combined experimental and modelling analysis of passive motion at the human ankle joint shows that a one degree-of-freedom spherical mechanism predicts well what is observed in real joints, although its computational complexity is comparable to the standard hinge joint model.
Spherically symmetric self-similar universe
Energy Technology Data Exchange (ETDEWEB)
Dyer, C C [Toronto Univ., Ontario (Canada)
1979-10-01
A spherically symmetric self-similar dust-filled universe is considered as a simple model of a hierarchical universe. Observable differences between the model in parabolic expansion and the corresponding homogeneous Einstein-de Sitter model are considered in detail. It is found that an observer at the centre of the distribution has a maximum observable redshift and can in principle see arbitrarily large blueshifts. It is found to yield an observed density-distance law different from that suggested by the observations of de Vaucouleurs. The use of these solutions as central objects for Swiss-cheese vacuoles is discussed.
The generalized spherical model of ferromagnetic films
International Nuclear Information System (INIS)
Costache, G.
1977-12-01
The D→ infinity of the D-vectorial model of a ferromagnetic film with free surfaces is exactly solved. The mathematical mechanism responsible for the onset of a phase transition in the system is a generalized sticking phenomenon. It is shown that the temperature at which the sticking appears, the transition temperature of the model is monotonously increasing with increasing the number of layers of the film, contrary to what happens in the spherical model with overall constraint. Certain correlation inequalities of Griffiths type are shown to hold. (author)
The spherical tokamak fusion power plant
International Nuclear Information System (INIS)
Wilson, H.R.; Voss, G.; Ahn, J.W.
2003-01-01
The design of a 1GW(e) steady state fusion power plant, based on the spherical tokamak concept, has been further iterated towards a fully self-consistent solution taking account of plasma physics, engineering and neutronics constraints. In particular a plausible solution to exhaust handling is proposed and the steam cycle refined to further improve efficiency. The physics design takes full account of confinement, MHD stability and steady state current drive. It is proposed that such a design may offer a fusion power plant which is easy to maintain: an attractive feature for the power plants following ITER. (author)
The status of the Brazilian spherical detector
International Nuclear Information System (INIS)
Aguiar, O D; Andrade, L A; Filho, L Camargo; Costa, C A; Araujo, J C N de; Neto, E C de Rey; Souza, S T de; Fauth, A C; Frajuca, C; Frossati, G; Furtado, S R; Furtado, V G S; Magalhaes, N S; Jr, R M Marinho; Matos, E S; Meliani, M T; Melo, J L; Miranda, O D; Jr, N F Oliveira; Ribeiro, K L; Salles, K B M; Stellati, C; Jr, W F Velloso
2002-01-01
The first phase of the Brazilian Graviton Project is the construction and operation of the gravitational wave detector Mario Schenberg at the Physics Institute of the University of Sao Paulo. This gravitational wave spherical antenna is planned to feature a sensitivity better than h = 10 -21 Hz -1/2 at the 3.0-3.4 kHz bandwidth, and to work not only as a detector, but also as a testbed for the development of new technologies. Here we present the status of this detector
Spherical conformal models for compact stars
Energy Technology Data Exchange (ETDEWEB)
Takisa, P.M.; Maharaj, S.D.; Manjonjo, A.M.; Moopanar, S. [University of KwaZulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, Durban (South Africa)
2017-10-15
We consider spherical exact models for compact stars with anisotropic pressures and a conformal symmetry. The conformal symmetry condition generates an integral relationship between the gravitational potentials. We solve this condition to find a new anisotropic solution to the Einstein field equations. We demonstrate that the exact solution produces a relativistic model of a compact star. The model generates stellar radii and masses consistent with PSR J1614-2230, Vela X1, PSR J1903+327 and Cen X-3. A detailed physical examination shows that the model is regular, well behaved and stable. The mass-radius limit and the surface red shift are consistent with observational constraints. (orig.)
Galileon radiation from a spherical collapsing shell
Energy Technology Data Exchange (ETDEWEB)
Martín-García, Javier [Instituto de Física Teórica UAM/CSIC,C/ Nicolás Cabrera 15, E-28049 Madrid (Spain); Vázquez-Mozo, Miguel Á. [Instituto Universitario de Física Fundamental y Matemáticas (IUFFyM),Universidad de Salamanca, Plaza de la Merced s/n, E-37008 Salamanca (Spain)
2017-01-17
Galileon radiation in the collapse of a thin spherical shell of matter is analyzed. In the framework of a cubic Galileon theory, we compute the field profile produced at large distances by a short collapse, finding that the radiated field has two peaks traveling ahead of light fronts. The total energy radiated during the collapse follows a power law scaling with the shell’s physical width and results from two competing effects: a Vainshtein suppression of the emission and an enhancement due to the thinness of the shell.
Spherical Panoramas for Astrophysical Data Visualization
Kent, Brian R.
2017-05-01
Data immersion has advantages in astrophysical visualization. Complex multi-dimensional data and phase spaces can be explored in a seamless and interactive viewing environment. Putting the user in the data is a first step toward immersive data analysis. We present a technique for creating 360° spherical panoramas with astrophysical data. The three-dimensional software package Blender and the Google Spatial Media module are used together to immerse users in data exploration. Several examples employing these methods exhibit how the technique works using different types of astronomical data.
Geometrodynamics of spherically symmetric Lovelock gravity
International Nuclear Information System (INIS)
Kunstatter, Gabor; Taves, Tim; Maeda, Hideki
2012-01-01
We derive the Hamiltonian for spherically symmetric Lovelock gravity using the geometrodynamics approach pioneered by Kuchar (1994 Phys. Rev. D 50 3961) in the context of four-dimensional general relativity. When written in terms of the areal radius, the generalized Misner-Sharp mass and their conjugate momenta, the generic Lovelock action and Hamiltonian take on precisely the same simple forms as in general relativity. This result supports the interpretation of Lovelock gravity as the natural higher dimensional extension of general relativity. It also provides an important first step towards the study of the quantum mechanics, Hamiltonian thermodynamics and formation of generic Lovelock black holes. (fast track communication)
Three-dimensional plasmonic chiral tetramers assembled by DNA origami.
Shen, Xibo; Asenjo-Garcia, Ana; Liu, Qing; Jiang, Qiao; García de Abajo, F Javier; Liu, Na; Ding, Baoquan
2013-05-08
Molecular chemistry offers a unique toolkit to draw inspiration for the design of artificial metamolecules. For a long time, optical circular dichroism has been exclusively the terrain of natural chiral molecules, which exhibit optical activity mainly in the UV spectral range, thus greatly hindering their significance for a broad range of applications. Here we demonstrate that circular dichroism can be generated with artificial plasmonic chiral nanostructures composed of the minimum number of spherical gold nanoparticles required for three-dimensional (3D) chirality. We utilize a rigid addressable DNA origami template to precisely organize four nominally identical gold nanoparticles into a three-dimensional asymmetric tetramer. Because of the chiral structural symmetry and the strong plasmonic resonant coupling between the gold nanoparticles, the 3D plasmonic assemblies undergo different interactions with left and right circularly polarized light, leading to pronounced circular dichroism. Our experimental results agree well with theoretical predictions. The simplicity of our structure geometry and, most importantly, the concept of resorting on biology to produce artificial photonic functionalities open a new pathway to designing smart artificial plasmonic nanostructures for large-scale production of optically active metamaterials.
International Nuclear Information System (INIS)
Kartsev, I.S.; Eremenko, V.G.; Petrov, V.I.; Polenov, B.V.; Yudin, V.N.; Akatov, Yu.A.; Petrov, V.M.; Shurshakov, V.A.
2005-01-01
The design-structural features of the updated spherical phantom applied within the frameworks of the space experiment Matreshka-R at the Russian segment of International space station during ISS-8 and ISS-9 expeditions are described. The replacement of 48 polyethylene containers with TLD and STD assemblies by 16 cases installed from external side of the phantom and 4 tissue-equivalent caps of the central disk by 4 cases with detector assemblies is carried out. The updated tissue-equivalent phantom contains the active dosemeter based on 5 MOS detectors. The phantom cover is made from the non-flammable material NT-7. The basic characteristics of the flight specimen of the phantom are presented. The results of its on-Earth testing and real space flights are analyzed [ru
Characteristic wave velocities in spherical electromagnetic cloaks
International Nuclear Information System (INIS)
Yaghjian, A D; Maci, S; Martini, E
2009-01-01
We investigate the characteristic wave velocities in spherical electromagnetic cloaks, namely, phase, ray, group and energy-transport velocities. After deriving explicit expressions for the phase and ray velocities (the latter defined as the phase velocity along the direction of the Poynting vector), special attention is given to the determination of group and energy-transport velocities, because a cursory application of conventional formulae for local group and energy-transport velocities can lead to a discrepancy between these velocities if the permittivity and permeability dyadics are not equal over a frequency range about the center frequency. In contrast, a general theorem can be proven from Maxwell's equations that the local group and energy-transport velocities are equal in linear, lossless, frequency dispersive, source-free bianisotropic material. This apparent paradox is explained by showing that the local fields of the spherical cloak uncouple into an E wave and an H wave, each with its own group and energy-transport velocities, and that the group and energy-transport velocities of either the E wave or the H wave are equal and thus satisfy the general theorem.
Initial assessments of ignition spherical torus
International Nuclear Information System (INIS)
Peng, Y.K.M.; Borowski, S.K.; Bussell, G.T.
1985-12-01
Initial assessments of ignition spherical tori suggest that they can be highly cost effective and exceptionally small in unit size. Assuming advanced methods of current drive to ramp up the plasma current (e.g., via lower hybrid wave at modest plasma densities and temperatures), the inductive solenoid can largely be eliminated. Given the uncertainties in plasma energy confinement times and the effects of strong paramagnetism on plasma pressure, and allowing for the possible use of high-strength copper alloys (e.g., C-17510, Cu-Ni-Be alloy), ignition spherical tori with a 50-s burn are estimated to have major radii ranging from 1.0 to 1.6 m, aspect ratios from 1.4 to 1.7, vacuum toroidal fields from 2 to 3 T, plasma currents from 10 to 19 MA, and fusion power from 50 to 300 MW. Because of its modest field strength and simple poloidal field coil configuration, only conventional engineering approaches are needed in the design. A free-standing toroidal field coil/vacuum vessel structure is assessed to be feasible and relatively independent of the shield structure and the poloidal field coils. This exceptionally simple configuration depends significantly, however, on practical fabrication approaches of the center conductor post, about which there is presently little experience. 19 refs
Saltation of non-spherical sand particles.
Directory of Open Access Journals (Sweden)
Zhengshi Wang
Full Text Available Saltation is an important geological process and the primary source of atmospheric mineral dust aerosols. Unfortunately, no studies to date have been able to precisely reproduce the saltation process because of the simplified theoretical models used. For example, sand particles in most of the existing wind sand movement models are considered to be spherical, the effects of the sand shape on the structure of the wind sand flow are rarely studied, and the effect of mid-air collision is usually neglected. In fact, sand grains are rarely round in natural environments. In this paper, we first analyzed the drag coefficients, drag forces, and starting friction wind speeds of sand grains with different shapes in the saltation process, then established a sand saltation model that considers the coupling effect between wind and the sand grains, the effect of the mid-air collision of sand grains, and the effect of the sand grain shape. Based on this model, the saltation process and sand transport rate of non-spherical sand particles were simulated. The results show that the sand shape has a significant impact on the saltation process; for the same wind speed, the sand transport rates varied for different shapes of sand grains by as much as several-fold. Therefore, sand shape is one of the important factors affecting wind-sand movement.
Bidispersed Sphere Packing on Spherical Surfaces
Atherton, Timothy; Mascioli, Andrew; Burke, Christopher
Packing problems on spherical surfaces have a long history, originating in the classic Thompson problem of finding the ground state configuration of charges on a sphere. Such packings contain a minimal number of defects needed to accommodate the curvature; this is predictable using the Gauss-Bonnet theorem from knowledge of the topology of the surface and the local symmetry of the ordering. Famously, the packing of spherical particles on a sphere contains a 'scar' transition, where additional defects over those required by topology appear above a certain critical number of particles and self-organize into chains or scars. In this work, we study the packing of bidispersed packings on a sphere, and hence determine the interaction of bidispersity and curvature. The resultant configurations are nearly crystalline for low values of bidispersity and retain scar-like structures; these rapidly become disordered for intermediate values and approach a so-called Appollonian limit at the point where smaller particles can be entirely accommodated within the voids left by the larger particles. We connect our results with studies of bidispersed packings in the bulk and on flat surfaces from the literature on glassy systems and jamming. Supported by a Cottrell Award from the Research Corporation for Science Advancement.
Crack propagation on spherical pressure vessels
International Nuclear Information System (INIS)
Lebey, J.; Roche, R.
1975-01-01
The risk presented by a crack on a pressure vessel built with a ductile steel cannot be well evaluated by simple application of the rules of Linear Elastic Fracture Mechanics, which only apply to brittle materials. Tests were carried out on spherical vessels of three different scales built with the same steel. Cracks of different length were machined through the vessel wall. From the results obtained, crack initiation stress (beginning of stable propagation) and instable propagation stress may be plotted against the lengths of these cracks. For small and medium size, subject to ductile fracture, the resulting curves are identical, and may be used for ductile fracture prediction. Brittle rupture was observed on larger vessels and crack propagation occurred at lower stress level. Preceedings curves are not usable for fracture analysis. Ultimate pressure can be computed with a good accuracy by using equivalent energy toughness, Ksub(1cd), characteristic of the metal plates. Satisfactory measurements have been obtained on thin samples. The risks of brittle fracture may then judged by comparing Ksub(1cd) with the calculated K 1 value, in which corrections for vessel shape are taken into account. It is thus possible to establish the bursting pressure of cracked spherical vessels, with the help of two rules, one for brittle fracture, the other for ductile instability. A practical method is proposed on the basis of the work reported here
Simulations of curved assemblies in soft matter and biological systems
Qiao, Cong
Viruses are small infectious agents that replicate only inside living cells of other organisms. In the viral life cycle, the self-assembly of the outer protein shell (capsid) is an essential step. We study this process in the hope of shedding light on development of antiviral drugs, gene therapy and other virus-related technologies that can benefit the humankind. More fundamentally, learning about the process of viral capsid assembly can elucidate the assembly mechanisms of a wide range of complex structures. In this work, we use molecular dynamics simulations and coarse-grained computational models to study viral capsid assembly in several situations where geometric constraints play a role in dictating assembly outcomes. We first focus on icosahedral viruses with single-stranded RNA genomes, in which case the capsid usually assembles around the genomic RNA. It is consistently observed in experiments that such viral particles are ''overcharged'', meaning the net negative charge on the viral genome is greater than the net positive charge on the viral capsid. We computationally investigate the mechanisms that lead to ``overcharging'', and more broadly, how the encapsidated genome length is influenced by the capsid. We perform both dynamical simulations of the assembly process and equilibrium calculations to determine the optimal genome length (meaning that which maximizes the assembly yield and/or minimizes the free energy of the assembled virus). We find that the optimal genome length is determined by the interplay between capsid size, net capsid charge, distribution of capsid charge and nucleic acid structures. Our simulations demonstrate that overcharging results from a combination of electrostatic screening and the geometric constraints associated with encapsulating a nucleic acid inside of a spherical virus. We then study the assembly of the immature HIV. In contrast to icosahedral viruses, the immature HIV forms an asymmetric particle, consisting of continuous
Operational Regimes of the National Spherical Torus Experiment; TOPICAL
International Nuclear Information System (INIS)
D. Mueller; M.G. Bell; R.E. Bell; M. Bitter; T. Bigelow; P. Bonoli; M. Carter; J. Ferron; E. Fredrickson; D. Gates; L. Grisham; J.C. Hosea; D. Johnson; R. Kaita; S.M. Kaye; H. Kugel; B.P. LeBlanc; R. Maingi; R. Majeski; R. Maqueda; J. Menard; M. Ono; F. Paoletti; S. Paul; C.K. Phillips; R. Pinsker; R. Raman; S.A. Sabbagh; C.H. Skinner; V.A. Soukhanovskii; D. Stutman; D. Swain; Y. Takase; J. Wilgen; J.R. Wilson; G.A. Wurden; S. Zweben
2002-01-01
The National Spherical Torus Experiment (NSTX) is a proof-of-principle experiment designed to study the physics of Spherical Tori (ST), i.e., low-aspect-ratio toroidal plasmas. Important issues for ST research are whether the high-eta stability and reduced transport theoretically predicted for this configuration can be realized experimentally. In NSTX, the commissioning of a digital real-time plasma control system, the provision of flexible heating systems, and the application of wall conditioning techniques were instrumental in achieving routine operation with good confinement. NSTX has produced plasmas with R/a(approx) 0.85 m/0.68 m, A(approx) 1.25, Ip* 1.1 MA, BT= 0.3-0.45 T, k* 2.2, d* 0.5, with auxiliary heating by up to 4 MW of High Harmonic Fast Waves, and 5 MW of 80 keV D0 Neutral Beam Injection (NBI). The energy confinement time in plasmas heated by NBI has exceeded 100 ms and a toroidal beta (bT= 2m0 and lt;p and gt;/BT02, where BT0 is the central vacuum toroidal magnetic field) up to 22% has be en achieved. HHFW power of 2.3 MW has increased the electron temperature from an initial 0.4 keV to 0.9 keV both with and without producing a significant density rise in the plasma. The early application of both NBI and HHFW heating has slowed the penetration of the inductively produced plasma current, modifying the current profile and, thereby, the observed MHD stability
Operational Regimes of the National Spherical Torus Experiment
International Nuclear Information System (INIS)
Mueller, D.; Bell, M.G.; Bell, R.E.; Bitter, M.; Bigelow, T.; Bonoli, P.; Carter, M.; Ferron, J.; Fredrickson, E.; Gates, D.; Grisham, L.; Hosea, J.C.; Johnson, D.; Kaita, R.; Kaye, S.M.; Kugel, H.; LeBlanc, B.P.; Maingi, R.; Majeski, R.; Maqueda, R.; Menard, J.; Ono, M.; Paoletti, F.; Paul, S.; Phillips, C.K.; Pinsker, R.; Raman, R.; Sabbagh, S.A.; Skinner, C.H.; Soukhanovskii, V.A; Stutman, D.; Swain, D.; Takase, Y.; Wilgen, J.; Wilson, J.R.; Wurden, G.A.; Zweben, S.
2002-01-01
The National Spherical Torus Experiment (NSTX) is a proof-of-principle experiment designed to study the physics of Spherical Tori (ST), i.e., low-aspect-ratio toroidal plasmas. Important issues for ST research are whether the high-eta stability and reduced transport theoretically predicted for this configuration can be realized experimentally. In NSTX, the commissioning of a digital real-time plasma control system, the provision of flexible heating systems, and the application of wall conditioning techniques were instrumental in achieving routine operation with good confinement. NSTX has produced plasmas with R/a ∼ 0.85 m/0.68 m, A ∼ 1.25, Ip * 1.1 MA, BT = 0.3-0.45 T, k * 2.2, d * 0.5, with auxiliary heating by up to 4 MW of High Harmonic Fast Waves, and 5 MW of 80 keV D0 Neutral Beam Injection (NBI). The energy confinement time in plasmas heated by NBI has exceeded 100 ms and a toroidal beta (bT = 2m0 /BT02, where BT0 is the central vacuum toroidal magnetic field) up to 22% has be en achieved. HHFW power of 2.3 MW has increased the electron temperature from an initial 0.4 keV to 0.9 keV both with and without producing a significant density rise in the plasma. The early application of both NBI and HHFW heating has slowed the penetration of the inductively produced plasma current, modifying the current profile and, thereby, the observed MHD stability
Thermal behaviour of a spherical addition to molten metals
Energy Technology Data Exchange (ETDEWEB)
Roehmen, E.
1995-05-01
This thesis presents a numerical model for describing the thermal behaviour of a spherical alloy addition when added to a melt. It is assumed that: no significant heat of solution between the alloy addition and the melt is involved, the dissolution rate is dominated by heat transfer from the melt, the heat flow into the addition is spherically symmetric, the additions have a well defined melting point, there are no solid phase transformations, heat conduction can be represented by Fourier`s law, and the heat transfer from the melt can be described by an average heat transfer coefficient. The model is validated by comparison with experimental data obtained from immersion experiments on: (1) a 4.88 cm diameter Al sphere chilled in liquid nitrogen to -196 {sup o}C and then immersed in water of 3.8 {sup o}C and 18.1 {sup o}C, (2) 4.90 cm diameter Al spheres at room temperatures immersed in molten Al of 720 {sup o}C, and (3) 3.72 cm diameter 75 wt% FeSi spheres at 150 {sup o}C immersed in molten steel of 1600 {sup o}C. The shell thickness and temperatures at the sphere centre and surface were recorded as functions of time. For model and experiment to agree, it was found that the density, specific heat and thermal conductivity of the alloy addition must depend on temperature, and an inner heat transfer resistance across the sphere-shell interphase must be included. The sensible heat of the melt that solidifies should be included in the heat balance only when the shell is expanding. The inner heat transfer resistance is shown to be very important in determining the melting/dissolution time for alloy additions that react strongly with the melt. 70 refs., 60 figs., 36 tabs.
PRACTICAL CONTRIBUTIONS TO THE STUDY OF RESISTANCE ASSEMBLIES MADE WITH WARP KNITS
OANA Ioan-Pavel; OANA Dorina
2014-01-01
Based on the principle that a body to be obtained by sewing the material to provide resistance and the like in the stitching assembly, the experimental study of which developed resistance is compared with the resistance materials to effectively assembled by the assembly line. The experimental values resistance for assemblies were obtained in the testing for resistance to sliding stitch ASTM D 434 using Tinius Olsen HK5T test type machine. The assembly strength was determined for warp knit...
Measurement of Turbulence Modulation by Non-Spherical Particles
DEFF Research Database (Denmark)
Mandø, Matthias; Rosendahl, Lasse
2010-01-01
The change in the turbulence intensity of an air jet resulting from the addition of particles to the flow is measured using Laser Doppler Anemometry. Three distinct shapes are considered: the prolate spheroid, the disk and the sphere. Measurements of the carrier phase and particle phase velocities...... at the centerline of the jet are carried out for mass loadings of 0.5, 1, 1.6 and particle sizes 880μm, 1350μm, 1820μm for spherical particles. For each non-spherical shape only a single size and loading are considered. The turbulence modulation of the carrier phase is found to highly dependent on the turbulence......, the particle mass flow and the integral length scale of the flow. The expression developed on basis of spherical particles only is applied on the data for the non-spherical particles. The results suggest that non-spherical particles attenuate the carrier phase turbulence significantly more than spherical...
Density- and wavefunction-normalized Cartesian spherical harmonics for l ≤ 20.
Michael, J Robert; Volkov, Anatoliy
2015-03-01
The widely used pseudoatom formalism [Stewart (1976). Acta Cryst. A32, 565-574; Hansen & Coppens (1978). Acta Cryst. A34, 909-921] in experimental X-ray charge-density studies makes use of real spherical harmonics when describing the angular component of aspherical deformations of the atomic electron density in molecules and crystals. The analytical form of the density-normalized Cartesian spherical harmonic functions for up to l ≤ 7 and the corresponding normalization coefficients were reported previously by Paturle & Coppens [Acta Cryst. (1988), A44, 6-7]. It was shown that the analytical form for normalization coefficients is available primarily for l ≤ 4 [Hansen & Coppens, 1978; Paturle & Coppens, 1988; Coppens (1992). International Tables for Crystallography, Vol. B, Reciprocal space, 1st ed., edited by U. Shmueli, ch. 1.2. Dordrecht: Kluwer Academic Publishers; Coppens (1997). X-ray Charge Densities and Chemical Bonding. New York: Oxford University Press]. Only in very special cases it is possible to derive an analytical representation of the normalization coefficients for 4 4 the density normalization coefficients were calculated numerically to within seven significant figures. In this study we review the literature on the density-normalized spherical harmonics, clarify the existing notations, use the Paturle-Coppens (Paturle & Coppens, 1988) method in the Wolfram Mathematica software to derive the Cartesian spherical harmonics for l ≤ 20 and determine the density normalization coefficients to 35 significant figures, and computer-generate a Fortran90 code. The article primarily targets researchers who work in the field of experimental X-ray electron density, but may be of some use to all who are interested in Cartesian spherical harmonics.
The use of rotating electric are for spherical particle production
Directory of Open Access Journals (Sweden)
Bica, Ion
2000-08-01
Full Text Available This work presents an experimental device designed to obtain spherical partióles by means of a rotating electric are. A rotation frequency of the electric are of 750 s^{-1}, a voltage of 50 V (dc and a current of 100 A was used. The mass flow rate was 3 g.min^{-1}. Under these conditions particles of 15 to 20 μm in diameter were obtained.
Este trabajo presenta la instalación experimental destinada a la obtención de partículas esféricas utilizando un arco eléctrico rotatorio. Para ello se utilizó una frecuencia de rotación del arco eléctrico de 750 s^{-1} a un voltaje del arco de 50 V (cc y una corriente de 100 A. La velocidad de flujo de materia fue de 3 g.min^{-1} obteniéndose partículas de diámetros comprendidos entre 15 y 20 μm.
On the submerging of a spherical intruder into granular beds
Directory of Open Access Journals (Sweden)
Wu Chuan-Yu
2017-01-01
Full Text Available Granular materials are complex systems and their mechanical behaviours are determined by the material properties of individual particles, the interaction between particles and the surrounding media, which are still incompletely understood. Using an advanced discrete element method (DEM, we simulate the submerging process of a spherical projectile (an intruder into granular materials of various properties with a zero penetration velocity (i.e. the intruder is touching the top surface of the granular bed and released from stationary and examine its settling behaviour. By systematically changing the density and size of the intruder and the particle density (i.e. the density of the particles in the granular bed, we find that the intruder can sink deep into the granular bed even with a zero penetration velocity. Furthermore, we confirm that under certain conditions the granular bed can behave like a Newtonian liquid and the submerging intruder can reach a constant velocity, i.e. the terminal velocity, identical to the settling of a sphere in a liquid, as observed experimentally. A mathematical model is also developed to predict the maximum penetration depth of the intruder. The model predictions are compared with experimental data reported in the literature,good agreement was obtained, demonstrating the model can accurately predict the submerging behaviour of the intruder in the granular media.
Non-Spherical Gravitational Collapse of Strange Quark Matter
Institute of Scientific and Technical Information of China (English)
Zade S S; Patil K D; Mulkalwar P N
2008-01-01
We study the non-spherical gravitational collapse of the strange quark null fluid.The interesting feature which emerges is that the non-spherical collapse of charged strange quark matter leads to a naked singularity whereas the gravitational collapse of neutral quark matter proceeds to form a black hole.We extend the earlier work of Harko and Cheng[Phys.Lett.A 266 (2000) 249]to the non-spherical case.
Spherical solitons in Earth’S mesosphere plasma
International Nuclear Information System (INIS)
Annou, K.; Annou, R.
2016-01-01
Soliton formation in Earth’s mesosphere plasma is described. Nonlinear acoustic waves in plasmas with two-temperature ions and a variable dust charge where transverse perturbation is dealt with are studied in bounded spherical geometry. Using the perturbation method, a spherical Kadomtsev–Petviashvili equation that describes dust acoustic waves is derived. It is found that the parameters taken into account have significant effects on the properties of nonlinear waves in spherical geometry
On the phase diagram of non-spherical nanoparticles
Wautelet, M; Hecq, M
2003-01-01
The phase diagram of nanoparticles is known to be a function of their size. In the literature, this is generally demonstrated for cases where their shape is spherical. Here, it is shown theoretically that the phase diagram of non-spherical particles may be calculated from the spherical case, at the same surface area/volume ratio, both with and without surface segregation, provided the surface tension is considered to be isotropic.
International Nuclear Information System (INIS)
Jabsen, F.S.
1979-01-01
This invention is directed toward a nuclear fuel assembly guide tube arrangement which restrains spacer grid movement due to coolant flow and which offers secondary means for supporting a fuel assembly during handling and transfer operations
On three-dimensional spherical acoustic cloaking
International Nuclear Information System (INIS)
Munteanu, Ligia; Chiroiu, Veturia
2011-01-01
Transformation acoustics opens a new avenue towards the design of acoustic metamaterials, which are materials engineered at the subwavelength scale in order to mimic the parameters in wave equations. The design of the acoustic cloaking is based on the property of equations being invariant under a coordinate transformation, i.e. a specific spatial compression is equivalent to a variation of the material parameters in the original space. In this paper, the sound invisibility performance is discussed for spherical cloaks. The original domain consists of alternating concentric layers made from piezoelectric ceramics and epoxy resin, following a triadic Cantor sequence. The spatial compression, obtained by applying the concave-down transformation, leads to an equivalent domain with an inhomogeneous and anisotropic distribution of the material parameters.
Nuclear structure investigations on spherical nuclei
International Nuclear Information System (INIS)
Heisenberg, J.; Calarco, J.; Dawson, J.; Hersman, F.W.
1989-09-01
This report discusses the following topics: electron scattering studies on spherical nuclei; electron scattering from collective states in deformed nuclei; proton and pion scattering studies; 12 C(e,e'p) and 16 O(e,e'p); 12 C(e,e'α) and 16 O(e,e'α); studies at high q at Bates; measurements with rvec e at Bates; 12 C(γ,p); future directions in giant resonance studies; proton knockout from 16 O; quasielastic studies at Bates; triple coincidence studies of nuclear correlations; contributions to (e,e'2p) at KIKHEF; contributions to instrumentation at CEBAF; instrumentation development at UNH; the Bates large acceptance spectrometer toroid; shell model and core polarization calculations; and the relativistic nuclear model
Coulomb potentials between spherical heavy ions
International Nuclear Information System (INIS)
Iwe, H.
1982-01-01
The Coulomb interaction between spherical nuclei having arbitrary radial nuclear charge distributions is calculated. All these realistic Coulomb potentials are given in terms of analytical expressions and are available for immediate application. So in no case a numerical computation of the Coulomb integral is required. The parameters of the charge distributions are taken from electron scattering analysis. The Coulomb self-energies of the charge distributions used are also calculated analytically in a closed form. For a number of nucleus-nucleus pairs, the Coulomb potentials derived from realistic charge distributions are compared with those normally used in various nucleus-nucleus optical model calculations. In this connection a detailed discussion of the problem how to choose consistently Coulomb parameters for different approximations is given. (orig.)
Application studies of spherical tokamak plasma merging
International Nuclear Information System (INIS)
Ono, Yasushi; Inomoto, Michiaki
2012-01-01
The experiment of plasma merging and heating has long history in compact torus studies since Wells. The study of spherical tokamak (ST), starting from TS-3 plasma merging experiment of Tokyo University in the late 1980s, is followed by START of Culham laboratory in the 1900s, TS-4 and UTST of Tokyo University and MAST of Culham laboratory in the 2000s, and last year by VEST of Soul University. ST has the following advantages: 1) plasma heating by magnetic reconnection at a MW-GW level, 2) rapid start-up of high beta plasma, 3) current drive/flux multiplication and distribution control of ST plasma, 4) fueling and helium-ash exhaust. In the present article, we emphasize that magnetic reconnection and plasma merging phenomena are important in ST plasma study as well as in plasma physics. (author)
Confined detonations with cylindrical and spherical symmetry
International Nuclear Information System (INIS)
Linan, A.; Lecuona, A.
1979-01-01
An imploding spherical or cylindrical detonation, starting in the interface of the detonantion with an external inert media, used as a reflector, creates on it a strong shock wave moving outward from the interface. An initially weak shock wave appears in the detonated media that travels toward the center, and it could reach the detonation wave, enforcing it in its process of implosion. To describe the fluid field, the Euler s equations are solved by means of expansions valid for the early stages of the process. Isentropic of the type P/pγ-K for the detonated and compressed inert media are used. For liquid or solid reflectors a more appropriate equation is used. (Author) 8 refs
Simple spherical ablative-implosion model
International Nuclear Information System (INIS)
Mayer, F.J.; Steele, J.T.; Larsen, J.T.
1980-01-01
A simple model of the ablative implosion of a high-aspect-ratio (shell radius to shell thickness ratio) spherical shell is described. The model is similar in spirit to Rosenbluth's snowplow model. The scaling of the implosion time was determined in terms of the ablation pressure and the shell parameters such as diameter, wall thickness, and shell density, and compared these to complete hydrodynamic code calculations. The energy transfer efficiency from ablation pressure to shell implosion kinetic energy was examined and found to be very efficient. It may be possible to attach a simple heat-transport calculation to our implosion model to describe the laser-driven ablation-implosion process. The model may be useful for determining other energy driven (e.g., ion beam) implosion scaling
Space Propulsion via Spherical Torus Fusion Reactor
International Nuclear Information System (INIS)
Williams, Craig H.; Juhasz, Albert J.; Borowski, Stanley K.; Dudzinski, Leonard A.
2003-01-01
A conceptual vehicle design enabling fast outer solar system travel was produced predicated on a small aspect ratio spherical torus nuclear fusion reactor. Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous in 204 days, with an initial mass in low Earth orbit of 1630 mt. Engineering conceptual design, analysis, and assessment were performed on all major systems including nuclear fusion reactor, magnetic nozzle, power conversion, fast wave plasma heating, fuel pellet injector, startup/re-start fission reactor and battery, and other systems. Detailed fusion reactor design included analysis of plasma characteristics, power balance and utilization, first wall, toroidal field coils, heat transfer, and neutron/X-ray radiation
Canonical quantization of static spherically symmetric geometries
International Nuclear Information System (INIS)
Christodoulakis, T; Dimakis, N; Terzis, P A; Doulis, G; Grammenos, Th; Melas, E; Spanou, A
2013-01-01
The conditional symmetries of the reduced Einstein–Hilbert action emerging from a static, spherically symmetric geometry are used as supplementary conditions on the wave function. Based on their integrability conditions, only one of the three existing symmetries can be consistently imposed, while the unique Casimir invariant, being the product of the remaining two symmetries, is calculated as the only possible second condition on the wave function. This quadratic integral of motion is identified with the reparametrization generator, as an implication of the uniqueness of the dynamical evolution, by fixing a suitable parametrization of the r-lapse function. In this parametrization, the determinant of the supermetric plays the role of the mesure. The combined Wheeler – DeWitt and linear conditional symmetry equations are analytically solved. The solutions obtained depend on the product of the two ''scale factors''
Laser Pulse Heating of Spherical Metal Particles
Directory of Open Access Journals (Sweden)
Michael I. Tribelsky
2011-12-01
Full Text Available We consider the general problem of laser pulse heating of spherical metal particles with the sizes ranging from nanometers to millimeters. We employ the exact Mie solution of the diffraction problem and solve the heat-transfer equation to determine the maximum temperature rise at the particle surface as a function of optical and thermometric parameters of the problem. Primary attention is paid to the case when the thermal diffusivity of the particle is much larger than that of the environment, as it is in the case of metal particles in fluids. We show that, in this case, for any given duration of the laser pulse, the maximum temperature rise as a function of the particle size reaches a maximum at a certain finite size of the particle. We suggest simple approximate analytical expressions for this dependence, which cover the entire parameter range of the problem and agree well with direct numerical simulations.
Spherical Nb single crystals containerlessly grown by electrostatic levitation
International Nuclear Information System (INIS)
Sung, Y.S.; Takeya, H.; Hirata, K.; Togano, K.
2003-01-01
Spherical Nb (T m =2750 K) single crystals were grown via containerless electrostatic levitation (ESL). Samples became spherical at melting in levitation and undercooled typically 300-450 K prior to nucleation. As-processed samples were still spherical without any macroscopic shape change by solidification showing a uniform dendritic surface morphology. Crystallographic {111} planes exposed in equilateral triangular shapes on the surface by preferential macroetching and spotty back-reflection Laue patterns confirm the single crystal nature of the ESL-processed Nb samples. No hysteresis in magnetization between zero field and field cooling also implies a clean defect-free condition of the spherical Nb single crystals
Low-Q Electrically Small Spherical Magnetic Dipole Antennas
DEFF Research Database (Denmark)
Kim, Oleksiy S.
2010-01-01
Three novel electrically small antenna configurations radiating a TE10 spherical mode corresponding to a magnetic dipole are presented and investigated: multiarm spherical helix (MSH) antenna, spherical split ring resonator (S-SRR) antenna, and spherical split ring (SSR) antenna. All three antennas...... are self-resonant, with the input resistance tuned to 50 ohms by an excitation curved dipole/monopole. A prototype of the SSR antenna has been fabricated and measured, yielding results that are consistent with the numerical simulations. Radiation quality factors (Q) of these electrically small antennas (in...
Fluid Fuel Fluctuations in the Spherical Tank
Directory of Open Access Journals (Sweden)
H. D. Nguyen
2014-01-01
Full Text Available Many authors tried to solve a task concerning small fluctuations of the incompressible ideal liquid, which partially fills a stationary tank of any shape. There is a long list of references to this subject. The article presents a task solution on own fluctuations of liquid in spherical capacity, with boundary conditions on a free surface and a surface with a resistance – drain surface. Relevance of problem consists in assessment of influence of intra tank devices (measuring, intaking, damping devices, etc. on the liquid fuel fluctuations. The special attention is paid to finding the own values and frequencies of the equations of disturbed flow fluctuations with dissipation available on the boundary surfaces. In contrast to the previous examples, the lowering speed and the free surface area at undisturbed state are variable.The article also considers a variation formulation of the auxiliary boundary tasks. In solution of variation tasks, the attached Legendre's functions were used as coordinate functions. Further, after substitution of the variation tasks solution in the boundary conditions and the subsequent mathematical operations the characteristic equation was obtained. To obtain solutions of the cubic characteristic equation Cardano formulas were used. The article also considers the task on the own motions of liquid filling a capacity between two concentric spheres and flowing out via the intake in case there is a free surface. Reliability of the obtained numerical results is confirmed by comparison with calculation results of frequencies resulting from solutions of a task on the own fluctuations of liquid in the spherical capacity with the constant depth of liquid. All numerical calculations were performed using the Matlab environment.
Polymer Directed Protein Assemblies
van Rijn, Patrick
2013-01-01
Protein aggregation and protein self-assembly is an important occurrence in natural systems, and is in some form or other dictated by biopolymers. Very obvious influences of biopolymers on protein assemblies are, e. g., virus particles. Viruses are a multi-protein assembly of which the morphology is
International Nuclear Information System (INIS)
Sasaki, Y.; Tashima, J.
1975-01-01
A description is given of nuclear reactor fuel assemblies arranged in the form of a lattice wherein there is attached to the interface of one of two adjacent fuel assemblies a plate spring having a concave portion curved toward said interface and to the interface of the other fuel assembly a plate spring having a convex portion curved away from said interface
Convolutional Neural Network-Based Robot Navigation Using Uncalibrated Spherical Images.
Ran, Lingyan; Zhang, Yanning; Zhang, Qilin; Yang, Tao
2017-06-12
Vision-based mobile robot navigation is a vibrant area of research with numerous algorithms having been developed, the vast majority of which either belong to the scene-oriented simultaneous localization and mapping (SLAM) or fall into the category of robot-oriented lane-detection/trajectory tracking. These methods suffer from high computational cost and require stringent labelling and calibration efforts. To address these challenges, this paper proposes a lightweight robot navigation framework based purely on uncalibrated spherical images. To simplify the orientation estimation, path prediction and improve computational efficiency, the navigation problem is decomposed into a series of classification tasks. To mitigate the adverse effects of insufficient negative samples in the "navigation via classification" task, we introduce the spherical camera for scene capturing, which enables 360° fisheye panorama as training samples and generation of sufficient positive and negative heading directions. The classification is implemented as an end-to-end Convolutional Neural Network (CNN), trained on our proposed Spherical-Navi image dataset, whose category labels can be efficiently collected. This CNN is capable of predicting potential path directions with high confidence levels based on a single, uncalibrated spherical image. Experimental results demonstrate that the proposed framework outperforms competing ones in realistic applications.
Convolutional Neural Network-Based Robot Navigation Using Uncalibrated Spherical Images
Directory of Open Access Journals (Sweden)
Lingyan Ran
2017-06-01
Full Text Available Vision-based mobile robot navigation is a vibrant area of research with numerous algorithms having been developed, the vast majority of which either belong to the scene-oriented simultaneous localization and mapping (SLAM or fall into the category of robot-oriented lane-detection/trajectory tracking. These methods suffer from high computational cost and require stringent labelling and calibration efforts. To address these challenges, this paper proposes a lightweight robot navigation framework based purely on uncalibrated spherical images. To simplify the orientation estimation, path prediction and improve computational efficiency, the navigation problem is decomposed into a series of classification tasks. To mitigate the adverse effects of insufficient negative samples in the “navigation via classification” task, we introduce the spherical camera for scene capturing, which enables 360° fisheye panorama as training samples and generation of sufficient positive and negative heading directions. The classification is implemented as an end-to-end Convolutional Neural Network (CNN, trained on our proposed Spherical-Navi image dataset, whose category labels can be efficiently collected. This CNN is capable of predicting potential path directions with high confidence levels based on a single, uncalibrated spherical image. Experimental results demonstrate that the proposed framework outperforms competing ones in realistic applications.
International Nuclear Information System (INIS)
Okamura, M.; Sori, N.; Saito, A.
1997-01-01
Various magnetic regenerator materials, such as Er 3 Ni, Er 3 Co and ErNi, are fabricated in the form of a spherical particle by a rapid solidification process. 4 K level refrigeration has been obtained by a GM refrigerator using these materials. However, the magnetic regenerator materials are considered brittle, as they are intermetallic compounds. It is important to evaluate the mechanical properties of these materials to confirm reliability as a regenerator material. In this paper, experimental results of compression and vibration tests for magnetic regenerator materials are described. The technical point of this study is to use spherical particles as test samples. The compressive stress of 20 MPa was applied to these spherical particles and no fractured spheres were observed. Similarly, no fractured spheres were found after the vibration test, in which the maximum acceleration was 30 X 9.8 m/s 2 and the number of vibration times was 1 X 10 6 , insofar as there was no room to stir spherical particles in a regenerator. In practice, the reliability of magnetic regenerator materials has been confirmed by a long-run test of 7,000 h in a usual GM refrigerator
Eccentricity in Images of Circular and Spherical Targets and its Impact to 3D Object Reconstruction
Directory of Open Access Journals (Sweden)
T. Luhmann
2014-06-01
Full Text Available This paper discusses a feature of projective geometry which causes eccentricity in the image measurement of circular and spherical targets. While it is commonly known that flat circular targets can have a significant displacement of the elliptical image centre with respect to the true imaged circle centre, it can also be shown that the a similar effect exists for spherical targets. Both types of targets are imaged with an elliptical contour. As a result, if measurement methods based on ellipses are used to detect the target (e.g. best-fit ellipses, the calculated ellipse centre does not correspond to the desired target centre in 3D space. This paper firstly discusses the use and measurement of circular and spherical targets. It then describes the geometrical projection model in order to demonstrate the eccentricity in image space. Based on numerical simulations, the eccentricity in the image is further quantified and investigated. Finally, the resulting effect in 3D space is estimated for stereo and multi-image intersections. It can be stated that the eccentricity is larger than usually assumed, and must be compensated for high-accuracy applications. Spherical targets do not show better results than circular targets. The paper is an updated version of Luhmann (2014 new experimental investigations on the effect of length measurement errors.
Spherical harmonics coefficients for ligand-based virtual screening of cyclooxygenase inhibitors.
Wang, Quan; Birod, Kerstin; Angioni, Carlo; Grösch, Sabine; Geppert, Tim; Schneider, Petra; Rupp, Matthias; Schneider, Gisbert
2011-01-01
Molecular descriptors are essential for many applications in computational chemistry, such as ligand-based similarity searching. Spherical harmonics have previously been suggested as comprehensive descriptors of molecular structure and properties. We investigate a spherical harmonics descriptor for shape-based virtual screening. We introduce and validate a partially rotation-invariant three-dimensional molecular shape descriptor based on the norm of spherical harmonics expansion coefficients. Using this molecular representation, we parameterize molecular surfaces, i.e., isosurfaces of spatial molecular property distributions. We validate the shape descriptor in a comprehensive retrospective virtual screening experiment. In a prospective study, we virtually screen a large compound library for cyclooxygenase inhibitors, using a self-organizing map as a pre-filter and the shape descriptor for candidate prioritization. 12 compounds were tested in vitro for direct enzyme inhibition and in a whole blood assay. Active compounds containing a triazole scaffold were identified as direct cyclooxygenase-1 inhibitors. This outcome corroborates the usefulness of spherical harmonics for representation of molecular shape in virtual screening of large compound collections. The combination of pharmacophore and shape-based filtering of screening candidates proved to be a straightforward approach to finding novel bioactive chemotypes with minimal experimental effort.
Semi-Numerical Studies of the Three-Meter Spherical Couette Experiment Utilizing Data Assimilation
Burnett, Sarah; Rojas, Ruben; Perevalov, Artur; Lathrop, Daniel; Ide, Kayo; Schaeffer, Nathanael
2017-11-01
The model of the Earth's magnetic field has been investigated in recent years through experiments and numerical models. At the University of Maryland, experimental studies are implemented in a three-meter spherical Couette device filled with liquid sodium. The inner and outer spheres of this apparatus mimic the planet's inner core and core-mantle boundary, respectively. These experiments incorporate high velocity flows with Reynolds numbers 108 . In spherical Couette geometry, the numerical scheme applied to this work features finite difference methods in the radial direction and pseudospectral spherical harmonic transforms elsewhere. Adding to the numerical model, data assimilation integrates the experimental outer-layer magnetic field measurements. This semi-numerical model can then be compared to the experimental results as well as forecasting magnetic field changes. Data assimilation makes it possible to get estimates of internal motions of the three-meter experiment that would otherwise be intrusive or impossible to obtain in experiments or too computationally expensive with a purely numerical code. If we can provide accurate models of the three-meter device, it is possible to attempt to model the geomagnetic field. We gratefully acknowledge the support of NSF Grant No. EAR1417148 & DGE1322106.
Semi-Numerical Studies of the Three-Meter Spherical Couette Experiment Utilizing Data Assimilation
Burnett, S. C.; Rojas, R.; Perevalov, A.; Lathrop, D. P.
2017-12-01
The model of the Earth's magnetic field has been investigated in recent years through experiments and numerical models. At the University of Maryland, experimental studies are implemented in a three-meter spherical Couette device filled with liquid sodium. The inner and outer spheres of this apparatus mimic the planet's inner core and core-mantle boundary, respectively. These experiments incorporate high velocity flows with Reynolds numbers 108. In spherical Couette geometry, the numerical scheme applied to this work features finite difference methods in the radial direction and pseudospectral spherical harmonic transforms elsewhere [Schaeffer, N. G3 (2013)]. Adding to the numerical model, data assimilation integrates the experimental outer-layer magnetic field measurements. This semi-numerical model can then be compared to the experimental results as well as forecasting magnetic field changes. Data assimilation makes it possible to get estimates of internal motions of the three-meter experiment that would otherwise be intrusive or impossible to obtain in experiments or too computationally expensive with a purely numerical code. If we can provide accurate models of the three-meter device, it is possible to attempt to model the geomagnetic field. We gratefully acknowledge the support of NSF Grant No. EAR1417148 & DGE1322106.
Sensor mount assemblies and sensor assemblies
Miller, David H [Redondo Beach, CA
2012-04-10
Sensor mount assemblies and sensor assemblies are provided. In an embodiment, by way of example only, a sensor mount assembly includes a busbar, a main body, a backing surface, and a first finger. The busbar has a first end and a second end. The main body is overmolded onto the busbar. The backing surface extends radially outwardly relative to the main body. The first finger extends axially from the backing surface, and the first finger has a first end, a second end, and a tooth. The first end of the first finger is disposed on the backing surface, and the tooth is formed on the second end of the first finger.
Physics measurements on WWER-440 diagnostic assemblies
International Nuclear Information System (INIS)
Dach, K.; Jirousek, V.; Kott, J.; Horak, J.; Teren, S.; Nemec, J.
1980-01-01
The aims of physics measurements using diagnostic assemblies are the development of neutron noise diagnostics methods, the improvement of knowledge of the physical properties of the WWER reactor cores, the testing of computer programs, and the specification of nuclear safety criteria and the obtaining of information allowing the optimum nuclear fuel economy. The instrumentation of diagnostic assemblies is briefly described, including miniature fission chambers, SPN detectors and calorimeters. The method of evaluating and experimental testing is shown. (M.S.)
Energy Technology Data Exchange (ETDEWEB)
Shcherbina, M. A., E-mail: shcherbina@ispm.ru; Bakirov, A. V. [Russian Academy of Sciences, Institute of Synthetic Polymer Materials (Russian Federation); Yakunin, A. N. [Karpov Institute of Physical Chemistry (Russian Federation); Percec, V. [University of Pennsylvania (United States); Beginn, U. [Universitaet Osnabrueck, Institut fuer Chemie (Germany); Moeller, M. [Institute for Technical and Macromolecular Chemistry (Germany); Chvalun, S. N. [Russian Academy of Sciences, Institute of Synthetic Polymer Materials (Russian Federation)
2012-03-15
The main stages of the self-assembling of supramolecular ensembles have been revealed by studying different functional wedged macromolecules: polymethacrylates with tapered side chains based on gallic acid, their macromonomers, and salts of 2,3,4- and 3,4,5-tris(dodecyloxy)benzenesulphonic acid. The first stage is the formation of individual supramolecular aggregates (long cylinders or spherical micelles) due to the weak noncovalent interactions of mesogenic groups and the subsequent ordering in these aggregates, which is accompanied by a decrease in the free energy of the system. Supramolecular aggregates, in turn, form 2D or 3D lattices. The shape of supramolecular aggregates and its change with temperature are delicate functions of the mesogen chemical structure; this circumstance makes it possible to rationally design complex self-assembling systems with the ability to respond smartly to external stimuli. X-ray diffraction analysis allows one to study the structure of supramolecular systems with different degrees of order, determine the type of mesophases formed by these systems, and reveal the phase behavior of the material. Particular attention has been paid to the method for reconstruction of electron density distribution from the relative reflection intensity. The application of a suite of experimental methods, including wide- and small-angle X-ray diffraction, molecular modeling, differential scanning calorimetry, and polarization optical microscopy, allows one to establish the relationship between the shape of the structural unit (molecule or molecular aggregate), the nature of the interaction, and the phase behavior of the material.
International Nuclear Information System (INIS)
Shcherbina, M. A.; Bakirov, A. V.; Yakunin, A. N.; Percec, V.; Beginn, U.; Möller, M.; Chvalun, S. N.
2012-01-01
The main stages of the self-assembling of supramolecular ensembles have been revealed by studying different functional wedged macromolecules: polymethacrylates with tapered side chains based on gallic acid, their macromonomers, and salts of 2,3,4- and 3,4,5-tris(dodecyloxy)benzenesulphonic acid. The first stage is the formation of individual supramolecular aggregates (long cylinders or spherical micelles) due to the weak noncovalent interactions of mesogenic groups and the subsequent ordering in these aggregates, which is accompanied by a decrease in the free energy of the system. Supramolecular aggregates, in turn, form 2D or 3D lattices. The shape of supramolecular aggregates and its change with temperature are delicate functions of the mesogen chemical structure; this circumstance makes it possible to rationally design complex self-assembling systems with the ability to respond smartly to external stimuli. X-ray diffraction analysis allows one to study the structure of supramolecular systems with different degrees of order, determine the type of mesophases formed by these systems, and reveal the phase behavior of the material. Particular attention has been paid to the method for reconstruction of electron density distribution from the relative reflection intensity. The application of a suite of experimental methods, including wide- and small-angle X-ray diffraction, molecular modeling, differential scanning calorimetry, and polarization optical microscopy, allows one to establish the relationship between the shape of the structural unit (molecule or molecular aggregate), the nature of the interaction, and the phase behavior of the material.
International Nuclear Information System (INIS)
Sahni, D.C.; Sharma, A.
2000-01-01
The integral form of one-speed, spherically symmetric neutron transport equation with isotropic scattering is considered. Two standard problems are solved using normal mode expansion technique. The expansion coefficients are obtained by solving their singular integral equations. It is shown that these expansion coefficients provide a representation of all spherical harmonics moments of the angular flux as a superposition of Bessel functions. It is seen that large errors occur in the computation of higher moments unless we take certain precautions. The reasons for this phenomenon are explained. They throw some light on the failure of spherical harmonics method in treating spherical geometry problems as observed by Aronsson
In vitro assembly of catalase.
Baureder, Michael; Barane, Elisabeth; Hederstedt, Lars
2014-10-10
Most aerobic organisms contain catalase, which functions to decompose hydrogen peroxide. Typical catalases are structurally complex homo-tetrameric enzymes with one heme prosthetic group buried in each subunit. It is not known how catalase in the cell is assembled from its constituents. The bacterium Enterococcus faecalis cannot synthesize heme but can acquire it from the environment to form a cytoplasmic catalase. We have in E. faecalis monitored production of the enzyme polypeptide (KatA) depending on the availability of heme and used our findings to devise a procedure for the purification of preparative amounts of in vivo-synthesized apocatalase. We show that fully active catalase can be obtained in vitro by incubating isolated apoprotein with hemin. We have characterized features of the assembly process and describe a temperature-trapped hemylated intermediate of the enzyme maturation process. Hemylation of apocatalase does not require auxiliary cell components, but rapid assembly of active enzyme seemingly is assisted in the cell. Our findings provide insight about catalase assembly and offer new experimental possibilities for detailed studies of this process. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.
In Vitro Assembly of Catalase*
Baureder, Michael; Barane, Elisabeth; Hederstedt, Lars
2014-01-01
Most aerobic organisms contain catalase, which functions to decompose hydrogen peroxide. Typical catalases are structurally complex homo-tetrameric enzymes with one heme prosthetic group buried in each subunit. It is not known how catalase in the cell is assembled from its constituents. The bacterium Enterococcus faecalis cannot synthesize heme but can acquire it from the environment to form a cytoplasmic catalase. We have in E. faecalis monitored production of the enzyme polypeptide (KatA) depending on the availability of heme and used our findings to devise a procedure for the purification of preparative amounts of in vivo-synthesized apocatalase. We show that fully active catalase can be obtained in vitro by incubating isolated apoprotein with hemin. We have characterized features of the assembly process and describe a temperature-trapped hemylated intermediate of the enzyme maturation process. Hemylation of apocatalase does not require auxiliary cell components, but rapid assembly of active enzyme seemingly is assisted in the cell. Our findings provide insight about catalase assembly and offer new experimental possibilities for detailed studies of this process. PMID:25148685
Soldering in electronics assembly
Judd, Mike
2013-01-01
Soldering in Electronics Assembly discusses several concerns in soldering of electronic assemblies. The book is comprised of nine chapters that tackle different areas in electronic assembly soldering. Chapter 1 discusses the soldering process itself, while Chapter 2 covers the electronic assemblies. Chapter 3 talks about solders and Chapter 4 deals with flux. The text also tackles the CS and SC soldering process. The cleaning of soldered assemblies, solder quality, and standards and specifications are also discussed. The book will be of great use to professionals who deal with electronic assem
International Nuclear Information System (INIS)
Ip, A.K.; Koyanagi, K.; Tarasuk, W.R.
1976-01-01
A method of fabricating rodded fuels suitable for use in pressure tube type reactors and in pressure vessel type reactors is described. Fuel rods are secured as an inner and an outer sub-assembly, each rod attached between mounting rings secured to the rod ends. The two sub-assemblies are telescoped together and positioned by spaced thimbles located between them to provide precise positioning while permittng differential axial movement between the sub-assemblies. Such sub-assemblies are particularly suited for mounting as bundle strings. The method provides particular advantages in the assembly of annular-section fuel pins, which includes booster fuel containing enriched fuel material. (LL)
International Nuclear Information System (INIS)
Marmonier, Pierre; Mesnage, Bernard; Nervi, J.C.
1975-01-01
This invention refers to fuel assemblies for a liquid metal cooled fast neutron reactor. Each assembly is composed of a hollow vertical casing, of regular polygonal section, containing a bundle of clad pins filled with a fissile or fertile substance. The casing is open at its upper end and has a cylindrical foot at its lower end for positioning the assembly in a housing provided in the horizontal diagrid, on which the core assembly rests. A set of flat bars located on the external surface of the casing enables it to be correctly orientated in its housing among the other core assemblies [fr
Initial value formulation for the spherically symmetric dust solution
International Nuclear Information System (INIS)
Liu, H.
1990-01-01
An initial value formulation for the dust solution with spherical symmetry is given explicitly in which the initial distributions of dust and its velocity on an initial surface are chosen to be the initial data. As special cases, the Friedmann universe, the Schwarzschild solution in comoving coordinates, and a spherically symmetric and radially inhomogeneous cosmological model are derived
Cylindrical and spherical dust-acoustic wave modulations in dusty ...
Indian Academy of Sciences (India)
Abstract. The nonlinear wave modulation of planar and non-planar (cylindrical and spherical) dust-acoustic waves (DAW) propagating in dusty plasmas, in the presence of non-extensive distribu- tions for ions and electrons is investigated. By employing multiple scales technique, a cylindrically and spherically modified ...
Systematic Calibration for a Backpacked Spherical Photogrammetry Imaging System
Rau, J. Y.; Su, B. W.; Hsiao, K. W.; Jhan, J. P.
2016-06-01
A spherical camera can observe the environment for almost 720 degrees' field of view in one shoot, which is useful for augmented reality, environment documentation, or mobile mapping applications. This paper aims to develop a spherical photogrammetry imaging system for the purpose of 3D measurement through a backpacked mobile mapping system (MMS). The used equipment contains a Ladybug-5 spherical camera, a tactical grade positioning and orientation system (POS), i.e. SPAN-CPT, and an odometer, etc. This research aims to directly apply photogrammetric space intersection technique for 3D mapping from a spherical image stereo-pair. For this purpose, several systematic calibration procedures are required, including lens distortion calibration, relative orientation calibration, boresight calibration for direct georeferencing, and spherical image calibration. The lens distortion is serious on the ladybug-5 camera's original 6 images. Meanwhile, for spherical image mosaicking from these original 6 images, we propose the use of their relative orientation and correct their lens distortion at the same time. However, the constructed spherical image still contains systematic error, which will reduce the 3D measurement accuracy. Later for direct georeferencing purpose, we need to establish a ground control field for boresight/lever-arm calibration. Then, we can apply the calibrated parameters to obtain the exterior orientation parameters (EOPs) of all spherical images. In the end, the 3D positioning accuracy after space intersection will be evaluated, including EOPs obtained by structure from motion method.
Stability of transparent spherically symmetric thin shells and wormholes
International Nuclear Information System (INIS)
Ishak, Mustapha; Lake, Kayll
2002-01-01
The stability of transparent spherically symmetric thin shells (and wormholes) to linearized spherically symmetric perturbations about static equilibrium is examined. This work generalizes and systematizes previous studies and explores the consequences of including the cosmological constant. The approach shows how the existence (or not) of a domain wall dominates the landscape of possible equilibrium configurations
Invariants of the spherical sector in conformal mechanics
International Nuclear Information System (INIS)
Hakobyan, Tigran; Nersessian, Armen; Saghatelian, Armen; Lechtenfeld, Olaf
2011-01-01
A direct relation is established between the constants of motion for conformal mechanics and those for its spherical part. In this way, we find the complete set of functionally independent constants of motion for the so-called cuboctahedric Higgs oscillator, which is just the spherical part of the rational A 3 Calogero model (describing four Calogero particles after decoupling their center of mass).
Rapid Prototyping of Electrically Small Spherical Wire Antennas
DEFF Research Database (Denmark)
Kim, Oleksiy S.
2014-01-01
It is shown how modern rapid prototyping technologies can be applied for quick and inexpensive, but still accurate, fabrication of electrically small wire antennas. A well known folded spherical helix antenna and a novel spherical zigzag antenna have been fabricated and tested, exhibiting...
Effect of the spherical Earth on a simple pendulum
Burko, Lior M.
2003-01-01
We consider the period of a simple pendulum in the gravitational field of the spherical Earth. Effectively, gravity is enhanced compared with the often used flat Earth approximation, such that the period of the pendulum is shortened. We discuss the flat Earth approximation, and show when the corrections due to the spherical Earth may be of interest.
Sextupole system for the correction of spherical aberration
Crewe, A.V.; Kopf, D.A.
In an electron beam device in which an electron beam is developed and then focused by a lens to a particular spot, there is provided a means for eliminating spherical aberration. A sextupole electromagnetic lens is positioned between two focusing lenses. The interaction of the sextupole with the beam compensates for spherical aberration. (GHT)
Erosion and damage by hard spherical particles on glass
Slikkerveer, P.J.; Verspui, M.A.; Skerka, G.J.E.
1999-01-01
Solid particle impact of hard spherical particles on glass is of fundamental interest because of the presence of a number of different impact regimes. Understanding the impact of spherical particles is also a step toward modeling the behavior of rounded particles. This paper verifies theoretical
Equilibrium spherically curved two-dimensional Lennard-Jones systems
Voogd, J.M.; Sloot, P.M.A.; van Dantzig, R.
2005-01-01
To learn about basic aspects of nano-scale spherical molecular shells during their formation, spherically curved two-dimensional N-particle Lennard-Jones systems are simulated, studying curvature evolution paths at zero-temperature. For many N-values (N < 800) equilibrium configu- rations are traced
The failure behavior of duplex 316 L steel-TA6V titanium alloy spherical pressure vessels
International Nuclear Information System (INIS)
Miannay, D.
1980-05-01
The purpose of this paper is to compare the experimental residual stresses of spherical vessels made of TA6V alloy which exhibits plasticity before failure in toughness testing and cracked with several configurations, with stresses estimated according to the afore mentioned theories. An internal austenitic 316 L steel is used to prevent 'leak before break' [fr
Acoustic radiation force control: Pulsating spherical carriers.
Rajabi, Majid; Mojahed, Alireza
2018-02-01
The interaction between harmonic plane progressive acoustic beams and a pulsating spherical radiator is studied. The acoustic radiation force function exerted on the spherical body is derived as a function of the incident wave pressure and the monopole vibration characteristics (i.e., amplitude and phase) of the body. Two distinct strategies are presented in order to alter the radiation force effects (i.e., pushing and pulling states) by changing its magnitude and direction. In the first strategy, an incident wave field with known amplitude and phase is considered. It is analytically shown that the zero- radiation force state (i.e., radiation force function cancellation) is achievable for specific pulsation characteristics belong to a frequency-dependent straight line equation in the plane of real-imaginary components (i.e., Nyquist Plane) of prescribed surface displacement. It is illustrated that these characteristic lines divide the mentioned displacement plane into two regions of positive (i.e., pushing) and negative (i.e., pulling) radiation forces. In the second strategy, the zero, negative and positive states of radiation force are obtained through adjusting the incident wave field characteristics (i.e., amplitude and phase) which insonifies the radiator with prescribed pulsation characteristics. It is proved that zero radiation force state occurs for incident wave pressure characteristics belong to specific frequency-dependent circles in Nyquist plane of incident wave pressure. These characteristic circles divide the Nyquist plane into two distinct regions corresponding to positive (out of circles) and negative (in the circles) values of radiation force function. It is analytically shown that the maximum amplitude of negative radiation force is exactly equal to the amplitude of the (positive) radiation force exerted upon the sphere in the passive state, by the same incident field. The developed concepts are much more deepened by considering the required
Theory and applications of spherical microphone array processing
Jarrett, Daniel P; Naylor, Patrick A
2017-01-01
This book presents the signal processing algorithms that have been developed to process the signals acquired by a spherical microphone array. Spherical microphone arrays can be used to capture the sound field in three dimensions and have received significant interest from researchers and audio engineers. Algorithms for spherical array processing are different to corresponding algorithms already known in the literature of linear and planar arrays because the spherical geometry can be exploited to great beneficial effect. The authors aim to advance the field of spherical array processing by helping those new to the field to study it efficiently and from a single source, as well as by offering a way for more experienced researchers and engineers to consolidate their understanding, adding either or both of breadth and depth. The level of the presentation corresponds to graduate studies at MSc and PhD level. This book begins with a presentation of some of the essential mathematical and physical theory relevant to ...
A modular spherical harmonics approach to the neutron transport equation
International Nuclear Information System (INIS)
Inanc, F.; Rohach, A.F.
1989-01-01
A modular nodal method was developed for solving the neutron transport equation in 2-D xy coordinates. The spherical harmonic expansion was used for approximating the second-order even-parity form of the neutron transport equation. The boundary conditions of the spherical harmonics approximation were derived in a form to have forms analogous to the partial currents in the neutron diffusion equation. Relations were developed for generating both the second-order spherical harmonic equations and the boundary conditions in an automated computational algorithm. Nodes using different orders of the spherical harmonics approximation to the transport equation were interfaced through mixed-type boundary conditions. The determination of spherical harmonic orders implemented in the nodes were determined by the scheme in an automated manner. Results of the method compared favorably to benchmark problems. (author)
Meso-scale Modeling of Block Copolymers Self-Assembly in Casting Solutions for Membrane Manufacture
Moreno Chaparro, Nicolas
2016-05-01
Isoporous membranes manufactured from diblock copolymer are successfully produced at laboratory scale under controlled conditions. Because of the complex phenomena involved, membrane preparation requires trial and error methodologies to find the optimal conditions, leading to a considerable demand of resources. Experimental insights demonstrate that the self-assembly of the block copolymers in solution has an effect on the final membrane structure. Nevertheless, the complete understanding of these multi-scale phenomena is elusive. Herein we use the coarse-grained method Dissipative Particle Dynamics to study the self-assembly of block copolymers that are used for the preparation of the membranes. To simulate representative time and length scales, we introduce a framework for model reduction of polymer chain representations for dissipative particle dynamics, which preserves the properties governing the phase equilibria. We reduce the number of degrees of freedom by accounting for the correlation between beads in fine-grained models via power laws and the consistent scaling of the simulation parameters. The coarse-graining models are consistent with the experimental evidence, showing a morphological transition of the aggregates as the polymer concentration and solvent affinity change. We show that hexagonal packing of the micelles can occur in solution within different windows of polymer concentration depending on the solvent affinity. However, the shape and size dispersion of the micelles determine the characteristic arrangement. We describe the order of crew-cut micelles using a rigid-sphere approximation and propose different phase parameters that characterize the emergence of monodisperse-spherical micelles in solution. Additionally, we investigate the effect of blending asymmetric diblock copolymers (AB/AC) over the properties of the membranes. We observe that the co-assembly mechanism localizes the AC molecules at the interface of A and B domains, and induces
Excitation of Alfvenic instabilities in spherical tokamaks
International Nuclear Information System (INIS)
McClements, K.G.; Appel, L.C.; Hole, M.J.; Thyagaraja, A.
2003-01-01
Understanding energetic particle confinement in spherical tokamak (STs) is important for optimising the design of ST power plants, and provides a testbed for theoretical modelling under conditions of strong toroidicity and shaping, and high beta. MHD analysis of some recent beam-heated discharges in the MAST ST indicates that high frequency modes observed in these discharges can be identified as toroidal Alfven Eigenmodes (TAEs) and elliptical Alfven Eigenmodes (EAEs). It is possible that such modes could strongly enhance fusion alpha-particle transport in an ST power plant. Computations of TAE growth rates for one particular MAST discharge, made using the HAGIS guiding centre code and benchmarked against analytical estimates, indicate strong drive by sub-Alfvenic neutral beam ions. HAGIS computations using higher mode amplitudes than those observed indicate that whereas co-passing beam ions provide the bulk of he TAE drive, counter-passing ions provide the dominant component of TAE-induced particle losses. Axisymmetric Alfvenic mode activity has been detected during ohmic discharges in MAST. These observations are shown by computational modelling to be consistent with the excitation of global Alfven Eigenmodes (GAEs) with n=0 and low m, driven impulsively by low frequency MHD. (author)
Plasmonic and silicon spherical nanoparticle antireflective coatings
Baryshnikova, K. V.; Petrov, M. I.; Babicheva, V. E.; Belov, P. A.
2016-03-01
Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes.
The spheric tokamak programme at Culham
International Nuclear Information System (INIS)
Sykes, A.
1999-01-01
The Spherical Tokamak (ST) is the low aspect ratio limit of the conventional tokamak, and appears to offer attractive physics properties in a simpler device. The START (Small Tight Aspect Ratio Tokamak) experiment provided the world's first demonstration of the properties of hot plasmas in an ST configuration, and was operational at Culham from January 1991 to March 1998, obtaining plasma current of up to 300 kA and pulse durations of ∼ 50 ms. Its successor, MAST is scheduled to obtain first plasma in Autumn 1998 and is a purpose built, high vacuum machine designed to have a tenfold increase in plasma volume with plasma currents up to 2 MA. Current drive and heating will be by a combination of induction-compression as on START, a high-performance central solenoid, 1.5 MW ECRH and 5 MW of Neutral Beam Injection. The promising results from START are reviewed, and the many challenges posed for the next generation of purpose-built STs (such as MAST) are described. (author)
Spherical images and inextensible curved folding
Seffen, Keith A.
2018-02-01
In their study, Duncan and Duncan [Proc. R. Soc. London A 383, 191 (1982), 10.1098/rspa.1982.0126] calculate the shape of an inextensible surface folded in two about a general curve. They find the analytical relationships between pairs of generators linked across the fold curve, the shape of the original path, and the fold angle variation along it. They present two special cases of generator layouts for which the fold angle is uniform or the folded curve remains planar, for simplifying practical folding in sheet-metal processes. We verify their special cases by a graphical treatment according to a method of Gauss. We replace the fold curve by a piecewise linear path, which connects vertices of intersecting pairs of hinge lines. Inspired by the d-cone analysis by Farmer and Calladine [Int. J. Mech. Sci. 47, 509 (2005), 10.1016/j.ijmecsci.2005.02.013], we construct the spherical images for developable folding of successive vertices: the operating conditions of the special cases in Duncan and Duncan are then revealed straightforwardly by the geometric relationships between the images. Our approach may be used to synthesize folding patterns for novel deployable and shape-changing surfaces without need of complex calculation.
Spherical dust collapse in higher dimensions
International Nuclear Information System (INIS)
Goswami, Rituparno; Joshi, Pankaj S.
2004-01-01
We consider here whether it is possible to recover cosmic censorship when a transition is made to higher-dimensional spacetimes, by studying the spherically symmetric dust collapse in an arbitrary higher spacetime dimension. It is pointed out that if only black holes are to result as the end state of a continual gravitational collapse, several conditions must be imposed on the collapsing configuration, some of which may appear to be restrictive, and we need to study carefully if these can be suitably motivated physically in a realistic collapse scenario. It would appear, that, in a generic higher-dimensional dust collapse, both black holes and naked singularities would develop as end states as indicated by the results here. The mathematical approach developed here generalizes and unifies the earlier available results on higher-dimensional dust collapse as we point out. Further, the dependence of black hole or naked singularity end states as collapse outcomes on the nature of the initial data from which the collapse develops is brought out explicitly and in a transparent manner as we show here. Our method also allows us to consider here in some detail the genericity and stability aspects related to the occurrence of naked singularities in gravitational collapse
Scaling laws for spherical pinch experiments
International Nuclear Information System (INIS)
Singh, D.P.; Palleschi, V.; Vaselli, M.
1991-01-01
In spherical pinch (SP) experiments, the plasma heated at the center of a cell to reach ignition temperature is confined by imploding shock waves for a time long enough to satisfy the Lawson criterion for plasma fusion. In earlier theoretical studies, the expansion of the central plasma either is neglected or is assumed to be radially uniform. The energy is considered to be deposited instantaneously at the center of the cell and the nonlinear heat conduction equation is solved to study the temporal evolution of the central plasma. Incorporating the ignition condition for the average temperature of the expanding fireball, and its confinement by imploding convergent shock waves, which may be fired from the periphery of the cell with some time delay, the scaling laws for satisfying the Lawson criterion are investigated in detail. The relevant calculations indicate that the cumulative effects of the convergent shock waves in the vicinity of the center of the cell play an important role in these scaling laws. (author)
Spherical radial basis functions, theory and applications
Hubbert, Simon; Morton, Tanya M
2015-01-01
This book is the first to be devoted to the theory and applications of spherical (radial) basis functions (SBFs), which is rapidly emerging as one of the most promising techniques for solving problems where approximations are needed on the surface of a sphere. The aim of the book is to provide enough theoretical and practical details for the reader to be able to implement the SBF methods to solve real world problems. The authors stress the close connection between the theory of SBFs and that of the more well-known family of radial basis functions (RBFs), which are well-established tools for solving approximation theory problems on more general domains. The unique solvability of the SBF interpolation method for data fitting problems is established and an in-depth investigation of its accuracy is provided. Two chapters are devoted to partial differential equations (PDEs). One deals with the practical implementation of an SBF-based solution to an elliptic PDE and another which describes an SBF approach for solvi...
Failure internal pressure of spherical steel containments
International Nuclear Information System (INIS)
Sanchez Sarmiento, G.
1985-01-01
An application of the British CEGB's R6 Failure Assessment Approach to the determination of failure internal pressure of nuclear power plant spherical steel containments is presented. The presence of hypothetical cracks both in the base metal and in the welding material of the containment, with geometrical idealizations according to the ASME Boiler and Pressure Vessel Code (Section XI), was taken into account in order to analyze the sensitivity of the failure assessment with the values of the material fracture properties. Calculations of the elastoplastic collapse load have been performed by means of the Finite Element System SAMCEF. The clean axisymmetric shell (neglecting the influence of nozzles and minor irregularities) and two major penetrations (personnel and emergency locks) have been taken separately into account. Large-strain elastoplastic behaviour of the material was considered in the Code, using lower bounds of true stress-true strain relations obtained by testing a collection of tensile specimens. Assuming the presence of cracks in non-perturbed regions, the reserve factor for test pressure and the failure internal pressure have been determined as a function of the flaw depth. (orig.)
Synchrotron radiation from spherically accreting black holes
International Nuclear Information System (INIS)
Ipser, J.R.; Price, R.H.
1982-01-01
Spherical accretion onto a Schwartzchild black hole, of gas with frozen-in magnetic field, is studied numerically and analytically for a range of hole masses and accretion rates in which synchrotron emission is the dominant radiative mechanism. At small radii the equipartition of magnetic, kinetic, and gravitational energy is assumed to apply, and the gas is heated by dissipation of infalling magnetic energy, turbulent energy, etc. The models can be classified into three types: (a) synchrotron cooling negligible, (b) synchrotron cooling important but synchrotron self-absorption negligible, (c) synchrotron cooling and self-absorption important. In the first case gas temperatures become very high near the horizon but luminosity efficiencies (luminosity/mass-energy accretion rate) are low. In cases (b) and (c) the gas flow near the horizon is essentially isothermal and luminosity efficiencies are fairly high. The analysis and results for the isothermal cases (b) and (c) are valid only for moderate dissipative heating and synchrotron self-absorption. If self-absorption is very strong or if dissipated energy is comparable to infall energy, Comptonization effects, not included in the analysis, become important
Spherical Process Models for Global Spatial Statistics
Jeong, Jaehong
2017-11-28
Statistical models used in geophysical, environmental, and climate science applications must reflect the curvature of the spatial domain in global data. Over the past few decades, statisticians have developed covariance models that capture the spatial and temporal behavior of these global data sets. Though the geodesic distance is the most natural metric for measuring distance on the surface of a sphere, mathematical limitations have compelled statisticians to use the chordal distance to compute the covariance matrix in many applications instead, which may cause physically unrealistic distortions. Therefore, covariance functions directly defined on a sphere using the geodesic distance are needed. We discuss the issues that arise when dealing with spherical data sets on a global scale and provide references to recent literature. We review the current approaches to building process models on spheres, including the differential operator, the stochastic partial differential equation, the kernel convolution, and the deformation approaches. We illustrate realizations obtained from Gaussian processes with different covariance structures and the use of isotropic and nonstationary covariance models through deformations and geographical indicators for global surface temperature data. To assess the suitability of each method, we compare their log-likelihood values and prediction scores, and we end with a discussion of related research problems.
Painleve-Gullstrand synchronizations in spherical symmetry
International Nuclear Information System (INIS)
Herrero, Alicia; Morales-Lladosa, Juan Antonio
2010-01-01
A Painleve-Gullstrand synchronization is a slicing of the spacetime by a family of flat space-like 3-surfaces. For spherically symmetric spacetimes, we show that a Painleve-Gullstrand synchronization only exists in the region where (dr) 2 ≤ 1, r being the curvature radius of the isometry group orbits (2-spheres). This condition states that the Misner-Sharp gravitational energy of these 2-spheres is not negative and has an intrinsic meaning in terms of the norm of the mean extrinsic curvature vector. It also provides an algebraic inequality involving the Weyl curvature scalar and the Ricci eigenvalues. We prove that the energy and momentum densities associated with the Weinberg complex of a Painleve-Gullstrand slice vanish in these curvature coordinates, and we give a new interpretation of these slices by using semi-metric Newtonian connections. It is also outlined that, by solving the vacuum Einstein's equations in a coordinate system adapted to a Painleve-Gullstrand synchronization, the Schwarzschild solution is directly obtained in a whole coordinate domain that includes the horizon and both its interior and exterior regions.
Optimization of magnetic field system for glass spherical tokamak GLAST-III
International Nuclear Information System (INIS)
Ahmad, Zahoor; Ahmad, S; Naveed, M A; Deeba, F; Javeed, M Aqib; Batool, S; Hussain, S; Vorobyov, G M
2017-01-01
GLAST-III (Glass Spherical Tokamak) is a spherical tokamak with aspect ratio A = 2. The mapping of its magnetic system is performed to optimize the GLAST-III tokamak for plasma initiation using a Hall probe. Magnetic field from toroidal coils shows 1/ R dependence which is typical with spherical tokamaks. Toroidal field (TF) coils can produce 875 Gauss field, an essential requirement for electron cyclotron resonance assisted discharge. The central solenoid (CS) of GLAST-III is an air core solenoid and requires compensation coils to reduce unnecessary magnetic flux inside the vessel region. The vertical component of magnetic field from the CS in the vacuum vessel region is reduced to 1.15 Gauss kA −1 with the help of a differential loop. The CS of GLAST can produce flux change up to 68 mVs. Theoretical and experimental results are compared for the current waveform of TF coils using a combination of fast and slow capacitor banks. Also the magnetic field produced by poloidal field (PF) coils is compared with theoretically predicted values. It is found that calculated results are in good agreement with experimental measurement. Consequently magnetic field measurements are validated. A tokamak discharge with 2 kA plasma current and pulse length 1 ms is successfully produced using different sets of coils. (paper)
Dissolution of spherical cap CO2 bubbles attached to flat surfaces in air-saturated water
Peñas, Pablo; Parrales, Miguel A.; Rodriguez-Rodriguez, Javier
2014-11-01
Bubbles attached to flat surfaces immersed in quiescent liquid environments often display a spherical cap (SC) shape. Their dissolution is a phenomenon commonly observed experimentally. Modelling these bubbles as fully spherical may lead to an inaccurate estimate of the bubble dissolution rate. We develop a theoretical model for the diffusion-driven dissolution or growth of such multi-component SC gas bubbles under constant pressure and temperature conditions. Provided the contact angle of the bubble with the surface is large, the concentration gradients in the liquid may be approximated as spherically symmetric. The area available for mass transfer depends on the instantaneous bubble contact angle, whose dynamics is computed from the adhesion hysteresis model [Hong et al., Langmuir, vol. 27, 6890-6896 (2011)]. Numerical simulations and experimental measurements on the dissolution of SC CO2 bubbles immersed in air-saturated water support the validity of our model. We verify that contact line pinning slows down the dissolution rate, and the fact that any bubble immersed in a saturated gas-liquid solution eventually attains a final equilibrium size. Funded by the Spanish Ministry of Economy and Competitiveness through Grant DPI2011-28356-C03-0.
Contact of a spherical probe with a stretched rubber substrate
Frétigny, Christian; Chateauminois, Antoine
2017-07-01
We report on a theoretical and experimental investigation of the normal contact of stretched neo-Hookean substrates with rigid spherical probes. Starting from a published formulation of surface Green's function for incremental displacements on a prestretched, neo-Hookean, substrate [J. Mech. Phys. Solids 56, 2957 (2008), 10.1016/j.jmps.2008.07.002], a model is derived for both adhesive and nonadhesive contacts. The shape of the elliptical contact area together with the contact load and the contact stiffness are predicted as a function of the in-plane stretch ratios λx and λy of the substrate. The validity of this model is assessed by contact experiments carried out using an uniaxally stretched silicone rubber. For stretch ratio below about 1.25, a good agreement is observed between theory and experiments. Above this threshold, some deviations from the theoretical predictions are induced as a result of the departure of the mechanical response of the silicone rubber from the neo-Hokeean description embedded in the model.
Study on wall recycling behaviour in CPD spherical tokamak
International Nuclear Information System (INIS)
Bhattacharyay, R.; Zushi, H.; Hirooka, Y.; Sakamoto, M.; Yoshinaga, T.; Okamoto, K.; Kawasaki, S.; Hanada, K.; Sato, K.N.; Nakamura, K.; Idei, H.; Ryoukai, T.; Nakashima, H.; Higashijima, A.
2008-01-01
Experiments to study wall recycling behaviour have been performed in the small spherical tokamak compact plasma-wall interaction experimental device (CPD) from the viewpoint of global as well as local plasma wall interaction condition. Electron cyclotron resonance (ECR) plasma of typically ∼50 to 400 ms duration is produced using ∼40 to 80 kW RF power. In order to study the global wall recycling behaviour, pressure measurements are carried out just before and after the ECR plasma in the absence of any external pumping. The recycling behaviour is found to change from release to pumping beyond a certain level of pressure value which is again found to be a function of shot history. The real-time local wall behaviour is studied in similar RF plasma using a rotating tungsten limiter, actively coated with lithium. Measurement of H α light intensity in front of the rotating surface has indicated a clear reduction (∼10%) in the steady-state hydrogen recycling with continuous Li gettering of several minutes
Nonlocal neoclassical transport in tokamak and spherical torus experiments
International Nuclear Information System (INIS)
Wang, W. X.; Rewoldt, G.; Tang, W. M.; Hinton, F. L.; Manickam, J.; Zakharov, L. E.; White, R. B.; Kaye, S.
2006-01-01
Large ion orbits can produce nonlocal neoclassical effects on ion heat transport, the ambipolar radial electric field, and the bootstrap current in realistic toroidal plasmas. Using a global δf particle simulation, it is found that the conventional local, linear gradient-flux relation is broken for the ion thermal transport near the magnetic axis. With regard to the transport level, it is found that details of the ion temperature profile determine whether the transport is higher or lower when compared with the predictions of standard neoclassical theory. Particularly, this nonlocal feature is suggested to exist in the National Spherical Torus Experiment (NSTX) [M. Ono, S. M. Kaye, Y.-K. M. Peng et al., Nucl. Fusion 40, 557 (2000)], being consistent with NSTX experimental evidence. It is also shown that a large ion temperature gradient can increase the bootstrap current. When the plasma rotation is taken into account, the toroidal rotation gradient can drive an additional parallel flow for the ions and then additional bootstrap current, either positive or negative, depending on the gradient direction. Compared with the carbon radial force balance estimate for the neoclassical poloidal flow, our nonlocal simulation predicts a significantly deeper radial electric field well at the location of an internal transport barrier of an NSTX discharge
Nonlinear simulation of edge-localized mode in spherical tokamak
International Nuclear Information System (INIS)
Mizuguchi, N.; Hayashi, T.; Nakajima, N.; Khan, R.
2006-10-01
A numerical modeling for the dynamics of an edge-localized mode (ELM) crash in the spherical tokamak is proposed with a consecutive scenario which is initiated by the spontaneous growth of the ballooning mode instability by means of a three-dimensional nonlinear magnetohydrodynamic simulation. The simulation result shows a two-step relaxation process which is induced by the intermediate-n ballooning instability followed by the m/n=1/1 internal kink mode, where m and n represent the poloidal and toroidal mode numbers, respectively. By comparing with the experimental observations, we have found that the simulation result can reproduce several characteristic features of the so-called type-I ELM in an appropriate time scale: (1) relation to the ballooning instability, (2) intermediate-n precursors, (3) low-n structure on the crash, (4) formation and separation of the filament, and (5) considerable amount of loss of plasma. Furthermore, the model is verified by examining the effect of diamagnetic stabilization and comparing the nonlinear behavior with that of the peeling modes. The ion diamagnetic drift terms are found to stabilize some specific components linearly; nevertheless they are not so effective in the nonlinear dynamics such as the filament formation and the amount of loss. For the peeling mode case, no prominent filament structure is formed in contrast to the ballooning case. (author)
Extreme super-resolution using the spherical geodesic waveguide
Miñano, Juan Carlos; González, Juan Carlos; Benítez, Pablo; Grabovičkić, Dejan
2012-06-01
Leonhardt demonstrated (2009) that the 2D Maxwell Fish Eye lens (MFE) can focus perfectly 2D Helmholtz waves of arbitrary frequency, i.e., it can transport perfectly an outward (monopole) 2D Helmholtz wave field, generated by a point source, towards a "perfect point drain" located at the corresponding image point. Moreover, a prototype with λ/5 super-resolution (SR) property for one microwave frequency has been manufactured and tested (Ma et al, 2010). Although this prototype has been loaded with an impedance different from the "perfect point drain", it has shown super-resolution property. However, neither software simulations nor experimental measurements for a broad band of frequencies have yet been reported. Here we present steady state simulations for two cases, using perfect drain as suggested by Leonhardt and without perfect drain as in the prototype. All the simulations have been done using a device equivalent to the MFE, called the Spherical Geodesic Waveguide (SGW). The results show the super-resolution up to λ/3000, for the system loaded with the perfect drain, and up to λ /500 for a not perfect load. In both cases super-resolution only happens for discrete number of frequencies. Out of these frequencies, the SGW does not show super-resolution in the analysis carried out.