ARGO, 1-D Neutron Diffusion in Slab, Cylindrical, Spherical Geometry from JAERI Fast-Set, ABBN, RCBN
International Nuclear Information System (INIS)
Ikawa, Koji
1971-01-01
1 - Nature of physical problem solved: ARGO is a one-dimensional (slab, cylinder or sphere), multigroup diffusion code for use in fast reactor criticality and kinetic parameter analysis. Three cross section sets, i.e., JAERI-Fast-Set, ABBN-Set and RCBN-Set, of 25 groups are prepared for the code as its library tapes. 2 - Method of solution: Eigenvalues are computed by ordinary source-iteration techniques with ordinary acceleration methods for convergence. 3 - Restrictions on the complexity of the problem: Sphere geometry
Power deposition in a cylindrical geometry using B-10 coatings
International Nuclear Information System (INIS)
Chung, A.K.; Prelas, M.A.
1983-01-01
The transport of charged particles produced by 10 B (n, α) Li and 235 U (n, νn) ff nuclear reactions in a two region cylindrical geometry is predicted. We employed a mean-range straight-flight approximation to calculate the power deposition by the charged particles in a gaseous medium. Our model demonstrated some features in a cylindrical experiment which were suspected but not proven. In the common slab model used by Guyot et al 1 and Romero 2 , the spatial distribution of power deposition is much flatter than it would be in a cylindrical model. A steeper gradient in the power deposition is expected in a cylindrical geometry than in a slab geometry. We also found that for a standard thickness of Boron-10 coating (1.73 μm) used in NPLs, the expected efficiency of a cylindrical geometry (7.5%) is much lower than the 12% efficiency predicted by the slab model. Indeed the use of slab geometry in modeling current NPL experimental devices is not accurate
Convection in Slab and Spheroidal Geometries
Porter, David H.; Woodward, Paul R.; Jacobs, Michael L.
2000-01-01
Three-dimensional numerical simulations of compressible turbulent thermally driven convection, in both slab and spheroidal geometries, are reviewed and analyzed in terms of velocity spectra and mixing-length theory. The same ideal gas model is used in both geometries, and resulting flows are compared. The piecewise-parabolic method (PPM), with either thermal conductivity or photospheric boundary conditions, is used to solve the fluid equations of motion. Fluid motions in both geometries exhibit a Kolmogorov-like k(sup -5/3) range in their velocity spectra. The longest wavelength modes are energetically dominant in both geometries, typically leading to one convection cell dominating the flow. In spheroidal geometry, a dipolar flow dominates the largest scale convective motions. Downflows are intensely turbulent and up drafts are relatively laminar in both geometries. In slab geometry, correlations between temperature and velocity fluctuations, which lead to the enthalpy flux, are fairly independent of depth. In spheroidal geometry this same correlation increases linearly with radius over the inner 70 percent by radius, in which the local pressure scale heights are a sizable fraction of the radius. The effects from the impenetrable boundary conditions in the slab geometry models are confused with the effects from non-local convection. In spheroidal geometry nonlocal effects, due to coherent plumes, are seen as far as several pressure scale heights from the lower boundary and are clearly distinguishable from boundary effects.
Microinstabilities in a radially contracting inhomogeneous cylindrical plasma slab
International Nuclear Information System (INIS)
Deutsch, R.; Kaeppeler, H.J.
1980-07-01
In order to study the development of microinstabilities in a collapsing cylindrical plasma sheath, corresponding to the situations in a z-pinch or a plasma focus, the dispersion relation for electromagnetic perturbations is derived with the aid of a newly established slab-model for an inhomogeneous, radially contracting plasma. In contrast to previously used slab-models, the orientation of the electric field is in direction of the cylinder axis and the azimuthal magnetic field is induced by the current flowing through the cylindrical plasma slab. The Vlasov equation is used together with the Krook collision term in order to include the influence of collisions. The results of this theory presented in this report will be used to calculate the growth of drift instabilities in the compression phase of a plasma focus, and shall serve as a basis for further development of a more general dispersion relation including runaway-effects. (orig.)
Unstable drift eigenmode in slab geometry
International Nuclear Information System (INIS)
Tsotsonis, S.; Hirose, A.
1986-01-01
The unstable Pearlstein-Berk mode of drift waves in plane, sheared slab geometry has later been shown to be stable when electron Landau resonance is rigorously treated. Based on the variational method previously developed the authors have found that in addition to the absolutely stable Pearlstein-Berk mode, there exists an absolutely unstable eigenfunction characterized by ω ≤ ω/sub chemical bonde/, and weak ''radial'' dependence. Also, the growth rate, only weakly depends on the magnetic shear and ion/electron temperature ratio
Cylindrical geometry for proportional and drift chambers
International Nuclear Information System (INIS)
Sadoulet, B.
1975-06-01
For experiments performed around storage rings such as e + e - rings or the ISR pp rings, cylindrical wire chambers are very attractive. They surround the beam pipe completely without any dead region in the azimuth, and fit well with the geometry of events where particles are more or less spherically produced. Unfortunately, cylindrical proportional or drift chambers are difficult to make. Problems are discussed and two approaches to fabricating the cathodes are discussed. (WHK)
Escape and transmission probabilities in cylindrical geometry
International Nuclear Information System (INIS)
Bjerke, M.A.
1980-01-01
An improved technique for the generation of escape and transmission probabilities in cylindrical geometry was applied to the existing resonance cross section processing code ROLAIDS. The algorithm of Hwang and Toppel, [ANL-FRA-TM-118] (with modifications) was employed. The probabilities generated were found to be as accurate as those given by the method previously applied in ROLAIDS, while requiring much less computer core storage and CPU time
The heterogeneous response method in slab geometry
International Nuclear Information System (INIS)
Villarino, E.A.; Stamm'ler, R.J.J.
1984-01-01
The heterogeneous response method (HRM) has been developed to calculate the multigroup flux in a heterogeneous system, e.g. a fuel assembly, without having to resort to dubious homogenization recipes. Here, the method is described in slab geometry in a manner that facilitates its computerization. By dividing the system into subsystems or nodes, say pin cells, two levels of calculation are created, which define a set of local problems and a global problem, respectively. In the local problem, collision probabilities are used to obtain for a node in vacuum, its response fluxes caused by sources and in-currents. They preserve the heterogeneous character of the node. In the global problem, the nodes are coupled by cosine currents. A suitable transformation reduces the number of two unknown currents per interface to one unknown per node, its total transmitted in-current. The global equation system thus becomes a set of three-point relations, which can be solved efficiently. In cases typical of fuel-assembly situations, the HRM produces fluxes that compare very well with the direct solution of the entire system by collision probabilities, though at a fraction of the computer cost. Extension of the method to 2- and 3-D systems is discussed. (author)
The analytic nodal method in cylindrical geometry
International Nuclear Information System (INIS)
Prinsloo, Rian H.; Tomasevic, Djordje I.
2008-01-01
Nodal diffusion methods have been used extensively in nuclear reactor calculations, specifically for their performance advantage, but also for their superior accuracy. More specifically, the Analytic Nodal Method (ANM), utilising the transverse integration principle, has been applied to numerous reactor problems with much success. In this work, a nodal diffusion method is developed for cylindrical geometry. Application of this method to three-dimensional (3D) cylindrical geometry has never been satisfactorily addressed and we propose a solution which entails the use of conformal mapping. A set of 1D-equations with an adjusted, geometrically dependent, inhomogeneous source, is obtained. This work describes the development of the method and associated test code, as well as its application to realistic reactor problems. Numerical results are given for the PBMR-400 MW benchmark problem, as well as for a 'cylindrisized' version of the well-known 3D LWR IAEA benchmark. Results highlight the improved accuracy and performance over finite-difference core solutions and investigate the applicability of nodal methods to 3D PBMR type problems. Results indicate that cylindrical nodal methods definitely have a place within PBMR applications, yielding performance advantage factors of 10 and 20 for 2D and 3D calculations, respectively, and advantage factors of the order of 1000 in the case of the LWR problem
Waves in inhomogeneous plasma of cylindrical geometry
International Nuclear Information System (INIS)
Rebut, P.H.
1966-01-01
The conductivity tensor of a hot and inhomogeneous plasma has been calculated for a cylindrical geometry using Vlasov equations. The method used consists in a perturbation method involving the first integrals of the unperturbed movement. The conductivity tensor will be particularly useful for dealing with stability problems. In the case of a cold plasma the wave equation giving the electric fields as a function of the radius is obtained. This equation shows the existence of resonant layers which lead to an absorption analogous to the Landau absorption in a hot plasma. (author) [fr
Magnethohydrodynamic surface and body waves in rectangular and cylindrical geometries
International Nuclear Information System (INIS)
Donnelly, I.J.
1982-03-01
Low frequency magnetohydrodynamic (MHD) waves are studied in both rectangular slab and cylindrical geometry cavities containing low β plasmas. The plasma density distribution is modelled by an inner region of constant density surrounded by an outer region of lower density and a conducting boundary. The wave frequencies and fields are obtained as functions of the density distribution and the wavenumber components k(parall) and k(perp). The lowest frequency wave mode is a surface wave in which the wave fields decrease in magnitude with distance from the interface between the two plasma densities. It has the properties of a shear wave when k(perp)/k(parall) is either small or large but is compressive when k(perp) is approximately equal to k(parall). The surface wave does not exist when k(perp) = 0. Higher frequency modes have the properties of fast magnetosonic waves, at least in the inner density region
Slab2 - Updated Subduction Zone Geometries and Modeling Tools
Moore, G.; Hayes, G. P.; Portner, D. E.; Furtney, M.; Flamme, H. E.; Hearne, M. G.
2017-12-01
The U.S. Geological Survey database of global subduction zone geometries (Slab1.0), is a highly utilized dataset that has been applied to a wide range of geophysical problems. In 2017, these models have been improved and expanded upon as part of the Slab2 modeling effort. With a new data driven approach that can be applied to a broader range of tectonic settings and geophysical data sets, we have generated a model set that will serve as a more comprehensive, reliable, and reproducible resource for three-dimensional slab geometries at all of the world's convergent margins. The newly developed framework of Slab2 is guided by: (1) a large integrated dataset, consisting of a variety of geophysical sources (e.g., earthquake hypocenters, moment tensors, active-source seismic survey images of the shallow slab, tomography models, receiver functions, bathymetry, trench ages, and sediment thickness information); (2) a dynamic filtering scheme aimed at constraining incorporated seismicity to only slab related events; (3) a 3-D data interpolation approach which captures both high resolution shallow geometries and instances of slab rollback and overlap at depth; and (4) an algorithm which incorporates uncertainties of contributing datasets to identify the most probable surface depth over the extent of each subduction zone. Further layers will also be added to the base geometry dataset, such as historic moment release, earthquake tectonic providence, and interface coupling. Along with access to several queryable data formats, all components have been wrapped into an open source library in Python, such that suites of updated models can be released as further data becomes available. This presentation will discuss the extent of Slab2 development, as well as the current availability of the model and modeling tools.
Parametric excitation of drift waves in a sheared slab geometry
International Nuclear Information System (INIS)
Vranjes, J.; Weiland, J.
1992-01-01
The threshold for parametric excitation of drift waves in a sheared slab geometry is calculated for a pump wave that is a standing wave along the magnetic field, using the Hasegawa-Mima nonlinearity. The shear damping is counteracted by the parametric coupling and the eigenvalue problem is solved analytically using Taylor's strong coupling approximation. (au)
Neutron flux in a periodical slab geometry (1960)
International Nuclear Information System (INIS)
Lamare, J. de; Mathelot, P.; Cadhilac, M.
1960-01-01
In the present report, we explain an original method to perform exact calculations of neutron flux in either of two geometries: a slab surrounded by an infinite multiplying medium or a periodical, one dimensional array of two different media. (author) [fr
Numerical determination of transmission probabilities in cylindrical geometry
International Nuclear Information System (INIS)
Queiroz Bogado Leite, S. de.
1989-11-01
Efficient methods for numerical calculation of transmission probabilities in cylindrical geometry are presented. Relative errors of the order of 10 -5 or smaller are obtained using analytical solutions and low order quadrature integration schemes. (author) [pt
DIGA/NSL new calculational model in slab geometry
International Nuclear Information System (INIS)
Makai, M.; Gado, J.; Kereszturi, A.
1987-04-01
A new calculational model is presented based on a modified finite-difference algorithm, in which the coefficients are determined by means of the so-called gamma matrices. The DIGA program determines the gamma matrices and the NSL program realizes the modified finite difference model. Both programs assume slab cell geometry, DIGA assumes 2 energy groups and 3 diffusive regions. The DIGA/NSL programs serve to study the new calculational model. (author)
Multi-Group Reductions of LTE Air Plasma Radiative Transfer in Cylindrical Geometries
Scoggins, James; Magin, Thierry Edouard Bertran; Wray, Alan; Mansour, Nagi N.
2013-01-01
Air plasma radiation in Local Thermodynamic Equilibrium (LTE) within cylindrical geometries is studied with an application towards modeling the radiative transfer inside arc-constrictors, a central component of constricted-arc arc jets. A detailed database of spectral absorption coefficients for LTE air is formulated using the NEQAIR code developed at NASA Ames Research Center. The database stores calculated absorption coefficients for 1,051,755 wavelengths between 0.04 µm and 200 µm over a wide temperature (500K to 15 000K) and pressure (0.1 atm to 10.0 atm) range. The multi-group method for spectral reduction is studied by generating a range of reductions including pure binning and banding reductions from the detailed absorption coefficient database. The accuracy of each reduction is compared to line-by-line calculations for cylindrical temperature profiles resembling typical profiles found in arc-constrictors. It is found that a reduction of only 1000 groups is sufficient to accurately model the LTE air radiation over a large temperature and pressure range. In addition to the reduction comparison, the cylindrical-slab formulation is compared with the finite-volume method for the numerical integration of the radiative flux inside cylinders with varying length. It is determined that cylindrical-slabs can be used to accurately model most arc-constrictors due to their high length to radius ratios.
Particle Creation in Oscillating Cavities with Cubic and Cylindrical Geometry
Setare, M. R.; Dinani, H. T.
2008-04-01
In the present paper we study the creation of massless scalar particles from the quantum vacuum due to the dynamical Casimir effect by oscillating cavities with cubic and cylindrical geometry. To the first order of the amplitude we derive the expressions for the number of the created particles.
Slab geometry spatial discretization schemes with infinite-order convergence
International Nuclear Information System (INIS)
Adams, M.L.; Martin, W.R.
1985-01-01
Spatial discretization schemes for the slab geometry discrete ordinates transport equation have received considerable attention in the past several years, with particular interest shown in developing methods that are more computationally efficient that standard schemes. Here the authors apply to the discrete ordinates equations a spectral method that is significantly more efficient than previously proposed schemes for high-accuracy calculations of homogeneous problems. This is a direct consequence of the exponential (infinite-order) convergence of spectral methods for problems with every smooth solutions. For heterogeneous problems where smooth solutions do not exist and exponential convergence is not observed with spectral methods, a spectral element method is proposed which does exhibit exponential convergence
A nonlinear resistive MHD-code in cylindrical geometry
International Nuclear Information System (INIS)
Jakoby, A.
1987-11-01
A computer code has been developed which solves the full compressible resistive magnetohydrodynamic (MHD) equations in cylindrical geometry. The variables are expanded in Fourier series in the poloidal and axial directions while finite differences are used in the radial direction. The time advance is accomplished by using a semi-implicit predictor-corrector-scheme. Applications to the ideal m=1 ideal kink saturation in the nonlinear regime and the subsequent decay of the singular current layer due to resistivity are presented. (orig.)
Attenuation correction factors for cylindrical, disc and box geometry
International Nuclear Information System (INIS)
Agarwal, Chhavi; Poi, Sanhita; Mhatre, Amol; Goswami, A.; Gathibandhe, M.
2009-01-01
In the present study, attenuation correction factors have been experimentally determined for samples having cylindrical, disc and box geometry and compared with the attenuation correction factors calculated by Hybrid Monte Carlo (HMC) method [ C. Agarwal, S. Poi, A. Goswami, M. Gathibandhe, R.A. Agrawal, Nucl. Instr. and. Meth. A 597 (2008) 198] and with the near-field and far-field formulations available in literature. It has been observed that the near-field formulae, although said to be applicable at close sample-detector geometry, does not work at very close sample-detector configuration. The advantage of the HMC method is that it is found to be valid for all sample-detector geometries.
Three-dimensional simulations of magnetic reconnection in slab geometry
International Nuclear Information System (INIS)
Onofri, M.; Primavera, L.; Malara, F.; Veltri, P.
2004-01-01
Magnetic reconnection in an incompressible plasma in three-dimensional slab geometry has been studied through magnetohydrodynamics numerical simulations. Particular attention has been paid to the case in which several unstable modes that correspond to resonant surfaces in different positions of the simulation domain, are excited at the beginning of the simulation. The dynamical evolution of such a system leads to a behavior different than what is expected from the linear theory. In particular the effects of the equilibrium field dissipation and the fact that several resonant surfaces are initially excited both concur in modifying the initial growth rates of the instability. In the nonlinear phase two basic phenomena are observed: first, the rapid transfer of energy to large wave numbers, corresponding to a direct cascade of the energy in the spectrum, which approaches, with increasing time, a power law; second, an energy transfer towards smaller wave numbers, which corresponds in the physical space to a coalescence of magnetic islands. Finally, the spectra in the periodic directions exhibit a strongly anisotropic behavior
The transmission probability method in one-dimensional cylindrical geometry
International Nuclear Information System (INIS)
Rubin, I.E.
1983-01-01
The collision probability method widely used in solving the problems of neutron transpopt in a reactor cell is reliable for simple cells with small number of zones. The increase of the number of zones and also taking into account the anisotropy of scattering greatly increase the scope of calculations. In order to reduce the time of calculation the transmission probability method is suggested to be used for flux calculation in one-dimensional cylindrical geometry taking into account the scattering anisotropy. The efficiency of the suggested method is verified using the one-group calculations for cylindrical cells. The use of the transmission probability method allows to present completely angular and spatial dependences is neutrons distributions without the increase in the scope of calculations. The method is especially effective in solving the multi-group problems
Induced Charge Fluctuations in Semiconductor Detectors with a Cylindrical Geometry
Samedov, Victor V.
2018-01-01
Now, compound semiconductors are very appealing for hard X-ray room-temperature detectors for medical and astrophysical applications. Despite the attractive properties of compound semiconductors, such as high atomic number, high density, wide band gap, low chemical reactivity and long-term stability, poor hole and electron mobility-lifetime products degrade the energy resolution of these detectors. The main objective of the present study is in development of a mathematical model of the process of the charge induction in a cylindrical geometry with accounting for the charge carrier trapping. The formulae for the moments of the distribution function of the induced charge and the formulae for the mean amplitude and the variance of the signal at the output of the semiconductor detector with a cylindrical geometry were derived. It was shown that the power series expansions of the detector amplitude and the variance in terms of the inverse bias voltage allow determining the Fano factor, electron mobility lifetime product, and the nonuniformity level of the trap density of the semiconductor material.
First wall fusion blanket temperature variation - slab geometry
International Nuclear Information System (INIS)
Fillo, J.A.
1978-01-01
The first wall of a fusion blanket is approximated by a slab, with the surface facing the plasma subjected to an applied heat flux, while the rear surface is convectively cooled. The relevant parameters affecting the heat transfer during the early phases of heating as well as for large times are established. Analytical solutions for the temperature variation with time and space are derived. Numerical calculations for an aluminum and stainless steel slab are performed for a wall loading of 1 MW(th)/m 2 . Both helium and water cooling are considered. (Auth.)
Visualizing Three-dimensional Slab Geometries with ShowEarthModel
Chang, B.; Jadamec, M. A.; Fischer, K. M.; Kreylos, O.; Yikilmaz, M. B.
2017-12-01
Seismic data that characterize the morphology of modern subducted slabs on Earth suggest that a two-dimensional paradigm is no longer adequate to describe the subduction process. Here we demonstrate the effect of data exploration of three-dimensional (3D) global slab geometries with the open source program ShowEarthModel. ShowEarthModel was designed specifically to support data exploration, by focusing on interactivity and real-time response using the Vrui toolkit. Sixteen movies are presented that explore the 3D complexity of modern subduction zones on Earth. The first movie provides a guided tour through the Earth's major subduction zones, comparing the global slab geometry data sets of Gudmundsson and Sambridge (1998), Syracuse and Abers (2006), and Hayes et al. (2012). Fifteen regional movies explore the individual subduction zones and regions intersecting slabs, using the Hayes et al. (2012) slab geometry models where available and the Engdahl and Villasenor (2002) global earthquake data set. Viewing the subduction zones in this way provides an improved conceptualization of the 3D morphology within a given subduction zone as well as the 3D spatial relations between the intersecting slabs. This approach provides a powerful tool for rendering earth properties and broadening capabilities in both Earth Science research and education by allowing for whole earth visualization. The 3D characterization of global slab geometries is placed in the context of 3D slab-driven mantle flow and observations of shear wave splitting in subduction zones. These visualizations contribute to the paradigm shift from a 2D to 3D subduction framework by facilitating the conceptualization of the modern subduction system on Earth in 3D space.
Juan de Fuca slab geometry and its relation to Wadati-Benioff zone seismicity
McCrory, Patricia A.; Blair, J. Luke; Waldhause, Felix; Oppenheimer, David H.
2012-01-01
A new model of the subducted Juan de Fuca plate beneath western North America allows first-order correlations between the occurrence of Wadati-Benioff zone earthquakes and slab geometry, temperature, and hydration state. The geo-referenced 3D model, constructed from weighted control points, integrates depth information from earthquake locations and regional seismic velocity studies. We use the model to separate earthquakes that occur in the Cascadia forearc from those that occur within the underlying Juan de Fuca plate and thereby reveal previously obscured details regarding the spatial distribution of earthquakes. Seismicity within the slab is most prevalent where the slab is warped beneath northwestern California and western Washington suggesting that slab flexure, in addition to expected metamorphic dehydration processes, promotes earthquake occurrence within the subducted oceanic plate. Earthquake patterns beneath western Vancouver Island are consistent with slab dehydration processes. Conversely, the lack of slab earthquakes beneath western Oregon is consistent with an anhydrous slab. Double-differenced relocated seismicity resolves a double seismic zone within the slab beneath northwestern California that strongly constrains the location of the plate interface and delineates a cluster of seismicity 10 km above the surface that includes the 1992 M7.1 Mendocino earthquake. We infer that this earthquake ruptured a surface within the Cascadia accretionary margin above the Juan de Fuca plate. We further speculate that this earthquake is associated with a detached fragment of former Farallon plate. Other subsurface tectonic elements within the forearc may have the potential to generate similar damaging earthquakes.
Slab Geometry and Segmentation on Seismogenic Subduction Zone; Insight from gravity gradients
Saraswati, A. T.; Mazzotti, S.; Cattin, R.; Cadio, C.
2017-12-01
Slab geometry is a key parameter to improve seismic hazard assessment in subduction zones. In many cases, information about structures beneath subduction are obtained from geophysical dedicated studies, including geodetic and seismic measurements. However, due to the lack of global information, both geometry and segmentation in seismogenic zone of many subductions remain badly-constrained. Here we propose an alternative approach based on satellite gravity observations. The GOCE (Gravity field and steady-state Ocean Circulation Explorer) mission enables to probe Earth deep mass structures from gravity gradients, which are more sensitive to spatial structure geometry and directional properties than classical gravitational data. Gravity gradients forward modeling of modeled slab is performed by using horizontal and vertical gravity gradient components to better determine slab geophysical model rather than vertical gradient only. Using polyhedron method, topography correction on gravity gradient signal is undertaken to enhance the anomaly signal of lithospheric structures. Afterward, we compare residual gravity gradients with the calculated signals associated with slab geometry. In this preliminary study, straightforward models are used to better understand the characteristic of gravity gradient signals due to deep mass sources. We pay a special attention to the delineation of slab borders and dip angle variations.
Slab1.0: A three-dimensional model of global subduction zone geometries
Hayes, Gavin P.; Wald, David J.; Johnson, Rebecca L.
2012-01-01
We describe and present a new model of global subduction zone geometries, called Slab1.0. An extension of previous efforts to constrain the two-dimensional non-planar geometry of subduction zones around the focus of large earthquakes, Slab1.0 describes the detailed, non-planar, three-dimensional geometry of approximately 85% of subduction zones worldwide. While the model focuses on the detailed form of each slab from their trenches through the seismogenic zone, where it combines data sets from active source and passive seismology, it also continues to the limits of their seismic extent in the upper-mid mantle, providing a uniform approach to the definition of the entire seismically active slab geometry. Examples are shown for two well-constrained global locations; models for many other regions are available and can be freely downloaded in several formats from our new Slab1.0 website, http://on.doi.gov/d9ARbS. We describe improvements in our two-dimensional geometry constraint inversion, including the use of ‘average’ active source seismic data profiles in the shallow trench regions where data are otherwise lacking, derived from the interpolation between other active source seismic data along-strike in the same subduction zone. We include several analyses of the uncertainty and robustness of our three-dimensional interpolation methods. In addition, we use the filtered, subduction-related earthquake data sets compiled to build Slab1.0 in a reassessment of previous analyses of the deep limit of the thrust interface seismogenic zone for all subduction zones included in our global model thus far, concluding that the width of these seismogenic zones is on average 30% larger than previous studies have suggested.
Slab Geometry and Stress State of the Southwestern Colombia Subduction Zone
Chang, Ying
A high rate of intermediate-depth earthquakes is concentrates in the Cauca cluster (3.5°N-5.5°N) and isolated from nearby seismicity in the southwestern Colombia subduction zone. Previously-studied nests of intermediate-depth earthquakes show that a high seismicity rate is often associated with a slab tear, detachment, or contortion. The cause of the less-studied Cauca cluster is unknown. To investigate the cause, we image the slab geometry using precise relative locations of intermediate-depth earthquakes. We use the earthquake catalog produced and seismic waveforms recorded by the Colombian National Seismic Network from January 2010 to March 2014. We calculate the focal mechanisms to examine whether the earthquakes reactivate pre-existing faults or form new fractures. The focal mechanisms are inverted for the intraslab stress field to check the stress guide hypothesis and to evaluate the stress orientations with regard to the change in the slab geometry. The earthquake relocations indicate that the Cauca segment has a continuous 20 km thick seismic zone and increases in dip angle from north to south. Two 40-km-tall fingers of earthquakes extend out of the slab and into the mantle wedge. Different from the previously-studied nests, the Cauca cluster does not correspond to slab contortions or tearing. The cluster may be associated with a high amount of dehydrated fluid. The determined focal mechanisms of 69 earthquakes have various types and variably-oriented nodal planes, corresponding to the reactivation of pre-existing faults and the formation of new fractures. The results of stress inversion show that the extensional axis in the northern Cauca segment is in the plane of the slab and 25° from the downdip direction, and the southern part has along-strike extension. The compression is subnormal to the plane of the slab. The stress field supports the stress guide hypothesis and shows a consistent rotation with increase in slab dip angle.
Stability of a two-volume MRxMHD model in slab geometry
Tuen, Li Huey
background and perturbed magnetic fields to existing cylindrical working. An expression is formulated for the stability eigenvalues by creating a model for the slab geometry system. The eigenvalues for system stability at a minimum energy state are found to depend upon the rationality of the magnetic field pitch at resonant surfaces. Various system parameter scans are conducted to determine their affect upon system stability and their implications. While tearing instabilities exist at low order rational resonances, investigating the instability of high-order rationals requires study of pressure-driven instabilities.
Optical escape factors for Doppler profiles in spherical, cylindrical and plane parallel geometries
International Nuclear Information System (INIS)
Otsuka, Masamoto.
1977-12-01
Optical escape factors for Doppler profiles in spherical, cylindrical and plane parallel geometries are tabulated over the range of optical depths from 10 -3 to 10 5 . Relations with the known formulae are discussed also. (auth.)
Two-group Analysis of Xenon Stability in Slab Geometry by Modal Expansion
International Nuclear Information System (INIS)
Norinder, O.
1963-05-01
Xenon spatial stability is analyzed with the flux represented by two neutron energy groups. General formulas are given for expansions in a system of modes. Detailed formulas are recorded for a slab described by sinusoidal modes. A short description is given of a Mercury Autocode program for numerical calculations in slab geometry. The essential input parameters and results are noted for 80 computed cases. The main body of the calculations were intended to clarify the xenon stability properties of the Marviken reactor, which was found to have a sufficient margin against unstable xenon oscillations. The neutron flux detection and the control rod insertion in the slab were found to have a large influence on the stability in spite of the nonexistence of space-selective control in the systems investigated. Very good agreement was found between stability limits calculated according to Randall and St. John and stability limits calculated by the program
Two-group Analysis of Xenon Stability in Slab Geometry by Modal Expansion
Energy Technology Data Exchange (ETDEWEB)
Norinder, O
1963-05-15
Xenon spatial stability is analyzed with the flux represented by two neutron energy groups. General formulas are given for expansions in a system of modes. Detailed formulas are recorded for a slab described by sinusoidal modes. A short description is given of a Mercury Autocode program for numerical calculations in slab geometry. The essential input parameters and results are noted for 80 computed cases. The main body of the calculations were intended to clarify the xenon stability properties of the Marviken reactor, which was found to have a sufficient margin against unstable xenon oscillations. The neutron flux detection and the control rod insertion in the slab were found to have a large influence on the stability in spite of the nonexistence of space-selective control in the systems investigated. Very good agreement was found between stability limits calculated according to Randall and St. John and stability limits calculated by the program.
Ziegler, Ronny; Brendel, Bernhard; Rinneberg, Herbert; Nielsen, Tim
2009-01-21
Using a statistical (chi-square) test on simulated data and a realistic noise model derived from the system's hardware we study the performance of diffuse optical tomography systems for fluorescence imaging. We compare the predicted smallest size of detectable lesions at various positions in slab and cup geometry and model how detection sensitivity depends on breast compression and lesion fluorescence contrast. Our investigation shows that lesion detection is limited by relative noise in slab geometry and by absolute noise in cup geometry.
Energy corrections in pulsed neutron measurements for cylindrical geometry
International Nuclear Information System (INIS)
Drozdowicz, K.; Woznicka, U.
1982-01-01
A solution of the thermal neutron diffusion equation for a two-region concentric cylindrical system, with a constant neutron flux in the inner medium assumed, is given. The velocity-averaged dynamic parameters for thermal neutrons are used in the method. The corrections due to the diffusion cooling are introduced into the dynamic material buckling and into the velocity distribution of the thermal neutron flux. Detailed relations obtained for a hydrogenous moderator are given. Results of the measurements of the thermal neutron macroscopic absorption cross-sections for the samples in the two-region cylindrical systems are presented. (author)
A scalar flux - oriented method for the transport equation in slab geometry
International Nuclear Information System (INIS)
Budd, C.
1981-01-01
A new method for solving the neutron transport equation is described. An unusual feature of this method is that it deals principally with scalar fluxes rather than angular fluxes. An alternative approach in slab geometry promises to be cheaper to run and does not suffer from many of the problems of the discrete ordinates method. It also appears possible to extend the method to several dimensions and this is discussed. (U.K.)
International Nuclear Information System (INIS)
Barros, R.C. de; Larsen, E.W.
1991-01-01
A generalization of the one-group Spectral Green's Function (SGF) method is developed for multigroup, slab-geometry discrete ordinates (S N ) problems. The multigroup SGF method is free from spatial truncation errors; it generated numerical values for the cell-edge and cell-average angular fluxes that agree with the analytic solution of the multigroup S N equations. Numerical results are given to illustrate the method's accuracy
Studies of Superfluid 3He Confined to a Regular Submicron Slab Geometry, Using SQUID NMR
International Nuclear Information System (INIS)
Casey, Andrew; Corcoles, Antonio; Lusher, Chris; Cowan, Brian; Saunders, John
2006-01-01
The effect on the superfluid ground state of confining p-wave superfluid 3He in regular geometries of characteristic size comparable to the diameter of the Cooper pair remains relatively unexplored, in part because of the demands placed by experiments on the sensitivity of the measuring technique. In this paper we report preliminary experiments aimed at the study of 3He confined to a slab geometry. The NMR response of a series of superfluid samples has been investigated using a SQUID NMR amplifier. The sensitivity of this NMR spectrometer enables samples of order 1017 spins, with low filling factor, to be studied with good resolution
Comparison of collision operators for drift and MHD-interchange modes in unsheared slab geometry
International Nuclear Information System (INIS)
Rewoldt, G.; Tang, W.M.; Hastie, R.J.
1986-02-01
The general procedure for the kinetic analysis of low-frequency electrostatic and electromagnetic modes in toroidal geometry is now well known. In the collisionless limit, the relevant dynamics (e.g., trapped particles, resonances, etc.) can be treated appropriately. However, with the introduction of collisional effects, it is customary, for tractability, to employ model collision operators which do not rigorously satisfy all conservation properties of more exact collision operators. Insight into the essential required features of such operators can be gained by studying models with increasing levels of completeness for a simpler, unsheared slab geometry. The results presented here for this simpler geometry can provide guidance in choosing model collision operators for toroidal-geometry kinetic calculations. 6 refs., 3 figs
International Nuclear Information System (INIS)
Petersen, Claudio Zen; Vilhena, Marco T.; Barros, Ricardo C.
2009-01-01
In this paper the application of the Laplace transform method is described in order to determine the energy-dependent albedo matrix that is used in the boundary conditions multigroup neutron diffusion eigenvalue problems in slab geometry for nuclear reactor global calculations. In slab geometry, the diffusion albedo substitutes without approximation the baffle-reflector system around the active domain. Numerical results to typical test problems are shown to illustrate the accuracy and the efficiency of the Chebysheff acceleration scheme. (orig.)
Cell homogenization methods for pin-by-pin core calculations tested in slab geometry
International Nuclear Information System (INIS)
Yamamoto, Akio; Kitamura, Yasunori; Yamane, Yoshihiro
2004-01-01
In this paper, performances of spatial homogenization methods for fuel or non-fuel cells are compared in slab geometry in order to facilitate pin-by-pin core calculations. Since the spatial homogenization methods were mainly developed for fuel assemblies, systematic study of their performance for the cell-level homogenization has not been carried out. Importance of cell-level homogenization is recently increasing since the pin-by-pin mesh core calculation in actual three-dimensional geometry, which is less approximate approach than current advanced nodal method, is getting feasible. Four homogenization methods were investigated in this paper; the flux-volume weighting, the generalized equivalence theory, the superhomogenization (SPH) method and the nonlinear iteration method. The last one, the nonlinear iteration method, was tested as the homogenization method for the first time. The calculations were carried out in simplified colorset assembly configurations of PWR, which are simulated by slab geometries, and homogenization performances were evaluated through comparison with the reference cell-heterogeneous calculations. The calculation results revealed that the generalized equivalence theory showed best performance. Though the nonlinear iteration method can significantly reduce homogenization error, its performance was not as good as that of the generalized equivalence theory. Through comparison of the results obtained by the generalized equivalence theory and the superhomogenization method, important byproduct was obtained; deficiency of the current superhomogenization method, which could be improved by incorporating the 'cell-level discontinuity factor between assemblies', was clarified
Multi-level methods for solving multigroup transport eigenvalue problems in 1D slab geometry
International Nuclear Information System (INIS)
Anistratov, D. Y.; Gol'din, V. Y.
2009-01-01
A methodology for solving eigenvalue problems for the multigroup neutron transport equation in 1D slab geometry is presented. In this paper we formulate and compare different variants of nonlinear multi-level iteration methods. They are defined by means of multigroup and effective one-group low-order quasi diffusion (LOQD) equations. We analyze the effects of utilization of the effective one-group LOQD problem for estimating the eigenvalue. We present numerical results to demonstrate the performance of the iteration algorithms in different types of reactor-physics problems. (authors)
Topological superfluids confined in a regular nano-scale slab geometry
Energy Technology Data Exchange (ETDEWEB)
Saunders, John; Bennett, Robert; Levitin, Lev; Casey, Andrew; Cowan, Brian [Department of Physics, Royal Holloway University of London, Egham, Surrey, TW20 0EX (United Kingdom); Parpia, Jeevak [Department of Physics, Cornell University, Ithaca, NY 14853 (United States); Drung, Dietmar; Schurig, Thomas [Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, D-19587, Berlin (Germany)
2012-07-01
Superfluid 3He confined in a regular nano-fabricated slab geometry provides a model system for the investigation of surface and thin film effects in a p-wave superfluid. We have fabricated and cooled such samples to well below 1 mK for the first time, and investigated their NMR response, exploiting a SQUID NMR spectrometer of exquisite sensitivity. We have used NMR on a 650 nm thick superfluid slab to identify the profound effect of confinement on the relative stability of the A and B phases and to make quantitative measurements of the suppression and surface induced distortion of the order parameter. In these systems the effective confinement length scale (slab thickness/superfluid coherence length) is the new tuning parameter. Increasing confinement should stabilize new p-wave superfluid states of matter, such as the quasi-2D gapped A phase or the planar phase. Nanofluidic samples of superfluid 3He promise a route to explore topological superfluids and their surface, edge and defect-bound excitations under well controlled conditions.
Performance of a liquid argon electromagnetic calorimeter with a cylindrical accordion geometry
International Nuclear Information System (INIS)
Aubert, B.; Bazan, A.; Beaugiraud, B.; Colas, J.; Leflour, T.; Maire, M.; Vialle, J.P.; Wingerter-Seez, I.; Zolnierowski, Y.P.; Gordon, H.A.; Radeka, V.; Rahm, D.; Stephani, D.; Bulgakov, N.; Chevalley, J.L.; Fabjan, C.W.; Fournier, D.; Gildemeister, O.; Jenni, P.; Nessi, M.; Nessi-Tedaldi, F.; Pepe, M.; Richter, W.; Soderqvist, J.; Vuillemin, V.; Baze, J.M.; Gosset, L.; Lavocat, P.; Lottin, J.P.; Mansoulie, B.; Meyer, J.P.; Renardy, J.R.; Teiger, J.; Zaccone, H.; Battistoni, G.; Camin, D.V.; Cavalli, D.; Costa, G.; Cravero, A.; Ferrari, A.; Gianotti, F.; Mandelli, L.; Mazzanti, M.; Perini, L.; Sciamanna, M.; Auge, E.; Chase, R.; Chollet, J.C.; La Taille, C. de; Fayard, L.; Hrisoho, A.; Jean, P.; Iconomidou-Fayard, L.; Le Meur, G.; Merkel, B.; Noppe, J.M.; Parrour, G.; Petroff, P.; Repellin, J.P.; Schaffer, A.; Seguin, N.; Unal, G.; Fuglesang, C.; Lefebvre, M.
1993-01-01
A prototype of a lead liquid argon accordion calorimeter with two types of cylindrical geometry was constructed and equipped with high speed readout electronics. The energy resolution for electrons is 10%/√E (GeV) with a local constant term of 0.65%. The resolutions obtained for position and angular measurements are given. (orig.)
International Nuclear Information System (INIS)
Mathews, K.; Sjoden, G.; Minor, B.
1994-01-01
The exponential characteristic spatial quadrature for discrete ordinates neutral particle transport in slab geometry is derived and compared with current methods. It is similar to the linear characteristic (or, in slab geometry, the linear nodal) quadrature but differs by assuming an exponential distribution of the scattering source within each cell, S(x) = a exp(bx), whose parameters are root-solved to match the known (from the previous iteration) average and first moment of the source over the cell. Like the linear adaptive method, the exponential characteristic method is positive and nonlinear but more accurate and more readily extended to other cell shapes. The nonlinearity has not interfered with convergence. The authors introduce the ''exponential moment functions,'' a generalization of the functions used by Walters in the linear nodal method, and use them to avoid numerical ill-conditioning. The method exhibits O(Δx 4 ) truncation error on fine enough meshes; the error is insensitive to mesh size for coarse meshes. In a shielding problem, it is accurate to 10% using 16-mfp-thick cells; conventional methods err by 8 to 15 orders of magnitude. The exponential characteristic method is computationally more costly per cell than current methods but can be accurate with very thick cells, leading to increased computational efficiency on appropriate problems
International Nuclear Information System (INIS)
Goncalves, Glenio Aguiar
2003-01-01
In this work, we are reported analytical solutions for the transport equation for neutral particles in cylindrical and cartesian geometry. For the cylindrical geometry, it is applied the Hankel transform of order zero in the S N approximation of the one-dimensional cylindrical transport equation, assuming azimuthal symmetry and isotropic scattering. This procedure is coined HTSN method. The anisotropic problem is handled using the decomposition method, generating a recursive approach, which the HTSN solution is used as initial condition. For cartesian geometry, the one and two dimensional transport equation is derived in the angular variable as many time as the degree of the anisotropic scattering. This procedure leads to set of integro-differential plus one differential equation that can be really solved by the variable separation method. Following this procedure, it was possible to come out with the Case solution for the one-dimensional problem. Numerical simulations are reported for the cylindrical transport problem both isotropic and anisotropic case of quadratic degree. (author)
International Nuclear Information System (INIS)
Fischer, E.A.
1981-01-01
Basic problems of the definition and calculation of the perpendicular cell diffusion coefficient in slab lattices of fast critical assemblies are discussed in terms of an integral transport formalism. Numerical estimates of correction terms are given which are usually neglected. In addition, a detailed derivation of an equation for the diffusion-coefficient in a cylindrical low-density channel is given
International Nuclear Information System (INIS)
Abreu, Marcos Pimenta de
1998-01-01
We describe a numerical method applied to the first-order form of one-speed slab-geometry discrete ordinates equations modelling time-independent neutron transport problems with anisotropic scattering, with no interior source and defined in a nonmultiplying homogeneous host medium. Our numerical method is concerned with the generation of the spectrum and of a vector basis for the null space of the one-speed slab-geometry discrete ordinates operator. Moreover, it allows us to overcome the difficulties introduced in previous methods by anisotropic scattering and by angular quadrature sets of high order. To illustrate the positive features of our numerical method, we present numerical results for one-speed slab-geometry neutron transport model problems with anisotropic scattering
International Nuclear Information System (INIS)
Sanchez, Richard.
1975-11-01
The Integral Transform Method for the neutron transport equation has been developed in last years by Asaoka and others. The method uses Fourier transform techniques in solving isotropic one-dimensional transport problems in homogeneous media. The method has been extended to linearly anisotropic transport in one-dimensional homogeneous media. Series expansions were also obtained using Hembd techniques for the new anisotropic matrix elements in cylindrical geometry. Carlvik spatial-spherical harmonics method was generalized to solve the same problem. By applying a relation between the isotropic and anisotropic one-dimensional kernels, it was demonstrated that anisotropic matrix elements can be calculated by a linear combination of a few isotropic matrix elements. This means in practice that the anisotropic problem of order N with the N+2 isotropic matrix for the plane and spherical geometries, and N+1 isotropic matrix for cylindrical geometries can be solved. A method of solving linearly anisotropic one-dimensional transport problems in homogeneous media was defined by applying Mika and Stankiewicz observations: isotropic matrix elements were computed by Hembd series and anisotropic matrix elements then calculated from recursive relations. The method has been applied to albedo and critical problems in cylindrical geometries. Finally, a number of results were computed with 12-digit accuracy for use as benchmarks [fr
A new approach to obtaining the roots of the dispersion equation for slab geometry multiplying media
International Nuclear Information System (INIS)
Silva, Davi J.M.; Barros, Ricardo C.; Alves Filho, Hermes
2013-01-01
In this work we describe an alternative approach for obtaining the roots of the dispersion equation. For the mathematical model, we used the slab-geometry neutron transport equation in the discrete ordinates (S N ), formulation, considering isotropic scattering and monoenergetic model. The basic idea is to find a basis for the kernel of the S N differential operator, whose elements are exponential eigenfunctions corresponding to distinct eigenvalues which are the roots of the dispersion equation. That strategy yields a gain in programming computational codes, including the strategy used to obtain the purely imaginary eigenvalues and their associated complex eigenfunctions, that appear in the spectral analysis of the S N equations in multiplying media. These eigenvalues and corresponding eigenfunctions are used to obtain the parameters of the auxiliary equations of the spectral nodal methods, e.g., the spectral diamond (SD) auxiliary equation. (author)
A direct hybrid SN method for slab-geometry lattice calculations
International Nuclear Information System (INIS)
Silva, Davi J.M.; Barros, Ricardo C.; Zani, Jose H.
2011-01-01
In this work we describe a hybrid direct method for calculating the thermal disadvantage factor and the neutron flux distribution in fuel-moderator lattices. For the mathematical model, we use the one-speed slab-geometry discrete ordinates (S N ) transport equation with linearly anisotropic scattering. The basic idea is to use higher order angular quadrature set in the highly absorbing fuel region (S NF ) and lower order angular quadrature set in the diffusive moderator region (S NM ) , i.e., N F > N M . We apply special continuity conditions based on the equivalence of the S N and P N-1 equations, which characterize the hybrid model. Numerical results to a typical model problem are given to illustrate the accuracy and the efficiency of the offered hybrid method. (author)
Effect of drift-acoustic waves on magnetic island stability in slab geometry
International Nuclear Information System (INIS)
Fitzpatrick, R.; Waelbroeck, F.L.
2005-01-01
A mathematical formalism is developed for calculating the ion polarization term in the Rutherford island width evolution equation in the presence of drift-acoustic waves. The calculation is fully nonlinear, includes both ion and electron diamagnetic effects, as well as ion compressibility, but is performed in slab geometry. Magnetic islands propagating in a certain range of phase velocities are found to emit drift-acoustic waves. Wave emission gives rise to rapid oscillations in the ion polarization term as the island phase velocity varies, and also generates a net electromagnetic force acting on the island region. Increasing ion compressibility is found to extend the range of phase velocities over which drift-acoustic wave emission occurs in the electron diamagnetic direction
A direct hybrid S{sub N} method for slab-geometry lattice calculations
Energy Technology Data Exchange (ETDEWEB)
Silva, Davi J.M.; Barros, Ricardo C., E-mail: rcbarros@pq.cnpq.b [Universidade do Estado do Rio de Janeiro (IPRJ/UERJ), Nova Friburgo, RJ (Brazil). Programa de Pos-graduacao em Modelagem Computacional; Zani, Jose H. [Fundacao Educacional Serra dos Orgaos, Teresopolis, RJ (Brazil). Ciencia da Computacao
2011-07-01
In this work we describe a hybrid direct method for calculating the thermal disadvantage factor and the neutron flux distribution in fuel-moderator lattices. For the mathematical model, we use the one-speed slab-geometry discrete ordinates (S{sub N}) transport equation with linearly anisotropic scattering. The basic idea is to use higher order angular quadrature set in the highly absorbing fuel region (S{sub NF}) and lower order angular quadrature set in the diffusive moderator region (S{sub NM}) , i.e., N{sub F} > N{sub M}. We apply special continuity conditions based on the equivalence of the S{sub N} and P{sub N-1} equations, which characterize the hybrid model. Numerical results to a typical model problem are given to illustrate the accuracy and the efficiency of the offered hybrid method. (author)
Quasiparticle interference in heavy fermion superconductors. Role of the slab geometry
Energy Technology Data Exchange (ETDEWEB)
Lambert, Fabian [Institute fuer Theoretische Physik III, Ruhr-Universitaet Bochum, D-44801 Bochum (Germany); Akbari, Alireza [Asia Pacific Center for Theoretical Physics (APCTP) (Korea, Republic of); Department of Physics, and Max Planck POSTECH Center for Complex Phase Materials, POSTECH, Pohang 790-784 (Korea, Republic of); Thalmeier, Peter [Max Planck Institute for the Chemical Physics of Solids, D-01187 Dresden (Germany); Eremin, Ilya [Institute fuer Theoretische Physik III, Ruhr-Universitaet Bochum, D-44801 Bochum (Germany); Institute of Physics, Kazan (Volga Region) Federal University, 420008 Kazan (Russian Federation)
2016-07-01
We analyze theoretically the quasiparticle interference in the heavy fermion superconductors CeCoIn{sub 5} and UPt{sub 3} as a direct method to investigate the gap symmetry. In contrast to the prior attempts that computed QPI patterns for some effective two-dimensional models or by performing calculations for various k{sub z} cuts and then averaging the final result, we perfom the calculations for the three-dimensional models in the slab geometry and investigate possible effects of the finite sample size, topology, and surface termination. Comparing with the results of prior analysis of the bulk system we can conclude on the importance of the possible surface states for determining the QPI pattern.
International Nuclear Information System (INIS)
Dominguez, Dany S.; Oliveira, Francisco B.S.; Barros, Ricardo C.
2003-01-01
We present in this paper a multiplatform computational code to calculate elements of Gauss-Legendre angular quadrature sets of arbitrary order used in slab-geometry discrete ordinates (S N ) formulation of neutron transport equation. In the code, the values can be computed with arbitrary arithmetic precision based on the approach of exact computing floating-point numbers. Calculation routines have been developed in the common language ANSI C using standard compiler gcc and the libraries of the open code GMP (GNU Multi precision Library). The code has a graphical interface in order to facilitate user interaction and numerical results analysis. The code architecture allows it to run on different platforms such as Unix, Linux and Windows. Numerical results and performance measures are also given. (author)
Spatial Treatment of the Slab-geometry Discrete Ordinates Equations Using Artificial Neural Networks
International Nuclear Information System (INIS)
Brantley, P S
2001-01-01
An artificial neural network (ANN) method is developed for treating the spatial variable of the one-group slab-geometry discrete ordinates (S N ) equations in a homogeneous medium with linearly anisotropic scattering. This ANN method takes advantage of the function approximation capability of multilayer ANNs. The discrete ordinates angular flux is approximated by a multilayer ANN with a single input representing the spatial variable x and N outputs representing the angular flux in each of the discrete ordinates angular directions. A global objective function is formulated which measures how accurately the output of the ANN approximates the solution of the discrete ordinates equations and boundary conditions at specified spatial points. Minimization of this objective function determines the appropriate values for the parameters of the ANN. Numerical results are presented demonstrating the accuracy of the method for both fixed source and incident angular flux problems
Methods for computing SN eigenvalues and eigenvectors of slab geometry transport problems
International Nuclear Information System (INIS)
Yavuz, Musa
1998-01-01
We discuss computational methods for computing the eigenvalues and eigenvectors of single energy-group neutral particle transport (S N ) problems in homogeneous slab geometry, with an arbitrary scattering anisotropy of order L. These eigensolutions are important when exact (or very accurate) solutions are desired for coarse spatial cell problems demanding rapid execution times. Three methods, one of which is 'new', are presented for determining the eigenvalues and eigenvectors of such S N problems. In the first method, separation of variables is directly applied to the S N equations. In the second method, common characteristics of the S N and P N-1 equations are used. In the new method, the eigenvalues and eigenvectors can be computed provided that the cell-interface Green's functions (transmission and reflection factors) are known. Numerical results for S 4 test problems are given to compare the new method with the existing methods
Methods for computing SN eigenvalues and eigenvectors of slab geometry transport problems
International Nuclear Information System (INIS)
Yavuz, M.
1997-01-01
We discuss computational methods for computing the eigenvalues and eigenvectors of single energy-group neutral particle transport (S N ) problems in homogeneous slab geometry, with an arbitrary scattering anisotropy of order L. These eigensolutions are important when exact (or very accurate) solutions are desired for coarse spatial cell problems demanding rapid execution times. Three methods, one of which is 'new', are presented for determining the eigenvalues and eigenvectors of such S N problems. In the first method, separation of variables is directly applied to the S N equations. In the second method, common characteristics of the S N and P N-1 equations are used. In the new method, the eigenvalues and eigenvectors can be computed provided that the cell-interface Green's functions (transmission and reflection factors) are known. Numerical results for S 4 test problems are given to compare the new method with the existing methods. (author)
Contribution to study of interfaces instabilities in plane, cylindrical and spherical geometry
Toque, Nathalie
1996-12-01
This thesis proposes several experiments of hydrodynamical instabilities which are studied, numerically and theoretically. The experiments are in plane and cylindrical geometry. Their X-ray radiographies show the evolution of an interface between two solid media crossed by a detonation wave. These materials are initially solid. They become liquide under shock wave or stay between two phases, solid and liquid. The numerical study aims at simulating with the codes EAD and Ouranos, the interfaces instabilities which appear in the experiments. The experimental radiographies and the numerical pictures are in quite good agreement. The theoretical study suggests to modelise a spatio-temporal part of the experiments to obtain the quantitative development of perturbations at the interfaces and in the flows. The models are linear and in plane, cylindrical and spherical geometry. They preceed the inoming study of transition between linear and non linear development of instabilities in multifluids flows crossed by shock waves.
International Nuclear Information System (INIS)
Feit, M.D.; Fleck, J.A. Jr.
1989-01-01
We describe a spectral method for solving the paraxial wave equation in cylindrical geometry that is based on expansion of the exponential evolution operator in a Taylor series and use of fast Fourier transforms to evaluate derivatives. A fourth-order expansion gives excellent agreement with a two-transverse-dimensional split-operator calculation at a fraction of the cost in computation time per z step and at a considerable savings in storage
(U) Influence of Compaction Model Form on Planar and Cylindrical Compaction Geometries
Energy Technology Data Exchange (ETDEWEB)
Fredenburg, David A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carney, Theodore Clayton [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Fichtl, Christopher Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ramsey, Scott D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2018-01-05
The dynamic compaction response of CeO_{2} is examined within the frameworks of the Ramp and P-a compaction models. Hydrocode calculations simulating the dynamic response of CeO_{2} at several distinct pressures within the compaction region are investigated in both planar and cylindrically convergent geometries. Findings suggest additional validation of the compaction models is warranted under complex loading configurations.
Energy Technology Data Exchange (ETDEWEB)
Rodney Whitaker
2007-12-17
In computer programs involving two-dimensional cylindrical geometry, it is often necessary to calculate the slant path distance in a given direction from a point to the boundary of a mesh cell. A subroutine, HOWFAR, has been written that accomplishes this, and is very economical in computer time. An example of its use is given in constructing the isophotes for a low altitude nuclear fireball.
International Nuclear Information System (INIS)
Czubek, J.A.; Woznicka, U.
1997-01-01
A solution of the neutron diffusion equation is given for a three layer cylindrical coaxial geometry. The calculation is performed in two neutron-energy groups which distinguish the thermal and epithermal neutron fluxes in the media irradiated by the fast point neutron source. The aim of the calculation is to define the neutron slowing down and migration lengths which are observed at a given point of the system. Generally, the slowing down and migration lengths are defined for an infinite homogenous medium (irradiated by the point neutron source) as a quotient of the neutron flux moment of the (2n + 2)-order to the moment of the 2n-order. Czubek(1992) introduced in the same manner the apparent neutron slowing down length and the apparent migration length for a given multi-region cylindrical geometry. The solutions in the present paper are applied to the method of semi-empirical calibration of neutron well-logging tools. The three-region cylindrical geometry corresponds to the borehole of radius R 1 surrounded by the intermediate region (e.g. mud cake) of thickness (R 2 -R 1 ) and finally surrounded by the geological formation which spreads from R 2 up to infinity. The cylinders of an infinite length are considered. The paper gives detailed solutions for the 0-th, 2-nd and 4-th neutron moments of the neutron fluxes for each neutron energy group and in each cylindrical layer. A comprehensive list of the solutions for integrals containing Bessel functions or their derivatives, which are absent in common tables of integrals, is also included. (author)
Energy Technology Data Exchange (ETDEWEB)
Czubek, J.A.; Woznicka, U. [The H. Niewodniczanski Inst. of Nuclear Physics, Cracow (Poland)
1997-12-31
A solution of the neutron diffusion equation is given for a three layer cylindrical coaxial geometry. The calculation is performed in two neutron-energy groups which distinguish the thermal and epithermal neutron fluxes in the media irradiated by the fast point neutron source. The aim of the calculation is to define the neutron slowing down and migration lengths which are observed at a given point of the system. Generally, the slowing down and migration lengths are defined for an infinite homogenous medium (irradiated by the point neutron source) as a quotient of the neutron flux moment of the (2n{sup +}2)-order to the moment of the 2n-order. Czubek(1992) introduced in the same manner the apparent neutron slowing down length and the apparent migration length for a given multi-region cylindrical geometry. The solutions in the present paper are applied to the method of semi-empirical calibration of neutron well-logging tools. The three-region cylindrical geometry corresponds to the borehole of radius R{sub 1} surrounded by the intermediate region (e.g. mud cake) of thickness (R{sub 2}-R{sub 1}) and finally surrounded by the geological formation which spreads from R{sub 2} up to infinity. The cylinders of an infinite length are considered. The paper gives detailed solutions for the 0-th, 2-nd and 4-th neutron moments of the neutron fluxes for each neutron energy group and in each cylindrical layer. A comprehensive list of the solutions for integrals containing Bessel functions or their derivatives, which are absent in common tables of integrals, is also included. (author) 6 refs, 2 figs
Energy Technology Data Exchange (ETDEWEB)
Sinjeri, Lj; Kulisic, P [Elektra - Zagreb, Zagreb (Yugoslavia)
1990-07-01
Low radioactive sources were used for experimental determination of optimal dimensions for cylindrical source using coaxial Ge(Li) detector. Then, calculational procedure is used to find optimal dimensions of cylindrical source. The results from calculational procedure confirm with experimental results. In such way the verification of calculational procedure is done and it can be used for determination of optimal geometry for low radioactive cylindrical sources. (author)
International Nuclear Information System (INIS)
Massimiliano, Rosa; Azmy, Y.Y.; Morel, J.E.
2005-01-01
The general expressions for the matrix elements of the discrete Sn-equivalent integral transport operator have been derived in slab geometry. Their asymptotic behavior has been investigated both for a homogeneous slab and for a heterogeneous slab characterized by a periodic material discontinuity wherein each optically thick cell is surrounded by two optically thin cells in a repeating pattern. In the case of a homogeneous slab, the asymptotic analysis conducted in a diffusive limit obtained as the thick limit of computational cell size for a highly scattering medium, has shown that the discretized integral transport operator is approximated by a sparse matrix characterized by a tri-diagonal diffusion-like coupling stencil. Also, the tri-diagonal matrix structure, characteristic of the diffusion coupling stencil, is approached at a fast exponential rate. In the case of periodically heterogeneous slab configurations, the asymptotic behavior investigated is that in which the cells' optical thicknesses are pushed apart, i.e. the thick is made thicker while the thin is made thinner at a prescribed rate. It has been shown that in this limit the discretized integral transport operator is approximated by a penta-diagonal structure. Notwithstanding, the discrete operator is amenable to algebraic transformations leading to a matrix representation still asymptotically approaching a tri-diagonal structure at a fast exponential rate. The existence of a low order tri-diagonal approximation to the full discrete integral transport operator in the case of a periodically heterogeneous slab might provide a basic understanding of the superior convergence properties of diffusion-based acceleration schemes observed in slab geometry, even in the presence of sharp material discontinuities. The obtained results also suggest that a sparse approximation to the S n -equivalent integral transport operator might itself be used as the low-order operator in an acceleration scheme for the
International Nuclear Information System (INIS)
Basta, C.
1982-01-01
Using the method of orthogonal colocation the boundary problem for a fix bed with cylindrical geometry was solved. The axial disposal term was despicable and the results were compared with those the explicit finite difference method. (E.G.) [pt
Energy Technology Data Exchange (ETDEWEB)
Mansur, Ralph S.; Moura, Carlos A., E-mail: ralph@ime.uerj.br, E-mail: demoura@ime.uerj.br [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Departamento de Engenharia Mecanica; Barros, Ricardo C., E-mail: rcbarros@pq.cnpq.br [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Departamento de Modelagem Computacional
2017-07-01
Presented here is an application of the Response Matrix (RM) method for adjoint discrete ordinates (S{sub N}) problems in slab geometry applied to energy-dependent source-detector problems. The adjoint RM method is free from spatial truncation errors, as it generates numerical results for the adjoint angular fluxes in multilayer slabs that agree with the numerical values obtained from the analytical solution of the energy multigroup adjoint SN equations. Numerical results are given for two typical source-detector problems to illustrate the accuracy and the efficiency of the offered RM computer code. (author)
International Nuclear Information System (INIS)
Ligou, J.; Thomi, P.A.
1973-01-01
1 - Nature of physical problem solved: Integral transport equation, anisotropy of diffusion in P1 approximation. SHADOK3 - cylindrical geometry; direct solution of the linear system. SHADOK4 - cylindrical geometry; Thermalization iteration; solution of the linear system with inverse matrix calculation. SHADOK5 - like SHADOK3 for spherical geometry. SHADOK6 - like SHADOK4 for spherical geometry. 2 - Method of solution: Analysis in terms of annuli for each of which polynomial approximation is applied. Dynamic allocation (for formulas see report TM(10)). 3 - Restrictions on the complexity of the problem: Relative accuracy of the Bickley functions about 1.0E-13
Numerical solution of neutron transport equations in discrete ordinates and slab geometry
International Nuclear Information System (INIS)
Serrano Pedraza, F.
1985-01-01
An unified formalism to solve numerically, between other equation, the neutron transport in discrete ordinates, slab geometry, several energy groups and independents of time, has been developed recently. Such a formalism cover some of the conventional schemes as diamond difference, (WDD) characteristic step (SC) lineal characteristic (LC), quadratic characteristic (QC) and lineal discontinuous. Unified formation gives before hand the convergence order of the previously selected scheme. In fact it allows besides to generate a big amount of numerical schemes, with which is also possible to solve numerical equations as soon as neutron transport. The essential purpose of this work was to solve the neutron transport equations in slab geometry and discrete ordinates considering several energy groups without to take under advisement time dependence based in the above mentioned unified formalism. To reach this purpose it was necesary to design a computer code with the name TNOD1 (Neutron transport in discrete ordinates and 1 dimension) which includes each one of the schemes already pointed out. there exist two numerical schemes, also recently developed, quadratic continuous (QC) and cubic continuous (CN), although covered by unified formalism, it has been possible to include them inside this computer code without make substantial changes in its structure. In chapter I, derivative of neutron transport equation independent of time is taken, for angular flux, including boundary conditions and discontinuity. In chapter II the neutron transport equations are obtained in multigroups, independents of time, for approximation of discrete ordinates. Description of theory related with unified formalism and its relationship with mentioned discretization schemes is presented in chapter III. Chapter IV describes the computer code developed and finally, in chapter V different numerical results obtained with TNOD1 program are shown. In Appendix A theorems and mathematical arguments used
International Nuclear Information System (INIS)
Carvalho-Santos, V.L.; Apolonio, F.A.; Oliveira-Neto, N.M.
2013-01-01
We study the Heisenberg model on cylindrically symmetric curved surfaces. Two kinds of excitations are considered. The first is given by the isotropic regime, yielding the sine-Gordon equation and π solitons are predicted. The second one is given by the XY model, leading to a vortex turning around the surface. Helical states are also considered, however, topological arguments cannot be used to ensure its stability. The energy and the anisotropy parameter which stabilizes the vortex state are explicitly calculated for two surfaces: catenoid and hyperboloid. The results show that the anisotropy and the vortex energy depends on the underlying geometry. -- Highlights: •Applying the anisotropic Heisenberg model on curved surfaces. •Appearance of topological solitons on curved surfaces with cylindrical symmetry. •Calculus of the vortex energy, which depends on curvature. •Discussion on features of non-topological helical-like states. •Vortex stability ensured by the anisotropy parameter value
International Nuclear Information System (INIS)
Murao, Y.; Iguchi, T.; Sugimoto, J.
1988-09-01
The reflooding behavior in a PWR with a combined injection type ECCS was studied by comparing the test results from Cylindrical Core Test Facility (CCTF), Slab Core Test Facility (SCTF) and Upper Plenum Test Facility (UPTF). Core thermal-hydraulics is discussed mainly based on SCTF test data. In addition, the water accumulation behavior in hot legs and the break-through characteristics at tie plate are discussed
Confinement of a non cylindrical z discharge by a cusp geometry
International Nuclear Information System (INIS)
Watteau, J.H.
1968-03-01
The plasma of a non-cylindrical z discharge is accumulated in the centre of a cusp geometry and then captured and confined by the rising cusp magnetic field. The cusp geometry is produced by two identical coaxial coils the currents of which are equal but in opposite directions. Stability and confinement properties of this zero minimum B geometry are recalled; in particular it is shown (the coils cross section being supposed punctual) that the magnetic well depth of the configuration without plasma is maximum for an optimum coils distance. Two modes of confinement are observed experimentally : - a collisional mode for which the plasma confinement is limited to 10 μsec (temperature 5 eV, density 7 x 10 16 cm -3 ) as a result of the gradual interpenetration of the plasma and of the magnetic field. - a collisionless mode (temperature 40 eV) where the radial leak thickness is of the order of the ion cyclotron radius. Plasma accumulation occurs even without confinement and is due to the non-cylindrical shape of the discharge chamber. The two-dimensional snow-plough model gives good account of the discharge dynamics. A comparison is made with plasma focus experiments: in particular experimental conditions (deuterium, pressure 1 torr,energy 3 kJ, current 100 kA) a 10 7 neutron yield is detected which appears to be connected with the unstable behavior of the discharge. (authors) [fr
The electrostatic cylindrical sheath in a plasma
International Nuclear Information System (INIS)
Wang Chunhua; Sun Xiaoxia; Bai Dongxue
2004-01-01
The electrostatic sheath with a cylindrical geometry in an ion-electron plasma is investigated. Assuming a Boltzmann response to electrons and cold ions with bulk flow, it is shown that the radius of the cylindrical geometry do not affect the sheath potential significantly. The authors also found that the sheath potential profile is steeper in the cylindrical sheath compared to the slab sheath. The distinct feature of the cylindrical sheath is that the ion density distribution is not monotonous. The sheath region can be divided into three regions, two ascendant regions and one descendant region. (author)
A successive over-relaxation for slab geometry Simplified SN method with interface flux iteration
International Nuclear Information System (INIS)
Yavuz, M.
1995-01-01
A Successive Over-Relaxation scheme is proposed for speeding up the solution of one-group slab geometry transport problems using a Simplified S N method. The solution of the Simplified S N method that is completely free from all spatial truncation errors is based on the expansion of the angular flux in spherical-harmonics solutions. One way to obtain the (numerical) solution of the Simplified S N method is to use Interface Flux Iteration, which can be considered as the Gauss-Seidel relaxation scheme; the new information is immediately used in the calculations. To accelerate the convergence, an over relaxation parameter is employed in the solution algorithm. The over relaxation parameters for a number of cases depending on scattering ratios and mesh sizes are determined by Fourier analyzing infinite-medium Simplified S 2 equations. Using such over relaxation parameters in the iterative scheme, a significant increase in the convergence of transport problems can be achieved for coarse spatial cells whose spatial widths are greater than one mean-free-path
Spin dynamics of superfluid 3He-B in a slab geometry
International Nuclear Information System (INIS)
Ishikawa, O.; Sasaki, Y.; Mizusaki, T.; Hirai, A.; Tsubota, M.
1989-01-01
The spin dynamics and the spin relaxation mechanisms of the superfluid 3 He-B were studied by using the NMR method in a slab geometry, where the superfluid 3 He-B was confined between narrow parallel plates with a gap smaller than the healing length of the n-texture and the magnetic field was applied and to the plates. The relaxation parameter in the Leggett-Takagi (LT) equations was determined from a line width measurement of the transverse CW NMR. By using the pulsed NMR method, spin dynamics were studied in the nonlinear region. The observed spin dynamics were in good agreement with a numerical calculation of the LT equations together with the relaxation parameter determined by the CW NMR. When the tipping angle became larger than a certain critical value, the superfluid 3 He-B entered the Brinkman-Smith (BS) state. In this case, they observed the slow relaxation process in the BS state and then the rapid recovery process from the BS state to the initial non-Leggett configuration. The slow process in the BS state was attributed to the surface relaxation mechanism due to the torque from the surface-field energy
Temperature-dependent pitch and phase diagram for incommensurate XY spins in a slab geometry
International Nuclear Information System (INIS)
Collins, M.; Saslow, W.M.
1996-01-01
Strain-engineered Heisenberg antiferromagnets recently have been produced by controlling the layer thickness of MnSe/ZnTe superlattices. Neutron-scattering studies reveal a spiral that tends to untwist with increasing temperature. To simulate this system, we employ an XY model with nearest- and second-nearest neighbor antiferromagnetic interactions. The bulk mean-field phase diagram has four possible phases, for the full range of the exchange constants. Monte Carlo calculations are performed for a slab geometry, using an algorithm that allows the system to choose incommensurate boundary conditions. The phase diagram is constructed by monitoring the spiral pitch as a function of temperature for a range of exchange constants. For appropriate exchange constants, good agreement is obtained with experiment. From the mean-field phase diagram it appears that strain engineering an NaCl structure in a superlattice configuration might produce a type of spiral phase, and an associated antiferromagnetic-to-spiral phase transition. copyright 1996 The American Physical Society
Effect of cosine current approximation in lattice cell calculations in cylindrical geometry
International Nuclear Information System (INIS)
Mohanakrishnan, P.
1978-01-01
It is found that one-dimensional cylindrical geometry reactor lattice cell calculations using cosine angular current approximation at spatial mesh interfaces give results surprisingly close to the results of accurate neutron transport calculations as well as experimental measurements. This is especially true for tight light water moderated lattices. Reasons for this close agreement are investigated here. By re-examining the effects of reflective and white cell boundary conditions in these calculations it is concluded that one major reason is the use of white boundary condition necessitated by the approximation of the two-dimensional reactor lattice cell by a one-dimensional one. (orig.) [de
A numerical method for two-dimensional anisotropic transport problem in cylindrical geometry
International Nuclear Information System (INIS)
Du Mingsheng; Feng Tiekai; Fu Lianxiang; Cao Changshu; Liu Yulan
1988-01-01
The authors deal with the triangular mesh-discontinuous finite element method for solving the time-dependent anisotropic neutron transport problem in two-dimensional cylindrical geometry. A prior estimate of the numerical solution is given. Stability is proved. The authors have computed a two dimensional anisotropic neutron transport problem and a Tungsten-Carbide critical assembly problem by using the numerical method. In comparision with DSN method and the experimental results obtained by others both at home and abroad, the method is satisfactory
An analytical solution for the two-group kinetic neutron diffusion equation in cylindrical geometry
International Nuclear Information System (INIS)
Fernandes, Julio Cesar L.; Vilhena, Marco Tullio; Bodmann, Bardo Ernst
2011-01-01
Recently the two-group Kinetic Neutron Diffusion Equation with six groups of delay neutron precursor in a rectangle was solved by the Laplace Transform Technique. In this work, we report on an analytical solution for this sort of problem but in cylindrical geometry, assuming a homogeneous and infinite height cylinder. The solution is obtained applying the Hankel Transform to the Kinetic Diffusion equation and solving the transformed problem by the same procedure used in the rectangle. We also present numerical simulations and comparisons against results available in literature. (author)
Energy Technology Data Exchange (ETDEWEB)
Edwards, David, E-mail: dej@kingcon.com [IJL Research Center, Newark, VT 05871 (United States)
2011-07-21
This paper is a review of multi-region FDM, a numerical technique for accurately determining electrostatic potentials in cylindrically symmetric geometries. Multi-region FDM can be thought of as the union of various individual elements: a single region FDM process: a method for algorithmic development; a method for auto creating a multi-region structure; the process for the relaxation of multi-region structures. Each element will be briefly described along with its integration into the multi-region relaxation process itself.
NRN, Removal-Diffusion for Squares and Cylindrical Geometry with Energy Transfer Matrix
International Nuclear Information System (INIS)
Olson, G.
1981-01-01
A - Nature of physical problem solved: A system of programmes using the NRN shield design method. NRN consists of the following programmes: 1) Data preparation programme NECO. 2) Multigroup removal programmes REBOX for box geometry and REMC for spherical and cylindrical geometries. 3) Multigroup diffusion - and slowing down programme NEDI. B - Method of solution: The NRN method presents a new approach in the formulation of removal-diffusion theory. The removal cross section is redefined and the slowing down between the multi-group diffusion equations is treated with a complete energy-transfer matrix rather than in an age theory approximation. CDC 3400 version was offered by Tesperhude (Gesellschaft fuer Kernenergieverwertung in Schiffbau und Schiffahrt MBH., Germany)
Quality of Slab Track Construction – Track Alignment Design and Track Geometry
Directory of Open Access Journals (Sweden)
Šestáková Janka
2015-05-01
Full Text Available The slab track superstructure design (without ballast is a perspective construction especially for building tunnels and bridges in the modernized sections of railway tracks in Slovakia. Monitoring of the structure described in this article is focused on the transition areas between standard structure with ballast and slab track construction.
Quality of Slab Track Construction - Track Alignment Design and Track Geometry
Šestáková, Janka
2015-05-01
The slab track superstructure design (without ballast) is a perspective construction especially for building tunnels and bridges in the modernized sections of railway tracks in Slovakia. Monitoring of the structure described in this article is focused on the transition areas between standard structure with ballast and slab track construction.
Energy Technology Data Exchange (ETDEWEB)
Zanette, Rodrigo [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Programa de Pós-Graduação em Matemática Aplicada; Petersen, Claudio Z.; Tavares, Matheus G., E-mail: rodrigozanette@hotmail.com, E-mail: claudiopetersen@yahoo.com.br, E-mail: matheus.gulartetavares@gmail.com [Universidade Federal de Pelotas (UFPEL), RS (Brazil). Programa de Pós-Graduação em Modelagem Matemática
2017-07-01
We describe in this work the application of the modified power method for solve the multigroup neutron diffusion eigenvalue problem in slab geometry considering two-dimensions for nuclear reactor global calculations. It is well known that criticality calculations can often be best approached by solving eigenvalue problems. The criticality in nuclear reactors physics plays a relevant role since establishes the ratio between the numbers of neutrons generated in successive fission reactions. In order to solve the eigenvalue problem, a modified power method is used to obtain the dominant eigenvalue (effective multiplication factor (K{sub eff})) and its corresponding eigenfunction (scalar neutron flux), which is non-negative in every domain, that is, physically relevant. The innovation of this work is solving the neutron diffusion equation in analytical form for each new iteration of the power method. For solve this problem we propose to apply the Finite Fourier Sine Transform on one of the spatial variables obtaining a transformed problem which is resolved by well-established methods for ordinary differential equations. The inverse Fourier transform is used to reconstruct the solution for the original problem. It is known that the power method is an iterative source method in which is updated by the neutron flux expression of previous iteration. Thus, for each new iteration, the neutron flux expression becomes larger and more complex due to analytical solution what makes propose that it be reconstructed through an polynomial interpolation. The methodology is implemented to solve a homogeneous problem and the results are compared with works presents in the literature. (author)
Finite differences versus finite elements in slab geometry, even-parity transport theory
International Nuclear Information System (INIS)
Miller, W.F. Jr.; Noh, T.
1993-01-01
There continues to be considerable interest in the application of the even-parity transport equation to problems of radiation transfer and neutron transport. The motivation for this interest arises from several potential advantages of this equation when compared with the more traditional first-order form of the equation. First, assuming that the scalar flux is of primary interest, the angular domain under consideration is one-half of that required for the first-order equation. Thus, for the same degree of accuracy, one would hopefully require substantiably fewer unknown values of the dependent variable to be determined. Secondly, the elliptic-like nature of the set of even-parity equations should allow certain parallel computer architectures to be used more readily. In a recent paper, it was shown that for neutron transport applications in slab geometry, finite differencing the even-parity equation on the cell edges yields algebraic equations with numerical properties that are superior to the traditional diamond difference approach. Specifically, a positive, second-order method with a rapidly convergent iteration approach emerged from cell-edge differencing. Additionally, for radiation transfer problems that are optically thick, it was shown that cell-edge differencing demonstrates better behavior than does diamond-differencing. However, some problems in accuracy could occur due to vacuum boundaries as well as at interfaces between very different types of material regions. These problems emerge from a boundary-layer analysis of the so called open-quotes thickclose quotes diffusion limit. For neutronics calculations, which are the subject of this paper, however, the open-quotes thickclose quotes diffusion limit analysis has little applicability, and the cell-edge differencing derived previously seems to have considerable promise. 13 refs., 2 figs., 3 tabs
Nodal integral method for the neutron diffusion equation in cylindrical geometry
International Nuclear Information System (INIS)
Azmy, Y.Y.
1987-01-01
The nodal methodology is based on retaining a higher a higher degree of analyticity in the process of deriving the discrete-variable equations compared to conventional numerical methods. As a result, extensive numerical testing of nodal methods developed for a wide variety of partial differential equations and comparison of the results to conventional methods have established the superior accuracy of nodal methods on coarse meshes. Moreover, these tests have shown that nodal methods are more computationally efficient than finite difference and finite-element methods in the sense that they require shorter CPU times to achieve comparable accuracy in the solutions. However, nodal formalisms and the final discrete-variable equations they produce are, in general, more complicated than their conventional counterparts. This, together with anticipated difficulties in applying the transverse-averaging procedure in curvilinear coordinates, has limited the applications of nodal methods, so far, to Cartesian geometry, and with additional approximations to hexagonal geometry. In this paper the authors report recent progress in deriving and numerically implementing a nodal integral method (NIM) for solving the neutron diffusion equation in cylindrical r-z geometry. Also, presented are comparisons of numerical solutions to two test problems with those obtained by the Exterminator-2 code, which indicate the superior accuracy of the nodal integral method solutions on much coarser meshes
The influence of triggers geometry upon the stiffness of cylindrical thin walled tubes
Soica, Adrian; Radu, Gheorghe N.
2014-06-01
Today's automobile manufacturers are increasingly using lightweight materials to reduce weight; these include plastics, composites, aluminium, magnesium alloys, and also new types of high strength steels. Many of these materials have limited strength or ductility, therefore in many cases the rupture being serious consequences during crashes, underscore Picketta et al. in their studies. Automotive structures must deform plastically in a short period of time, a few milliseconds, to absorb the crash energy in a controllable manner. It must be light and enable economically mass-production [1]. FE models rapidly gained acceptance among engineers. Many other factors facilitated the development of vehicle models by shell finite elements since most of the geometry of the structural surfaces was already on computer graphic files. Kee Poong Kim and Hoon Huh emphasize that the crashworthiness of each vehicle part needs to be evaluated at the initial stage of design for good performance of an assembled vehicle. As the dynamic behaviour of structural members is different from the static one, the crashworthiness of the vehicle structures has to be assessed by impact analysis. The paper analyzes the influence of trigger geometry upon the compression of thin-walled cylindrical tubes. Simulations performed on a simple model showed the dependence between triggers area and deformation times as well as the maximum deformations obtained for various speeds at which the simulations ware carried out. Likewise, the geometry of trigger leads to different results.
Li, B O; Sun, Hui; Zhou, Shenggao
The solute-solvent interface that separates biological molecules from their surrounding aqueous solvent characterizes the conformation and dynamics of such molecules. In this work, we construct a solvent fluid dielectric boundary model for the solvation of charged molecules and apply it to study the stability of a model cylindrical solute-solvent interface. The motion of the solute-solvent interface is defined to be the same as that of solvent fluid at the interface. The solvent fluid is assumed to be incompressible and is described by the Stokes equation. The solute is modeled simply by the ideal-gas law. All the viscous force, hydrostatic pressure, solute-solvent van der Waals interaction, surface tension, and electrostatic force are balanced at the solute-solvent interface. We model the electrostatics by Poisson's equation in which the solute-solvent interface is treated as a dielectric boundary that separates the low-dielectric solute from the high-dielectric solvent. For a cylindrical geometry, we find multiple cylindrically shaped equilibrium interfaces that describe polymodal (e.g., dry and wet) states of hydration of an underlying molecular system. These steady-state solutions exhibit bifurcation behavior with respect to the charge density. For their linearized systems, we use the projection method to solve the fluid equation and find the dispersion relation. Our asymptotic analysis shows that, for large wavenumbers, the decay rate is proportional to wavenumber with the proportionality half of the ratio of surface tension to solvent viscosity, indicating that the solvent viscosity does affect the stability of a solute-solvent interface. Consequences of our analysis in the context of biomolecular interactions are discussed.
MURLI, 1-D Flux, Reaction Rate in Cylindrical Geometry Thermal Reactor Lattice by Transport
International Nuclear Information System (INIS)
Huria, H.C.
1985-01-01
1 - Description of problem or function: MURLI is an integral transport theory code to calculate fluxes and reaction rates in one- dimensional cylindrical geometry lattice cells of a thermal reactor. For a specified buckling, it computes k-effective using few-group diffusion theory and a few-group collapsed set of Cross sections. The code can optionally be used to solve a first order differential equation for the number density of fissile, fertile and fission product nuclei as a function of time, and to recalculate fluxes, reaction rates and k-effective at different stages of burnup. A 27-group cross section data library is included. There are four pseudo-fission products each associated with the decay chains of plutonium and uranium isotopes in addition to Rh-105, Xe-135, Np-239, U-236, Am-241, Am-242 and Am-243. There is also data for one lumped pseudo-fission product. 2 - Method of solution: Multiple collision probabilities and escape probabilities are calculated for each cylindrical shell region assuming protons are born uniformly and isotropically over the entire region volume. The equations of integral transport theory can then be solved for neutron flux. The first order differential burnup equation is solved by a fourth order Runge-Kutta method. 3 - Restrictions on the complexity of the problem: There are maxima of 8 fissionable elements, 8 resonant elements, and 20 spatial regions
International Nuclear Information System (INIS)
Coffey, M.W.
1996-01-01
Due to their short coherence lengths and relatively large energy gaps, the high-transition temperature superconductors are very likely candidates as ultraclean materials at low temperature. This class of materials features significantly modified vortex dynamics, with very little dissipation at low temperature. The motion is then dominated by wave propagation, being in general nonlinear. Here two-dimensional vortex motion is investigated in the ultraclean regime for a superconductor described in cylindrical geometry. The small-amplitude limit is assumed, and the focus is on the long-wavelength limit. Results for both zero and nonzero Hall force are presented, with the effects of nonlocal vortex interaction and vortex inertia being included within London theory. Linear and nonlinear problems are studied, with a predisposition toward the more analytically tractable situations. For a nonlinear problem in 2+1 dimensions, the cylindrical Kadomtsev-Petviashvili equation is derived. Hall angle measurements on high-T c superconductors indicate the need to investigate the properties of such a completely integrable wave equation. copyright 1996 The American Physical Society
Yakubov, Vladislav; Xu, Lirong; Volinsky, Alex A.; Qiao, Lijie; Pan, De'an
2017-08-01
Trilayer Ni/PZT/Ni cylindrical magnetoelectric (ME) composites were prepared by electrodeposition, a process, which creates sub-millimeter raised edges due to current concentration near sharp points. The ME response in both axial and vertical modes was measured with the edges, with only outer edges removed, and with both outer and inner edges removed. The ME voltage coefficient improved at resonance by 40% and 147% without the edges in the vertical and axial modes, respectively. The observed improvements in three different samples were only present at the ME resonance and no changes were detected outside of the ME resonance. Mechanical quality factor at resonance also improved with no effect on the resonant frequency. Experimentally demonstrated minor geometry changes resulted in substantial ME improvement at resonant frequency. This study demonstrates device performance optimization. The observed effects have been attributed to improved vibrations in terms of decreased damping coefficient and enhanced vibration amplitude at resonance.
The nonuniform magnetohydrodynamic nature of the solar corona. III. Cylindrical geometry
International Nuclear Information System (INIS)
De ville, A.; Priest, E.R.
1989-01-01
The method developed by Priest in 1988 for modeling steady MHD disturbances in the solar corona is extended to a cylindrical geometry, which is more realistic for three-dimensional structures, such as plumes and coronal holes, which are observed in the corona. Both axial symmetric and nonaxial magnetic fields are treated. The basic characteristics of the axisymmetric solutions are found to be similar to the previous Cartesian case. Quantitatively, the interactions are stronger in the central region and weaker at the outer boundary. Pressure gradients are also found to be smaller. Solutions dependent on all three spatial variables exhibit an asymmetry because of the angular dependence. They depend upon the azimuthal magnetic field imposed at the coronal base. The solutions found in this paper may be useful in interpreting the physics of MHD interactions observed in numerical experiments and also in the solar atmosphere
Directory of Open Access Journals (Sweden)
Vladislav Yakubov
2017-08-01
Full Text Available Trilayer Ni/PZT/Ni cylindrical magnetoelectric (ME composites were prepared by electrodeposition, a process, which creates sub-millimeter raised edges due to current concentration near sharp points. The ME response in both axial and vertical modes was measured with the edges, with only outer edges removed, and with both outer and inner edges removed. The ME voltage coefficient improved at resonance by 40% and 147% without the edges in the vertical and axial modes, respectively. The observed improvements in three different samples were only present at the ME resonance and no changes were detected outside of the ME resonance. Mechanical quality factor at resonance also improved with no effect on the resonant frequency. Experimentally demonstrated minor geometry changes resulted in substantial ME improvement at resonant frequency. This study demonstrates device performance optimization. The observed effects have been attributed to improved vibrations in terms of decreased damping coefficient and enhanced vibration amplitude at resonance.
Electron Raman scattering in semiconductor quantum well wire of cylindrical ring geometry
International Nuclear Information System (INIS)
Betancourt-Riera, Re.; Betancourt-Riera, Ri.; Nieto Jalil, J. M.; Riera, R.
2015-01-01
We study the electron states and the differential cross section for an electron Raman scattering process in a semiconductor quantum well wire of cylindrical ring geometry. The electron Raman scattering developed here can be used to provide direct information about the electron band structures of these confinement systems. We assume that the system grows in a GaAs/Al 0.35 Ga 0.65 As matrix. The system is modeled by considering T = 0 K and also a single parabolic conduction band, which is split into a sub-band system due to the confinement. The emission spectra are discussed for different scattering configurations, and the selection rules for the processes are also studied. Singularities in the spectra are found and interpreted. (paper)
The Csub(N) method in cylindrical geometry and one-velocity theory
International Nuclear Information System (INIS)
Kavenoky, A.
1975-01-01
The Csub(N) method of solving the transport equation has been developed at Saclay during the last few years: its main advantage is that the computing time is independent of the size of the media considered. This method is based on a lemma proved by Placzek: an integral equation is provided for the angular flux at the boundaries of the media, its kernel is the infinite medium Green's function. The knowledge of the angular flux at the boundaries of the media allows the fluxes to be calculated at any point. The report is devoted to the application to classical problems in one velocity cylindrical geometry: albedo of the inner and outer problems, extrapolation length for the Milne problem, critical radius [fr
Lundh, Torbjörn; Suh, Ga-Young; DiGiacomo, Phillip; Cheng, Christopher
2018-03-03
Vascular morphology characterization is useful for disease diagnosis, risk stratification, treatment planning, and prediction of treatment durability. To quantify the dynamic surface geometry of tubular-shaped anatomic structures, we propose a simple, rigorous Lagrangian cylindrical coordinate system to monitor well-defined surface points. Specifically, the proposed system enables quantification of surface curvature and cross-sectional eccentricity. Using idealized software phantom examples, we validate the method's ability to accurately quantify longitudinal and circumferential surface curvature, as well as eccentricity and orientation of eccentricity. We then apply the method to several medical imaging data sets of human vascular structures to exemplify the utility of this coordinate system for analyzing morphology and dynamic geometric changes in blood vessels throughout the body. Graphical abstract Pointwise longitudinal curvature of a thoracic aortic endograft surface for systole and diastole, with their absolute difference.
International Nuclear Information System (INIS)
1982-01-01
1 - Description of problem or function: ONETRAN solves the one- dimensional multigroup transport equation in plane, cylindrical, spherical, and two-angle plane geometries. Both regular and adjoint, inhomogeneous and homogeneous (K-eff and eigenvalue searches) problems subject to vacuum, reflective, periodic, white, albedo or inhomogeneous boundary flux conditions are solved. General anisotropic scattering is allowed and anisotropic inhomogeneous sources are permitted. 2 - Method of solution: The discrete ordinates approximation for the angular variable is used with the diamond (central) difference approximation for the angular extrapolation in curved geometries. A linear discontinuous finite element representation for the angular flux in each spatial mesh cell is used. Negative fluxes are eliminated by a local set-to-zero and correct algorithm. Standard inner (within-group) iteration cycles are accelerated by system re-balance, coarse mesh re-balance, or Chebyshev acceleration. Outer iteration cycles are accelerated by coarse-mesh re-balance. 3 - Restrictions on the complexity of the problem: Variable dimensioning is used so that any combination of problem parameters leading to a container array less than MAXCOR can be accommodated. On CDC machines MAXCOR can be about 25 000 words and peripheral storage is used for most group-dependent data
International Nuclear Information System (INIS)
Agazzi, A.; Forti, G.; Vincenti, E.
1984-01-01
1 - Nature of physical problem solved: Purpose of the programmes is to study reactor dynamics, considering the variation of the spatial flux distribution. The two programmes COSTANZA-CYL and COSTANZA-AX, solve the kinetics diffusion equations in two groups and one dimension (plane geometry for COSTANZA-AX, radial geometry for COSTANZA-CYL). The neutronic calculation is coupled with the calculation of the heat transmission from the fuel to the cladding and to the coolant, and with the thermo-hydraulics of channels with forced circulation of liquid coolant. The geometry of fuel element and channel may be cylindrical or slab. Up to ten groups of delayed neutrons are allowed. Temperature feedback of fuel (Doppler) and coolant are considered independently and affect the nuclear constants. Control rod movement or diffused poison concentrations are simulated by externally imposed variations of the thermal absorption cross section in the different regions of the reactors. Inlet temperatures and mass flow in the coolant channels may be varied according to any externally given time table. 2 - Method of solution: The kinetic diffusion equations in two groups are solved by finite-difference method. 3 - Restrictions on the complexity of the problem: 10 concentric regions; 10 coolant channels; 10 groups of delayed neutrons
International Nuclear Information System (INIS)
Chapin, D.L.
1976-03-01
Differences in neutron fluxes and nuclear reaction rates in a noncircular fusion reactor blanket when analyzed in cylindrical and toroidal geometry are studied using Monte Carlo. The investigation consists of three phases--a one-dimensional calculation using a circular approximation to a hexagonal shaped blanket; a two-dimensional calculation of a hexagonal blanket in an infinite cylinder; and a three-dimensional calculation of the blanket in tori of aspect ratios 3 and 5. The total blanket reaction rate in the two-dimensional model is found to be in good agreement with the circular model. The toroidal calculations reveal large variations in reaction rates at different blanket locations as compared to the hexagonal cylinder model, although the total reaction rate is nearly the same for both models. It is shown that the local perturbations in the toroidal blanket are due mainly to volumetric effects, and can be predicted by modifying the results of the infinite cylinder calculation by simple volume factors dependent on the blanket location and the torus major radius
Solutions of diffusion equations in two-dimensional cylindrical geometry by series expansions
International Nuclear Information System (INIS)
Ohtani, Nobuo
1976-01-01
A solution of the multi-group multi-regional diffusion equation in two-dimensional cylindrical (rho-z) geometry is obtained in the form of a regionwise double series composed of Bessel and trigonometrical functions. The diffusion equation is multiplied by weighting functions, which satisfy the homogeneous part of the diffusion equation, and the products are integrated over the region for obtaining the equations to determine the fluxes and their normal derivatives at the region boundaries. Multiplying the diffusion equation by each function of the set used for the flux expansion, then integrating the products, the coefficients of the double series of the flux inside each region are calculated using the boundary values obtained above. Since the convergence of the series thus obtained is slow especially near the region boundaries, a method for improving the convergence has been developed. The double series of the flux is separated into two parts. The normal derivative at the region boundary of the first part is zero, and that of the second part takes the value which is obtained in the first stage of this method. The second part is replaced by a continuous function, and the flux is represented by the sum of the continuous function and the double series. A sample critical problem of a two-group two-region system is numerically studied. The results show that the present method yields very accurately the flux integrals in each region with only a small number of expansion terms. (auth.)
SIMULATIONS OF VISCOUS ACCRETION FLOW AROUND BLACK HOLES IN A TWO-DIMENSIONAL CYLINDRICAL GEOMETRY
Energy Technology Data Exchange (ETDEWEB)
Lee, Seong-Jae; Hyung, Siek [School of Science Education (Astronomy), Chungbuk National University, Chungbuk 28644 (Korea, Republic of); Chattopadhyay, Indranil; Kumar, Rajiv [ARIES, Manora Peak, Nainital-263002, Uttarakhand (India); Ryu, Dongsu, E-mail: seong@chungbuk.ac.kr [Department of Physics, School of Natural Sciences UNIST, Ulsan 44919 (Korea, Republic of)
2016-11-01
We simulate shock-free and shocked viscous accretion flows onto a black hole in a two-dimensional cylindrical geometry, where initial conditions were chosen from analytical solutions. The simulation code used the Lagrangian total variation diminishing plus remap routine, which enabled us to attain high accuracy in capturing shocks and to handle the angular momentum distribution correctly. The inviscid shock-free accretion disk solution produced a thick disk structure, while the viscous shock-free solution attained a Bondi-like structure, but in either case, no jet activity nor any quasi-periodic oscillation (QPO)-like activity developed. The steady-state shocked solution in the inviscid as well as in the viscous regime matched theoretical predictions well. However, increasing viscosity renders the accretion shock unstable. Large-amplitude shock oscillation is accompanied by intermittent, transient inner multiple shocks. This oscillation of the inner part of the disk is interpreted as the source of QPO in hard X-rays observed in micro-quasars. Strong shock oscillation induces strong episodic jet emission. The jets also show the existence of shocks, which are produced as one shell hits the preceding one. The periodicities of the jets and shock oscillation are similar; the jets for the higher viscosity parameter appear to be stronger and faster.
A plastic miniature x-ray emission spectrometer based on the cylindrical von Hamos geometry
International Nuclear Information System (INIS)
Mattern, B. A.; Seidler, G. T.; Haave, M.; Pacold, J. I.; Gordon, R. A.; Planillo, J.; Quintana, J.; Rusthoven, B.
2012-01-01
We present a short working distance miniature x-ray emission spectrometer (miniXES) based on the cylindrical von Hamos geometry. We describe the general design principles for the spectrometer and detail a specific implementation that covers Kβ and valence level emission from Fe. Large spatial and angular access to the sample region provides compatibility with environmental chambers, microprobe, and pump/probe measurements. The primary spectrometer structure and optic is plastic, printed using a 3-dimensional rapid-prototype machine. The spectrometer is inexpensive to construct and is portable; it can be quickly set up at any focused beamline with a tunable narrow bandwidth monochromator. The sample clearance is over 27 mm, providing compatibility with a variety of environment chambers. An overview is also given of the calibration and data processing procedures, which are implemented by a multiplatform user-friendly software package. Finally, representative measurements are presented. Background levels are below the level of the Kβ 2,5 valence emission, the weakest diagram line in the system, and photometric analysis of count rates finds that the instrument is performing at the theoretical limit.
Resistive effects on line-tied magnetohydrodynamic modes in cylindrical geometry
International Nuclear Information System (INIS)
Delzanno, Gian Luca; Evstatiev, E. G.; Finn, John M.
2007-01-01
An investigation of the effect of resistivity on the linear stability of line-tied magnetohydrodynamic (MHD) modes is presented in cylindrical geometry, based on the method recently developed in the paper by Evstatiev et al. [Phys. Plasmas 13, 072902 (2006)]. The method uses an expansion of the full solution of the problem in one-dimensional radial eigenfunctions. This method is applied to study sausage modes (m=0, m being the poloidal wavenumber), kink modes (m=1), and m=2 modes. All these modes can be resistively unstable. It is found that m≠0 modes can be unstable below the ideal MHD threshold due to resistive diffusion of the field lines, with growth rates proportional to resistivity. For these resistive modes, there is no indication of tearing, i.e., current sheets or boundary layers due to ideal MHD singularities. That is, resistivity acts globally on the whole plasma column and not in layers. Modes with m=0, on the other hand, can exist as tearing modes if the equilibrium axial magnetic field reverses sign within the plasma
Energy Technology Data Exchange (ETDEWEB)
Gheisari, R., E-mail: gheisari@pgu.ac.ir [Physics Department, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of); Nuclear Energy Research Center, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of); Firoozabadi, M. M.; Mohammadi, H. [Department of Physics, University of Birjand, Birjand 97175 (Iran, Islamic Republic of)
2014-01-15
A new idea to calculate ultracold neutron (UCN) production by using Monte Carlo simulation method to calculate the cold neutron (CN) flux and an analytical approach to calculate the UCN production from the simulated CN flux was given. A super-thermal source (UCN source) was modeled based on an arrangement of D{sub 2}O and solid D{sub 2} (sD{sub 2}). The D{sub 2}O was investigated as the neutron moderator, and sD{sub 2} as the converter. In order to determine the required parameters, a two-dimensional (2D) neutron balance equation written in Matlab was combined with the MCNPX simulation code. The 2D neutron-transport equation in cylindrical (ρ − z) geometry was considered for 330 neutron energy groups in the sD{sub 2}. The 2D balance equation for UCN and CN was solved using simulated CN flux as boundary value. The UCN source dimensions were calculated for the development of the next UCN source. In the optimal condition, the UCN flux and the UCN production rate (averaged over the sD{sub 2} volume) equal to 6.79 × 10{sup 6} cm{sup −2}s{sup −1} and 2.20 ×10{sup 5} cm{sup −3}s{sup −1}, respectively.
Linear Analyses of Magnetohydrodynamic Richtmyer-Meshkov Instability in Cylindrical Geometry
Bakhsh, Abeer
2018-05-13
We investigate the Richtmyer-Meshkov instability (RMI) that occurs when an incident shock impulsively accelerates the interface between two different fluids. RMI is important in many technological applications such as Inertial Confinement Fusion (ICF) and astrophysical phenomena such as supernovae. We consider RMI in the presence of the magnetic field in converging geometry through both simulations and analytical means in the framework of ideal magnetohydrodynamics (MHD). In this thesis, we perform linear stability analyses via simulations in the cylindrical geometry, which is of relevance to ICF. In converging geometry, RMI is usually followed by the Rayleigh-Taylor instability (RTI). We show that the presence of a magnetic field suppresses the instabilities. We study the influence of the strength of the magnetic field, perturbation wavenumbers and other relevant parameters on the evolution of the RM and RT instabilities. First, we perform linear stability simulations for a single interface between two different fluids in which the magnetic field is normal to the direction of the average motion of the density interface. The suppression of the instabilities is most evident for large wavenumbers and relatively strong magnetic fields strengths. The mechanism of suppression is the transport of vorticity away from the density interface by two Alfv ́en fronts. Second, we examine the case of an azimuthal magnetic field at the density interface. The most evident suppression of the instability at the interface is for large wavenumbers and relatively strong magnetic fields strengths. After the shock interacts with the interface, the emerging vorticity breaks up into waves traveling parallel and anti-parallel to the magnetic field. The interference as these waves propagate with alternating phase causing the perturbation growth rate of the interface to oscillate in time. Finally, we propose incompressible models for MHD RMI in the presence of normal or azimuthal magnetic
International Nuclear Information System (INIS)
Lee, Joo Hee
2006-02-01
There is growing interest in developing pebble bed reactors (PBRs) as a candidate of very high temperature gas-cooled reactors (VHTRs). Until now, most existing methods of nuclear design analysis for this type of reactors are base on old finite-difference solvers or on statistical methods. But for realistic analysis of PBRs, there is strong desire of making available high fidelity nodal codes in three-dimensional (r,θ,z) cylindrical geometry. Recently, the Analytic Function Expansion Nodal (AFEN) method developed quite extensively in Cartesian (x,y,z) geometry and in hexagonal-z geometry was extended to two-group (r,z) cylindrical geometry, and gave very accurate results. In this thesis, we develop a method for the full three-dimensional cylindrical (r,θ,z) geometry and implement the method into a code named TOPS. The AFEN methodology in this geometry as in hexagonal geometry is 'robus' (e.g., no occurrence of singularity), due to the unique feature of the AFEN method that it does not use the transverse integration. The transverse integration in the usual nodal methods, however, leads to an impasse, that is, failure of the azimuthal term to be transverse-integrated over r-z surface. We use 13 nodal unknowns in an outer node and 7 nodal unknowns in an innermost node. The general solution of the node can be expressed in terms of that nodal unknowns, and can be updated using the nodal balance equation and the current continuity condition. For more realistic analysis of PBRs, we implemented em Marshak boundary condition to treat the incoming current zero boundary condition and the partial current translation (PCT) method to treat voids in the core. The TOPS code was verified in the various numerical tests derived from Dodds problem and PBMR-400 benchmark problem. The results of the TOPS code show high accuracy and fast computing time than the VENTURE code that is based on finite difference method (FDM)
K-FIX, Transient 2 Phase Flow Hydrodynamic in 2-D Planar or Cylindrical Geometry, Eulerian Method
International Nuclear Information System (INIS)
Rivard, W. C.; Torrey, M. D.
1980-01-01
1 - Description of problem or function: The transient dynamics of two- dimensional, two-phase flow with interfacial exchange are calculated at all flow speeds. Each phase is described in terms of its own density, velocity, and temperature. Separate sets of field equations govern the gas and liquid phase dynamics. The six field equations for the two phases couple through mass, momentum, and energy exchange. 2 - Method of solution: The equations are solved using an Eulerian finite difference technique that implicitly couples the rates of phase transitions, momentum, and energy exchange to determination of the pressure, density, and velocity fields. The implicit solution is accomplished iteratively using a point relaxation technique without linearizing the equations, thus eliminating the need for numerous derivative terms. Solutions can be obtained in one and two space dimensions in plane geometry and in cylindrical geometry with axial symmetry and zero azimuthal velocity. Solutions in spherical geometry can also be obtained in one space dimension. The geometric region of interest is divided into many finite-sized, space-fixed zones called cells which form the computing mesh. In plane geometry the cells are rectangular cylinders, in cylindrical geometry they are toroids with rectangular cross section, and in spherical geometry they are spherical shells
Energy Technology Data Exchange (ETDEWEB)
Bedington, Robert, E-mail: r.bedington@nus.edu.sg; Kataria, Dhiren; Smith, Alan
2015-09-01
The CATS (Cylindrical And Tiny Spectrometer) electrostatic optics geometry features multiple nested cylindrical analysers to simultaneously measure multiple energies of electron and multiple energies of ion in a configuration that is targeted at miniaturisation and MEMS fabrication. In the prototyped model, two configurations of cylindrical analyser were used, featuring terminating side-plates that caused particle trajectories to either converge (C type) or diverge (D type) in the axial direction. Simulations show how these different electrode configurations affect the particle focussing and instrument parameters; C-type providing greater throughputs but D-type providing higher resolving powers. The simulations were additionally used to investigate unexpected plate spacing variations in the as-built model, revealing that the k-factors are most sensitive to the width of the inter-electrode spacing at its narrowest point. - Highlights: • A new nested cylindrical miniaturised electrostatic analyser geometry is described. • “Converging” (C) and “diverging” (D) type channel properties are investigated. • C channels are shown to have greater throughputs and D greater resolving powers. • Plate factors are shown to be sensitive to the minimum in inter-electrode spacing.
International Nuclear Information System (INIS)
Hadad, Kamal; Pirouzmand, Ahmad; Ayoobian, Navid
2008-01-01
This paper describes the application of a multilayer cellular neural network (CNN) to model and solve the time dependent one-speed neutron transport equation in slab geometry. We use a neutron angular flux in terms of the Chebyshev polynomials (T N ) of the first kind and then we attempt to implement the equations in an equivalent electrical circuit. We apply this equivalent circuit to analyze the T N moments equation in a uniform finite slab using Marshak type vacuum boundary condition. The validity of the CNN results is evaluated with numerical solution of the steady state T N moments equations by MATLAB. Steady state, as well as transient simulations, shows a very good comparison between the two methods. We used our CNN model to simulate space-time response of total flux and its moments for various c (where c is the mean number of secondary neutrons per collision). The complete algorithm could be implemented using very large-scale integrated circuit (VLSI) circuitry. The efficiency of the calculation method makes it useful for neutron transport calculations
International Nuclear Information System (INIS)
Barros, R. C.; Filho, H. A.; Platt, G. M.; Oliveira, F. B. S.; Militao, D. S.
2009-01-01
Coarse-mesh numerical methods are very efficient in the sense that they generate accurate results in short computational time, as the number of floating point operations generally decrease, as a result of the reduced number of mesh points. On the other hand, they generate numerical solutions that do not give detailed information on the problem solution profile, as the grid points can be located considerably away from each other. In this paper we describe two analytical reconstruction schemes for the coarse-mesh solution generated by the spectral nodal method for neutral particle discrete ordinates (S N ) transport model in slab geometry. The first scheme we describe is based on the analytical reconstruction of the coarse-mesh solution within each discretization cell of the spatial grid set up on the slab. The second scheme is based on the angular reconstruction of the discrete ordinates solution between two contiguous ordinates of the angular quadrature set used in the S N model. Numerical results are given so we can illustrate the accuracy of the two reconstruction schemes, as described in this paper. (authors)
Rodriguez, Alejandro W; Ilic, Ognjen; Bermel, Peter; Celanovic, Ivan; Joannopoulos, John D; Soljačić, Marin; Johnson, Steven G
2011-09-09
We demonstrate the possibility of achieving enhanced frequency-selective near-field radiative heat transfer between patterned (photonic-crystal) slabs at designable frequencies and separations, exploiting a general numerical approach for computing heat transfer in arbitrary geometries and materials based on the finite-difference time-domain method. Our simulations reveal a tradeoff between selectivity and near-field enhancement as the slab-slab separation decreases, with the patterned heat transfer eventually reducing to the unpatterned result multiplied by a fill factor (described by a standard proximity approximation). We also find that heat transfer can be further enhanced at selective frequencies when the slabs are brought into a glide-symmetric configuration, a consequence of the degeneracies associated with the nonsymmorphic symmetry group.
Analysis and evaluation of zig-zag slab laser amplifier with optical diamond geometry
International Nuclear Information System (INIS)
Matsumoto, Osamu; Yasuhara, Ryo; Kanabe, Tadashi
2007-01-01
In this paper, we describe the development of a high-average-power solid-state laser system and the derivation of equations for the amplification of a laser beam. This laser system is capable of generating an output energy of 10J per pulse at a wavelength of 1,053nm in a 10 Hz operation for scientific and industrial applications. The main amplifier of our system is a laser-diode-pumped solid-state amplifier. A water-cooled Nd:glass slab is pumped with two 803 nm AlGaAs laser-diode modules. The laser beam propagates through zig-zag optical paths four times and is amplified. To estimate laser output energy, we have derived and evaluated equations for the amplification of the laser beam, and designed and constructed a laser system based on the calculated results. Experimental results reveal an output energy of 10.6 J at 1 Hz, which closely fits the results calculated using the derived equations. (author)
Rational function approximation method for discrete ordinates problems in slab geometry
International Nuclear Information System (INIS)
Leal, Andre Luiz do C.; Barros, Ricardo C.
2009-01-01
In this work we use rational function approaches to obtain the transfer functions that appear in the spectral Green's function (SGF) auxiliary equations for one-speed isotropic scattering SN equations in one-dimensional Cartesian geometry. For this task we use the computation of the Pade approximants to compare the results with the standard SGF method's applied to deep penetration problems in homogeneous domains. This work is a preliminary investigation of a new proposal for handling leakage terms that appear in the two transverse integrated one-dimensional SN equations in the exponential SGF method (SGF-ExpN). Numerical results are presented to illustrate the rational function approximation accuracy. (author)
International Nuclear Information System (INIS)
1981-01-01
IHI has designed and constructed the CCTF at JAERI to be used in the safety analysis research on the loss of coolant accident in a PWR plant. This test facility is planned so that reflood phenomenon in the PWR plant (a phenomenon is that the bared and overheated core is reflooded by the emergency core cooling system when the coolant loss accident occurred) is simulated under various test conditions. The CCTF is the largest-scale test plant in the world, composed of approximately 2000 simulated fuel rods (electric heaters), 1 simulated pressure vessel, 4 primary cooling loops, 2 simulated steam generators, emergency core cooling system, and so on. The test conditions are controlled, and the test steps are sequentially progressed by the computing system, and test data are collected by the data acquisition system. Furthermore, IHI is now designing and constructing the SCTF in accordance with the JAERI research plan. The SCTF is similar to the CCTF in scale. Main feature of the SCTF is the form of the simulated core and the simulated pressure vessel, which is of slab construction to be representative of the radial section of the PWR reactor. Reliable and various data for safety analysis are expected by the CCTF and the SCTF. (author)
Laurencin, M.; Graindorge, D.; Klingelhoefer, F.; Marcaillou, B.; Evain, M.
2018-06-01
In subduction zones, the 3D geometry of the plate interface is one of the key parameters that controls margin tectonic deformation, interplate coupling and seismogenic behavior. The North American plate subducts beneath the convex Northern Lesser Antilles margin. This convergent plate boundary, with a northward increasing convergence obliquity, turns into a sinistral strike-slip limit at the northwestern end of the system. This geodynamic context suggests a complex slab geometry, which has never been imaged before. Moreover, the seismic activity and particularly the number of events with thrust focal mechanism compatible with subduction earthquakes, increases northward from the Barbuda-Anguilla segment to the Anguilla-Virgin Islands segment. One of the major questions in this area is thus to analyze the influence of the increasing convergence obliquity and the slab geometry onto tectonic deformation and seismogenic behavior of the subduction zone. Based on wide-angle and multichannel reflection seismic data acquired during the Antithesis cruises (2013-2016), we decipher the deep structure of this subduction zone. Velocity models derived from wide-angle data acquired across the Anegada Passage are consistent with the presence of a crust of oceanic affinity thickened by hotspot magmatism and probably affected by the Upper Cretaceous-Eocene arc magmatism forming the 'Great Arc of the Caribbean'. The slab is shallower beneath the Anguilla-Virgin Islands margin segment than beneath the Anguilla-Barbuda segment which is likely to be directly related to the convex geometry of the upper plate. This shallower slab is located under the forearc where earthquakes and partitioning deformations increase locally. Thus, the shallowing slab might result in local greater interplate coupling and basal friction favoring seismic activity and tectonic partitioning beneath the Virgin Islands platform.
International Nuclear Information System (INIS)
Lee, Jaejun; Cho, Namzin
2007-01-01
Most existing methods of nuclear design analysis for pebble bed reactors (PBRs) are based on old finite difference solvers or on statistical methods. These methods require very long computer times. Therefore, there is strong desire of making available high fidelity coarse-mesh nodal computer codes. Recently, we extended the analytic function expansion nodal (AFEN) method developed quite extensively in Cartesian (x,y,z) geometry and in hexagonal-z geometry to the treatment of the full three dimensional cylindrical (r,θ,z) geometry for pebble bed reactors(PBRs). The AFEN methodology in this geometry as in hexagonal geometry is 'robust', due to the unique feature of the AFEN method that it does not use the transverse integration. This paper presents an acceleration scheme based on the coarse-group rebalance (CGR) concept and provides test results verifying the method and its implementation in the TOPS code. Also, we implemented discontinuity factors in the TOPS code and tested on benchmark problems. The TOPS results are in excellent agreement with those of the VENTURE code, using significantly less computer time
Energy Technology Data Exchange (ETDEWEB)
Oliva, Amaury M.; Filho, Hermes A.; Silva, Davi M.; Garcia, Carlos R., E-mail: aoliva@iprj.uerj.br, E-mail: halves@iprj.uerj.br, E-mail: davijmsilva@yahoo.com.br, E-mail: cgh@instec.cu [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Instituto Politecnico. Departamento de Modelagem Computacional; Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), La Habana (Cuba)
2017-07-01
In this paper, we propose a numerical methodology for the development of a method of the spectral nodal class that will generate numerical solutions free from spatial truncation errors. This method, denominated Spectral Deterministic Method (SDM), is tested as an initial study of the solutions (spectral analysis) of neutron transport equations in the discrete ordinates (S{sub N}) formulation, in one-dimensional slab geometry, multigroup approximation, with linearly anisotropic scattering, considering homogeneous and heterogeneous domains with fixed source. The unknowns in the methodology are the cell-edge, and cell average angular fluxes, the numerical values calculated for these quantities coincide with the analytic solution of the equations. These numerical results are shown and compared with the traditional ne- mesh method Diamond Difference (DD) and the coarse-mesh method spectral Green's function (SGF) to illustrate the method's accuracy and stability. The solution algorithms problems are implemented in a computer simulator made in C++ language, the same that was used to generate the results of the reference work. (author)
Two Step Procedure Using a 1-D Slab Spectral Geometry in a Pebble Bed Reactor Core Analysis
International Nuclear Information System (INIS)
Lee, Hyun Chul; Kim, Kang Seog; Noh, Jae Man; Joo, Hyung Kook
2005-01-01
A strong spectral interaction between the core and the reflector has been one of the main concerns in the analysis of pebble bed reactor cores. To resolve this problem, VSOP adopted iteration between the spectrum calculation in a spectral zone and the global core calculation. In VSOP, the whole problem domain is divided into many spectral zones in which the fine group spectrum is calculated using bucklings for fast groups and albedos for thermal groups from the global core calculation. The resulting spectrum in each spectral zone is used to generate broad group cross sections of the spectral zone for the global core calculation. In this paper, we demonstrate a two step procedure in a pebble bed reactor core analysis. In the first step, we generate equivalent cross sections from a 1-D slab spectral geometry model with the help of the equivalence theory. The equivalent cross sections generated in this way include the effect of the spectral interaction between the core and the reflector. In the second step, we perform a diffusion calculation using the equivalent cross sections generated in the first step. A simple benchmark problem derived from the PMBR-400 Reactor was introduced to verify this approach. We compared the two step solutions with the Monte Carlo (MC) solutions for the problem
International Nuclear Information System (INIS)
Chavda, L.K.
1978-01-01
Approximate analytic solutions to the self-similar equations of gas dynamics for a plasma, treated as an ideal gas with specific heat ratio γ=5/3 are obtained for the implosion and subsequent reflection of various types of shock sequences in spherical and cylindrical geometries. This is based on the lowest-order polynomial approximation in the reduced fluid velocity, for a suitable nonlinear function of the sound velocity and the fluid velocity. However, the method developed here is powerful enough to be extended analytically to higher order polynomial approximations, to obtain successive approximations to the exact self-similar solutions. Also obtained, for the first time, are exact asymptotic solutions, in analytic form, for the reflected shocks. Criteria are given that may enable one to make a choice between the two geometries for maximising compression or temperature of the gas. These solutions should be useful in the study of inertial confinement of a plasma. (author)
International Nuclear Information System (INIS)
Slipicevic, K.
1968-12-01
Following a review of the existing theories od resonance absorption this thesis includes a new approach for calculating the effective resonance integral of absorbed neutrons, new approximate formula for the penetration factor, an analysis of the effective resonance integral and the correction of the resonance integral taking into account the interference of potential and resonance dissipation. A separate chapter is devoted to calculation of the effective resonance integral for the regular reactor lattice with cylindrical fuel elements
Olivieri, Giorgia; Parry, Krista M.; Powell, Cedric J.; Tobias, Douglas J.
2017-01-01
Ion spatial distributions at the aqueous-air/vacuum interface are accessible by energy-dependent X-ray photoelectron spectroscopy (XPS). Here we quantify the difference between a flat surface and a cylindrical shaped microjet on the energy-dependent information depth of the XPS experiment and on the simulated photoelectron intensities using solutions of pure water and of 1 mol/L NaI as examples. PMID:28203664
International Nuclear Information System (INIS)
Amouyal, A.; Tariel, H.
1966-01-01
Code name: January 1 st SCEA 011S. 2) Computer: IBM 7094; Programme system: Fortran II, 2 nd version. 3) Nature of the problem: resolution of cell problems with one space variable (planar, spherical and cylindrical geometries) and with one energy group, with isotropic sources in the double P n approximation (DP 1 and DP 3 approximation in planar and spherical geometries, DP 1 and DP 2 in cylindrical geometry). 4) Method used: the differential equations with limiting conditions are transformed into differential system with initial conditions which are integrated by a separate-step method. 5) Restrictions: number of physical media [fr
Khan, Farman U; Qamar, Shamsul
2017-05-01
A set of analytical solutions are presented for a model describing the transport of a solute in a fixed-bed reactor of cylindrical geometry subjected to the first (Dirichlet) and third (Danckwerts) type inlet boundary conditions. Linear sorption kinetic process and first-order decay are considered. Cylindrical geometry allows the use of large columns to investigate dispersion, adsorption/desorption and reaction kinetic mechanisms. The finite Hankel and Laplace transform techniques are adopted to solve the model equations. For further analysis, statistical temporal moments are derived from the Laplace-transformed solutions. The developed analytical solutions are compared with the numerical solutions of high-resolution finite volume scheme. Different case studies are presented and discussed for a series of numerical values corresponding to a wide range of mass transfer and reaction kinetics. A good agreement was observed in the analytical and numerical concentration profiles and moments. The developed solutions are efficient tools for analyzing numerical algorithms, sensitivity analysis and simultaneous determination of the longitudinal and transverse dispersion coefficients from a laboratory-scale radial column experiment. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
International Nuclear Information System (INIS)
Menezes, Welton A.; Filho, Hermes Alves; Barros, Ricardo C.
2014-01-01
Highlights: • Fixed-source S N transport problems. • Energy multigroup model. • Anisotropic scattering. • Slab-geometry spectral nodal method. - Abstract: A generalization of the spectral Green’s function (SGF) method is developed for multigroup, fixed-source, slab-geometry discrete ordinates (S N ) problems with anisotropic scattering. The offered SGF method with the one-node block inversion (NBI) iterative scheme converges numerical solutions that are completely free from spatial truncation errors for multigroup, slab-geometry S N problems with scattering anisotropy of order L, provided L < N. As a coarse-mesh numerical method, the SGF method generates numerical solutions that generally do not give detailed information on the problem solution profile, as the grid points can be located considerably away from each other. Therefore, we describe in this paper a technique for the spatial reconstruction of the coarse-mesh solution generated by the multigroup SGF method. Numerical results are given to illustrate the method’s accuracy
Chang, Y.; Warren, L. M.; Prieto, G. A.
2015-12-01
In the northern Nazca subduction zone, the Nazca plate is subducting to the east beneath the South American Plate. At ~5.6ºN, the subducting plate has a 240-km east-west offset associated with a slab tear, called the Caldas tear, that separates the northern and southern segments. Our study seeks to better define the slab geometry and deformation in the southern segment, which has a high rate of intermediate-depth earthquakes (50-300 km) between 3.6ºN and 5.2ºN in the Cauca cluster. From Jan 2010 to Mar 2014, 228 intermediate-depth earthquakes in the Cauca cluster with local magnitude Ml 2.5-4.7 were recorded by 65 seismic stations of the Colombian National Seismic Network. We review and, if necessary, adjust the catalog P and S wave arrival picks. We use the travel times to relocate the earthquakes using a double difference relocation method. For earthquakes with Ml ≥3.8, we also use waveform modeling to compute moment tensors . The distribution of earthquake relocations shows an ~15-km-thick slab dipping to the SE. The dip angle increases from 20º at the northern edge of the cluster to 38º at the southern edge. Two concentrated groups of earthquakes extend ~40 km vertically above the general downdip trend, with a 20 km quiet gap between them at ~100 km depth. The earthquakes in the general downdip seismic zone have downdip compressional axes, while earthquakes close to the quiet gap and in the concentrated groups have an oblique component. The general decrease in slab dip angle to the north may be caused by mantle flow through the Caldas tear. The seismicity gap in the slab may be associated with an active deformation zone and the concentrated groups of earthquakes with oblique focal mechanisms could be due to a slab fold.
Energy Technology Data Exchange (ETDEWEB)
Watteau, J H [Commissariat a l' Energie Atomique, Limeil-Brevannes (France). Centre d' Etudes
1968-03-01
The plasma of a non-cylindrical z discharge is accumulated in the centre of a cusp geometry and then captured and confined by the rising cusp magnetic field. The cusp geometry is produced by two identical coaxial coils the currents of which are equal but in opposite directions. Stability and confinement properties of this zero minimum B geometry are recalled; in particular it is shown (the coils cross section being supposed punctual) that the magnetic well depth of the configuration without plasma is maximum for an optimum coils distance. Two modes of confinement are observed experimentally : - a collisional mode for which the plasma confinement is limited to 10 {mu}sec (temperature 5 eV, density 7 x 10{sup 16} cm{sup -3}) as a result of the gradual interpenetration of the plasma and of the magnetic field. - a collisionless mode (temperature 40 eV) where the radial leak thickness is of the order of the ion cyclotron radius. Plasma accumulation occurs even without confinement and is due to the non-cylindrical shape of the discharge chamber. The two-dimensional snow-plough model gives good account of the discharge dynamics. A comparison is made with plasma focus experiments: in particular experimental conditions (deuterium, pressure 1 torr,energy 3 kJ, current 100 kA) a 10{sup 7} neutron yield is detected which appears to be connected with the unstable behavior of the discharge. (authors) [French] Le plasma d'une decharge lineaire non-cylindrique s'accumule au centre d'une geometrie magnetique cuspidee ou il est capture et confine par l'induction croissante de la geometrie. On rappelle les proprietes de stabilite et de confinement de la geometrie cuspidee, geometrie a champ minimum nul produite par deux spires identiques, coaxiales et parcourues par des courants egaux et opposes; on montre en particulier que pour des spires de section ponctuelle la profondeur du puits magnetique de la geometrie sans plasma est maximum pour une distance optimum des spires. Deux
Thermal neutron absorption cross-section for small samples (experiments in cylindrical geometry)
International Nuclear Information System (INIS)
Czubek, J.A.; Drozdowicz, K.; Igielski, A.; Krynicka-Drozdowicz, E.; Woznicka, U.
1982-01-01
Measurement results for thermal neutron macroscopic absorption cross-sections Σsub(a)1 when applying the cylindrical sample-moderator system are presented. Experiments for liquid (water solutions of H 3 BO 3 ) and solid (crushed basalts) samples are reported. Solid samples have been saturated with the H 3 BO 3 ''poisoning'' solution. The accuracy obtained for the determination of the absorption cross-section of the solid material was σ(Σsub(ma))=(1.2+2.2) c.u. in the case when porosity was measured with the accuracy of σ(phi)=0.001+0.002. The dispersion of the Σsub(ma) data obtained for basalts (taken from different quarries) was higher than the accuracy of the measurement. All experimental data for the fundamental decay constants lambda 0 together with the whole information about the samples are given. (author)
Thermoelastic buckling of plates in a cylindrical geometry against an elastic back support
International Nuclear Information System (INIS)
Simmons, L.D.; Wierman, R.W.
1980-01-01
A plate which is fixed at its edges to a strong edge support structure will develop large compressive stresses when heated from ambient temperature more rapidly than the support structure. Determining the response of the plate to this situation requires stability analysis to ascertain whether the plate might buckle, or whether the constrained thermal expansion will lead to compressive stresses exceeding the yield point because it did not buckle. A special case is considered here, both analytically and experimentally, in which the plate is curved slightly into a cylindrical shape and the convex face of the plate is against a supporting surface. This case is more complex because the buckling mode will be a harmonic rather than the fundamental mode which is usually encountered
Energy Technology Data Exchange (ETDEWEB)
Fernandes, Julio Cesar L.; Vilhena, Marco Tullio, E-mail: julio.lombaldo@ufrgs.b, E-mail: vilhena@pq.cnpq.b [Universidade Federal do Rio Grande do Sul (DMPA/UFRGS), Porto Alegre, RS (Brazil). Dept. de Matematica Pura e Aplicada. Programa de Pos Graduacao em Matematica Aplicada; Borges, Volnei; Bodmann, Bardo Ernest, E-mail: bardo.bodmann@ufrgs.b, E-mail: borges@ufrgs.b [Universidade Federal do Rio Grande do Sul (PROMEC/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica
2011-07-01
The principal idea of this work, consist on formulate an analytical method to solved problems for diffusion of neutrons with isotropic scattering in one-dimensional cylindrical geometry. In this area were develop many works that study the same problem in different system of coordinates as well as cartesian system, nevertheless using numerical methods to solve the shielding problem. In view of good results in this works, we starting with the idea that we can represent a source in the origin of the cylindrical system by a Delta Dirac distribution, we describe the physical modeling and solved the neutron diffusion equation inside of cylinder of radius R. For the case of transport equation, the formulation of discrete ordinates S{sub N} consists in discretize the angular variables in N directions and in using a quadrature angular set for approximate the sources of scattering, where the Diffusion equation consist on S{sub 2} approximated transport equation in discrete ordinates. We solved the neutron diffusion equation with an analytical form by the finite Hankel transform. Was presented also the build-up factor for the case that we have neutron flux inside the cylinder. (author)
International Nuclear Information System (INIS)
Fernandes, Julio Cesar L.; Vilhena, Marco Tullio; Borges, Volnei; Bodmann, Bardo Ernest
2011-01-01
The principal idea of this work, consist on formulate an analytical method to solved problems for diffusion of neutrons with isotropic scattering in one-dimensional cylindrical geometry. In this area were develop many works that study the same problem in different system of coordinates as well as cartesian system, nevertheless using numerical methods to solve the shielding problem. In view of good results in this works, we starting with the idea that we can represent a source in the origin of the cylindrical system by a Delta Dirac distribution, we describe the physical modeling and solved the neutron diffusion equation inside of cylinder of radius R. For the case of transport equation, the formulation of discrete ordinates S N consists in discretize the angular variables in N directions and in using a quadrature angular set for approximate the sources of scattering, where the Diffusion equation consist on S 2 approximated transport equation in discrete ordinates. We solved the neutron diffusion equation with an analytical form by the finite Hankel transform. Was presented also the build-up factor for the case that we have neutron flux inside the cylinder. (author)
Litvin, Faydor L.; Nava, Alessandro; Fan, Qi; Fuentes, Alfonso
2002-01-01
New geometry of face worm gear drives with conical and cylindrical worms is proposed. The generation of the face worm-gear is based on application of a tilted head-cutter (grinding tool) instead of application of a hob applied at present. The generation of a conjugated worm is based on application of a tilted head-cutter (grinding tool) as well. The bearing contact of the gear drive is localized and is oriented longitudinally. A predesigned parabolic function of transmission errors for reduction of noise and vibration is provided. The stress analysis of the gear drive is performed using a three-dimensional finite element analysis. The contacting model is automatically generated. The developed theory is illustrated with numerical examples.
Yager-Elorriaga, D. A.; Steiner, A. M.; Patel, S. G.; Jordan, N. M.; Lau, Y. Y.; Gilgenbach, R. M.
2015-11-01
In this work, we describe a technique for fabricating ultrathin foils in cylindrical geometry for liner-plasma implosion experiments using sub-MA currents. Liners are formed by wrapping a 400 nm, rectangular strip of aluminum foil around a dumbbell-shaped support structure with a non-conducting center rod, so that the liner dimensions are 1 cm in height, 6.55 mm in diameter, and 400 nm in thickness. The liner-plasmas are imploded by discharging ˜600 kA with ˜200 ns rise time using a 1 MA linear transformer driver, and the resulting implosions are imaged four times per shot using laser-shadowgraphy at 532 nm. This technique enables the study of plasma implosion physics, including the magneto Rayleigh-Taylor, sausage, and kink instabilities on initially solid, imploding metallic liners with university-scale pulsed power machines.
International Nuclear Information System (INIS)
Finn, J.M.
1995-01-01
A cylindrical model with finite beta having an external resonant ideal magnetohydrodynamic instability has been constructed. This resonant mode has a mode rational surface, where the safety factor q equals m/n, within the plasma. In this model, the perturbed radial magnetic field for the ideal mode is nonzero between the mode rational surface and the wall, even though it must vanish at the mode rational surface. This property of the mode is in common with the toroidal external kink. Results are presented showing that in the parameter range for which this ideal mode is stable with a conducting wall but unstable with the wall at infinity, a resistive wall mode persists. However, in the presence of plasma resistivity in a resistive layer about the mode rational surface, this resistive wall mode can be stabilized by a plasma rotation frequency of order a nominal resistive instability growth rate. Furthermore, the stabilization occurs in a large gap in wall position or beta. It is also shown that for the ideal resonant mode, as well as resistive plasma modes and nonresonant ideal plasma modes, there is a maximum value of plasma rotation above which there is no stability gap. Discussions are presented suggesting that these properties may hold for the toroidal external kink. copyright 1995 American Institute of Physics
A piezo-resistive graphene strain sensor with a hollow cylindrical geometry
Energy Technology Data Exchange (ETDEWEB)
Nakamura, Atsushi, E-mail: nakamura.atsushi@ipc.shizuoka.ac.jp [Graduate School of Integrated Science and Technology, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan); Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan); Hamanishi, Toshiki [Graduate School of Integrated Science and Technology, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan); Kawakami, Shotaro [Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan); Takeda, Masanori [Graduate School of Integrated Science and Technology, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan); Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan)
2017-05-15
Highlights: • A hollow tubing graphene fiber was synthesized from CVD-grown graphene on Ni wire. • The strain sensor showed the gauge factor 34.3–48.9 at 8% tensile strain. • The TGF sensors performed a writing finger motion assessment. - Abstract: We propose a resistance-type strain sensor consists of hollow tubing graphene fibers (TGFs) with dimethylpolysiloxane (PDMS) coating for millimeters-scale strain/bending detection applications. The TGFs were synthesized via graphene films grown on Ni wire by chemical vapor deposition (CVD). The TGFs are fundamentally folded continuous few-layered graphene films without edges maintained cylindrical tube supported by PDMS coating. Sensing properties were studied comparing with a multi-wall carbon nanotube (MWCNT)/PDMS composites (CNTCs) and the mechanism were discussed. In terms of the gauge factor, the sensor made of TGF is estimated to be in the range of 34.3–48.9 against 8% tensile strain. For a feasibility study, we demonstrate the human finger monitoring by means of bending angle detection on a finger joint.
International Nuclear Information System (INIS)
Schnedermann, E.; Heinz, U.
1991-01-01
Relativistic hydrodynamics has a long tradition of application to high energy collisions from e + e - to AA. A new way within the hydrodynamical environment is presented to compute the global expansion characteristics of the reaction zone. The method consists of integrating the hydrodynamical equations in a cylindrically symmetric region assuming specific thermal and velocity profiles to obtain global conservation laws from the local ones. Monitoring these, the system may be followed from its hot and dense initial state until freeze-out, where particle spectra can be computed and compared to experiments. By varying the initial conditions, both the rapidity distribution and the transverse momentum spectrum of pions from NA35 200 GeV/A S+S central collisions can be fitted and thus information gained about the early stages of the collision. As a further perspective, the method provides a framework within which hydrodynamical effects on the particle spectra can be discussed. It furthermore has the advantage to be numerically orders of magnitude faster than traditional local hydrodynamics. (author) 13 refs.; 4 figs.; 1 tab
Optimization of Orifice Geometry for Cross-Flow Mixing in a Cylindrical Duct
Kroll, J. T.; Sowa, W. A.; Samuelsen, G. S.
1996-01-01
Mixing of gaseous jets in a cross-flow has significant applications in engineering, one example of which is the dilution zone of a gas turbine combustor. Despite years of study, the design of the jet injection in combustors is largely based on practical experience. The emergence of NO(x) regulations for stationary gas turbines and the anticipation of aero-engine regulations requires an improved understanding of jet mixing as new combustor concepts are introduced. For example, the success of the staged combustor to reduce the emission of NO(x) is almost entirely dependent upon the rapid and complete dilution of the rich zone products within the mixing section. It is these mixing challenges to which the present study is directed. A series of experiments was undertaken to delineate the optimal mixer orifice geometry. A cross-flow to core-flow momentum-flux ratio of 40 and a mass flow ratio of 2.5 were selected as representative of a conventional design. An experimental test matrix was designed around three variables: the number of orifices, the orifice length-to- width ratio, and the orifice angle. A regression analysis was performed on the data to arrive at an interpolating equation that predicted the mixing performance of orifice geometry combinations within the range of the test matrix parameters. Results indicate that the best mixing orifice geometry tested involves eight orifices with a long-to-short side aspect ratio of 3.5 at a twenty-three degree inclination from the center-line of the mixing section.
Scaling Laws for Unstable Interfaces Driven by Strong Shocks in Cylindrical Geometry
International Nuclear Information System (INIS)
Zhang, Q.; Graham, M.J.; Graham, M.J.
1997-01-01
The Richtmyer-Meshkov (RM) instability is an interfacial interface between two fluids of different densities driven by shock waves and plays an important role in the studies of inertial confinement fusion and of supernovas. So far, most of the studies are for RM unstable interfaces driven by weak or intermediate shocks in planar geometry. For experiments conducted at the Nova laser, the unstable material interface is accelerated by very strong shocks. In this Letter, we present scaling laws for the RM unstable interface driven by strong imploding and exploding shocks. copyright 1997 The American Physical Society
Resolution of the steady state transport equation for Lagrangian geometry with cylindrical symmetry
International Nuclear Information System (INIS)
Samba, G.
1983-05-01
The purpose of this work is to solve the steady state transport equation for (r, z) geometries given by hydrodynamics calculations. The discontinuous finite element method for the space variables (r, z) provides a stable scheme which satisfies the particle balance equation. We are able to sweep cells for each direction over the mesh to have an explicit scheme. The graph theory provides a very efficient algorithm to compute this ordering array. Previously, we must divide all the quadrilaterals into two triangles to get only convex cells. Thus, we get a fast, vectorized calculation which gives a good accuracy on very distorted meshes [fr
Thermal compatibility of dental ceramic systems using cylindrical and spherical geometries
DeHoff, Paul H.; Barrett, Allyson A.; Lee, Robert B.; Anusavice, Kenneth J.
2009-01-01
Objective To test the hypothesis that bilayer ceramic cylinders and spheres can provide valid confirmation of thermal incompatibility stresses predicted by finite element analyses. Methods A commercial core ceramic and an experimental core ceramic were used to fabricate open-ended cylinders and core ceramic spheres. The core cylinders and spheres were veneered with one of four commercial dental ceramics representing four thermally compatible groups and four thermally incompatible groups. Axisymmetric thermal and viscoelastic elements in the ANSYS finite element program were used to calculate temperatures and stresses for each geometry and ceramic combination. This process required a transient heat transfer analysis for each combination to determine input temperatures for the structural model. Results After fabrication, each specimen was examined visually using fiberoptic transillumination for evidence of cracking. There were 100% failures of the thermally incompatible cylinders while none of the thermally compatible combinations failed. Among the spheres, 100% of the thermally incompatible systems failed, 16% of one of the thermally compatible systems failed, and none of the remaining compatible combinations failed. The calculated stress values were in general agreement with the experimental observations, i.e., low residual stresses for the specimens that did not fail and high residual stresses for the specimens that did fail. Significance Simple screening geometries can be used to identify highly incompatible ceramic combinations, but they do not identify marginally incompatible systems. PMID:17949805
3D geometry measurement of hot cylindric specimen using structured light
Quentin, Lorenz; Beermann, Rüdiger; Pösch, Andreas; Reithmeier, Eduard; Kästner, Markus
2017-06-01
We present a fringe projection system to measure glowing hot hybrid components in between production processes. For this a high power green light projector, based on TI DLP technology, is used to create the highest possible contrast between fringes on the red glowing specimen. It has a resolution of 1140 x 912 pixels with a maximum frame rate of 120 images per second for fast measurement. We use a green bandpass filter (525 nm) on the camera lens to block unwanted incoming radiation from the specimen caused by self-emission. Commercial measurement standards are not calibrated for temperatures other than 20° C, so they cannot be used to validate measurement data at the required temperatures of up to 1000°C since thermal expansion invalidates the geometry specification from the calibration data sheet. In our first development we use a uniformly heated pipe made of stainless steel as a dummy specimen to examine the measured geometry data. A pyrometer measures the temperature of the pipe so the expansion can be easily calculated using the thermal expansion coefficient. Different impact and triangulation angles are investigated to identify the effects of hot ambient air on the measurement. The impact of the induced refractive index gradient is examined to check the need for pre-processing steps in the measurement routine.
International Nuclear Information System (INIS)
Goodarzi, M.; Ramezanpour, R.
2014-01-01
Highlights: • Alternative cross sections for natural draft cooling tower were proposed. • Numerical solution was applied to study thermal and hydraulic performances. • Thermal and hydraulic performances were assessed by comparative parameters. • Cooling tower with elliptical cross section had better thermal performance under crosswind. • It could successfully used at the regions with invariant wind direction. - Abstract: Cooling efficiency of a natural draft dry cooling tower may significantly decrease under crosswind condition. Therefore, many researchers attempted to improve the cooling efficiency under this condition by using structural or mechanical facilities. In this article, alternative shell geometry with elliptical cross section is proposed for this type of cooling tower instead of usual shell geometry with circular cross section. Thermal performance and cooling efficiency of the two types of cooling towers are numerically investigated. Numerical simulations show that cooling tower with elliptical cross section improves the cooling efficiency compared to the usual type with circular cross section under high-speed wind moving normal to the longitudinal diameter of the elliptical cooling tower
International Nuclear Information System (INIS)
Hill, T. R.; Reed, W. H.
1980-01-01
1 - Description of problem or function: TIMEX solves the time- dependent, one-dimensional multigroup transport equation with delayed neutrons in plane, cylindrical, spherical, and two-angle plane geometries. Both regular and adjoint, inhomogeneous and homogeneous problems subject to vacuum, reflective, periodic, white, albedo or inhomogeneous boundary flux conditions are solved. General anisotropic scattering is allowed and anisotropic inhomogeneous sources are permitted. 2 - Method of solution: The discrete ordinates approximation for the angular variable is used with the diamond (central) difference approximation for the angular extrapolation in curved geometries. A linear discontinuous finite element representation for the angular flux in each spatial mesh cell is used. Negative fluxes are eliminated by a local set-to-zero and correct algorithm. The time variable is differenced by an explicit technique that is unconditionally stable so that arbitrarily large time-steps can be taken. Two acceleration methods, exponential extrapolation and re-balance, are utilized to improve the accuracy of the time differencing scheme. 3 - Restrictions on the complexity of the problem: Variable dimensioning is used so that any combination of problem parameters leading to a container array less than MAXCOR can be accommodated. In addition, the CDC version permits the use of extended core storage less than MAXECS
Energy Technology Data Exchange (ETDEWEB)
Lamare, J de; Mathelot, P; Cadhilac, M [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires
1960-07-01
In the present report, we explain an original method to perform exact calculations of neutron flux in either of two geometries: a slab surrounded by an infinite multiplying medium or a periodical, one dimensional array of two different media. (author) [French] La methode exposee dans ce rapport permet de calculer exactement la distribution du flux dans un milieu multiplicateur infini dont l'uniformite est perturbee par l'interposition d'une lame plane de nature differente, ou dont l'heterogeneite est de caractere periodique et unidimensionnel. (auteur)
International Nuclear Information System (INIS)
Zhang, Dingkang; Rahnema, Farzad; Ougouag, Abderrfi M.
2011-01-01
A response-based local transport method has been developed in 2-D (r, θ) geometry for coupling to any coarse-mesh (nodal) diffusion method/code. Monte Carlo method is first used to generate a (pre-computed) the response function library for each unique coarse mesh in the transport domain (e.g., the outer reflector region of the Pebble Bed Reactor). The scalar flux and net current at the diffusion/transport interface provided by the diffusion method are used as an incoming surface source to the transport domain. A deterministic iterative sweeping method together with the response function library is utilized to compute the local transport solution within all transport coarse meshes. After the partial angular currents crossing the coarse mesh surfaces are converged, albedo coefficients are computed as boundary conditions for the diffusion methods. The iteration on the albedo boundary condition (for the diffusion method via transport) and the incoming angular flux boundary condition (for the transport via diffusion) is continued until convergence is achieved. The method was tested for in a simplified 2-D (r, θ) pebble bed reactor problem consisting of an inner reflector, an annular fuel region and a controlled outer reflector. The comparisons have shown that the results of the response-function-based transport method agree very well with a direct MCNP whole core solution. The agreement in coarse mesh averaged flux was found to be excellent: relative difference of about 0.18% and a maximum difference of about 0.55%. Note that the MCNP uncertainty was less than 0.1%. (author)
International Nuclear Information System (INIS)
Lydia, Emilio J.; Barros, Ricardo C.
2011-01-01
In this paper we describe a response matrix method for one-speed slab-geometry discrete ordinates (SN) neutral particle transport problems that is completely free from spatial truncation errors. The unknowns in the method are the cell-edge angular fluxes of particles. The numerical results generated for these quantities are exactly those obtained from the analytic solution of the SN problem apart from finite arithmetic considerations. Our method is based on a spectral analysis that we perform in the SN equations with scattering inside a discretization cell of the spatial grid set up on the slab. As a result of this spectral analysis, we are able to obtain an expression for the local general solution of the SN equations. With this local general solution, we determine the response matrix and use the prescribed boundary conditions and continuity conditions to sweep across the discretization cells from left to right and from right to left across the slab, until a prescribed convergence criterion is satisfied. (author)
Safe-geometry pneumatic nuclear fuel powder blender
International Nuclear Information System (INIS)
Lyon, W.L.
1980-01-01
A safe geometry nuclear fuel powder is claimed blender of a pneumatic type having a plurality of narrow flat-walled blending chambers or ''slab tanks'' extending radially outward from a pneumatic spouting tube having an inlet and an outlet at bottom and top, respectively, open to each slab tank or blending chamber and contained within a cylindrical cone-bottomed shell filled with neutron-absorbing material between the blending chambers
Marcaillou, B.; Laurencin, M.; Graindorge, D.; Klingelhoefer, F.
2017-12-01
In subduction zones, the 3D geometry of the plate interface is thought to be a key parameter for the control of margin tectonic deformation, interplate coupling and seismogenic behavior. In the northern Caribbean subduction, precisely between the Virgin Islands and northern Lesser Antilles, these subjects remain controversial or unresolved. During the ANTITHESIS cruises (2013-2016), we recorded wide-angle seismic, multichannel reflection seismic and bathymetric data along this zone in order to constrain the nature and the geometry of the subducting and upper plate. This experiment results in the following conclusions: 1) The Anegada Passage is a 450-km long structure accross the forearc related to the extension due to the collision with the Bahamas platform. 2) More recently, the tectonic partitioning due to the plate convergence obliquity re-activated the Anegada Passage in the left-lateral strike-slip system. The partitioning also generated the left-lateral strike-slip Bunce Fault, separating the accretionary prism from the forearc. 3) Offshore of the Virgin Islands margin, the subducting plate shows normal faults parallel to the ancient spreading center that correspond to the primary fabric of the oceanic crust. In contrast, offshore of Barbuda Island, the oceanic crust fabric is unresolved (fracture zone?, exhumed mantle? ). 4) In the direction of the plate convergence vector, the slab deepening angle decreases northward. It results in a shallower slab beneath the Virgin Islands Platform compared to the St Martin-Barbuda forearc. In the past, the collision of the Bahamas platform likely changed the geodynamic settings of the northeastern corner of the Caribbean subduction zone and we present a revised geodynamic history of the region. Currently, various features are likely to control the 3D geometry of the slab: the margin convexity, the convergence obliquity, the heterogeneity of the primary fabric of the oceanic crust and the Bahamas docking. We suggest that
International Nuclear Information System (INIS)
Núñez, Jóse; Ramos, Eduardo; Lopez, Juan M
2012-01-01
We describe a hybrid method based on the combined use of the Fourier Galerkin and finite-volume techniques to solve the fluid dynamics equations in cylindrical geometries. A Fourier expansion is used in the angular direction, partially translating the problem to the Fourier space and then solving the resulting equations using a finite-volume technique. We also describe an algorithm required to solve the coupled mass and momentum conservation equations similar to a pressure-correction SIMPLE method that is adapted for the present formulation. Using the Fourier–Galerkin method for the azimuthal direction has two advantages. Firstly, it has a high-order approximation of the partial derivatives in the angular direction, and secondly, it naturally satisfies the azimuthal periodic boundary conditions. Also, using the finite-volume method in the r and z directions allows one to handle boundary conditions with discontinuities in those directions. It is important to remark that with this method, the resulting linear system of equations are band-diagonal, leading to fast and efficient solvers. The benefits of the mixed method are illustrated with example problems. (paper)
Directory of Open Access Journals (Sweden)
Juan Pablo Covarrubias V.
2012-12-01
condiciones de cargas mecánicas y térmicas en diferentes posiciones. El agrietamiento de las losas se determina calculando la fatiga del hormigón y los modelos utilizados por la guía de diseño AASHTO del año 2007 y mediante calibración en secciones de prueba a gran escala. La nueva metodología diseña losas de hormigón que en promedio son 7 cm más delgadas para vías de alto tráfico en relación con el diseño tradicional de pavimentos AASHTO (1993. El método de diseño también es capaz de diseñar de manera eficiente pavimentos de hormigón para vías de menor volumen de tráfico que no son cubiertos con los actuales métodos de diseño de pavimento dando una alternativa a soluciones en asfalto.A new technology has been developed to design concrete pavements, which reduces slabs' thickness and optimizes their sizes, because of trucks axles' geometry. The design is supported by a gravel base treated with concrete or asphalt. It assumes there is no adherence between the base (existing pavement and the concrete slab. The core principle of this design method consists of designing a slab size, so that no more than one wheel set stays on a given slab, thus minimizing the critical tensile stress on the surface. Test segments have been built on a large scale and they have been tested under accelerated loads, with concrete thickness of 8, 15 and 20 cm, all of them having a gravel base and non-adhered asphaltic layers. Tests demonstrated that a reduced-size slab, of low thickness, might bear a considerable amount of equivalent axles before cracking takes place. Concrete slabs on gravel bases with 20 cm thickness did not suffer from cracking, in spite of being tested under more than 50 millions of equivalent axles. Slabs of 15 cm thickness suffered from cracking when tested under an average of 12 millions equivalent axles, while slabs of 8 cm thickness endured 75,000 equivalent axles before the first cracking took place. Besides the executed tests demonstrated that fiber
International Nuclear Information System (INIS)
Hennart, J.P.; Valle, E. del.
1995-01-01
A generalized nodal finite element formalism is presented, which covers virtually all known finit difference approximation to the discrete ordinates equations in slab geometry. This paper (Part 1) presents the theory of the so called open-quotes continuous moment methodsclose quotes, which include such well-known methods as the open-quotes diamond differenceclose quotes and the open-quotes characteristicclose quotes schemes. In a second paper (hereafter referred to as Part II), the authors will present the theory of the open-quotes discontinuous moment methodsclose quotes, consisting in particular of the open-quotes linear discontinuousclose quotes scheme as well as of an entire new class of schemes. Corresponding numerical results are available for all these schemes and will be presented in a third paper (Part III). 12 refs
Sossinsky, A B
2012-01-01
The book is an innovative modern exposition of geometry, or rather, of geometries; it is the first textbook in which Felix Klein's Erlangen Program (the action of transformation groups) is systematically used as the basis for defining various geometries. The course of study presented is dedicated to the proposition that all geometries are created equal--although some, of course, remain more equal than others. The author concentrates on several of the more distinguished and beautiful ones, which include what he terms "toy geometries", the geometries of Platonic bodies, discrete geometries, and classical continuous geometries. The text is based on first-year semester course lectures delivered at the Independent University of Moscow in 2003 and 2006. It is by no means a formal algebraic or analytic treatment of geometric topics, but rather, a highly visual exposition containing upwards of 200 illustrations. The reader is expected to possess a familiarity with elementary Euclidean geometry, albeit those lacking t...
Indian Academy of Sciences (India)
. In the previous article we looked at the origins of synthetic and analytic geometry. More practical minded people, the builders and navigators, were studying two other aspects of geometry- trigonometry and integral calculus. These are actually ...
Gabrielsson, Henrik
1999-01-01
The thesis presents results from a project dealing with ductility in high performance concrete structures. The main objectives were to investigate the material and structural ductility/brittleness of prestressed structural elements of High Performance Concrete (HPC). The aim was to get a better understanding of the fracture process and to study sudden and brittle failures formed by shear stresses. The project was split into three parts: (I) Torsion of cylindrical pole elements, (II) Shear, to...
Prasolov, V V
2015-01-01
This book provides a systematic introduction to various geometries, including Euclidean, affine, projective, spherical, and hyperbolic geometries. Also included is a chapter on infinite-dimensional generalizations of Euclidean and affine geometries. A uniform approach to different geometries, based on Klein's Erlangen Program is suggested, and similarities of various phenomena in all geometries are traced. An important notion of duality of geometric objects is highlighted throughout the book. The authors also include a detailed presentation of the theory of conics and quadrics, including the theory of conics for non-Euclidean geometries. The book contains many beautiful geometric facts and has plenty of problems, most of them with solutions, which nicely supplement the main text. With more than 150 figures illustrating the arguments, the book can be recommended as a textbook for undergraduate and graduate-level courses in geometry.
International Nuclear Information System (INIS)
Becker, A.; Gorry, J.; Lame, J.
1984-07-01
Many ''sources'' of radioactive substances possess cylindrical geometry (waste drums for example) and gamma spectrometric detectors, as far as their active (selective) elements are concerned, are generally characterised by rotational symmetry about an axis. Such a situation may offer an analytical approach to the determination of the response of a cylindrical detector to a radiation produced homogeneously in a cylindrical emitter. Owing to the selective possibilities of spectrometry (in particular photoelectric effect) it is possible to reason purely in terms of transmission and absorption, which allows a formulation of the kind encountered in geometrical optics. In the present text we have developed the analytical expression beyond the limits from which most articles dealing with similar subjects have employed random sampling integration. Using a coaxial set-up in all cases, but with various relative dimensions of the right cylinder trunks (emitters and receivers), we have extracted fourfold definite integrals (with certain variable limits) giving the absolute and intrinsic efficiencies of which the ratios could be optimised by appropriate relative sizing of the right cylinder trunks (emission and detection) [fr
Energy Technology Data Exchange (ETDEWEB)
Curbelo, Jesus P.; Silva, Odair P. da; Barros, Ricardo C. [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Instituto Politecnico. Programa de Pos-graduacao em Modelagem Computacional; Garcia, Carlos R., E-mail: cgh@instec.cu [Departamento de Ingenieria Nuclear, Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), La Habana (Cuba)
2017-07-01
Presented here is the application of the adjoint technique for solving source-detector discrete ordinates (S{sub N}) transport problems by using a spectral nodal method. For slab-geometry adjoint S-N model, the adjoint spectral Green's function method (SGF{sup †}) is extended to multigroup problems considering arbitrary L'th-order of scattering anisotropy, and the possibility of non-zero prescribed boundary conditions for the forward S{sub N} transport problems. The SGF{sup †} method converges numerical solutions that are completely free from spatial truncation errors. In order to generate numerical solutions of the SGF{sup †} equations, we use the partial adjoint one-node block inversion (NBI) iterative scheme. Partial adjoint NBI scheme uses the most recent estimates for the node-edge adjoint angular Fluxes in the outgoing directions of a given discretization node, to solve the resulting adjoint SN problem in that node for all the adjoint angular fluxes in the incoming directions, which constitute the outgoing adjoint angular fluxes for the adjacent node in the sweeping directions. Numerical results are given to illustrate the present spectral nodal method features and some advantages of using the adjoint technique in source-detector problems. author)
International Nuclear Information System (INIS)
Hong, Ser Gi; Lee, Deokjung
2015-01-01
A highly accurate S 4 eigenfunction-based nodal method has been developed to solve multi-group discrete ordinate neutral particle transport problems with a linearly anisotropic scattering in slab geometry. The new method solves the even-parity form of discrete ordinates transport equation with an arbitrary S N order angular quadrature using two sub-cell balance equations and the S 4 eigenfunctions of within-group transport equation. The four eigenfunctions from S 4 approximation have been chosen as basis functions for the spatial expansion of the angular flux in each mesh. The constant and cubic polynomial approximations are adopted for the scattering source terms from other energy groups and fission source. A nodal method using the conventional polynomial expansion and the sub-cell balances was also developed to be used for demonstrating the high accuracy of the new methods. Using the new methods, a multi-group eigenvalue problem has been solved as well as fixed source problems. The numerical test results of one-group problem show that the new method has third-order accuracy as mesh size is finely refined and it has much higher accuracies for large meshes than the diamond differencing method and the nodal method using sub-cell balances and polynomial expansion of angular flux. For multi-group problems including eigenvalue problem, it was demonstrated that the new method using the cubic polynomial approximation of the sources could produce very accurate solutions even with large mesh sizes. (author)
International Nuclear Information System (INIS)
Curbelo, Jesus P.; Silva, Odair P. da; Barros, Ricardo C.
2017-01-01
Presented here is the application of the adjoint technique for solving source{detector discrete ordinates (S N ) transport problems by using a spectral nodal method. For slab-geometry adjoint S-N model, the adjoint spectral Green's function method (SGF † ) is extended to multigroup problems considering arbitrary L'th-order of scattering anisotropy, and the possibility of non{zero prescribed boundary conditions for the forward S N transport problems. The SGF † method converges numerical solutions that are completely free from spatial truncation errors. In order to generate numerical solutions of the SGF † equations, we use the partial adjoint one{node block inversion (NBI) iterative scheme. Partial adjoint NBI scheme uses the most recent estimates for the node-edge adjoint angular Fluxes in the outgoing directions of a given discretization node, to solve the resulting adjoint SN problem in that node for all the adjoint angular fluxes in the incoming directions, which constitute the outgoing adjoint angular fluxes for the adjacent node in the sweeping directions. Numerical results are given to illustrate the present spectral nodal method features and some advantages of using the adjoint technique in source-detector problems. author)
Energy Technology Data Exchange (ETDEWEB)
Curbelo, Jesus P.; Alves Filho, Hermes; Barros, Ricardo C., E-mail: jperez@iprj.uerj.br, E-mail: halves@iprj.uerj.br, E-mail: rcbarros@pq.cnpq.br [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Instituto Politecnico. Programa de Pos-Graduacao em Modelagem Computacional; Hernandez, Carlos R.G., E-mail: cgh@instec.cu [Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), La Habana (Cuba)
2015-07-01
The spectral Green's function (SGF) method is a numerical method that is free of spatial truncation errors for slab-geometry fixed-source discrete ordinates (S{sub N}) adjoint problems. The method is based on the standard spatially discretized adjoint S{sub N} balance equations and a nonstandard adjoint auxiliary equation expressing the node-average adjoint angular flux, in each discretization node, as a weighted combination of the node-edge outgoing adjoint fluxes. The auxiliary equation contains parameters which act as Green's functions for the cell-average adjoint angular flux. These parameters are determined by means of a spectral analysis which yields the local general solution of the S{sub N} equations within each node of the discretization grid. In this work a number of advances in the SGF adjoint method are presented: the method is extended to adjoint S{sub N} problems considering linearly anisotropic scattering and non-zero prescribed boundary conditions for the forward source-detector problem. Numerical results to typical model problems are considered to illustrate the efficiency and accuracy of the o offered method. (author)
Buschinelli, Pedro D. V.; Melo, João. Ricardo C.; Albertazzi, Armando; Santos, João. M. C.; Camerini, Claudio S.
2013-04-01
An axis-symmetrical optical laser triangulation system was developed by the authors to measure the inner geometry of long pipes used in the oil industry. It has a special optical configuration able to acquire shape information of the inner geometry of a section of a pipe from a single image frame. A collimated laser beam is pointed to the tip of a 45° conical mirror. The laser light is reflected in such a way that a radial light sheet is formed and intercepts the inner geometry and forms a bright laser line on a section of the inspected pipe. A camera acquires the image of the laser line through a wide angle lens. An odometer-based triggering system is used to shot the camera to acquire a set of equally spaced images at high speed while the device is moved along the pipe's axis. Image processing is done in real-time (between images acquisitions) thanks to the use of parallel computing technology. The measured geometry is analyzed to identify corrosion damages. The measured geometry and results are graphically presented using virtual reality techniques and devices as 3D glasses and head-mounted displays. The paper describes the measurement principles, calibration strategies, laboratory evaluation of the developed device, as well as, a practical example of a corroded pipe used in an industrial gas production plant.
Directory of Open Access Journals (Sweden)
Sven M. Ivansson
2009-01-01
Full Text Available Phononic crystals (PCs can be used as acoustic frequency selective insulators and filters. In a two-dimensional (2D PC, cylindrical scatterers with a common axis direction are located periodically in a host medium. In the present paper, the layer multiple-scattering (LMS computational method for wave propagation through 2D PC slabs is formulated and implemented for general 3D incident-wave directions and polarizations. Extensions are made to slabs with cylindrical scatterers of different types within each layer. As an application, the problem is considered to design such a slab with small sound transmittance within a given frequency band and solid angle region for the direction of the incident plane wave. The design problem, with variable parameters characterizing the scatterer geometry and material, is solved by differential evolution, a global optimization algorithm for efficiently navigating parameter landscapes. The efficacy of the procedure is illustrated by comparison to a direct Monte Carlo method.
International Nuclear Information System (INIS)
Salehi, A. A.; Vosoughi, N.; Shahriari, M.
2002-01-01
In reactor core neutronic calculations, we usually choose a control volume and investigate about the input, output, production and absorption inside it. Finally, we derive neutron transport equation. This equation is not easy to solve for simple and symmetrical geometry. The objective of this paper is to introduce a new direct method for neutronic calculations. This method is based on physics of problem and with meshing of the desired geometry, writing the balance equation for each mesh intervals and with notice to the conjunction between these mesh intervals, produce the final discrete equation series without production of neutron transport differential equation and mandatory passing form differential equation bridge. This method, which is named Direct Discrete Method, was applied in static state, for a cylindrical geometry in one group energy. The validity of the results from this new method are tested with MCNP-4B code with a one group energy library. One energy group direct discrete equation produces excellent results, which can be compared with the results of MCNP-4B
Pedoe, Dan
1988-01-01
""A lucid and masterly survey."" - Mathematics Gazette Professor Pedoe is widely known as a fine teacher and a fine geometer. His abilities in both areas are clearly evident in this self-contained, well-written, and lucid introduction to the scope and methods of elementary geometry. It covers the geometry usually included in undergraduate courses in mathematics, except for the theory of convex sets. Based on a course given by the author for several years at the University of Minnesota, the main purpose of the book is to increase geometrical, and therefore mathematical, understanding and to he
Han, Qing; Zhang, Chi; Xu, Bo; Chen, Jiangping
2013-07-01
The hydrodynamic flow behavior, effects of geometry and working conditions of a gas-liquid cylindrical cyclone separator with a new structure are investigated by computational fluid dynamic and experiment. Gas liquid cylindrical cyclone separator is widely used in oil industry, refrigeration system because of its simple structure, high separating efficiency, little maintenance and no moving parts nor internal devices. In this work, a gas liquid cylindrical cyclone separator with new structure used before evaporator in refrigeration system can remove the vapor from the mixture and make evaporator compact by improving its heat exchange efficiency with the lower inlet quality. It also decreases evaporator pressure drop and reduces compressor work. The two pipes are placed symmetrically which makes each of them can be treated as inlet. It means when the fluids flow reverse, the separator performance will not be influence. Four samples with different geometry parameters are tested by experiment with different inlet quality (0.18-0.33), inlet mass flow rate (65-100kg/h). Compared with the experimental data, CFD simulation results show a good agreement. Eulerian multiphase model and Reynolds Stress Turbulence model are applied in the CFD simulation and obtained the inner flow field such as phase path lines, tangential velocity profiles and pressure and volume of fraction distribution contours. The separator body diameter (24, 36, 48mm) and inlet diameter (3.84, 4.8, 5.76mm) decide the maximum tangential velocity which results in the centrifugal force. The tangential velocity profiles are simulated and compared among different models. The higher tangential velocity makes higher quality of gas outlet but high pressure drop at the same time. Decreasing the inlet diameter increases quality of gas outlet pipe and pressure drop. High gas outlet quality is cost at high pressure drop. Increasing of separator diameter makes gas outlet quality increase first and then decrease but
Pellenq, Roland J-M; Coasne, Benoit; Denoyel, Renaud O; Coussy, O
2009-02-03
A simple phenomenological model that describes capillary condensation and evaporation of pure fluids confined in cylindrical mesopores is presented. Following the work of Celestini (Celestini, F. Phys. Lett. A 1997, 228, 84), the free energy density of the system is derived using interfacial tensions and a corrective term that accounts for the interaction coupling between the vapor/adsorbed liquid and the adsorbed liquid/adsorbent interfaces. This corrective term is shown to be consistent with the Gibbs adsorption isotherm and assessed by standard adsorption tests. This model reveals that capillary condensation and evaporation are metastable and equilibrium processes, respectively, hence exhibiting the existence of a hysteresis loop inadsorption/desorption isotherm that is well-known in experiment. We extend the phenomenological model of Celestini to give a quantitative description of adsorption on the pore wall and hysteresis width evolution with temperature and confinement. Direct quantitative comparison is made with experimental data for confined argon. Used as a characterizing tool, this integrated model allows in a single fit of an experimental adsorption/desorption isotherm assessing essential characterization data such as the specific surface area, pore volume, and mean pore size.
International Nuclear Information System (INIS)
Brandan, M.E.
1979-01-01
Cellular survival experiments have shown that the biological damage induced by radiation depends on the density of energy deposition along the trajectory of the ionizing particle. The quantity L is defined to measure the density of energy transfer along a charged particle's trajectory. It is equal to sigma/l, where sigma is the energy transferred to a medium and l is the path length along which the transfer takes place. L is the stochastic quantity whose mean value is the unrestricted linear energy transfer, L/sub infinity/. Measurements of the distribution of L in a thin medium by secondary charged particles from fast neutron irradiation were undertaken. A counter operating under time coincidence between two coaxial cylindrical detectors was designed and built for this purpose. Secondary charged particles enter a gas proportional counter and deposit some energy sigma. Those particles traversing the chamber along a radial trajectory strike a CsI scintillator. A coincidence between both detectors' signals selects a known path length for these events, namely the radius of the cavity. Measurements of L distributions for l = 1 μm in tissue were obtained for 3 and 15 MeV neutron irradiation of a tissue-equivalent target wall and for 15 MeV neutron irradiation of a graphite wall. Photon events were corrected for by measurements with a Pb target wall and 15 MeV neutron irradiation as well as exposure to a pure photon field. The measured TE wall distributions with 15 MeV neutron bombardment show contributions from protons, α-particles, 9 Be and 12 C recoils. The last three comprise the L distribution for irradiation of the graphite wall. The proton component of the measured L distributions at 3 and 15 MeV was compared to calculated LET distributions
Energy Technology Data Exchange (ETDEWEB)
Amouyal, A; Tariel, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1966-07-01
Code name: January 1{sup st} SCEA 011S. 2) Computer: IBM 7094; Programme system: Fortran II, 2{sup nd} version. 3) Nature of the problem: resolution of cell problems with one space variable (planar, spherical and cylindrical geometries) and with one energy group, with isotropic sources in the double P{sub n} approximation (DP 1 and DP 3 approximation in planar and spherical geometries, DP 1 and DP 2 in cylindrical geometry). 4) Method used: the differential equations with limiting conditions are transformed into differential system with initial conditions which are integrated by a separate-step method. 5) Restrictions: number of physical media < 100, number of geometrical regions < 100, number of points < 1000. 6) Physical approximations: limiting conditions for reflection, black body or grey body (restrictions for spherical and cylindrical geometries). The diffusion can include an isotropy term in cylindrical geometry, 2 terms in the other geometries. Taking into account of macroscopic data. 7) Duration: calculation time for a network of 100 points: planar and spherical geometry: double P 1 1 second, D P 3 = 4 seconds; cylindrical geometry: double P 1 2 seconds, D P 2 = 4 seconds. To these times should be added the 3 seconds required for the output. 8) State of the programme under production. (authors) [French] 1) Nom du Code: Janvier 1 SCEA 011S. 2) Calculateur: IBM 7094; Systeme de programmation: Fortran II version-2. 3) Nature du probleme: resolution des problemes de cellule a une variable d'espace (geometries plane, spherique et cylindrique) et un groupe d'energie, avec sources isotropes, dans l'approxirnation double P{sub n} (Approximations DP 1 et DP 3 en geometrie plane et spherique, approximations DP 1 et DP 2 en geometrie cylindrique). Methode employee: les equations differentielles avec conditions aux limites sont transformees en systemes differentiels avec conditions initiales que l'on integre par une methode a pas separes. 5) Restrictions: nombre de
The dynamics of double slab subduction
Holt, A. F.; Royden, L. H.; Becker, T. W.
2017-04-01
We use numerical models to investigate the dynamics of two interacting slabs with parallel trenches. Cases considered are: a single slab reference, outward dipping slabs (out-dip), inward dipping slabs (in-dip) and slabs dipping in the same direction (same-dip). Where trenches converge over time (same-dip and out-dip systems), large positive dynamic pressures in the asthenosphere are generated beneath the middle plate and large trench-normal extensional forces are transmitted through the middle plate. This results in slabs that dip away from the middle plate at depth, independent of trench geometry. The single slab, the front slab in the same-dip case and both out-dip slabs undergo trench retreat and exhibit stable subduction. However, slabs within the other double subduction systems tend to completely overturn at the base of the upper mantle, and exhibit either trench advance (rear slab in same-dip), or near-stationary trenches (in-dip). For all slabs, the net slab-normal dynamic pressure at 330 km depth is nearly equal to the slab-normal force induced by slab buoyancy. For double subduction, the net outward force on the slabs due to dynamic pressure from the asthenosphere is effectively counterbalanced by the net extensional force transmitted through the middle plate. Thus, dynamic pressure at depth, interplate coupling and lithospheric stresses are closely linked and their effects cannot be isolated. Our results provide insights into both the temporal evolution of double slab systems on Earth and, more generally, how the various components of subduction systems, from mantle flow/pressure to interplate coupling, are dynamically linked.
Photon transport in thin disordered slabs
Indian Academy of Sciences (India)
We examine using Monte Carlo simulations, photon transport in optically `thin' slabs whose thickness is only a few times the transport mean free path *, with particles of different scattering anisotropies. The conﬁned geometry causes an auto-selection of only photons with looping paths to remain within the slab.
International Nuclear Information System (INIS)
McCoy, D.R.
1981-01-01
S/sub N/ computational benchmark solutions are generated for a onegroup and multigroup fuel-void slab lattice cell which is a rough model of a gas-cooled fast reactor (GCFR) lattice cell. The reactivity induced by the extrusion of the fuel material into the voided region is determined for a series of partially extruded lattice cell configurations. A special modified Gauss S/sub N/ ordinate array design is developed in order to obtain eigenvalues with errors less than 0.03% in all of the configurations that are considered. The modified Gauss S/sub N/ ordinate array design has a substantially improved eigenvalue angular convergence behavior when compared to existing S/sub N/ ordinate array designs used in neutron streaming applications. The angular refinement computations are performed in some cases by using a perturbation theory method which enables one to obtain high order S/sub N/ eigenvalue estimates for greatly reduced computational costs
Flowing Air-Water Cooled Slab Nd: Glass Laser
Lu, Baida; Cai, Bangwei; Liao, Y.; Xu, Shifa; Xin, Z.
1989-03-01
A zig-zag optical path slab geometry Nd: glass laser cooled through flowing air-water is developed by us. Theoretical studies on temperature distribution of slab and rod configurations in the unsteady state clarify the advantages of the slab geometry laser. The slab design and processing are also reported. In our experiments main laser output characteristics, e. g. laser efficiency, polarization, far-field divergence angle as well as resonator misalignment are investigated. The slab phosphate glass laser in combination with a crossed Porro-prism resonator demonstrates a good laser performance.
Energy Technology Data Exchange (ETDEWEB)
Guida, Mateus Rodrigues; Alves Filho, Hermes; Barros, Ricardo C., E-mail: mguida@iprj.uerj.br, E-mail: halves@iprj.uerj.br, E-mail: rcbarros@pq.cnpq.br [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Instituto Politecnico. Programa de Pos-Graduacao em Modelagem Computacional
2015-07-01
The scattering source iterative (SI) scheme is applied traditionally to converge fine-mesh numerical solutions to fixed-source discrete ordinates (S{sub N}) neutron transport problems with linearly anisotropic scattering. The SI scheme is very simple to implement under a computational viewpoint. However, the SI scheme may show very slow convergence rate, mainly for diffusive media (low absorption) with several mean free paths in extent. In this work we describe two acceleration techniques based on improved initial guesses for the SI scheme, wherein we initialize the scattering source distribution within the slab using the P{sub 1} and P{sub 3} approximations. In order to estimate these initial guesses, we use the coarse-mesh solution of the PN equations with special boundary conditions to account for the classical S{sub N} prescribed boundary conditions, including vacuum boundary conditions. To apply this coarse-mesh P{sub N} solution for the accelerated scheme, we first perform within-node spatial reconstruction, and then we determine the fine-mesh average scalar flux and total current for initializing the linearly anisotropic scattering source terms for the SI scheme. We consider a number of numerical experiments to illustrate the efficiency of the offered P{sub N} synthetic acceleration (P{sub N}SA) technique based on initial guess. (author)
International Nuclear Information System (INIS)
Santos, Frederico P.; Xavier, Vinicius S.; Alves Filho, Hermes; Barros, Ricardo C.
2011-01-01
The scattering source iterative (SI) scheme is traditionally applied to converge fine-mesh numerical solutions to fixed-source discrete ordinates (S N ) neutron transport problems. The SI scheme is very simple to implement under a computational viewpoint. However, the SI scheme may show very slow convergence rate, mainly for diffusive media (low absorption) with several mean free paths in extent. In this work we describe an acceleration technique based on an improved initial guess for the scattering source distribution within the slab. In other words, we use as initial guess for the fine-mesh scattering source, the coarse-mesh solution of the neutron diffusion equation with special boundary conditions to account for the classical S N prescribed boundary conditions, including vacuum boundary conditions. Therefore, we first implement a spectral nodal method that generates coarse-mesh diffusion solution that is completely free from spatial truncation errors, then we reconstruct this coarse-mesh solution within each spatial cell of the discretization grid, to further yield the initial guess for the fine-mesh scattering source in the first S N transport sweep (μm > 0 and μm < 0, m = 1:N) across the spatial grid. We consider a number of numerical experiments to illustrate the efficiency of the offered diffusion synthetic acceleration (DSA) technique. (author)
International Nuclear Information System (INIS)
Santos, Frederico P.; Alves Filho, Hermes; Barros, Ricardo C.; Xavier, Vinicius S.
2011-01-01
The scattering source iterative (SI) scheme is traditionally applied to converge fine-mesh numerical solutions to fixed-source discrete ordinates (S N ) neutron transport problems. The SI scheme is very simple to implement under a computational viewpoint. However, the SI scheme may show very slow convergence rate, mainly for diffusive media (low absorption) with several mean free paths in extent. In this work we describe an acceleration technique based on an improved initial guess for the scattering source distribution within the slab. In other words, we use as initial guess for the fine-mesh scattering source, the coarse-mesh solution of the neutron diffusion equation with special boundary conditions to account for the classical S N prescribed boundary conditions, including vacuum boundary conditions. Therefore, we first implement a spectral nodal method that generates coarse-mesh diffusion solution that is completely free from spatial truncation errors, then we reconstruct this coarse-mesh solution within each spatial cell of the discretization grid, to further yield the initial guess for the fine-mesh scattering source in the first S N transport sweep (μm > 0 and μm < 0, m = 1:N) across the spatial grid. We consider a number of numerical experiments to illustrate the efficiency of the offered diffusion synthetic acceleration (DSA) technique. (author)
Energy Technology Data Exchange (ETDEWEB)
Slipicevic, K [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Yugoslavia)
1968-07-01
Following a review of the existing theories od resonance absorption this thesis includes a new approach for calculating the effective resonance integral of absorbed neutrons, new approximate formula for the penetration factor, an analysis of the effective resonance integral and the correction of the resonance integral taking into account the interference of potential and resonance dissipation. A separate chapter is devoted to calculation of the effective resonance integral for the regular reactor lattice with cylindrical fuel elements.
Li, Bo; Guo, Ming-Zhe; Yu, Hui; Chen, Shao-Xia
2018-03-01
Impulsively generated sausage wave trains in coronal structures are important for interpreting a substantial number of observations of quasi-periodic signals with quasi-periods of order seconds. We have previously shown that the Morlet spectra of these wave trains in coronal tubes depend crucially on the dispersive properties of trapped sausage waves, the existence of cutoff axial wavenumbers, and the monotonicity of the dependence of the axial group speed on the axial wavenumber in particular. This study examines the difference a slab geometry may introduce, for which purpose we conduct a comprehensive eigenmode analysis, both analytically and numerically, on trapped sausage modes in coronal slabs with a considerable number of density profiles. For the profile descriptions examined, coronal slabs can trap sausage waves with longer axial wavelengths, and the group speed approaches the internal Alfvén speed more rapidly at large wavenumbers in the cylindrical case. However, common to both geometries, cutoff wavenumbers exist only when the density profile falls sufficiently rapidly at distances far from coronal structures. Likewise, the monotonicity of the group speed curves depends critically on the profile steepness right at the structure axis. Furthermore, the Morlet spectra of the wave trains are shaped by the group speed curves for coronal slabs and tubes alike. Consequently, we conclude that these spectra have the potential for inferring the subresolution density structuring inside coronal structures, although their detection requires an instrumental cadence of better than ∼1 s.
Energy Technology Data Exchange (ETDEWEB)
Bal, G. [Departement MMN, Service IMA, Direction des Etudes et Recherches, Electricite de France (EDF), 92 - Clamart (France)
1995-10-01
Neutron transport in nuclear reactors is quite well modelled by the linear Boltzmann transport equation. Its solution is relatively easy, but unfortunately too expensive to achieve whole core computations. Thus, we have to simplify it, for example by homogenizing some physical characteristics. However, the solution may then be inaccurate. Moreover, in strongly homogeneous areas, the error may be too big. Then we would like to deal with such an inconvenient by solving the equation accurately on this area, but more coarsely away from it, so that the computation is not too expensive. This problem is the subject of a thesis. We present here some results obtained for slab geometry. The couplings between the fine and coarse discretization regions could be conceived in a number of approaches. Here, we only deal with the coupling at crossing the interface between two sub-domains. In the first section, we present the coupling of discrete ordinate methods for solving the homogeneous, isotropic and mono-kinetic equation. Coupling operators are defined and shown to be optimal. The second and the third sections are devoted to an extension of the previous results when the equation is non-homogeneous, anisotropic and multigroup (under some restrictive assumptions). Some numerical results are given in the case of isotropic and mono-kinetic equations. (author) 15 refs.
International Nuclear Information System (INIS)
Pal, T.K.; Bajpai, R.K.; Datta, D.
2016-01-01
Differential Quadrature Method (DQM) based computational scheme is developed to solve diffusion equation in cylindrical coordinate. In this scheme, time derivative is approximated using forward difference and the spatial derivatives using polynomial based DQM. This developed scheme is applied to simulate test problem on radionuclide leaching from radioactive waste form. Leach rate is calculated after simulating the leaching process. DQM based results are compared with the analytical solutions and good agreements between the two results are established. The developed tool is used as a numerical tool for computationally intensive calculations, such as regression analysis and correlation analysis etc. Multivariate regression analysis is carried out to establish a linear relationship between leach rate and model parameters e.g., diffusion coefficient, porosity and linear sorption coefficient. Study of correlation analysis carried out in this study shows that diffusion coefficient is positively more correlated with leach rate compared to porosity whereas, K_d is negatively correlated with leach rate. (author)
Analytical model for shear strength of end slabs of prestressed concrete nuclear reactor vessels
International Nuclear Information System (INIS)
Abdulrahman, H.O.; Sozen, M.A.; Schnobrich, W.C.
1979-04-01
The results are presented of an investigation of the behavior and strength of flat end slabs of cylindrical prestressed concrete nuclear reactor vessels. The investigation included tests of ten small-scale pressure vessels and development of a nonlinear finite-element model to simulate the deformation response and strength of the end slabs. Because earlier experimental studies had shown that the flexural strength of the end slab could be calculated using intelligible procedures, the emphasis of this investigation was on shear strength
Slab replacement maturity guidelines.
2014-04-01
This study investigated the use of maturity method to determine early age strength of concrete in slab : replacement application. Specific objectives were (1) to evaluate effects of various factors on the compressive : maturity-strength relationship ...
Integral-equation formulation for drift eigenmodes in cylindrically symmetric systems
International Nuclear Information System (INIS)
Linsker, R.
1980-12-01
A method for solving the integral eigenmode equation for drift waves in cylindrical (or slab) geometry is presented. A leading-order kinematic effect that has been noted in the past, but incorrectly ignored in recent integral-equation calculations, is incorporated. The present method also allows electrons to be treated with a physical mass ratio (unlike earlier work that is restricted to artificially small m/sub i//m/sub e/ owing to resolution limitations). Results for the universal mode and for the ion-temperature-gradient driven mode are presented. The kinematic effect qualitatively changes the spectrum of the ion mode, and a new second region of instability for k/sub perpendicular to/rho/sub i/greater than or equal to 1 is found
The Raetrad model of radon generation and transport from soils into slab-on-grade houses
International Nuclear Information System (INIS)
Nielson, K.K.; Rogers, V.C.; Rogers, V.; Holt, R.B.
1994-01-01
Remediation planning and 222 Rn-related construction zoning require knowledge of how close and strong 226 Ra sources can be in different foundation soils under different groundwater conditions without excessively elevating indoor 222 Rn levels. A two-dimensional numerical-analytical model was developed to simulate (a) 222 Rn emanation, decay, and movement by diffusion and advection in soils around houses and in their understructures; and (b) 222 Rn accumulation in a single-zone house. The model represents foundation soils and a house in elliptical-cylindrical geometry. 222 Rn may diffuse through its floor slab or may enter via idealized cracks and openings. The model was validated with analytical calculations of two-dimensional air pressure fields and with one-dimensional calculations of 222 Rn generation with diffusion and diffusion combined with advection. Agreement generally was within 222 Rn measurements in two test-cell structures under passive and depressurized conditions averaged within 11% of measured values, well within measurement uncertainty. The corresponding average bias was only 3%. Larger variations were observed when applying the model to 50 houses. In this application, a negative bias of nearly 50% was observed due to data gaps and to poorly-characterized floor slabs and crack distributions. 41 refs., 11 fig., 3 tabs
Radon progeny distribution in cylindrical diffusion chambers
International Nuclear Information System (INIS)
Pressyanov, Dobromir S.
2008-01-01
An algorithm to model the diffusion of radioactive decay chain atoms is presented. Exact mathematical solutions in cylindrical geometry are given. They are used to obtain expressions for the concentrations of 222 Rn progeny atoms in the volume and deposited on the wall surface in cylindrical diffusion chambers. The dependence of volume fractions of 222 Rn progeny and chamber sensitivity on the coefficient of diffusion of 222 Rn progeny atoms in air is modeled.
Cylindrical dust acoustic waves with transverse perturbation
International Nuclear Information System (INIS)
Xue Jukui
2003-01-01
The nonlinear dust acoustic waves in dusty plasmas with the combined effects of bounded cylindrical geometry and the transverse perturbation are studied. Using the perturbation method, a cylindrical Kadomtsev-Petviashvili (CKP) equation that describes the dust acoustic waves is deduced for the first time. A particular solution of this CKP equation is also obtained. It is shown that the dust acoustic solitary waves can exist in the CKP equation
Acoustic characteristics of sand sediment with circular cylindrical pores
International Nuclear Information System (INIS)
Roh, Heui-Seol; Lee, Kang-Il; Yoon, Suk-Wang
2004-01-01
The acoustic pressure transmission coefficient and the phase velocity are experimentally measured as functions of the frequency and the porosity in sand sediment slabs with circular cylindrical pores filled with water and air. They are also theoretically estimated with the modified Biot-Attenborough (MBA) model, which uses a separate treatment of the viscous and the thermal effects in a non-rigid porous medium with water- and air-filled cylindrical pores. In this study, the fast (first kind) wave and the slow (second kind) wave are not separated in the transmitted signals through a sediment slab without the circular cylindrical pores, but they are separated in the transmitted signals through a sediment slab with pores. Both the phase velocities and the transmission coefficients of the fast wave and the slow wave in the sediment slabs with water- and air-filled cylindrical pores are sensitive to the air and the water porosities. It is proposed that the fast and the slow waves have opposite behaviors for several acoustic characteristics. The generalized tortuosity factor and the dynamic shape factor are introduced from the acoustic characteristics of the fast wave. The experimental results show reasonable agreement with the theoretical results estimated with the MBA model. These results suggest the possibility of predicting the acoustic characteristics of a sediment as functions of arbitrary water and air porosities. This study may also be applicable to understanding acoustic wave propagations in a bubbly liquid sediment for underwater applications and in cancellous bone for the diagnosis of osteoporosis.
DEFF Research Database (Denmark)
Thoft-Christensen, Palle
1989-01-01
In the paper it is shown how upper and lower bounds for the reliability of plastic slabs can be determined. For the fundamental case it is shown that optimal bounds of a deterministic and a stochastic analysis are obtained on the basis of the same failure mechanisms and the same stress fields....
Exact solution of the neutron transport equation in spherical geometry
Energy Technology Data Exchange (ETDEWEB)
Anli, Fikret; Akkurt, Abdullah; Yildirim, Hueseyin; Ates, Kemal [Kahramanmaras Suetcue Imam Univ. (Turkey). Faculty of Sciences and Letters
2017-03-15
Solution of the neutron transport equation in one dimensional slab geometry construct a basis for the solution of neutron transport equation in a curvilinear geometry. Therefore, in this work, we attempt to derive an exact analytical benchmark solution for both neutron transport equations in slab and spherical medium by using P{sub N} approximation which is widely used in neutron transport theory.
Energy Technology Data Exchange (ETDEWEB)
Leal, Andre Luiz do Carmo
2008-07-01
In this work we evaluate polynomial approximations to obtain the transfer functions that appear in SGF auxiliary equations (Green's Functions) for monoenergetic linearly anisotropic scattering SN equations in one-dimensional Cartesian geometry. For this task we use Lagrange Polynomials in order to compare the numerical results with the ones generated by the standard SGF method applied to SN problems in heterogeneous domains. This work is a preliminary investigation of a new proposal for handling the transverse leakage terms that appear in the transverse-integrated one-dimensional SN equations when we use the SGF - exponential nodal method (SGF-ExpN) in multidimensional rectangular geometry. (author)
Seismic Evidence for Possible Slab Melting from Strong Scattering Waves
Directory of Open Access Journals (Sweden)
Cheng-Horng Lin
2011-01-01
Full Text Available Slab melting in young and hot subduction zones has been studied using geochemical observations and thermal modelling, but there are few data from seismic studies to confirm slab melting. Also the detailed geometry in the deep part of the melting slab is often ambiguous in that the intraslab earthquakes within the Wadati-Benioff zone are only limited to shallower depths. To improve our understanding of both the seismic features and geometry found in a young and hot subducted slab, I analyzed anomalous moonquake-like seismograms that were generated by an intermediate-depth earthquake recorded in central Japan. For this study, possible reflected (or scattered sources were examined using detailed analyses of particle motions and a grid search for travel-time differences between the direct and later P-waves. The results show that using strong seismic scattering, slab melting is likely occurring in the deeper, flexing part of the subducted Philippine Sea plate. Because the subducted Philippine Sea plate in central Japan is young and therefore hot, partial melting might have taken place to produce abundant melting spots in the subducted slab. Melting spots, identified as ¡§bright spots,¡¨ could efficiently reflect or scatter seismic energy and generate many later phases with large amplitudes.
Post-Tensioned Concrete Long-Span Slabs in Projects of Modern Building Construction
Szydlowski, Rafal; Labuzek, Barbara
2017-10-01
Nowadays, design of modern an architectural building structures requires the use of slender and free from numerous supports slabs. The most suitable solution for above requirements are the post-tensioned slabs with unbounded tendons. Slabs prestressed by unbounded tendons are successfully used worldwide for several decades. During that time many recommendations dealing with the forming of geometry and prestressing, dimensioning and erection technology were issued. During the recent years prestressed slabs characterized by span and slenderness substantially exceeding recommended limitations were designed and erected with success in Poland. During the slabs erection and in two years of their using, the deflection of three oversized slabs were monitoring. In spite of designed the slabs significantly larger and slenderer than the recommended maximum value of span and span to depth ratio, the deflection of the slabs is definitely far from the limit value. The paper shows the geometry, characteristic and deflection of erected slabs and conclusion. Description of a very large span slab (21.3m), that was designed regarded to the information obtained from the previous realisation, is presented in this paper.
International Nuclear Information System (INIS)
Kokhanovsky, A.A.
2002-01-01
This paper is devoted to an alternative derivation of the asymptotic equations for the reflection and transmission functions of turbid slabs. The derivation is based on the reciprocity principle and the law of conservation of energy. Thus it is very general. This allows us to apply the obtained equations even in cases where the foundations of the radiative transfer theory are in question (e.g. for highly concentrated suspensions and pastes). (author)
International Nuclear Information System (INIS)
Satapathy, A.K.; Singh, K.C.
1996-01-01
The process of re-establishment of wetting of hot surface is of practical importance in chemical, metallurgical and nuclear industries. Rewetting is considered in emergency core cooling in nuclear reactors in the event of postulated loss of coolant accident (LOCA). This paper deals with numerical solution of the two-dimensional quasi-static conduction controlled rewetting of an infinite parallel sided composite slab assuming perfect contact is maintained at the interface. On the wetted side upstream of the quench front, a constant heat transfer coefficient is assumed. The downstream of quench front and unwetted side of slab are supposed to be adiabatic. The solution gives the quench front temperature as a function of various model parameters such as Peclet number, wet side Blot number, dimensionless thickness of slab and cladding to fuel ratio of thermal conductivities. The results show that for large values of rewetting velocities, the dimensionless rewetting temperature is unaffected by fuel properties for all values of Blot numbers. (author). 7 refs., 2 tabs., 1 fig
Linear simulations of the cylindrical Richtmyer-Meshkov instability in magnetohydrodynamics
Bakhsh, Abeer
2016-03-09
Numerical simulations and analysis indicate that the Richtmyer-Meshkov instability(RMI) is suppressed in ideal magnetohydrodynamics(MHD) in Cartesian slab geometry. Motivated by the presence of hydrodynamic instabilities in inertial confinement fusion and suppression by means of a magnetic field, we investigate the RMI via linear MHD simulations in cylindrical geometry. The physical setup is that of a Chisnell-type converging shock interacting with a density interface with either axial or azimuthal (2D) perturbations. The linear stability is examined in the context of an initial value problem (with a time-varying base state) wherein the linearized ideal MHD equations are solved with an upwind numerical method. Linear simulations in the absence of a magnetic field indicate that RMI growth rate during the early time period is similar to that observed in Cartesian geometry. However, this RMI phase is short-lived and followed by a Rayleigh-Taylor instability phase with an accompanied exponential increase in the perturbation amplitude. We examine several strengths of the magnetic field (characterized by β=2p/B^2_r) and observe a significant suppression of the instability for β ≤ 4. The suppression of the instability is attributed to the transport of vorticity away from the interface by Alfvén fronts.
Spinning geometry = Twisted geometry
International Nuclear Information System (INIS)
Freidel, Laurent; Ziprick, Jonathan
2014-01-01
It is well known that the SU(2)-gauge invariant phase space of loop gravity can be represented in terms of twisted geometries. These are piecewise-linear-flat geometries obtained by gluing together polyhedra, but the resulting geometries are not continuous across the faces. Here we show that this phase space can also be represented by continuous, piecewise-flat three-geometries called spinning geometries. These are composed of metric-flat three-cells glued together consistently. The geometry of each cell and the manner in which they are glued is compatible with the choice of fluxes and holonomies. We first remark that the fluxes provide each edge with an angular momentum. By studying the piecewise-flat geometries which minimize edge lengths, we show that these angular momenta can be literally interpreted as the spin of the edges: the geometries of all edges are necessarily helices. We also show that the compatibility of the gluing maps with the holonomy data results in the same conclusion. This shows that a spinning geometry represents a way to glue together the three-cells of a twisted geometry to form a continuous geometry which represents a point in the loop gravity phase space. (paper)
An investigation on cylindrical imploding turbulent mixing
International Nuclear Information System (INIS)
Liao Haidong; Yang Libin; Zhang Xilin; Ouyang Kai; Li Jun
2001-01-01
The interfacial instability experiments in cylindrically convergent geometry are performed by imploding jelly liner with high pressure gases; and instability growth were observed with high-speed framing camera. The relevant 2D numerical simulation programs were developed and their results are in good agreement with those of experiments
Tearing instability in cylindrical plasma configuration
International Nuclear Information System (INIS)
Zelenyj, L.M.
1979-01-01
The effect of the neutral-layer cylindrical geometry on the development of the tearing instability has been investigated in detail. The increments of the instability for all the regimes have been found. The influence of cylindrical effects becomes manifesting itself at small, as compared to the layer characteristic thickness, distances from the axis, and, finally, the electron regime of the instability development transforms into an ion one. The results obtained are of interest for studying the plasma stability in the devices of the ''Astron'' type and in magnetospheres of cosmic objects
Geometrical optics of dense aerosols: forming dense plasma slabs.
Hay, Michael J; Valeo, Ernest J; Fisch, Nathaniel J
2013-11-01
Assembling a freestanding, sharp-edged slab of homogeneous material that is much denser than gas, but much more rarefied than a solid, is an outstanding technological challenge. The solution may lie in focusing a dense aerosol to assume this geometry. However, whereas the geometrical optics of dilute aerosols is a well-developed field, the dense aerosol limit is mostly unexplored. Yet controlling the geometrical optics of dense aerosols is necessary in preparing such a material slab. Focusing dense aerosols is shown here to be possible, but the finite particle density reduces the effective Stokes number of the flow, a critical result for controlled focusing.
Long-life slab replacement concrete.
2015-03-01
This research was initiated following reports of high incidence of cracking on FDOT concrete pavement replacement : slab projects. Field slabs were instrumented for data acquisition from high-early-strength concrete pavement : replacement slabs place...
Topological Susceptibility from Slabs
Bietenholz, Wolfgang; Gerber, Urs
2015-01-01
In quantum field theories with topological sectors, a non-perturbative quantity of interest is the topological susceptibility chi_t. In principle it seems straightforward to measure chi_t by means of Monte Carlo simulations. However, for local update algorithms and fine lattice spacings, this tends to be difficult, since the Monte Carlo history rarely changes the topological sector. Here we test a method to measure chi_t even if data from only one sector are available. It is based on the topological charges in sub-volumes, which we denote as slabs. Assuming a Gaussian distribution of these charges, this method enables the evaluation of chi_t, as we demonstrate with numerical results for non-linear sigma-models.
Topological susceptibility from slabs
Energy Technology Data Exchange (ETDEWEB)
Bietenholz, Wolfgang [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A.P. 70-543, Distrito Federal, C.P. 04510 (Mexico); Forcrand, Philippe de [Institute for Theoretical Physics, ETH Zürich,CH-8093 Zürich (Switzerland); CERN, Physics Department, TH Unit, CH-1211 Geneva 23 (Switzerland); Gerber, Urs [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A.P. 70-543, Distrito Federal, C.P. 04510 (Mexico); Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo,Edificio C-3, Apdo. Postal 2-82, Morelia, Michoacán, C.P. 58040 (Mexico)
2015-12-14
In quantum field theories with topological sectors, a non-perturbative quantity of interest is the topological susceptibility χ{sub t}. In principle it seems straightforward to measure χ{sub t} by means of Monte Carlo simulations. However, for local update algorithms and fine lattice spacings, this tends to be difficult, since the Monte Carlo history rarely changes the topological sector. Here we test a method to measure χ{sub t} even if data from only one sector are available. It is based on the topological charges in sub-volumes, which we denote as slabs. Assuming a Gaussian distribution of these charges, this method enables the evaluation of χ{sub t}, as we demonstrate with numerical results for non-linear σ-models.
Optimal Material Layout - Applied on Reinforced Concrete Slabs
DEFF Research Database (Denmark)
Dollerup, Niels; Jepsen, Michael S.; Damkilde, Lars
2015-01-01
This paper introduces a general, finite-element-based optimisation tool for improving the material layout of concrete structures. The application presented is general and exemplified by material optimisation of reinforced concrete slabs. By utilising the optimisation tool, it is possible to deter......This paper introduces a general, finite-element-based optimisation tool for improving the material layout of concrete structures. The application presented is general and exemplified by material optimisation of reinforced concrete slabs. By utilising the optimisation tool, it is possible...... to determine the optimal material layout of a slab in the ultimate load state, based on simple inputs such as outer geometry, boundary conditions, multiple load cases and design domains. The material layout of the optimal design can either be fully orthotropic or isotropic, or a combination with a predefined...
Stein, H. J.; Hannah, J. L.
2017-12-01
The application of Re-Os isotope geochemistry to dating single oils is a nascent field [1,2]. Challenges include dissection of oils into asphaltene-maltene (ASPH-MALT) components in a way that preserves meaningful chronologic and source information. Significantly, oil-water mixing rapidly transfers Os to the oil, while Re exchange is sluggish [3]. The Os initial ratio of the oil is shifted in the direction of Os carried in the aqueous fluid, whereas the Re-Os isotopic age is preserved. We show that this phenomenon is operative in natural systems. Further, we show that deserpentinization of old oceanic slabs [4], may be linked to expulsion of Os-enriched waters into overlying sedimentary sections - a process that may be of fundamental importance for oil generation. This conclusion does not diminish the role of traditional organic-rich shales as source rocks for the hydrocarbon, but shows that external fluids are essential to petroleum generation. Moreover, the external fluids may be an important driver for expulsion and migration of oils. We have taken apart several petroleum systems from source rock, to residual oil, to tar mat development, to in situ live oil, through to produced oil. In many cases, a fluid with low 187Os/188Os - unlike that of normal basinal brines - provides a critical component to the oil-water mixture. Funding - CHRONOS project supported by Norwegian petroleum industry (Eni-Norge, Lundin, Aker BP) Acknowledgement - Christine Fichler [4], who first queried us on old slabs and oil, and stimulated ideas. [1] Georgiev, S.V., Stein, H.J., Hannah, J.L., Galimberti, R., Nali, M., Yang, G., and Zimmerman, A. (2016) Re-Os dating of maltenes and asphaltenes within single samples of crude oil: Geochim. Cosmochim. Acta 179: 53-75. [doi.org/10.1016/j.gca.2016.01.016] [2] DiMarzio, J., Georgiev, S.V., Stein, H.J., and Hannah, J.L. (in press) Residency of rhenium and osmium in a heavy crude oil: Geochim. Cosmochim. Acta. [3] Hurtig, N.C., Georgiev, S
Leung, Ka-Ngo [Hercules, CA
2008-04-22
A cylindrical neutron generator is formed with a coaxial RF-driven plasma ion source and target. A deuterium (or deuterium and tritium) plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical neutron generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which contain many slots. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired. The plasma generator may be in the center and the neutron target on the outside, or the plasma generator may be on the outside and the target on the inside. In a nested configuration, several concentric targets and plasma generating regions are nested to increase the neutron flux.
Investigation on the performance of bridge approach slab
Directory of Open Access Journals (Sweden)
Abdelrahman Amr
2018-01-01
Full Text Available In Egypt, where highway bridges are to be constructed on soft cohesive soils, the bridge abutments are usually founded on rigid piles, whereas the earth embankments for the bridge approaches are directly founded on the natural soft ground. Consequently, excessive differential settlement frequently occurs between the bridge deck and the bridge approaches resulting in a “bump” at both ends of the bridge deck. Such a bump not only creates a rough and uncomfortable ride but also represents a hazardous condition to traffic. One effective technique to cope with the bump problem is to use a reinforced concrete approach slab to provide a smooth grade transition between the bridge deck and the approach pavement. Investigating the geotechnical and structural performance of approach slabs and revealing the fundamental affecting factors have become mandatory. In this paper, a 2-D finite element model is employed to investigate the performance of approach slabs. Moreover, an extensive parametric study is carried out to appraise the relatively optimum geometries of approach slab, i.e. slab length, thickness, embedded depth and slope, that can yield permissible bumps. Different geo-mechanical conditions of the cohesive foundation soil and the fill material of the bridge embankment are examined.
Sub-wavelength grating mode transformers in silicon slab waveguides.
Bock, Przemek J; Cheben, Pavel; Schmid, Jens H; Delâge, André; Xu, Dan-Xia; Janz, Siegfried; Hall, Trevor J
2009-10-12
We report on several new types of sub-wavelength grating (SWG) gradient index structures for efficient mode coupling in high index contrast slab waveguides. Using a SWG, an adiabatic transition is achieved at the interface between silicon-on-insulator waveguides of different geometries. The SWG transition region minimizes both fundamental mode mismatch loss and coupling to higher order modes. By creating the gradient effective index region in the direction of propagation, we demonstrate that efficient vertical mode transformation can be achieved between slab waveguides of different core thickness. The structures which we propose can be fabricated by a single etch step. Using 3D finite-difference time-domain simulations we study the loss, polarization dependence and the higher order mode excitation for two types (triangular and triangular-transverse) of SWG transition regions between silicon-on-insulator slab waveguides of different core thicknesses. We demonstrate two solutions to reduce the polarization dependent loss of these structures. Finally, we propose an implementation of SWG structures to reduce loss and higher order mode excitation between a slab waveguide and a phase array of an array waveguide grating (AWG). Compared to a conventional AWG, the loss is reduced from -1.4 dB to < -0.2 dB at the slab-array interface.
Slab replacement maturity guidelines : [summary].
2014-04-01
Concrete sets in hours at moderate temperatures, : but the bonds that make concrete strong continue : to mature over days to years. However, for : replacement concrete slabs on highways, it is : crucial that concrete develop enough strength : within ...
New Packaging for Amplifier Slabs
Energy Technology Data Exchange (ETDEWEB)
Riley, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thorsness, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Suratwala, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Steele, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rogowski, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2015-03-18
The following memo provides a discussion and detailed procedure for a new finished amplifier slab shipping and storage container. The new package is designed to maintain an environment of <5% RH to minimize weathering.
Tensor-guided fitting of subduction slab depths
Bazargani, Farhad; Hayes, Gavin P.
2013-01-01
Geophysical measurements are often acquired at scattered locations in space. Therefore, interpolating or fitting the sparsely sampled data as a uniform function of space (a procedure commonly known as gridding) is a ubiquitous problem in geophysics. Most gridding methods require a model of spatial correlation for data. This spatial correlation model can often be inferred from some sort of secondary information, which may also be sparsely sampled in space. In this paper, we present a new method to model the geometry of a subducting slab in which we use a data‐fitting approach to address the problem. Earthquakes and active‐source seismic surveys provide estimates of depths of subducting slabs but only at scattered locations. In addition to estimates of depths from earthquake locations, focal mechanisms of subduction zone earthquakes also provide estimates of the strikes of the subducting slab on which they occur. We use these spatially sparse strike samples and the Earth’s curved surface geometry to infer a model for spatial correlation that guides a blended neighbor interpolation of slab depths. We then modify the interpolation method to account for the uncertainties associated with the depth estimates.
A study of coarse mesh collision probability correction factors in slab lattices
International Nuclear Information System (INIS)
Buckler, A.N.
1975-07-01
Calculations of collision probability leakage estimates are performed in one dimensional slab geometry with one neutron group to gain some insight into methods of correction for the coarseness of the mesh H. The chief result is that the correction factor, beta, can be written as CD/H where C → 4 for the diffusion limit. An explicit expression for C is derived in terms of the E 3 function, for a linear flux variation across the slabs. (author)
Topological superfluids confined in a nanoscale slab geometry
Saunders, John
2013-03-01
Nanofluidic samples of superfluid 3He provide a route to explore odd-parity topological superfluids and their surface, edge and defect-bound excitations under well controlled conditions. We have cooled superfluid 3He confined in a precisely defined nano-fabricated cavity to well below 1 mK for the first time. We fingerprint the order parameter by nuclear magnetic resonance, exploiting a SQUID NMR spectrometer of exquisite sensitivity. We demonstrate that dimensional confinement, at length scales comparable to the superfluid Cooper-pair diameter, has a profound influence on the superfluid order of 3He. The chiral A-phase is stabilized at low pressures, in a cavity of height 650 nm. At higher pressures we observe 3He-B with a surface induced planar distortion. 3He-B is a time-reversal invariant topological superfluid, supporting gapless Majorana surface states. In the presence of the small symmetry breaking NMR static magnetic field we observe two possible B-phase states of the order parameter manifold, which can coexist as domains. Non-linear NMR on these states enables a measurement of the surface induced planar distortion, which determines the spectral weight of the surface excitations. The expected structure of the domain walls is such that, at the cavity surface, the line separating the two domains is predicted to host fermion zero modes, protected by symmetry and topology. Increasing confinement should stabilize new p-wave superfluid states of matter, such as the quasi-2D gapped A phase, which breaks time reversal symmetry, has a protected chiral edge mode, and may host half-quantum vortices with a Majorana zero-mode at the core. We discuss experimental progress toward this phase, through measurements on a 100 nm cavity. On the other hand, a cavity height of 1000 nm may stabilize a novel ``striped'' superfluid with spatially modulated order parameter. Supported by EPSRC (UK) GR/J022004/1 and European Microkelvin Consortium, FP7 grant 228464
Non-physical momentum sources in slab geometry gyrokinetics
International Nuclear Information System (INIS)
Parra, Felix I; Catto, Peter J
2010-01-01
We investigate momentum transport in the Hamiltonian electrostatic gyrokinetic formulation of Dubin et al (1983 Phys. Fluids 26 3524). We prove that the long wavelength electric field obtained from the gyrokinetic quasineutrality introduces a non-physical momentum source in the low flow ordering.
International Nuclear Information System (INIS)
Saito, H.; Imamura, A.; Takeuchi, M.; Okamoto, S.; Kasai, Y.; Tsubota, H.; Yoshimura, M.
1993-01-01
The objective of this study was to clarify experimentally and analytically the loading capacities, deformations and failure modes of various types of reinforced concrete structures subjected to loads applied at various loading rates. Flat slabs, slabs with beams and cylindrical walls were tested under static, low-speed and high-speed loading. Analysis was applied to estimate the test results by the finite element method using a layered shell element. The analysis closely simulated the experimental results until punching shear failure occurred. (author)
Rotational flow in tapered slab rocket motors
Saad, Tony; Sams, Oliver C.; Majdalani, Joseph
2006-10-01
Internal flow modeling is a requisite for obtaining critical parameters in the design and fabrication of modern solid rocket motors. In this work, the analytical formulation of internal flows particular to motors with tapered sidewalls is pursued. The analysis employs the vorticity-streamfunction approach to treat this problem assuming steady, incompressible, inviscid, and nonreactive flow conditions. The resulting solution is rotational following the analyses presented by Culick for a cylindrical motor. In an extension to Culick's work, Clayton has recently managed to incorporate the effect of tapered walls. Here, an approach similar to that of Clayton is applied to a slab motor in which the chamber is modeled as a rectangular channel with tapered sidewalls. The solutions are shown to be reducible, at leading order, to Taylor's inviscid profile in a porous channel. The analysis also captures the generation of vorticity at the surface of the propellant and its transport along the streamlines. It is from the axial pressure gradient that the proper form of the vorticity is ascertained. Regular perturbations are then used to solve the vorticity equation that prescribes the mean flow motion. Subsequently, numerical simulations via a finite volume solver are carried out to gain further confidence in the analytical approximations. In illustrating the effects of the taper on flow conditions, comparisons of total pressure and velocity profiles in tapered and nontapered chambers are entertained. Finally, a comparison with the axisymmetric flow analog is presented.
Antibubbles and fine cylindrical sheets of air
Beilharz, D.
2015-08-14
Drops impacting at low velocities onto a pool surface can stretch out thin hemispherical sheets of air between the drop and the pool. These air sheets can remain intact until they reach submicron thicknesses, at which point they rupture to form a myriad of microbubbles. By impacting a higher-viscosity drop onto a lower-viscosity pool, we have explored new geometries of such air films. In this way we are able to maintain stable air layers which can wrap around the entire drop to form repeatable antibubbles, i.e. spherical air layers bounded by inner and outer liquid masses. Furthermore, for the most viscous drops they enter the pool trailing a viscous thread reaching all the way to the pinch-off nozzle. The air sheet can also wrap around this thread and remain stable over an extended period of time to form a cylindrical air sheet. We study the parameter regime where these structures appear and their subsequent breakup. The stability of these thin cylindrical air sheets is inconsistent with inviscid stability theory, suggesting stabilization by lubrication forces within the submicron air layer. We use interferometry to measure the air-layer thickness versus depth along the cylindrical air sheet and around the drop. The air film is thickest above the equator of the drop, but thinner below the drop and up along the air cylinder. Based on microbubble volumes, the thickness of the cylindrical air layer becomes less than 100 nm before it ruptures.
Antibubbles and fine cylindrical sheets of air
Beilharz, D.; Guyon, A.; Li, E. Q.; Thoraval, M.-J.; Thoroddsen, Sigurdur T
2015-01-01
Drops impacting at low velocities onto a pool surface can stretch out thin hemispherical sheets of air between the drop and the pool. These air sheets can remain intact until they reach submicron thicknesses, at which point they rupture to form a myriad of microbubbles. By impacting a higher-viscosity drop onto a lower-viscosity pool, we have explored new geometries of such air films. In this way we are able to maintain stable air layers which can wrap around the entire drop to form repeatable antibubbles, i.e. spherical air layers bounded by inner and outer liquid masses. Furthermore, for the most viscous drops they enter the pool trailing a viscous thread reaching all the way to the pinch-off nozzle. The air sheet can also wrap around this thread and remain stable over an extended period of time to form a cylindrical air sheet. We study the parameter regime where these structures appear and their subsequent breakup. The stability of these thin cylindrical air sheets is inconsistent with inviscid stability theory, suggesting stabilization by lubrication forces within the submicron air layer. We use interferometry to measure the air-layer thickness versus depth along the cylindrical air sheet and around the drop. The air film is thickest above the equator of the drop, but thinner below the drop and up along the air cylinder. Based on microbubble volumes, the thickness of the cylindrical air layer becomes less than 100 nm before it ruptures.
MODOS GUIADOS EM SLABS METAMATERIAIS GUIDED MODES IN METAMATERIAL SLABS
Directory of Open Access Journals (Sweden)
Leonardo André Ambrosio
2006-12-01
Full Text Available Este trabalho apresenta um estudo de revisão de modos propagantes em um guia-de-onda slab constituído de materiais com índices de refração negativo, os chamados metamateriais, Mostra-se que os modos guiados em um slab metamaterial possuem algumas propriedades particulares, tais como a propagação de ondas lentas simétricas ou anti-simétricas, a ausência de modos fundamentais para ondas rápidas e a possibilidade de propagação de ondas guiadas em um meio menos denso. A análise é baseada em expansões de campo no guia e nos espaços superior e inferior ao mesmo.This paper presents a review of the propagation modes in a slab waveguide consisting of negative refraction index materials, known as metamaterials. Some particular properties of guided modes in a metamaterial slab, such as slow symmetric or antisymmetric slow wave propagation, the absence of fundamental modes for fast waves and the possibility of guided waves in a less dense medium. The analysis is based on field expansions in the guide and the upper and lower spaces of it.
Study of global stability of tall buildings with prestressed slabs
Directory of Open Access Journals (Sweden)
L. A. Feitosa
Full Text Available The use of prestressed concrete flat slabs in buildings has been increasing in recent years in the Brazilian market. Since the implementation of tall and slender buildings a trend in civil engineering and architecture fields, arises from the use of prestressed slabs a difficulty in ensuring the overall stability of a building without beams. In order to evaluate the efficiency of the main bracing systems used in this type of building, namely pillars in formed "U" in elevator shafts and stairs, and pillars in which the lengths are significantly larger than their widths, was elaborated a computational models of fictional buildings, which were processed and analyzed using the software CAD/TQS. From the variation of parameters such as: geometry of the pillars, thick slabs, characteristic strength of the concrete, reduceofthe coefficient of inertia for consideration of non-linearities of the physical elements, stiffness of the connections between slabs and pillars, among others, to analyze the influence of these variables on the overall stability of the building from the facing of instability parameter Gama Z, under Brazilian standard NBR 6118, in addition to performing the processing of building using the P-Delta iterative calculation method for the same purpose.
A cylindrical specimen holder for electron cryo-tomography
International Nuclear Information System (INIS)
Palmer, Colin M.; Löwe, Jan
2014-01-01
The use of slab-like flat specimens for electron cryo-tomography restricts the range of viewing angles that can be used. This leads to the “missing wedge” problem, which causes artefacts and anisotropic resolution in reconstructed tomograms. Cylindrical specimens provide a way to eliminate the problem, since they allow imaging from a full range of viewing angles around the tilt axis. Such specimens have been used before for tomography of radiation-insensitive samples at room temperature, but never for frozen-hydrated specimens. Here, we demonstrate the use of thin-walled carbon tubes as specimen holders, allowing the preparation of cylindrical frozen-hydrated samples of ribosomes, liposomes and whole bacterial cells. Images acquired from these cylinders have equal quality at all viewing angles, and the accessible tilt range is restricted only by the physical limits of the microscope. Tomographic reconstructions of these specimens demonstrate that the effects of the missing wedge are substantially reduced, and could be completely eliminated if a full tilt range was used. The overall quality of these tomograms is still lower than that obtained by existing methods, but improvements are likely in future. - Highlights: • The missing wedge is a serious problem for electron cryo-tomography. • Cylindrical specimens allow the missing wedge to be eliminated. • Carbon nanopipettes can be used as cylindrical holders for tomography of frozen-hydrated specimens. • Cryo-tomography of cylindrical biological samples demonstrates a reduction of deleterious effects associated with the missing wedge
Long-life slab replacement concrete : [summary].
2015-04-01
Concrete slab replacement projects in Florida have demonstrated a high incidence of : replacement slab cracking. Causes of cracking have not been reliably determined. University of South Florida researchers : sought to identify the factors or : param...
Generating Atomistic Slab Surfaces with Adsorbates
2017-12-01
slabs of various thickness and with various vacuum spacing need be calculated. This can occur in serial or simultaneously . If performed in serial, the...the user. Although the optimization of the slab thickness and vacuum padding can be done simultaneously , it is more computationally conservative to...monolayer is a slab (True if slab), the type of mesh desired (adsorbates.py was written for “Gamma”), how detailed the mesh should be (in units of inverse
Spread prestressed concrete slab beam bridges.
2015-04-01
TxDOT uses prestressed slab beam bridges for short-span bridges ranging from approximately 3050 ft in : length. These bridges have precast, pretensioned slab beams placed immediately adjacent to one another : with a cast-in-place slab made composi...
Iversen, Birger
1992-01-01
Although it arose from purely theoretical considerations of the underlying axioms of geometry, the work of Einstein and Dirac has demonstrated that hyperbolic geometry is a fundamental aspect of modern physics
Structured cylindrical targets
International Nuclear Information System (INIS)
Arnold, R.
1986-01-01
A variety of experimental concepts using high-energy heavy-ion beams in cylindrical targets have been studied through numerical simulation. With an accelerator planned for GSl, plasma temperatures of 100 eV can be reached by cylindrical compression, using inhomogeneous hollow-shell targets. Magnetic insulation, using external fields, has been explored as an aid in reaching high core temperatures. Experiments on collision-pumped x-ray laser physics are also discussed. (ii) Two-dimensional PlC code simulations of homogeneous solid targets show hydrodynamic effects not found in previous 1-D calculations. (iii) Preliminary ideas for an experiment on non-equilibrium heavy-ion charge-states using an existing accelerator and a pre-formed plasma target are outlined. (author)
Structured cylindrical targets
International Nuclear Information System (INIS)
Arnold, R.; Lackner-Russo, D.; Meyer-ter-Vehn, J.; Hoffmann, I.
1986-01-01
A variety of experimental concepts using high-energy heavy-ion beams in cylindrical targets have been studied through numerical simulation. With an accelerator planned for GSl, plasma temperatures of 100 eV can be reached by cylindrical compression, using inhomogenous hollow-shell targets. Magnetic insulation, using external fields, has been explored as an aid in reaching high core temperatures. Experiments on collision-pumped x-ray laser physics are also discussed. (ii) Two-dimensional PlC code simulations of homogeneous solid targets show hydrodynamic effects not found in previous l-D calculations. (iii) Preliminary ideas for an experiment on non-equilibrium heavy-ion charge-states using an existing accelerator and a pre-formed plasma target are outlined. (author)
van den Broek, P.M.
1984-01-01
The aim of this paper is to give a detailed exposition of the relation between the geometry of twistor space and the geometry of Minkowski space. The paper has a didactical purpose; no use has been made of differential geometry and cohomology.
International Nuclear Information System (INIS)
Wang, L. F.; He, X. T.; Wu, J. F.; Zhang, W. Y.; Ye, W. H.
2013-01-01
A weakly nonlinear (WN) model has been developed for the incompressible Rayleigh-Taylor instability (RTI) in cylindrical geometry. The transition from linear to nonlinear growth is analytically investigated via a third-order solutions for the cylindrical RTI initiated by a single-mode velocity perturbation. The third-order solutions can depict the early stage of the interface asymmetry due to the bubble-spike formation, as well as the saturation of the linear (exponential) growth of the fundamental mode. The WN results in planar RTI [Wang et al., Phys. Plasmas 19, 112706 (2012)] are recovered in the limit of high-mode number perturbations. The difference between the WN growth of the RTI in cylindrical geometry and in planar geometry is discussed. It is found that the interface of the inward (outward) development spike/bubble is extruded (stretched) by the additional inertial force in cylindrical geometry compared with that in planar geometry. For interfaces with small density ratios, the inward growth bubble can grow fast than the outward growth spike in cylindrical RTI. Moreover, a reduced formula is proposed to describe the WN growth of the RTI in cylindrical geometry with an acceptable precision, especially for small-amplitude perturbations. Using the reduced formula, the nonlinear saturation amplitude of the fundamental mode and the phases of the Fourier harmonics are studied. Thus, it should be included in applications where converging geometry effects play an important role, such as the supernova explosions and inertial confinement fusion implosions.
Method for Bubbledeck Concrete Slab with Gaps
Directory of Open Access Journals (Sweden)
Sergiu Călin
2009-01-01
Full Text Available The composite slabs are made of BubbleDeck type slab elements with spherical gaps, poured in place on transversal and longitudinal directions. By introducing the gaps leads to a 30...50\\% lighter slab which reduces the loads on the columns, walls and foundations, and of course of the entire building. BubbleDeck slab elements are plates with ribs on two directions made of reinforced concrete or precast concrete with spherical shaped bubbles. These slab elements have a bottom and an upper concrete part connected with vertical ribs that go around the gaps.
Exposure buildup factors for a cobalt-60 point isotropic source for single and two layer slabs
International Nuclear Information System (INIS)
Chakarova, R.
1992-01-01
Exposure buildup factors for point isotropic cobalt-60 sources are calculated by the Monte Carlo method with statistical errors ranging from 1.5 to 7% for 1-5 mean free paths (mfp) thick water and iron single slabs and for 1 and 2 mfp iron layers followed by water layers 1-5 mfp thick. The computations take into account Compton scattering. The Monte Carlo data for single slab geometries are approximated by Geometric Progression formula. Kalos's formula using the calculated single slab buildup factors may be applied to reproduce the data for two-layered slabs. The presented results and discussion may help when choosing the manner in which the radiation field gamma irradiation units will be described. (author)
Linear simulations of the cylindrical Richtmyer-Meshkov instability in magnetohydrodynamics
Bakhsh, Abeer; Gao, Song; Samtaney, Ravi; Wheatley, V.
2016-01-01
fusion and suppression by means of a magnetic field, we investigate the RMI via linear MHD simulations in cylindrical geometry. The physical setup is that of a Chisnell-type converging shock interacting with a density interface with either axial
Friction Compensation in the Upsetting of Cylindrical Test Specimens
DEFF Research Database (Denmark)
Christiansen, Peter; Martins, P. A. F.; Bay, Niels Oluf
2016-01-01
This manuscript presents a combined numerical andexperimental methodology for determining the stress-straincurve of metallic materials from the measurements of forceand displacement obtained in the axial compression of cylindrical test specimens with friction between the specimens and the platens....... The methodology is based on minimizing the errorbetween the average surface pressure obtained from the experimental measurements of the force and displacement and thatobtained from the slab method of analysis of metal plasticity.Three different friction models based on Coulomb friction, the constant friction...... model or combined friction models are utilized .Experimental results obtained from cylindrical and Rastegaev test specimens with different lubricants combined with the experimental determination of friction by means of ring compression tests allows compensating the effect of friction...
Surface behaviour of the pairing gap in a slab of nuclear matter
International Nuclear Information System (INIS)
Baldo, M.; Farine, M.; Lombardo, U.; Saperstein, E.E.; Zverev, M.V.; Schuck, P.
2003-01-01
The surface behavior of the pairing gap previously studied for semi-infinite nuclear matter is analyzed in the slab geometry. The gap-shape function is calculated in two cases: a) pairing with the Gogny force in a hard-wall potential and b) pairing with the separable Paris interaction in a Saxon-Woods mean-field potential. It is shown that the surface features are preserved in the case of slab geometry, being almost independent of the width of the slab. It is also demonstrated that the surface enhancement is strengthened as the absolute value of chemical potential vertical stroke μvertical stroke decreases which simulates the approach to the nucleon drip line. (orig.)
Cylindric-like algebras and algebraic logic
Ferenczi, Miklós; Németi, István
2013-01-01
Algebraic logic is a subject in the interface between logic, algebra and geometry, it has strong connections with category theory and combinatorics. Tarski’s quest for finding structure in logic leads to cylindric-like algebras as studied in this book, they are among the main players in Tarskian algebraic logic. Cylindric algebra theory can be viewed in many ways: as an algebraic form of definability theory, as a study of higher-dimensional relations, as an enrichment of Boolean Algebra theory, or, as logic in geometric form (“cylindric” in the name refers to geometric aspects). Cylindric-like algebras have a wide range of applications, in, e.g., natural language theory, data-base theory, stochastics, and even in relativity theory. The present volume, consisting of 18 survey papers, intends to give an overview of the main achievements and new research directions in the past 30 years, since the publication of the Henkin-Monk-Tarski monographs. It is dedicated to the memory of Leon Henkin.
Preface: Deep Slab and Mantle Dynamics
Suetsugu, Daisuke; Bina, Craig R.; Inoue, Toru; Wiens, Douglas A.
2010-11-01
We are pleased to publish this special issue of the journal Physics of the Earth and Planetary Interiors entitled "Deep Slab and Mantle Dynamics". This issue is an outgrowth of the international symposium "Deep Slab and Mantle Dynamics", which was held on February 25-27, 2009, in Kyoto, Japan. This symposium was organized by the "Stagnant Slab Project" (SSP) research group to present the results of the 5-year project and to facilitate intensive discussion with well-known international researchers in related fields. The SSP and the symposium were supported by a Grant-in-Aid for Scientific Research (16075101) from the Ministry of Education, Culture, Sports, Science and Technology of the Japanese Government. In the symposium, key issues discussed by participants included: transportation of water into the deep mantle and its role in slab-related dynamics; observational and experimental constraints on deep slab properties and the slab environment; modeling of slab stagnation to constrain its mechanisms in comparison with observational and experimental data; observational, experimental and modeling constraints on the fate of stagnant slabs; eventual accumulation of stagnant slabs on the core-mantle boundary and its geodynamic implications. This special issue is a collection of papers presented in the symposium and other papers related to the subject of the symposium. The collected papers provide an overview of the wide range of multidisciplinary studies of mantle dynamics, particularly in the context of subduction, stagnation, and the fate of deep slabs.
Rodger, Alison
1995-01-01
Molecular Geometry discusses topics relevant to the arrangement of atoms. The book is comprised of seven chapters that tackle several areas of molecular geometry. Chapter 1 reviews the definition and determination of molecular geometry, while Chapter 2 discusses the unified view of stereochemistry and stereochemical changes. Chapter 3 covers the geometry of molecules of second row atoms, and Chapter 4 deals with the main group elements beyond the second row. The book also talks about the complexes of transition metals and f-block elements, and then covers the organometallic compounds and trans
The slab albedo problem for the triplet scattering kernel with modified F{sub N} method
Energy Technology Data Exchange (ETDEWEB)
Tuereci, Demet [Ministry of Education, 75th year Anatolia High School, Ankara (Turkey)
2016-12-15
One speed, time independent neutron transport equation for a slab geometry with the quadratic anisotropic scattering kernel is considered. The albedo and transmission factor are calculated by the modified F{sub N} method. The obtained numerical results are listed for different scattering coefficients.
The effects of rheological decoupling on slab deformation in the Earth's upper mantle
Androvičová, A.; Čížková, H.; van den Berg, A.
2013-01-01
Processes within subduction zones have a major influence on the plate dynamics and mantle convection. Subduction is controlled by a combination of many parameters and there is no simple global relationship between the resulting slab geometry and deformation and any specific subduction parameter.
International Nuclear Information System (INIS)
Mihalczo, J.T.; Blakeman, E.D.; Ragan, G.E.; Kryter, R.C.; Robinson, R.C.; Seino, H.
1987-08-01
In order to study nuclear criticality safety related to the development of fast breeder technology, 252 Cf-source-driven neutron noise analysis measurements were performed with a Pu-U nitrate solution in a slab tank of various heights and thickness varying 11.43 cm to 19.05 cm. The results and conclusions of these experiments are (1) a capability to measure the subcriticality of a multiplying system of slab geometry to a k/sub eff/ as low as 0.7 was demonstrated, (2) calculated neutron multiplication factors agreed with those from the experiments within ∼0.02, and (3) the applicability of the method for plutonium solution systems was demonstrated. This paper describes measurements in which the height of the slab was varied for a fixed thickness and the thickness varied for a fixed height, which are the first applications of this measurement method to slab geometry
Application of the cylindrically guided wave technique for bolt and pump shaft inspections
International Nuclear Information System (INIS)
Light, G.M.; Ruescher, E.H.; Bloom, E.A.; Joshi, N.R.; Tsai, Y.M.; Liu, S.N.
1993-01-01
Elastic wave propagation in a bounded medium significantly differs from that in an unbounded medium. The bounded medium in the form of a cylinder acts like a solid waveguide directing the wave with its geometry. A continuous or a pulsed wave interacts with cylindrical boundaries producing mode-converted signals in addition to the backwall echo. The signals are received at constant time intervals directly proportional to the diameter of a solid cylindrical object such as a bolt or an anchor stud. The Cylindrically Guided Wave Technique (CGWT) makes intelligent use of the mode-converted signals, or trailing pulses, to detect corrosion wastages and cracks in cylindrical objects. (orig.)
International Nuclear Information System (INIS)
Robinson, I.; Trautman, A.
1988-01-01
The geometry of classical physics is Lorentzian; but weaker geometries are often more appropriate: null geodesics and electromagnetic fields, for example, are well known to be objects of conformal geometry. To deal with a single null congruence, or with the radiative electromagnetic fields associated with it, even less is needed: flag geometry for the first, optical geometry, with which this paper is chiefly concerned, for the second. The authors establish a natural one-to-one correspondence between optical geometries, considered locally, and three-dimensional Cauchy-Riemann structures. A number of Lorentzian geometries are shown to be equivalent from the optical point of view. For example the Goedel universe, the Taub-NUT metric and Hauser's twisting null solution have an optical geometry isomorphic to the one underlying the Robinson congruence in Minkowski space. The authors present general results on the problem of lifting a CR structure to a Lorentz manifold and, in particular, to Minkowski space; and exhibit the relevance of the deviation form to this problem
International Nuclear Information System (INIS)
Mansur, Ralph S.; Barros, Ricardo C.
2011-01-01
We describe a method to determine the neutron scalar flux in a slab using monoenergetic diffusion model. To achieve this goal we used three ingredients in the computational code that we developed on the Scilab platform: a spectral nodal method that generates numerical solution for the one-speed slab-geometry fixed source diffusion problem with no spatial truncation errors; a spatial reconstruction scheme to yield detailed profile of the coarse-mesh solution; and an angular reconstruction scheme to yield approximately the neutron angular flux profile at a given location of the slab migrating in a given direction. Numerical results are given to illustrate the efficiency of the offered code. (author)
Formation of vortex breakdown in conical–cylindrical cavities
International Nuclear Information System (INIS)
Martins, Diego Alves de Moro; Souza, Francisco José de; Salvo, Ricardo de Vasconcelos
2014-01-01
Highlights: • Rotating flows in conical–cylindrical cavities were simulated via an in-house code using unstructured meshes. • The vortex breakdown phenomenon was verified in the geometries analyzed. • The influence of Stewartson and Bödewadt layers was observed in the vortex breakdown formation. • A curve of stability and number of breakdowns was obtained as a function of Reynolds number. • Spiral vortex breakdown was observed in some situations. - Abstract: Numerical simulations in confined rotating flows were performed in this work, in order to verify and characterize the formation of the vortex breakdown phenomenon. Cylindrical and conical–cylindrical geometries, both closed, were used in the simulations. The rotating flow is induced by the bottom wall, which rotates at constant angular velocity. Firstly the numerical results were compared to experimental results available in references, with the purpose to verify the capacity of the computational code to predict the vortex breakdown phenomenon. Further, several simulations varying the parameters which govern the characteristics of the flows analyzed in this work, i.e., the Reynolds number and the aspect ratio, were performed. In these simulations, the limits for the transitional regime and the vortex breakdown formation were verified. Steady and transient cases, with and without turbulence modeling, were simulated. In general, some aspects of the process of vortex breakdown in conical–cylindrical geometries were observed to be different from that in cylinders
Surface correlation effects in two-band strongly correlated slabs.
Esfahani, D Nasr; Covaci, L; Peeters, F M
2014-02-19
Using an extension of the Gutzwiller approximation for an inhomogeneous system, we study the two-band Hubbard model with unequal band widths for a slab geometry. The aim is to investigate the mutual effect of individual bands on the spatial distribution of quasi-particle weight and charge density, especially near the surface of the slab. The main effect of the difference in band width is the presence of two different length scales corresponding to the quasi-particle profile of each band. This is enhanced in the vicinity of the critical interaction of the narrow band where an orbitally selective Mott transition occurs and a surface dead layer forms for the narrow band. For the doped case, two different regimes of charge transfer between the surface and the bulk of the slab are revealed. The charge transfer from surface/center to center/surface depends on both the doping level and the average relative charge accumulated in each band. Such effects could also be of importance when describing the accumulation of charges at the interface between structures made of multi-band strongly correlated materials.
From stripe to slab confinement for DNA linearization in nanochannels
Cifra, Peter; Benkova, Zuzana; Namer, Pavol
We investigate suggested advantageous analysis in the linearization experiments with macromolecules confined in a stripe-like channel using Monte Carlo simulations. The enhanced chain extension in a stripe that is due to significant excluded volume interactions between monomers in two dimensions weakens on transition to experimentally feasible slit-like channel. Based on the chain extension-confinement strength dependence and the structure factor behavior for the chain in stripe we infer the excluded volume regime typical for two-dimensional systems. On transition to the slab geometry, the advantageous chain extension decreases and the Gaussian regime is observed for not very long semiflexible chains. The evidence for pseudo-ideality in confined chains is based on indicators such as the extension curves, variation of the extension with the persistence length or the structure factor. The slab behavior is observed when the stripe (originally of monomer thickness) reaches the thickness larger than cca 10nm in the third dimension. This maximum height of the slab to retain the advantage of the stripe is very low and this have implication for DNA linearization experiments. The presented analysis, however, has a broader relevance for confined polymers. Support from Slovak R&D Agency (SRDA-0451-11) is acknowledged.
The Green's function method for critical heterogeneous slabs
International Nuclear Information System (INIS)
Kornreich, D.E.
1996-01-01
Recently, the Green's Function Method (GFM) has been employed to obtain benchmark-quality results for nuclear engineering and radiative transfer calculations. This was possible because of fast and accurate calculations of the Green's function and the associated Fourier and Laplace transform inversions. Calculations have been provided in one-dimensional slab geometries for both homogeneous and heterogeneous media. A heterogeneous medium is analyzed as a series of homogeneous slabs, and Placzek's lemma is used to extend each slab to infinity. This allows use of the infinite medium Green's function (the anisotropic plane source in an infinite homogeneous medium) in the solution. To this point, a drawback of the GFM has been the limitation to media with c 1; however, mathematical solutions exist which result in oscillating Green's functions. Such calculations are briefly discussing. The limitation to media with c < 1 has been relaxed so that the Green's function may also be calculated for media with c ≥ 1. Thus, materials that contain fissionable isotopes may be modeled
Calibrating a large slab vessel: A battle of the bulge
International Nuclear Information System (INIS)
Thomas, I.R.
1993-01-01
Slab tanks (critically-safe-by-geometry vessels) were proposed for the storage of concentrated, highly-enriched uranium solution in the design of the Fuel Processing Restoration (FPR) Facility at the Idaho Chemical Processing Plant (ICPP). Currently, measurements of bulk mass in ICPP annular vessels have standard deviations on the order of 0.2%, or less. ICPP personnel felt that their inexperience with the aforementioned expansions would prevent them from attaining comparable precision with slab tanks. To help assess the measurement accuracy of slab vessels, a full-scale mockup of those proposed for the FPR Facility was installed for test calibrations. These calibrations were designed to detect vessel expansion under differing conditions. This paper will compare the base-line, water calibrations with those of the higher-density aluminum nitrate, and any observed deflection will be described using vessel calibration techniques. The calibration using water at an elevated temperature was not performed due to the difficulty of maintaining the elevated temperature. This calibration probably will not be conducted because the construction of the FPR Facility has been halted
Pottmann, Helmut; Eigensatz, Michael; Vaxman, Amir; Wallner, Johannes
2014-01-01
Around 2005 it became apparent in the geometry processing community that freeform architecture contains many problems of a geometric nature to be solved, and many opportunities for optimization which however require geometric understanding. This area of research, which has been called architectural geometry, meanwhile contains a great wealth of individual contributions which are relevant in various fields. For mathematicians, the relation to discrete differential geometry is significant, in particular the integrable system viewpoint. Besides, new application contexts have become available for quite some old-established concepts. Regarding graphics and geometry processing, architectural geometry yields interesting new questions but also new objects, e.g. replacing meshes by other combinatorial arrangements. Numerical optimization plays a major role but in itself would be powerless without geometric understanding. Summing up, architectural geometry has become a rewarding field of study. We here survey the main directions which have been pursued, we show real projects where geometric considerations have played a role, and we outline open problems which we think are significant for the future development of both theory and practice of architectural geometry.
Pottmann, Helmut
2014-11-26
Around 2005 it became apparent in the geometry processing community that freeform architecture contains many problems of a geometric nature to be solved, and many opportunities for optimization which however require geometric understanding. This area of research, which has been called architectural geometry, meanwhile contains a great wealth of individual contributions which are relevant in various fields. For mathematicians, the relation to discrete differential geometry is significant, in particular the integrable system viewpoint. Besides, new application contexts have become available for quite some old-established concepts. Regarding graphics and geometry processing, architectural geometry yields interesting new questions but also new objects, e.g. replacing meshes by other combinatorial arrangements. Numerical optimization plays a major role but in itself would be powerless without geometric understanding. Summing up, architectural geometry has become a rewarding field of study. We here survey the main directions which have been pursued, we show real projects where geometric considerations have played a role, and we outline open problems which we think are significant for the future development of both theory and practice of architectural geometry.
A vibrating wire parallel to a high temperature superconducting slab. Vol. 2
Energy Technology Data Exchange (ETDEWEB)
Saif, A G; El-sabagh, M A [Department of Mathematic and Theoretical physics, Nuclear Research Center, Atomic Energy Authority, Cairo (Egypt)
1996-03-01
The power losses problem for an idealized high temperature type II superconducting system of a simple geometry is studied. This system is composed of a vibrating normal conducting wire (two wires) carrying a direct current parallel to an uniaxial anisotropic type II superconducting slab (moving slab). First, the electromagnetic equation governing the dynamics of this system, and its solutions are obtained. Secondly, a modified anisotropic london equation is developed to study these systems in the case of the slab moving. Thirdly, it is found that, the power losses is dependent on the frequency, london penetration depth, permeability, conductivity, velocity, and the distance between the normal conductors and the surfaces of the superconducting slab. Moreover, the power losses decreases as the distance between the normal conductors and the surface of the superconducting slab decreases; and increases as the frequency, the london penetration depth, permeability, conductivity, and velocity are increased. These losses along the versor of the anisotropy axis is increased as {lambda}{sub |}| increases. Moreover, it is greater than the power losses along the crystal symmetry direction. In the isotropic case as well as the slab thickness tends to infinity, agreement with previous results are obtained. 2 figs.
2013-05-01
Based on a recent study on cost efficient alternative bridge approach slab (BAS) designs (Thiagarajan et : al. 2010) has recommended three new BAS designs for possible implementation by MoDOT namely a) 20 feet cast-inplace : slab with sleeper slab (C...
Maor, Eli
2014-01-01
If you've ever thought that mathematics and art don't mix, this stunning visual history of geometry will change your mind. As much a work of art as a book about mathematics, Beautiful Geometry presents more than sixty exquisite color plates illustrating a wide range of geometric patterns and theorems, accompanied by brief accounts of the fascinating history and people behind each. With artwork by Swiss artist Eugen Jost and text by acclaimed math historian Eli Maor, this unique celebration of geometry covers numerous subjects, from straightedge-and-compass constructions to intriguing configur
Vertical slab sinking and westward subduction offshore of Mesozoic North America
Sigloch, Karin; Mihalynuk, Mitchell G.
2013-04-01
Subducted slabs in the mantle, as imaged by seismic tomography, preserve a record of ancient subduction zones. Ongoing debate concerns how direct this link is. How long ago did each parcel of slab subduct, and where was the trench located relative to the imaged slab position? Resolving these questions will benefit paleogeographic reconstructions, and restrict the range of plausible rheologies for mantle convection simulations. We investigate one of the largest and best-constrained Mesozoic slab complexes, the "Farallon" in the transition zone and lower mantle beneath North America. We quantitatively integrate observations from whole-mantle P-wave tomography, global plate reconstructions, and land geological evidence from the North American Cordillera. These three data sets permit us to test the simplest conceivable hypothesis for linking slabs to paleo-trenches: that each parcel of slab sank only vertically shortly after entering the trench That is, we test whether within the limits of tomographic resolution, all slab material lies directly below the location where it subducted beneath its corresponding arc. Crucially and in contrast to previous studies, we do not accept or impose an Andean-style west coast trench (Farallon-beneath-continent subduction) since Jurassic times, as this scenario is inconsistent with many geological observations. Slab geometry alone suggests that trenches started out as intra-oceanic because tomography images massive, linear slab "walls" in the lower mantle, extending almost vertically from about 800 km to 2000+ km depth. Such steep geometries would be expected from slabs sinking vertically beneath trenches that were quasi-stationary over many tens of millions of years. Intra-oceanic trenches west of Mesozoic North America could have been stationary, whereas a coastal Farallon trench could not, because the continent moved westward continuously as the Atlantic opened. Overlap of North American west-coast positions, as reconstructed in a
Kemnitz, Arnfried
Der Grundgedanke der Analytischen Geometrie besteht darin, dass geometrische Untersuchungen mit rechnerischen Mitteln geführt werden. Geometrische Objekte werden dabei durch Gleichungen beschrieben und mit algebraischen Methoden untersucht.
Lefschetz, Solomon
2005-01-01
An introduction to algebraic geometry and a bridge between its analytical-topological and algebraical aspects, this text for advanced undergraduate students is particularly relevant to those more familiar with analysis than algebra. 1953 edition.
Ay, Nihat; Lê, Hông Vân; Schwachhöfer, Lorenz
2017-01-01
The book provides a comprehensive introduction and a novel mathematical foundation of the field of information geometry with complete proofs and detailed background material on measure theory, Riemannian geometry and Banach space theory. Parametrised measure models are defined as fundamental geometric objects, which can be both finite or infinite dimensional. Based on these models, canonical tensor fields are introduced and further studied, including the Fisher metric and the Amari-Chentsov tensor, and embeddings of statistical manifolds are investigated. This novel foundation then leads to application highlights, such as generalizations and extensions of the classical uniqueness result of Chentsov or the Cramér-Rao inequality. Additionally, several new application fields of information geometry are highlighted, for instance hierarchical and graphical models, complexity theory, population genetics, or Markov Chain Monte Carlo. The book will be of interest to mathematicians who are interested in geometry, inf...
Randrianalisoa, Jaona; Haussener, Sophia; Baillis, Dominique; Lipiński, Wojciech
2017-11-01
Radiative heat transfer is analyzed in participating media consisting of long cylindrical fibers with a diameter in the limit of geometrical optics. The absorption and scattering coefficients and the scattering phase function of the medium are determined based on the discrete-level medium geometry and optical properties of individual fibers. The fibers are assumed to be randomly oriented and positioned inside the medium. Two approaches are employed: a volume-averaged two-intensity approach referred to as multi-RTE approach and a homogenized single-intensity approach referred to as the single-RTE approach. Both approaches require effective properties, determined using direct Monte Carlo ray tracing techniques. The macroscopic radiative transfer equations (for single intensity or two volume-averaged intensities) with the corresponding effective properties are solved using Monte Carlo techniques and allow for the determination of the radiative flux distribution as well as overall transmittance and reflectance of the medium. The results are compared against predictions by the direct Monte Carlo simulation on the exact morphology. The effects of fiber volume fraction and optical properties on the effective radiative properties and the overall slab radiative characteristics are investigated. The single-RTE approach gives accurate predictions for high porosity fibrous media (porosity about 95%). The multi-RTE approach is recommended for isotropic fibrous media with porosity in the range of 79-95%.
Slab Penetration vs. Slab Stagnation: Mantle Reflectors as an Indicator
Okeler, A.; Gu, Y. J.; Schultz, R.; Contenti, S. M.
2011-12-01
Subducting oceanic lithosphere along convergent margins may stagnate near the base of the upper mantle or penetrate into the lower mantle. These dynamic processes cause extensive thermal and compositional variations, which can be observed in terms of impedance contrast (reflectivity) and topography of mantle transition zone (MTZ) discontinuities, i.e., 410- and 660-km discontinuities. In this study, we utilize ~ 15000 surface-reflected shear waves (SS) and their precursory arrivals (S410S and S660S) to analyze subduction related deformations on mantle reflectivity structure. We apply pre-stack, time-to-depth migration technique to SS precursors, and move weak underside reflections using PREM-predicted travel-time curves. Common Mid-point gathers are formed to investigate structure under the western Pacific, south America, and Mediterranean convergent boundaries. In general, mantle reflectivity structures are consistent with previous seismic tomography models. In regions of slab penetration (e.g., southern Kurile arc, Aegean Sea), our results show 1) a substantial decrease in S660S amplitude, and 2) strong lower mantle reflector(s) at ~ 900 km depth. These reflective structures are supported by zones of high P and S velocities extending into the lower mantle. Our 1-D synthetic simulations suggest that the decreasing S660S amplitudes are, at least partially, associated with shear wave defocusing due to changes in reflector depth (by ±20 km) within averaging bin. Assuming a ~500 km wide averaging area, a dipping reflector with 6-8 % slope can reduce the amplitude of a SS precursor by ~50%. On the other hand, broad depressions with strong impedance contrast at the base of the MTZ characterize the regions of slab stagnation, such as beneath the Tyrrhenian Sea and northeastern China. For the latter region, substantial topography on the 660-km discontinuity west of the Wadati-Benioff zone suggests that the stagnant part of the Pacific plate across Honshu arc is not
Air slab-correction for Γ-ray attenuation measurements
Mann, Kulwinder Singh
2017-12-01
Gamma (γ)-ray shielding behaviour (GSB) of a material can be ascertained from its linear attenuation coefficient (μ, cm-1). Narrow-beam transmission geometry is required for μ-measurement. In such measurements, a thin slab of the material has to insert between point-isotropic γ-ray source and detector assembly. The accuracy in measurements requires that sample's optical thickness (OT) remain below 0.5 mean free path (mfp). Sometimes it is very difficult to produce thin slab of sample (absorber), on the other hand for thick absorber, i.e. OT >0.5 mfp, the influence of the air displaced by it cannot be ignored during μ-measurements. Thus, for a thick sample, correction factor has been suggested which compensates the air present in the transmission geometry. The correction factor has been named as an air slab-correction (ASC). Six samples of low-Z engineering materials (cement-black, clay, red-mud, lime-stone, cement-white and plaster-of-paris) have been selected for investigating the effect of ASC on μ-measurements at three γ-ray energies (661.66, 1173.24, 1332.50 keV). The measurements have been made using point-isotropic γ-ray sources (Cs-137 and Co-60), NaI(Tl) detector and multi-channel-analyser coupled with a personal computer. Theoretical values of μ have been computed using a GRIC2-toolkit (standardized computer programme). Elemental compositions of the samples were measured with Wavelength Dispersive X-ray Fluorescence (WDXRF) analyser. Inter-comparison of measured and computed μ-values, suggested that the application of ASC helps in precise μ-measurement for thick samples of low-Z materials. Thus, this hitherto widely ignored ASC factor is recommended to use in similar γ-ray measurements.
Contribution to the study of slab thickness
International Nuclear Information System (INIS)
Moraitis, G.A.; Rorris, G.P.
1978-01-01
A method is proposed for calculating the time-independent values of the equivalent slab thickness of the ionosphere, defined as the ratio of the total electron content to the corresponding maximum electron density of the F region. Periodic variations of slab thickness are studied and are correlated to relative changes in exospheric temperature, deduced from the OGO-6 model
Repairing reinforced concrete slabs using composite layers
International Nuclear Information System (INIS)
Naghibdehi, M. Ghasemi; Sharbatdar, M.K.; Mastali, M.
2014-01-01
There are several strengthening methods for rehabilitation of RC structural elements. The efficiency of these methods has been demonstrated by many researchers. Due to their mechanical properties, using fibrous materials in rehabilitation applications is growing fast. Therefore, this study presents rehabilitation of slabs in such a way that plain concrete layers on top, on bottom, on the entire cross section are replaced by reinforced concrete layers. In order to reinforce the concrete, Polypropylene (PP) and steel fibers were used by 0.5%, 1% and 2% fiber volume fractions. Nineteen slabs were studied under flexural loadings and fibrous material effects on the initial crack force, the maximum loading carrying capacity, absorbed energy and ductility were investigated. The obtained results demonstrated that increasing the fiber volume fraction or using reinforced concrete layer on top, bottom, or at the entire cross section of the slabs not only always leads to improvement in the slab performance, but also sometimes debilitates the slab performance. Hence, this study will propose the best positioning of reinforced concrete layer, fiber volume fraction and fiber type to achieve the best flexural performance of slabs. - Highlights: • Using PP fibers at the bottom layer led to the best slab performance in bending. • Using steel fiber at the top layer and entire cross-section led to the best slab performance. • Maximum increase in the initial crack force and loading were obtained at 2% steel fiber. • Maximum increase in the initial crack force and loading were obtained at 1% PP fiber
0-6722 : spread prestressed concrete slab beam bridges.
2014-08-01
The Texas Department of Transportation uses : precast prestressed concrete slab beam bridges for : shorter-span bridges of approximately 3050 ft in : length. Conventional slab beam bridges have slab : beams placed immediately adjacent to one anoth...
Shearfree cylindrical gravitational collapse
International Nuclear Information System (INIS)
Di Prisco, A.; Herrera, L.; MacCallum, M. A. H.; Santos, N. O.
2009-01-01
We consider diagonal cylindrically symmetric metrics, with an interior representing a general nonrotating fluid with anisotropic pressures. An exterior vacuum Einstein-Rosen spacetime is matched to this using Darmois matching conditions. We show that the matching conditions can be explicitly solved for the boundary values of metric components and their derivatives, either for the interior or exterior. Specializing to shearfree interiors, a static exterior can only be matched to a static interior, and the evolution in the nonstatic case is found to be given in general by an elliptic function of time. For a collapsing shearfree isotropic fluid, only a Robertson-Walker dust interior is possible, and we show that all such cases were included in Cocke's discussion. For these metrics, Nolan and Nolan have shown that the matching breaks down before collapse is complete, and Tod and Mena have shown that the spacetime is not asymptotically flat in the sense of Berger, Chrusciel, and Moncrief. The issues about energy that then arise are revisited, and it is shown that the exterior is not in an intrinsic gravitational or superenergy radiative state at the boundary.
The cylindrical GEM detector of the KLOE-2 experiment
International Nuclear Information System (INIS)
Bencivenni, G.; Ciambrone, P.; De Lucia, E.; Domenici, D.; Felici, G.; Fermani, P.; Morello, G.; Branchini, P.; Cicco, A. Di; Czerwinski, E.
2017-01-01
The KLOE-2 experiment started its data taking campaign in November 2014 with an upgraded tracking system at the DAΦNE electron-positron collider at the Frascati National Laboratory of INFN. The new tracking device, the Inner Tracker, operated together with the KLOE-2 Drift Chamber, has been installed to improve track and vertex reconstruction capabilities of the experimental apparatus. The Inner Tracker is a cylindrical GEM detector composed of four cylindrical triple-GEM detectors, each provided with an X-V strips-pads stereo readout. Although GEM detectors are already used in high energy physics experiments, this device is considered a frontier detector due to its fully-cylindrical geometry: KLOE-2 is the first experiment benefiting of this novel detector technology. Alignment and calibration of this detector will be presented together with its operating performance and reconstruction capabilities.
Using thermal and compositional modeling to assess the role of water in Alaskan flat slab subduction
Robinson, S. E.; Porter, R. C.; Hoisch, T. D.
2017-12-01
Although plate tectonic theory is well established in the geosciences, the mechanisms and details of various plate-tectonics related phenomena are not always well understood. In some ( 10%) convergent plate boundaries, subduction of downgoing oceanic plates is characterized by low angle geometries and is termed "flat slab subduction." The mechanism(s) driving this form of subduction are not well understood. The goal of this study is to explore the role that water plays in these flat slab subduction settings. This is important for a better understanding of the behavior of these systems and for assessing volcanic hazards associated with subduction and slab rollback. In southern Alaska, the Pacific Plate is subducting beneath the North American plate at a shallow angle. This low-angle subduction within the region is often attributed to the subduction of the Yakutat block, a terrane accreting to the south-central coast of Alaska. This flat slab region is bounded by the Aleution arc to the west and the strike-slip Queen Charlotte fault to the east. Temperature and compositional models for a 500-km transect across this subduction zone in Alaska were run for ten million years (the length of time that flat slab subduction has been ongoing in Alaska) and allow for interpretation of present-day conditions at depth. This allows for an evaluation of two hypotheses regarding the role of water in flat-slab regions: (1) slab hydration and dehydration help control slab buoyancy which influences whether flat slab subduction will be maintained or ended. (2) slab hydration/dehydration of the overlying lithosphere impacts deformation within the upper plate as water encourages plate deformation. Preliminary results from thermal modeling using Thermod8 show that cooling of the mantle to 500 °C is predicted down to 100 km depth at 10 million years after the onset of low-angle subduction (representing present-day). Results from compositional modeling in Perple_X show the maximum amount
International Nuclear Information System (INIS)
Ionin, Andrei A; Kozlov, A Yu; Seleznev, L V; Sinitsyn, D V
2009-01-01
A compact capacitive transverse RF-discharge-pumped slab CO laser with cryogenically cooled electrodes, which operates both in the cw and repetitively pulsed regimes, is fabricated. The laser operation is studied in the free running multifrequency regime at the vibrational - rotational transitions of the fundamental (V + 1 → V) vibrational bands of the CO molecule in the spectral region from 5.1 to 5.4 μm. Optimal operation conditions (gas mixture composition and pressure, RF pump parameters) are determined. It is shown that only gas mixtures with a high content of oxygen (up to 20% with respect to the concentration of CO molecules) can be used as an active medium of this laser. It is demonstrated that repetitively pulsed pumping is more efficient compared to cw pumping. In this case, quasi-cw lasing regime can be obtained. The maximum average output power of ∼12 W was obtained for this laser operating on fundamental bands and its efficiency achieved ∼14 %. The frequency-selective operation regime of the slab RF-discharge-pumped CO laser was realised at ∼ 100 laser lines in the spectral region from 5.0 to 6.5 μm with the average output power of up to several tens of milliwatts in each line. Lasing at the transitions of the first vibrational overtone (V + 2 → V) of the CO molecule is obtained in the spectral region from 2.5 to 3.9 μm. The average output power of the overtone laser achieved 0.3 W. All the results were obtained without the forced gas mixture exchange in the discharge chamber. Under fixed experimental conditions, repetitively pulsed lasing (with fluctuations of the output characteristics no more than ±10 %) was stable for more than an hour. (lasers)
Burdette, A C
1971-01-01
Analytic Geometry covers several fundamental aspects of analytic geometry needed for advanced subjects, including calculus.This book is composed of 12 chapters that review the principles, concepts, and analytic proofs of geometric theorems, families of lines, the normal equation of the line, and related matters. Other chapters highlight the application of graphing, foci, directrices, eccentricity, and conic-related topics. The remaining chapters deal with the concept polar and rectangular coordinates, surfaces and curves, and planes.This book will prove useful to undergraduate trigonometric st
Berger, Marcel
2010-01-01
Both classical geometry and modern differential geometry have been active subjects of research throughout the 20th century and lie at the heart of many recent advances in mathematics and physics. The underlying motivating concept for the present book is that it offers readers the elements of a modern geometric culture by means of a whole series of visually appealing unsolved (or recently solved) problems that require the creation of concepts and tools of varying abstraction. Starting with such natural, classical objects as lines, planes, circles, spheres, polygons, polyhedra, curves, surfaces,
Robinson, Gilbert de B
2011-01-01
This brief undergraduate-level text by a prominent Cambridge-educated mathematician explores the relationship between algebra and geometry. An elementary course in plane geometry is the sole requirement for Gilbert de B. Robinson's text, which is the result of several years of teaching and learning the most effective methods from discussions with students. Topics include lines and planes, determinants and linear equations, matrices, groups and linear transformations, and vectors and vector spaces. Additional subjects range from conics and quadrics to homogeneous coordinates and projective geom
Connes, Alain
1994-01-01
This English version of the path-breaking French book on this subject gives the definitive treatment of the revolutionary approach to measure theory, geometry, and mathematical physics developed by Alain Connes. Profusely illustrated and invitingly written, this book is ideal for anyone who wants to know what noncommutative geometry is, what it can do, or how it can be used in various areas of mathematics, quantization, and elementary particles and fields.Key Features* First full treatment of the subject and its applications* Written by the pioneer of this field* Broad applications in mathemat
Imaging of THz waves in 2D photonic crystal structures embedded in a slab waveguide
International Nuclear Information System (INIS)
Peier, P; Merbold, H; Feurer, T; Pahinin, V; Nelson, K A
2010-01-01
We present space- and time-resolved simulations and measurements of single-cycle terahertz (THz) waves propagating through two-dimensional (2D) photonic crystal structures embedded in a slab waveguide. Specifically, we use a plane wave expansion technique to calculate the band structure and a time-dependent finite-element method to simulate the temporal evolution of the THz waves. Experimentally, we measure the space-time evolution of the THz waves through a coherent time-resolved imaging method. Three different structures are laser machined in LiNbO 3 crystal slabs and analyzing the transmitted as well as the reflected THz waveforms allows determination of the bandgaps. Comparing the results with the calculated band diagrams and the time-dependent simulations shows that the experiments are consistent with 3D simulations, which include the slab waveguide geometry, the birefringence of the material, and a careful analysis of the excited modes within the band diagrams.
Optimization of Cylindrical Hall Thrusters
International Nuclear Information System (INIS)
Raitses, Yevgeny; Smirnov, Artem; Granstedt, Erik; Fisch, Nathaniel J.
2007-01-01
The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation.
Optimization of Cylindrical Hall Thrusters
International Nuclear Information System (INIS)
Raitses, Yevgeny; Smirnov, Artem; Granstedt, Erik; Fi, Nathaniel J.
2007-01-01
The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation
Indentation of Ellipsoidal and Cylindrical Elastic Shells
Vella, Dominic
2012-10-01
Thin shells are found in nature at scales ranging from viruses to hens\\' eggs; the stiffness of such shells is essential for their function. We present the results of numerical simulations and theoretical analyses for the indentation of ellipsoidal and cylindrical elastic shells, considering both pressurized and unpressurized shells. We provide a theoretical foundation for the experimental findings of Lazarus etal. [following paper, Phys. Rev. Lett. 109, 144301 (2012)PRLTAO0031-9007] and for previous work inferring the turgor pressure of bacteria from measurements of their indentation stiffness; we also identify a new regime at large indentation. We show that the indentation stiffness of convex shells is dominated by either the mean or Gaussian curvature of the shell depending on the pressurization and indentation depth. Our results reveal how geometry rules the rigidity of shells. © 2012 American Physical Society.
Sensitivity optimization in whispering gallery mode optical cylindrical biosensors
Khozeymeh, F.; Razaghi, M.
2018-01-01
Whispering-gallery-mode resonances propagated in cylindrical resonators have two angular and radial orders of l and i. In this work, the higher radial order whispering-gallery-mode resonances, (i = 1 - 4), at a fixed l are examined. The sensitivity of theses resonances is analysed as a function of the structural parameters of the cylindrical resonator like different radii and refractive index of composed material of the resonator. A practical application where cylindrical resonators are used for the measurement of glucose concentration in water is presented as a biosensor demonstrator. We calculate the wavelength shifts of the WG1-4, in several glucose/water solutions, with concentrations spanning from 0.0% to 9.0.% (weight/weight). Improved sensitivity can be achieved using multi-WGM cylindrical resonators with radius of R = 100 μm and resonator composed material of MgF 2 with refractive index of nc = 1.38. Also the effect of polarization on sensitivity is considered for all four WGMs. The best sensitivity of 83.07 nm/RIU for the fourth WGM with transverse magnetic polarization, is reported. These results propose optimized parameters aimed to fast designing of cylindrical resonators as optical biosensors, where both the sensitivity and the geometries can be optimized.
Indian Academy of Sciences (India)
mathematicians are trained to use very precise language, and so find it hard to simplify and state .... thing. If you take a plane on which there are two such triangles which enjoy the above ... within this geometry to simplify things if needed.
Geometry -----------~--------------RESONANCE
Indian Academy of Sciences (India)
Parallel: A pair of lines in a plane is said to be parallel if they do not meet. Mathematicians were at war ... Subsequently, Poincare, Klein, Beltrami and others refined non-. Euclidean geometry. ... plane divides the plane into two half planes and.
Cylindrical Three-Dimensional Porous Anodic Alumina Networks
Directory of Open Access Journals (Sweden)
Pedro M. Resende
2016-11-01
Full Text Available The synthesis of a conformal three-dimensional nanostructure based on porous anodic alumina with transversal nanopores on wires is herein presented. The resulting three-dimensional network exhibits the same nanostructure as that obtained on planar geometries, but with a macroscopic cylindrical geometry. The morphological analysis of the nanostructure revealed the effects of the initial defects on the aluminum surface and the mechanical strains on the integrity of the three-dimensional network. The results evidence the feasibility of obtaining 3D porous anodic alumina on non-planar aluminum substrates.
Equipment installation structure of roof slab for tank type FBR and method of equipment installation
International Nuclear Information System (INIS)
Sakai, Takao; Yamakawa, Masanori; Otsuka, Masaya; Sekine, Katsuhisa
1986-01-01
Purpose: To reduce equipment thermal stress and deformation by eliminating uneven temperature distribution caused at the equipment through section of the roof slab for the tank FBR, and at the same time, simplify the structure installation. Method: Multiple number of vertical fin projects are fit on the equipment through-section inside wall for the roof slab and the cylindrical equipment peripheral wall, and with these projected fins, the ring space of the through section is vertically divided into multiple sections in the circumferential direction. The vertical fins on the through-section inside wall and the fins on the equipment peripheral wall are contacted with each other by revolving them in the lateral direction. As a result, the natural convection caused by the difference of temperatures in the vertical direction of the ring space becomes a convection within each sector divided, and never generates circumferential circulation, which reduce uneven temperature distribution caused at the equipment through section. (Kawakami, Y.)
Estimation of the Reliability of Plastic Slabs
DEFF Research Database (Denmark)
Pirzada, G. B. : Ph.D.
In this thesis, work related to fundamental conditions has been extended to non-fundamental or the general case of probabilistic analysis. Finally, using the ss-unzipping technique a door has been opened to system reliability analysis of plastic slabs. An attempt has been made in this thesis...... to give a probabilistic treatment of plastic slabs which is parallel to the deterministic and systematic treatment of plastic slabs by Nielsen (3). The fundamental reason is that in Nielsen (3) the treatment is based on a deterministic modelling of the basic material properties for the reinforced...
Biryol, C. B.; Wagner, L. S.; Fischer, K. M.; Hawman, R. B.
2014-12-01
Our new results from teleseismic, finite-frequency, body-wave tomography analysis reveal a relatively steep east-dipping fast velocity anomaly beneath the Southeastern US. The resolving power of our dataset is good enough to retrieve major mantle anomalies, such as this fast velocity body, owing to the dense receiver coverage provided by US Transportable Array (TA) and the SouthEastern Suture of the Appalachian Margin Experiment (SESAME). Various resolution and recovery tests demonstrate the robustness of this anomaly in our tomographic model between the depths of 60 and 660 km. Our images reveal that the dip of this structure decreases significantly in the mantle transition zone where it terminates. We also observe major gaps in the lateral continuity of this structure. Based on the amplitude, location and geometry of the velocity perturbation, we interpret this anomaly as remnant subducted lithosphere, suspended in the upper mantle after a subduction phase as young as 100-110 Ma or as old as 1Ga. Basic calculations and evaluations on the geometry and location of this anomaly help us to narrow down the origin of this slab to the Farallon flat-slab subduction in the west and Grenville Subduction during assembly of supercontinent Rodinia. Our images reveal possible mechanisms that would allow this slab to remain in the upper mantle without sinking into deeper mantle for such extended periods of time. We believe the flat geometry of the slab near the transition zone and the fragmented nature provide important clues about processes that could delay/resist the sinking while providing necessary time for it to transform into a more neutrally buoyant state. In this respect, we believe our results have broad implications for subduction processes and piece-meal slab failure, as well as tectonic implications for characteristics of former subduction zones that help shape North American Plate.
Analysis of Double Skin Composite Slabs
Directory of Open Access Journals (Sweden)
Husain M. Husain
2018-03-01
Full Text Available This paper deals with finite element modeling of the ultimate load behavior of double skin composite (DSC slabs. In a DSC slab, shear connectors in the form of nut bolt technique studs are used to transfer shear between the outer skin made of steel plates and the concrete core. The current study is based on finite element analysis using ANSYS Version 11 APDL release computer program. Experimental programmes were carried out by the others, two simply supported DSC beams were tested until failure under a concentrated load applied at the center. These test specimens were analyzed by the finite element method and the analyses have shown that these slabs displayed a high degree of flexural characteristics, ultimate strength, and ductility. The close agreement has been observed between the finite element and experimental results for ultimate loads and load–deflection responses. The finite element model was thus found to be capable of predicting the behavior of DSC slabs accurately.
Calculating seismic of slabs ITA NNP Garona
International Nuclear Information System (INIS)
Ezeberry, J. I.; Guerrero, A.; Gamarra, J.; Beltran, F.
2014-01-01
This article describes the methodology that Idom has employed to perform the seismic evaluation of slabs within the ITA project of the NPP Santa Maria de Garona. Seismic calculations that have been conducted include consideration of the effects of the interaction of soil structure as well as the possible take-off containers with respect to slab during the earthquake. Therefore, the main contribution of the work is the study of the coupling of rolling containers with the flexibility of the whole ground-slab For calculations has been used ABAQUS/Explicit program, allowing to solve effectively the nonlinearities listed above using explicit integration algorithms over time. The results of the calculations reflect the importance of jointly analyse the seismic responses of slab and containers. (Author)
Petersen, Peter
2016-01-01
Intended for a one year course, this text serves as a single source, introducing readers to the important techniques and theorems, while also containing enough background on advanced topics to appeal to those students wishing to specialize in Riemannian geometry. This is one of the few Works to combine both the geometric parts of Riemannian geometry and the analytic aspects of the theory. The book will appeal to a readership that have a basic knowledge of standard manifold theory, including tensors, forms, and Lie groups. Important revisions to the third edition include: a substantial addition of unique and enriching exercises scattered throughout the text; inclusion of an increased number of coordinate calculations of connection and curvature; addition of general formulas for curvature on Lie Groups and submersions; integration of variational calculus into the text allowing for an early treatment of the Sphere theorem using a proof by Berger; incorporation of several recent results about manifolds with posit...
International Nuclear Information System (INIS)
Strominger, A.
1990-01-01
A special manifold is an allowed target manifold for the vector multiplets of D=4, N=2 supergravity. These manifolds are of interest for string theory because the moduli spaces of Calabi-Yau threefolds and c=9, (2,2) conformal field theories are special. Previous work has given a local, coordinate-dependent characterization of special geometry. A global description of special geometries is given herein, and their properties are studied. A special manifold M of complex dimension n is characterized by the existence of a holomorphic Sp(2n+2,R)xGL(1,C) vector bundle over M with a nowhere-vanishing holomorphic section Ω. The Kaehler potential on M is the logarithm of the Sp(2n+2,R) invariant norm of Ω. (orig.)
International Nuclear Information System (INIS)
Xu, Xinhua; Yu, Jinghua; Wang, Shengwei; Wang, Jinbo
2014-01-01
conditioning are also critically reviewed, One-dimensional, two-dimensional and three-dimensional models can be found in the literature for successfully simulating these heat transfer process. A finite element or finite difference method is often used for problem solving of two-dimensional or three-dimensional models. These detailed numerical solutions usually require lots of computation demand and limit the practical application in conventional building simulation packages. Simplified thermal network models are simple and easy to be developed, the parameters of these thermal network models were determined manually based on the geometry description of the slab which may deteriorate the modeling accuracy. Simulation-based performance evaluations and in situ measurements show that significant energy and operation cost could be saved, the peak cooling load or heat load can also be reduced significantly when conventional air-conditioning systems are used as supplements. Finally, this review shows that more works on the active slab are worthwhile for further promoting these slabs to be used in low energy architecture for improving energy efficiency and occupant thermal comfort wherever the climate is appropriate
Hrubesova, E.; Lahuta, H.; Mohyla, M.; Quang, T. B.; Phi, N. D.
2018-04-01
The paper is focused on the sensitivity analysis of behaviour of the subsoil – foundation system as regards the variant properties of fibre-concrete slab resulting into different relative stiffness of the whole cooperating system. The character of slab and its properties are very important for the character of external load transfer, but the character of subsoil cannot be neglected either because it determines the stress-strain behaviour of the all system and consequently the bearing capacity of structure. The sensitivity analysis was carried out based on experimental results, which include both the stress values in soil below the foundation structure and settlements of structure, characterized by different quantity of fibres in it. Flat dynamometers GEOKON were used for the stress measurements below the observed slab, the strains inside slab were registered by tensometers, the settlements were monitored geodetically. The paper is focused on the comparison of soil stresses below the slab for different quantity of fibres in structure. The results obtained from the experimental stand can contribute to more objective knowledge of soil – slab interaction, to the evaluation of real carrying capacity of the slab, to the calibration of corresponding numerical models, to the optimization of quantity of fibres in the slab, and finally, to higher safety and more economical design of slab.
Mantle wedge serpentinization effects on slab dips
Directory of Open Access Journals (Sweden)
Eh Tan
2017-01-01
Full Text Available The mechanical coupling between a subducting slab and the overlying mantle wedge is an important factor in controlling the subduction dip angle and the flow in mantel wedge. This paper investigates the role of the amount of mantle serpentinization on the subduction zone evolution. With numerical thermos-mechanical models with elasto-visco-plastic rheology, we vary the thickness and depth extent of mantle serpentinization in the mantle wedge to control the degree of coupling between the slab and mantle wedge. A thin serpentinized mantle layer is required for stable subduction. For models with stable subduction, we find that the slab dip is affected by the down-dip extent and the mantle serpentinization thickness. A critical down-dip extent exists in mantle serpentinization, determined by the thickness of the overriding lithosphere. If the down-dip extent does not exceed the critical depth, the slab is partially coupled to the overriding lithosphere and has a constant dip angle regardless of the mantle serpentinization thickness. However, if the down-dip extent exceeds the critical depth, the slab and the base of the overriding lithosphere would be separated and decoupled by a thick layer of serpentinized peridotite. This allows further slab bending and results in steeper slab dip. Increasing mantle serpentinization thickness will also result in larger slab dip. We also find that with weak mantle wedge, there is no material flowing from the asthenosphere into the serpentinized mantle wedge. All of these results indicate that serpentinization is an important ingredient when studying the subduction dynamics in the mantle wedge.
Imaging subducted slabs using seismic arrays in the Western Pacific
Bentham, H. L.; Rost, S.
2010-12-01
In recent years array seismology has been used extensively to image the small scale structure of the Earth. Such structure likely represents chemical heterogeneity and is therefore essential in our understanding of mantle convection and the composition of the Earth’s deep interior. As subduction is the main source of (re)introducing slab material into the Earth, it is of particular interest to track these heterogeneities. Resolving details of the composition and deformation of subducted lithosphere can help provide constraints on the subduction process, the composition of the mantle and mantle convection. This study uses seismic array techniques to map seismic heterogeneities associated with western Pacfic subduction zones, where a variety of slab geometries have been previously observed. Seismic energy arriving prior to the PP arrival was analysed at Eielson Array (ILAR), Alaska. More than 200 earthquakes were selected with Mw ≥ 6 and with epicentral distances of 90-110deg, giving a good coverage of the PP precursor (P*P) wavefield. Initial findings indicate that the observed P*P arrive out of plane and are likely a result of scattering. These scatterers are linked to the subduction of the Pacific Plate under the Philippine Sea in the Izu-Bonin and Mariana subduction zones. To enable efficient processing of large datasets, a robust automatic coherent (but unpredicted) arrival detector algorithm has been developed to select suitable precursors. Slowness and backazimuth were calculated for each precursor and were used in conjunction with P*P arrival times to back-raytrace the energy from the array to the scatterer location. Processing of the full dataset will help refine models regarding slab deformation as they descend into the mantle as well as unveiling the depth of their descent.
International Nuclear Information System (INIS)
Albertazzi, Armando Jr; Pont, Alex Dal
2005-01-01
This paper introduces a new design of a white light interferometer, suitable for measurement of cylindrical or quasi-cylindrical parts. A high precision 45 deg. conical mirror is used to direct collimated light radially, making it possible to measure in true cylindrical coordinates. The image of the measurand, distorted by the conical mirror, is projected in a high resolution digital camera. A mapping algorithm is used to reconstruct the cylindrical geometry from the distorted image. The rest of the interferometer is quite similar to a conventional white light interferometer: A flat reference mirror is scanned through the measurement range while an algorithm is searching for the maximum contrast position of the interference pattern. The performance evaluation of a configuration suitable for measurement of external cylindrical surfaces is also presented in this paper. A master cylinder was used as reference. Uncertainties of about 1.0 μm were found at the present stage of development
General Geometry and Geometry of Electromagnetism
Shahverdiyev, Shervgi S.
2002-01-01
It is shown that Electromagnetism creates geometry different from Riemannian geometry. General geometry including Riemannian geometry as a special case is constructed. It is proven that the most simplest special case of General Geometry is geometry underlying Electromagnetism. Action for electromagnetic field and Maxwell equations are derived from curvature function of geometry underlying Electromagnetism. And it is shown that equation of motion for a particle interacting with electromagnetic...
Analytical SN solutions in heterogeneous slabs using symbolic algebra computer programs
International Nuclear Information System (INIS)
Warsa, J.S.
2002-01-01
A modern symbolic algebra computer program, MAPLE, is used to compute solutions to the well-known analytical discrete ordinates, or S N , solutions in one-dimensional, slab geometry. Symbolic algebra programs compute the solutions with arbitrary precision and are free of spatial discretization error so they can be used to investigate new discretizations for one-dimensional slab, geometry S N methods. Pointwise scalar flux solutions are computed for several sample calculations of interest. Sample MAPLE command scripts are provided to illustrate how easily the theory can be translated into a working solution and serve as a complete tool capable of computing analytical S N solutions for mono-energetic, one-dimensional transport problems
Energy Technology Data Exchange (ETDEWEB)
Molbert, M; Sauve, A; Houelle, M; Deilgat, E [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1964-07-01
The criticality station of Dijon involves three cells, shielded by concrete walls of 1.46 meter thickness. Those cells are designed to contain the criticality experiment apparatus. The engineering building is also involving: one chemical laboratory where plutonium solutions are prepared, one analysis laboratory, several activated solutions storages, several control rooms, One cell contains the B system, which is designed to study: annular cylindrical geometries, slab of 10 cm thickness, interaction between annular cylinders. This report includes the first results given by experiments on annular cylinders defined by their own geometry (outer and inner diameter of ring containing plutonium solutions). Those results have been plotted in curves, for several concentrations and for different reflection conditions (outer or inner light water reflector, cadmium screen), H{sub c} and M{sub c} = f (c) (where H{sub c} is the critical height of solution, M{sub c} is the critical mass, c is the plutonium concentration: 42,3 g/l
Influence of slab connection in case of expanded concrete pavements
Deluka-Tibljaš, Aleksandra; Prager, Andrija; Rukavina, Tatjana
2002-01-01
Load transfer from the stressed slab to the neighboring unstressed slab is analyzed in order to establish possibilities for stress reduction in concrete. The contact between slabs is established by means of reinforcing steel shear studs while the influence of friction in the concrete to concrete contact is neglected. The influence of slab thickness, slab cross-section and spacing of shear studs is analyzed, and the expansion joint movement due to change in temperature is studied. Conditions e...
Cylindrical acoustic levitator/concentrator
Kaduchak, Gregory; Sinha, Dipen N.
2002-01-01
A low-power, inexpensive acoustic apparatus for levitation and/or concentration of aerosols and small liquid/solid samples having particulates up to several millimeters in diameter in air or other fluids is described. It is constructed from a commercially available, hollow cylindrical piezoelectric crystal which has been modified to tune the resonance frequency of the breathing mode resonance of the crystal to that of the interior cavity of the cylinder. When the resonance frequency of the interior cylindrical cavity is matched to the breathing mode resonance of the cylindrical piezoelectric transducer, the acoustic efficiency for establishing a standing wave pattern in the cavity is high. The cylinder does not require accurate alignment of a resonant cavity. Water droplets having diameters greater than 1 mm have been levitated against the force of gravity using; less than 1 W of input electrical power. Concentration of aerosol particles in air is also demonstrated.
Detonation Propagation in Slabs and Axisymmetric Rate Sticks
Romick, Christopher; Aslam, Tariq
Insensitive high explosives (IHE) have many benefits; however, these IHEs exhibit longer reaction zones than more conventional high explosives (HE). This makes IHEs less ideal explosives and more susceptible to edge effects as well as other performance degradation issues. Thus, there is a resulting reduction in the detonation speed within the explosive. Many HE computational models, e. g. WSD, SURF, CREST, have shock-dependent reaction rates. This dependency places a high value on having an accurate shock speed. In the common practice of shock-capturing, there is ambiguity in the shock-state due to smoothing of the shock-front. Moreover, obtaining an accurate shock speed with shock-capturing becomes prohibitively computationally expensive in multiple dimensions. The use of shock-fitting removes the ambiguity of the shock-state as it is one of the boundaries. As such, the required resolution for a given error in the detonation speed is less than with shock-capturing. This allows for further insight into performance degradation. A two-dimensional shock-fitting scheme has been developed for unconfined slabs and rate sticks of HE. The HE modeling is accomplished by Euler equations utilizing several models with single-step irreversible kinetics in slab and rate stick geometries. Department of Energy - LANL.
Efficient diode-side-pumped Nd:YVO4 slab laser in different generation regimes
International Nuclear Information System (INIS)
Zinov'ev, A P; Antipov, Oleg L; Novikov, A A
2009-01-01
A diode-side-pumped Nd:YVO 4 slab laser with the grazing-incidence bounce geometry of the cavity is studied experimentally. Upon continuous pumping different lasing regimes are realised, namely, cw, passive and active Q-switching and passive mode-locking. The resonator parameters are optimised to achieve the maximum cw output power (∼17 W) and high-quality beam (M 2 ∼ 1.3). (lasers)
Ciarlet, Philippe G
2007-01-01
This book gives the basic notions of differential geometry, such as the metric tensor, the Riemann curvature tensor, the fundamental forms of a surface, covariant derivatives, and the fundamental theorem of surface theory in a selfcontained and accessible manner. Although the field is often considered a classical one, it has recently been rejuvenated, thanks to the manifold applications where it plays an essential role. The book presents some important applications to shells, such as the theory of linearly and nonlinearly elastic shells, the implementation of numerical methods for shells, and
Bernal-Olaya, R.; Mann, P.; Vargas, C. A.; Koulakov, I.
2013-12-01
We define the length and geometry of eastward and southeastward-subducting slabs beneath northwestern South America in Colombia using ~100,000 earthquake events recorded by the Colombian National Seismic Network from 1993 to 2012. Methods include: hypocenter relocation, compilation of focal mechanisms, and P and S wave tomographic calculations performed using LOTOS and Seisan. The margins of Colombia include four distinct subduction zones based on slab dip: 1) in northern Colombia, 12-16-km-thick oceanic crust subducts at a modern GPS rate of 20 mm/yr in a direction of 110 degrees at a shallow angle of 8 degrees; as a result of its low dip, Pliocene-Pleistocene volcanic rocks are present 400 km from the frontal thrust; magmatic arc migration to the east records 800 km of subduction since 58 Ma ago (Paleocene) with shallow subduction of the Caribbean oceanic plateau starting ~24-33 Ma (Miocene); at depths of 90-150 km, the slab exhibits a negative velocity anomaly we associate with pervasive fracturing; 2) in the central Colombia-Panama area, we define an area of 30-km-thick crust of the Panama arc colliding/subducting at a modern 30/mm in a direction of 95 degrees; the length of this slab shows subduction/collision initiated after 20 Ma (Middle Miocene); we call this feature the Panama indenter since it has produced a V-shaped indentation of the Colombian margin and responsible for widespread crustal deformation and topographic uplift in Colombia; an incipient subduction area is forming near the Panama border with intermediate earthquakes at an eastward dip of 70 degrees to depths of ~150 km; this zone is not visible on tomographic images; 3) a 250-km-wide zone of Miocene oceanic crust of the Nazca plate flanking the Panama indenter subducts at a rate of 25 mm/yr in a direction of 55 degrees and at a normal dip of 40 degrees; the length of this slab suggests subduction began at ~5 Ma; 4) the Caldas tear defines a major dip change to the south where a 35 degrees
Telescoping cylindrical piezoelectric fiber composite actuator assemblies
Allison, Sidney G. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, legal representative, Christopher L. (Inventor); Fox Chattin, legal representative, Melanie L. (Inventor)
2010-01-01
A telescoping actuator assembly includes a plurality of cylindrical actuators in a concentric arrangement. Each cylindrical actuator is at least one piezoelectric fiber composite actuator having a plurality of piezoelectric fibers extending parallel to one another and to the concentric arrangement's longitudinal axis. Each cylindrical actuator is coupled to concentrically-adjacent ones of the cylindrical actuators such that the plurality of cylindrical actuators can experience telescopic movement. An electrical energy source coupled to the cylindrical actuators applies actuation energy thereto to generate the telescopic movement.
Filling of charged cylindrical capillaries
Das, Siddhartha; Chanda, Sourayon; Eijkel, J.C.T.; Tas, N.R.; Chakraborty, Suman; Mitra, Sushanta K.
2014-01-01
We provide an analytical model to describe the filling dynamics of horizontal cylindrical capillaries having charged walls. The presence of surface charge leads to two distinct effects: It leads to a retarding electrical force on the liquid column and also causes a reduced viscous drag force because
Optics Demonstrations Using Cylindrical Lenses
Ivanov, Dragia; Nikolov, Stefan
2015-01-01
In this paper we consider the main properties of cylindrical lenses and propose several demonstrational experiments that can be performed with them. Specifically we use simple glasses full of water to demonstrate some basic geometrical optics principles and phenomena. We also present some less standard experiments that can be performed with such…
Dismantling OPAL's cylindrical magnet core
Laurent Guiraud
2001-01-01
Lifting a handling device for dismounting the pressure bells, which are inside the cylindrical magnet coil on the central section of OPAL, on the right part of the photo. OPAL was a detector on the LEP accelerator, which ran from 1989 to 2000.
Cylindrical thin-shell wormholes
International Nuclear Information System (INIS)
Eiroa, Ernesto F.; Simeone, Claudio
2004-01-01
A general formalism for the dynamics of nonrotating cylindrical thin-shell wormholes is developed. The time evolution of the throat is explicitly obtained for thin-shell wormholes whose metric has the form associated with local cosmic strings. It is found that the throat collapses to zero radius, remains static, or expands forever, depending only on the sign of its initial velocity
Accidents due to falls from roof slabs.
Rudelli, Bruno Alves; Silva, Marcelo Valerio Alabarce da; Akkari, Miguel; Santili, Claudio
2013-01-01
CONTEXT AND OBJECTIVE Falls from the roof slabs of houses are accidents of high potential severity that occur in large Brazilian cities and often affect children and adolescents. The aims of this study were to characterize the factors that predispose towards this type of fall involving children and adolescents, quantify the severity of associated lesions and suggest preventive measures. DESIGN AND SETTING Descriptive observational prospective longitudinal study in two hospitals in the metropolitan region of São Paulo. METHODS Data were collected from 29 cases of falls from roof slabs involving children and adolescents between October 2008 and October 2009. RESULTS Cases involving males were more prevalent, accounting for 84%. The predominant age group was schoolchildren (7 to 12 years old; 44%). Leisure activities were most frequently being practiced on the roof slab at the time of the fall (86%), and flying a kite was the most prevalent game (37.9%). In 72% of the cases, the children were unaccompanied by an adult responsible for them. Severe conditions such as multiple trauma and traumatic brain injuries resulted from 79% of the accidents. CONCLUSION Falls from roof slabs are accidents of high potential severity, and preventive measures aimed towards informing parents and guardians about the dangers and risk factors associated with this type of accident are needed, along with physical protective measures, such as low walls around the slab and gates with locks to restrict free access to these places.
Accidents due to falls from roof slabs
Directory of Open Access Journals (Sweden)
Bruno Alves Rudelli
Full Text Available CONTEXT AND OBJECTIVE Falls from the roof slabs of houses are accidents of high potential severity that occur in large Brazilian cities and often affect children and adolescents. The aims of this study were to characterize the factors that predispose towards this type of fall involving children and adolescents, quantify the severity of associated lesions and suggest preventive measures. DESIGN AND SETTING Descriptive observational prospective longitudinal study in two hospitals in the metropolitan region of São Paulo. METHODS Data were collected from 29 cases of falls from roof slabs involving children and adolescents between October 2008 and October 2009. RESULTS Cases involving males were more prevalent, accounting for 84%. The predominant age group was schoolchildren (7 to 12 years old; 44%. Leisure activities were most frequently being practiced on the roof slab at the time of the fall (86%, and flying a kite was the most prevalent game (37.9%. In 72% of the cases, the children were unaccompanied by an adult responsible for them. Severe conditions such as multiple trauma and traumatic brain injuries resulted from 79% of the accidents. CONCLUSION Falls from roof slabs are accidents of high potential severity, and preventive measures aimed towards informing parents and guardians about the dangers and risk factors associated with this type of accident are needed, along with physical protective measures, such as low walls around the slab and gates with locks to restrict free access to these places.
Subducted slabs and lateral viscosity variations: effects on the long-wavelength geoid
Tosi, Nicola; Čadek, Ondřej; Martinec, Zdeněk
2009-11-01
The characteristic broad local maxima exhibited by the long-wavelength geoid over subduction zones are investigated with a numerical model of mantle flow. In a spherical axisymmetric geometry, a synthetic model of buoyancy driven subduction is used to test the effects on the geoid caused by the depth of penetration of the lithosphere into the mantle, by the viscosity stratification and by lateral viscosity variations (LVV) in the lithosphere, upper and lower mantle. The presence of anomalous slab density in the lower mantle guarantees geoid amplitudes comparable with the observations, favouring the picture of slabs that penetrate the transition zone and sink into the deep mantle. The viscosity of the lower mantle controls the long-wavelength geoid to the first order, ensuring a clear positive signal when it is at least 30-times greater than the upper-mantle viscosity. The presence of LVV in the lithosphere, in the form of weak plate margins, helps to increase the contribution of the surface topography, causing a pronounced reduction of the geoid. Localized LVV associated with the cold slab play a secondary role if they are in the upper mantle. On the other hand, highly viscous slabs in the lower mantle exert a large influence on the geoid. They cause its amplitude to increase dramatically, way beyond the values typically observed over subduction zones. Long-wavelength flow becomes less vigorous as the slab viscosity increases. Deformation in the upper mantle becomes more localized and power is transferred to short wavelengths, causing the long-wavelength surface topography to diminish and the total geoid to increase. Slabs may be then weakened in the lower mantle or retain their high viscosity while other mechanisms act to lower the geoid. It is shown that a phase change from perovskite to post-perovskite above the core-mantle boundary can cause the geoid to reduce significantly, thereby helping to reconcile models and observations.
Horton, B. K.; Fuentes, F.; McKenzie, N. R.; Constenius, K. N.; Alvarado, P. M.
2014-12-01
Debate persists over the effects of flat-slab subduction on the kinematics of overriding plate deformation and the evolution of retroarc sedimentary basins. In western Argentina, major spatial and temporal variations in the geometry of the subducting Nazca slab since ~15 Ma provide opportunities to evaluate the late Cenozoic response of the Andean fold-thrust belt and foreland basin to subhorizontal subduction. Preliminary results from several structural and sedimentary transects spanning the frontal thrust belt and foreland basin system between 31°S and 35°S reveal Oligocene-middle Miocene hinterland exhumation during normal-slab subduction followed thereafter by progressive slab shallowing with initial rapid cratonward propagation of ramp-flat thrust structures (prior to basement-involved foreland uplifts) and accompanying wholesale exhumation and recycling of the early Andean foreland basin (rather than regional dynamic subsidence). Detrital zircon U-Pb geochronologic data prove instrumental for revealing shifts in thrust-belt exhumation, defining depositional ages within the foreland basin, and constraining the timing of activity along frontal thrust structures. In both the San Juan (31-32°S) and Malargüe (34-35°S) segments of the fold-thrust belt, geochronological results for volcaniclastic sandstones and syndeformational growth strata are consistent with a major eastward advance in shortening at 12-9 Ma. This episode of rapid thrust propagation precedes the reported timing of Sierras Pampeanas basement-involved foreland uplifts and encompasses modern regions of both normal- and flat-slab subduction, suggesting that processes other than slab dip (such as inherited crustal architecture, critical wedge dynamics, and arc magmatism) are additional regulators of thrust-belt kinematics and foreland basin evolution.
Slab tears and intermediate-depth seismicity
Meighan, Hallie E.; ten Brink, Uri S.; Pulliam, Jay
2013-01-01
Active tectonic regions where plate boundaries transition from subduction to strike slip can take several forms, such as triple junctions, acute, and obtuse corners. Well-documented slab tears that are associated with high rates of intermediate-depth seismicity are considered here: Gibraltar arc, the southern and northern ends of the Lesser Antilles arc, and the northern end of Tonga trench. Seismicity at each of these locations occurs, at times, in the form of swarms or clusters, and various authors have proposed that each marks an active locus of tear propagation. The swarms and clusters start at the top of the slab below the asthenospheric wedge and extend 30–60 km vertically downward within the slab. We propose that these swarms and clusters are generated by fluid-related embrittlement of mantle rocks. Focal mechanisms of these swarms generally fit the shear motion that is thought to be associated with the tearing process.
Behaviour of a stiffened circular slab
International Nuclear Information System (INIS)
Kulkarni, M.G.; Subramanian, K.V.
1975-01-01
Configuration of intake structure for cooling water system for Madras Atomic Power Project was studied on a hydraulic model and it was recommended to provide a circular slab in the structure to give directional property to the inflow and reduce air entrainment. This slab, as indicated by hydraulic model tests was required to withstand hydrodynamic pressures of the order of 10T/m 2 due to breaking waves of about 6 m height. Analysis of this circular cover slab, Stiffened by radial and circumferential beams, carried with the help of an analysis based on grid idealisation is presented. Results of approximate design analysis to assess behaviour of radial stiffener have been compared. Actual design is based on judgement of actual degree of fixity possessed by the supports or restraints. (author)
Fire resistance of prefabricated monolithic slab
Directory of Open Access Journals (Sweden)
Gravit Marina
2017-01-01
Full Text Available A prefabricated monolithic slab (PMS has a number of valuable advantages, they allow to significantly decrease the weight of construction keeping the necessary structural-load capacity, to speed up and cheapen work conduction, to increase the heat isolating properties of an enclosure structure [1]. In order to create a design method of prefabricated monolithic slab fire-resistance, it's necessary to perform a series of PMS testing, one of which is being described in this article. Subjected to the test is a fragment of prefabricated monolithic slab with polystyrene concrete inserts along the beams with bent metal profile 250 mm thick, with a 2.7 m span loaded with evenly spread load equal to 600 kg/m2. After 3 hour testing for fire-resistance [2] no signs of construction ultimate behavior were detected.
Homotheties of cylindrically symmetric static spacetimes
International Nuclear Information System (INIS)
Qadir, A.; Ziad, M.; Sharif, M.
1998-08-01
In this note we consider the homotheties of cylindrically symmetric static spacetimes. We find that we can provide a complete list of all metrics that admit non-trivial homothetic motions and are cylindrically symmetric static. (author)
Directory of Open Access Journals (Sweden)
Qing-yuan Xu
Full Text Available A subway train-steel spring floating slab track-tunnel coupling dynamic model, considering short and middle-long wavelength random track irregularities, and longitudinal connection between adjacent slabs of steel spring floating slab track, was developed. And the influence of slab length on dynamic characteristics of the system under different track conditions and train speeds are theoretically studied. The calculated results show: (1 In general, the acceleration of each component of the coupled system decreases with the increase of slab length under the perfectly smooth track condition; (2 Slab length has different influence laws on acceleration of each component of subway train-steel spring floating slab track-tunnel coupled system under random irregularity of track condition. The lower the dominant frequency distribution of vibration acceleration is, the higher influence slab length has; (3 With the increase of slab length, the force of rail, fastener and steel spring also decreases significantly, which helps to lengthen the service life of these components; (4 With the increase of slab length, the longitudinal bending moment of slab increases sharply at first, then it begins to drop slightly. When slab length exceeds the distance between two bogies of a vehicle, the longitudinal bending moment of slab changes little; (5 Slab length has significant influence on the dynamic force and displacement of the coupled system when train speed is higher.
Cylindrization of a PWR core for neutronic calculations
International Nuclear Information System (INIS)
Santos, Rubens Souza dos
2005-01-01
In this work we propose a core cylindrization, starting from a PWR core configuration, through the use of an algorithm that becomes the process automated in the program, independent of the discretization. This approach overcomes the problem stemmed from the use of the neutron transport theory on the core boundary, in addition with the singularities associated with the presence of corners on the outer fuel element core of, existents in the light water reactors (LWR). The algorithm was implemented in a computational program used to identification of the control rod drop accident in a typical PWR core. The results showed that the algorithm presented consistent results comparing with an production code, for a problem with uniform properties. In our conclusions, we suggest, for future works, for analyzing the effect on mesh sizes for the Cylindrical geometry, and to compare the transport theory calculations versus diffusion theory, for the boundary conditions with corners, for typical PWR cores. (author)
Active isotropic slabs: conditions for amplified reflection
Perez, Liliana I.; Matteo, Claudia L.; Etcheverry, Javier; Duplaá, María Celeste
2012-12-01
We analyse in detail the necessary conditions to obtain amplified reflection (AR) in isotropic interfaces when a plane wave propagates from a transparent medium towards an active one. First, we demonstrate analytically that AR is not possible if a single interface is involved. Then, we study the conditions for AR in a very simple configuration: normal incidence on an active slab immersed in transparent media. Finally, we develop an analysis in the complex plane in order to establish a geometrical method that not only describes the behaviour of active slabs but also helps to simplify the calculus.
Active isotropic slabs: conditions for amplified reflection
International Nuclear Information System (INIS)
Perez, Liliana I; Duplaá, María Celeste; Matteo, Claudia L; Etcheverry, Javier
2012-01-01
We analyse in detail the necessary conditions to obtain amplified reflection (AR) in isotropic interfaces when a plane wave propagates from a transparent medium towards an active one. First, we demonstrate analytically that AR is not possible if a single interface is involved. Then, we study the conditions for AR in a very simple configuration: normal incidence on an active slab immersed in transparent media. Finally, we develop an analysis in the complex plane in order to establish a geometrical method that not only describes the behaviour of active slabs but also helps to simplify the calculus. (paper)
Moisture transfer in a concrete slab
International Nuclear Information System (INIS)
Huang, C.L.D.; Siang, H.H.; Kirmser, P.G.
1979-01-01
A diffusion theory with a linear or a nonlinear coefficient of diffusivity is insufficient for the characterization of the drying behaviour of hydrated concrete slabs. A general mathematical model, based on nonequilibrium, irreversible flows of heat and mass, yields a set of nonlinear partial differential equations of parabolic type. Implicit finite difference calculations for a concrete slab yield moisture, temperature, and pressure histories as well as global average drying rates. Graphs show that during the pendular state of dessication, diffusion, capillary, and evaporation-condensation processes are the governing mechanisms in drying. (orig.)
Behaviour of reinforced concrete slabs with steel fibers
Baarimah, A. O.; Syed Mohsin, S. M.
2017-11-01
This paper investigates the potential effect of steel fiber added into reinforced concrete slabs. Four-point bending test is conducted on six slabs to investigate the structural behaviour of the slabs by considering two different parameters; (i) thickness of slab (ii) volume fraction of steel fiber. The experimental work consists of six slabs, in which three slabs are designed in accordance to Eurocode 2 to fulfil shear capacity characteristic, whereas, the other three slabs are designed with 17% less thickness, intended to fail in shear. Both series of slabs are added with steel fiber with a volume fraction of Vf = 0%, Vf = 1% and Vf = 2% in order to study the effect and potential of fiber to compensate the loss in shear capacity. The slab with Vf = 0% steel fiber and no reduction in thickness is taken as the control slab. The experimental result suggests promising improvement of the load carrying capacity (up to 32%) and ductility (up to 87%) as well as delayed in crack propagation for the slabs with Vf = 2%. In addition, it is observed that addition of fibers compensates the reduction in the slab thickness as well as changes the failure mode of the slab from brittle to a more ductile manner.
Density and geometry of single component plasmas
International Nuclear Information System (INIS)
Speck, A.; Gabrielse, G.; Larochelle, P.; Le Sage, D.; Levitt, B.; Kolthammer, W.S.; McConnell, R.; Wrubel, J.; Grzonka, D.; Oelert, W.; Sefzick, T.; Zhang, Z.; Comeau, D.; George, M.C.; Hessels, E.A.; Storry, C.H.; Weel, M.; Walz, J.
2007-01-01
The density and geometry of p-bar and e + plasmas in realistic trapping potentials are required to understand and optimize antihydrogen (H-bar) formation. An aperture method and a quadrupole oscillation frequency method for characterizing such plasmas are compared for the first time, using electrons in a cylindrical Penning trap. Both methods are used in a way that makes it unnecessary to assume that the plasmas are spheroidal, and it is shown that they are not. Good agreement between the two methods illustrates the possibility to accurately determine plasma densities and geometries within non-idealized, realistic trapping potentials
Density and geometry of single component plasmas
Speck, A; Larochelle, P; Le Sage, D; Levitt, B; Kolthammer, W S; McConnell, R; Wrubel, J; Grzonka, D; Oelert, W; Sefzick, T; Zhang, Z; Comeau, D; George, M C; Hessels, E A; Storry, C H; Weel, M; Walz, J
2007-01-01
The density and geometry of p¯ and e+ plasmas in realistic trapping potentials are required to understand and optimize antihydrogen (H¯) formation. An aperture method and a quadrupole oscillation frequency method for characterizing such plasmas are compared for the first time, using electrons in a cylindrical Penning trap. Both methods are used in a way that makes it unnecessary to assume that the plasmas are spheroidal, and it is shown that they are not. Good agreement between the two methods illustrates the possibility to accurately determine plasma densities and geometries within non-idealized, realistic trapping potentials.
Thin shells joining local cosmic string geometries
Energy Technology Data Exchange (ETDEWEB)
Eiroa, Ernesto F. [Universidad de Buenos Aires, Ciudad Universitaria Pabellon I, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Instituto de Astronomia y Fisica del Espacio (IAFE, CONICET-UBA), Buenos Aires (Argentina); Rubin de Celis, Emilio; Simeone, Claudio [Universidad de Buenos Aires, Ciudad Universitaria Pabellon I, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Ciudad Universitaria Pabellon I, IFIBA-CONICET, Buenos Aires (Argentina)
2016-10-15
In this article we present a theoretical construction of spacetimes with a thin shell that joins two different local cosmic string geometries. We study two types of global manifolds, one representing spacetimes with a thin shell surrounding a cosmic string or an empty region with Minkowski metric, and the other corresponding to wormholes which are not symmetric across the throat located at the shell. We analyze the stability of the static configurations under perturbations preserving the cylindrical symmetry. For both types of geometries we find that the static configurations can be stable for suitable values of the parameters. (orig.)
Thin shells joining local cosmic string geometries
International Nuclear Information System (INIS)
Eiroa, Ernesto F.; Rubin de Celis, Emilio; Simeone, Claudio
2016-01-01
In this article we present a theoretical construction of spacetimes with a thin shell that joins two different local cosmic string geometries. We study two types of global manifolds, one representing spacetimes with a thin shell surrounding a cosmic string or an empty region with Minkowski metric, and the other corresponding to wormholes which are not symmetric across the throat located at the shell. We analyze the stability of the static configurations under perturbations preserving the cylindrical symmetry. For both types of geometries we find that the static configurations can be stable for suitable values of the parameters. (orig.)
A new look at the fetus: Thick-slab T2-weighted sequences in fetal MRI
International Nuclear Information System (INIS)
Brugger, Peter C.; Mittermayer, Christoph; Prayer, Daniela
2006-01-01
Although magnetic resonance imaging (MRI) of the fetus is considered an established adjunct to fetal ultrasound, stacks of images alone cannot provide an overall impression of the fetus. The present study evaluates the use of thick-slab T2-weighted MR images to obtain a three-dimensional impression of the fetus using MRI. A thick-slab T2-weighted sequence was added to the routine protocol in 100 fetal MRIs obtained for various indications (19th to 37th gestational weeks) on a 1.5 T magnet using a five-element phased-array surface coil. Slice thickness adapted to fetal size and uterine geometry varied between 25 and 50 mm, as did the field of view (250-350 mm). Acquisition of one image took less than 1 s. The pictorial essay shows that these images visualize fetal anatomy in a more comprehensive way than is possible with a series of 3-4 mm thick slices. These thick-slab images facilitate the assessment of the whole fetus, fetal proportions, surface structures, and extremities. Fetal pathology may be captured in one image. Thick-slab T2-weighted images provide additional information that cannot be gathered from a series of images and are considered a valuable adjunct to conventional 2D MR images
A new look at the fetus: Thick-slab T2-weighted sequences in fetal MRI
Energy Technology Data Exchange (ETDEWEB)
Brugger, Peter C. [Center of Anatomy and Cell Biology, Integrative Morphology Group, Medical University of Vienna, Vienna (Austria)]. E-mail: peter.brugger@meduniwien.ac.at; Mittermayer, Christoph [Department of Neonatology and Intensive Care, University Hospital of Vienna (Austria); Prayer, Daniela [Department of Neuroradiology, University Clinics of Radiodiagnostics, Medical University of Vienna, Vienna (Austria)
2006-02-15
Although magnetic resonance imaging (MRI) of the fetus is considered an established adjunct to fetal ultrasound, stacks of images alone cannot provide an overall impression of the fetus. The present study evaluates the use of thick-slab T2-weighted MR images to obtain a three-dimensional impression of the fetus using MRI. A thick-slab T2-weighted sequence was added to the routine protocol in 100 fetal MRIs obtained for various indications (19th to 37th gestational weeks) on a 1.5 T magnet using a five-element phased-array surface coil. Slice thickness adapted to fetal size and uterine geometry varied between 25 and 50 mm, as did the field of view (250-350 mm). Acquisition of one image took less than 1 s. The pictorial essay shows that these images visualize fetal anatomy in a more comprehensive way than is possible with a series of 3-4 mm thick slices. These thick-slab images facilitate the assessment of the whole fetus, fetal proportions, surface structures, and extremities. Fetal pathology may be captured in one image. Thick-slab T2-weighted images provide additional information that cannot be gathered from a series of images and are considered a valuable adjunct to conventional 2D MR images.
Cross-field flow and electric potential in a plasma slab
Directory of Open Access Journals (Sweden)
J. De Keyser
2013-08-01
Full Text Available We consider cross-field plasma flow inside a field-aligned plasma slab embedded in a uniform background in a 1-dimensional geometry. This situation may arise, for instance, when long-lasting reconnection pulses inject plasma into the inner magnetosphere. The present paper presents a detailed analysis of the structure of the interfaces that separate the slab from the background plasma on either side; a fully kinetic model is used to do so. Since the velocity shear across both interfaces has opposite signs, and given the typical gyroradius differences between injected and background ions and electrons, the structure of both interfaces can be very different. The behaviour of the slab and its interfaces depends critically on the flow of the plasma transverse to the magnetic field; in particular, it is shown that there are bounds to the flow speed that can be supported by the magnetised plasma. Further complicating the picture is the effect of the potential difference between the slab and its environment.
Cylindrical collapse and gravitational waves
Energy Technology Data Exchange (ETDEWEB)
Herrera, L [Escuela de FIsica, Faculdad de Ciencias, Universidad Central de Venezuela, Caracas, Venezuela (Venezuela); Santos, N O [Universite Pierre et Marie Curie, CNRS/FRE 2460 LERMA/ERGA, Tour 22-12, 4eme etage, BoIte 142, 4 place Jussieu, 75252 Paris Cedex 05 (France); Laboratorio Nacional de Computacao Cientifica, 25651-070 Petropolis RJ (Brazil); Centro Brasileiro de Pesquisas Fisicas, 22290-180 Rio de Janeiro RJ (Brazil)
2005-06-21
We study the matching conditions for a collapsing anisotropic cylindrical perfect fluid, and we show that its radial pressure is non-zero on the surface of the cylinder and proportional to the time-dependent part of the field produced by the collapsing fluid. This result resembles the one that arises for the radiation-though non-gravitational-in the spherically symmetric collapsing dissipative fluid, in the diffusion approximation.
Cracking of anisotropic cylindrical polytropes
Energy Technology Data Exchange (ETDEWEB)
Mardan, S.A. [University of the Management and Technology, Department of Mathematics, Lahore (Pakistan); Azam, M. [University of Education, Division of Science and Technology, Lahore (Pakistan)
2017-06-15
We study the appearance of cracking in charged anisotropic cylindrical polytropes with generalized polytropic equation. We investigate the existence of cracking in two different kinds of polytropes existing in the literature through two different assumptions: (a) local density perturbation with conformally flat condition, and (b) perturbing polytropic index, charge and anisotropy parameters. We conclude that cracking appears in both kinds of polytropes for a specific range of density and model parameters. (orig.)
Cylindrical Piezoelectric Fiber Composite Actuators
Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.
2008-01-01
The use of piezoelectric devices has become widespread since Pierre and Jacques Curie discovered the piezoelectric effect in 1880. Examples of current applications of piezoelectric devices include ultrasonic transducers, micro-positioning devices, buzzers, strain sensors, and clocks. The invention of such lightweight, relatively inexpensive piezoceramic-fiber-composite actuators as macro fiber composite (MFC) actuators has made it possible to obtain strains and displacements greater than those that could be generated by prior actuators based on monolithic piezoceramic sheet materials. MFC actuators are flat, flexible actuators designed for bonding to structures to apply or detect strains. Bonding multiple layers of MFC actuators together could increase force capability, but not strain or displacement capability. Cylindrical piezoelectric fiber composite (CPFC) actuators have been invented as alternatives to MFC actuators for applications in which greater forces and/or strains or displacements may be required. In essence, a CPFC actuator is an MFC or other piezoceramic fiber composite actuator fabricated in a cylindrical instead of its conventional flat shape. Cylindrical is used here in the general sense, encompassing shapes that can have circular, elliptical, rectangular or other cross-sectional shapes in the planes perpendicular to their longitudinal axes.
Plastic buckling of cylindrical shells
International Nuclear Information System (INIS)
Bandyopadhyay, K.; Xu, J.; Shteyngart, S.; Eckert, H.
1994-01-01
Cylindrical shells exhibit buckling under axial loads at stresses much less than the respective theoretical critical stresses. This is due primarily to the presence of geometrical imperfections even though such imperfections could be very small (e.g., comparable to thickness). Under internal pressure, the shell regains some of its buckling strength. For a relatively large radius-to-thickness ratio and low internal pressure, the effect can be reasonably estimated by an elastic analysis. However, for low radius-to-thickness ratios and greater pressures, the elastic-plastic collapse controls the failure load. in order to quantify the elastic-plastic buckling capacity of cylindrical shells, an analysis program was carried out by use of the computer code BOSOR5 developed by Bushnell of Lockheed Missiles and Space Company. The analysis was performed for various radius-to-thickness ratios and imperfection amplitudes. The purpose of the analytical program was to compute the buckling strength of underground cylindrical tanks, that are used for storage of nuclear wastes, for realistic geometric imperfections and internal pressure loads. This paper presents the results of the elastic-plastic analyses and compares them with other available information for various pressure loads
An accurate determination of the flux within a slab
International Nuclear Information System (INIS)
Ganapol, B.D.; Lapenta, G.
1993-01-01
During the past decade, several articles have been written concerning accurate solutions to the monoenergetic neutron transport equation in infinite and semi-infinite geometries. The numerical formulations found in these articles were based primarily on the extensive theoretical investigations performed by the open-quotes transport greatsclose quotes such as Chandrasekhar, Busbridge, Sobolev, and Ivanov, to name a few. The development of numerical solutions in infinite and semi-infinite geometries represents an example of how mathematical transport theory can be utilized to provide highly accurate and efficient numerical transport solutions. These solutions, or analytical benchmarks, are useful as open-quotes industry standards,close quotes which provide guidance to code developers and promote learning in the classroom. The high accuracy of these benchmarks is directly attributable to the rapid advancement of the state of computing and computational methods. Transport calculations that were beyond the capability of the open-quotes supercomputersclose quotes of just a few years ago are now possible at one's desk. In this paper, we again build upon the past to tackle the slab problem, which is of the next level of difficulty in comparison to infinite media problems. The formulation is based on the monoenergetic Green's function, which is the most fundamental transport solution. This method of solution requires a fast and accurate evaluation of the Green's function, which, with today's computational power, is now readily available
Lifetime Reliability Assessment of Concrete Slab Bridges
DEFF Research Database (Denmark)
Thoft-Christensen, Palle
A procedure for lifetime assesment of the reliability of short concrete slab bridges is presented in the paper. Corrosion of the reinforcement is the deterioration mechanism used for estimating the reliability profiles for such bridges. The importance of using sensitivity measures is stressed....... Finally the produce is illustrated on 6 existing UK bridges....
All-polymer photonic crystal slab sensor
DEFF Research Database (Denmark)
Hermannsson, Pétur Gordon; Sørensen, Kristian Tølbøl; Vannahme, Christoph
2015-01-01
An all-polymer photonic crystal slab sensor is presented, and shown to exhibit narrow resonant reflection with a FWHM of less than 1 nm and a sensitivity of 31 nm/RIU when sensing media with refractive indices around that of water. This results in a detection limit of 4.5x10-6 RIU when measured...
Slab cooling system design using computer simulation
Lain, M.; Zmrhal, V.; Drkal, F.; Hensen, J.L.M.
2007-01-01
For a new technical library building in Prague computer simulations were carried out to help design of slab cooling system and optimize capacity of chillers. In the paper is presented concept of new technical library HVAC system, the model of the building, results of the energy simulations for
Reinforcement of the concrete base slab of the ATLAS cavern
Maximilien Brice
2002-01-01
Photo 02: UX15 cavern, preparation for concreting of base slab first lift. Photo 05: UX15 cavern, placing of reinforcement for base slab first lift. Photo 07: UX15 cavern, preparation for concreting of base slab first lift. Photo 09: UX15 cavern, placing of reinforcement for base slab first lift. Photo 10: UX15 cavern, view into PX14 shaft above. Photo 12: UX15 cavern, temporary access platform of RB16 tunnel. Photo 15: UJ17 chamber, invert excavation.
Cost analysis of reinforced concrete slabs and columns
Spuś, Piotr
2013-01-01
The construction industry is increasingly looking for solutions that are both simple and effective and that provide cost savings, speed and flexibility of execution. Two-way slabs are a form of construction unique to reinforced concrete comparing with the other major structural materials. It is an efficient, economical, and widely used structural system. The present dissertation aims to analyze and compare costs between four types of slabs: waffle slab with recuperate molds, flat slabs wit...
Development Length for Headed Bars in Slab-Column Joints of RC Slab Bridges
2015-12-04
In accordance with the Caltrans Seismic Design Criteria, the superstructure in a slab bridge should remain essentially elastic and only the pile extensions/columns are permitted to develop inelastic deformations during a seismic event. Hence, the lon...
Modified bond model for shear in slabs under concentrated loads
Lantsoght, E.O.L.; Van der Veen, C.; De Boer, A.
2015-01-01
Slabs subjected to concentrated loads close to supports, as occurring for truck loads on slab bridges, are less studied than beams in shear or slab-column connections in punching. To predict the shear capacity for this case, the Bond Model for concentric punching shear was studied initially.
Nonimaging concentrators for diode-pumped slab lasers
Lacovara, Philip; Gleckman, Philip L.; Holman, Robert L.; Winston, Roland
1991-10-01
Diode-pumped slab lasers require concentrators for high-average power operation. We detail the properties of diode lasers and slab lasers which set the concentration requirements and the concentrator design methodologies that are used, and describe some concentrator designs used in high-average power slab lasers at Lincoln Laboratory.
Control of exceptional points in photonic crystal slabs
DEFF Research Database (Denmark)
Kaminski, Piotr Marek; Taghizadeh, Alireza; Breinbjerg, Olav
2017-01-01
Various ways of controlling the extent of the ring of exceptional points in photonic crystal slabs are investigated. The extent of the ring in photonic crystal slabs is found to vary with the thickness of the slab. This enables recovery of Dirac cones in open, non-Hermitian systems, such as a pho...
Spectrum of resistive MHD modes in cylindrical plasmas
International Nuclear Information System (INIS)
Ryu, C.M.; Grimm, R.C.
1983-07-01
A numerical study of the normal modes of a compressible resistive MHD fluid in cylindrical geometry is presented. Resistivity resolves the shear Alfven and slow magnetosonic continua of ideal MHD into discrete spectra and gives rise to heavily damped modes whose frequencies lie on specific lines in the complex plane. Fast magnetosonic waves are less affected but are also damped. Overstable modes arise from the shear Alfven spectrum. The stabilizing effect of favorable average curvature is shown. Eigenfunctions illustrating the nature of typical normal modes are displayed
Sagnac Interferometer Based Generation of Controllable Cylindrical Vector Beams
Directory of Open Access Journals (Sweden)
Cristian Acevedo
2016-01-01
Full Text Available We report on a novel experimental geometry to generate cylindrical vector beams in a very robust manner. Continuous control of beams’ properties is obtained using an optically addressable spatial light modulator incorporated into a Sagnac interferometer. Forked computer-generated holograms allow introducing different topological charges while orthogonally polarized beams within the interferometer permit encoding the spatial distribution of polarization. We also demonstrate the generation of complex waveforms obtained by combining two orthogonal beams having both radial modulations and azimuthal dislocations.
Periodic Schur process, cylindric partitions and N=2* theory
International Nuclear Information System (INIS)
Iqbal, Amer; Kozcaz, Can; Sohail, Tanweer
2011-01-01
Type IIA string theory compactified on an elliptic CY3-fold gives rise to N=2U(1) gauge theory with an adjoint hypermultiplet. We study the refined open and closed topological string partition functions of this geometry using the refined topological vertex. We show that these partition functions, open and closed, are examples of periodic Schur process and are related to the generating function of the cylindric partitions if the Kaehler parameters are quantized in units of string coupling. The level-rank duality appears as the exchange symmetry of the two Kaehler parameters of the elliptic CY3-fold.
Parallel algorithms for 2-D cylindrical transport equations of Eigenvalue problem
International Nuclear Information System (INIS)
Wei, J.; Yang, S.
2013-01-01
In this paper, aimed at the neutron transport equations of eigenvalue problem under 2-D cylindrical geometry on unstructured grid, the discrete scheme of Sn discrete ordinate and discontinuous finite is built, and the parallel computation for the scheme is realized on MPI systems. Numerical experiments indicate that the designed parallel algorithm can reach perfect speedup, it has good practicality and scalability. (authors)
Possible Laminographic and Tomosynthesis Applications for Wolter Microscope Scan Geometries
International Nuclear Information System (INIS)
Schneberk, D; Jackson, J; Martz, H
2004-01-01
systems. Figure 2 contains a picture of the Wolter optics geometry for inspection. Figure 3 contains an illustration of the scan geometry used in single-plane laminography for flat objects, while figure 4 contains a picture of the scan geometry and motion for a class of tomosynthesis algorithms. The Wolter transmission paths depicted in figure 2 are similar to laminographic and tomosynthesis paths and they provide opportunities to exploit either of these algorithms for removing out of plane blur from Wolter optic images. Other algorithms may arise from the sequence of images obtained by translation through the focus of the Wolter microscope. A variety of LLNL programs have developed iterative and semi-iterative schemes for utilizing prior knowledge from drawings, or other physical measurements to improve defect recognition and inspection of objects. One such algorithm would use the laminographic estimate of each plane as the first estimate of the object function, then iterate on the object function until the forward projections match the acquired sequence of projections translated through the focus of the Wolter microscope. Unlike the laminography and tomosynthesis approaches this particular approach requires a forward model of the projection through the object. We employed an LLNL developed Wolter simulation code [Jackson 2004] to evaluate possible scanning options since a working Wolter was not available. Six synthetic objects were formulated: (1) concentric spheres with a cylindrical void, (2) concentric spheres with a cylindrical inclusion, (3) a sphere with a number of successively smaller sphere-voids arranged in the mid-plane of the object, (4) a sphere with a number of successively smaller sphere inclusions arranged in the mid-plane of the object, (5) a slab object with voids at the entrance plane and at the exit plane of the thickness, and (6) a slab object with inclusions at the entrance plane and at the exit plane of the thickness. Of the six synthetic objects
Absorption factor for cylindrical samples
International Nuclear Information System (INIS)
Sears, V.F.
1984-01-01
The absorption factor for the scattering of X-rays or neutrons in cylindrical samples is calculated by numerical integration for the case in which the absorption coefficients of the incident and scattered beams are not equal. An extensive table of values having an absolute accuracy of 10 -4 is given in a companion report [Sears (1983). Atomic Energy of Canada Limited, Report No. AECL-8176]. In the present paper an asymptotic expression is derived for the absorption factor which can be used with an error of less than 10 -3 for most cases of interest in both neutron inelastic scattering and neutron diffraction in crystals. (Auth.)
Bounds for the minimum step number of knots confined to slabs in the simple cubic lattice
International Nuclear Information System (INIS)
Ishihara, K; Shimokawa, K; Scharein, R; Arsuaga, J; Vazquez, M; Diao, Y
2012-01-01
Volume confinement is a key determinant of the topology and geometry of a polymer. However, the direct relationship between the two is not fully understood. For instance, recent experimental studies have constructed P4 cosmids, i.e. P4 bacteriophages whose genome sequence and length have been artificially engineered and have shown that upon extraction their DNA knot distribution differs from that of wild-type bacteriophage P4. In particular, it was observed that the complexity of the knots decreases sharply with the length of the packed genome. This problem is the motivation of this paper. Here, a polymer is modeled as a self-avoiding polygon on the simple cubic lattice and the confining condition is such that the polygon is bounded between two parallel planes (i.e. bounded within a slab). We estimate the minimum length required for such a polygon to realize a knot type. Our numerical simulations show that in order to realize a prime knot (with up to ten crossings) in a 1-slab (i.e. a slab of height 1), one needs a polygon of length strictly longer than the minimum length needed to realize the same knot when there is no confining condition. In the case of the trefoil knot, we can in fact establish this result analytically by proving that the minimum length required to tie a trefoil in the 1-slab is 26, which is greater than 24, the known minimum length required to tie a trefoil without a confinement condition. Additionally, we find that in the 1-slab not all geometrical realizations of a given knot type are equivalent under BFACF moves. This suggests that in certain confined volumes, knowing the topology of a polymer is not enough to describe all its states. (paper)
Evidence of fire resistance of hollow-core slabs
DEFF Research Database (Denmark)
Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa
is therefore going on in the Netherlands about the fire resistance of hollow-core slabs. In 2014 the producers of hollow-core slabs have published a report of a project called Holcofire containing a collection of 162 fire tests on hollow-core slabs giving for the first time an overview of the fire tests made....... The present paper analyses the evidence now available for assessment of the fire resistance of extruded hollow-core slabs. The 162 fire tests from the Holcofire report are compared against the requirements for testing from the product standard for hollow-core slabs EN1168 and knowledge about the possible......Hollow-core slabs have during the past 50 years comprised a variety of different structures with different cross-sections and reinforcement. At present the extruded hollow-core slabs without cross-reinforcement in the bottom flange and usually round or oval longitudinal channels (holes...
Research on cylindrical indexing cam’s unilateral machining
Directory of Open Access Journals (Sweden)
Junhua Chen
2015-08-01
Full Text Available The cylindrical cam ridge of the indexer is a spatial curved surface, which is difficult to design and machine. The cylindrical cam has some defects after machining because conventional machining methods have inaccuracies. This article aims at proposing a precise way to machine an indexing cam, using basic motion analysis and analytic geometry approach. Analytical methodology is first applied in the cam’s motion analysis, to obtain an error-free cam follower’s trajectory formula, and then separate the continuous trajectory curve by thousandth resolution, to create a three-dimensional discrete trajectory curve. Planar formulae and spherical formulae can be built on the loci. Based on the machine principle, the cutting cutter’s position and orientation will be taken into account. This article calculates the formula set as presented previously and obtains the ultimate cutter path coordinate value. The new error-free cutter path trajectory is called the unilateral machining trajectory. The earned results will compile into numerical control processing schedule. This processing methodology gives a convenient and precision way to manufacture a cylindrical indexing cam. Experimental results are also well supported.
Novel Radon Sub-Slab Suctioning System
DEFF Research Database (Denmark)
Rasmussen, Torben Valdbjørn
2013-01-01
A new principle for radon protection is currently presented which makes use of a system of horizontal pressurised air ducts located within the lower part of the rigid insulation layer of the ground-floor slab. The function of this system is based on the principles of pressure reduction within...... a grid of horizontal air ducts with low pressure which are able to remove air and radon from the ground. Results showed the system to be effective in preventing radon infiltrating from the ground through the ground-floor slab, avoiding high concentrations of radon being accumulated inside houses....... For the system to be effective, the pressure within the ducts must be lower than the pressure inside the house. The new principle was shown to be effective in preventing radon from polluting the indoor air by introducing low pressure in the horizontal grid of air ducts. A lower pressure than the pressure inside...
Silva, Alessandro
1993-01-01
The papers in this wide-ranging collection report on the results of investigations from a number of linked disciplines, including complex algebraic geometry, complex analytic geometry of manifolds and spaces, and complex differential geometry.
Eisenhart, Luther Pfahler
2005-01-01
This concise text by a prominent mathematician deals chiefly with manifolds dominated by the geometry of paths. Topics include asymmetric and symmetric connections, the projective geometry of paths, and the geometry of sub-spaces. 1927 edition.
Upstand Finite Element Analysis of Slab Bridges
O'Brien, Eugene J.; Keogh, D.L.
1998-01-01
For slab bridge decks with wide transverse edge cantilevers, the plane grillage analogy is shown to be an inaccurate method of linear elastic analysis due to variations in the vertical position of the neutral axis. The upstand grillage analogy is also shown to give inaccurate results, this time due to inappropriate modelling of in-plane distortions. An alternative method, known as upstand finite element analysis, is proposed which is sufficiently simple to be used on an everyday basis in the ...
Geometry-specific scaling of detonation parameters from front curvature
International Nuclear Information System (INIS)
Jackson, Scott I.; Short, Mark
2011-01-01
It has previously been asserted that classical detonation curvature theory predicts that the critical diameter and the diameter-effect curve of a cylindrical high-explosive charge should scale with twice the thickness of an analogous two-dimensional explosive slab. The varied agreement of experimental results with this expectation have led some to question the ability of curvature-based concepts to predict detonation propagation in non-ideal explosives. This study addresses such claims by showing that the expected scaling relationship (hereafter referred to d = 2w) is not consistent with curvature-based Detonation Shock Dynamics (DSD) theory.
Directory of Open Access Journals (Sweden)
Salvatore Brischetto
2014-01-01
equilibrium written in orthogonal curvilinear coordinates for the free vibrations of simply supported structures. These equations consider an exact geometry for shells without simplifications. The main novelty is the possibility of a general formulation for different geometries. The equations written in general orthogonal curvilinear coordinates allow the analysis of spherical shell panels and they automatically degenerate into cylindrical shell panel, cylindrical closed shell, and plate cases. Results are proposed for isotropic and orthotropic structures. An exhaustive overview is given of the vibration modes for a number of thickness ratios, imposed wave numbers, geometries, embedded materials, and angles of orthotropy. These results can also be used as reference solutions to validate two-dimensional models for plates and shells in both analytical and numerical form (e.g., closed solutions, finite element method, differential quadrature method, and global collocation method.
International Nuclear Information System (INIS)
Gurevich, L.Eh.; Gliner, Eh.B.
1978-01-01
Problems of investigating the Universe space-time geometry are described on a popular level. Immediate space-time geometries, corresponding to three cosmologic models are considered. Space-time geometry of a closed model is the spherical Riemann geonetry, of an open model - is the Lobachevskij geometry; and of a plane model - is the Euclidean geometry. The Universe real geometry in the contemporary epoch of development is based on the data testifying to the fact that the Universe is infinitely expanding
Superconducting vortex dynamics in cylindrical Nb micro- and nanotubes
Energy Technology Data Exchange (ETDEWEB)
Fomin, Vladimir M. [Institute for Integrative Nanosciences, IFW-Dresden, D-01069 Dresden (Germany); Rezaev, Roman O. [Institute for Integrative Nanosciences, IFW-Dresden, D-01069 Dresden (Germany); Laboratory of Mathematical Physics, Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); Schmidt, Oliver G. [Institute for Integrative Nanosciences, IFW-Dresden, D-01069 Dresden (Germany); Material Systems for Nanoelectronics, Chemnitz University of Technology, D-09107 Chemnitz (Germany)
2012-07-01
Advancements in fabrication of rolled-up micro- and nanotubes including superconductor layers (e.g., InGaAs/GaAs/Nb) open new ways for investigation of the vortex matter in superconductors with curved geometries. Geometry determines the dynamics of vortices in the presence of transport currents in open superconductor micro- and nanotubes subject to a magnetic field orthogonal to the axis. Vortices nucleate periodically at one edge of the tube, subsequently move along the tube under the action of the Lorentz force and denucleate at the opposite edge of the tube. Characteristic times of nonequilibrium vortex dynamics in an open tube are efficiently controlled by the tube radius. The magnetic field, at which the vortices begin to nucleate at the edge of the structure, is increased several times by rolling up a planar film in a tube. This effect is caused not only by a spatial dependence of the magnetic field component normal to the cylindrical surface, but also by correlations between the states of the superconducting order parameter in the opposite areas of the cylindrical surface.
Berkel, van M.; Zwart, Heiko J.; Tamura, N.; Hogeweij, G.M.D.; Inagaki, S.; de Baar, M.R.; Ida, K.
2014-01-01
In this paper, a number of new approximations are introduced to estimate the perturbative diffusivity (χ), convectivity (V), and damping (τ) in cylindrical geometry. For this purpose, the harmonic components of heat waves induced by localized deposition of modulated power are used. The
Experimental and theoretical investigation of column - flat slab joint ductility
International Nuclear Information System (INIS)
Iskhakov, I.; Ribakov, Y.; Shah, A.
2009-01-01
Most modern seismic codes use ductility as one of the basic design parameters. Actually, ductility defines the ability of a structure or its elements to absorb energy by plastic deformations. Until the end of the previous century ductility was defined qualitatively. Most research works related to ductility are focused on structural elements' sections. This study was aimed at complex experimental and theoretical investigation of flat slab-column joints ductility. It is one of the first attempts to obtain quantitative values of joint's ductility for the case of high strength concrete columns and normal strength concrete slabs. It was shown that the flat slab-column joint is a three-dimension (3D) element and its ductility in horizontal and vertical directions are different. This is the main difference between ductility of elements and joint ductility. In case of flat slab-column joints, essential contribution to joint's ductility can be obtained due to the slab's confining effect. Based on experimental data, the authors demonstrate that flat slab-column joint's ductility depends on the joint's confining effect in two horizontal and vertical directions. Furthermore, the influence of slab load intensity and slab reinforcement ratio on the joint's ductility is performed in this study. It is also demonstrated that the effect of the ratio between the slab thickness and the column's section dimension on the ductility parameter is significant. Equations for obtaining a quantitative value of a flat slab-column joint's ductility parameter were developed.
Khalifa, H. E.; Deck, C. P.; Gutierrez, O.; Jacobsen, G. M.; Back, C. A.
2015-02-01
The use of silicon carbide (SiC) composites as structural materials in nuclear applications necessitates the development of a viable joining method. One critical application for nuclear-grade joining is the sealing of fuel within a cylindrical cladding. This paper demonstrates cylindrical joint feasibility using a low activation nuclear-grade joint material comprised entirely of β-SiC. While many papers have considered joining material, this paper takes into consideration the joint geometry and component form factor, as well as the material performance. Work focused specifically on characterizing the strength and permeability performance of joints between cylindrical SiC-SiC composites and monolithic SiC endplugs. The effects of environment and neutron irradiation were not evaluated in this study. Joint test specimens of different geometries were evaluated in their as-fabricated state, as well as after being subjected to thermal cycling and partial mechanical loading. A butted scarf geometry supplied the best combination of high strength and low permeability. A leak rate performance of 2 × 10-9 mbar l s-1 was maintained after thermal cycling and partial mechanical loading and sustained applied force of 3.4 kN, or an apparent strength of 77 MPa. This work shows that a cylindrical SiC-SiC composite tube sealed with a butted scarf endplug provides out-of-pile strength and permeability performance that meets light water reactor design requirements.
Improved semianalytic algorithms for finding the flux from a cylindrical source
International Nuclear Information System (INIS)
Wallace, O.J.
1992-01-01
Hand-calculation methods involving semianalytic approximations of exact flux formulas continue to be useful in shielding calculations because they enable shield design personnel to make quick estimates of dose rates, check calculations made be more exact and time-consuming methods, and rapidly determine the scope of problems. They are also a valuable teaching tool. The most useful approximate flux formula is that for the flux at a lateral detector point from a cylindrical source with an intervening slab shield. Such an approximate formula is given by Rockwell. An improved formula for this case is given by Ono and Tsuro. Shure and Wallace also give this formula together with function tables and a detailed survey of its accuracy. The second section of this paper provides an algorithm for significantly improving the accuracy of the formula of Ono and Tsuro. The flux at a detector point outside the radial and axial extensions of a cylindrical source, again with an intervening slab shield, is another case of interest, but nowhere in the literature is this arrangement of source, shield, and detector point treated. In the third section of this paper, an algorithm for this case is given, based on superposition of sources and the algorithm of Section II. 6 refs., 1 fig., 1 tab
Diffusion from cylindrical waste forms
International Nuclear Information System (INIS)
Thomas, G.F.
1985-05-01
The diffusion of a single component material from a finite cylindrical waste form, initially containing a uniform concentration of the material, is investigated. Under the condition that the cylinder is maintained in a well-stirred bath, expressions for the fractional inventory leached and the leach rate are derived with allowance for the possible permanent immobilization of the diffusant through its decay to a stable product and/or its irreversible reaction with the waste form matrix. The usefulness of the reported results in nuclear waste disposal applications is emphasized. The results reported herein are related to those previously derived at Oak Ridge National Laboratory by Bell and Nestor. A numerical scheme involving the partial decoupling of nested infinite summations and the use of rapidly converging rational approximants is recommended for the efficient implementation of the expressions derived to obtain reliable estimates of the bulk diffusion constant and the rate constant describing the diffusant-waste form interaction from laboratory data
Andreeva, Olga V.; Dement'ev, Dmitry A.; Chekalin, Sergey V.; Kompanets, V. O.; Matveets, Yu. A.; Serov, Oleg B.; Smolovich, Anatoly M.
2002-05-01
The recording geometry and recording media for the method of achromatic wavefront reconstruction are discussed. The femtosecond recording on the thick slabs of dichromated gelatin and the samples of silver-containing porous glass was obtained. The applications of the method to ultrafast laser spectroscopy and to phase conjugation were suggested.
Nematic liquid crystal in a cylindrical sample: Theoretical analysis of the electrical response
Gomes, O. A.; Yednak, C. A. R.; da Silva, B. V. H. V.; Teixeira-Souza, R. T.
2018-02-01
The electrical responses of a nematic liquid crystal sample confined between two cylindrical surfaces are investigated in the framework of elastic continuum theory. The responses are the result of the molecular reorientation induced by both the applied electric field and the cylindrical geometry of the sample. The nematic medium is considered as a parallel RC circuit since the capacitance and the resistance are under the same difference of potential. The electrical properties, including the total electric current, are determined from the molecular reorientation of the director. The elastic anisotropy has been shown to influence substantially the profile of the electrical current, capacitance, and resistance characterizing the equivalent circuit for the medium.
DCXE, Time-Dependent Xe Diffusion in Non-Multiplying Slab
International Nuclear Information System (INIS)
Horikami, K.; Kawasaki, S.
1969-01-01
1 - Nature of physical problem solved: Programme DCXE was designed for the analysis of the diffusion phenomena of xenon in non-multiplying media (slab geometry) and solves the Fick's second diffusion equation with boundary conditions. Initial distribution of xenon in the media at time 0 and 0 value of distribution at both ends of media at any positive time. 2 - Method of solution: Difference approximation is used to solve Fick's second diffusion equation. Strict stability condition is chosen between time and spatial intervals
Useful Solutions for Plane Wave Diffraction by Dielectric Slabs and Wedges
Directory of Open Access Journals (Sweden)
Gianluca Gennarelli
2012-01-01
Full Text Available This work presents an overview of available uniform asymptotic physical optics solutions for evaluating the plane wave diffraction by some canonical geometries of large interest: dielectric slabs and wedges. Such solutions are based on a physical optics approximation of the electric and magnetic equivalent surface currents in the involved scattering integrals. The resulting diffraction coefficients are expressed in terms of the geometrical optics response of the considered structure and the standard transition function of the Uniform Geometrical Theory of Diffraction. Numerical tests and comparisons make evident the effectiveness and reliability of the presented solutions.
DCXE, Time-Dependent Xe Diffusion in Non-Multiplying Slab
Energy Technology Data Exchange (ETDEWEB)
Horikami, K; Kawasaki, S [Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan)
1969-01-01
1 - Nature of physical problem solved: Programme DCXE was designed for the analysis of the diffusion phenomena of xenon in non-multiplying media (slab geometry) and solves the Fick's second diffusion equation with boundary conditions. Initial distribution of xenon in the media at time 0 and 0 value of distribution at both ends of media at any positive time. 2 - Method of solution: Difference approximation is used to solve Fick's second diffusion equation. Strict stability condition is chosen between time and spatial intervals.
Time dependet behaviour of the neutron field in in two interacting cylindrical disks
International Nuclear Information System (INIS)
Hedlund, T.
1979-01-01
The influence of a void on the neutron flux in a moderating system has been studied mainly by the Monte Carlo method. The calculations simulate the decay of the neutron field in a pulsed neutron source measurement. The neutron flux was studied as a function of space, angle, energy and time for a system of two flat cylindrical polyethylene disks. The slab thickness was varied between 1.1 and 4.4 cm and the radius was 9.0 cm. The gap between the slabs was varied from zero to 18 cm. Some calculations have also been made for absorbers in the gap. The purpose of these absorbers was to eliminate the time delay effect for the low velocity neutrons accumulating in the gap. The calculations showed the usefulness of the absorber method. From the results in the time dependent cases the interaction parameter for the two slabs in the corresponding stationary cases has been calculated. The agreement with measurements made by Grosshoeg is good. In the one velocity cases some other methods have also been used to predict the decay rates. For small gap widths the best agreement with the Monte Carlo results was obtained with the variational method. (author)
Spiral modes in cold cylindrical systems
International Nuclear Information System (INIS)
Robe, H.
1975-01-01
The linearized hydrodynamical equations governing the non-axisymmetric free modes of oscillation of cold cylindrical stellar systems are separated in cylindrical coordinates and solved numerically for two models. Short-wavelength unstable modes corresponding to tight spirals do not exist; but there exists an unstable growing mode which has the form of trailing spirals which are quite open. (orig.) [de
Thermal management in inertial fusion energy slab amplifiers
International Nuclear Information System (INIS)
Sutton, S.B.; Albrecht, G.F.
1995-01-01
As the technology associated with the development of solid-state drivers for inertial fusion energy (IFE) has evolved, increased emphasis has been placed on the development of an efficient approach for managing the waste heat generated in the laser media. This paper addresses the technical issues associated with the gas cooling of large aperture slabs, where the laser beam propagates through the cooling fluid. It is shown that the major consequence of proper thermal management is the introduction of simple wedge, or beam steering, into the system. Achieving proper thermal management requires careful consideration of the geometry, cooling fluid characteristics, cooling flow characteristics, as well as the thermal/mechanical/optical characteristics of the laser media. Particularly important are the effects of cooling rate variation and turbulent scattering on the system optical performance. Helium is shown to have an overwhelming advantage with respect to turbulent scattering losses. To mitigate cooling rate variations, the authors introduce the concept of flow conditioning. Finally, optical path length variations across the aperture are calculated. A comparison of two laser materials (S-FAP and YAG) shows the benefit of a nearly a-thermal material on optical variations in the system
Tearing modes in toroidal geometry
International Nuclear Information System (INIS)
Connor, J.W.; Cowley, S.C.; Hastie, R.J.; Hender, T.C.; Hood, A.; Martin, T.J.
1988-01-01
The separation of the cylindrical tearing mode stability problem into a resistive resonant layer calculation and an external marginal ideal magnetohydrodynamic (MHD) calculation (Δ' calculation) is generalized to axisymmetric toroidal geometry. The general structure of this separation is analyzed and the marginal ideal MHD information (the toroidal generalization of Δ') required to discuss stability is isolated. This can then, in principle, be combined with relevant resonant layer calculations to determine tearing mode growth rates in realistic situations. Two examples are given: the first is an analytic treatment of toroidally coupled (m = 1, n = 1) and (m = 2, n = 1) tearing modes in a large aspect ratio torus; the second, a numerical treatment of the toroidal coupling of three tearing modes through finite pressure effects in a large aspect ratio torus. In addition, the use of a coupling integral approach for determining the stability of coupled tearing modes is discussed. Finally, the possibility of using initial value resistive MHD codes in realistic toroidal geometry to determine the necessary information from the ideal MHD marginal solution is discussed
Elliptic-cylindrical analytical flux-rope model for ICMEs
Nieves-Chinchilla, T.; Linton, M.; Hidalgo, M. A. U.; Vourlidas, A.
2016-12-01
We present an analytical flux-rope model for realistic magnetic structures embedded in Interplanetary Coronal Mass Ejections. The framework of this model was established by Nieves-Chinchilla et al. (2016) with the circular-cylindrical analytical flux rope model and under the concept developed by Hidalgo et al. (2002). Elliptic-cylindrical geometry establishes the first-grade of complexity of a series of models. The model attempts to describe the magnetic flux rope topology with distorted cross-section as a possible consequence of the interaction with the solar wind. In this model, the flux rope is completely described in the non-euclidean geometry. The Maxwell equations are solved using tensor calculus consistently with the geometry chosen, invariance along the axial component, and with the only assumption of no radial current density. The model is generalized in terms of the radial dependence of the poloidal current density component and axial current density component. The misalignment between current density and magnetic field is studied in detail for the individual cases of different pairs of indexes for the axial and poloidal current density components. This theoretical analysis provides a map of the force distribution inside of the flux-rope. The reconstruction technique has been adapted to the model and compared with in situ ICME set of events with different in situ signatures. The successful result is limited to some cases with clear in-situ signatures of distortion. However, the model adds a piece in the puzzle of the physical-analytical representation of these magnetic structures. Other effects such as axial curvature, expansion and/or interaction could be incorporated in the future to fully understand the magnetic structure. Finally, the mathematical formulation of this model opens the door to the next model: toroidal flux rope analytical model.
Imaging performance of an isotropic negative dielectric constant slab.
Shivanand; Liu, Huikan; Webb, Kevin J
2008-11-01
The influence of material and thickness on the subwavelength imaging performance of a negative dielectric constant slab is studied. Resonance in the plane-wave transfer function produces a high spatial frequency ripple that could be useful in fabricating periodic structures. A cost function based on the plane-wave transfer function provides a useful metric to evaluate the planar slab lens performance, and using this, the optimal slab dielectric constant can be determined.
Cellular Neural Network Method for Critical Slab with Albedo Boundary Condition
International Nuclear Information System (INIS)
Pirouzmanda, A.; Hadada, K.; Suh, K. Y.
2010-01-01
The neutron transport problems have been studied theoretically and numerically for years. A number of researchers have studied the criticality problems of one-speed neutrons in homogeneous slabs and spheres using various methods. The Chebyshev polynomial approximation method (T N method) has lately been developed and improved for the neutron transport equation in slab geometry. The one-speed time-dependent neutron transport equation using the Cellular Neural Network (CNN) for the vacuum boundary condition has previously been solved. In this paper, we demonstrate the capacity of CNN in calculating the critical slab thickness for different boundary conditions and its variation with moments N. The architecture of the CNN has already been dealt with thoroughly. Essentially, the CNN is used to model a first-order system of the partial differential equations (PDEs). The original equations in the T N approximation are also a set of PDEs. The CNN approach lends itself to analog VLSI implementation. In this study, the CNN model is implemented using the HSpice software package
Structural Test and Analysis of RC Slab After Fire Loading
International Nuclear Information System (INIS)
Chung, Chulhun; Im, Cho Rong; Park, Jaegyun
2013-01-01
In the present study the behavior of fire and the residual strength of fire-ignited RC slabs are investigated by experimental tests and numerical simulations. The fire tests of RC slabs were carried out in a furnace using the ISO 834 standard fire. The load capacity of the cooled RC slabs that were not loaded during the fire tests was evaluated by additional 3 point bending tests. The influence of the proportion of PP (polypropylene) fibers in the RC slabs on the structural behavior of the RC slabs after the fire loading was investigated. The results of the fire tests showed that the maximum temperature of concrete with PP fiber was lower than that of concrete without PP fiber. As the concrete was heated, the ultimate compressive strength decreased and the ultimate strain increased. The load-deflection relations of RC slabs after fire loading were compared by using existing stress-strain-temperature models. The comparison between the numerical analysis and the experimental tests showed that some numerical analyses were reliable and therefore, can be applied to evaluate the ultimate load of RC slabs after fire loading. The ultimate load capacity after cooling down the RC slabs without PP fiber showed a considerable reduction from that of the RC slabs with PP fiber
Structural Test and Analysis of RC Slab After Fire Loading
Energy Technology Data Exchange (ETDEWEB)
Chung, Chulhun; Im, Cho Rong; Park, Jaegyun [Dankook Univ., Yongin (Korea, Republic of)
2013-04-15
In the present study the behavior of fire and the residual strength of fire-ignited RC slabs are investigated by experimental tests and numerical simulations. The fire tests of RC slabs were carried out in a furnace using the ISO 834 standard fire. The load capacity of the cooled RC slabs that were not loaded during the fire tests was evaluated by additional 3 point bending tests. The influence of the proportion of PP (polypropylene) fibers in the RC slabs on the structural behavior of the RC slabs after the fire loading was investigated. The results of the fire tests showed that the maximum temperature of concrete with PP fiber was lower than that of concrete without PP fiber. As the concrete was heated, the ultimate compressive strength decreased and the ultimate strain increased. The load-deflection relations of RC slabs after fire loading were compared by using existing stress-strain-temperature models. The comparison between the numerical analysis and the experimental tests showed that some numerical analyses were reliable and therefore, can be applied to evaluate the ultimate load of RC slabs after fire loading. The ultimate load capacity after cooling down the RC slabs without PP fiber showed a considerable reduction from that of the RC slabs with PP fiber.
Zsámberger, Noémi Kinga; Allcock, Matthew; Erdélyi, Róbert
2018-02-01
Modeling the behavior of magnetohydrodynamic waves in a range of magnetic geometries mimicking solar atmospheric waveguides, from photospheric flux tubes to coronal loops, can offer a valuable contribution to the field of solar magneto-seismology. The present study uses an analytical approach to derive the dispersion relation for magneto-acoustic waves in a magnetic slab of homogeneous plasma enclosed on its two sides by semi-infinite plasma of different densities, temperatures, and magnetic field strengths, providing an asymmetric plasma environment. This is a step further in the generalization of the classic magnetic slab model, which is symmetric about the slab, was developed by Roberts, and is an extension of the work by Allcock & Erdélyi where a magnetic slab is sandwiched in an asymmetric nonmagnetic plasma environment. In contrast to the symmetric case, the dispersion relation governing the asymmetric slab cannot be factorized into separate sausage and kink eigenmodes. The solutions obtained resemble these well-known modes; however, their properties are now mixed. Therefore we call these modes quasi-sausage and quasi-kink modes. If conditions on the two sides of the slab do not differ strongly, then a factorization of the dispersion relation can be achieved for the further analytic study of various limiting cases representing a solar environment. In the current paper, we examine the incompressible limit in detail and demonstrate its possible application to photospheric magnetic bright points. After the introduction of a mechanical analogy, we reveal a relationship between the external plasma and magnetic parameters, which allows for the existence of quasi-symmetric modes.
Coffered slabs as a perspective type of the reinforced concrete structures
Kibkalo Anton; Volkov Mikhail; Vodolagina Anna; Murgul Vera
2016-01-01
The article discusses coffered slabs. In this paper considered the technology of arrangement of this slabs. Cast-in-place and precast ways of construction of coffered slab are reviewed. Сast-in-place and precast coffered slabs has been analysed in this article. Among other things construction of coffered slabs has an economical and technical advantages.
Coffered slabs as a perspective type of the reinforced concrete structures
Directory of Open Access Journals (Sweden)
Kibkalo Anton
2016-01-01
Full Text Available The article discusses coffered slabs. In this paper considered the technology of arrangement of this slabs. Cast-in-place and precast ways of construction of coffered slab are reviewed. Сast-in-place and precast coffered slabs has been analysed in this article. Among other things construction of coffered slabs has an economical and technical advantages.
Investigation of Surface Phenomena in Shocked Tin in Converging Geometry
Energy Technology Data Exchange (ETDEWEB)
Rousculp, Christopher L. [Los Alamos National Laboratory; Oro, David Michael [Los Alamos National Laboratory; Griego, Jeffrey Randall [Los Alamos National Laboratory; Turchi, Peter John [Los Alamos National Laboratory; Reinovsky, Robert Emil [Los Alamos National Laboratory; Bradley, Joseph Thomas [Los Alamos National Laboratory; Cheng, Baolian [Los Alamos National Laboratory; Freeman, Matthew Stouten [Los Alamos National Laboratory; Patten, Austin Randall [Los Alamos National Laboratory
2016-03-21
There is great interest in the behavior of the free surface of tin under shock loading. While it is known that meso-scale surface imperfections can seed the Richtmyer- Meshkov Instability (RMI) for a surface that is melted on release, much less is known about a tin surface that is solid, but plastically deforming. Here material properties such as shear and yield strength come into play especially in converging geometry. Previous experiments have been driven by direct contact HE. Usually a thin, flat target coupon is fielded with various single-mode, sinusoidal, machined, profiles on the free surface. The free surface is adjacent to either vacuum or an inert receiver gas. Most of these previous driver/target configurations have been nominal planer geometry. With modern HE it has been straightforward to shock tin into melt on release. However it has been challenging to achieve a low enough pressure for solid state on release. Here we propose to extend the existing base of knowledge to include the behavior of the free surface of tin in cylindrical converging geometry. By shock loading a cylindrical tin shell with a magnetically driven cylindrical liner impactor, the free surface evolution can be diagnosed with proton radiography. With the PHELIX capacitor bank, the drive can easily be varied to span the pressure range to achieve solid, mixed, and liquid states on release. A conceptual cylindrical liner and target is shown in Figure 1.
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
Diffusion in a cylindrical plasma
International Nuclear Information System (INIS)
Reid, J.
1977-04-01
Modern plasma containment devices, such as the Tokamak, employ magnetic fields which are toroidal in shape. They are able to contain a plasma for times approaching a second. Magnetohydrodynamics (M.H.D.) is one of the most attractive theoretical methods for understanding their behaviour, but the equations involved are complex non-linear partial differential equations, and analytic methods are not available for their solution. Numerical methods must be used. A model system of equations representing a cylindrical plasma with no axial variation is considered. It is convenient to introduce a flux function psi for the component of the magnetic field directed around the axis of the cylinder, called the poloidal field, and the M.H.D. equations are rewritten in terms of psi. This produces a set of highly coupled equations describing the evolution of the flux function, the axial field and the plasma pressure. Various steps are taken to gain a better understanding of the properties of these equations. (author)
DESIGN OF A CONCRETE SLAB FOR STORAGE OF SNF AND HLW CASKS
International Nuclear Information System (INIS)
J. Bisset
2005-01-01
This calculation documents the design of the Spent Nuclear Fuel (SNF) and High-Level Waste (HLW) Cask storage slab for the Aging Area. The design is based on the weights of casks that may be stored on the slab, the weights of vehicles that may be used to move the casks, and the layout shown on the sketch for a 1000 Metric Ton of Heavy Metal (MTHM) storage pad on Attachment 2, Sht.1 of the calculation 170-C0C-C000-00100-000-00A (BSC 2004a). The analytical model used herein is based on the storage area for 8 vertical casks. To simplify the model, the storage area of the horizontal concrete modules and their related shield walls is not included. The heavy weights of the vertical storage casks and the tensile forces due to pullout at the anchorages will produce design moments and shear forces that will envelope those that would occur in the storage area of the horizontal modules. The design loadings will also include snow and live loads. In addition, the design will also reflect pertinent geotechnical data. This calculation will document the preliminary thickness and general reinforcing steel requirements for the slab. This calculation also documents the initial design of the cask anchorage. Other slab details are not developed in this calculation. They will be developed during the final design process. The calculation also does not include the evaluation of the effects of cask drop loads. These will be evaluated in this or another calculation when the exact cask geometry is known
Radiative transfer model for contaminated rough slabs.
Andrieu, François; Douté, Sylvain; Schmidt, Frédéric; Schmitt, Bernard
2015-11-01
We present a semi-analytical model to simulate the bidirectional reflectance distribution function (BRDF) of a rough slab layer containing impurities. This model has been optimized for fast computation in order to analyze massive hyperspectral data by a Bayesian approach. We designed it for planetary surface ice studies but it could be used for other purposes. It estimates the bidirectional reflectance of a rough slab of material containing inclusions, overlaying an optically thick media (semi-infinite media or stratified media, for instance granular material). The inclusions are assumed to be close to spherical and constituted of any type of material other than the ice matrix. It can be any other type of ice, mineral, or even bubbles defined by their optical constants. We assume a low roughness and we consider the geometrical optics conditions. This model is thus applicable for inclusions larger than the considered wavelength. The scattering on the inclusions is assumed to be isotropic. This model has a fast computation implementation and thus is suitable for high-resolution hyperspectral data analysis.
Domino, J.; Bourke, J. R.; Naslund, H. R.; Nikulin, A.
2017-12-01
A gap in the volcanic arc across the Pampean section of the Chilean subduction zone (28-33°S) breaks up the otherwise predictable pattern of South American volcanism. This gap in the volcanic front, accompanied by diminished interplate seismic activity, correlates to the onset of flat slab subduction of the segmented Nazca Plate. We present results of a multidisciplinary study combining geophysical and petrologic observations, focused on the processes influencing subduction zone geometry in Central Chile and their impact on regional seismic and volcanic activity. Through a broad-scale receiver function survey obtained from existing permanent stations in Central Chile, we imaged the position of the subducting Nazca Plate beneath South America and created corresponding depth-converted images to further interpret the underlying structure. This survey reveals evidence of a highly anisotropic layer above the subducting slab beneath station GO03 of the Chilean National Seismic Network, possibly indicating an area of extensive hydration triggered by fluid release from the subducting plate. By imaging the interplate region to the north of the flat slab, we constrained the lateral extent of the anisotropic layer and made an attempt to correlate the character of the identified geophysical anomaly to geochemical patterns exhibited by active volcanoes in the region. A detailed compilation of available geochemical data was done to understand any existing cross-arc or along-arc variations that could be attributed to the geometry of the subducting slab over time, focused on trace element trends that are indicative of interactions with hydrated mantle. Our results indicate a correlation between the observed anisotropic layer and changes in the geochemistry of the closest spatial volcanism through time as the geometry of flat slab subduction evolved. By combining the receiver function results with initial petrologic observations, it is our goal to further constrain the inherent
Pulsed neutron determination of anisotropic diffusion constants in multi-layered slabs
International Nuclear Information System (INIS)
Sri Ram, K.
1978-01-01
Anisotropic neutron diffusion parameters for graphite and plexiglas slab assemblies were calculated using one-dimensional discrete ordinates code ANISN, and also Case's eigenfunction expansion technique as suggested by Leonard. These calculated values were checked with the pulsed neutron experimental results as well as simple diffusion theory calculations of Spinrad. Relatively little experimental work has been done with heterogeneous assemblies which do not contain voids. The present comparison shows that the experimental results agree well with transport theory calculations. It appears from the results and inter-comparison of this work in simple geometries, that the pulsed neutron method can yield accurate experimental anisotropic diffusion constants, and can therefore be applied to more complicated geometries which may be difficult to calculate. (author)
Exposure rates from concrete covered cylindrical units containing radioactive waste
International Nuclear Information System (INIS)
Hedemann Jensen, P.
1983-03-01
Exposure rates from cylindrical waste units containing the nuclides 60 Co, 134 Cs and 137 Cs homogeneously mixed in a solidification product have been calculated. Analyses have been made for single drums and for two disposal geometries, one with the units placed below ground near the surface in a circular geometry, and one with the units placed on the ground in a pile behind a concrete wall. Due to self-shielding of the units, the exposure rate from the two geometries will be a factor of only 10 - 20 higher than from a single unit, even without soil or wall shielding. With one meter of soil above the circular pile below ground, a reduction factor of 5.10 3 to 5.10 4 can be achieved, depending on the nuclide considered. Placing a one-meter concrete wall in front of the drum pile on the ground gives rise to a reduction factor in the range of 5.10 5 to 2.10 7 . (author)
External Cylindrical Nozzle with Controlled Vacuum
Directory of Open Access Journals (Sweden)
V. N. Pil'gunov
2015-01-01
Full Text Available There is a developed design of the external cylindrical nozzle with a vacuum camera. The paper studies the nozzle controllability of flow rate via regulated connection of the evacuated chamber to the atmosphere through an air throttle. Working capacity of the nozzle with inlet round or triangular orifice are researched. The gap is provided in the nozzle design between the external wall of the inlet orifice and the end face of the straight case in the nozzle case. The presented mathematical model of the nozzle with the evacuated chamber allows us to estimate the expected vacuum amount in the compressed section of a stream and maximum permissible absolute pressure at the inlet orifice. The paper gives experimental characteristics of the fluid flow process through the nozzle for different values of internal diameter of a straight case and an extent of its end face remoteness from an external wall of the inlet orifice. It estimates how geometry of nozzle constructive elements influences on the volume flow rate. It is established that the nozzle capacity significantly depends on the shape of inlet orifice. Triangular orifice nozzles steadily work in the mode of completely filled flow area of the straight case at much more amounts of the limit pressure of the flow. Vacuum depth in the evacuated chamber also depends on the shape of inlet orifice: the greatest vacuum is reached in a nozzle with the triangular orifice which 1.5 times exceeds the greatest vacuum with the round orifice. Possibility to control nozzle capacity through the regulated connection of the evacuated chamber to the atmosphere was experimentally estimated, thus depth of flow rate regulation of the nozzle with a triangular orifice was 45% in comparison with 10% regulation depth of the nozzle with a round orifice. Depth of regulation calculated by a mathematical model appeared to be much more. The paper presents experimental dependences of the flow coefficients of nozzle input orifice
Some thermo-physical properties of yam cuts of two geometries ...
African Journals Online (AJOL)
The effects of variation of temperature (-18 to 33°C) and geometries (slab and cylinder) on some thermo-physical properties of white yam were investigated. The measured parameters were density, specific heat, and thermal diffusivity at constant moisture level of 72.7% ± 0.69 (wet basis) using transient heat transfer method ...
Effect of sample geometry on bulk relative density of hot-mix asphalt mixes
CSIR Research Space (South Africa)
Anochie-Boateng, Joseph
2011-09-01
Full Text Available with different number of cut/cored surfaces. Significant variations in voids were observed in the HMA core and beam samples from the same compacted slabs. The objective of this paper is to present the findings of the effect of specimen geometry and cut surfaces...
Study of fire-resistance of reinforced concrete slab of a new type
Directory of Open Access Journals (Sweden)
Kalmykov Oleg
2017-01-01
Full Text Available Reinforced concrete structures with complex inner geometry under the effect of high temperatures considering void former materials were examined. The analysis of strain-stress state of new type of architectural and construction system ‘Monofant’ under the effect of high temperature heating in standard fire mode, considering the change of design pattern was carried out. Numerical study of concrete slab with given reinforcement and complex inner geometry was carried out with use of software packages based on finite element method. Temperature fields throughout the depth of cross section of the slab of new type of architectural and construction system ‘Monofant’ upon heating in standard fire mode for time interval 0-240 min. were obtained. The carrying capacity of sections exposed to high temperatures was determined by deformation method. Offered the algorithm that considers the transformation of design patterns depending on temperature values and excessive pressure in thermal insulation cavities taking into account influence of deformation fields on temperature distribution.
Meyer, Walter J
2006-01-01
Meyer''s Geometry and Its Applications, Second Edition, combines traditional geometry with current ideas to present a modern approach that is grounded in real-world applications. It balances the deductive approach with discovery learning, and introduces axiomatic, Euclidean geometry, non-Euclidean geometry, and transformational geometry. The text integrates applications and examples throughout and includes historical notes in many chapters. The Second Edition of Geometry and Its Applications is a significant text for any college or university that focuses on geometry''s usefulness in other disciplines. It is especially appropriate for engineering and science majors, as well as future mathematics teachers.* Realistic applications integrated throughout the text, including (but not limited to): - Symmetries of artistic patterns- Physics- Robotics- Computer vision- Computer graphics- Stability of architectural structures- Molecular biology- Medicine- Pattern recognition* Historical notes included in many chapters...
Indian Academy of Sciences (India)
algebraic geometry but also in related fields like number theory. ... every vector bundle on the affine space is trivial. (equivalently ... les on a compact Riemann surface to unitary rep- ... tial geometry and topology and was generalised in.
International Nuclear Information System (INIS)
Sloane, Peter
2007-01-01
We adapt the spinorial geometry method introduced in [J. Gillard, U. Gran and G. Papadopoulos, 'The spinorial geometry of supersymmetric backgrounds,' Class. Quant. Grav. 22 (2005) 1033 [ (arXiv:hep-th/0410155)
Energy Technology Data Exchange (ETDEWEB)
Sloane, Peter [Department of Mathematics, King' s College, University of London, Strand, London WC2R 2LS (United Kingdom)
2007-09-15
We adapt the spinorial geometry method introduced in [J. Gillard, U. Gran and G. Papadopoulos, 'The spinorial geometry of supersymmetric backgrounds,' Class. Quant. Grav. 22 (2005) 1033 [ (arXiv:hep-th/0410155)
Radon Sub-slab Suctioning System Integrated in Insulating Layer
DEFF Research Database (Denmark)
Rasmussen, Torben Valdbjørn
2013-01-01
This poster presents a new radon sub-slab suctioning system. This system makes use of a grid of horizontal pressurised air ducts located within the lower part of the rigid insulation layer of the ground floor slab. For this purpose a new system of prefabricated lightweight elements is introduced...
Ultimate deformation capacity of reinforced concrete slabs underblast load
Doormaal, J.C.A.M. van; Weerheijm, J.
1996-01-01
In this paper a test method to determine the deformation capacity and the resistance-deformation curve of blast-loaded slabs is described. This method was developed at TNO-PML. The method has been used to determine the ultimate deformation capacity of some simply supported reinforced concrete slabs
On Early Age Crack Formation in FRC Slabs
DEFF Research Database (Denmark)
Olesen, John Forbes; Stang, Henrik
1997-01-01
The problem of early age crack formation in FRC slabs due to restrained temperature and shrinkage deformations, is given an analytical treatment. A model taking into account the ageing properties of the tensile softening curve and the continued development in the temperature and shrinkage...... deformations after crack initiation, is presented. Based on this model a design strategy for FRC slabs is outlined....
Surface Waves Propagating on Grounded Anisotropic Dielectric Slab
Directory of Open Access Journals (Sweden)
Zhuozhu Chen
2018-01-01
Full Text Available This paper investigates the characteristics of surface waves propagating on a grounded anisotropic dielectric slab. Distinct from the existing analyses that generally assume that the fields of surface wave uniformly distribute along the transverse direction of the infinitely large grounded slab, our method takes into account the field variations along the transverse direction of a finite-width slab. By solving Maxwell’s equations in closed-form, it is revealed that no pure transverse magnetic (TM or transverse electric (TE mode exists if the fields are non-uniformly distributed along the transverse direction of the grounded slab. Instead, two hybrid modes, namely quasi-TM and quasi-TE modes, are supported. In addition, the propagation characteristics of two hybrid modes supported by the grounded anisotropic slab are analyzed in terms of the slab thickness, slab width, as well as the relative permittivity tensor of the anisotropic slab. Furthermore, different methods are employed to compare the analyses, as well as to validate our derivations. The proposed method is very suitable for practical engineering applications.
Evolution and diversity of subduction zones controlled by slab width
Schellart, W. P.; Freeman, J.A.; Stegman, D. R.; Moresi, L.; May, D.
2007-01-01
Subducting slabs provide the main driving force for plate motion and flow in the Earth's mantle, and geodynamic, seismic and geochemical studies offer insight into slab dynamics and subduction-induced flow. Most previous geodynamic studies treat subduction zones as either infinite in trench-parallel
Cylindrical Taylor states conserving total absolute magnetic helicity
Low, B. C.; Fang, F.
2014-09-01
The Taylor state of a three-dimensional (3D) magnetic field in an upright cylindrical domain V is derived from first principles as an extremum of the total magnetic energy subject to a conserved, total absolute helicity Habs. This new helicity [Low, Phys. Plasmas 18, 052901 (2011)] is distinct from the well known classical total helicity and relative total helicity in common use to describe wholly-contained and anchored fields, respectively. A given field B, tangential along the cylindrical side of V, may be represented as a unique linear superposition of two flux systems, an axially extended system along V and a strictly transverse system carrying information on field-circulation. This specialized Chandrasekhar-Kendall representation defines Habs and permits a neat formulation of the boundary-value problem (BVP) for the Taylor state as a constant-α force-free field, treating 3D wholly-contained and anchored fields on the same conceptual basis. In this formulation, the governing equation is a scalar integro-partial differential equation (PDE). A family of series solutions for an anchored field is presented as an illustration of this class of BVPs. Past treatments of the constant-α field in 3D cylindrical geometry are based on a scalar Helmholtz PDE as the governing equation, with issues of inconsistency in the published field solutions discussed over time in the journal literature. The constant-α force-free equation reduces to a scalar Helmholtz PDE only as special cases of the 3D integro-PDE derived here. In contrast, the constant-α force-free equation and the scalar Helmholtz PDE are absolutely equivalent in the spherical domain as discussed in Appendix. This theoretical study is motivated by the investigation of the Sun's corona but the results are also relevant to laboratory plasmas.
Cylindrical fabric-confined soil structures
Harrison, Richard A.
A cylindrical fabric-soil structural concept for implementation on the moon and Mars which provides many advantages is proposed. The most efficient use of fabric is to fashion it into cylindrical tubes, creating cylindrical fabric-confined soil structures. The length, diameter, and curvature of the tubes will depend on the intended application. The cylindrical hoop forces provide radial confinement while end caps provide axial confinement. One of the ends is designed to allow passage of the soil into the fabric tube before sealing. Transportation requirements are reduced due to the low mass and volume of the fabric. Construction requirements are reduced due to the self-erection capability via the pneumatic exoskeleton. Maintenance requirements are reduced due to the passive nature of the concept. The structure's natural ductility is well suited for any seismic activity.
Cylindrical-shaped nanotube field effect transistor
Hussain, Muhammad Mustafa
2015-12-29
A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.
Cylindrical-shaped nanotube field effect transistor
Hussain, Muhammad Mustafa; Fahad, Hossain M.; Smith, Casey E.; Rojas, Jhonathan Prieto
2015-01-01
A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.
Micromagnetic simulations of cylindrical magnetic nanowires
Ivanov, Yurii P.; Chubykalo-Fesenko, O.
2015-01-01
This chapter reviews micromagnetic simulations of cylindrical magnetic nanowires and their ordered arrays. It starts with a description of the theoretical background of micromagnetism. The chapter discusses main magnetization reversal modes, domain
Plasma waves in an inhomogeneous cylindrical plasma
International Nuclear Information System (INIS)
Pesic, S.S.
1976-01-01
The complete dispersion equation governing small amplitude plasma waves propagating in an inhomogeneous cylindrical plasma confined by a helical magnetic field is solved numerically. The efficiency of the wave energy thermalization in the lower hybrid frequency range is studied
Gravitational Instability of Cylindrical Viscoelastic Medium ...
Indian Academy of Sciences (India)
similar to that of viscoelastic fluid where both properties work together. They also ... cylindrical gravitational waves provides a strong motivation in this regard. .... which represents the solenoidal character of the magnetic field and the total stress.
Storm-time slab thickness at low latitudes
International Nuclear Information System (INIS)
Chauhan, N.S.; Gurm, H.S.
1981-01-01
The ATS-6 data for a period of 1975-76 is used for the study of slab thickness during two moderate storms (Ksub(p) - ) around the crest of the anomaly, Ahmedabad and a very great (Ksub(p) + ) outside the equatorial anomaly region, Delhi. While at Ahmedabad, on the average, the slab thickness is found to be above the frequency. Comparison of slab thickness with foF2 and the equatorial magnetic record (for Ahmedabad only) shows that the foF2 changes alone cannot be held responsible for the slab thickness variation and thus entry of the plasma flux from the plasmasphere cannot be ruled out. The pressure variation effect of storm-time heating on the slab thickness at Ahmedabad is that even for Ksub(p)=8, the thermal expansion and the contraction effects are unable to explain complete quantitative and qualitative features of the observations
Shear strength of end slabs of prestressed concrete reactor vessels
International Nuclear Information System (INIS)
Cheung, K.C.; Gotschall, H.L.; Liu, T.C.
1975-01-01
Prestressed concrete reactor vessels (PCRV's) have been adopted for primary containments in most large high-temperature gas-cooled reactor installations. The most common configuration for PCRVs is a right-vertical cylinder with thick end slabs. In order to assess the integrity of a PCRV it is necessary to predict the ultimate strength of the end slabs. The complexity of the basic mechanism of shear failure in the PCRV end slabs has thus far prohibited the development of a completely analytical solution. However, many experimental investigations of PCRV end slabs have been conducted over the past decade. This information makes it possible to establish empirical formulae for the ultimate strength of PCRV end slabs. The basis and development of an empirical shear-flexure interaction expression is presented. (Auth.)
Wu, J. E.; Suppe, J.; Renqi, L.; Kanda, R. V. S.
2014-12-01
Published plate reconstructions typically show the Izu-Bonin Marianas arc (IBM) forming as a result of long-lived ~50 Ma Pacific subduction beneath the Philippine Sea. These reconstructions rely on the critical assumption that the Philippine Sea was continuously coupled to the Pacific during the lifetime of the IBM arc. Because of this assumption, significant (up to 1500 km) Pacific trench retreat is required to accommodate the 2000 km of Philippine Sea/IBM northward motion since the Eocene that is constrained by paleomagnetic data. In this study, we have mapped subducted slabs of mantle lithosphere from MITP08 global seismic tomography (Li et al., 2008) and restored them to a model Earth surface to constrain plate tectonic reconstructions. Here we present two subducted slab constraints that call into question current IBM arc reconstructions: 1) The northern and central Marianas slabs form a sub-vertical 'slab wall' down to maximum 1500 km depths in the lower mantle. This slab geometry is best explained by a near-stationary Marianas trench that has remained +/- 250 km E-W of its present-day position since ~45 Ma, and does not support any significant Pacific slab retreat. 2) A vanished ocean is revealed by an extensive swath of sub-horizontal slabs at 700 to 1000 km depths in the lower mantle below present-day Philippine Sea to Papua New Guinea. We call this vanished ocean the 'East Asian Sea'. When placed in an Eocene plate reconstruction, the East Asian Sea fits west of the reconstructed Marianas Pacific trench position and north of the Philippine Sea plate. This implies that the Philippine Sea and Pacific were not adjacent at IBM initiation, but were in fact separated by a lost ocean. Here we propose a new IBM arc reconstruction constrained by subducted slabs mapped under East Asia. At ~50 Ma, the present-day IBM arc initiated at equatorial latitudes from East Asian Sea subduction below the Philippine Sea. A separate arc was formed from Pacific subduction below
Time-dependent patterns in quasivertical cylindrical binary convection
Alonso, Arantxa; Mercader, Isabel; Batiste, Oriol
2018-02-01
This paper reports on numerical investigations of the effect of a slight inclination α on pattern formation in a shallow vertical cylindrical cell heated from below for binary mixtures with a positive value of the Soret coefficient. By using direct numerical simulation of the three-dimensional Boussinesq equations with Soret effect in cylindrical geometry, we show that a slight inclination of the cell in the range α ≈0.036 rad =2∘ strongly influences pattern selection. The large-scale shear flow (LSSF) induced by the small tilt of gravity overcomes the squarelike arrangements observed in noninclined cylinders in the Soret regime, stratifies the fluid along the direction of inclination, and produces an enhanced separation of the two components of the mixture. The competition between shear effects and horizontal and vertical buoyancy alters significantly the dynamics observed in noninclined convection. Additional unexpected time-dependent patterns coexist with the basic LSSF. We focus on an unsual periodic state recently discovered in an experiment, the so-called superhighway convection state (SHC), in which ascending and descending regions of fluid move in opposite directions. We provide numerical confirmation that Boussinesq Navier-Stokes equations with standard boundary conditions contain the essential ingredients that allow for the existence of such a state. Also, we obtain a persistent heteroclinic structure where regular oscillations between a SHC pattern and a state of nearly stationary longitudinal rolls take place. We characterize numerically these time-dependent patterns and investigate the dynamics around the threshold of convection.
Local and global Casimir energies for a semitransparent cylindrical shell
International Nuclear Information System (INIS)
Cavero-Pelaez, Ines; Milton, Kimball A; Kirsten, Klaus
2007-01-01
The local Casimir energy density and the global Casimir energy for a massless scalar field associated with a λδ-function potential in a (3 + 1)-dimensional circular cylindrical geometry are considered. The global energy is examined for both weak and strong coupling, the latter being the well-studied Dirichlet cylinder case. For weak coupling, through O(λ 2 ), the total energy is shown to vanish by both analytic and numerical arguments, based both on Green's-function and zeta-function techniques. Divergences occurring in the calculation are shown to be absorbable by renormalization of physical parameters of the model. The global energy may be obtained by integrating the local energy density only when the latter is supplemented by an energy term residing precisely on the surface of the cylinder. The latter is identified as the integrated local energy density of the cylindrical shell when the latter is physically expanded to have finite thickness. Inside and outside the δ-function shell, the local energy density diverges as the surface of the shell is approached; the divergence is weakest when the conformal stress tensor is used to define the energy density. A real global divergence first occurs in O(λ 3 ), as anticipated, but the proof is supplied here for the first time; this divergence is entirely associated with the surface energy and does not reflect divergences in the local energy density as the surface is approached
Implosion of Cylindrical Cavities via Short Duration Impulsive Loading
Huneault, Justin; Higgins, Andrew
2014-11-01
An apparatus has been developed to study the collapse of a cylindrical cavity in gelatin subjected to a symmetric impact-driven impulsive loading. A gas-driven annular projectile is accelerated to approximately 50 m/s, at which point it impacts a gelatin casting confined by curved steel surfaces that allow a transition from an annular geometry to a cylindrically imploding motion. The implosion is visualized by a high-speed camera through a window which forms the top confining wall of the implosion cavity. The initial size of the cavity is such that the gelatin wall is two to five times thicker than the impacting projectile. Thus, during impact the compression wave which travels towards the cavity is closely followed by a rarefaction resulting from the free surface reflection of the compression wave in the projectile. As the compression wave in the gelatin reaches the inner surface, it will also reflect as a rarefaction wave. The interaction between the rarefaction waves from the gelatin and projectile free surfaces leads to large tensile stresses resulting in the spallation of a relatively thin shell. The study focuses on the effect of impact parameters on the thickness and uniformity of the imploding shell formed by the cavitation in the imploding gelatin cylinder.
Damping Analysis of Cylindrical Composite Structures with Enhanced Viscoelastic Properties
Kliem, Mathias; Høgsberg, Jan; Vanwalleghem, Joachim; Filippatos, Angelos; Hoschützky, Stefan; Fotsing, Edith-Roland; Berggreen, Christian
2018-04-01
Constrained layer damping treatments are widely used in mechanical structures to damp acoustic noise and mechanical vibrations. A viscoelastic layer is thereby applied to a structure and covered by a stiff constraining layer. When the structure vibrates in a bending mode, the viscoelastic layer is forced to deform in shear mode. Thus, the vibration energy is dissipated as low grade frictional heat. This paper documents the efficiency of passive constrained layer damping treatments for low frequency vibrations of cylindrical composite specimens made of glass fibre-reinforced plastics. Different cross section geometries with shear webs have been investigated in order to study a beneficial effect on the damping characteristics of the cylinder. The viscoelastic damping layers are placed at different locations within the composite cylinder e.g. circumferential and along the neutral plane to evaluate the location-dependent efficiency of constrained layer damping treatments. The results of the study provide a thorough understanding of constrained layer damping treatments and an improved damping design of the cylindrical composite structure. The highest damping is achieved when placing the damping layer in the neutral plane perpendicular to the bending load. The results are based on free decay tests of the composite structure.
International Nuclear Information System (INIS)
Yee, K.S.
1980-01-01
It has been observed that the exposure of dielectrics to electron beams can produce an electric field of sufficient magnitude to cause dielectric breakdown. The present investigations will be directed to calculate the electric field intensity in dielectrics under spherical and cylindrical geometries. In the spherical geometry the method of multiple images renders the full numerical calculation unnecessary, whereas in a finite length cylindrical geometry the full numerical calculation seems to be inevitable. A description and results of the spherical geometry are presented and a more detailed presentation of the finite cylinder geometry is given
Laminar forced convection in a cylindrical collinear ohmic sterilizer
Directory of Open Access Journals (Sweden)
Pesso Tommaso
2017-01-01
Full Text Available The present work deals with a thermo-fluid analysis of a collinear cylindrical ohmic heater in laminar flow. The geometry of interest is a circular electrically insulated glass pipe with two electrodes at the pipe ends. For this application, since the electrical conductivity of a liquid food depends strongly on the temperature, the thermal analysis of an ohmic heater requires the simultaneous solution of the electric and thermal fields. In the present work the analysis involves decoupling the previous fields by means of an iterative procedure. The thermal field has been calculated using an analytical solution, which leads to fast calculations for the temperature distribution in the heater. Some considerations of practical interest for the design are also given.
Ductile fracture of cylindrical vessels containing a large flaw
Erdogan, F.; Irwin, G. R.; Ratwani, M.
1976-01-01
The fracture process in pressurized cylindrical vessels containing a relatively large flaw is considered. The flaw is assumed to be a part-through or through meridional crack. The flaw geometry, the yield behavior of the material, and the internal pressure are assumed to be such that in the neighborhood of the flaw the cylinder wall undergoes large-scale plastic deformations. Thus, the problem falls outside the range of applicability of conventional brittle fracture theories. To study the problem, plasticity considerations are introduced into the shell theory through the assumptions of fully-yielded net ligaments using a plastic strip model. Then a ductile fracture criterion is developed which is based on the concept of net ligament plastic instability. A limited verification is attempted by comparing the theoretical predictions with some existing experimental results.
Damping analysis of cylindrical composite structures with enhanced viscoelastic properties
DEFF Research Database (Denmark)
Kliem, Mathias; Høgsberg, Jan Becker; Vanwalleghem, Joachim
2018-01-01
is forced to deform in shear mode. Thus, the vibration energy is dissipated as low grade frictional heat. This paper documents the eﬃciency of passive constrained layer damping treatments for low frequency vibrations of cylindrical composite specimens made of glass ﬁbre-reinforced plastics. Diﬀerent cross...... section geometries with shear webs have been investigated in order to study a beneﬁcial eﬀect on the damping characteristics of the cylinder. The viscoelastic damping layers are placed at diﬀerent locations within the composite cylinder e.g. circumferential and along the neutral plane to evaluate...... in the neutral plane perpendicular to the bending load. The results are based on free decay tests of the composite structure....
Lai, Changliang; Wang, Junbiao; Liu, Chuang
2014-10-01
Six typical composite grid cylindrical shells are constructed by superimposing three basic types of ribs. Then buckling behavior and structural efficiency of these shells are analyzed under axial compression, pure bending, torsion and transverse bending by finite element (FE) models. The FE models are created by a parametrical FE modeling approach that defines FE models with original natural twisted geometry and orients cross-sections of beam elements exactly. And the approach is parameterized and coded by Patran Command Language (PCL). The demonstrations of FE modeling indicate the program enables efficient generation of FE models and facilitates parametric studies and design of grid shells. Using the program, the effects of helical angles on the buckling behavior of six typical grid cylindrical shells are determined. The results of these studies indicate that the triangle grid and rotated triangle grid cylindrical shell are more efficient than others under axial compression and pure bending, whereas under torsion and transverse bending, the hexagon grid cylindrical shell is most efficient. Additionally, buckling mode shapes are compared and provide an understanding of composite grid cylindrical shells that is useful in preliminary design of such structures.
Untangling Slab Dynamics Using 3-D Numerical and Analytical Models
Holt, A. F.; Royden, L.; Becker, T. W.
2016-12-01
Increasingly sophisticated numerical models have enabled us to make significant strides in identifying the key controls on how subducting slabs deform. For example, 3-D models have demonstrated that subducting plate width, and the related strength of toroidal flow around the plate edge, exerts a strong control on both the curvature and the rate of migration of the trench. However, the results of numerical subduction models can be difficult to interpret, and many first order dynamics issues remain at least partially unresolved. Such issues include the dominant controls on trench migration, the interdependence of asthenospheric pressure and slab dynamics, and how nearby slabs influence each other's dynamics. We augment 3-D, dynamically evolving finite element models with simple, analytical force-balance models to distill the physics associated with subduction into more manageable parts. We demonstrate that for single, isolated subducting slabs much of the complexity of our fully numerical models can be encapsulated by simple analytical expressions. Rates of subduction and slab dip correlate strongly with the asthenospheric pressure difference across the subducting slab. For double subduction, an additional slab gives rise to more complex mantle pressure and flow fields, and significantly extends the range of plate kinematics (e.g., convergence rate, trench migration rate) beyond those present in single slab models. Despite these additional complexities, we show that much of the dynamics of such multi-slab systems can be understood using the physics illuminated by our single slab study, and that a force-balance method can be used to relate intra-plate stress to viscous pressure in the asthenosphere and coupling forces at plate boundaries. This method has promise for rapid modeling of large systems of subduction zones on a global scale.
The Pulsed Cylindrical Magnetron for Deposition
Korenev, Sergey
2012-10-01
The magnetron sputtering deposition of films and coatings broadly uses in microelectronics, material science, environmental applications and etc. The rate of target evaporation and time for deposition of films and coatings depends on magnetic field. These parameters link with efficiency of gas molecules ionization by electrons. The cylindrical magnetrons use for deposition of films and coatings on inside of pipes for different protective films and coatings in oil, chemical, environmental applications. The classical forming of magnetic field by permanent magnets or coils for big and long cylindrical magnetrons is complicated. The new concept of pulsed cylindrical magnetron for high rate deposition of films and coating for big and long pipes is presented in this paper. The proposed cylindrical magnetron has azimuthally pulsed high magnetic field, which allows forming the high ionized plasma and receiving high rate of evaporation material of target (central electrode). The structure of proposed pulsed cylindrical magnetron sputtering system is given. The main requirements to deposition system are presented. The preliminary data for forming of plasma and deposition of Ta films and coatings on the metal pipers are discussed. The comparison of classical and proposed cylindrical magnetrons is given. The analysis of potential applications is considered.
Intensity and absorbed-power distribution in a cylindrical solar-pumped dye laser
Williams, M. D.
1984-01-01
The internal intensity and absorbed-power distribution of a simplified hypothetical dye laser of cylindrical geometry is calculated. Total absorbed power is also calculated and compared with laboratory measurements of lasing-threshold energy deposition in a dye cell to determine the suitability of solar radiation as a pump source or, alternatively, what modifications, if any, are necessary to the hypothetical system for solar pumping.
Approximate first collision probabilities for neutrons in cylindrical and cluster lattices
International Nuclear Information System (INIS)
Robinson, G.S.
1979-05-01
Methods for calculating approximate first collision probabilities for neutrons in cylindrical and cluster lattices are presented and compared with numerical solution methods. The methods differ from those of other authors in the inclusion of anisotropic boundary conditions for both geometries. The methods, which are fast enough for routine use in multigroup and resonance subgroup calculations, have been coded in FORTRAN and included in modules of the AUS scheme for reactor neutronics calculations
Infinite slab-shield dose calculations
International Nuclear Information System (INIS)
Russell, G.J.
1989-01-01
I calculated neutron and gamma-ray equivalent doses leaking through a variety of infinite (laminate) slab-shields. In the shield computations, I used, as the incident neutron spectrum, the leakage spectrum (<20 MeV) calculated for the LANSCE tungsten production target at 90 degree to the target axis. The shield thickness was fixed at 60 cm. The results of the shield calculations show a minimum in the total leakage equivalent dose if the shield is 40-45 cm of iron followed by 20-15 cm of borated (5% B) polyethylene. High-performance shields can be attained by using multiple laminations. The calculated dose at the shield surface is very dependent on shield material. 4 refs., 4 figs., 1 tab
LASERS: A cryogenic slab CO laser
Ionin, Andrei A.; Kozlov, A. Yu; Seleznev, L. V.; Sinitsyn, D. V.
2009-03-01
A compact capacitive transverse RF-discharge-pumped slab CO laser with cryogenically cooled electrodes, which operates both in the cw and repetitively pulsed regimes, is fabricated. The laser operation is studied in the free running multifrequency regime at the vibrational - rotational transitions of the fundamental (V + 1 → V) vibrational bands of the CO molecule in the spectral region from 5.1 to 5.4 μm. Optimal operation conditions (gas mixture composition and pressure, RF pump parameters) are determined. It is shown that only gas mixtures with a high content of oxygen (up to 20% with respect to the concentration of CO molecules) can be used as an active medium of this laser. It is demonstrated that repetitively pulsed pumping is more efficient compared to cw pumping. In this case, quasi-cw lasing regime can be obtained. The maximum average output power of ~12 W was obtained for this laser operating on fundamental bands and its efficiency achieved ~14 %. The frequency-selective operation regime of the slab RF-discharge-pumped CO laser was realised at ~ 100 laser lines in the spectral region from 5.0 to 6.5 μm with the average output power of up to several tens of milliwatts in each line. Lasing at the transitions of the first vibrational overtone (V + 2 → V) of the CO molecule is obtained in the spectral region from 2.5 to 3.9 μm. The average output power of the overtone laser achieved 0.3 W. All the results were obtained without the forced gas mixture exchange in the discharge chamber. Under fixed experimental conditions, repetitively pulsed lasing (with fluctuations of the output characteristics no more than ±10 %) was stable for more than an hour.
Direct Simulation of Extinction in a Slab of Spherical Particles
Mackowski, D.W.; Mishchenko, Michael I.
2013-01-01
The exact multiple sphere superposition method is used to calculate the coherent and incoherent contributions to the ensemble-averaged electric field amplitude and Poynting vector in systems of randomly positioned nonabsorbing spherical particles. The target systems consist of cylindrical volumes, with radius several times larger than length, containing spheres with positional configurations generated by a Monte Carlo sampling method. Spatially dependent values for coherent electric field amplitude, coherent energy flux, and diffuse energy flux, are calculated by averaging of exact local field and flux values over multiple configurations and over spatially independent directions for fixed target geometry, sphere properties, and sphere volume fraction. Our results reveal exponential attenuation of the coherent field and the coherent energy flux inside the particulate layer and thereby further corroborate the general methodology of the microphysical radiative transfer theory. An effective medium model based on plane wave transmission and reflection by a plane layer is used to model the dependence of the coherent electric field on particle packing density. The effective attenuation coefficient of the random medium, computed from the direct simulations, is found to agree closely with effective medium theories and with measurements. In addition, the simulation results reveal the presence of a counter-propagating component to the coherent field, which arises due to the internal reflection of the main coherent field component by the target boundary. The characteristics of the diffuse flux are compared to, and found to be consistent with, a model based on the diffusion approximation of the radiative transfer theory.
Geometry essentials for dummies
Ryan, Mark
2011-01-01
Just the critical concepts you need to score high in geometry This practical, friendly guide focuses on critical concepts taught in a typical geometry course, from the properties of triangles, parallelograms, circles, and cylinders, to the skills and strategies you need to write geometry proofs. Geometry Essentials For Dummies is perfect for cramming or doing homework, or as a reference for parents helping kids study for exams. Get down to the basics - get a handle on the basics of geometry, from lines, segments, and angles, to vertices, altitudes, and diagonals Conque
Fourier mode analysis of slab-geometry transport iterations in spatially periodic media
International Nuclear Information System (INIS)
Larsen, E W; Zika, M R
1999-01-01
We describe a Fourier analysis of the diffusion-synthetic acceleration (DSA) and transport-synthetic acceleration (TSA) iteration schemes for a spatially periodic, but otherwise arbitrarily heterogeneous, medium. Both DSA and TSA converge more slowly in a heterogeneous medium than in a homogeneous medium composed of the volume-averaged scattering ratio. In the limit of a homogeneous medium, our heterogeneous analysis contains eigenvalues of multiplicity two at ''resonant'' wave numbers. In the presence of material heterogeneities, error modes corresponding to these resonant wave numbers are ''excited'' more than other error modes. For DSA and TSA, the iteration spectral radius may occur at these resonant wave numbers, in which case the material heterogeneities most strongly affect iterative performance
International Nuclear Information System (INIS)
Edery, D.
1983-11-01
The reduced system of the non linear resistive MHD equations is used in the 2-D one helicity approximation in the numerical computations of stationary tearing modes. The critical magnetic Raynolds number S (S=tausub(r)/tausub(H) where tausub(R) and tausub(H) are respectively the characteristic resistive and hydro magnetic times) and the corresponding linear solution are computed as a starting approximation for the full non linear equations. These equations are then treated numerically by an iterative procedure which is shown to be rapidly convergent. A numerical application is given in the last part of this paper
International Nuclear Information System (INIS)
Rosa, M.; Warsa, J. S.; Chang, J. H.
2006-01-01
A Fourier analysis is conducted for the discrete-ordinates (SN) approximation of the neutron transport problem solved with Richardson iteration (Source Iteration) and Richardson iteration preconditioned with Transport Synthetic Acceleration (TSA), using the Parallel Block-Jacobi (PBJ) algorithm. Both 'traditional' TSA (TTSA) and a 'modified' TSA (MTSA), in which only the scattering in the low order equations is reduced by some non-negative factor β and < 1, are considered. The results for the un-accelerated algorithm show that convergence of the PBJ algorithm can degrade. The PBJ algorithm with TTSA can be effective provided the β parameter is properly tuned for a given scattering ratio c, but is potentially unstable. Compared to TTSA, MTSA is less sensitive to the choice of β, more effective for the same computational effort (c'), and it is unconditionally stable. (authors)
Arithmetic noncommutative geometry
Marcolli, Matilde
2005-01-01
Arithmetic noncommutative geometry denotes the use of ideas and tools from the field of noncommutative geometry, to address questions and reinterpret in a new perspective results and constructions from number theory and arithmetic algebraic geometry. This general philosophy is applied to the geometry and arithmetic of modular curves and to the fibers at archimedean places of arithmetic surfaces and varieties. The main reason why noncommutative geometry can be expected to say something about topics of arithmetic interest lies in the fact that it provides the right framework in which the tools of geometry continue to make sense on spaces that are very singular and apparently very far from the world of algebraic varieties. This provides a way of refining the boundary structure of certain classes of spaces that arise in the context of arithmetic geometry, such as moduli spaces (of which modular curves are the simplest case) or arithmetic varieties (completed by suitable "fibers at infinity"), by adding boundaries...
Effect of kenaf fiber in reinforced concrete slab
Syed Mohsin, S. M.; Baarimah, A. O.; Jokhio, G. A.
2018-04-01
The effect of kenaf fibers in reinforced concrete slab with different thickness is discusses and presented in this paper. Kenaf fiber is a type of natural fiber and is added in the reinforced concrete slab to improve the structure strength and ductility. For this study, three types of mixtures were prepared with fiber volume fraction of 0%, 1% and 2%, respectively. The design compressive strength considered was 20 MPa. Six cubes were prepared to be tested at 7th and 28th day. A total of six reinforced concrete slab with two variances of thickness were also prepared and tested under four-point bending test. The differences in the thickness is to study the potential of kenaf fiber to serve as part of shear reinforcement in reinforced concrete slab that was design to fail in shear. It was observed that, addition of kenaf fiber in reinforced concrete slab improves the flexural strength and ductility of the reinforced concrete slab. In the slab with reduction in thickness, the mode of failure change from brittle to ductile with the inclusion of kenaf fiber.
Study of skin model and geometry effects on thermal performance of thermal protective fabrics
Zhu, Fanglong; Ma, Suqin; Zhang, Weiyuan
2008-05-01
Thermal protective clothing has steadily improved over the years as new materials and improved designs have reached the market. A significant method that has brought these improvements to the fire service is the NFPA 1971 standard on structural fire fighters’ protective clothing. However, this testing often neglects the effects of cylindrical geometry on heat transmission in flame resistant fabrics. This paper deals with methods to develop cylindrical geometry testing apparatus incorporating novel skin bioheat transfer model to test flame resistant fabrics used in firefighting. Results show that fabrics which shrink during the test can have reduced thermal protective performance compared with the qualities measured with a planar geometry tester. Results of temperature differences between skin simulant sensors of planar and cylindrical tester are also compared. This test method provides a new technique to accurately and precisely characterize the thermal performance of thermal protective fabrics.
Requalification analysis of a circular composite slab for seismic load
International Nuclear Information System (INIS)
Srinivasan, M.G.; Kot, C.A.
1993-01-01
The circular roof slab of an existing facility was analyzed to requalify the structure for supporting a significant seismic load that it was not originally designed for. The slab has a clear span of 66 ft and consists of a 48 in. thick reinforced concrete member and a steel liner plate. Besides a number of smaller penetrations, the slab contains two significant cutouts. The dominant load for the slab came from seismic excitation. It was characterized by a response spectrum with a peak spectral acceleration of 0.72 g in the vertical direction. The first part of the analysis showed that the nature of attachment between the liner plate and the reinforced concrete (RC) slab would justify assuming composite action between the two. A finite clement analysis, with the ANSYS code, was made to investigate the region surrounding the openings. As the reinforcement in the slab was quite inhomogeneous, it was necessary to determine the stresses in other areas of the slab also. These were obtained with closed form expressions. Finally it is shown that the strength design provisions of the Code Requirements for Nuclear Safety Related Concrete Structures were met by the reinforced concrete slab and the allowable stress provisions of the American National Standard for safety related steel structures in nuclear facilities were met by the liner plate. The composite action between the RC slab and the liner plate provides for the additional strength required to support the enhanced seismic load. The issues that complicated the analysis of this nontypical structure, i.e., composite action and nonlinear stiffness of RC sections, are discussed. It was possible to circumvent the difficulties by making conservative and simplifying assumptions. If design codes incorporate guidelines on practical methods for dynamic analysis of RC structures, some of the unneeded conservatism could be eliminated in future designs
Buoyancy-driven mixing of fluids in a confined geometry
International Nuclear Information System (INIS)
Hallez, Y.
2007-12-01
The present work based on Direct Numerical Simulations is devoted to the study of mixing between two miscible fluids of different densities. The movement of these fluids is induced by buoyancy. Three geometries are considered: a cylindrical tube, a square channel and a plane two-dimensional flow. For cylindrical tubes, the results of numerical simulations fully confirm previous experimental findings by Seon et al., especially regarding the existence of three different flow regimes, depending on the tilt angle. The comparison of the various geometries shows that tridimensional flows in tubes or channels are similar, whereas the two-dimensional model fails to give reliable information about real 3D flows, either from a quantitative point of view or for a phenomenological understanding. A peculiar attention is put on a joint analysis of the concentration and vorticity fields and allows us to explain several subtle aspects of the mixing dynamics. (author)
Rayleigh-Taylor instability in accelerated elastic-solid slabs
Piriz, S. A.; Piriz, A. R.; Tahir, N. A.
2017-12-01
We develop the linear theory for the asymptotic growth of the incompressible Rayleigh-Taylor instability of an accelerated solid slab of density ρ2, shear modulus G , and thickness h , placed over a semi-infinite ideal fluid of density ρ110.1007/s000330050121] to arbitrary values of AT and unveil the singular feature of an instability threshold below which the slab is stable for any perturbation wavelength. As a consequence, an accelerated elastic-solid slab is stable if ρ2g h /G ≤2 (1 -AT) /AT .
Interaction of an ion bunch with a plasma slab
Energy Technology Data Exchange (ETDEWEB)
Krasovitskiy, V. B., E-mail: krasovit@mail.ru [Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation); Turikov, V. A. [Peoples’ Friendship University of Russia (Russian Federation)
2016-11-15
Charge neutralization of a short ion bunch passing through a plasma slab is studied by means of numerical simulation. It is shown that a fraction of plasma electrons are trapped by the bunch under the action of the collective charge separation field. The accelerated electrons generated in this process excite beam−plasma instability, thereby violating the trapping conditions. The process of electron trapping is also strongly affected by the high-frequency electric field caused by plasma oscillations at the slab boundaries. It is examined how the degree of charge neutralization depends on the parameters of the bunch and plasma slab.
Light-assisted templated self assembly using photonic crystal slabs.
Mejia, Camilo A; Dutt, Avik; Povinelli, Michelle L
2011-06-06
We explore a technique which we term light-assisted templated self-assembly. We calculate the optical forces on colloidal particles over a photonic crystal slab. We show that exciting a guided resonance mode of the slab yields a resonantly-enhanced, attractive optical force. We calculate the lateral optical forces above the slab and predict that stably trapped periodic patterns of particles are dependent on wavelength and polarization. Tuning the wavelength or polarization of the light source may thus allow the formation and reconfiguration of patterns. We expect that this technique may be used to design all-optically reconfigurable photonic devices.
Novel biometric flow slab design for improvement of PEMFC performance
Energy Technology Data Exchange (ETDEWEB)
Wang, Chin-Tsan; Hu, Yuh-Chung; Zheng, Pei-Lun [Department of Mechanical and Electro-Mechanical Engineering, Center of Green Technology, National I Lan University, I Lan 26047 (China)
2010-04-15
Designing a better flow slab is important to cell performance because of its significant influence on the total pressure drop and flow uniformity. Two novel biometric flow slabs, BFF1 and BFF2, which are addressed in this study, are believed to enhance the capability of oxygen transportation and promote the liquid water removal. Hence, its possession of a higher flow uniformity and lower pressure drop would produce a better power performance than the serpentine and parallel flow. These findings with respect to the design of biometric flow slab could be useful to promote the cell performance of PEMFC, and could even be expanded to other cell types. (author)
Dynamic Eigenvalue Problem of Concrete Slab Road Surface
Pawlak, Urszula; Szczecina, Michał
2017-10-01
The paper presents an analysis of the dynamic eigenvalue problem of concrete slab road surface. A sample concrete slab was modelled using Autodesk Robot Structural Analysis software and calculated with Finite Element Method. The slab was set on a one-parameter elastic subsoil, for which the modulus of elasticity was separately calculated. The eigen frequencies and eigenvectors (as maximal vertical nodal displacements) were presented. On the basis of the results of calculations, some basic recommendations for designers of concrete road surfaces were offered.
Bárány, Imre; Vilcu, Costin
2016-01-01
This volume presents easy-to-understand yet surprising properties obtained using topological, geometric and graph theoretic tools in the areas covered by the Geometry Conference that took place in Mulhouse, France from September 7–11, 2014 in honour of Tudor Zamfirescu on the occasion of his 70th anniversary. The contributions address subjects in convexity and discrete geometry, in distance geometry or with geometrical flavor in combinatorics, graph theory or non-linear analysis. Written by top experts, these papers highlight the close connections between these fields, as well as ties to other domains of geometry and their reciprocal influence. They offer an overview on recent developments in geometry and its border with discrete mathematics, and provide answers to several open questions. The volume addresses a large audience in mathematics, including researchers and graduate students interested in geometry and geometrical problems.
Czech Academy of Sciences Publication Activity Database
Mikula, Pavol; Vrána, Miroslav; Šaroun, Jan; Davydov, Vadim; Em, V.; Seong, B. S.
2012-01-01
Roč. 45, č. 1 (2012), s. 98-105 ISSN 0021-8898 R&D Projects: GA ČR GAP204/10/0654 Institutional research plan: CEZ:AV0Z10480505 Keywords : RESIDUAL STRAIN-STRESS INSTRUMENT * MULTIPLE BRAGG-REFLECTIONS * SINGLE-CRYSTAL Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.343, year: 2012
IVA2 verification: Expansion phase experiment in SNR geometry
International Nuclear Information System (INIS)
Kolev, N.I.
1987-09-01
Using the IVA2/005 computer code the SNR model explosion experiment SGI-09-1 was numerically simulated. The experiment consists of high pressure gas injection into a low pressure liquid pool with a free surface in a cylindrical geometry with internals. Bubble formation and pressure history as a function of time was predicted and compared with the experimental observation. A good agreement between theory and experiment was obtained. Numerical diffusion and its influence on the results are discussed. (orig.) [de
Algorithms in Algebraic Geometry
Dickenstein, Alicia; Sommese, Andrew J
2008-01-01
In the last decade, there has been a burgeoning of activity in the design and implementation of algorithms for algebraic geometric computation. Some of these algorithms were originally designed for abstract algebraic geometry, but now are of interest for use in applications and some of these algorithms were originally designed for applications, but now are of interest for use in abstract algebraic geometry. The workshop on Algorithms in Algebraic Geometry that was held in the framework of the IMA Annual Program Year in Applications of Algebraic Geometry by the Institute for Mathematics and Its
O'Leary, Michael
2010-01-01
Guides readers through the development of geometry and basic proof writing using a historical approach to the topic. In an effort to fully appreciate the logic and structure of geometric proofs, Revolutions of Geometry places proofs into the context of geometry's history, helping readers to understand that proof writing is crucial to the job of a mathematician. Written for students and educators of mathematics alike, the book guides readers through the rich history and influential works, from ancient times to the present, behind the development of geometry. As a result, readers are successfull
Fundamental concepts of geometry
Meserve, Bruce E
1983-01-01
Demonstrates relationships between different types of geometry. Provides excellent overview of the foundations and historical evolution of geometrical concepts. Exercises (no solutions). Includes 98 illustrations.
Developments in special geometry
International Nuclear Information System (INIS)
Mohaupt, Thomas; Vaughan, Owen
2012-01-01
We review the special geometry of N = 2 supersymmetric vector and hypermultiplets with emphasis on recent developments and applications. A new formulation of the local c-map based on the Hesse potential and special real coordinates is presented. Other recent developments include the Euclidean version of special geometry, and generalizations of special geometry to non-supersymmetric theories. As applications we discuss the proof that the local r-map and c-map preserve geodesic completeness, and the construction of four- and five-dimensional static solutions through dimensional reduction over time. The shared features of the real, complex and quaternionic version of special geometry are stressed throughout.
Energy Technology Data Exchange (ETDEWEB)
Hallez, Y
2007-12-15
The present work based on Direct Numerical Simulations is devoted to the study of mixing between two miscible fluids of different densities. The movement of these fluids is induced by buoyancy. Three geometries are considered: a cylindrical tube, a square channel and a plane two-dimensional flow. For cylindrical tubes, the results of numerical simulations fully confirm previous experimental findings by Seon et al., especially regarding the existence of three different flow regimes, depending on the tilt angle. The comparison of the various geometries shows that tridimensional flows in tubes or channels are similar, whereas the two-dimensional model fails to give reliable information about real 3D flows, either from a quantitative point of view or for a phenomenological understanding. A peculiar attention is put on a joint analysis of the concentration and vorticity fields and allows us to explain several subtle aspects of the mixing dynamics. (author)
High precision electrostatic potential calculations for cylindrically symmetric lenses
International Nuclear Information System (INIS)
Edwards, David Jr.
2007-01-01
A method is developed for a potential calculation within cylindrically symmetric electrostatic lenses using mesh relaxation techniques, and it is capable of considerably higher accuracies than currently available. The method involves (i) creating very high order algorithms (orders of 6, 8, and 10) for determining the potentials at points in the net using surrounding point values, (ii) eliminating the effect of the large errors caused by singular points, and (iii) reducing gradients in the high gradient regions of the geometry, thereby allowing the algorithms used in these regions to achieve greater precisions--(ii) and (iii) achieved by the use of telescopic multiregions. In addition, an algorithm for points one unit from a metal surface is developed, allowing general mesh point algorithms to be used in these situations, thereby taking advantage of the enhanced precision of the latter. A maximum error function dependent on a sixth order gradient of the potential is defined. With this the single point algorithmic errors are able to be viewed over the entire net. Finally, it is demonstrated that by utilizing the above concepts and procedures, the potential of a point in a reasonably high gradient region of a test geometry can realize a precision of less than 10 -10
Photonic slab heterostructures based on opals
Palacios-Lidon, Elisa; Galisteo-Lopez, Juan F.; Juarez, Beatriz H.; Lopez, Cefe
2004-09-01
In this paper the fabrication of photonic slab heterostructures based on artificial opals is presented. The innovated method combines high-quality thin-films growing of opals and silica infiltration by Chemical Vapor Deposition through a multi-step process. By varying structure parameters, such as lattice constant, sample thickness or refractive index, different heterostructures have been obtained. The optical study of these systems, carried out by reflectance and transmittance measurements, shows that the prepared samples are of high quality further confirmed by Scanning Electron Microscopy micrographs. The proposed novel method for sample preparation allows a high control of the involved structure parameters, giving the possibility of tunning their photonic behavior. Special attention in the optical response of these materials has been addressed to the study of planar defects embedded in opals, due to their importance in different photonic fields and future technological applications. Reflectance and transmission measurements show a sharp resonance due to localized states associated with the presence of planar defects. A detailed study of the defect mode position and its dependance on defect thickness and on the surrounding photonic crystal is presented as well as evidence showing the scalability of the problem. Finally, it is also concluded that the proposed method is cheap and versatile allowing the preparation of opal-based complex structures.
Hybrid Heat Capacity - Moving Slab Laser Concept
International Nuclear Information System (INIS)
Stappaerts, E A
2002-01-01
A hybrid configuration of a heat capacity laser (HCL) and a moving slab laser (MSL) has been studied. Multiple volumes of solid-state laser material are sequentially diode-pumped and their energy extracted. When a volume reaches a maximum temperature after a ''sub-magazine depth'', it is moved out of the pumping region into a cooling region, and a new volume is introduced. The total magazine depth equals the submagazine depth times the number of volumes. The design parameters are chosen to provide high duty factor operation, resulting in effective use of the diode arrays. The concept significantly reduces diode array cost over conventional heat capacity lasers, and it is considered enabling for many potential applications. A conceptual design study of the hybrid configuration has been carried out. Three concepts were evaluated using CAD tools. The concepts are described and their relative merits discussed. Because of reduced disk size and diode cost, the hybrid concept may allow scaling to average powers on the order of 0.5 MW/module
Evaluation of precast concrete slabs using a heavy vehicle simulator
CSIR Research Space (South Africa)
Kohler, E
2008-10-01
Full Text Available Precast slabs are considered an attractive pavement option for rehabilitation or reconstruction cases where traffic closures of less than eight hours are required. Benefits include long life expectancy of concrete cast in factory...
Novel variational approach for analysis of photonic crystal slabs
International Nuclear Information System (INIS)
Aram, Mohammad Hasan; Khorasani, Sina
2015-01-01
We propose a new method, based on variational principle, for the analysis of photonic crystal (PC) slabs. Most of the methods used today treat PC slabs as three-dimensional (3D) crystal, and this makes these methods very time and/or memory consuming. In our proposed method, we use the Bloch theorem to expand the field on infinite plane waves, whose amplitudes depend on the component perpendicular to the slab surface. By approximating these amplitudes with appropriate functions, we can find modes of PC slabs almost as fast as we can find modes of two-dimensional crystals. In addition to this advantage, we can also calculate radiation modes with this method, which is not feasible with the 3D plane wave expansion method. (paper)
Fire resistance of extruded hollow-core slabs
DEFF Research Database (Denmark)
Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa
2017-01-01
to the structural codes with data derived from a standard fire test and from a thorough examination of the comprehensive test documentation available on fire exposed hollow-core slabs. Findings – Mechanisms for loss of load-bearing capacity are clarified, and evidence of the fire resistance is found. Originality......Purpose – Prefabricated extruded hollow-core slabs are preferred building components for floor structures in several countries. It is therefore important to be able to document the fire resistance of these slabs proving fulfilment of standard fire resistance requirements of 60 and 120 min found...... in most national building regulations. The paper aims to present a detailed analysis of the mechanisms responsible for the loss of loadbearing capacity of hollow-core slabs when exposed to fire. Design/methodology/approach – Furthermore, it compares theoretica calculation and assessment according...
General analysis of slab lasers using geometrical optics.
Chung, Te-yuan; Bass, Michael
2007-02-01
A thorough and general geometrical optics analysis of a slab-shaped laser gain medium is presented. The length and thickness ratio is critical if one is to achieve the maximum utilization of absorbed pump power by the laser light in such a medium; e.g., the fill factor inside the slab is to be maximized. We point out that the conditions for a fill factor equal to 1, laser light entering and exiting parallel to the length of the slab, and Brewster angle incidence on the entrance and exit faces cannot all be satisfied at the same time. Deformed slabs are also studied. Deformation along the width direction of the largest surfaces is shown to significantly reduce the fill factor that is possible.
Radon exhalation study from cement, cement slabs and concrete slabs with variation in fly ash
International Nuclear Information System (INIS)
Sharma, Nisha; Singh, Jaspal
2012-01-01
Fly ash is a waste product from coal-fired power plants. Fly ash has become a subject of world-wide interest in recent years because of its diverse uses, e.g. in the manufacture of concrete for building purposes, for the filling of underground cavities, or as a component of building material. The fly ash may contain enhanced levels of the natural radionuclides in the uranium and thorium series and by using the fly ash in building materials, the radiation levels in houses may thus be technologically enhanced. Because of its relatively high radionuclide contents (including 226 Ra), fly ash may, however, present a potential hazard to the population through its radon emanation, which would be highly undesirable. Since fly ash is frequently used as a building material, the idea of the experiment was to mix fly ash in different proportions in the cement in the powder form, cemented slabs and concrete slabs to study the combined behaviors. Alpha sensitive LR-115 type II plastic track detector, commonly known as Solid State Nuclear Track Detectors (SSNTDs), were used to measure the radon concentration. The alpha particles emitted from the radon causes the radiation damaged tracks. The chemical etching in NaOH at 60°C for about 90 minutes was done to reveal these latent tracks, which were then scanned and counted by an optical microscope of suitable magnification. By calculating the track density of registered tracks, the radon concentrations were determined. In case of cement in the powder form and in cemented slab, starting from the pure cement, fly ash was added up to 70% by weight. In this case the radon exhalation rate has increased by addition of fly ash in the cement and in case of concrete slabs by the addition of fly ash in the cement the radon exhalation increases up to 60% and then decreases. Therefore, on the basis of our investigations we concluded that in general radon exhalation rate increases with the addition of fly ash. (author)
Forced vibrations of rotating circular cylindrical shells
International Nuclear Information System (INIS)
Igawa, Hirotaka; Maruyama, Yoshiyuki; Endo, Mitsuru
1995-01-01
Forced vibrations of rotating circular cylindrical shells are investigated. Basic equations, including the effect of initial stress due to rotation, are formulated by the finite-element method. The characteristic relations for finite elements are derived from the energy principle by considering the finite strain. The equations of motion can be separated into quasi-static and dynamic ones, i.e., the equations in the steady rotating state and those in the vibration state. Radial concentrated impulses are considered as the external dynamic force. The transient responses of circular cylindrical shells are numerically calculated under various boundary conditions and rotating speeds. (author)
Scattering of spermatozoa off cylindrical pillars
Bukatin, Anton; Lushi, Enkeleida; Kantsler, Vasily
2017-11-01
The motion of micro-swimmers in structured environments, even though crucial in processes such as in vivo and in vitro egg fertilization, is still not completely understood. We combine microfluidic experiments with mathematical modeling of 3D swimming near convex surfaces to quantify the dynamics of individual sperm cells in the proximity of cylindrical pillars. Our results show that the hydrodynamic and contact forces that account for the shape asymmetry and flagellar motion, are crucial in correctly describing the dynamics observed in the experiments. Last, we discuss how the size of the cylindrical obstacles determines whether the swimmers scatter off or get trapped circling the pillar.
Micromagnetic simulations of cylindrical magnetic nanowires
Ivanov, Yurii P.
2015-05-27
This chapter reviews micromagnetic simulations of cylindrical magnetic nanowires and their ordered arrays. It starts with a description of the theoretical background of micromagnetism. The chapter discusses main magnetization reversal modes, domain wall types, and state diagrams in cylindrical nanowires of different types and sizes. The results of the hysteresis process in individual nanowires and nanowire arrays also are presented. Modeling results are compared with experimental ones. The chapter also discusses future trends in nanowire applications in relation to simulations, such as current-driven dynamics, spintronics, and spincaloritronics. The main micromagnetic programs are presented and discussed, together with the corresponding links.
Cylindrical concave body of composite fibrous material
International Nuclear Information System (INIS)
1979-01-01
The invention is concerned with a cylindrical concave body of compound fibrous material which is intended to be exposed to high rotation speeds around its own longitudinal axis. The concave body in question has at least one layer of fibrils that are interwoven and enclose an identical angle with the longitudinal axis of the concave body in both directions. The concave body in question also has at least a second layer of fibrils that run in the direction of the circumference and are fitted radially to the outside. The cylindrical concave body of the invention is particularly well suited for application as a rotor tube in a gas ultra-centrifuge
Cylindrical pressure vessel constructed of several layers
International Nuclear Information System (INIS)
Yamauchi, Takeshi.
1976-01-01
For a cylindrical pressure vessel constructed of several layers whose jacket has at least one circumferential weld joining the individual layers, it is proposed to provide this at least at the first bending line turning point (counting from the weld between the jacket and vessel floor), which the sinusoidally shaped jacket has. The section of the jacket extending in between should be made as a full wall section. The proposal is based on calculations of the bending stiffness of cylindrical jackets, which could not yet be confirmed for jackets having several layers. (UWI) [de
Magnetic guns with cylindrical permanent magnets
DEFF Research Database (Denmark)
Vokoun, David; Beleggia, Marco; Heller, Luděk
2012-01-01
The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...... of the magnetostatic interaction energy. For comparison, the forces involved are also calculated numerically using finite elements methods. Based on the conservation of the magnetostatic and kinetic energies, the exit and asymptotic velocities are determined. The derived formulas can be used to optimize the generated...... forces and motion of the inner cylindrical magnet....
Calculation of shear strength of prestressed hollow core slabs by use of plastic theory
DEFF Research Database (Denmark)
Hoang, Linh Cao; Jørgensen, H.G.; Nielsen, Mogens Peter
2014-01-01
Th is paper deals with calculations of the shear capacity of precast, prestressed hollow core slabs. Such slabs are often used as floor systems in building structures. A common way to produce hollow core slabs is to use the extrusion technique where long strips of slabs are extruded and thereafter...
Optimising the Slab Yard Planning and Crane Scheduling Problem using a two-stage heuristic
DEFF Research Database (Denmark)
Hansen, Anders Dohn; Clausen, Jens
2010-01-01
In this paper, we present the Slab Yard Planning and Crane Scheduling Problem. The problem has its origin in steel production facilities with a large throughput. A slab yard is used as a buffer for slabs that are needed in the upcoming production. Slabs are transported by cranes and the problem...
Performance and damages of R.C. slabs in fire
DEFF Research Database (Denmark)
Giuliani, Luisa; Gentili, Filippo
2015-01-01
Contrary to a common misconception, concrete structures are particularly vulnerable to fire, as witnesses by several cases of fire-induced collapses of buildings with a primary concrete structural system. Even when no collapse occurs, concrete elements are permanently damaged by the fire and may...... on the vulnerability of the slab to the fire action and can be used for optimizing the design on the basis of the required class of resistance or for choosing between different slab alternatives....
Self-consistent solution for a collisionless plasma slab in motion across a magnetic field
International Nuclear Information System (INIS)
Echim, Marius M.; Lemaire, Joseph F.; Roth, Michel
2005-01-01
The problem of the dynamics of a plasma slab moving across a magnetic field is treated in the framework of the kinetic theory. A velocity distribution function (VDF) is found for each plasma species, electrons and protons, in terms of the constants of motion defined by the geometry of the problem. The zero- and first-order moments of the VDF are introduced into the right-hand side term of Maxwell's equations to compute the electric and magnetic vector potentials and corresponding fields. The solutions are found numerically. We obtain a region of plasma convection--the slab proper--where the plasma moves with a uniform velocity, V x =V 0 =(ExB/B 2 ) x . At the core margins two plasma 'wings' are formed, each being the result of a pair of interpenetrated boundary layers with different transition lengths. Inside these wings, the plasma velocity is not uniform, V x ≠(ExB/B 2 ) x . It decreases from the maximum value obtained in the core to a minimum value in the central region of the wings where a flow reversal is found with the plasma convecting in the opposite direction to the core motion. There is also an asymmetry of the velocity gradient at the borders of the core, which results in a corresponding asymmetry in the thickness of the wings. Furthermore, it is found that the reversed plasma flow in the thinner wing is larger than that in the broader wing. For a fixed direction of the magnetic field the two plasma wings interchange position with respect to the center of the slab when the plasma bulk velocity reverses sign
Geometry of multihadron production
Energy Technology Data Exchange (ETDEWEB)
Bjorken, J.D.
1994-10-01
This summary talk only reviews a small sample of topics featured at this symposium: Introduction; The Geometry and Geography of Phase space; Space-Time Geometry and HBT; Multiplicities, Intermittency, Correlations; Disoriented Chiral Condensate; Deep Inelastic Scattering at HERA; and Other Contributions.
1996-01-01
Designs and Finite Geometries brings together in one place important contributions and up-to-date research results in this important area of mathematics. Designs and Finite Geometries serves as an excellent reference, providing insight into some of the most important research issues in the field.
Geometry of multihadron production
International Nuclear Information System (INIS)
Bjorken, J.D.
1994-10-01
This summary talk only reviews a small sample of topics featured at this symposium: Introduction; The Geometry and Geography of Phase space; Space-Time Geometry and HBT; Multiplicities, Intermittency, Correlations; Disoriented Chiral Condensate; Deep Inelastic Scattering at HERA; and Other Contributions
Morris, Barbara H.
2004-01-01
This article describes a geometry project that used the beauty of stained-glass-window designs to teach middle school students about geometric figures and concepts. Three honors prealgebra teachers and a middle school mathematics gifted intervention specialist created a geometry project that covered the curriculum and also assessed students'…
Recent progress in high-power slab lasers in Japan
International Nuclear Information System (INIS)
Fujii, Y.
1988-01-01
Recently, many solid-state lasers have been widely employed in Japanese industries, especially in the electronics industries for precise and reliable processing. To expand the use of solid-state lasers and to achieve higher processing speed, the authors are developing slab lasers of high power, high repetition rate, and high beam quality. Metal processing systems with optical fibers for large and complex 3-D work, multiwork station systems linked to only one laser with optical fibers, and compact x-ray sources for lithography are promising areas for such lasers. Surnitomo Metal Mining is growing Nd:GGG and Nd:YAG crystals 60 mm in diameter and 200 mm long. From 2 at.% Nd-doped GGG crystals without central core regions. The authors obtained two slab materials with dimensions of 35 X 9 X 192 and 55 X 15 X 213 mm/sup 3/. By using the smaller slab, they constructed a slab laser and obtained 370-W laser output power at 24-kW lamp input power and 10-pps repetition rate. Now they are constructing a 1-kW slab laser using the other larger size slab
Strengthening of RC bridge slabs using CFRP sheets
Directory of Open Access Journals (Sweden)
Fahmy A. Fathelbab
2014-12-01
Full Text Available Many old structures became structurally insufficient to carry the new loading conditions requirements. Moreover, they suffer from structural degradation, reinforcement steel bars corrosion, bad weather conditions…etc. Many official authorities in several countries had recognized many old bridges and buildings as structurally deficient by today’s standards. Due to these reasons, structural strengthening became an essential requirement and different strengthening techniques appeared in market. Fiber Reinforced Polymer (FRP strengthening techniques established a good position among all other techniques, giving excellent structural results, low time required and moderate cost compared with the other techniques. The main purpose of this research is to study analytically the strengthening of a reinforced concrete bridge slabs due to excessive loads, using externally bonded FRP sheets technique. A commercial finite element program ANSYS was used to perform a structural linear and non-linear analysis for strengthened slab models using several schemes of FRP sheets. A parametric study was performed to evaluate analytically the effect of changing both FRP stiffness and FRP schemes in strengthening RC slabs. Comparing the results with control slab (reinforced concrete slab without strengthening it is obvious that attaching FRP sheets to the RC slab increases its capacity and enhances the ductility/toughness.
Energy Technology Data Exchange (ETDEWEB)
Grotz, Andreas
2011-10-07
In this thesis, a formulation of a Lorentzian quantum geometry based on the framework of causal fermion systems is proposed. After giving the general definition of causal fermion systems, we deduce space-time as a topological space with an underlying causal structure. Restricting attention to systems of spin dimension two, we derive the objects of our quantum geometry: the spin space, the tangent space endowed with a Lorentzian metric, connection and curvature. In order to get the correspondence to classical differential geometry, we construct examples of causal fermion systems by regularizing Dirac sea configurations in Minkowski space and on a globally hyperbolic Lorentzian manifold. When removing the regularization, the objects of our quantum geometry reduce to the common objects of spin geometry on Lorentzian manifolds, up to higher order curvature corrections.
Methods of information geometry
Amari, Shun-Ichi
2000-01-01
Information geometry provides the mathematical sciences with a new framework of analysis. It has emerged from the investigation of the natural differential geometric structure on manifolds of probability distributions, which consists of a Riemannian metric defined by the Fisher information and a one-parameter family of affine connections called the \\alpha-connections. The duality between the \\alpha-connection and the (-\\alpha)-connection together with the metric play an essential role in this geometry. This kind of duality, having emerged from manifolds of probability distributions, is ubiquitous, appearing in a variety of problems which might have no explicit relation to probability theory. Through the duality, it is possible to analyze various fundamental problems in a unified perspective. The first half of this book is devoted to a comprehensive introduction to the mathematical foundation of information geometry, including preliminaries from differential geometry, the geometry of manifolds or probability d...
International Nuclear Information System (INIS)
Grotz, Andreas
2011-01-01
In this thesis, a formulation of a Lorentzian quantum geometry based on the framework of causal fermion systems is proposed. After giving the general definition of causal fermion systems, we deduce space-time as a topological space with an underlying causal structure. Restricting attention to systems of spin dimension two, we derive the objects of our quantum geometry: the spin space, the tangent space endowed with a Lorentzian metric, connection and curvature. In order to get the correspondence to classical differential geometry, we construct examples of causal fermion systems by regularizing Dirac sea configurations in Minkowski space and on a globally hyperbolic Lorentzian manifold. When removing the regularization, the objects of our quantum geometry reduce to the common objects of spin geometry on Lorentzian manifolds, up to higher order curvature corrections.
Roller bearing geometry design
Savage, M.; Pinkston, B. H. W.
1976-01-01
A theory of kinematic stabilization of rolling cylinders is extended and applied to the design of cylindrical roller bearings. The kinematic stabilization mechanism puts a reverse skew into the rolling elements by changing the roller taper. Twelve basic bearing modification designs are identified amd modeled. Four have single transverse convex curvature in their rollers while eight have rollers which have compound transverse curvature made up of a central cylindrical band surrounded by symmetric bands with slope and transverse curvature. The bearing designs are modeled for restoring torque per unit axial displacement, contact stress capacity, and contact area including dynamic loading, misalignment sensitivity and roller proportion. Design programs are available which size the single transverse curvature roller designs for a series of roller slopes and load separations and which design the compound roller bearings for a series of slopes and transverse radii of curvature. The compound rollers are proportioned to have equal contact stresses and minimum size. Design examples are also given.
Geometry on the space of geometries
International Nuclear Information System (INIS)
Christodoulakis, T.; Zanelli, J.
1988-06-01
We discuss the geometric structure of the configuration space of pure gravity. This is an infinite dimensional manifold, M, where each point represents one spatial geometry g ij (x). The metric on M is dictated by geometrodynamics, and from it, the Christoffel symbols and Riemann tensor can be found. A ''free geometry'' tracing a geodesic on the manifold describes the time evolution of space in the strong gravity limit. In a regularization previously introduced by the authors, it is found that M does not have the same dimensionality, D, everywhere, and that D is not a scalar, although it is covariantly constant. In this regularization, it is seen that the path integral measure can be absorbed in a renormalization of the cosmological constant. (author). 19 refs
Automatic yield-line analysis of slabs using discontinuity layout optimization.
Gilbert, Matthew; He, Linwei; Smith, Colin C; Le, Canh V
2014-08-08
The yield-line method of analysis is a long established and extremely effective means of estimating the maximum load sustainable by a slab or plate. However, although numerous attempts to automate the process of directly identifying the critical pattern of yield-lines have been made over the past few decades, to date none has proved capable of reliably analysing slabs of arbitrary geometry. Here, it is demonstrated that the discontinuity layout optimization (DLO) procedure can successfully be applied to such problems. The procedure involves discretization of the problem using nodes inter-connected by potential yield-line discontinuities, with the critical layout of these then identified using linear programming. The procedure is applied to various benchmark problems, demonstrating that highly accurate solutions can be obtained, and showing that DLO provides a truly systematic means of directly and reliably automatically identifying yield-line patterns. Finally, since the critical yield-line patterns for many problems are found to be quite complex in form, a means of automatically simplifying these is presented.
The effects of heat generation and wall interaction on freezing and melting in a finite slab
International Nuclear Information System (INIS)
Cheung, F.B.; Chawla, T.C.; Pedersen, D.R.
1984-01-01
The processes of freezing and melting occurring in a heat-generating slab bounded by two semi-infinite cold walls is studied numerically. The method of collocation is employed to solve the various sets of governing equations describing the unsteady behavior of the system during different periods of time. Depending on the rate of internal heat generation and the thermal properties of the wall and the slab, several changes may take place in the system. These changes, as indicated by the transient locations of the solid-liquid interface, include transitions from freezing directly to melting, from freezing to cooling with phase change, from cooling to heating without phase change, and from heating to melting. Numerical predictions of the occurrence of these transitions, the rates of freezing and melting, and the duration of the transients are obtained as functions of several controlling dimensionless parameters of the system. Comparison is made with the case of a heat-generating sphere to further explore the effect of system geometry. (author)
The Effects of Buildability Factors on Rebar Fixing Labour Productivity of Beamless Slabs
Directory of Open Access Journals (Sweden)
Abdulaziz M Jarkas
2010-07-01
Full Text Available Buildability is an important factor affecting labour productivity. Nevertheless, a thorough search of the literature revealed a dearth of research into its effects on in situ reinforced concrete construction, especially at the activity levels. Since rebar fixing is an integral trade of this type of construction material, and beamless slabs are amongst the major encountered activities on construction sites, the objective of this research is to explore the buildability factors affecting its rebar fixing efficiency. To achieve this objective, a large volume of fixing productivity data was collected and analysed using the categorical interaction - regression method. As a result, the main and interaction effects of rebar diameter; reinforcement quantity; slab geometry; and reinforcement layer location are determined. The findings show a significant influence of these factors on the fixing operation, which can be used to provide designers and construction managers with feedback on how well the design of this activity considers the requirements of buildability, and the tangible consequences of designers‟ decisions on labour productivity
The Effects of Buildability Factors on Rebar Fixing Labour Productivity of Beamless Slabs
Directory of Open Access Journals (Sweden)
Abdulaziz M Jarkas
2010-06-01
Full Text Available Buildability is an important factor affecting labour productivity. Nevertheless, a thorough search of the literature revealed a dearth of research into its effects on in situ reinforced concrete construction, especially at the activity levels. Since rebar fixing is an integral trade of this type of construction material, and beamless slabs are amongst the major encountered activities on construction sites, the objective of this research is to explore the buildability factors affecting its rebar fixing efficiency. To achieve this objective, a large volume of fixing productivity data was collected and analysed using the categorical interaction - regression method. As a result, the main and interaction effects of rebar diameter; reinforcement quantity; slab geometry; and reinforcement layer location are determined. The findings show a significant influence of these factors on the fixing operation, which can be used to provide designers and construction managers with feedback on how well the design of this activity considers the requirements of buildability, and the tangible consequences of designers‟ decisions on labour productivity
The Effects of Buildability Factors on Rebar Fixing Labour Productivity of Beamless Slabs
Directory of Open Access Journals (Sweden)
Abdulaziz M Jarkas
2010-06-01
Full Text Available Buildability is an important factor affecting labour productivity. Nevertheless, a thorough search of the literature revealed a dearth of research into its effects on in situ reinforced concrete construction, especially at the activity levels. Since rebar fixing is an integral trade of this type of construction material, and beamless slabs are amongst the major encountered activities on construction sites, the objective of this research is to explore the buildability factors affecting its rebar fixing efficiency. To achieve this objective, a large volume of fixing productivity data was collected and analysed using the categorical interaction - regression method. As a result, the main and interaction effects of rebar diameter; reinforcement quantity; slab geometry; and reinforcement layer location are determined. The findings show a significant influence of these factors on the fixing operation, which can be used to provide designers and construction managers with feedback on how well the design of this activity considers the requirements of buildability, and the tangible consequences of designers‟ decisions on labour productivity
Gyrokinetic approach to the propagation of electromagnetic waves in nonuniform bounded plasma slabs
International Nuclear Information System (INIS)
Sauter, O.; Vaclavik, J.
1994-05-01
A new code, SEMAL, has been developed which solves the linearized Vlasov-Maxwell wave equations to all orders in Larmor radii. Arbitrary density and temperature profiles as well as nonuniform magnetic fields are considered in slab geometry. The vacuum regions adjacent to the plasma slab are limited by perfect conducting walls and contain an antenna as an excitation source. The linear response is obtained by solving the system of one first-order and two second-order integro-differential equations using a non-polluting finite element discretization. The general equations in the Fourier space, derived in a new comprehensive way, and their inverse transform, using k y =0, are described as well as the convergence and non-polluting properties of the method. We present the results concerning the influence of alpha particles on ICRF heating schemes for ITER, where we show that small alphas concentration can alter the steady-state operation envisaged with ICRF fast wave current-drive. (author) 7 figs., 3 tabs., 28 refs
Wellposedness of a cylindrical shell model
International Nuclear Information System (INIS)
McMillan, C.
1994-01-01
We consider a well-known model of a thin cylindrical shell with dissipative feedback controls on the boundary in the form of forces, shears, and moments. We show that the resulting closed loop feedback problem generates a s.c. semigroup of contractions in the energy space
Exact relativistic cylindrical solution of disordered radiation
International Nuclear Information System (INIS)
Fonseca Teixeira, A.F. da; Wolk, I.; Som, M.M.
1976-05-01
A source free disordered distribution of electromagnetic radiation is considered in Einstein' theory, and a time independent exact solution with cylindrical symmetry is obtained. The gravitation and pressure effects of the radiation alone are sufficient to give the distribution an equilibrium. A finite maximum concentration is found on the axis of symmetry, and decreases monotonically to zero outwards. Timelike and null geodesics are discussed
Shear stresses around circular cylindrical openings
Hoogenboom, P.C.J.; Van Weelden, C.; Blom, C.M.B.
2010-01-01
In this paper stress concentrations are studied around circular cylindrical openings or voids in a linear elastic continuum. The loading is such that a uniform shear stress occurs in the continuum, which is disturbed by the opening. The shear stress is in the direction of the centre axis of the
On isotropic cylindrically symmetric stellar models
International Nuclear Information System (INIS)
Nolan, Brien C; Nolan, Louise V
2004-01-01
We attempt to match the most general cylindrically symmetric vacuum spacetime with a Robertson-Walker interior. The matching conditions show that the interior must be dust filled and that the boundary must be comoving. Further, we show that the vacuum region must be polarized. Imposing the condition that there are no trapped cylinders on an initial time slice, we can apply a result of Thorne's and show that trapped cylinders never evolve. This results in a simplified line element which we prove to be incompatible with the dust interior. This result demonstrates the impossibility of the existence of an isotropic cylindrically symmetric star (or even a star which has a cylindrically symmetric portion). We investigate the problem from a different perspective by looking at the expansion scalars of invariant null geodesic congruences and, applying to the cylindrical case, the result that the product of the signs of the expansion scalars must be continuous across the boundary. The result may also be understood in relation to recent results about the impossibility of the static axially symmetric analogue of the Einstein-Straus model
A strong focussing cylindrical electrostatic quadrupole
International Nuclear Information System (INIS)
Sheng Yaochang
1986-01-01
The construction and performance of small cylindrical electrostatic quadrupole, which is installed in JM-400 pulse electrostatic accelerator, are described. This electrostatic quadrupole is not only used in neutron generator, but also suitable for ion injector as well as for low energy electron accelerator
Cylindrical Induction Melter Modicon Control System
International Nuclear Information System (INIS)
Weeks, G.E.
1998-04-01
In the last several years an extensive R ampersand D program has been underway to develop a vitrification system to stabilize Americium (Am) and Curium (Cm) inventories at SRS. This report documents the Modicon control system designed for the 3 inch Cylindrical Induction Melter (CIM)
A cylindrical furnace for absorption spectral studies
Indian Academy of Sciences (India)
A cylindrical furnace with three heating zones, capable of providing a temperature of 1100°C, has been fabricated to enable recording of absorption spectra of high temperature species. The temperature of the furnace can be controlled to ± 1°C of the set temperature. The salient feature of this furnace is that the material ...
Penetration of sub-micron aerosol droplets in composite cylindrical filtration elements
International Nuclear Information System (INIS)
Geurts, Bernard J.; Pratte, Pascal; Stolz, Steffen; Stabbert, Regina; Poux, Valerie; Nordlund, Markus; Winkelmann, Christoph
2011-01-01
Advection-diffusion transport of aerosol droplets in composite cylindrical filtration elements is analyzed and compared to experimental data. The penetration, characterizing the fraction of droplets that passes through the pores of a filtration element, is quantified for a range of flow rates. The advection-diffusion transport in a laminar Poiseuille flow is treated numerically for slender pores using a finite difference approach in cylindrical coordinates. The algebraic dependence of the penetration on the Peclet number as predicted theoretically, is confirmed by experimental findings at a variety of aspect ratios of the cylindrical pores. The effective penetration associated with a composite filtration element consisting of a set of parallel cylindrical pores is derived. The overall penetration of heterogeneous composite filtration elements shows an algebraic dependence to the fourth power on the radii of the individual pores that are contained. This gives rise to strong variations in the overall penetration in cases with uneven distributions of pore sizes, highly favoring filtration by the larger pores. The overall penetration is computed for a number of basic geometries, providing a point of reference for filtration design and experimental verification.
Experimental and theoretical studies of cylindrical Hall thrusters
International Nuclear Information System (INIS)
Smirnov, Artem; Raitses, Yegeny; Fisch, Nathaniel J.
2007-01-01
The Hall thruster is a mature electric propulsion device that holds considerable promise in terms of the propellant saving potential. The annular design of the conventional Hall thruster, however, does not naturally scale to low power. The efficiency tends to be lower and the lifetime issues are more aggravated. Cylindrical geometry Hall thrusters have lower surface-to-volume ratio than conventional thrusters and, thus, seem to be more promising for scaling down. The cylindrical Hall thruster (CHT) is fundamentally different from the conventional design in the way the electrons are confined and the ion space charge is neutralized. The performances of both the large (9-cm channel diameter, 600-1000 W) and miniaturized (2.6-cm channel diameter, 50-300 W) CHTs are comparable with those of the state-of-the-art conventional (annular) design Hall thrusters of similar sizes. A comprehensive experimental and theoretical study of the CHT physics has been conducted, addressing the questions of electron cross-field transport, propellant ionization, plasma-wall interaction, and formation of the electron distribution function. Probe measurements in the harsh plasma environment of the microthruster were performed. Several interesting effects, such as the unusually high ionization efficiency and enhanced electron transport, were observed. Kinetic simulations suggest the existence of the strong fluctuation-enhanced electron diffusion and predict the non-Maxwellian shape of the electron distribution function. Through the acquired understanding of the new physics, ways for further optimization of this means for low-power space propulsion are suggested. Substantial flexibility in the magnetic field configuration of the CHT is the key tool in achieving the high-efficiency operation
Nonlinear saturation of the slab ITG instability and zonal flow generation with fully kinetic ions
Miecnikowski, Matthew T.; Sturdevant, Benjamin J.; Chen, Yang; Parker, Scott E.
2018-05-01
Fully kinetic turbulence models are of interest for their potential to validate or replace gyrokinetic models in plasma regimes where the gyrokinetic expansion parameters are marginal. Here, we demonstrate fully kinetic ion capability by simulating the growth and nonlinear saturation of the ion-temperature-gradient instability in shearless slab geometry assuming adiabatic electrons and including zonal flow dynamics. The ion trajectories are integrated using the Lorentz force, and the cyclotron motion is fully resolved. Linear growth and nonlinear saturation characteristics show excellent agreement with analogous gyrokinetic simulations across a wide range of parameters. The fully kinetic simulation accurately reproduces the nonlinearly generated zonal flow. This work demonstrates nonlinear capability, resolution of weak gradient drive, and zonal flow physics, which are critical aspects of modeling plasma turbulence with full ion dynamics.
Automatic low-order aberration correction based on geometrical optics for slab lasers.
Yu, Xin; Dong, Lizhi; Lai, Boheng; Yang, Ping; Liu, Yong; Kong, Qingfeng; Yang, Kangjian; Tang, Guomao; Xu, Bing
2017-02-20
In this paper, we present a method based on geometry optics to simultaneously correct low-order aberrations and reshape the beams of slab lasers. A coaxial optical system with three lenses is adapted. The positions of the three lenses are directly calculated based on the beam parameters detected by wavefront sensors. The initial sizes of the input beams are 1.8 mm×11 mm, and peak-to-valley (PV) values of the wavefront range up to several tens of microns. After automatic correction, the dimensions may reach nearly 22 mm×22 mm as expected, and PV values of the wavefront are less than 2 μm. The effectiveness and precision of this method are verified with experiments.
Mixing and solid suspension of up-down agitators in a slab tank
International Nuclear Information System (INIS)
Ramsey, C.J.
1989-01-01
Seven different up-down agitators were studied for their ability to produce mixing and solid suspension in a slab tank. Mixing times were measured as the time needed to disperse injected dye. The solid suspension studies determined the minimum stroke frequency of the agitators needed for complete off-bottom suspension. The effects of stroke frequency, n; amplitude, a; blade width, w; blade clearance, c; and liquid depth, h, and weight percent solids, X, were studied. The most effective geometry, in terms of mixing, solid suspension and design simplicity, was a single flat blade with minimum off-bottom clearance and a blade width/tank thickness ratio, w/T, of 0.74 at the maximum stroke amplitude studied. 15 refs., 7 figs
Complex and symplectic geometry
Medori, Costantino; Tomassini, Adriano
2017-01-01
This book arises from the INdAM Meeting "Complex and Symplectic Geometry", which was held in Cortona in June 2016. Several leading specialists, including young researchers, in the field of complex and symplectic geometry, present the state of the art of their research on topics such as the cohomology of complex manifolds; analytic techniques in Kähler and non-Kähler geometry; almost-complex and symplectic structures; special structures on complex manifolds; and deformations of complex objects. The work is intended for researchers in these areas.
Kulczycki, Stefan
2008-01-01
This accessible approach features two varieties of proofs: stereometric and planimetric, as well as elementary proofs that employ only the simplest properties of the plane. A short history of geometry precedes a systematic exposition of the principles of non-Euclidean geometry.Starting with fundamental assumptions, the author examines the theorems of Hjelmslev, mapping a plane into a circle, the angle of parallelism and area of a polygon, regular polygons, straight lines and planes in space, and the horosphere. Further development of the theory covers hyperbolic functions, the geometry of suff
Effect of tool geometry on friction stir spot welding of polypropylene sheets
Directory of Open Access Journals (Sweden)
M. K. Bilici
2012-10-01
Full Text Available The effects of tool geometry and properties on friction stir spot welding properties of polypropylene sheets were studied. Four different tool pin geometries, with varying pin angles, pin lengths, shoulder diameters and shoulder angles were used for friction stir spot welding. All the welding operations were done at the room temperature. Lap-shear tensile tests were carried out to find the weld static strength. Weld cross section appearance observations were also done. From the experiments the effect of tool geometry on friction stir spot weld formation and weld strength were determined. The optimum tool geometry for 4 mm thick polypropylene sheets were determined. The tapered cylindrical pin gave the biggest and the straight cylindrical pin gave the lowest lap-shear fracture load.
The large Bonin deep Event of 30 May 2015: Seismogenesis in a Detached and Fragmented Slab
Okal, Emile; Kirby, Stephen H.
2016-04-01
The earthquake of 30 May 2015 in the Bonin Island was exceptional in many respects: it was the fifth largest deep earthquake ever recorded (7.8 E27 dyn*cm; Mw = 7.9); at h = 680 km, it was 100 km deeper than any known event in that subduction zone and 150 km distant from its nearest neighbor (including relocated historical events dating back to the 1920s); it was displaced as much as 150 km East of the prolongation of the mapped Wadati-Benioff Zone; and finally its focal mechanism was close to the opposite of the down-dip compression prevailing for the deepest known earthquakes. Other cases of "detached" deep earthquakes occurring in highwavespeed, high-Q slab material, have been described in front of subduction zones, notably by Fukao et al. [19092], Van der Hilst et al. [1993] aand Okal [2001]. The geometry of the 2015 Bonin event is reminiscent of that of the cluster of (much smaller) seismic events beneath the North Fiji Basin, which appear be unrelated to presently active W-B systems, but rather express seismogenesis in detached or fragmented slab material that has foundered to the bottom of the transition zone [Kirby et al., 1996; Okal and Kirby, 1998], where stresses may be generated by heterogeneous volume changes associated with the metastable olivine-spinel metamorphic reaction. How and why slab fragments become detached has been suggested to possibly involve collisions of oceanic plateaux or island arcs with oceanic forearcs, leading to arc reversal and/or fragmentation of normal oceanic and plateau lithosphere. In this context, the Igasawara Plateau is currently colliding with the Bonin forearc just to the South of the 2015 deep event. The Bonin Ridge to the North may represent a section of thick remnant crust that otherwise detached from its slab and later foundered in the mantle all the way to the bottom of the transition zone, stagnating to this day in the source region of the 2015 shock.
Pacific plate slab pull and intraplate deformation in the early Cenozoic
Directory of Open Access Journals (Sweden)
N. P. Butterworth
2014-08-01
Full Text Available Large tectonic plates are known to be susceptible to internal deformation, leading to a~range of phenomena including intraplate volcanism. However, the space and time dependence of intraplate deformation and its relationship with changing plate boundary configurations, subducting slab geometries, and absolute plate motion is poorly understood. We utilise a buoyancy-driven Stokes flow solver, BEM-Earth, to investigate the contribution of subducting slabs through time on Pacific plate motion and plate-scale deformation, and how this is linked to intraplate volcanism. We produce a series of geodynamic models from 62 to 42 Ma in which the plates are driven by the attached subducting slabs and mantle drag/suction forces. We compare our modelled intraplate deformation history with those types of intraplate volcanism that lack a clear age progression. Our models suggest that changes in Cenozoic subduction zone topology caused intraplate deformation to trigger volcanism along several linear seafloor structures, mostly by reactivation of existing seamount chains, but occasionally creating new volcanic chains on crust weakened by fracture zones and extinct ridges. Around 55 Ma, subduction of the Pacific-Izanagi ridge reconfigured the major tectonic forces acting on the plate by replacing ridge push with slab pull along its northwestern perimeter, causing lithospheric extension along pre-existing weaknesses. Large-scale deformation observed in the models coincides with the seamount chains of Hawaii, Louisville, Tokelau and Gilbert during our modelled time period of 62 to 42 Ma. We suggest that extensional stresses between 72 and 52 Ma are the likely cause of large parts of the formation of the Gilbert chain and that localised extension between 62 and 42 Ma could cause late-stage volcanism along the Musicians volcanic ridges. Our models demonstrate that early Cenozoic changes in Pacific plate driving forces only cause relatively minor changes in Pacific
Roe, John
2003-01-01
Coarse geometry is the study of spaces (particularly metric spaces) from a 'large scale' point of view, so that two spaces that look the same from a great distance are actually equivalent. This point of view is effective because it is often true that the relevant geometric properties of metric spaces are determined by their coarse geometry. Two examples of important uses of coarse geometry are Gromov's beautiful notion of a hyperbolic group and Mostow's proof of his famous rigidity theorem. The first few chapters of the book provide a general perspective on coarse structures. Even when only metric coarse structures are in view, the abstract framework brings the same simplification as does the passage from epsilons and deltas to open sets when speaking of continuity. The middle section reviews notions of negative curvature and rigidity. Modern interest in large scale geometry derives in large part from Mostow's rigidity theorem and from Gromov's subsequent 'large scale' rendition of the crucial properties of n...