Converting point-wise nuclear cross sections to pole representation using regularized vector fitting

Science.gov (United States)

Peng, Xingjie; Ducru, Pablo; Liu, Shichang; Forget, Benoit; Liang, Jingang; Smith, Kord

2018-03-01

Direct Doppler broadening of nuclear cross sections in Monte Carlo codes has been widely sought for coupled reactor simulations. One recent approach proposed analytical broadening using a pole representation of the commonly used resonance models and the introduction of a local windowing scheme to improve performance (Hwang, 1987; Forget et al., 2014; Josey et al., 2015, 2016). This pole representation has been achieved in the past by converting resonance parameters in the evaluation nuclear data library into poles and residues. However, cross sections of some isotopes are only provided as point-wise data in ENDF/B-VII.1 library. To convert these isotopes to pole representation, a recent approach has been proposed using the relaxed vector fitting (RVF) algorithm (Gustavsen and Semlyen, 1999; Gustavsen, 2006; Liu et al., 2018). This approach however needs to specify ahead of time the number of poles. This article addresses this issue by adding a poles and residues filtering step to the RVF procedure. This regularized VF (ReV-Fit) algorithm is shown to efficiently converge the poles close to the physical ones, eliminating most of the superfluous poles, and thus enabling the conversion of point-wise nuclear cross sections.

The average crossing number of equilateral random polygons

International Nuclear Information System (INIS)

Diao, Y; Dobay, A; Kusner, R B; Millett, K; Stasiak, A

2003-01-01

In this paper, we study the average crossing number of equilateral random walks and polygons. We show that the mean average crossing number ACN of all equilateral random walks of length n is of the form (3/16)n ln n + O(n). A similar result holds for equilateral random polygons. These results are confirmed by our numerical studies. Furthermore, our numerical studies indicate that when random polygons of length n are divided into individual knot types, the for each knot type K can be described by a function of the form = a(n-n 0 )ln(n-n 0 ) + b(n-n 0 ) + c where a, b and c are constants depending on K and n 0 is the minimal number of segments required to form K. The profiles diverge from each other, with more complex knots showing higher than less complex knots. Moreover, the profiles intersect with the profile of all closed walks. These points of intersection define the equilibrium length of K, i.e., the chain length n e (K) at which a statistical ensemble of configurations with given knot type K-upon cutting, equilibration and reclosure to a new knot type K'-does not show a tendency to increase or decrease . This concept of equilibrium length seems to be universal, and applies also to other length-dependent observables for random knots, such as the mean radius of gyration g >

A subtraction scheme for computing QCD jet cross sections at NNLO: regularization of doubly-real emissions

International Nuclear Information System (INIS)

Somogyi, Gabor; Trocsanyi, Zoltan; Del Duca, Vittorio

2007-01-01

We present a generalization of the dipole subtraction scheme for computing jet cross sections in electron-positron annihilation at next-to-next-to-leading order accuracy in perturbative QCD. In this first part we deal with the regularization of the doubly-real contribution to the NNLO correction

A subtraction scheme for computing QCD jet cross sections at NNLO: regularization of doubly-real emissions

Energy Technology Data Exchange (ETDEWEB)

Somogyi, Gabor [University of Debrecen and Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, PO Box 51 (Hungary); Trocsanyi, Zoltan [University of Debrecen and Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, PO Box 51 (Hungary); Del Duca, Vittorio [Istituto Nazionale di Fisica Nucleare, Sez. di Torino, via P. Giuria, 1 - 10125 Turin (Italy)

2007-01-15

We present a generalization of the dipole subtraction scheme for computing jet cross sections in electron-positron annihilation at next-to-next-to-leading order accuracy in perturbative QCD. In this first part we deal with the regularization of the doubly-real contribution to the NNLO correction.

A subtraction scheme for computing QCD jet cross sections at NNLO: regularization of real-virtual emission

Energy Technology Data Exchange (ETDEWEB)

Somogyi, Gabor; Trocsanyi, Zoltan [University of Debrecen and Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, PO Box 51 (Hungary)

2007-01-15

We present a generalization of the dipole subtraction scheme for computing jet cross sections in electron-positron annihilation at next-to-next-to-leading order accuracy in perturbative QCD. In this second part we deal with the regularization of the real-virtual contribution to the NNLO correction.

Development of a cross-section based stream package for MODFLOW

Science.gov (United States)

Ou, G.; Chen, X.; Irmak, A.

2012-12-01

Accurate simulation of stream-aquifer interactions for wide rivers using the streamflow routing package in MODFLOW is very challenging. To better represent a wide river spanning over multiple model grid cells, a Cross-Section based streamflow Routing (CSR) package is developed and incorporated into MODFLOW to simulate the interaction between streams and aquifers. In the CSR package, a stream segment is represented as a four-point polygon instead of a polyline which is traditionally used in streamflow routing simulation. Each stream segment is composed of upstream and downstream cross-sections. A cross-section consists of a number of streambed points possessing coordinates, streambed thicknesses and streambed hydraulic conductivities to describe the streambed geometry and hydraulic properties. The left and right end points are used to determine the locations of the stream segments. According to the cross-section geometry and hydraulic properties, CSR calculates the new stream stage at the cross-section using the Brent's method to solve the Manning's Equation. A module is developed to automatically compute the area of the stream segment polygon on each intersected MODFLOW grid cell as the upstream and downstream stages change. The stream stage and streambed hydraulic properties of model grids are interpolated based on the streambed points. Streambed leakage is computed as a function of streambed conductance and difference between the groundwater level and stream stage. The Muskingum-Cunge flow routing scheme with variable parameters is used to simulate the streamflow as the groundwater (discharge or recharge) contributes as lateral flows. An example is used to illustrate the capabilities of the CSR package. The result shows that the CSR is applicable to describing the spatial and temporal variation in the interaction between streams and aquifers. The input data become simple due to that the internal program automatically interpolates the cross-section data to each

Casimir effect in hyperbolic polygons

International Nuclear Information System (INIS)

Ahmedov, H

2007-01-01

Using the point splitting regularization method and the trace formula for the spectra of quantum-mechanical systems in hyperbolic polygons which are the fundamental domains of discrete isometry groups acting in the two-dimensional hyperboloid we calculate the Casimir energy for massless scalar fields in hyperbolic polygons. The dependence of the vacuum energy on the number of vertices is established

Perceptually stable regions for arbitrary polygons.

Science.gov (United States)

Rocha, J

2003-01-01

Zou and Yan have recently developed a skeletonization algorithm of digital shapes based on a regularity/singularity analysis; they use the polygon whose vertices are the boundary pixels of the image to compute a constrained Delaunay triangulation (CDT) in order to find local symmetries and stable regions. Their method has produced good results but it is slow since its complexity depends on the number of contour pixels. This paper presents an extension of their technique to handle arbitrary polygons, not only polygons of short edges. Consequently, not only can we achieve results as good as theirs for digital images, but we can also compute skeletons of polygons of any number of edges. Since we can handle polygonal approximations of figures, the skeletons are more resilient to noise and faster to process.

Fast incorporation of optical flow into active polygons.

Science.gov (United States)

Unal, Gozde; Krim, Hamid; Yezzi, Anthony

2005-06-01

In this paper, we first reconsider, in a different light, the addition of a prediction step to active contour-based visual tracking using an optical flow and clarify the local computation of the latter along the boundaries of continuous active contours with appropriate regularizers. We subsequently detail our contribution of computing an optical flow-based prediction step directly from the parameters of an active polygon, and of exploiting it in object tracking. This is in contrast to an explicitly separate computation of the optical flow and its ad hoc application. It also provides an inherent regularization effect resulting from integrating measurements along polygon edges. As a result, we completely avoid the need of adding ad hoc regularizing terms to the optical flow computations, and the inevitably arbitrary associated weighting parameters. This direct integration of optical flow into the active polygon framework distinguishes this technique from most previous contour-based approaches, where regularization terms are theoretically, as well as practically, essential. The greater robustness and speed due to a reduced number of parameters of this technique are additional and appealing features.

Shape and Symmetry Determine Two-Dimensional Melting Transitions of Hard Regular Polygons

Directory of Open Access Journals (Sweden)

Joshua A. Anderson

2017-04-01

Full Text Available The melting transition of two-dimensional systems is a fundamental problem in condensed matter and statistical physics that has advanced significantly through the application of computational resources and algorithms. Two-dimensional systems present the opportunity for novel phases and phase transition scenarios not observed in 3D systems, but these phases depend sensitively on the system and, thus, predicting how any given 2D system will behave remains a challenge. Here, we report a comprehensive simulation study of the phase behavior near the melting transition of all hard regular polygons with 3≤n≤14 vertices using massively parallel Monte Carlo simulations of up to 1×10^{6} particles. By investigating this family of shapes, we show that the melting transition depends upon both particle shape and symmetry considerations, which together can predict which of three different melting scenarios will occur for a given n. We show that systems of polygons with as few as seven edges behave like hard disks; they melt continuously from a solid to a hexatic fluid and then undergo a first-order transition from the hexatic phase to the isotropic fluid phase. We show that this behavior, which holds for all 7≤n≤14, arises from weak entropic forces among the particles. Strong directional entropic forces align polygons with fewer than seven edges and impose local order in the fluid. These forces can enhance or suppress the discontinuous character of the transition depending on whether the local order in the fluid is compatible with the local order in the solid. As a result, systems of triangles, squares, and hexagons exhibit a Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY predicted continuous transition between isotropic fluid and triatic, tetratic, and hexatic phases, respectively, and a continuous transition from the appropriate x-atic to the solid. In particular, we find that systems of hexagons display continuous two-step KTHNY melting. In

Slow relaxation in weakly open rational polygons.

Science.gov (United States)

Kokshenev, Valery B; Vicentini, Eduardo

2003-07-01

The interplay between the regular (piecewise-linear) and irregular (vertex-angle) boundary effects in nonintegrable rational polygonal billiards (of m equal sides) is discussed. Decay dynamics in polygons (of perimeter P(m) and small opening Delta) is analyzed through the late-time survival probability S(m) approximately equal t(-delta). Two distinct slow relaxation channels are established. The primary universal channel exhibits relaxation of regular sliding orbits, with delta=1. The secondary channel is given by delta>1 and becomes open when m>P(m)/Delta. It originates from vertex order-disorder dual effects and is due to relaxation of chaoticlike excitations.

The magnetic field generated by a rotating charged polygon

International Nuclear Information System (INIS)

Wan, Songlin; Chen, Xiangyu; Teng, Baohua; Fu, Hao; Li, Yefeng; Wu, Minghe; Wu, Shaoyi; Balfour, E A

2014-01-01

The magnetic field along the symmetry axis of a regular polygon carrying a uniform electric charge on its edges is calculated systematically when the polygon is rotated about this axis of symmetry. A group of circular current-carrying coils arranged concentrically about the axis of the polygon has been designed to simulate the magnetic field characteristics of the rotating charged polygon. The magnetic field of the simulated coils is measured using the PASCO magnetic field sensor. The results show that the theoretical calculation agrees well with the experimental results. (paper)

Investigating the structure of a vortex flow in the closed polygonal containers

Science.gov (United States)

Podolskaya, I. Yu; Bakakin, G. V.; Naumov, I. V.

2018-03-01

The structure of confined vortex flow generated by a rotating lid in a closed container with polygonal cross-section geometry (eight, six and five angles) has been investigated numerically for different height/radius aspect ratios h from 3.0 to 4.5 and for Reynold numbers ranging from 1500 to 3000. The critical Reynolds numbers at which the flow becomes unsteady were determined numerically by STAR-CCM+ computational fluid dynamics software for pentagonal and hexagonal cross-section configurations. The obtained results were compared with the flow structure in the closed cylindrical container. The boundary of a nonstationarity in polygonal containers is found to shift to the region of smaller aspect ratio and smaller Reynolds numbers with a decrease in the number of angles in the cross-section of the container relative to the boundary in a cylindrical container. It is additionally established that the structure of the flow in the near-axis region remains similar to the vortex structure in the cylinder, therefore the shape of the container does not influence the near-axis region.

The growth of the mean average crossing number of equilateral polygons in confinement

International Nuclear Information System (INIS)

Arsuaga, J; Borgo, B; Scharein, R; Diao, Y

2009-01-01

The physical and biological properties of collapsed long polymer chains as well as of highly condensed biopolymers (such as DNA in all organisms) are known to be determined, at least in part, by their topological and geometrical properties. With this purpose of characterizing the topological properties of such condensed systems equilateral random polygons restricted to confined volumes are often used. However, very few analytical results are known. In this paper, we investigate the effect of volume confinement on the mean average crossing number (ACN) of equilateral random polygons. The mean ACN of knots and links under confinement provides a simple alternative measurement for the topological complexity of knots and links in the statistical sense. For an equilateral random polygon of n segments without any volume confinement constrain, it is known that its mean ACN (ACN) is of the order 3/16 n log n + O(n). Here we model the confining volume as a simple sphere of radius R. We provide an analytical argument which shows that (ACN) of an equilateral random polygon of n segments under extreme confinement (meaning R 2 ). We propose to model the growth of (ACN) as a(R)n 2 + b(R)nln(n) under a less-extreme confinement condition, where a(R) and b(R) are functions of R with R being the radius of the confining sphere. Computer simulations performed show a fairly good fit using this model.

Cultural and Mathematical Meanings of Regular Octagons in Mesopotamia: Examining Islamic Art Designs

Directory of Open Access Journals (Sweden)

Jeanam Park

2018-03-01

Full Text Available The most common regular polygon in Islamic art design is the octagon. Historical evidence of the use of an 8-star polygon and an 8-fold rosette dates back to Jemdet Nasr (3100-2900 B.C. in Mesopotamia. Additionally, in ancient Egypt, octagons can be found in mathematical problem (Ahmose papyrus, Problem number 48, household goods (papyrus storage, architecture (granite columns and decorations (palace decorations. The regular octagon which is a fundamentally important element of Islamic art design, is widely used as arithmetic objects in metric algebra along with other regular polygons in Mesopotamia. The 8-point star polygon has long been a symbol of the ancient Sumerian goddess Inanna and her East Semitic counterpart Ishtar. During the Neo-Assyrian period, the 8-fold rosette occasionally replaced the star as the symbol of Ishtar. In this paper, we discuss how octagonal design prevailed in the Islamic region since the late ninth century, and has existed in Mesopotamia from Jemdet Nasr to the end of third century B.C. We describe reasons why the geometric pattern of regular polygons, including regular octagons, developed in the Islamic world. Furthermore, we also discuss mathematical meanings of regular polygons.

Steady state of tapped granular polygons

International Nuclear Information System (INIS)

Carlevaro, Carlos M; Pugnaloni, Luis A

2011-01-01

The steady state packing fraction of a tapped granular bed is studied for different grain shapes via a discrete element method. Grains are monosized regular polygons, from triangles to icosagons. Comparisons with disc packings show that the steady state packing fraction as a function of the tapping intensity presents the same general trends in polygon packings. However, better packing fractions are obtained, as expected, for shapes that can tessellate the plane (triangles, squares and hexagons). In addition, we find a sharp transition for packings of polygons with more than 13 vertices signaled by a discontinuity in the packing fraction at a particular tapping intensity. Density fluctuations for most shapes are consistent with recent experimental findings in disc packing; however, a peculiar behavior is found for triangles and squares

Random walks and polygons in tight confinement

International Nuclear Information System (INIS)

Diao, Y; Ernst, C; Ziegler, U

2014-01-01

We discuss the effect of confinement on the topology and geometry of tightly confined random walks and polygons. Here the walks and polygons are confined in a sphere of radius R ≥ 1/2 and the polygons are equilateral with n edges of unit length. We illustrate numerically that for a fixed length of random polygons the knotting probability increases to one as the radius decreases to 1/2. We also demonstrate that for random polygons (walks) the curvature increases to πn (π(n – 1)) as the radius approaches 1/2 and that the torsion decreases to ≈ πn/3 (≈ π(n – 1)/3). In addition we show the effect of length and confinement on the average crossing number of a random polygon

Excitons in Core-Shell Nanowires with Polygonal Cross Sections.

Science.gov (United States)

Sitek, Anna; Urbaneja Torres, Miguel; Torfason, Kristinn; Gudmundsson, Vidar; Bertoni, Andrea; Manolescu, Andrei

2018-04-11

The distinctive prismatic geometry of semiconductor core-shell nanowires leads to complex localization patterns of carriers. Here, we describe the formation of optically active in-gap excitonic states induced by the interplay between localization of carriers in the corners and their mutual Coulomb interaction. To compute the energy spectra and configurations of excitons created in the conductive shell, we use a multielectron numerical approach based on the exact solution of the multiparticle Hamiltonian for electrons in the valence and conduction bands, which includes the Coulomb interaction in a nonperturbative manner. We expose the formation of well-separated quasidegenerate levels, and focus on the implications of the electron localization in the corners or on the sides of triangular, square, and hexagonal cross sections. We obtain excitonic in-gap states associated with symmetrically distributed electrons in the spin singlet configuration. They acquire large contributions due to Coulomb interaction, and thus are shifted to much higher energies than other states corresponding to the conduction electron and the vacancy localized in the same corner. We compare the results of the multielectron method with those of an electron-hole model, and we show that the latter does not reproduce the singlet excitonic states. We also obtain the exciton lifetime and explain selection rules which govern the recombination process.

Regularized unfolding of jet cross sections in deep-inelastic ep scattering at HERA and determination of the strong coupling constant

Energy Technology Data Exchange (ETDEWEB)

Britzger, Daniel Andreas

2013-10-15

In this thesis double-differential cross sections for jet production in neutral current deep-inelastic e{sup {+-}}p scattering (DIS) are presented at the center-of-mass energy of {radical}(s)=319 GeV, and in the kinematic range of the squared four-momentum transfer 150< Q{sup 2}<15 000 GeV{sup 2} and the inelasticity 0.2regularized unfolding procedure which features a correct propagation of the statistical uncertainty. The matrix based unfolding corrects the neutral current DIS, the inclusive jet, the dijet and the trijet measurements simultaneously, and it considers migrations in up to eight variables. The simultaneous unfolding enables to constrain contributions from jet multiplicities differing between detector and hadron level using the neutral current DIS kinematics of such events. Furthermore, jet cross sections normalized to the inclusive neutral current DIS cross section and ratios of jet cross sections are obtained, since the statistical correlations between these observables are known. The jet cross sections are used to determine the strong coupling constant {alpha}{sub s}(M{sub Z}) at the scale of the mass of the Z{sup 0} boson in the framework of perturbative quantum chromodynamics in next-to-leading order. Values are derived separately for the absolute

Fabrication and in situ compression testing of Mg micropillars with a nontrivial cross section: Influence of micropillar geometry on mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Bočan, Jiří [Laboratory of Nanostructures and Nanomaterials, Institute of Physics, Czech Academy of Sciences, Na Slovance 1999/2, CZ-12821 Praha 8 (Czech Republic); Tsurekawa, Sadahiro [Division of Materials Science, Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Jäger, Aleš, E-mail: aljag@seznam.cz [Laboratory of Nanostructures and Nanomaterials, Institute of Physics, Czech Academy of Sciences, Na Slovance 1999/2, CZ-12821 Praha 8 (Czech Republic)

2017-02-27

Micropillars with a nontrivial cross-sectional shape but constant cross-sectional area were fabricated from a pure magnesium single crystal with (0001) orientation by a focused gallium ion beam using a modified annular milling method. The basic mechanical properties (compressive modulus, strength at different plastic strain levels and hardening exponent) of those structures were determined under compression by means of in situ nanoindentation in scanning electron microscope and correlated by the micropillar cross-sectional circumference. It was observed that the modulus and strength increased with increasing circumference. The values of the modulus for the complex cross sectional shapes are on average higher by 5%, and the yield strength, ranging between 274 MPa and 342 MPa, is on average higher by 20% relative to micropillars with a simple circular or polygonal cross section. Surprisingly, the hardening exponent remains nearly constant regardless of the micropillar cross section.

The structure of near polygons with quads

NARCIS (Netherlands)

Brouwer, A.E.; Wilbrink, H.A.

1983-01-01

We develop a structure theory for near polygons with quads. Main results are the existence of sub 2j-gons for 2jd and the nonexistence of regular sporadic 2d-gons for d4 with s>1 and t 2>1 and t 3t 2(t 2+1).

Ares Vallis Polygons

Science.gov (United States)

2002-01-01

[figure removed for brevity, see original site] This jumble of eroded ridges and mesas occurs within Ares Vallis, one of the largest catastrophic outflow channels on the planet. Floods raged through this channel, portions of which are up to 25 km wide, pouring out into the Chryse Basin to the north. Close inspection of the THEMIS image reveals polygonal shapes on the floor of the channel system. Polygonal terrain on Mars is fairly common although the variety of forms and scales of the polygons suggests multiple modes of origin. Those in Ares Vallis resemble giant desiccation polygons that form in soils on Earth when a moist layer at depth drys out. While polygons can form in icy soils (permafrost) and even lava flows, their presence in a channel thought to have been carved by flowing water is at least consistent with a mode of origin that involved liquid water.Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Justification of the Shape of a Non-Circular Cross-Section for Drilling With a Roller Cutter

Science.gov (United States)

Buyalich, Gennady; Husnutdinov, Mikhail

2017-11-01

The parameters of the shape of non-circular cross-section affect not only the process of blasting, but also the design of the tool and the process of drilling as well. In the conditions of open-pit mining, it is reasonable to use a roller cutter to produce a non-circular cross-section of blasting holes. With regard to the roller cutter, the impact of the cross-section shape on the oscillations of the axial force arising upon its rotation is determined. It is determined that a polygonal shape with rounded comers of the borehole walls connections and their convex shape, which ensures a smaller range of the total axial force and the torque deflecting the bit from the axis of its rotation is the rational form of the non-circular cross-section of the borehole in terms of bit design. It has been shown that the ratio of the number of cutters to the number of borehole corners must be taken into account when justifying the shape of the cross-section, both from the point of view of the effectiveness of the explosion action and from the point of view of the rational design of the bit.

Atmospheres of polygons and knotted polygons

International Nuclear Information System (INIS)

Janse Rensburg, E J Janse; Rechnitzer, A

2008-01-01

In this paper we define two statistics a + (ω) and a - (ω), the positive and negative atmospheres of a lattice polygon ω of fixed length n. These statistics have the property that (a + (ω))/(a - (ω)) = p n+2 /p n , where p n is the number of polygons of length n, counted modulo translations. We use the pivot algorithm to sample polygons and to compute the corresponding average atmospheres. Using these data, we directly estimate the growth constants of polygons in two and three dimensions. We find that μ=2.63805±0.00012 in two dimensions and μ=4.683980±0.000042±0.000067 in three dimensions, where the error bars are 67% confidence intervals, and the second error bar in the three-dimensional estimate of μ is an estimated systematic error. We also compute atmospheres of polygons of fixed knot type K sampled by the BFACF algorithm. We discuss the implications of our results and show that different knot types have atmospheres which behave dramatically differently at small values of n

Aberdeen polygons: computer displays of physiological profiles for intensive care.

Science.gov (United States)

Green, C A; Logie, R H; Gilhooly, K J; Ross, D G; Ronald, A

1996-03-01

The clinician in an intensive therapy unit is presented regularly with a range of information about the current physiological state of the patients under care. This information typically comes from a variety of sources and in a variety of formats. A more integrated form of display incorporating several physiological parameters may be helpful therefore. Three experiments are reported that explored the potential use of analogue, polygon diagrams to display physiological data from patients undergoing intensive therapy. Experiment 1 demonstrated that information can be extracted readily from such diagrams comprising 8- or 10-sided polygons, but with an advantage for simpler polygons and for information displayed at the top of the diagram. Experiment 2 showed that colour coding removed these biases for simpler polygons and the top of the diagram, together with speeding the processing time. Experiment 3 used polygons displaying patterns of physiological data that were consistent with typical conditions observed in the intensive care unit. It was found that physicians can readily learn to recognize these patterns and to diagnose both the nature and severity of the patient's physiological state. These polygon diagrams appear to have some considerable potential for use in providing on-line summary information of a patient's physiological state.

Multifrequency Piezoelectric Energy Harvester Based on Polygon-Shaped Cantilever Array

Directory of Open Access Journals (Sweden)

Dalius Mažeika

2018-01-01

Full Text Available This paper focuses on numerical and experimental investigations of a novel design piezoelectric energy harvester. Investigated harvester is based on polygon-shaped cantilever array and employs multifrequency operating principle. It consists of eight cantilevers with irregular design of cross-sectional area. Cantilevers are connected to each other by specific angle to form polygon-shaped structure. Moreover, seven seismic masses with additional lever arms are added in order to create additional rotation moment. Numerical investigation showed that piezoelectric polygon-shaped energy harvester has five natural frequencies in the frequency range from 10 Hz to 240 Hz, where the first and the second bending modes of the cantilevers are dominating. Maximum output voltage density and energy density equal to 50.03 mV/mm3 and 604 μJ/mm3, respectively, were obtained during numerical simulation. Prototype of piezoelectric harvester was made and experimental investigation was performed. Experimental measurements of the electrical characteristics showed that maximum output voltage density, energy density, and output power are 37.5 mV/mm3, 815.16 μJ/mm3, and 65.24 μW, respectively.

Complete heat transfer solutions of an insulated regular polygonal pipe by using a PWTR model

International Nuclear Information System (INIS)

Wong, K.-L.; Chou, H.-M.; Li, Y.-H.

2004-01-01

The heat transfer characteristics for insulated long regular polygonal (including circular) pipes are analyzed by using the same PWRT model in the present study as that used by Chou and Wong previously [Energy Convers. Manage. 44 (4) (2003) 629]. The thermal resistance of the inner convection term and the pipe conduction term in the heat transfer rate are not neglected in the present study. Thus, the complete heat transfer solution will be obtained. The present results can be applied more extensively to practical situations, such as heat exchangers. The results of the critical thickness t cr and the neutral thickness t e are independent of the values of J (generated by the combined effect of the inner convection term and the pipe conduction term). However, the heat transfer rates are dependent on the values of J. The present study shows that the thermal resistance of the inner convection term and the pipe conduction term cannot be neglected in the heat transfer equation in situations of low to medium inner convection coefficients h i and/or low to medium pipe conductivities K, especially in situations with large pipe sizes or/and great outer convection coefficients h 0

Fully double-logarithm-resummed cross sections

International Nuclear Information System (INIS)

Albino, S.; Bolzoni, P.; Kniehl, B.A.; Kotikov, A.

2011-01-01

We calculate the complete double logarithmic contribution to cross sections for semi-inclusive hadron production in the modified minimal-subtraction (MS-bar) scheme by applying dimensional regularization to the double logarithm approximation. The full double logarithmic contribution to the coefficient functions for inclusive hadron production in e + e - annihilation is obtained in this scheme for the first time. Our result agrees with all fixed order results in the literature, which extend to next-to-next-to-leading order.

Convex Lattice Polygons

Science.gov (United States)

Scott, Paul

2006-01-01

A "convex" polygon is one with no re-entrant angles. Alternatively one can use the standard convexity definition, asserting that for any two points of the convex polygon, the line segment joining them is contained completely within the polygon. In this article, the author provides a solution to a problem involving convex lattice polygons.

Control Point Generated PLS - polygons

Data.gov (United States)

Minnesota Department of Natural Resources — The Control Point Generated PLS layer contains line and polygon features to the 1/4 of 1/4 PLS section (approximately 40 acres) and government lot level. The layer...

Spectral analysis of point-vortex dynamics: first application to vortex polygons in a circular domain

International Nuclear Information System (INIS)

Speetjens, M F M; Meleshko, V V; Van Heijst, G J F

2014-01-01

The present study addresses the classical problem of the dynamics and stability of a cluster of N-point vortices of equal strength arranged in a polygonal configuration (‘N-vortex polygons’). In unbounded domains, such N-vortex polygons are unconditionally stable for N⩽7. Confinement in a circular domain tightens the stability conditions to N⩽6 and a maximum polygon size relative to the domain radius. This work expands on existing studies on stability and integrability by a first giving an exploratory spectral analysis of the dynamics of N vortex polygons in circular domains. Key to this is that the spectral signature of the time evolution of vortex positions reflects their qualitative behaviour. Expressing vortex motion by a generic evolution operator (the so-called Koopman operator) provides a rigorous framework for such spectral analyses. This paves the way to further differentiation and classification of point-vortex behaviour beyond stability and integrability. The concept of Koopman-based spectral analysis is demonstrated for N-vortex polygons. This reveals that conditional stability can be seen as a local form of integrability and confirms an important generic link between spectrum and dynamics: discrete spectra imply regular (quasi-periodic) motion; continuous (sub-)spectra imply chaotic motion. Moreover, this exposes rich nonlinear dynamics as intermittency between regular and chaotic motion and quasi-coherent structures formed by chaotic vortices. (ss 1)

Image segmentation by hierarchial agglomeration of polygons using ecological statistics

Science.gov (United States)

Prasad, Lakshman; Swaminarayan, Sriram

2013-04-23

A method for rapid hierarchical image segmentation based on perceptually driven contour completion and scene statistics is disclosed. The method begins with an initial fine-scale segmentation of an image, such as obtained by perceptual completion of partial contours into polygonal regions using region-contour correspondences established by Delaunay triangulation of edge pixels as implemented in VISTA. The resulting polygons are analyzed with respect to their size and color/intensity distributions and the structural properties of their boundaries. Statistical estimates of granularity of size, similarity of color, texture, and saliency of intervening boundaries are computed and formulated into logical (Boolean) predicates. The combined satisfiability of these Boolean predicates by a pair of adjacent polygons at a given segmentation level qualifies them for merging into a larger polygon representing a coarser, larger-scale feature of the pixel image and collectively obtains the next level of polygonal segments in a hierarchy of fine-to-coarse segmentations. The iterative application of this process precipitates textured regions as polygons with highly convolved boundaries and helps distinguish them from objects which typically have more regular boundaries. The method yields a multiscale decomposition of an image into constituent features that enjoy a hierarchical relationship with features at finer and coarser scales. This provides a traversable graph structure from which feature content and context in terms of other features can be derived, aiding in automated image understanding tasks. The method disclosed is highly efficient and can be used to decompose and analyze large images.

QUADRATIC SERENDIPITY FINITE ELEMENTS ON POLYGONS USING GENERALIZED BARYCENTRIC COORDINATES.

Science.gov (United States)

Rand, Alexander; Gillette, Andrew; Bajaj, Chandrajit

2014-01-01

We introduce a finite element construction for use on the class of convex, planar polygons and show it obtains a quadratic error convergence estimate. On a convex n -gon, our construction produces 2 n basis functions, associated in a Lagrange-like fashion to each vertex and each edge midpoint, by transforming and combining a set of n ( n + 1)/2 basis functions known to obtain quadratic convergence. The technique broadens the scope of the so-called 'serendipity' elements, previously studied only for quadrilateral and regular hexahedral meshes, by employing the theory of generalized barycentric coordinates. Uniform a priori error estimates are established over the class of convex quadrilaterals with bounded aspect ratio as well as over the class of convex planar polygons satisfying additional shape regularity conditions to exclude large interior angles and short edges. Numerical evidence is provided on a trapezoidal quadrilateral mesh, previously not amenable to serendipity constructions, and applications to adaptive meshing are discussed.

Floating polygon soup

OpenAIRE

Colleu , Thomas; Morin , Luce; Pateux , Stéphane; Labit , Claude

2011-01-01

International audience; This paper presents a new representation called floating polygon soup for applications like 3DTV and FTV (Free Viewpoint Television). This representation is based on 3D polygons and takes as input MVD data. It extends the previously proposed polygon soup representation which is appropriate for both compression, transmission and rendering stages. The floating polygon soup conserves these advantages while also taking into account misalignments at the view synthesis stage...

Two-convex polygons

OpenAIRE

Aichholzer, Oswin; Aurenhammer, Franz; Hurtado Díaz, Fernando Alfredo; Ramos, Pedro A.; Urrutia, J.

2009-01-01

We introduce a notion of k-convexity and explore some properties of polygons that have this property. In particular, 2-convex polygons can be recognized in O(n log n) time, and k-convex polygons can be triangulated in O(kn) time.

Exact moduli space metrics for hyperbolic vortex polygons

International Nuclear Information System (INIS)

Krusch, S.; Speight, J. M.

2010-01-01

Exact metrics on some totally geodesic submanifolds of the moduli space of static hyperbolic N-vortices are derived. These submanifolds, denoted as Σ n,m , are spaces of C n -invariant vortex configurations with n single vortices at the vertices of a regular polygon and m=N-n coincident vortices at the polygon's center. The geometric properties of Σ n,m are investigated, and it is found that Σ n,n-1 is isometric to the hyperbolic plane of curvature -(3πn) -1 . The geodesic flow on Σ n,m and a geometrically natural variant of geodesic flow recently proposed by Collie and Tong ['The dynamics of Chern-Simons vortices', Phys. Rev. D Part. Fields Gravit. Cosmol. 78, 065013 (2008);e-print arXiv:hep-th/0805.0602] are analyzed in detail.

Polygons, Pillars and Pavilions: Discovering Connections between Geometry and Architecture

Science.gov (United States)

Madden, Sean Patrick

2017-01-01

Crowning the second semester of geometry, taught within a Catholic middle school, the author's students explored connections between the geometry of regular polygons and architecture of local buildings. They went on to explore how these principles apply famous buildings around the world such as the monuments of Washington, D.C. and the elliptical…

Polygons and Their Circles

Science.gov (United States)

Stephenson, Paul

2009-01-01

In order to find its circumference, Archimedes famously boxed the circle between two polygons. Ending the first of a series of articles (MT179) with an aside, Francis Lopez-Real reverses the situation to ask: Which polygons can be boxed between two circles? (The official term for such polygons is "bicentric".) The sides of these polygons are…

Ensemble Kalman filter regularization using leave-one-out data cross-validation

KAUST Repository

Rayo Schiappacasse, Lautaro Jerónimo

2012-09-19

In this work, the classical leave-one-out cross-validation method for selecting a regularization parameter for the Tikhonov problem is implemented within the EnKF framework. Following the original concept, the regularization parameter is selected such that it minimizes the predictive error. Some ideas about the implementation, suitability and conceptual interest of the method are discussed. Finally, what will be called the data cross-validation regularized EnKF (dCVr-EnKF) is implemented in a 2D 2-phase synthetic oil reservoir experiment and the results analyzed.

Zernike-like systems in polygons and polygonal facets.

Science.gov (United States)

Ferreira, Chelo; López, José L; Navarro, Rafael; Sinusía, Ester Pérez

2015-07-20

Zernike polynomials are commonly used to represent the wavefront phase on circular optical apertures, since they form a complete and orthonormal basis on the unit disk. In [Opt. Lett.32, 74 (2007)10.1364/OL.32.000074OPLEDP0146-9592] we introduced a new Zernike basis for elliptic and annular optical apertures based on an appropriate diffeomorphism between the unit disk and the ellipse and the annulus. Here, we present a generalization of this Zernike basis for a variety of important optical apertures, paying special attention to polygons and the polygonal facets present in segmented mirror telescopes. On the contrary to ad hoc solutions, most of them based on the Gram-Smith orthonormalization method, here we consider a piecewise diffeomorphism that transforms the unit disk into the polygon under consideration. We use this mapping to define a Zernike-like orthonormal system over the polygon. We also consider ensembles of polygonal facets that are essential in the design of segmented mirror telescopes. This generalization, based on in-plane warping of the basis functions, provides a unique solution, and what is more important, it guarantees a reasonable level of invariance of the mathematical properties and the physical meaning of the initial basis functions. Both the general form and the explicit expressions for a typical example of telescope optical aperture are provided.

Null polygonal Wilson loops and minimal surfaces in Anti-de-Sitter space

International Nuclear Information System (INIS)

Alday, Luis F.; Maldacena, Juan

2009-01-01

We consider minimal surfaces in three dimensional anti-de-Sitter space that end at the AdS boundary on a polygon given by a sequence of null segments. The problem can be reduced to a certain generalized Sinh-Gordon equation and to SU(2) Hitchin equations. We describe in detail the mathematical problem that needs to be solved. This problem is mathematically the same as the one studied by Gaiotto, Moore and Neitzke in the context of the moduli space of certain supersymmetric theories. Using their results we can find the explicit answer for the area of a surface that ends on an eight-sided polygon. Via the gauge/gravity duality this can also be interpreted as a certain eight-gluon scattering amplitude at strong coupling. In addition, we give fairly explicit solutions for regular polygons.

Measurements of the effective thermal neutron absorption cross-section in multi-grain models

International Nuclear Information System (INIS)

Drozdowicz, K.; Gabanska, B.; Igielski, A.; Krynicka, E.; Schneider, K.; Woznicka, U.

2005-01-01

The effective macroscopic absorption cross-section Σ a eff of thermal neutrons in a grained medium differs from the corresponding cross-section Σ a hom in the homogeneous medium consisting of the same components, contributing in the same amounts. The ratio of these cross-sections defines the grain parameter, G, which is a measure of heterogeneity of the system for neutron absorption. Heterogeneous models have been built as two- or three-component systems (Ag, Cu and Co 3 O 4 grains distributed in a regular grid in Plexiglas, in various proportions between them). The effective absorption cross-section has been measured and the experimental grain parameter has been found for each model. The obtained values are in the interval 0.34 < G < 0.58, while G = 1 means the homogeneous material. (author)

Statistical Model Analysis of (n, α Cross Sections for 4.0-6.5 MeV Neutrons

Directory of Open Access Journals (Sweden)

Khuukhenkhuu G.

2016-01-01

Full Text Available The statistical model based on the Weisskopf-Ewing theory and constant nuclear temperature approximation is used for systematical analysis of the 4.0-6.5 MeV neutron induced (n, α reaction cross sections. The α-clusterization effect was considered in the (n, α cross sections. A certain dependence of the (n, α cross sections on the relative neutron excess parameter of the target nuclei was observed. The systematic regularity of the (n, α cross sections behaviour is useful to estimate the same reaction cross sections for unstable isotopes. The results of our analysis can be used for nuclear astrophysical calculations such as helium burning and possible branching in the s-process.

Generalized polygons

CERN Document Server

Maldeghem, Hendrik

1998-01-01

This book is intended to be an introduction to the fascinating theory ofgeneralized polygons for both the graduate student and the specialized researcher in the field. It gathers together a lot of basic properties (some of which are usually referred to in research papers as belonging to folklore) and very recent and sometimes deep results. I have chosen a fairly strict geometrical approach, which requires some knowledge of basic projective geometry. Yet, it enables one to prove some typically group-theoretical results such as the determination of the automorphism groups of certain Moufang polygons. As such, some basic group-theoretical knowledge is required of the reader. The notion of a generalized polygon is a relatively recent one. But it is one of the most important concepts in incidence geometry. Generalized polygons are the building bricks of Tits buildings. They are the prototypes and precursors of more general geometries such as partial geometries, partial quadrangles, semi-partial ge­ ometries, near...

Generalized polygons

CERN Document Server

Van Maldeghem, Hendrik

1998-01-01

Generalized Polygons is the first book to cover, in a coherent manner, the theory of polygons from scratch. In particular, it fills elementary gaps in the literature and gives an up-to-date account of current research in this area, including most proofs, which are often unified and streamlined in comparison to the versions generally known. Generalized Polygons will be welcomed both by the student seeking an introduction to the subject as well as the researcher who will value the work as a reference. In particular, it will be of great value for specialists working in the field of generalized polygons (which are, incidentally, the rank 2 Tits-buildings) or in fields directly related to Tits-buildings, incidence geometry and finite geometry. The approach taken in the book is of geometric nature, but algebraic results are included and proven (in a geometric way!). A noteworthy feature is that the book unifies and generalizes notions, definitions and results that exist for quadrangles, hexagons, octagons - in the ...

Origin of giant Martian polygons

Science.gov (United States)

Mcgill, George E.; Hills, L. S.

1992-01-01

Extensive areas of the Martian northern plains in Utopia and Acidalia planitiae are characterized by 'polygonal terrane'. Polygonal terrane consists of material cut by complex troughs defining a pattern resembling mudcracks, columnar joints, or frost-wedge polygons on earth. However, the Martian polygons are orders of magnitude larger than these potential earth analogues, leading to severe mechanical difficulties for genetic models based on simple analogy arguments. Plate-bending and finite element models indicate that shrinkage of desiccating sediment or cooling volcanics accompanied by differential compaction over buried topography can account for the stresses responsible for polygon troughs as well as the large size of the polygons. Although trough widths and depths relate primarily to shrinkage, the large scale of the polygonl pattern relates to the spacing between topographic elevations on the surface buried beneath polygonal terrane material. Geological relationships favor a sedimentary origin for polygonal terrane material, but our model is not dependent on the specific genesis. Our analysis also suggests that the polygons must have formed at a geologically rapid rate.

High Latitude Polygons

Science.gov (United States)

2005-01-01

26 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows polygonal patterned ground on a south high-latitude plain. The outlines of the polygons, like the craters and hills in this region, are somewhat enhanced by the presence of bright frost left over from the previous winter. On Earth, polygons at high latitudes would usually be attributed to the seasonal freezing and thawing cycles of ground ice. The origin of similar polygons on Mars is less certain, but might also be an indicator of ground ice. Location near: 75.3oS, 113.2oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

Knotting in stretched polygons

International Nuclear Information System (INIS)

Rensburg, E J Janse van; Orlandini, E; Tesi, M C; Whittington, S G

2008-01-01

The knotting in a lattice polygon model of ring polymers is examined when a stretching force is applied to the polygon. By examining the incidence of cut-planes in the polygon, we prove a pattern theorem in the stretching regime for large applied forces. This theorem can be used to examine the incidence of entanglements such as knotting and writhing. In particular, we prove that for arbitrarily large positive, but finite, values of the stretching force, the probability that a stretched polygon is knotted approaches 1 as the length of the polygon increases. In the case of writhing, we prove that for stretched polygons of length n, and for every function f(n)=o(√n), the probability that the absolute value of the mean writhe is less than f(n) approaches 0 as n → ∞, for sufficiently large values of the applied stretching force

Ensemble Kalman filter regularization using leave-one-out data cross-validation

KAUST Repository

Rayo Schiappacasse, Lautaro Jeró nimo; Hoteit, Ibrahim

2012-01-01

In this work, the classical leave-one-out cross-validation method for selecting a regularization parameter for the Tikhonov problem is implemented within the EnKF framework. Following the original concept, the regularization parameter is selected

Finding the Most Uniform Changes in Vowel Polygon Caused by Psychological Stress

Directory of Open Access Journals (Sweden)

M. Stanek

2015-06-01

Full Text Available Using vowel polygons, exactly their parameters, is chosen as the criterion for achievement of differences between normal state of speaker and relevant speech under real psychological stress. All results were experimentally obtained by created software for vowel polygon analysis applied on ExamStress database. Selected 6 methods based on cross-correlation of different features were classified by the coefficient of variation and for each individual vowel polygon, the efficiency coefficient marking the most significant and uniform differences between stressed and normal speech were calculated. As the best method for observing generated differences resulted method considered mean of cross correlation values received for difference area value with vector length and angle parameter couples. Generally, best results for stress detection are achieved by vowel triangles created by /i/-/o/-/u/ and /a/-/i/-/o/ vowel triangles in formant planes containing the fifth formant F5 combined with other formants.

Determination of Optimum Cross-section for Oran Highway Revetment

Science.gov (United States)

Velioglu, Deniz; Sogut, Erdinc; Guler, Isikhan

2017-04-01

Revetments are shore parallel, sloping coastal structures which are built to provide protection from the negative effects of the sea. The revetment mentioned in this study is located in the City of Oran, Algeria and is currently under construction. This study investigates the determination of the optimum revetment cross section for Oran highway, considering both the hydraulic stability of the revetment and economy. The existence of cliffs in the region and the settlement of the City of Oran created a necessity to re-align Oran highway; therefore, it was shifted towards the Gulf of Oran. Approximately 1 km of the highway is to be constructed on the Mediterranean Sea due to the new alignment. In order to protect the sea side of the road from the adverse effects of the sea, a revetment was designed. The proposed cross section had an armour layer composed of 23 tons of antifer units and regular placement of armour units was recommended. In order to check the hydraulic stability of the proposed section, physical model tests were performed in the laboratory of LEM (Laboratoire d'Etudes Maritimes) in Algeria, using the pre-determined design wave conditions. The physical model tests revealed that the trunk of the revetment was totaly damaged. Accordingly, the proposed section was found insufficient and certain modifications were required. The first modification was made in the arrangement of armour units, changing them from regular to irregular. After testing the new cross section, it was observed that the revetment was vulnerable to breaking wave attack due to the toe geometry and thus the toe of the revetment had to be re-shaped. Therefore, the second option was to reduce the toe elevation. It was observed that even though the revetment trunk was safe, the damage in the toe was not in acceptable limits. The new cross section was found insufficient and as the final option, the weight of the antifer units used in the armour layer was increased, the toe length of the

Area of Lattice Polygons

Science.gov (United States)

Scott, Paul

2006-01-01

A lattice is a (rectangular) grid of points, usually pictured as occurring at the intersections of two orthogonal sets of parallel, equally spaced lines. Polygons that have lattice points as vertices are called lattice polygons. It is clear that lattice polygons come in various shapes and sizes. A very small lattice triangle may cover just 3…

Ab initio density functional theory investigation of crystalline bundles of polygonized single-walled silicon carbide nanotubes

Energy Technology Data Exchange (ETDEWEB)

Moradian, Rostam; Behzad, Somayeh; Chegel, Raad [Physics Department, Faculty of Science, Razi University, Kermanshah (Iran, Islamic Republic of)], E-mail: moradian.rostam@gmail.com

2008-11-19

By using ab initio density functional theory, the structural characterizations and electronic properties of two large-diameter (13, 13) and (14, 14) armchair silicon carbide nanotube (SiCNT) bundles are investigated. Full structural optimizations show that the cross sections of these large-diameter SiCNTs in the bundles have a nearly hexagonal shape. The effects of inter-tube coupling on the electronic dispersions of large-diameter SiCNT bundles are demonstrated. By comparing the band structures of the triangular lattices of (14, 14) SiCNTs with nearly hexagonal and circular cross sections we found that the polygonization of the tubes in the bundle leads to a further dispersion of the occupied bands and an increase in the bandgap by 0.18 eV.

Ab initio density functional theory investigation of crystalline bundles of polygonized single-walled silicon carbide nanotubes

International Nuclear Information System (INIS)

Moradian, Rostam; Behzad, Somayeh; Chegel, Raad

2008-01-01

By using ab initio density functional theory, the structural characterizations and electronic properties of two large-diameter (13, 13) and (14, 14) armchair silicon carbide nanotube (SiCNT) bundles are investigated. Full structural optimizations show that the cross sections of these large-diameter SiCNTs in the bundles have a nearly hexagonal shape. The effects of inter-tube coupling on the electronic dispersions of large-diameter SiCNT bundles are demonstrated. By comparing the band structures of the triangular lattices of (14, 14) SiCNTs with nearly hexagonal and circular cross sections we found that the polygonization of the tubes in the bundle leads to a further dispersion of the occupied bands and an increase in the bandgap by 0.18 eV.

Ab initio density functional theory investigation of crystalline bundles of polygonized single-walled silicon carbide nanotubes

Science.gov (United States)

Moradian, Rostam; Behzad, Somayeh; Chegel, Raad

2008-11-01

By using ab initio density functional theory, the structural characterizations and electronic properties of two large-diameter (13, 13) and (14, 14) armchair silicon carbide nanotube (SiCNT) bundles are investigated. Full structural optimizations show that the cross sections of these large-diameter SiCNTs in the bundles have a nearly hexagonal shape. The effects of inter-tube coupling on the electronic dispersions of large-diameter SiCNT bundles are demonstrated. By comparing the band structures of the triangular lattices of (14, 14) SiCNTs with nearly hexagonal and circular cross sections we found that the polygonization of the tubes in the bundle leads to a further dispersion of the occupied bands and an increase in the bandgap by 0.18 eV.

Frosty Polygons

Science.gov (United States)

2004-01-01

16 January 2004 Looking somewhat like a roadmap, this 3 km (1.9 mi) wide view of a cratered plain in the martian south polar region shows a plethora of cracks that form polygonal patterns. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is located near 78.9oS, 357.3oW. Polygons such as these, where they are found on Earth, would be indicators of the presence of subsurface ice. Whether the same is true for Mars is uncertain. What is certain is that modern, seasonal frost on the surface enhances the appearance of the polygons as the frost persists longer in the cracks than on adjacent plains. This southern springtime image is illuminated by sunlight from the upper left.

Flow in curved ducts of varying cross-section

Science.gov (United States)

Sotiropoulos, F.; Patel, V. C.

1992-07-01

Two numerical methods for solving the incompressible Navier-Stokes equations are compared with each other by applying them to calculate laminar and turbulent flows through curved ducts of regular cross-section. Detailed comparisons, between the computed solutions and experimental data, are carried out in order to validate the two methods and to identify their relative merits and disadvantages. Based on the conclusions of this comparative study a numerical method is developed for simulating viscous flows through curved ducts of varying cross-sections. The proposed method is capable of simulating the near-wall turbulence using fine computational meshes across the sublayer in conjunction with a two-layer k-epsilon model. Numerical solutions are obtained for: (1) a straight transition duct geometry, and (2) a hydroturbine draft-tube configuration at model scale Reynolds number for various inlet swirl intensities. The report also provides a detailed literature survey that summarizes all the experimental and computational work in the area of duct flows.

Small-scale polygons on Mars

Science.gov (United States)

Lucchitta, B. K.

1984-01-01

Polygonal-fracture patterns on the martian surface were discovered on Viking Orbiter images. The polygons are 2-20 km in diameter, much larger than those of known patterned ground on Earth. New observations show, however, that polygons exist on Mars that have diameters similar to those of ice-wedge polygons on Earth (generally a few meters to more than 100 m). Various explanations for the origin of these crustal features are examined; seasonal desiccation and thermal-contraction cracking in ice-rich ground. It is difficult to ascertain whether the polygons are forming today or are relics from the past. The crispness of some crack suggests a recent origin. On the other hand the absence of upturned edges (indicating actively forming ice wedges), the locally disintegrating ground, and a few possible superposed rayed craters indicate that the polygons are not forming at the present.

Standard cross-section data

International Nuclear Information System (INIS)

Carlson, A.D.

1984-01-01

The accuracy of neutron cross-section measurement is limited by the uncertainty in the standard cross-section and the errors associated with using it. Any improvement in the standard immediately improves all cross-section measurements which have been made relative to that standard. Light element, capture and fission standards are discussed. (U.K.)

Calculus domains modelled using an original bool algebra based on polygons

Science.gov (United States)

Oanta, E.; Panait, C.; Raicu, A.; Barhalescu, M.; Axinte, T.

2016-08-01

Analytical and numerical computer based models require analytical definitions of the calculus domains. The paper presents a method to model a calculus domain based on a bool algebra which uses solid and hollow polygons. The general calculus relations of the geometrical characteristics that are widely used in mechanical engineering are tested using several shapes of the calculus domain in order to draw conclusions regarding the most effective methods to discretize the domain. The paper also tests the results of several CAD commercial software applications which are able to compute the geometrical characteristics, being drawn interesting conclusions. The tests were also targeting the accuracy of the results vs. the number of nodes on the curved boundary of the cross section. The study required the development of an original software consisting of more than 1700 computer code lines. In comparison with other calculus methods, the discretization using convex polygons is a simpler approach. Moreover, this method doesn't lead to large numbers as the spline approximation did, in that case being required special software packages in order to offer multiple, arbitrary precision. The knowledge resulted from this study may be used to develop complex computer based models in engineering.

On the Significance of the Upcoming Large Hadron Collider Proton-Proton Cross Section Data

Directory of Open Access Journals (Sweden)

Comay E.

2010-04-01

Full Text Available The relevance of the Regular Charge-Monopole Theory to the proton structure is described. The discussion relies on classicalelectrodynamics and its associated quantum mechanics. Few experimental data are used as a clue to the specific structure of baryons. This basis provides an explanation for the shape of the graph of the pre-LHC proton-proton cross section data. These data also enable a description of the significance of the expected LHC cross section measurements which will be known soon. Problematic QCD issues are pointed out.

Rotating Polygons on a Fluid Surface

DEFF Research Database (Denmark)

Bohr, Tomas; Jansson, Thomas; Haspang, Martin

spontaneously and the surface can take the shape of a rigidly rotating polygon. With water we have observed polygons with up to 6 corners. The rotation speed of the polygons does not coincide with that of the plate, but it is often mode-locked, such that the polygon rotates by one corner for each complete...... and R. Miraghaie, ”Symmetry breaking in free-surface cylinder flows”, J. Fluid Mech., 502, 99 (2004)). The polygons occur at much larger Reynolds numbers, for water around 500.000. Correspondingly, the dependence on viscosity is rather small....

Total curvature and total torsion of knotted random polygons in confinement

Science.gov (United States)

Diao, Yuanan; Ernst, Claus; Rawdon, Eric J.; Ziegler, Uta

2018-04-01

Knots in nature are typically confined spatially. The confinement affects the possible configurations, which in turn affects the spectrum of possible knot types as well as the geometry of the configurations within each knot type. The goal of this paper is to determine how confinement, length, and knotting affect the total curvature and total torsion of random polygons. Previously published papers have investigated these effects in the unconstrained case. In particular, we analyze how the total curvature and total torsion are affected by (1) varying the length of polygons within a fixed confinement radius and (2) varying the confinement radius of polygons with a fixed length. We also compare the total curvature and total torsion of groups of knots with similar complexity (measured as crossing number). While some of our results fall in line with what has been observed in the studies of the unconfined random polygons, a few surprising results emerge from our study, showing some properties that are unique due to the effect of knotting in confinement.

Cross sections for atmospheric corrections

International Nuclear Information System (INIS)

Meyer, J.P.; Casse, M.; Westergaard, N.

1975-01-01

A set of cross sections for spallation of relativistic nuclei is proposed based on (i) the best available proton cross sections, (ii) an extrapolation to heavier nuclei of the dependence on the number of nucleons lost of the 'target factor' observed for C 12 and O 16 by Lindstrom et al. (1975), in analogy with Rudstam's formalism, and (iii) on a normalization of all cross sections to the total cross sections for production of fragments with Asub(f) >= 6. The obtained cross sections for peripheral interactions are not inconsistent with simple geometrical considerations. (orig.) [de

Polar Polygons

Science.gov (United States)

2005-01-01

18 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark-outlined polygons on a frost-covered surface in the south polar region of Mars. In summer, this surface would not be bright and the polygons would not have dark outlines--these are a product of the presence of seasonal frost. Location near: 77.2oS, 204.8oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

Verbal Working Memory Is Related to the Acquisition of Cross-Linguistic Phonological Regularities.

Science.gov (United States)

Bosma, Evelyn; Heeringa, Wilbert; Hoekstra, Eric; Versloot, Arjen; Blom, Elma

2017-01-01

Closely related languages share cross-linguistic phonological regularities, such as Frisian -âld [ͻ:t] and Dutch -oud [ʱut], as in the cognate pairs kâld [kͻ:t] - koud [kʱut] 'cold' and wâld [wͻ:t] - woud [wʱut] 'forest'. Within Bybee's (1995, 2001, 2008, 2010) network model, these regularities are, just like grammatical rules within a language, generalizations that emerge from schemas of phonologically and semantically related words. Previous research has shown that verbal working memory is related to the acquisition of grammar, but not vocabulary. This suggests that verbal working memory supports the acquisition of linguistic regularities. In order to test this hypothesis we investigated whether verbal working memory is also related to the acquisition of cross-linguistic phonological regularities. For three consecutive years, 5- to 8-year-old Frisian-Dutch bilingual children ( n = 120) were tested annually on verbal working memory and a Frisian receptive vocabulary task that comprised four cognate categories: (1) identical cognates, (2) non-identical cognates that either do or (3) do not exhibit a phonological regularity between Frisian and Dutch, and (4) non-cognates. The results showed that verbal working memory had a significantly stronger effect on cognate category (2) than on the other three cognate categories. This suggests that verbal working memory is related to the acquisition of cross-linguistic phonological regularities. More generally, it confirms the hypothesis that verbal working memory plays a role in the acquisition of linguistic regularities.

A polygonal nodal SP3 method for whole core Pin-by-Pin neutronics calculation

Energy Technology Data Exchange (ETDEWEB)

Li, Yunzhao; Wu, Hongchun; Cao, Liangzhi, E-mail: xjtulyz@gmail.com, E-mail: hongchun@mail.xjtu.edu.cn, E-mail: caolz@mail.xjtu.edu.cn [School of Nuclear Science and Technology, Xi' an Jiaotong University, Shaanxi (China)

2011-07-01

In this polygonal nodal-SP3 method, neutron transport equation is transformed by employing an isotropic SP3 method into two coupled equations that are both in the same mathematic form with the diffusion equation, and then a polygonal nodal method is proposed to solve the two coupled equations. In the polygonal nodal method, adjacent nodes are coupled through partial currents, and a nodal response matrix between incoming and outgoing currents is obtained by expanding detailed nodal flux distribution into a sum of exponential functions. This method avoids the transverse integral technique, which is widely used in regular nodal method and can not be used in triangular geometry because of the mathematical singularity. It is demonstrated by the numerical results of the test problems that the k{sub eff} and power distribution agree well with other codes, the triangular nodal-SP3 method appears faster, and that whole core pin-by-pin transport calculation with fine meshes is feasible after parallelization and acceleration. (author)

Multitrajectory eikonal cross sections

International Nuclear Information System (INIS)

Turner, R.E.

1983-01-01

With the use of reference and distorted transition operators, a time-correlation-function representation of the inelastic differential cross section has recently been used to obtain distorted eikonal cross sections. These cross sections involve straight-line and reference classical translational trajectories that are unaffected by any internal-state changes which have occurred during the collision. This distorted eikonal theory is now extended to include effects of internal-state changes on the translational motion. In particular, a different classical trajectory is associated with each pair of internal states. Expressions for these inelastic cross sections are obtained in terms of time-ordered cosine and sine memory functions using the Zwanzig-Feshbach projection-operator method. Explicit formulas are obtained in the time-disordered perturbation approximation

Stretched polygons in a lattice tube

Energy Technology Data Exchange (ETDEWEB)

Atapour, M [Department of Mathematics and Statistics, York University, Toronto, ON M3J 1P3 (Canada); Soteros, C E [Department of Mathematics and Statistics, University of Saskatchewan, Saskatoon, SK S7N 5E6 (Canada); Whittington, S G [Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6 (Canada)], E-mail: atapour@mathstat.yorku.ca, E-mail: soteros@math.usask.ca, E-mail: swhittin@chem.utoronto.ca

2009-08-14

We examine the topological entanglements of polygons confined to a lattice tube and under the influence of an external tensile force f. The existence of the limiting free energy for these so-called stretched polygons is proved and then, using transfer matrix arguments, a pattern theorem for stretched polygons is proved. Note that the tube constraint allows us to prove a pattern theorem for any arbitrary value of f, while without the tube constraint it has so far only been proved for large values of f. The stretched polygon pattern theorem is used first to show that the average span per edge of a randomly chosen n-edge stretched polygon approaches a positive value, non-decreasing in f, as n {yields} {infinity}. We then show that the knotting probability of an n-edge stretched polygon confined to a tube goes to one exponentially as n {yields} {infinity}. Thus as n {yields} {infinity} when polygons are influenced by a force f, no matter its strength or direction, topological entanglements, as defined by knotting, occur with high probability. (fast track communication)

Stretched polygons in a lattice tube

International Nuclear Information System (INIS)

Atapour, M; Soteros, C E; Whittington, S G

2009-01-01

We examine the topological entanglements of polygons confined to a lattice tube and under the influence of an external tensile force f. The existence of the limiting free energy for these so-called stretched polygons is proved and then, using transfer matrix arguments, a pattern theorem for stretched polygons is proved. Note that the tube constraint allows us to prove a pattern theorem for any arbitrary value of f, while without the tube constraint it has so far only been proved for large values of f. The stretched polygon pattern theorem is used first to show that the average span per edge of a randomly chosen n-edge stretched polygon approaches a positive value, non-decreasing in f, as n → ∞. We then show that the knotting probability of an n-edge stretched polygon confined to a tube goes to one exponentially as n → ∞. Thus as n → ∞ when polygons are influenced by a force f, no matter its strength or direction, topological entanglements, as defined by knotting, occur with high probability. (fast track communication)

Evolution of the regions of the 3D particle motion in the regular polygon problem of (N+1) bodies with a quasi-homogeneous potential

Science.gov (United States)

Fakis, Demetrios; Kalvouridis, Tilemahos

2017-09-01

The regular polygon problem of (N+1) bodies deals with the dynamics of a small body, natural or artificial, in the force field of N big bodies, the ν=N-1 of which have equal masses and form an imaginary regular ν -gon, while the Nth body with a different mass is located at the center of mass of the system. In this work, instead of considering Newtonian potentials and forces, we assume that the big bodies create quasi-homogeneous potentials, in the sense that we insert to the inverse square Newtonian law of gravitation an inverse cube corrective term, aiming to approximate various phenomena due to their shape or to the radiation emitting from the primaries. Based on this new consideration, we apply a general methodology in order to investigate by means of the zero-velocity surfaces, the regions where 3D motions of the small body are allowed, their evolutions and parametric variations, their topological bifurcations, as well as the existing trapping domains of the particle. Here we note that this process is definitely a fundamental step of great importance in the study of many dynamical systems characterized by a Jacobian-type integral of motion in the long way of searching for solutions of any kind.

FEMA DFIRM Cross Sections

Data.gov (United States)

Minnesota Department of Natural Resources — FEMA Cross Sections are required for any Digital Flood Insurance Rate Map database where cross sections are shown on the Flood Insurance Rate Map (FIRM). Normally...

Verbal Working Memory Is Related to the Acquisition of Cross-Linguistic Phonological Regularities

Directory of Open Access Journals (Sweden)

Evelyn Bosma

2017-09-01

Full Text Available Closely related languages share cross-linguistic phonological regularities, such as Frisian -âld [ͻ:t] and Dutch -oud [ʱut], as in the cognate pairs kâld [kͻ:t] – koud [kʱut] ‘cold’ and wâld [wͻ:t] – woud [wʱut] ‘forest’. Within Bybee’s (1995, 2001, 2008, 2010 network model, these regularities are, just like grammatical rules within a language, generalizations that emerge from schemas of phonologically and semantically related words. Previous research has shown that verbal working memory is related to the acquisition of grammar, but not vocabulary. This suggests that verbal working memory supports the acquisition of linguistic regularities. In order to test this hypothesis we investigated whether verbal working memory is also related to the acquisition of cross-linguistic phonological regularities. For three consecutive years, 5- to 8-year-old Frisian-Dutch bilingual children (n = 120 were tested annually on verbal working memory and a Frisian receptive vocabulary task that comprised four cognate categories: (1 identical cognates, (2 non-identical cognates that either do or (3 do not exhibit a phonological regularity between Frisian and Dutch, and (4 non-cognates. The results showed that verbal working memory had a significantly stronger effect on cognate category (2 than on the other three cognate categories. This suggests that verbal working memory is related to the acquisition of cross-linguistic phonological regularities. More generally, it confirms the hypothesis that verbal working memory plays a role in the acquisition of linguistic regularities.

Precise algorithm to generate random sequential adsorption of hard polygons at saturation

Science.gov (United States)

Zhang, G.

2018-04-01

Random sequential adsorption (RSA) is a time-dependent packing process, in which particles of certain shapes are randomly and sequentially placed into an empty space without overlap. In the infinite-time limit, the density approaches a "saturation" limit. Although this limit has attracted particular research interest, the majority of past studies could only probe this limit by extrapolation. We have previously found an algorithm to reach this limit using finite computational time for spherical particles and could thus determine the saturation density of spheres with high accuracy. In this paper, we generalize this algorithm to generate saturated RSA packings of two-dimensional polygons. We also calculate the saturation density for regular polygons of three to ten sides and obtain results that are consistent with previous, extrapolation-based studies.

On the Significance of the Upcoming Large Hadron Collider Proton-Proton Cross Section Data

Directory of Open Access Journals (Sweden)

Comay E.

2010-04-01

Full Text Available The relevance of the Regular Charge-Monopole Theory to the proton structure is de- scribed. The discussion relies on classical electrodynamics and its associated quantum mechanics. Few experimental data are used as a clue to the specific structure of baryons. This basis provides an explanation for the shape of the graph of the pre-LHC proton- proton cross section data. These data also enable a description of the significance of the expected LHC cross section measurements which will be known soon. Problematic QCD issues are pointed out.

Regularized unfolding of jet cross sections in deep-inelastic ep scattering at HERA and determination of the strong coupling constant

International Nuclear Information System (INIS)

Britzger, Daniel Andreas

2013-10-01

In this thesis double-differential cross sections for jet production in neutral current deep-inelastic e ± p scattering (DIS) are presented at the center-of-mass energy of √(s)=319 GeV, and in the kinematic range of the squared four-momentum transfer 150 2 2 and the inelasticity 0.2 T -algorithm and are constrained to the pseudorapidity range -1.0 lab jet T jet T jet s (M Z ) at the scale of the mass of the Z 0 boson in the framework of perturbative quantum chromodynamics in next-to-leading order. Values are derived separately for the absolute and normalized jet cross section measurements. A higher sensitivity to α s (M Z ) is obtained in a simultaneous least-square-minimization procedure to the three jet cross sections, taking the statistical correlations and correlations due to other experimental uncertainties into account. The most precise value is obtained from all normalized jet cross sections, yielding α s (M Z )=0.1165±0.0008, which benefits from the high statistical precision of the inclusive jet measurement, the increased sensitivity to α s (M Z ) of the trijet cross section, and from the cancellation of normalization uncertainties. However, the value of the strong coupling constant is currently only determinable from this measurement with a precision of 3 to 4% due to the limited precision of the theoretical predictions at next-to-leading order.

The investigation of the elastic photon scattering cross sections by copper atoms and ions

International Nuclear Information System (INIS)

Kuplyauskene, A.B.

1976-01-01

The differential cross sections of coherent scattering of photons on a copper atom and ions Cu + and Cu 2+ and also on ions Zn + and Ga 2+ in their ground states have been studied theoretically. The energy of an incident photon has varied in the range from 0.5 keV to 200 keV, and the scattering cross sections are given for angles of 30 deg, 60 deg, 90 deg, 120 deg, 150 deg. The calculations are performed in the formfactor approximation with the use of generalized hydrogen-like analytical radial orbitals. To clarify the contribution from individual shells the cross sections of photon scattering on individual electron of shells are calculated. It follows from the calculations that when the energies of the incident photon are less than 4 keV, the main contribution into the differential cross section is made by external electrons. Then, alongside with the increase of the energy, the contribution of the electrons decreases, and the inner shells begin to play a more important role. Therefore the photon cross sections for the energies greater than 50 keV practically coincide for atoms and ions of copper. The general regularities of the cross section variation accompanying the increase of the photon energy are similar for all the elements under study. The angular dependences of cross sections are such that they decrease first and after reaching the minimum at angles of 90 deg - 120 deg increase again

The effects of workplace flexibility on health behaviors: a cross-sectional and longitudinal analysis.

Science.gov (United States)

Grzywacz, Joseph G; Casey, Patrick R; Jones, Fiona A

2007-12-01

To examine the cross-sectional and longitudinal associations between workplace flexibility and health behaviors, and estimate the potential importance of flexibility for effective worksite health promotion programs. Cross-sectional and longitudinal health risk appraisal data were obtained from US based employees of a multinational pharmaceutical company (n = 3193). Examined health behaviors were hours of sleep, physical activity frequency, health education seminar attendance, frequency of practicing personal resilience techniques, and self-appraised lifestyle. Self-reported flexibility in the workplace was the primary independent variable. Each health behavior, except regular attendance in health education seminars, was positively related to perceived flexibility in cross-sectional analyses. Sleep and self-appraised lifestyle were significantly related to changes in perceived flexibility over time. Workplace flexibility may contribute to positive lifestyle behaviors, and may play an important role in effective worksite health promotion programs.

Comparison of integral cross section values of several cross section libraries in the SAND-II format

International Nuclear Information System (INIS)

Zijp, W.L.; Nolthenius, H.J.

1976-09-01

A comparison of some integral cross-section values for several cross-section libraries in the SAND-II format is presented. The integral cross-section values are calculated with the aid of the spectrum functions for a Watt fission spectrum, a 1/E spectrum and a Maxwellian spectrum. The libraries which are considered here are CCC-112B, ENDF/B-IV, DETAN74, LAPENAS and CESNEF. These 5 cross-section libraries used have all the SAND-II format. Discrepancies between cross-sections in the different libraries are indicated but not discussed

Polygons near Lyot Crater

Science.gov (United States)

2003-01-01

MGS MOC Release No. MOC2-564, 4 December 2003This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows patterned ground, arranged in the form of polygons, on the undulating plains associated with ejecta from the Lyot impact crater on the martian northern plains. This picture was acquired in October 2003 and shows that the polygon margins are ridges with large boulders--shown here as dark dots--on them. On Earth, polygon patterns like this are created in arctic and antarctic regions where there is ice in the ground. The seasonal and longer-term cycles of freezing and thawing of the ice-rich ground cause these features to form over time. Whether the same is true for Mars is unknown. The polygons are located near 54.6oN, 326.6oW. The image covers an area 3 km (1.9 mi) wide and is illuminated from the lower left.

Analytical algorithm for the generation of polygonal projection data for tomographic reconstruction

International Nuclear Information System (INIS)

Davis, G.R.

1996-01-01

Tomographic reconstruction algorithms and filters can be tested using a mathematical phantom, that is, a computer program which takes numerical data as its input and outputs derived projection data. The input data is usually in the form of pixel ''densities'' over a regular grid, or position and dimensions of simple, geometrical objects. The former technique allows a greater variety of objects to be simulated, but is less suitable in the case when very small (relative to the ray-spacing) features are to be simulated. The second technique is normally used to simulate biological specimens, typically a human skull, modelled as a number of ellipses. This is not suitable for simulating non-biological specimens with features such as straight edges and fine cracks. We have therefore devised an algorithm for simulating objects described as a series of polygons. These polygons, or parts of them, may be smaller than the ray-spacing and there is no limit, except that imposed by computing resources, on the complexity, number or superposition of polygons. A simple test of such a phantom, reconstructed using the filtered back-projection method, revealed reconstruction artefacts not normally seen with ''biological'' phantoms. (orig.)

Tensor Product of Polygonal Cell Complexes

OpenAIRE

Chien, Yu-Yen

2017-01-01

We introduce the tensor product of polygonal cell complexes, which interacts nicely with the tensor product of link graphs of complexes. We also develop the unique factorization property of polygonal cell complexes with respect to the tensor product, and study the symmetries of tensor products of polygonal cell complexes.

Relativistic photon-Maxwellian electron cross sections

International Nuclear Information System (INIS)

Wienke, B.R.; Lathrop, B.L.; Devaney, J.J.

1986-01-01

Temperature corrected cross sections, complementing the Klein-Nishina set, are developed for astrophysical, plasma, and transport applications. The set is obtained from a nonlinear least squares fit to the exact photon-Maxwellian electron cross sections, using the static formula as the asymptotic basis. Two parameters are sufficient (two decimal places) to fit the exact cross sections over a range of 0-100 keV in electron temperature, and 0-1 MeV in incident photon energy. The fit is made to the total cross sections, yet the parameters predict both total and differential scattering cross sections well. Corresponding differential energy cross sections are less accurate. An extended fit to (just) the total cross sections, over the temperature and energy range 0-5 MeV, is also described. (author)

Homotopic Polygonal Line Simplification

DEFF Research Database (Denmark)

Deleuran, Lasse Kosetski

This thesis presents three contributions to the area of polygonal line simplification, or simply line simplification. A polygonal path, or simply a path is a list of points with line segments between the points. A path can be simplified by morphing it in order to minimize some objective function...

FEMA DFIRM Panel Scheme Polygons

Data.gov (United States)

Minnesota Department of Natural Resources — This layer contains information about the Flood Insurance Rate Map (FIRM) panel areas. The spatial entities representing FIRM panels are polygons. The polygon for...

Polygons on Crater Floor

Science.gov (United States)

2003-01-01

MGS MOC Release No. MOC2-357, 11 May 2003This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a pattern of polygons on the floor of a northern plains impact crater. These landforms are common on crater floors at high latitudes on Mars. Similar polygons occur in the arctic and antarctic regions of Earth, where they indicate the presence and freeze-thaw cycling of ground ice. Whether the polygons on Mars also indicate water ice in the ground is uncertain. The image is located in a crater at 64.8oN, 292.7oW. Sunlight illuminates the scene from the lower left.

Knotting probabilities after a local strand passage in unknotted self-avoiding polygons

International Nuclear Information System (INIS)

Szafron, M L; Soteros, C E

2011-01-01

We investigate, both theoretically and numerically, the knotting probabilities after a local strand passage is performed in an unknotted self-avoiding polygon (SAP) on the simple cubic lattice. In the polygons studied, it is assumed that two polygon segments have already been brought close together for the purpose of performing a strand passage. This restricts the polygons considered to those that contain a specific pattern called Θ at a fixed location; an unknotted polygon containing Θ is called a Θ-SAP. It is proved that the number of n-edge Θ-SAPs grows exponentially (with n) at the same rate as the total number of n-edge unknotted SAPs (those with no prespecified strand passage structure). Furthermore, it is proved that the same holds for subsets of n-edge Θ-SAPs that yield a specific after-strand-passage knot-type. Thus, the probability of a given after-strand-passage knot-type does not grow (or decay) exponentially with n. Instead, it is conjectured that these after-strand-passage knot probabilities approach, as n goes to infinity, knot-type dependent amplitude ratios lying strictly between 0 and 1. This conjecture is supported by numerical evidence from Monte Carlo data generated using a composite (aka multiple) Markov chain Monte Carlo BFACF algorithm developed to study Θ-SAPs. A new maximum likelihood method is used to estimate the critical exponents relevant to this conjecture. We also obtain strong numerical evidence that the after-strand-passage knotting probability depends on the local structure around the strand-passage site. If the local structure and the crossing sign at the strand-passage site are considered, then we observe that the more 'compact' the local structure, the less likely the after-strand-passage polygon is to be knotted. This trend for compactness versus knotting probability is consistent with results obtained for other strand-passage models; however, we are the first to note the influence of the crossing-sign information. We

Approximation algorithms for guarding holey polygons ...

African Journals Online (AJOL)

Guarding edges of polygons is a version of art gallery problem.The goal is finding the minimum number of guards to cover the edges of a polygon. This problem is NP-hard, and to our knowledge there are approximation algorithms just for simple polygons. In this paper we present two approximation algorithms for guarding ...

Integral nucleus-nucleus cross sections

International Nuclear Information System (INIS)

Barashenkov, V.S.; Kumawat, H.

2003-01-01

Expressions approximating the experimental integral cross sections for elastic and inelastic interactions of light and heavy nuclei at the energies up to several GeV/nucleon are presented. The calculated cross sections are inside the corridor of experimental errors or very close to it. Described in detail FORTRAN code and a numerical example of the cross section approximation are also presented

Photon-splitting cross sections

International Nuclear Information System (INIS)

Johannessen, A.M.; Mork, K.J.; Overbo, I.

1980-01-01

The differential cross section for photon splitting (scattering of one photon into two photons) in a Coulomb field, obtained earlier by Shima, has been integrated numerically to yield various differential cross sections. Energy spectra differential with respect to the energy of one of the outgoing photons are presented for several values of the primary photon energy. Selected examples of recoil momentum distributions and some interesting doubly or multiply differential cross sections are also given. Values for the total cross section are obtained essentially for all energies. The screening effect caused by atomic electrons is also taken into account, and is found to be important for high energies, as in e + e - pair production. Comparisons with various approximate results obtained by previous authors mostly show fair agreement. We also discuss the possibilities for experimental detection and find the most promising candidate to be a measurement of both photons, and their energies, at a moderately high energy

Comparison of integral cross section values of several cross section libraries in the SAND-II format

International Nuclear Information System (INIS)

Zijp, W.L.; Nolthenius, H.J.

1978-01-01

A comparison of some integral cross section values for several cross section libraries in the SAND-II format is presented. The integral cross section values are calculated with aid of the spectrum functions for a Watt fission spectrum, a 1/E spectrum and a Maxwellian spectrum. The libraries which are considered here are CCC-112B, ENDF/B-IV, DETAN74, LAPENAS and CESNEF. These 5 cross section libraries used have all the SAND-II format. (author)

Jet inclusive cross sections

International Nuclear Information System (INIS)

Del Duca, V.

1992-11-01

Minijet production in jet inclusive cross sections at hadron colliders, with large rapidity intervals between the tagged jets, is evaluated by using the BFKL pomeron. We describe the jet inclusive cross section for an arbitrary number of tagged jets, and show that it behaves like a system of coupled pomerons

Electron collision cross sections of mercury

International Nuclear Information System (INIS)

Suzuki, Susumu; Kuzuma, Kiyotaka; Itoh, Haruo

2006-01-01

In this paper, we propose a new collision cross section set for mercury which revises the original set summarized by Hayashi in 1989. Hanne reported three excitation collision cross sections (6 3 P 0 , 6 3 P 1 , 6 3 P 2 ) determined from an electron beam experiment in 1988. As a matter for regret, no attentive consideration was given to combining these three excitation cross sections with the cross section set of Hayashi. Therefore we propose a new set where these three excitation cross sections are included. In this study, other two excitation cross sections (6 1 P 1 , 6 3 D 3 ) except for the three excitation collision cross sections (6 3 P 0 , 6 3 P 1 , 6 3 P 2 ) are taken from the original set of Hayashi. The momentum transfer cross section and the ionization collision cross section are also taken from Hayashi. A Monte Carlo Simulation (MCS) technique is applied for evaluating our new cross section set. The present results of the electron drift velocity and the ionization coefficient are compared to experimental values. Agreement is secured in relation to the electron drift velocity for 1.5 Td 2 ) is the reduced electric field, E (V/cm) is the electric field, N (1/cm 3 ) is the number density of mercury atoms at 0degC, 1 Torr, E/N is also equal to 2.828 x 10 -17 E/p 0 from the relation of the ideal gas equation, p 0 (Torr) is gas pressure at 0degC, 1 Torr=1.33322 x 10 -2 N/cm -2 and 10 -17 V/cm 2 is called 1 Td. Thus it is ensured that our new cross section set is reasonable enough to be used up to 100 eV when considering with the electron drift velocity and the ionization coefficient. (author)

Background-cross-section-dependent subgroup parameters

International Nuclear Information System (INIS)

Yamamoto, Toshihisa

2003-01-01

A new set of subgroup parameters was derived that can reproduce the self-shielded cross section against a wide range of background cross sections. The subgroup parameters are expressed with a rational equation which numerator and denominator are expressed as the expansion series of background cross section, so that the background cross section dependence is exactly taken into account in the parameters. The advantage of the new subgroup parameters is that they can reproduce the self-shielded effect not only by group basis but also by subgroup basis. Then an adaptive method is also proposed which uses fitting procedure to evaluate the background-cross-section-dependence of the parameters. One of the simple fitting formula was able to reproduce the self-shielded subgroup cross section by less than 1% error from the precise evaluation. (author)

Cross-section methodology in SIMMER

International Nuclear Information System (INIS)

Soran, P.D.

1975-11-01

The cross-section methodology incorporated in the SIMMER code is described. Data base for all cross sections is the ENDF/B system with various progressing computer codes to group collapse and modify the group constants which are used in SIMMER. Either infinitely dilute cross sections or the Bondarenko formalism can be used in SIMMER. Presently only a microscopic treatment is considered, but preliminary macroscopic algorithms have been investigated

Cross-section methodology in SIMMER

International Nuclear Information System (INIS)

Soran, P.D.

1976-05-01

The cross-section methodology incorporated in the SIMMER code is described. Data base for all cross sections is the ENDF/B system with various progressing computer codes to group collapse and modify the group constants which are used in SIMMER. Either infinitely dilute cross sections or the Bondarenko formalism can be used in SIMMER. Presently only a microscopic treatment is considered, but preliminary macroscopic algorithms have been investigated

Coefficients of singularities and mixed methods for the mixed Dirichlet-Neumann problem for the Stokes operator on a polygon

International Nuclear Information System (INIS)

Chettab, M.; Lubuma, M.S.

1990-08-01

The behaviour of the weak solution of the Stokes problem on a polygon is considered with emphasis on the maximal regularity of the solution and on global formulae for the coefficients of singularities. This regularity leads to a slow convergent mixed finite element method of fractional order less than one while the use of the above formulae provides better approximations for the solution and for the coefficients. (author). 32 refs

Near polygons and Fischer spaces

NARCIS (Netherlands)

Brouwer, A.E.; Cohen, A.M.; Hall, J.I.; Wilbrink, H.A.

1994-01-01

In this paper we exploit the relations between near polygons with lines of size 3 and Fischer spaces to classify near hexagons with quads and with lines of size three. We also construct some infinite families of near polygons.

Electron-impact cross sections of Ne

International Nuclear Information System (INIS)

Tsurubuchi, S.; Arakawa, K.; Kinokuni, S.; Motohashi, K.

2000-01-01

Electron-impact absolute emission cross sections were measured for the 3p→3s transitions of Ne. Excitation functions of the 3s→2p first resonance lines were measured in the energy range from the threshold to 1000 eV by a polarization-free optical method and relative cross sections were normalized to the absolute values, (41.0±5.4)x10 -19 cm 2 for the 73.6 nm line and (7.1±1.0)x10 -19 cm 2 for the 74.4 nm line, which were determined at 500 eV. The integrated level-excitation cross sections of Suzuki et al for the 1s 2 and 1s 4 levels were combined with the corresponding 3p→3s cascade cross sections obtained in this paper to give absolute emission cross sections for the resonance lines. The level-excitation cross sections of the 1s 2 and 1s 4 states in Paschen notation were determined from the threshold to 1000 eV by subtracting 3p→3s cascade cross sections from the corresponding 3s→2p emission cross sections of the resonance lines. A large cascade contribution is found in the emission cross section of the resonance lines. It is 28.5% for the 73.6 nm line and 49.6% for the 74.4 nm line at 40 eV, and 17.0 and 61.8%, respectively, at 300 eV. (author)

Neutron cross sections: Book of curves

International Nuclear Information System (INIS)

McLane, V.; Dunford, C.L.; Rose, P.F.

1988-01-01

Neuton Cross Sections: Book of Curves represents the fourth edition of what was previously known as BNL-325, Neutron Cross Sections, Volume 2, CURVES. Data is presented only for (i.e., intergrated) reaction cross sections (and related fission parameters) as a function of incident-neutron energy for the energy range 0.01 eV to 200 MeV. For the first time, isometric state production cross sections have been included. 11 refs., 4 figs

Evaluated cross section libraries

International Nuclear Information System (INIS)

Maqurno, B.A.

1976-01-01

The dosimetry tape (ENDF/B-IV tape 412) was issued in a general CSEWG distribution, August 1974. The pointwise cross section data file was tested with specified reference spectra. A group averaged cross section data file (620 groups based on tape 412) was tested with the above spectra and the results are presented in this report

Verbal working memory is related to the acquisition of cross-linguistic phonological regularities

NARCIS (Netherlands)

Bosma, E.; Heeringa, W.; Hoekstra, E.; Versloot, A.; Blom, E.

Closely related languages share cross-linguistic phonological regularities, such as Frisian -âld [c:t] and Dutch -oud [hut], as in the cognate pairs kâld [kc:t] - koud [khut] 'cold' and wâld [wc:t] - woud [whut] 'forest'. Within Bybee's (1995, 2001, 2008, 2010) network model, these regularities are,

Compilation of electron collision excitation cross sections for neutral argon

International Nuclear Information System (INIS)

Blanco, F.

1993-01-01

The present work presents a compilation and critical analysis of the available data on electron collision excitation cross sections for neutral Argon levels. This study includes: 1.- A detailed description in intermediate coupling for all the levels belonging the 20 configurations 3p5 ns (n=4to 12), np(n=4to8) and nd(n=3to8)of neutral Argon. 2.- Calculation of the electron collision excitation cross sections in Born and Born-Oppenheimer-Ochkur approximations for all the levels in the 14 configurations 3p5 ns (n=4 to 7), np (n=4 to 7) and nd (n=3 to 8). 3.- comparison and discussion of the compiled data. These are the experimental and theoretical values available from the literature, and those from this work. 4.- Analysis of the regularities and systematic behaviors in order to determine which values can be considered more reliable. It is show that the concept of one electron cross section results quite useful for this purpose. In some cases it has been possible to obtain in this way approximate analytical expressions interpolating the experimental data. 5.- All the experimental and theoretical values studied are graphically presented and compared. 6.- The last part of the work includes a listing of several general purpose programs for Atomic Physics calculations developed for this work. (Author) 35 refs

Compilation of electron collision excitation cross sections for neutro argon

International Nuclear Information System (INIS)

Blanco Ramos, F.

1993-01-01

The present work presents a compilation and critical analysis of the available data on electron collision excitation cross sections for neutral Argon levels. This study includes: 1.- A detailed description in intermediate coupling for all the levels belonging the 20 configurations 3p''5 ns(n=4 to 12), np(n=4 to 8) and nd(n=3 to 8) of neutral Argon. 2.- Calculation of the electron collision excitation cross sections in Born and Born-Oppenheimer-Ochkur approximations for all the levels in the 14 configurations 3p''5 ns(n=4 to 7), np(n=4 to 7) and nd(n=3 to 8). 3.- Comparison and discussion of the compiled data. These are the experimental and theoretical values available from the literature, and those from this work. 4.- Analysis of the regularities and systematic behaviors in order to determine which values can be considered more reliable. It is show that the concept of one electron cross section results quite useful for this purpose. In some cases it has been possible to obtain in this way approximate analytical expressions interpolating the experimental data. 5.- All the experimental and theoretical values studied are graphically presented and compared. 6.- The last part of the work includes a listing of several general purpose programs for Atomic Physics calculations developed for this work. (Author)

Empirical regularities in the excitation cross-section behavior of the lead atom (transitions from energy levels of 6pnd configurations)

Science.gov (United States)

Smirnov, Yu M.

2018-03-01

Electron-impact excitation of lead atom levels belonging to 6pnd configurations has been studied in experiment. One hundred two excitation cross-sections have been measured at an incident electron energy of 50 eV. Eleven optical excitation functions (OEFs) have been recorded in the exciting electron energy range of E = 0-200 eV. The resulting findings were used to study the excitation cross-sections dependence on the principal quantum number of upper levels for thirteen PbI spectral series.

Subsatellite polygon for studying hydrophysical processes in the Black Sea shelf-slope zone

Science.gov (United States)

Zatsepin, A. G.; Ostrovskii, A. G.; Kremenetskiy, V. V.; Nizov, S. S.; Piotukh, V. B.; Soloviev, V. A.; Shvoev, D. A.; Tsibul'sky, A. L.; Kuklev, S. B.; Kukleva, O. N.; Moskalenko, L. V.; Podymov, O. I.; Baranov, V. I.; Kondrashov, A. A.; Korzh, A. O.; Kubryakov, A. A.; Soloviev, D. M.; Stanichny, S. V.

2014-01-01

The first data on the creation of the subsatellite polygon on the Black Sea shelf and continental slope in the Gelendzhik area (designed in order to permanently monitor the state of the aquatic environment and biota) and the plans for maintaining and developing this polygon are presented. The autonomous measuring systems of the polygon in the composition of bottom stations with acoustic Doppler current profilers (ADCP), Aqualog robotic profilers, and thermo-chains on moored buoy stations should make it possible to regularly obtain hydrophysical, hydrochemical, and bio-optical data with a high spatial-time resolution and transmit these data to the coastal center on a real-time basis. These field data should be used to study the characteristics and formation mechanisms of the marine environment and biota variability, as well as the water-exchange processes in the shelf-deep basin system, ocean-atmosphere coupling, and many other processes. These data are used to calibrate the satellite measurements and verify the water circulation numerical simulation. It is assumed to use these data in order to warn about the hazardous natural phenomena and control the marine environment state and its variation under the action of anthropogenic and natural factors, including climatic trends. It is planned to use the polygon subsatellite monitoring methods and equipment in other coastal areas, including other Black Sea sectors, in order to create a unified system for monitoring the Black Sea shelf-slope zone.

Statistical investigation of avalanches of three-dimensional small-world networks and their boundary and bulk cross-sections

Science.gov (United States)

Najafi, M. N.; Dashti-Naserabadi, H.

2018-03-01

In many situations we are interested in the propagation of energy in some portions of a three-dimensional system with dilute long-range links. In this paper, a sandpile model is defined on the three-dimensional small-world network with real dissipative boundaries and the energy propagation is studied in three dimensions as well as the two-dimensional cross-sections. Two types of cross-sections are defined in the system, one in the bulk and another in the system boundary. The motivation of this is to make clear how the statistics of the avalanches in the bulk cross-section tend to the statistics of the dissipative avalanches, defined in the boundaries as the concentration of long-range links (α ) increases. This trend is numerically shown to be a power law in a manner described in the paper. Two regimes of α are considered in this work. For sufficiently small α s the dominant behavior of the system is just like that of the regular BTW, whereas for the intermediate values the behavior is nontrivial with some exponents that are reported in the paper. It is shown that the spatial extent up to which the statistics is similar to the regular BTW model scales with α just like the dissipative BTW model with the dissipation factor (mass in the corresponding ghost model) m2˜α for the three-dimensional system as well as its two-dimensional cross-sections.

Polygonal-path approximations on the path spaces of quantum-mechanical systems: properties of the polygonal paths

International Nuclear Information System (INIS)

Exner, P.; Kolerov, G.I.

1981-01-01

Properties of the subset of polygonal paths in the Hilbert space H of paths referring to a d-dimensional quantum-mechanical system are examined. Using the reproduction kernel technique we prove that each element of H is approximated by polygonal paths uniformly with respect to the ''norm'' of time-interval partitions. This result will be applied in the second part of the present paper to prove consistency of the uniform polygonal-path extension of the Feynman maps [ru

A formational model for the polygonal terrains of Mars: Taking a crack at the genesis of the Martian polygons

Science.gov (United States)

Wenrich, M. L.; Christensen, P. R.

1993-01-01

The mechanism for the genesis of the polygonal terrains in Acidalia and Utopia Planitia has long been sought: however, no completely satisfying model was put forth that characterizes the evolution of these complexly patterned terrains. The polygons are roughly hexagonal but some are not entirely enclosed by fractures. These polygonal features range in widths from approximately 5 to 20 km. Several origins were proposed that describe the polygon borders as desiccation cracks, columnar jointing in a cooled lava, or frost-wedge features. These tension-induced cracking hypotheses were addressed by Pechmann, who convincingly disputes these mechanisms of formation based on scale magnitude difficulties and morphology. Pechmann suggests instead that the cracks delineating the 5-20-km-wide polygons on the northern plains of Mars are graben resulting from deep-seated, uniform, horizontal tension. The difficulty with this hypothesis is that no analogous polygonal forms are known to have originated by tectonism on Earth. McGill and Hills propose that the polygonal terrains on Mars resulted from either rapid desiccation of sediments or cooling of volcanics coupled with differential compaction of the material over a buried irregular topographic surface. They suggest that fracturing was enhanced over the areas of positive relief and was suppressed above the topographic lows. McGill and Hills suggest that the spacing of the topographic highs primarily controls the size of the Martian polygons and the physics of the shrinkage process is a secondary concern. Ray et. al. conducted a terrestrial study of patterned ground in periglacial areas of the U.S. to determine the process responsible for polygonal ground formation. They developed a model for polygon formation in which convection of seasonal melt water above a permafrost layer, driven by an unstable density stratification, differentially melts the permafrost interface, causing it to become undulatory.

Model for polygonal hydraulic jumps

DEFF Research Database (Denmark)

Martens, Erik Andreas; Watanabe, Shinya; Bohr, Tomas

2012-01-01

We propose a phenomenological model for the polygonal hydraulic jumps discovered by Ellegaard and co-workers [Nature (London) 392, 767 (1998); Nonlinearity 12, 1 (1999); Physica B 228, 1 (1996)], based on the known flow structure for the type-II hydraulic jumps with a "roller" (separation eddy...... nonhydrostatic pressure contributions from surface tension in light of recent observations by Bush and co-workers [J. Fluid Mech. 558, 33 (2006); Phys. Fluids 16, S4 (2004)]. The model can be analyzed by linearization around the circular state, resulting in a parameter relationship for nearly circular polygonal...... states. A truncated but fully nonlinear version of the model can be solved analytically. This simpler model gives rise to polygonal shapes that are very similar to those observed in experiments, even though surface tension is neglected, and the condition for the existence of a polygon with N corners...

Pizza Again? On the Division of Polygons into Sections with a Common Origin

Science.gov (United States)

Sinitsky, Ilya; Stupel, Moshe; Sinitsky, Marina

2018-01-01

The paper explores the division of a polygon into equal-area pieces using line segments originating at a common point. The mathematical background of the proposed method is very simple and belongs to secondary school geometry. Simple examples dividing a square into two, four or eight congruent pieces provide a starting point to discovering how to…

Measurement and calculation of excitation cross sections and level ionization by electron impact

International Nuclear Information System (INIS)

Blanco Rames, F.

1990-01-01

The experimental and theoretical study of the atomic structure in neutral noble gases is studied in this work. It mainly deals with the determination of total cross sections by electron impact and transition probabilities, including: Chapter 1: Theoretical introduction and the intermediate coupling description obtained for 420 levels of s, p and d configurations in neutral noble gases. Chapter 2: Experimental and theoretical values for electron collision cross sections are obtained for several levels of He, Ne, Ar and Kr. Our results as well as those available from existing bibliography are sumarized and compared. By means of an intermediate coupling treatment a number of regularities is found that provides us with some useful approximate semi empirical expressions. Chapter 3: Determination of lifetime and transition probabilities. Lifetime measurements are carried out by means of laser excitation and multichannel delayed coincidences technique. The experimental setup and electronics are also described. Chapter 4: Details the experimental setup developed for electron cross sections measurement by the optical method. The difficulties of this method and their treatment are also shown. (Author)

Nuclear Forensics and Radiochemistry: Cross Sections

Energy Technology Data Exchange (ETDEWEB)

Rundberg, Robert S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-11-08

The neutron activation of components in a nuclear device can provide useful signatures of weapon design or sophistication. This lecture will cover some of the basics of neutron reaction cross sections. Nuclear reactor cross sections will also be presented to illustrate the complexity of convolving neutron energy spectra with nuclear excitation functions to calculate useful effective reactor cross sections. Deficiencies in the nuclear database will be discussed along with tools available at Los Alamos to provide new neutron cross section data.

Polygons and Craters

Science.gov (United States)

2005-01-01

3 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows polygons enhanced by subliming seasonal frost in the martian south polar region. Polygons similar to these occur in frozen ground at high latitudes on Earth, suggesting that perhaps their presence on Mars is also a sign that there is or once was ice in the shallow subsurface. The circular features are degraded meteor impact craters. Location near: 72.2oS, 310.3oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

Differential Top Cross-section Measurements

CERN Document Server

Fenton, Michael James; The ATLAS collaboration

2017-01-01

The top quark is the heaviest known fundamental particle. The measurement of the differential top-quark pair production cross-section provides a stringent test of advanced perturbative QCD calculations. The ATLAS collaboration has performed detailed measurements of those differential cross sections at a centre-of-mass energy of 13 TeV. This talk focuses on differential cross-section measurements in the lepton+jets final state, including using boosted top quarks to probe our understanding of top quark production in the TeV regime.

Activation cross section data file, (1)

International Nuclear Information System (INIS)

Yamamuro, Nobuhiro; Iijima, Shungo.

1989-09-01

To evaluate the radioisotope productions due to the neutron irradiation in fission of fusion reactors, the data for the activation cross sections ought to be provided. It is planning to file more than 2000 activation cross sections at final. In the current year, the neutron cross sections for 14 elements from Ni to W have been calculated and evaluated in the energy range 10 -5 to 20 MeV. The calculations with a simplified-input nuclear cross section calculation system SINCROS were described, and another method of evaluation which is consistent with the JENDL-3 were also mentioned. The results of cross section calculation are in good agreement with experimental data and they were stored in the file 8, 9 and 10 of ENDF/B format. (author)

Self-avoiding polygons and walks in slits

International Nuclear Information System (INIS)

Alvarez, J; Whittington, S G; Rensburg, E J Janse van; Soteros, C E

2008-01-01

A polymer in a confined geometry may be modeled by a self-avoiding walk or a self-avoiding polygon confined between two parallel walls. In two dimensions, this model involves self-avoiding walks or self-avoiding polygons in the square lattice between two parallel confining lines. Interactions of the polymer with the confining walls are introduced by energy terms associated with edges in the walk or polygon which are at or near the confining lines. We use transfer-matrix methods to investigate the forces between the walk or polygon and the confining lines, as well as to investigate the effects of the confining slit's width and of the energy terms on the thermodynamic properties of the walks or polygons in several models. The phase diagram found for the self-avoiding walk models is qualitatively similar to the phase diagram of a directed walk model confined between two parallel lines, as was previously conjectured. However, the phase diagram of one of our polygon models is found to be significantly different and we present numerical data to support this. For that particular model we prove that, for any finite values of the energy terms, there are an infinite number of slit widths where a polygon will induce a steric repulsion between the confining lines

Utilization of cross-section covariance data in FBR core nuclear design and cross-section adjustment

International Nuclear Information System (INIS)

Ishikawa, Makoto

1994-01-01

In the core design of large fast breeder reactors (FBRs), it is essentially important to improve the prediction accuracy of nuclear characteristics from the viewpoint of both reducing cost and insuring reliability of the plant. The cross-section errors, that is, covariance data are one of the most dominant sources for the prediction uncertainty of the core parameters, therefore, quantitative evaluation of covariance data is indispensable for FBR core design. The first objective of the present paper is to introduce how the cross-section covariance data are utilized in the FBR core nuclear design works. The second is to delineate the cross-section adjustment study and its application to an FBR design, because this improved design method markedly enhances the needs and importance of the cross-section covariance data. (author)

Is the quasielastic pion cross section really bigger than the pion-nucleus reaction cross section

International Nuclear Information System (INIS)

Silbar, R.R.

1979-01-01

It is shown that soft pion charge exchanges may increase the inclusive (π + ,π 0 ') cross section, relative to the total quasielastic (π + ,π + ') cross section, by as much as a factor of two. 4 references

Dilation-optimal edge deletion in polygonal cycles

NARCIS (Netherlands)

Ahn, H.K.; Farshi, M.; Knauer, C.; Smid, M.H.M.; Wang, Y.; Tokuyama, T.

2007-01-01

Let C be a polygonal cycle on n vertices in the plane. A randomized algorithm is presented which computes in O(n log3 n) expected time, the edge of C whose removal results in a polygonal path of smallest possible dilation. It is also shown that the edge whose removal gives a polygonal path of

JENDL gas-production cross section file

International Nuclear Information System (INIS)

Nakagawa, Tsuneo; Narita, Tsutomu

1992-05-01

The JENDL gas-production cross section file was compiled by taking cross-section data from JENDL-3 and by using the ENDF-5 format. The data were given to 23 nuclei or elements in light nuclei and structural materials. Graphs of the cross sections and brief description on their evaluation methods are given in this report. (author)

Invariant polygons in systems with grazing-sliding.

Science.gov (United States)

Szalai, R; Osinga, H M

2008-06-01

The paper investigates generic three-dimensional nonsmooth systems with a periodic orbit near grazing-sliding. We assume that the periodic orbit is unstable with complex multipliers so that two dominant frequencies are present in the system. Because grazing-sliding induces a dimension loss and the instability drives every trajectory into sliding, the system has an attractor that consists of forward sliding orbits. We analyze this attractor in a suitably chosen Poincare section using a three-parameter generalized map that can be viewed as a normal form. We show that in this normal form the attractor must be contained in a finite number of lines that intersect in the vertices of a polygon. However the attractor is typically larger than the associated polygon. We classify the number of lines involved in forming the attractor as a function of the parameters. Furthermore, for fixed values of parameters we investigate the one-dimensional dynamics on the attractor.

Doppler broadening of cross sections

International Nuclear Information System (INIS)

Buckler, P.A.C.; Pull, I.C.

1962-12-01

Expressions for temperature dependent cross-sections in terms of resonance parameters are obtained, involving generalisations of the conventional Doppler functions, ψ and φ. Descriptions of Fortran sub-routines, which calculate broadened cross-sections in accordance with the derived formulae, are included. (author)

Generating random walks and polygons with stiffness in confinement

International Nuclear Information System (INIS)

Diao, Y; Ernst, C; Saarinen, S; Ziegler, U

2015-01-01

The purpose of this paper is to explore ways to generate random walks and polygons in confinement with a bias toward stiffness. Here the stiffness refers to the curvature angle between two consecutive edges along the random walk or polygon. The stiffer the walk (polygon), the smaller this angle on average. Thus random walks and polygons with an elevated stiffness have lower than expected curvatures. The authors introduced and studied several generation algorithms with a stiffness parameter s>0 that regulates the expected curvature angle at a given vertex in which the random walks and polygons are generated one edge at a time using conditional probability density functions. Our generating algorithms also allow the generation of unconfined random walks and polygons with any desired mean curvature angle. In the case of random walks and polygons confined in a sphere of fixed radius, we observe that, as expected, stiff random walks or polygons are more likely to be close to the confinement boundary. The methods developed here require that the random walks and random polygons be rooted at the center of the confinement sphere. (paper)

Cross-sectional anatomy for computed tomography

International Nuclear Information System (INIS)

Farkas, M.L.

1988-01-01

This self-study guide recognizes that evaluation and interpretation of CT-images demands a firm understanding of both cross-sectional anatomy and the principles of computed tomography. The objectives of this book are: to discuss the basic principles of CT, to stress the importance of cross-sectional anatomy to CT through study of selected cardinal transverse sections of head, neck, and trunk, to explain orientation and interpretation of CT-images with the aid of corresponding cross-sectional preparations

Density-dependent expressions for photoionization cross-sections

International Nuclear Information System (INIS)

Sun Weiguo; Ma Xiaoguang; Cheng Yansong

2004-01-01

Alternative expressions for photoionization cross-sections and dielectric influence functions are suggested to study the photoionization cross-sections of atoms in solid system. The basic picture is that the photoionization cross-section of atoms in a real system can be described as the coupling between quantum quantity (QQ) and classical quantity (CQ) parts. The QQ part represents the photoionization cross-sections of an isolated particle, while the CQ part may represent most of the important influence of the macroscopic effects (e.g., the interactions of all surrounding polarized particles, and the dielectric property, etc.) on the photoionization cross-sections. The applications to the barium system show that the number-density-dependent new photoionization formula not only obtains the same cross-sections as those from the first order approximation for ideal gas, but also can generate the cross-sections for solid barium by transforming those of ideal gas of the same species using the dielectric influence function

Density-dependent expressions for photoionization cross-sections

Energy Technology Data Exchange (ETDEWEB)

Sun Weiguo; Ma Xiaoguang; Cheng Yansong

2004-06-07

Alternative expressions for photoionization cross-sections and dielectric influence functions are suggested to study the photoionization cross-sections of atoms in solid system. The basic picture is that the photoionization cross-section of atoms in a real system can be described as the coupling between quantum quantity (QQ) and classical quantity (CQ) parts. The QQ part represents the photoionization cross-sections of an isolated particle, while the CQ part may represent most of the important influence of the macroscopic effects (e.g., the interactions of all surrounding polarized particles, and the dielectric property, etc.) on the photoionization cross-sections. The applications to the barium system show that the number-density-dependent new photoionization formula not only obtains the same cross-sections as those from the first order approximation for ideal gas, but also can generate the cross-sections for solid barium by transforming those of ideal gas of the same species using the dielectric influence function.

Verbal Working Memory Is Related to the Acquisition of Cross-Linguistic Phonological Regularities

NARCIS (Netherlands)

Bosma, E.; Heeringa, Wilbert; Hoekstra, E.; Versloot, A.P.; Blom, W.B.T.

2017-01-01

Closely related languages share cross-linguistic phonological regularities, such as Frisian -âld [ͻ:t] and Dutch -oud [ʱut], as in the cognate pairs kâld [kͻ:t] – koud [kʱut] ‘cold’ and wâld [wͻ:t] – woud [wʱut] ‘forest’. Within Bybee’s (1995, 2001, 2008, 2010) network model, these regularities are,

Automatically repairing invalid polygons with a constrained triangulation

NARCIS (Netherlands)

Ledoux, H.; Arroyo Ohori, K.; Meijers, M.

2012-01-01

Although the validation of single polygons has received considerable attention, the automatic repair of invalid polygons has not. Automated repair methods can be considered as interpreting ambiguous or ill-defined polygons and giving a coherent and clearly defined output. At this moment, automatic

Generating equilateral random polygons in confinement II

International Nuclear Information System (INIS)

Diao, Y; Ernst, C; Montemayor, A; Ziegler, U

2012-01-01

In this paper we continue an earlier study (Diao et al 2011 J. Phys. A: Math. Theor. 44 405202) on the generation algorithms of random equilateral polygons confined in a sphere. Here, the equilateral random polygons are rooted at the center of the confining sphere and the confining sphere behaves like an absorbing boundary. One way to generate such a random polygon is the accept/reject method in which an unconditioned equilateral random polygon rooted at origin is generated. The polygon is accepted if it is within the confining sphere, otherwise it is rejected and the process is repeated. The algorithm proposed in this paper offers an alternative to the accept/reject method, yielding a faster generation process when the confining sphere is small. In order to use this algorithm effectively, a large, reusable data set needs to be pre-computed only once. We derive the theoretical distribution of the given random polygon model and demonstrate, with strong numerical evidence, that our implementation of the algorithm follows this distribution. A run time analysis and a numerical error estimate are given at the end of the paper. (paper)

Does a point lie inside a polygon

International Nuclear Information System (INIS)

Milgram, M.S.

1988-01-01

A superficially simple problem in computational geometry is that of determining whether a query point P lies in the interior of a polygon if it lies in the polygon's plane. Answering this question is often required when tracking particles in a Monte Carlo program; it is asked frequently and an efficient algorithm is crucial. Littlefield has recently rediscovered Shimrat's algorithm, while in separate works, Wooff, Preparata and Shamos and Mehlhorn, as well as Yamaguchi, give other algorithms. A practical algorithm answering this question when the polygon's plane is skewed in space is not immediately evident from most of these methods. Additionally, all but one fails when two sides extend to infinity (open polygons). In this paper the author review the above methods and present a new, efficient algorithm, valid for all convex polygons, open or closed, and topologically connected in n-dimensional space (n ≥ 2)

Total neutron cross section of lead

International Nuclear Information System (INIS)

Kanda, K.; Aizawa, O.

1976-01-01

The total thermal-neutron cross section of natural lead under various physical conditions was measured by the transmission method. It became clear that the total cross section at room temperature previously reported is lower than the present data. The total cross section at 400, 500, and 600 0 C, above the melting point of lead, 327 0 C, was also measured, and the changes in the cross section as a function of temperature were examined, especially near and below the melting point. The data obtained for the randomly oriented polycrystalline state at room temperature were in reasonable agreement with the theoretical values calculated by the THRUSH and UNCLE-TOM codes

BLM National Surface Management Agency: Area Polygons, Withdrawal Area Polygons, and Special Public Purpose Withdrawal Area Polygons

Data.gov (United States)

Federal Geographic Data Committee — The SMA implementation is comprised of one feature dataset, with several polygon feature classes, rather than a single feature class. SurfaceManagementAgency: The...

Fast voxel and polygon ray-tracing algorithms in intensity modulated radiation therapy treatment planning

International Nuclear Information System (INIS)

Fox, Christopher; Romeijn, H. Edwin; Dempsey, James F.

2006-01-01

We present work on combining three algorithms to improve ray-tracing efficiency in radiation therapy dose computation. The three algorithms include: An improved point-in-polygon algorithm, incremental voxel ray tracing algorithm, and stereographic projection of beamlets for voxel truncation. The point-in-polygon and incremental voxel ray-tracing algorithms have been used in computer graphics and nuclear medicine applications while the stereographic projection algorithm was developed by our group. These algorithms demonstrate significant improvements over the current standard algorithms in peer reviewed literature, i.e., the polygon and voxel ray-tracing algorithms of Siddon for voxel classification (point-in-polygon testing) and dose computation, respectively, and radius testing for voxel truncation. The presented polygon ray-tracing technique was tested on 10 intensity modulated radiation therapy (IMRT) treatment planning cases that required the classification of between 0.58 and 2.0 million voxels on a 2.5 mm isotropic dose grid into 1-4 targets and 5-14 structures represented as extruded polygons (a.k.a. Siddon prisms). Incremental voxel ray tracing and voxel truncation employing virtual stereographic projection was tested on the same IMRT treatment planning cases where voxel dose was required for 230-2400 beamlets using a finite-size pencil-beam algorithm. Between a 100 and 360 fold cpu time improvement over Siddon's method was observed for the polygon ray-tracing algorithm to perform classification of voxels for target and structure membership. Between a 2.6 and 3.1 fold reduction in cpu time over current algorithms was found for the implementation of incremental ray tracing. Additionally, voxel truncation via stereographic projection was observed to be 11-25 times faster than the radial-testing beamlet extent approach and was further improved 1.7-2.0 fold through point-classification using the method of translation over the cross product technique

Top quark production cross-section measurements

CERN Document Server

Chen, Ye; The ATLAS collaboration

2017-01-01

Measurements of the inclusive and differential cross-sections for top-quark pair and single top production cross sections in proton-proton collisions with the ATLAS detector at the Large Hadron Collider are presented at center-of-mass energies of 8 TeV and 13 TeV. The inclusive measurements reach high precision and are compared to the best available theoretical calculations. These measurements, including results using boosted tops, probe our understanding of top-pair production in the TeV regime. The results are compared to Monte Carlo generators implementing LO and NLO matrix elements matched with parton showers and NLO QCD calculations. For the t-channel single top measurement, the single top-quark and anti-top-quark total production cross-sections, their ratio, as well as differential cross sections are also presented. A measurement of the production cross-section of a single top quark in association with a W boson, the second largest single-top production mode, is also presented. Finally, measurements of ...

Differences between LASL- and ANL-processed cross sections

International Nuclear Information System (INIS)

Kidman, R.B.; MacFarlane, R.E.; Becker, M.

1978-03-01

As part of the Los Alamos Scientific Laboratory (LASL) cross-section processing development, LASL cross sections and results from MINX/1DX system are compared to the Argonne National Laboratory cross sections and results from the ETOE-2/MC 2 -2 system for a simple reactor problem. Exact perturbation theory is used to establish the eigenvalue effect of every isotope group cross-section difference. Cross sections, cross-section differences, and their eigenvalue effects are clearly and conveniently displayed and compared on a group-by-group basis

Linking of uniform random polygons in confined spaces

International Nuclear Information System (INIS)

Arsuaga, J; Blackstone, T; Diao, Y; Karadayi, E; Saito, M

2007-01-01

In this paper, we study the topological entanglement of uniform random polygons in a confined space. We derive the formula for the mean squared linking number of such polygons. For a fixed simple closed curve in the confined space, we rigorously show that the linking probability between this curve and a uniform random polygon of n vertices is at least 1-O(1/√n). Our numerical study also indicates that the linking probability between two uniform random polygons (in a confined space), of m and n vertices respectively, is bounded below by 1-O(1/√(mn)). In particular, the linking probability between two uniform random polygons, both of n vertices, is bounded below by 1-O(1/n)

From Newton's bucket to rotating polygons

DEFF Research Database (Denmark)

Bach, B.; Linnartz, E. C.; Vested, Malene Louise Hovgaard

2014-01-01

We present an experimental study of 'polygons' forming on the free surface of a swirling water flow in a partially filled cylindrical container. In our set-up, we rotate the bottom plate and the cylinder wall with separate motors. We thereby vary rotation rate and shear strength independently...... and move from a rigidly rotating 'Newton's bucket' flow to one where bottom and cylinder wall are rotating oppositely and the surface is strongly turbulent but flat on average. Between those two extremes, we find polygonal states for which the rotational symmetry is spontaneously broken. We investigate...... the phase diagram spanned by the two rotational frequencies at a given water filling height and find polygons in a regime, where the two frequencies are sufficiently different and, predominantly, when they have opposite signs. In addition to the extension of the family of polygons found with the stationary...

(n,{alpha}) cross section measurement of gaseous sample using gridded ionization chamber. Cross section determination

Energy Technology Data Exchange (ETDEWEB)

Sanami, Toshiya; Baba, Mamoru; Saito, Keiichiro; Ibara, Yasutaka; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

1997-03-01

We are developing a method of (n,{alpha}) cross section measurement using gaseous samples in a gridded ionization chamber (GIC). This method enables cross section measurements in large solid angle without the distortion by the energy loss in a sample, but requires a method to estimate the detection efficiency. We solve this problem by using GIC signals and a tight neutron collimation. The validity of this method was confirmed through the {sup 12}C(n,{alpha}{sub 0}){sup 9}Be measurement. We applied this method to the {sup 16}O(n,{alpha}){sup 13}C cross section around 14.1 MeV. (author)

Null-polygonal minimal surfaces in AdS4 from perturbed W minimal models

International Nuclear Information System (INIS)

Hatsuda, Yasuyuki; Ito, Katsushi; Satoh, Yuji

2012-11-01

We study the null-polygonal minimal surfaces in AdS 4 , which correspond to the gluon scattering amplitudes/Wilson loops in N=4 super Yang-Mills theory at strong coupling. The area of the minimal surfaces with n cusps is characterized by the thermodynamic Bethe ansatz (TBA) integral equations or the Y-system of the homogeneous sine-Gordon model, which is regarded as the SU(n-4) 4 /U(1) n-5 generalized parafermion theory perturbed by the weight-zero adjoint operators. Based on the relation to the TBA systems of the perturbed W minimal models, we solve the TBA equations by using the conformal perturbation theory, and obtain the analytic expansion of the remainder function around the UV/regular-polygonal limit for n = 6 and 7. We compare the rescaled remainder function for n=6 with the two-loop one, to observe that they are close to each other similarly to the AdS 3 case.

Polygons on a rotating fluid surface

DEFF Research Database (Denmark)

Jansson, Thomas R.N.; Haspang, Martin P.; Jensen, Kåre H.

2006-01-01

We report a novel and spectacular instability of a fluid surface in a rotating system. In a flow driven by rotating the bottom plate of a partially filled, stationary cylindrical container, the shape of the free surface can spontaneously break the axial symmetry and assume the form of a polygon...... rotating rigidly with a speed different from that of the plate. With water, we have observed polygons with up to 6 corners. It has been known for many years that such flows are prone to symmetry breaking, but apparently the polygonal surface shapes have never been observed. The creation of rotating...

Generating equilateral random polygons in confinement

International Nuclear Information System (INIS)

Diao, Y; Ernst, C; Montemayor, A; Ziegler, U

2011-01-01

One challenging problem in biology is to understand the mechanism of DNA packing in a confined volume such as a cell. It is known that confined circular DNA is often knotted and hence the topology of the extracted (and relaxed) circular DNA can be used as a probe of the DNA packing mechanism. However, in order to properly estimate the topological properties of the confined circular DNA structures using mathematical models, it is necessary to generate large ensembles of simulated closed chains (i.e. polygons) of equal edge lengths that are confined in a volume such as a sphere of certain fixed radius. Finding efficient algorithms that properly sample the space of such confined equilateral random polygons is a difficult problem. In this paper, we propose a method that generates confined equilateral random polygons based on their probability distribution. This method requires the creation of a large database initially. However, once the database has been created, a confined equilateral random polygon of length n can be generated in linear time in terms of n. The errors introduced by the method can be controlled and reduced by the refinement of the database. Furthermore, our numerical simulations indicate that these errors are unbiased and tend to cancel each other in a long polygon. (paper)

Photoionization cross section of atomic and molecular oxygen

International Nuclear Information System (INIS)

Pareek, P.N.

1983-01-01

Photoionization cross sections of atomic oxygen and dissociative photoionization cross sections of molecular oxygen were measured from their respective thresholds to 120 angstrom by use of a photoionization mass spectrometer in conjunction with a spark light source. The photoionization cross sections O 2 + parent ion and O + fragment ion from neutral O 2 were obtained by a technique that eliminated the serious problem of identifying the true abundances of O + ions. These ions are generally formed with considerable kinetic energy and, because most mass spectrometers discriminate against energetic ions, true O + abundances are difficult to obtain. In the present work the relative cross sections for producing O + ions are obtained and normalized against the total cross sections in a spectral region where dissociative ionization is not possible. The fragmentation cross sections for O + were then obtained by subtraction of O 2 + cross sections from the known total photoionization cross sections. The results are compared with the previously published measurements. The absolute photoionization cross section of atomic oxygen sigma 8 /sub +/ was measured at 304 A. The actual number density of oxygen atoms within the ionization region was obtained by measuring the fraction of 0 2 molecules dissociated. This sigma/sub +/ at 304 angstrom was used to convert the relative photoinization cross sections, measured as a function of wavelength using a calibrated photodiode, to absolute cross sections. The results are compared with previous measurements and calculated cross sections. angstrom Rydberg series converging to the OII 4 P state was observed

Measurements of neutron capture cross sections

International Nuclear Information System (INIS)

Nakajima, Yutaka

1984-01-01

A review of measurement techniques for the neutron capture cross sections is presented. Sell transmission method, activation method, and prompt gamma-ray detection method are described using examples of capture cross section measurements. The capture cross section of 238 U measured by three different prompt gamma-ray detection methods (large liquid scintillator, Moxon-Rae detector, and pulse height weighting method) are compared and their discrepancies are resolved. A method how to derive the covariance is described. (author)

XCOM: Photon Cross Sections Database

Science.gov (United States)

SRD 8 XCOM: Photon Cross Sections Database (Web, free access)   A web database is provided which can be used to calculate photon cross sections for scattering, photoelectric absorption and pair production, as well as total attenuation coefficients, for any element, compound or mixture (Z <= 100) at energies from 1 keV to 100 GeV.

Linking of uniform random polygons in confined spaces

Science.gov (United States)

Arsuaga, J.; Blackstone, T.; Diao, Y.; Karadayi, E.; Saito, M.

2007-03-01

In this paper, we study the topological entanglement of uniform random polygons in a confined space. We derive the formula for the mean squared linking number of such polygons. For a fixed simple closed curve in the confined space, we rigorously show that the linking probability between this curve and a uniform random polygon of n vertices is at least 1-O\\big(\\frac{1}{\\sqrt{n}}\\big) . Our numerical study also indicates that the linking probability between two uniform random polygons (in a confined space), of m and n vertices respectively, is bounded below by 1-O\\big(\\frac{1}{\\sqrt{mn}}\\big) . In particular, the linking probability between two uniform random polygons, both of n vertices, is bounded below by 1-O\\big(\\frac{1}{n}\\big) .

Graphs of the cross sections in the recommended Monte Carlo cross-section library at the Los Alamos Scientific Laboratory

International Nuclear Information System (INIS)

Soran, P.D.; Seamon, R.E.

1980-05-01

Graphs of all neutron cross sections and photon production cross sections on the Recommended Monte Carlo Cross Section (RMCCS) library have been plotted along with local neutron heating numbers. Values for anti ν, the average number of neutrons per fission, are also given

Scattering cross section for various potential systems

Directory of Open Access Journals (Sweden)

Myagmarjav Odsuren

2017-08-01

Full Text Available We discuss the problems of scattering in this framework, and show that the applied method is very useful in the investigation of the effect of the resonance in the observed scattering cross sections. In this study, not only the scattering cross sections but also the decomposition of the scattering cross sections was computed for the α–α system. To obtain the decomposition of scattering cross sections into resonance and residual continuum terms, the complex scaled orthogonality condition model and the extended completeness relation are used. Applying the present method to the α–α and α–n systems, we obtained good reproduction of the observed phase shifts and cross sections. The decomposition into resonance and continuum terms makes clear that resonance contributions are dominant but continuum terms and their interference are not negligible. To understand the behavior of observed phase shifts and the shape of the cross sections, both resonance and continuum terms are calculated.

Scattering cross section for various potential systems

Energy Technology Data Exchange (ETDEWEB)

Odsuren, Myagmarjav; Khuukhenkhuu, Gonchigdorj; Davaa, Suren [Nuclear Research Center, School of Engineering and Applied Sciences, National University of Mongolia, Ulaanbaatar (Mongolia); Kato, Kiyoshi [Nuclear Reaction Data Centre, Faculty of Science, Hokkaido University, Sapporo (Japan)

2017-08-15

We discuss the problems of scattering in this framework, and show that the applied method is very useful in the investigation of the effect of the resonance in the observed scattering cross sections. In this study, not only the scattering cross sections but also the decomposition of the scattering cross sections was computed for the α–α system. To obtain the decomposition of scattering cross sections into resonance and residual continuum terms, the complex scaled orthogonality condition model and the extended completeness relation are used. Applying the present method to the α–α and α–n systems, we obtained good reproduction of the observed phase shifts and cross sections. The decomposition into resonance and continuum terms makes clear that resonance contributions are dominant but continuum terms and their interference are not negligible. To understand the behavior of observed phase shifts and the shape of the cross sections, both resonance and continuum terms are calculated.

NNLO jet cross sections by subtraction

International Nuclear Information System (INIS)

Somogyi, G.; Bolzoni, P.; Trocsanyi, Z.

2010-06-01

We report on the computation of a class of integrals that appear when integrating the so-called iterated singly-unresolved approximate cross section of an earlier NNLO subtraction scheme over the factorised phase space of unresolved partons. The integrated approximate cross section itself can be written as the product of an insertion operator (in colour space) times the Born cross section. We give selected results for the insertion operator for processes with two and three hard partons in the final state. (orig.)

NNLO jet cross sections by subtraction

Energy Technology Data Exchange (ETDEWEB)

Somogyi, G.; Bolzoni, P. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Trocsanyi, Z. [CERN, Geneva (Switzerland)

2010-06-15

We report on the computation of a class of integrals that appear when integrating the so-called iterated singly-unresolved approximate cross section of an earlier NNLO subtraction scheme over the factorised phase space of unresolved partons. The integrated approximate cross section itself can be written as the product of an insertion operator (in colour space) times the Born cross section. We give selected results for the insertion operator for processes with two and three hard partons in the final state. (orig.)

NNLO jet cross sections by subtraction

CERN Document Server

Somogyi, Gabor; Trocsanyi, Zoltan

2010-01-01

We report on the computation of a class of integrals that appear when integrating the so-called iterated singly-unresolved approximate cross section of the NNLO subtraction scheme of [1-4], over the factorised phase space of unresolved partons. The integrated approximate cross section itself can be written as the product of an insertion operator (in colour space) times the Born cross section. We give selected results for the insertion operator for processes with two and three hard partons in the final state.

Differential cross sections and cross-section ratios for the electron-impact excitation of the neon 2p53s configuration

International Nuclear Information System (INIS)

Khakoo, M. A.; Wrkich, J.; Larsen, M.; Kleiban, G.; Kanik, I.; Trajmar, S.; Brunger, M.J.; Teubner, P.J.O.; Crowe, A.; Fontes, C.J.; Clark, R.E.H.; Zeman, V.; Bartschat, K.; Madison, D.H.; Srivastava, R.; Stauffer, A.D.

2002-01-01

Electron-impact differential cross-section measurements for the excitation of the 2p 5 3s configuration of Ne are reported. The Ne cross sections are obtained using experimental differential cross sections for the electron-impact excitation of the n=2 levels of atomic hydrogen [Khakoo et al., Phys. Rev. A 61, 012701-1 (1999)], and existing experimental helium differential cross-section measurements, as calibration standards. These calibration measurements were made using the method of gas mixtures (Ne and H followed by Ne and He), in which the gas beam profiles of the mixed gases are found to be the same within our experimental errors. We also present results from calculations of these differential cross sections using the R-matrix and unitarized first-order many-body theory, the distorted-wave Born approximation, and relativistic distorted-wave methods. Comparison with available experimental differential cross sections and differential cross-section ratios is also presented

Capture cross sections on unstable nuclei

Science.gov (United States)

Tonchev, A. P.; Escher, J. E.; Scielzo, N.; Bedrossian, P.; Ilieva, R. S.; Humby, P.; Cooper, N.; Goddard, P. M.; Werner, V.; Tornow, W.; Rusev, G.; Kelley, J. H.; Pietralla, N.; Scheck, M.; Savran, D.; Löher, B.; Yates, S. W.; Crider, B. P.; Peters, E. E.; Tsoneva, N.; Goriely, S.

2017-09-01

Accurate neutron-capture cross sections on unstable nuclei near the line of beta stability are crucial for understanding the s-process nucleosynthesis. However, neutron-capture cross sections for short-lived radionuclides are difficult to measure due to the fact that the measurements require both highly radioactive samples and intense neutron sources. Essential ingredients for describing the γ decays following neutron capture are the γ-ray strength function and level densities. We will compare different indirect approaches for obtaining the most relevant observables that can constrain Hauser-Feshbach statistical-model calculations of capture cross sections. Specifically, we will consider photon scattering using monoenergetic and 100% linearly polarized photon beams. Challenges that exist on the path to obtaining neutron-capture cross sections for reactions on isotopes near and far from stability will be discussed.

Status of neutron dosimetry cross sections

International Nuclear Information System (INIS)

Griffin, P.J.; Kelly, J.G.

1992-01-01

Several new cross section libraries, such as ENDF/B-VI(release 2), IRDF-90,JEF-2.2, and JENDL-3 Dosimetry, have recently been made available to the dosimetry community. the Sandia National Laboratories (SNL) Radiation Metrology Laboratory (RML) has worked with these libraries since pre-release versions were available. this paper summarizes the results of the intercomparison and testing of dosimetry cross sections. As a result of this analysis, a compendium of the best dosimetry cross sections was assembled from the available libraries for use within the SNL RML. this library, referred to as the SNLRML Library, contains 66 general dosimetry sensors and 3 special dosimeters unique to the RML sensor inventory. The SNLRML cross sections have been put into a format compatible with commonly used spectrum determination codes

Capture cross sections on unstable nuclei

Directory of Open Access Journals (Sweden)

Tonchev A.P.

2017-01-01

Full Text Available Accurate neutron-capture cross sections on unstable nuclei near the line of beta stability are crucial for understanding the s-process nucleosynthesis. However, neutron-capture cross sections for short-lived radionuclides are difficult to measure due to the fact that the measurements require both highly radioactive samples and intense neutron sources. Essential ingredients for describing the γ decays following neutron capture are the γ-ray strength function and level densities. We will compare different indirect approaches for obtaining the most relevant observables that can constrain Hauser-Feshbach statistical-model calculations of capture cross sections. Specifically, we will consider photon scattering using monoenergetic and 100% linearly polarized photon beams. Challenges that exist on the path to obtaining neutron-capture cross sections for reactions on isotopes near and far from stability will be discussed.

Graphs of the cross sections in the Alternate Monte Carlo Cross Section library at the Los Alamos Scientific Laboratory

International Nuclear Information System (INIS)

Seamon, R.E.; Soran, P.D.

1980-06-01

Graphs of all neutron cross sections and photon production cross sections on the Alternate Monte Carlo Cross Section (AMCCS) library have been plotted along with local neutron heating numbers. The values of ν-bar, the average number of neutrons per fission, are also plotted for appropriate isotopes

Assessment of the profile of psychiatric manifestations in cannabis users: A cross sectional study

OpenAIRE

Indrajeet Sharma; Tulika Jha; Purshottam K. Kaundal

2016-01-01

Background: Cannabis is the world's most commonly used illicit drug, with approximately 200 to 300 million regular users. It occupies fourth place in worldwide popularity among psychoactive drugs, after caffeine, nicotine and alcohol. Nowadays, cannabis is widely used by young people and, the prevalence of lifetime use of cannabis by young adults has increased in many developed countries over the past several decades. Methods: It was a one year cross-sectional observational study. The stu...

Neutron-capture Cross Sections from Indirect Measurements

Energy Technology Data Exchange (ETDEWEB)

Escher, J E; Burke, J T; Dietrich, F S; Ressler, J J; Scielzo, N D; Thompson, I J

2011-10-18

Cross sections for compound-nuclear reactions play an important role in models of astrophysical environments and simulations of the nuclear fuel cycle. Providing reliable cross section data remains a formidable task, and direct measurements have to be complemented by theoretical predictions and indirect methods. The surrogate nuclear reactions method provides an indirect approach for determining cross sections for reactions on unstable isotopes, which are difficult or impossible to measure otherwise. Current implementations of the method provide useful cross sections for (n,f) reactions, but need to be improved upon for applications to capture reactions.

Probing convex polygons with X-rays

International Nuclear Information System (INIS)

Edelsbrunner, H.; Skiena, S.S.

1988-01-01

An X-ray probe through a polygon measures the length of intersection between a line and the polygon. This paper considers the properties of various classes of X-ray probes, and shows how they interact to give finite strategies for completely describing convex n-gons. It is shown that (3n/2)+6 probes are sufficient to verify a specified n-gon, while for determining convex polygons (3n-1)/2 X-ray probes are necessary and 5n+O(1) sufficient, with 3n+O(1) sufficient given that a lower bound on the size of the smallest edge of P is known

Atlas of photoneutron cross sections obtained with monoenergetic photons

International Nuclear Information System (INIS)

Dietrich, S.S.; Berman, B.L.

1988-01-01

Photoneutron cross-section and integrated cross-section data obtained with monoenergetic photons are presented in a uniform format. All of the measured partial photoneutron cross sections, the total photoneutron cross section, and the photoneutron yield cross section are plotted as functions of the incident photon energy, as are the integrated photoneutron cross sections and their first and second moments. The values of the integrated cross sections and the moments of the integrated total cross section up to the highest photon energy for which they were measured are tabulated, as are the parameters of Lorentz curves fitted to the total photoneutron cross-section data for medium and heavy nuclei (A>50). This compilation is current as of June 1987. copyright 1988 Academic Press, Inc

Cross-Sectional Analysis of Longitudinal Mediation Processes.

Science.gov (United States)

O'Laughlin, Kristine D; Martin, Monica J; Ferrer, Emilio

2018-01-01

Statistical mediation analysis can help to identify and explain the mechanisms behind psychological processes. Examining a set of variables for mediation effects is a ubiquitous process in the social sciences literature; however, despite evidence suggesting that cross-sectional data can misrepresent the mediation of longitudinal processes, cross-sectional analyses continue to be used in this manner. Alternative longitudinal mediation models, including those rooted in a structural equation modeling framework (cross-lagged panel, latent growth curve, and latent difference score models) are currently available and may provide a better representation of mediation processes for longitudinal data. The purpose of this paper is twofold: first, we provide a comparison of cross-sectional and longitudinal mediation models; second, we advocate using models to evaluate mediation effects that capture the temporal sequence of the process under study. Two separate empirical examples are presented to illustrate differences in the conclusions drawn from cross-sectional and longitudinal mediation analyses. Findings from these examples yielded substantial differences in interpretations between the cross-sectional and longitudinal mediation models considered here. Based on these observations, researchers should use caution when attempting to use cross-sectional data in place of longitudinal data for mediation analyses.

Comic image understanding based on polygon detection

Science.gov (United States)

Li, Luyuan; Wang, Yongtao; Tang, Zhi; Liu, Dong

2013-01-01

Comic image understanding aims to automatically decompose scanned comic page images into storyboards and then identify the reading order of them, which is the key technique to produce digital comic documents that are suitable for reading on mobile devices. In this paper, we propose a novel comic image understanding method based on polygon detection. First, we segment a comic page images into storyboards by finding the polygonal enclosing box of each storyboard. Then, each storyboard can be represented by a polygon, and the reading order of them is determined by analyzing the relative geometric relationship between each pair of polygons. The proposed method is tested on 2000 comic images from ten printed comic series, and the experimental results demonstrate that it works well on different types of comic images.

Minimal knotted polygons in cubic lattices

International Nuclear Information System (INIS)

Van Rensburg, E J Janse; Rechnitzer, A

2011-01-01

In this paper we examine numerically the properties of minimal length knotted lattice polygons in the simple cubic, face-centered cubic, and body-centered cubic lattices by sieving minimal length polygons from a data stream of a Monte Carlo algorithm, implemented as described in Aragão de Carvalho and Caracciolo (1983 Phys. Rev. B 27 1635), Aragão de Carvalho et al (1983 Nucl. Phys. B 215 209) and Berg and Foester (1981 Phys. Lett. B 106 323). The entropy, mean writhe, and mean curvature of minimal length polygons are computed (in some cases exactly). While the minimal length and mean curvature are found to be lattice dependent, the mean writhe is found to be only weakly dependent on the lattice type. Comparison of our results to numerical results for the writhe obtained elsewhere (see Janse van Rensburg et al 1999 Contributed to Ideal Knots (Series on Knots and Everything vol 19) ed Stasiak, Katritch and Kauffman (Singapore: World Scientific), Portillo et al 2011 J. Phys. A: Math. Theor. 44 275004) shows that the mean writhe is also insensitive to the length of a knotted polygon. Thus, while these results for the mean writhe and mean absolute writhe at minimal length are not universal, our results demonstrate that these values are quite close the those of long polygons regardless of the underlying lattice and length

Parametric equations for calculation of macroscopic cross sections

International Nuclear Information System (INIS)

Botelho, Mario Hugo; Carvalho, Fernando

2015-01-01

Neutronic calculations of the core of a nuclear reactor is one thing necessary and important for the design and management of a nuclear reactor in order to prevent accidents and control the reactor efficiently as possible. To perform these calculations a library of nuclear data, including cross sections is required. Currently, to obtain a cross section computer codes are used, which require a large amount of processing time and computer memory. This paper proposes the calculation of macroscopic cross section through the development of parametric equations. The paper illustrates the proposal for the case of macroscopic cross sections of absorption (Σa), which was chosen due to its greater complexity among other cross sections. Parametric equations created enable, quick and dynamic way, the determination of absorption cross sections, enabling the use of them in calculations of reactors. The results show efficient when compared with the absorption cross sections obtained by the ALPHA 8.8.1 code. The differences between the cross sections are less than 2% for group 2 and less than 0.60% for group 1. (author)

Gender and age inequalities in regular sports participation: a cross-national study of 25 European countries.

Science.gov (United States)

Van Tuyckom, Charlotte; Scheerder, Jeroen; Bracke, Piet

2010-08-01

This article provides a unique opportunity to compare gender inequalities in sports participation across Europe, and the extent to which this varies by age using large, cross-sections of the population. The Eurobarometer Survey 62.0 (carried out in 2004 at the request of the European Commission and covering the adult population of 25 European member states, N = 23,909) was used to analyse differences in regular sports participation by gender and by age in the different countries. For the majority of countries, the occurrence of regular sporting activity was less than 40%. Additionally, binary logistic regression analyses identified significant gender differences in sports participation in 12 countries. In Belgium, France, Greece, Latvia, Lithuania, Slovakia, Spain, and the UK, men were more likely to report being regularly active in sports than women, whereas in Denmark, Finland, Sweden, and the Netherlands the opposite was true. Moreover, the extent to which these gender inequalities differ by age varies considerably across countries. The results imply that: (i) in some European countries more efforts must be undertaken to promote the original goals of the Sport for All Charter, and (ii) to achieve more female participation in sports will require different policy responses in the diverse European member states.

Computing nonsimple polygons of minimum perimeter

NARCIS (Netherlands)

Fekete, S.P.; Haas, A.; Hemmer, M.; Hoffmann, M.; Kostitsyna, I.; Krupke, D.; Maurer, F.; Mitchell, J.S.B.; Schmidt, A.; Schmidt, C.; Troegel, J.

2018-01-01

We consider the Minimum Perimeter Polygon Problem (MP3): for a given set V of points in the plane, find a polygon P with holes that has vertex set V , such that the total boundary length is smallest possible. The MP3 can be considered a natural geometric generalization of the Traveling Salesman

Low Energy Neutrino Cross Sections

International Nuclear Information System (INIS)

Zeller, G.P.

2004-01-01

Present atmospheric and accelerator based neutrino oscillation experiments operate at low neutrino energies (Ev ∼ 1 GeV) to access the relevant regions of oscillation parameter space. As such, they require precise knowledge of the cross sections for neutrino-nucleon interactions in the sub-to-few GeV range. At these energies, neutrinos predominantly interact via quasi-elastic (QE) or single pion production processes, which historically have not been as well studied as the deep inelastic scattering reactions that dominate at higher energies.Data on low energy neutrino cross sections come mainly from bubble chamber, spark chamber, and emulsion experiments that collected their data decades ago. Despite relatively poor statistics and large neutrino flux uncertainties, these measurements provide an important and necessary constraint on Monte Carlo models in present use. The following sections discuss the current status of QE, resonant single pion, coherent pion, and single kaon production cross section measurements at low energy

Water polygons in high-resolution protein crystal structures.

Science.gov (United States)

Lee, Jonas; Kim, Sung-Hou

2009-07-01

We have analyzed the interstitial water (ISW) structures in 1500 protein crystal structures deposited in the Protein Data Bank that have greater than 1.5 A resolution with less than 90% sequence similarity with each other. We observed varieties of polygonal water structures composed of three to eight water molecules. These polygons may represent the time- and space-averaged structures of "stable" water oligomers present in liquid water, and their presence as well as relative population may be relevant in understanding physical properties of liquid water at a given temperature. On an average, 13% of ISWs are localized enough to be visible by X-ray diffraction. Of those, averages of 78% are water molecules in the first water layer on the protein surface. Of the localized ISWs beyond the first layer, almost half of them form water polygons such as trigons, tetragons, as well as expected pentagons, hexagons, higher polygons, partial dodecahedrons, and disordered networks. Most of the octagons and nanogons are formed by fusion of smaller polygons. The trigons are most commonly observed. We suggest that our observation provides an experimental basis for including these water polygon structures in correlating and predicting various water properties in liquid state.

Group cross-section processing method and common nuclear group cross-section library based on JENDL-3 nuclear data file

International Nuclear Information System (INIS)

Hasegawa, Akira

1991-01-01

A common group cross-section library has been developed in JAERI. This system is called 'JSSTDL-295n-104γ (neutron:295 gamma:104) group constants library system', which is composed of a common 295n-104γ group cross-section library based on JENDL-3 nuclear data file and its utility codes. This system is applicable to fast and fusion reactors. In this paper, firstly outline of group cross-section processing adopted in Prof. GROUCH-G/B system is described in detail which is a common step for all group cross-section library generation. Next available group cross-section libraries developed in Japan based on JENDL-3 are briefly reviewed. Lastly newly developed JSSTDL library system is presented with some special attention to the JENDL-3 data. (author)

Neutron-capture cross sections from indirect measurements

Directory of Open Access Journals (Sweden)

Scielzo N.D.

2012-02-01

Full Text Available Cross sections for compound-nuclear reactions reactions play an important role in models of astrophysical environments and simulations of the nuclear fuel cycle. Providing reliable cross section data remains a formidable task, and direct measurements have to be complemented by theoretical predictions and indirect methods. The surrogate nuclear reactions method provides an indirect approach for determining cross sections for reactions on unstable isotopes, which are difficult or impossible to measure otherwise. Current implementations of the method provide useful cross sections for (n,f reactions, but need to be improved upon for applications to capture reactions.

Curves and tables of neutron cross sections

International Nuclear Information System (INIS)

Nakagawa, Tsuneo; Asami, Tetsuo; Yoshida, Tadashi

1990-07-01

Neutron cross-section curves from the Japanese Evaluated Nuclear Data Library version 3, JENDL-3, are presented in both graphical and tabular form for users in a wide range of application areas in the nuclear energy field. The contents cover cross sections for all the main reactions induced by neutrons with an energy below 20 MeV including; total, elastic scattering, capture, and fission, (n,n'), (n,2n), (n,3n), (n,α), (n,p) reactions. The 2200 m/s cross-section values, resonance integrals, and Maxwellian- and fission-spectrum averaged cross sections are also tabulated. (author)

Null-polygonal minimal surfaces in AdS{sub 4} from perturbed W minimal models

Energy Technology Data Exchange (ETDEWEB)

Hatsuda, Yasuyuki [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ito, Katsushi [Tokyo Institute of Technology (Japan). Dept. of Physics; Satoh, Yuji [Tsukuba Univ., Sakura, Ibaraki (Japan). Inst. of Physics

2012-11-15

We study the null-polygonal minimal surfaces in AdS{sub 4}, which correspond to the gluon scattering amplitudes/Wilson loops in N=4 super Yang-Mills theory at strong coupling. The area of the minimal surfaces with n cusps is characterized by the thermodynamic Bethe ansatz (TBA) integral equations or the Y-system of the homogeneous sine-Gordon model, which is regarded as the SU(n-4){sub 4}/U(1){sup n-5} generalized parafermion theory perturbed by the weight-zero adjoint operators. Based on the relation to the TBA systems of the perturbed W minimal models, we solve the TBA equations by using the conformal perturbation theory, and obtain the analytic expansion of the remainder function around the UV/regular-polygonal limit for n = 6 and 7. We compare the rescaled remainder function for n=6 with the two-loop one, to observe that they are close to each other similarly to the AdS{sub 3} case.

Some solvable, and as yet unsolvable, polygon and walk models

International Nuclear Information System (INIS)

Guttmann, Anthony J

2006-01-01

One partly solvable and two solvable models of polygons are discussed. Using a simple transfer matrix approach Iwan Jensen has derived very long series expansions for the perimeter generating function of both three-choice polygons and punctured staircase polygons. In both cases it is found that all the terms in the generating function can be reproduced from a linear Fuchsian differential equation of order 8. We report on an analysis of the properties of the differential equations. Recently Enrica Duchi has discussed the problem of so-called prudent self-avoiding walks. We discuss the polygon analogue of this problem, and argue that the generating function for prudent polygons is unlikely to be differentiably finite, though a restricted version of the problem, called prudent polygons of the second type, is likely to be differentiably finite. The exact generating function for prudent polygons of the first type is also found

Neutron Cross Sections for Aluminium

Energy Technology Data Exchange (ETDEWEB)

Forsberg, Leif

1963-08-15

Total, elastic, inelastic, (n, 2n), (n, {alpha}), (n, p), and (n, {gamma}) cross sections for aluminium have been compiled from thermal to 100 MeV based upon literature search and theoretical interpolations and estimates. Differential elastic cross sections in the centre of mass system are represented by the Legendre coefficients. This method was chosen in order to obtain the best description of the energy dependence of the anisotropy.

High ET jet cross sections at CDF

International Nuclear Information System (INIS)

Flaugher, B.

1996-08-01

The inclusive jet cross section for p anti p collisions at √s = 1.8 TeV as measured by the CDF collaboration will be presented. Preliminary CDF measurements of the Σ E T cross section at √s = 1.8 TeV and the central inclusive jet cross section at √s = 0.630 TeV will also be shown

Recommended evaluation procedure for photonuclear cross section

Energy Technology Data Exchange (ETDEWEB)

Lee, Young-Ouk; Chang, Jonghwa; Fukahori, Tokio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-03-01

In order to generate photonuclear cross section library for the necessary applications, data evaluation is combined with theoretical evaluation, since photonuclear cross sections measured cannot provide all necessary data. This report recommends a procedure consisting of four steps: (1) analysis of experimental data, (2) data evaluation, (3) theoretical evaluation and, if necessary, (4) modification of results. In the stage of analysis, data obtained by different measurements are reprocessed through the analysis of their discrepancies to a representative data set. In the data evaluation, photonuclear absorption cross sections are evaluated via giant dipole resonance and quasi-deutron mechanism. With photoabsorption cross sections from the data evaluation, theoretical evaluation is applied to determine various decay channel cross sections and emission spectra using equilibrium and preequilibrium mechanism. After this, the calculated results are compared with measured data, and in some cases the results are modified to better describe measurements. (author)

Benefits of regular aerobic exercise for executive functioning in healthy populations.

Science.gov (United States)

Guiney, Hayley; Machado, Liana

2013-02-01

Research suggests that regular aerobic exercise has the potential to improve executive functioning, even in healthy populations. The purpose of this review is to elucidate which components of executive functioning benefit from such exercise in healthy populations. In light of the developmental time course of executive functions, we consider separately children, young adults, and older adults. Data to date from studies of aging provide strong evidence of exercise-linked benefits related to task switching, selective attention, inhibition of prepotent responses, and working memory capacity; furthermore, cross-sectional fitness data suggest that working memory updating could potentially benefit as well. In young adults, working memory updating is the main executive function shown to benefit from regular exercise, but cross-sectional data further suggest that task-switching and post error performance may also benefit. In children, working memory capacity has been shown to benefit, and cross-sectional data suggest potential benefits for selective attention and inhibitory control. Although more research investigating exercise-related benefits for specific components of executive functioning is clearly needed in young adults and children, when considered across the age groups, ample evidence indicates that regular engagement in aerobic exercise can provide a simple means for healthy people to optimize a range of executive functions.

Recommended activation detector cross sections (RNDL-82)

International Nuclear Information System (INIS)

Bondars, Kh.Ya.; Lapenas, A.A.

1984-01-01

The results of the comparison between measured and calculated average cross sections in 5 benchmark experiments are presented. Calculations have been based on the data from 10 libraries of evaluated cross sections. The recommended library (RNDL-82) of the activation detector cross sections has been created on the basis of the comparison. RNDL-82, including 26 reactions, and the basic characteristics of the detectors are presented. (author)

Activation cross section and isomeric cross section ratios for the (n ,2 n ) reaction on 153Eu

Science.gov (United States)

Luo, Junhua; Jiang, Li; Li, Suyuan

2017-10-01

The 153Eu(n ,2 n ) m1,m2,g152Eu cross section was measured by means of the activation technique at three neutron energies in the range 13-15 MeV. The quasimonoenergetic neutron beam was formed via the 3H(d ,n ) 4He reaction, in the Pd-300 Neutron Generator at the Chinese Academy of Engineering Physics (CAEP). The activities induced in the reaction products were measured using high-resolution γ-ray spectroscopy. The cross section of the population of the second high-spin (8-) isomeric state was measured along with the reaction cross section populating both the ground (3-) and the first isomeric state (0-). Cross sections were also evaluated theoretically using the numerical code TALYS-1.8, with different level density options at neutron energies varying from the reaction threshold to 20 MeV. Results are discussed and compared with the corresponding literature.

Decomposition of orthogonal polygons in a set of rectanglеs

OpenAIRE

Shestakov, E.; Voronov, A.

2009-01-01

Algorithm for covering orthogonal integrated circuit layout objects is considered. Objects of the research are special single-connected orthogonal polygons which are generated during decomposition of any multiply connected polygon in a set of single-connected orthogonal polygons. Developed algorithm for covering polygons based on the mathematical techinque of logic matrix transformation. Results described in this paper, can be applied in computer geometry and image analysis.

Activation cross section and isomeric cross-section ratio for the (n,2n) reaction on {sup 132,134}Ba

Energy Technology Data Exchange (ETDEWEB)

Luo, Junhua [Hexi Univ., Zhangye (China). School of Physics and Electromechanical Engineering; Hexi Univ., Zhangye (China). Inst. of New Energy; Wu, Chunlei; Jiang, Li [Chinese Academy of Engineering Physics, Mianyang (China). Inst. of Nuclear Physics and Chemistry; Li, Suyuan [Hexi Univ., Zhangye (China). Inst. of New Energy

2017-07-01

Cross sections of the {sup 132}Ba(n,2n){sup 131m,g}Ba and {sup 134}Ba(n,2n){sup 133m,g}Ba reactions and their isomeric cross section ratios σ{sub m}/σ{sub g} have been measured by means of the activation technique at three neutron energies in the range 13-15 MeV. BaCO{sub 3} samples and Nb monitor foils were activated together to determine the reaction cross section and the incident neutron flux. The quasimonoenergetic neutrons beam were produced via the {sup 3}H(d,n){sup 4}He reaction at the Pd-300 Neutron Generator of the Chinese Academy of Engineering Physics (CAEP). The activities induced in the reaction products were measured using high-resolution γ ray spectroscopy. The pure cross section of the ground-state was derived from the absolute cross section of the metastable state and the residual nuclear decay analysis. Cross sections were also evaluated theoretically using the numerical nuclear model code, TALYS-1.8 with different level density options at neutron energies varying from the reaction threshold to 20 MeV. Results are discussed and compared with the corresponding literature.

Parcels and Land Ownership - Volusia County Parcels (Polygons)

Data.gov (United States)

NSGIC Local Govt | GIS Inventory — Parcel Ownership Polygon Layer: Polygons showing property ownership created from the "master" subdivision base map for Volusia County. Multiple lots and parcels...

Dielectronic recombination cross sections for H-like ions

International Nuclear Information System (INIS)

Pindzola, M.S.; Badnell, N.R.; Griffin, D.C.

1990-01-01

Dielectronic recombination cross sections for several H-like atomic ions are calculated in an isolated-resonance, distorted-wave approximation. Fine-structure and configuration-interaction effects are examined in detail for the O 7+ cross section. Hartree-Fock, intermediate-coupled, multiconfiguration dielectronic recombination cross sections for O 7+ are then compared with the recent experimental measurements obtained with the Test Storage Ring in Heidelberg. The cross-section spectra line up well in energy and the shape of the main resonance structures are comparable. The experimental integrated cross sections differ by up to 20% from theory, but this may be due in part to uncertainties in the electron distribution function

Comparative analysis among several cross section sets

International Nuclear Information System (INIS)

Caldeira, A.D.

1983-01-01

Critical parameters were calculated using the one dimensional multigroup transport theory for several cross section sets. Calculations have been performed for water mixtures of uranium metal, plutonium metal and uranium-thorium oxide, and for metallics systems, to determine the critical dimensions of geometries (sphere and cylinder). For this aim, the following cross section sets were employed: 1) multigroup cross section sets obtained from the GAMTEC-II code; 2) the HANSEN-ROACH cross section sets; 3) cross section sets from the ENDF/B-IV, processed by the NJOY code. Finally, we have also calculated the corresponding critical radius using the one dimensional multigroup transport DTF-IV code. The numerical results agree within a few percent with the critical values obtained in the literature (where the greatest discrepancy occured in the critical dimensions of water mixtures calculated with the values generated by the NJOY code), a very good results in comparison with similar works. (Author) [pt

Entanglement complexity of semiflexible lattice polygons

International Nuclear Information System (INIS)

Orlandini, E; Tesi, M C; Whittington, S G

2005-01-01

We use Monte Carlo methods to study knotting in polygons on the simple cubic lattice with a stiffness fugacity. We investigate how the knot probability depends on stiffness and how the relative frequency of trefoils and figure eight knots changes as the stiffness changes. In addition, we examine the effect of stiffness on the writhe of the polygons. (letter to the editor)

Generating equilateral random polygons in confinement III

International Nuclear Information System (INIS)

Diao, Y; Ernst, C; Montemayor, A; Ziegler, U

2012-01-01

In this paper we continue our earlier studies (Diao et al 2011 J. Phys. A: Math. Theor. 44 405202, Diao et al J. Phys. A: Math. Theor. 45 275203) on the generation methods of random equilateral polygons confined in a sphere. The first half of this paper is concerned with the generation of confined equilateral random walks. We show that if the selection of a vertex is uniform subject to the position of its previous vertex and the confining condition, then the distributions of the vertices are not uniform, although there exists a distribution such that if the initial vertex is selected following this distribution, then all vertices of the random walk follow this same distribution. Thus in order to generate a confined equilateral random walk, the selection of a vertex cannot be uniform subject to the position of its previous vertex and the confining condition. We provide a simple algorithm capable of generating confined equilateral random walks whose vertex distribution is almost uniform in the confinement sphere. In the second half of this paper we show that any process generating confined equilateral random walks can be turned into a process generating confined equilateral random polygons with the property that the vertex distribution of the polygons approaches the vertex distribution of the walks as the polygons get longer and longer. In our earlier studies, the starting point of the confined polygon is fixed at the center of the sphere. The new approach here allows us to move the starting point of the confined polygon off the center of the sphere. (paper)

Inscribed polygons and Heron polynomials

International Nuclear Information System (INIS)

Varfolomeev, V V

2003-01-01

Heron's well-known formula expressing the area of a triangle in terms of the lengths of its sides is generalized in the following sense to polygons inscribed in a circle: it is proved that the area is an algebraic function of the lengths of the edges of the polygon. Similar results are proved for the diagonals and the radius of the circumscribed circle. The resulting algebraic equations are studied and elementary geometric applications of the algebraic results obtained are presented

Fission cross section measurements at intermediate energies

International Nuclear Information System (INIS)

Laptev, Alexander

2005-01-01

The activity in intermediate energy particle induced fission cross-section measurements of Pu, U isotopes, minor actinides and sub-actinides in PNPI of Russia is reviewed. The neutron-induced fission cross-section measurements are under way in the wide energy range of incident neutrons from 0.5 MeV to 200 MeV at the GNEIS facility. In number of experiments at the GNEIS facility, the neutron-induced fission cross sections were obtained for many nuclei. In another group of experiments the proton-induced fission cross-section have been measured for proton energies ranging from 200 to 1000 MeV at 100 MeV intervals using the proton beam of PNPI synchrocyclotron. (author)

Partial cross sections near the higher resonances

International Nuclear Information System (INIS)

Falk-Vairant, P.; Valladas, G.

1961-07-01

As a continuation of the report given at the 10. Rochester Conference, recent measurements of charge-exchange cross section and π 0 production in π - -p interactions are presented here. Section 1 gives a summary of the known results for the elastic, inelastic, and charge-exchange cross sections. Section 2 presents the behavior of the cross sections in the T=1/2 state, in order to discuss the resonances at 600 and 890 MeV. Section 3 discusses the charge-exchange scattering and the interference term between the T=1/2 and T=3/2 states. Section 4 presents some comments on inelastic processes. This report is reprinted from 'Reviews of Modern Physics', Vol. 33, No. 3, 362-367, July, 1961

Classical scattering cross section in sputtering transport theory

International Nuclear Information System (INIS)

Zhang Zhulin

2002-01-01

For Lindhard scaling interaction potential scattering commonly used in sputtering theory, the authors analyzed the great difference between Sigmund's single power and the double power cross sections calculated. The double power cross sections can give a much better approximation to the Born-Mayer scattering in the low energy region (m∼0.1). In particular, to solve the transport equations by K r -C potential interaction given by Urbassek few years ago, only the double power cross sections (m∼0.1) can yield better approximate results for the number of recoils. Therefore, the Sigmund's single power cross section might be replaced by the double power cross sections in low energy collision cascade theory

Measurement of e+e− → π+π− cross section at CMD-3

Directory of Open Access Journals (Sweden)

Logashenko I.B.

2014-05-01

Full Text Available Regular operation of the VEPP-2000 electron-positron collider started at the end of 2010 and about 60 pb−1 were collected so far by the CMD-3 detector in the whole available c.m. energy range from 0.32 GeV to 2.0 GeV. One of the main goals of the experiments at VEPP-2000 is a sub-percent measurement of the e+e− → π+π− cross-section. Here we present the overview of the data analysis techniques and the preliminary results of this measurement.

Fourier-transform infrared anisotropy in cross and parallel sections of tendon and articular cartilage

Directory of Open Access Journals (Sweden)

Bidthanapally Aruna

2008-10-01

Full Text Available Abstract Background Fourier Transform Infrared Imaging (FTIRI is used to investigate the amide anisotropies at different surfaces of a three-dimensional cartilage or tendon block. With the change in the polarization state of the incident infrared light, the resulting anisotropic behavior of the tissue structure is described here. Methods Thin sections (6 μm thick were obtained from three different surfaces of the canine tissue blocks and imaged at 6.25 μm pixel resolution. For each section, infrared imaging experiments were repeated thirteen times with the identical parameters except a 15° increment of the analyzer's angle in the 0° – 180° angular space. The anisotropies of amide I and amide II components were studied in order to probe the orientation of the collagen fibrils at different tissue surfaces. Results For tendon, the anisotropy of amide I and amide II components in parallel sections is comparable to that of regular sections; and tendon's cross sections show distinct, but weak anisotropic behavior for both the amide components. For articular cartilage, parallel sections in the superficial zone have the expected infrared anisotropy that is consistent with that of regular sections. The parallel sections in the radial zone, however, have a nearly isotropic amide II absorption and a distinct amide I anisotropy. Conclusion From the inconsistency in amide anisotropy between superficial to radial zone in parallel section results, a schematic model is used to explain the origins of these amide anisotropies in cartilage and tendon.

Cross section data for ionization of important cyanides

International Nuclear Information System (INIS)

Kaur, Jaspreet; Antony, Bobby

2015-01-01

Highlights: • Multi centre spherical complex optical potential formalism used to find the CS. • Effective method (CSP-ic) to derive ionization contribution from inelastic CS. • Result shows excellent accord with previous results and consistent behaviour. • Maiden attempt to find CS for many cyanide molecules. • Strong correlation observed between peak of ionization with target properties. - Abstract: This article presents cross section calculations for interactions of important cyanides with electrons possessing energies beginning from ionization threshold of the target molecule to 5 keV. These data are pursued to meet the ever increasing demand for cross sections by the relevant atomic and molecular community for modelling astrophysical, atmospheric and technological domains. The calculations have been executed using an amalgam of multi centre spherical complex optical potential (MSCOP) formalism and complex scattering potential-ionization contribution (CSP-ic) method. Cross sections are compared with experimental and theoretical data wherever available. Strong correlations are observed for the cross sections which affirms consistent and reliable cross sections. Isomeric effect has been interpreted using variation of cross section with structure and target properties. Our cross sections will be tabulated in atomic collision database for use in modelling various statistical and dynamical quantities.

Cross section data for ionization of important cyanides

Energy Technology Data Exchange (ETDEWEB)

Kaur, Jaspreet; Antony, Bobby, E-mail: bka.ism@gmail.com

2015-11-15

Highlights: • Multi centre spherical complex optical potential formalism used to find the CS. • Effective method (CSP-ic) to derive ionization contribution from inelastic CS. • Result shows excellent accord with previous results and consistent behaviour. • Maiden attempt to find CS for many cyanide molecules. • Strong correlation observed between peak of ionization with target properties. - Abstract: This article presents cross section calculations for interactions of important cyanides with electrons possessing energies beginning from ionization threshold of the target molecule to 5 keV. These data are pursued to meet the ever increasing demand for cross sections by the relevant atomic and molecular community for modelling astrophysical, atmospheric and technological domains. The calculations have been executed using an amalgam of multi centre spherical complex optical potential (MSCOP) formalism and complex scattering potential-ionization contribution (CSP-ic) method. Cross sections are compared with experimental and theoretical data wherever available. Strong correlations are observed for the cross sections which affirms consistent and reliable cross sections. Isomeric effect has been interpreted using variation of cross section with structure and target properties. Our cross sections will be tabulated in atomic collision database for use in modelling various statistical and dynamical quantities.

Accurate Cross Sections for Microanalysis

OpenAIRE

Rez, Peter

2002-01-01

To calculate the intensity of x-ray emission in electron beam microanalysis requires a knowledge of the energy distribution of the electrons in the solid, the energy variation of the ionization cross section of the relevant subshell, the fraction of ionizations events producing x rays of interest and the absorption coefficient of the x rays on the path to the detector. The theoretical predictions and experimental data available for ionization cross sections are limited mainly to K shells of a...

Polygon on Mars

Science.gov (United States)

2008-01-01

This image shows a small-scale polygonal pattern in the ground near NASA's Phoenix Mars Lander. This pattern is similar in appearance to polygonal structures in icy ground in the arctic regions of Earth. Phoenix touched down on the Red Planet at 4:53 p.m. Pacific Time (7:53 p.m. Eastern Time), May 25, 2008, in an arctic region called Vastitas Borealis, at 68 degrees north latitude, 234 degrees east longitude. This image was acquired by the Surface Stereo Imager shortly after landing. On the Phoenix mission calendar, landing day is known as Sol 0, the first Martian day of the mission. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

Criticality benchmark comparisons leading to cross-section upgrades

International Nuclear Information System (INIS)

Alesso, H.P.; Annese, C.E.; Heinrichs, D.P.; Lloyd, W.R.; Lent, E.M.

1993-01-01

For several years criticality benchmark calculations with COG. COG is a point-wise Monte Carlo code developed at Lawrence Livermore National Laboratory (LLNL). It solves the Boltzmann equation for the transport of neutrons and photons. The principle consideration in developing COG was that the resulting calculation would be as accurate as the point-wise cross-sectional data, since no physics computational approximations were used. The objective of this paper is to report on COG results for criticality benchmark experiments in concert with MCNP comparisons which are resulting in corrections an upgrades to the point-wise ENDL cross-section data libraries. Benchmarking discrepancies reported here indicated difficulties in the Evaluated Nuclear Data Livermore (ENDL) cross-sections for U-238 at thermal neutron energy levels. This led to a re-evaluation and selection of the appropriate cross-section values from several cross-section sets available (ENDL, ENDF/B-V). Further cross-section upgrades anticipated

Oscillatory behaviour of Rydberg state total cross sections in the collisions Ne+-He and He+-Ne

International Nuclear Information System (INIS)

Andresen, B.; Jensen, K.; Veje, E.

1976-01-01

The Ne + -He and He + -Ne collisions have been studied by means of optical spectrometry in the projectile energy range 10-150 keV. Very similar and regular oscillations in the Rydberg state total cross sections are found for HeI in both collisions and for singlet as well as triplet excitation. These oscillations are well described by the Rosenthal model. The HeI 4d sup(1,3)D states display two superimposed oscillations for center-of-mass collision energies above 6.4 keV. This is interpreted as the opening of a third exit channel, believed to be the HeI 4f sup(1,3)F. No, or very little structure is found in the Rydberg state total cross sections for HeII, NeI, NeII and NeIII levels. (Auth.)

A fast ergodic algorithm for generating ensembles of equilateral random polygons

Science.gov (United States)

Varela, R.; Hinson, K.; Arsuaga, J.; Diao, Y.

2009-03-01

Knotted structures are commonly found in circular DNA and along the backbone of certain proteins. In order to properly estimate properties of these three-dimensional structures it is often necessary to generate large ensembles of simulated closed chains (i.e. polygons) of equal edge lengths (such polygons are called equilateral random polygons). However finding efficient algorithms that properly sample the space of equilateral random polygons is a difficult problem. Currently there are no proven algorithms that generate equilateral random polygons with its theoretical distribution. In this paper we propose a method that generates equilateral random polygons in a 'step-wise uniform' way. We prove that this method is ergodic in the sense that any given equilateral random polygon can be generated by this method and we show that the time needed to generate an equilateral random polygon of length n is linear in terms of n. These two properties make this algorithm a big improvement over the existing generating methods. Detailed numerical comparisons of our algorithm with other widely used algorithms are provided.

Cross section homogenization analysis for a simplified Candu reactor

International Nuclear Information System (INIS)

Pounders, Justin; Rahnema, Farzad; Mosher, Scott; Serghiuta, Dumitru; Turinsky, Paul; Sarsour, Hisham

2008-01-01

The effect of using zero current (infinite medium) boundary conditions to generate bundle homogenized cross sections for a stylized half-core Candu reactor problem is examined. Homogenized cross section from infinite medium lattice calculations are compared with cross sections homogenized using the exact flux from the reference core environment. The impact of these cross section differences is quantified by generating nodal diffusion theory solutions with both sets of cross sections. It is shown that the infinite medium spatial approximation is not negligible, and that ignoring the impact of the heterogeneous core environment on cross section homogenization leads to increased errors, particularly near control elements and the core periphery. (authors)

Fission cross section measurements of actinides at LANSCE

Energy Technology Data Exchange (ETDEWEB)

Tovesson, Fredrik [Los Alamos National Laboratory; Laptev, Alexander B [Los Alamos National Laboratory; Hill, Tony S [INL

2010-01-01

Fission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications. By combining measurement at two LANSCE facilities, Lujan Center and the Weapons Neutron Research center (WNR), differential cross sections can be measured from sub-thermal energies up to 200 MeV. Incident neutron energies are determined using the time-of-flight method, and parallel-plate ionization chambers are used to measure fission cross sections relative to the {sup 235}U standard. Recent measurements include the {sup 233,238}U, {sup 239,242}Pu and {sup 243}Am neutron-induced fission cross sections. In this paper preliminary results for cross section data of {sup 243}Am and {sup 233}U will be presented.

Methodology series module 3: Cross-sectional studies

Directory of Open Access Journals (Sweden)

Maninder Singh Setia

2016-01-01

Full Text Available Cross-sectional study design is a type of observational study design. In a cross-sectional study, the investigator measures the outcome and the exposures in the study participants at the same time. Unlike in case–control studies (participants selected based on the outcome status or cohort studies (participants selected based on the exposure status, the participants in a cross-sectional study are just selected based on the inclusion and exclusion criteria set for the study. Once the participants have been selected for the study, the investigator follows the study to assess the exposure and the outcomes. Cross-sectional designs are used for population-based surveys and to assess the prevalence of diseases in clinic-based samples. These studies can usually be conducted relatively faster and are inexpensive. They may be conducted either before planning a cohort study or a baseline in a cohort study. These types of designs will give us information about the prevalence of outcomes or exposures; this information will be useful for designing the cohort study. However, since this is a 1-time measurement of exposure and outcome, it is difficult to derive causal relationships from cross-sectional analysis. We can estimate the prevalence of disease in cross-sectional studies. Furthermore, we will also be able to estimate the odds ratios to study the association between exposure and the outcomes in this design.

Methodology Series Module 3: Cross-sectional Studies.

Science.gov (United States)

Setia, Maninder Singh

2016-01-01

Cross-sectional study design is a type of observational study design. In a cross-sectional study, the investigator measures the outcome and the exposures in the study participants at the same time. Unlike in case-control studies (participants selected based on the outcome status) or cohort studies (participants selected based on the exposure status), the participants in a cross-sectional study are just selected based on the inclusion and exclusion criteria set for the study. Once the participants have been selected for the study, the investigator follows the study to assess the exposure and the outcomes. Cross-sectional designs are used for population-based surveys and to assess the prevalence of diseases in clinic-based samples. These studies can usually be conducted relatively faster and are inexpensive. They may be conducted either before planning a cohort study or a baseline in a cohort study. These types of designs will give us information about the prevalence of outcomes or exposures; this information will be useful for designing the cohort study. However, since this is a 1-time measurement of exposure and outcome, it is difficult to derive causal relationships from cross-sectional analysis. We can estimate the prevalence of disease in cross-sectional studies. Furthermore, we will also be able to estimate the odds ratios to study the association between exposure and the outcomes in this design.

Morphometric analysis of the arteries of Willis Polygon

Directory of Open Access Journals (Sweden)

Canaz Huseyin

2018-03-01

Full Text Available Objective: Willis polygon forms the basis of the arterial circulation of the cerebrum. Willis polygon is a vascular structure whom variations are not rare. Knowledge of the anatomy and preservation of its integrity is crucial for performing neurovascular surgery and intracranial tumour surgery. Because of the important vascular and neurological structures, approaches to this region are considered extremely risky. One of the main variations in-person basis is the diameter differences of the arteries, which forms Willis polygon, between the left and right hemispheres. About structure and variations, studies of Rhoton and Yasargil had formed the touchstone. Our aim is to contribute to the literature and clinical studies, to be done in the future, by comparing our results with previous studies about variations and morphometric features of Willis polygon.

Compilation of cross-sections. Pt. 1

International Nuclear Information System (INIS)

Flaminio, V.; Moorhead, W.G.; Morrison, D.R.O.; Rivoire, N.

1983-01-01

A compilation of integral cross-sections for hadronic reactions is presented. This is an updated version of CERN/HERA 79-1, 79-2, 79-3. It contains all data published up to the beginning of 1982, but some more recent data have also been included. Plots of the cross-sections versus incident laboratory momentum are also given. (orig.)

Compilation of cross-sections. Pt. 4

International Nuclear Information System (INIS)

Alekhin, S.I.; Ezhela, V.V.; Lugovsky, S.B.; Tolstenkov, A.N.; Yushchenko, O.P.; Baldini, A.; Cobal, M.; Flaminio, V.; Capiluppi, P.; Giacomelli, G.; Mandrioli, G.; Rossi, A.M.; Serra, P.; Moorhead, W.G.; Morrison, D.R.O.; Rivoire, N.

1987-01-01

This is the fourth volume in our series of data compilations on integrated cross-sections for weak, electromagnetic, and strong interaction processes. This volume covers data on reactions induced by photons, neutrinos, hyperons, and K L 0 . It contains all data published up to June 1986. Plots of the cross-sections versus incident laboratory momentum are also given. (orig.)

Geophysical Features - SILURIAN_REEF_POLYGONS_MM54_IN: Silurian Reef Locations in Indiana (Indiana Geological Survey, 1:500,000, Polygon Shapefile)

Data.gov (United States)

NSGIC State | GIS Inventory — SILURIAN_REEF_POLYGONS_MM54_IN is a polygon shapefile that shows the general locations of Silurian rock reef bank formations in Indiana. These data include two major...

Evaluation of fusion-evaporation cross-section calculations

Science.gov (United States)

Blank, B.; Canchel, G.; Seis, F.; Delahaye, P.

2018-02-01

Calculated fusion-evaporation cross sections from five different codes are compared to experimental data. The present comparison extents over a large range of nuclei and isotopic chains to investigate the evolution of experimental and calculated cross sections. All models more or less overestimate the experimental cross sections. We found reasonable agreement by using the geometrical average of the five model calculations and dividing the average by a factor of 11.2. More refined analyses are made for example for the 100Sn region.

NDS multigroup cross section libraries

International Nuclear Information System (INIS)

DayDay, N.

1981-12-01

A summary description and documentation of the multigroup cross section libraries which exist at the IAEA Nuclear Data Section are given in this report. The libraries listed are available either on tape or in printed form. (author)

Neutron-induced fission cross sections

International Nuclear Information System (INIS)

Weigmann, H.

1991-01-01

In the history of fission research, neutron-induced fission has always played the most important role. The practical importance of neutron-induced fission rests upon the fact that additional neutrons are produced in the fission process, and thus a chain reaction becomes possible. The practical applications of neutron-induced fission will not be discussed in this chapter, but only the physical properties of one of its characteristics, namely (n,f) cross sections. The most important early summaries on the subject are the monograph edited by Michaudon which also deals with the practical applications, the earlier review article on fission by Michaudon, and the review by Bjornholm and Lynn, in which neutron-induced fission receives major attention. This chapter will attempt to go an intermediate way between the very detailed theoretical treatment in the latter review and the cited monograph which emphasizes the applied aspects and the techniques of fission cross-section measurements. The more recent investigations in the field will be included. Section II will survey the properties of cross sections for neutron-induced fission and also address some special aspects of the experimental methods applied in their measurement. Section Ill will deal with the formal theory of neutron-induced nuclear reactions for the resolved resonance region and the region of statistical nuclear reactions. In Section IV, the fission width, or fission transmission coefficient, will be discussed in detail. Section V will deal with the broader structures due to incompletely damped vibrational resonances, and in particular will address the special case of thorium and neighboring isotopes. Finally, Section VI will briefly discuss parity violation effects in neutron-induced fission. 74 refs., 14 figs., 3 tabs

ENDF/B-5 fission product cross section evaluations

International Nuclear Information System (INIS)

Schenter, R.E.; England, T.R.

1979-12-01

Cross section evaluations were made for the 196 fission product nuclides on the ENDF/B-5 data files. Most of the evaluations involve updating the capture cross sections of the important absorbers for fast and thermal reactor systems. This included updating thermal values, resonance integrals, resonance parameter sets, and fast capture cross sections. For the fast capture results generalized least-squares calculations were made with the computer code FERRET. Input for these cross section adjustments included nuclear models calculations and both integral and differential experimental data results. The differential cross sections and their uncertainties were obtained from the CSIRS library. Integral measurement results came from CFRMF and STEK Assemblies 500, 1000, 2000, 3000, 4000. Comparisons of these evaluations with recent capture measurements are shown. 15 figures, 10 tables

Nuclear fission and neutron-induced fission cross-sections

Energy Technology Data Exchange (ETDEWEB)

James, G.D.; Lynn, J.E.; Michaudon, A.; Rowlands, J.; de Saussure, G.

1981-01-01

A general presentation of current knowledge of the fission process is given with emphasis on the low energy fission of actinide nuclei and neutron induced fission. The need for and the required accuracy of fission cross section data in nuclear energy programs are discussed. A summary is given of the steps involved in fission cross section measurement and the range of available techniques. Methods of fission detection are described with emphasis on energy dependent changed and detector efficiency. Examples of cross section measurements are given and data reduction is discussed. The calculation of fission cross sections is discussed and relevant nuclear theory including the formation and decay of compound nuclei and energy level density is introduced. A description of a practical computation of fission cross sections is given.

INJURIES IN DISC GOLF - A DESCRIPTIVE CROSS-SECTIONAL STUDY

DEFF Research Database (Denmark)

Rahbek, Martin Amadeus; Nielsen, Rasmus Oestergaard

2016-01-01

BACKGROUND: Disc golf is rapidly increasing in popularity and more than two million people are estimated to regularly participate in disc golf activities. Despite this popularity, the epidemiology of injuries in disc golf remains under reported. PURPOSE: The purpose of the present study...... was to investigate the prevalence and anatomic distribution of injuries acquired through disc-golf participation in Danish disc golf players. METHODS: The study was a cross-sectional study conducted on Danish disc-golf players. In May 2015, invitations to complete a web-based questionnaire were spread online via...... social media, and around disc-golf courses in Denmark. The questionnaire included questions regarding disc-golf participation and the characteristics of injuries acquired through disc golf participation. The data was analyzed descriptively. RESULTS: An injury prevalence of 13.3% (95% CI: 6.7% to 19...

Model cross section calculations using LAHET

International Nuclear Information System (INIS)

Prael, R.E.

1992-01-01

The current status of LAHET is discussed. The effect of a multistage preequilibrium exciton model following the INC is examined for neutron emission benchmark calculations, as is the use of a Fermi breakup model for light nuclei rather than an evaporation model. Comparisons are made also for recent fission cross section experiments, and a discussion of helium production cross sections is presented

Interference analysis of fission cross section

International Nuclear Information System (INIS)

Toshkov, S.A.; Yaneva, N.B.

1976-01-01

The formula for the reaction cross-section based on the R-matrix formalism considering the interference between the two neighbouring resonances, referred to the same value of total momentum was used for the analysis of the cross-section of resonance neutron induced fission of 230Pu. The experimental resolution and thermal motion of the target nuclei were accounted for numerical integration

Total cross sections for electron scattering by He

International Nuclear Information System (INIS)

De Heer, F.J.; Jansen, R.H.J.

1977-01-01

A set of total cross sections for scattering of electrons by He has been evaluated over the energy range of zero to 3000 eV by means of the analysis of experiments and theories on total cross sections for elastic scattering, ionisation and excitation, and on differential cross sections for elastic and inelastic scattering. Between 0 and 19.8 eV, where no inelastic processes occur, the total cross sections for scattering are equal to those for elastic scattering. Above 19.8 eV total cross sections for scattering of electrons have been evaluated by adding those for ionisation, excitation and elastic scattering. The total cross sections thus obtained are probably accurate to about 5% over a large part of the energy range. They appear to be in very good agreement with the recent experimental results of Blaauw et al. (J. Phys. B.; 10:L299 (1977)). The present results have already proved useful for application in the dispersion relation for forward scattering in electron-helium collisions. (author)

Cross Sections for Inner-Shell Ionization by Electron Impact

Energy Technology Data Exchange (ETDEWEB)

Llovet, Xavier, E-mail: xavier@ccit.ub.edu [Centres Científics i Tecnològics, Universitat de Barcelona, Lluís Solé i Sabarís 1-3, 08028 Barcelona (Spain); Powell, Cedric J. [Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8370 (United States); Salvat, Francesc [Facultat de Física (ECM and ICC), Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Jablonski, Aleksander [Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw (Poland)

2014-03-15

An analysis is presented of measured and calculated cross sections for inner-shell ionization by electron impact. We describe the essentials of classical and semiclassical models and of quantum approximations for computing ionization cross sections. The emphasis is on the recent formulation of the distorted-wave Born approximation by Bote and Salvat [Phys. Rev. A 77, 042701 (2008)] that has been used to generate an extensive database of cross sections for the ionization of the K shell and the L and M subshells of all elements from hydrogen to einsteinium (Z = 1 to Z = 99) by electrons and positrons with kinetic energies up to 1 GeV. We describe a systematic method for evaluating cross sections for emission of x rays and Auger electrons based on atomic transition probabilities from the Evaluated Atomic Data Library of Perkins et al. [Lawrence Livermore National Laboratory, UCRL-ID-50400, 1991]. We made an extensive comparison of measured K-shell, L-subshell, and M-subshell ionization cross sections and of Lα x-ray production cross sections with the corresponding calculated cross sections. We identified elements for which there were at least three (for K shells) or two (for L and M subshells) mutually consistent sets of cross-section measurements and for which the cross sections varied with energy as expected by theory. The overall average root-mean-square deviation between the measured and calculated cross sections was 10.9% and the overall average deviation was −2.5%. This degree of agreement between measured and calculated ionization and x-ray production cross sections was considered to be very satisfactory given the difficulties of these measurements.

Two generalizations of column-convex polygons

International Nuclear Information System (INIS)

Feretic, Svjetlan; Guttmann, Anthony J

2009-01-01

Column-convex polygons were first counted by area several decades ago, and the result was found to be a simple, rational, generating function. In this work we generalize that result. Let a p-column polyomino be a polyomino whose columns can have 1, 2, ..., p connected components. Then column-convex polygons are equivalent to 1-convex polyominoes. The area generating function of even the simplest generalization, namely 2-column polyominoes, is unlikely to be solvable. We therefore define two classes of polyominoes which interpolate between column-convex polygons and 2-column polyominoes. We derive the area generating functions of those two classes, using extensions of existing algorithms. The growth constants of both classes are greater than the growth constant of column-convex polyominoes. Rather tight lower bounds on the growth constants complement a comprehensive asymptotic analysis.

Self-assembly of Archimedean tilings with enthalpically and entropically patchy polygons.

Science.gov (United States)

Millan, Jaime A; Ortiz, Daniel; van Anders, Greg; Glotzer, Sharon C

2014-03-25

Considerable progress in the synthesis of anisotropic patchy nanoplates (nanoplatelets) promises a rich variety of highly ordered two-dimensional superlattices. Recent experiments of superlattices assembled from nanoplates confirm the accessibility of exotic phases and motivate the need for a better understanding of the underlying self-assembly mechanisms. Here, we present experimentally accessible, rational design rules for the self-assembly of the Archimedean tilings from polygonal nanoplates. The Archimedean tilings represent a model set of target patterns that (i) contain both simple and complex patterns, (ii) are comprised of simple regular shapes, and (iii) contain patterns with potentially interesting materials properties. Via Monte Carlo simulations, we propose a set of design rules with general applicability to one- and two-component systems of polygons. These design rules, specified by increasing levels of patchiness, correspond to a reduced set of anisotropy dimensions for robust self-assembly of the Archimedean tilings. We show for which tilings entropic patches alone are sufficient for assembly and when short-range enthalpic interactions are required. For the latter, we show how patchy these interactions should be for optimal yield. This study provides a minimal set of guidelines for the design of anisostropic patchy particles that can self-assemble all 11 Archimedean tilings.

Floodplain Cross Section Lines

Data.gov (United States)

Department of Homeland Security — This table is required for any Digital Flood Insurance Rate Map database where cross sections are shown on the Flood Insurance Rate Map (FIRM). Normally any FIRM...

A Pebble Bed Reactor cross section methodology

International Nuclear Information System (INIS)

Hudson, Nathanael H.; Ougouag, Abderrafi M.; Rahnema, Farzad; Gougar, Hans

2009-01-01

A method is presented for the evaluation of microscopic cross sections for the Pebble Bed Reactor (PBR) neutron diffusion computational models during convergence to an equilibrium (asymptotic) fuel cycle. This method considers the isotopics within a core spectral zone and the leakages from such a zone as they arise during reactor operation. The randomness of the spatial distribution of fuel grains within the fuel pebbles and that of the fuel and moderator pebbles within the core, the double heterogeneity of the fuel, and the indeterminate burnup of the spectral zones all pose a unique challenge for the computation of the local microscopic cross sections. As prior knowledge of the equilibrium composition and leakage is not available, it is necessary to repeatedly re-compute the group constants with updated zone information. A method is presented to account for local spectral zone composition and leakage effects without resorting to frequent spectrum code calls. Fine group data are pre-computed for a range of isotopic states. Microscopic cross sections and zone nuclide number densities are used to construct fine group macroscopic cross sections, which, together with fission spectra, flux modulation factors, and zone buckling, are used in the solution of the slowing down balance to generate a new or updated spectrum. The microscopic cross-sections are then re-collapsed with the new spectrum for the local spectral zone. This technique is named the Spectral History Correction (SHC) method. It is found that this method accurately recalculates local broad group microscopic cross sections. Significant improvement in the core eigenvalue, flux, and power peaking factor is observed when the local cross sections are corrected for the effects of the spectral zone composition and leakage in two-dimensional PBR test problems.

Transport cross section for small-angle scattering

International Nuclear Information System (INIS)

D'yakonov, M.I.; Khaetskii, A.V.

1991-01-01

Classical mechanics is valid for describing potential scattering under the conditions (1) λ much-lt α and (2) U much-gt ℎυ/α, where λ is the de Broglie wavelength, α is the characteristic size of the scatterer, U is the characteristic value of the potential energy, and υ is the velocity of the scattered particle. The second of these conditions means that the typical value of the classical scattering angle is far larger than the diffraction angle λ/α. In this paper the authors show that this second condition need not hold in a derivation of the transport cross section. In other words, provided that the condition λ much-lt α holds, it is always possible to calculate the transport cross section from the expressions of classical mechanics, even in the region U approx-lt ℎυ/α, where the scattering is diffractive,and the differential cross section is greatly different from the classical cross section. The transport cross section is found from the classical expression even in the anticlassical case U much-lt ℎυ/α, where the Born approximation can be used

Nonelastic-scattering cross sections of elemental nickel

International Nuclear Information System (INIS)

Smith, A.B.; Guenther, P.T.; Whalen, J.F.

1980-06-01

Neutron total cross sections of elemental nickel were measured from 1.3 to 4.5 MeV, at intervals of approx. 50 keV, with resolutions of 30 to 50 keV and to accuracies of 1 to 2.5%. Neutron differential-elastic-scattering cross sections were measured from 1.45 to 3.8 MeV, at intervals and with resolutions comparable to those of the total cross sections, and to accuracies of 3 to 5%. The nonelastic-scattering cross section is derived from the measured values to accuracies of greater than or equal to 6%. The experimental results are compared with previously reported values as represented by ENDF/B-V, and areas of consistency and discrepancy, noted. The measured results are shown to be in good agreement with the predictions of a model previously reported by the authors. 4 figures, 1 table

A consistent formulation of wave propagation and conversion in low aspect ratio tokamaks with non-circular cross section

International Nuclear Information System (INIS)

Cuperman, S.; Bruma, C.; Komoshvili, K.

1999-01-01

The authors developed a consistent formalism for the full wave equation, appropriate for the study of propagation, absorption and wave conversion of externally launched waves in strongly toroidal, spherical tokamaks with non-circular cross-section. This includes also the formulation of rigorous regularity, boundary, gauge and periodicity conditions suitable for the exact solution of the wave equation for such devices

Fragmentation cross sections outside the limiting-fragmentation regime

CERN Document Server

Sümmerer, K

2003-01-01

The empirical parametrization of fragmentation cross sections, EPAX, has been successfully applied to estimate fragment production cross sections in reactions of heavy ions at high incident energies. It is checked whether a similar parametrization can be found for proton-induced spallation around 1 GeV, the range of interest for ISOL-type RIB facilities. The validity of EPAX for medium-energy heavy-ion induced reactions is also checked. Only a few datasets are available, but in general EPAX predicts the cross sections rather well, except for fragments close to the projectile, where the experimental cross sections are found to be larger.

Exact generating function for 2-convex polygons

International Nuclear Information System (INIS)

James, W R G; Jensen, I; Guttmann, A J

2008-01-01

Polygons are described as almost-convex if their perimeter differs from the perimeter of their minimum bounding rectangle by twice their 'concavity index', m. Such polygons are called m-convex polygons and are characterized by having up to m indentations in their perimeter. We first describe how we conjectured the (isotropic) generating function for the case m = 2 using a numerical procedure based on series expansions. We then proceed to prove this result for the more general case of the full anisotropic generating function, in which steps in the x and y directions are distinguished. In doing so, we develop tools that would allow for the case m > 2 to be studied

Measurements of fission cross-sections. Chapter 4

International Nuclear Information System (INIS)

James, G.D.

1981-01-01

The steps involved in the measurement of fission cross sections are summarized and the range of techniques available are considered. Methods of fission detection are described with particular emphasis on the neutron energy dependent properties of the fission process and the details of fragment energy loss which can lead to energy-dependent changes in detector efficiency. Selected examples of fission cross-section measurements are presented and methods of data reduction, storage, analysis and evaluation, are examined. Finally requested accuracies for fission cross section data are compared to estimated available accuracies. (U.K.)

Vibrational enhancement of total breakup cross sections

International Nuclear Information System (INIS)

Haftel, M.I.; Lim, T.K.

1984-01-01

This paper considers the role of multi-two-body bound states, namely vibrational excitations, on total three-body breakup cross-sections. Total cross-sections are usually easy to measure, and they play a fundamental role in chemical kinetics. (orig.)

Target dependence of K+-nucleus total cross sections

International Nuclear Information System (INIS)

Jiang, M.F.; Ernst, D.J.; Chen, C.M.

1995-01-01

We investigate the total cross section and its target dependence for K + -nucleus scattering using a relativistic momentum-space optical potential model which incorporates relativistically normalized wave functions, invariant two-body amplitudes, covariant kinematics, and an exact full-Fermi averaging integral. The definition of the total cross section in the presence of a Coulomb interaction is reviewed and the total cross section is calculated in a way that is consistent with what is extracted from experiment. In addition, the total cross sections for a nucleus and for the deuteron are calculated utilizing the same theory. This minimizes the dependence of the ratio of these cross sections on the details of the theory. The model dependence of the first-order optical potential calculations is investigated. The theoretical results are found to be systematically below all existing data

Tables of RCN-2 fission-product cross section evaluation

International Nuclear Information System (INIS)

Gruppelaar, H.

1979-05-01

This report (continuation of ECN-13 and ECN-33) describes the third part of the RCN-2 evaluation of neutron cross sections for fission product nuclides in KEDAK format. It contains evaluated data for nine nuclides, i.e. 142 Nd, 143 Nd, 144 Nd, 145 Nd, 146 Nd, 147 Nd, 148 Nd, 150 Nd and 147 Pm. Most emphasis has been given to the evaluation of the radiative capture cross section, in order to provide a data base for adjustment calculations using results of integral measurements. Short evaluation reports are given for this cross section. The evaluated capture cross sections are compared with recent experimental differential and integral data. Graphs are given of the capture cross sections at neutron energies above 1 keV, in which also adjusted point cross sections, based upon integral STEK and CFRMF data have been plotted. Moreover, the results are compared with those of the well-known ENDF/B-IV evaluation for fission product nucleides. Finally, evaluation summaries are given, which include tables of other important neutron cross sections, such as the total, elastic scattering and inelastic scattering cross sections

A subtraction scheme for computing QCD jet cross sections at NNLO: integrating the subtraction terms I

Science.gov (United States)

Somogyi, Gábor; Trócsányi, Zoltán

2008-08-01

In previous articles we outlined a subtraction scheme for regularizing doubly-real emission and real-virtual emission in next-to-next-to-leading order (NNLO) calculations of jet cross sections in electron-positron annihilation. In order to find the NNLO correction these subtraction terms have to be integrated over the factorized unresolved phase space and combined with the two-loop corrections. In this paper we perform the integration of all one-parton unresolved subtraction terms.

Microscopic cross sections: An utopia?

Energy Technology Data Exchange (ETDEWEB)

Hilaire, S. [CEA Bruyeres-le-Chatel, DIF 91 (France); Koning, A.J. [Nuclear Research and Consultancy Group, PO Box 25, 1755 ZG Petten (Netherlands); Goriely, S. [Institut d' Astronomie et d' Astrophysique, Universite Libre de Bruxelles, Campus de la Plaine, CP 226, 1050 Brussels (Belgium)

2010-07-01

The increasing need for cross sections far from the valley of stability poses a challenge for nuclear reaction models. So far, predictions of cross sections have relied on more or less phenomenological approaches, depending on parameters adjusted to available experimental data or deduced from systematical relations. While such predictions are expected to be reliable for nuclei not too far from the experimentally known regions, it is clearly preferable to use more fundamental approaches, based on sound physical bases, when dealing with very exotic nuclei. Thanks to the high computer power available today, all major ingredients required to model a nuclear reaction can now be (and have been) microscopically (or semi-microscopically) determined starting from the information provided by a nucleon-nucleon effective interaction. We have implemented all these microscopic ingredients in the TALYS nuclear reaction code, and we are now almost able to perform fully microscopic cross section calculations. The quality of these ingredients and the impact of using them instead of the usually adopted phenomenological parameters will be discussed. (authors)

Microscopic cross sections: An utopia?

International Nuclear Information System (INIS)

Hilaire, S.; Koning, A.J.; Goriely, S.

2010-01-01

The increasing need for cross sections far from the valley of stability poses a challenge for nuclear reaction models. So far, predictions of cross sections have relied on more or less phenomenological approaches, depending on parameters adjusted to available experimental data or deduced from systematical relations.While such predictions are expected to be reliable for nuclei not too far from the experimentally known regions, it is clearly preferable to use more fundamental approaches, based on sound physical bases, when dealing with very exotic nuclei. Thanks to the high computer power available today, all major ingredients required to model a nuclear reaction can now be (and have been) microscopically (or semi-microscopically) determined starting from the information provided by a nucleon-nucleon effective interaction. We have implemented all these microscopic ingredients in the TALYS nuclear reaction code, and we are now almost able to perform fully microscopic cross section calculations. The quality of these ingredients and the impact of using them instead of the usually adopted phenomenological parameters will be discussed. (authors)

Accelerating Generalized Polygon Beams and Their Propagation

International Nuclear Information System (INIS)

Zhang Yun-Tian; Zhang Zhi-Gang; Cheng Teng; Zhang Qing-Chuan; Wu Xiao-Ping

2015-01-01

Accelerating beams with intensity cusps and exotic topological properties are drawing increasing attention as they have extensive uses in many intriguing fields. We investigate the structural features of accelerating polygon beams, show their generalized mathematical form theoretically, and discuss the even-numbered polygon beams. Furthermore, we also carry out the experiment and observe the intensity evolution during their propagation

Multilevel parametrization of fissile nuclei resonance cross sections

International Nuclear Information System (INIS)

Lukyanov, A.A.; Kolesov, V.V.; Janeva, N.

1987-01-01

Because the resonance interference has an important influence on the resonance structure of neutron cross sections energy dependence at lowest energies, multilevel scheme of the cross section parametrization which take into account the resonance interference is used for the description with the same provisions in the regions of the interferential maximum and minimum of the resonance cross sections of the fissile nuclei

Total and ionization cross sections of electron scattering by fluorocarbons

International Nuclear Information System (INIS)

Antony, B K; Joshipura, K N; Mason, N J

2005-01-01

Electron impact total cross sections (50-2000 eV) and total ionization cross sections (threshold to 2000 eV) are calculated for typical plasma etching molecules CF 4 , C 2 F 4 , C 2 F 6 , C 3 F 8 and CF 3 I and the CF x (x 1-3) radicals. The total elastic and inelastic cross sections are determined in the spherical complex potential formalism. The sum of the two gives the total cross section and the total inelastic cross section is used to calculate the total ionization cross sections. The present total and ionization cross sections are found to be consistent with other theories and experimental measurements, where they exist. Our total cross section results for CF x (x = 1-3) radicals presented here are first estimates on these species

Calculation of atom displacement cross section for structure material

International Nuclear Information System (INIS)

Liu Ping; Xu Yiping

2015-01-01

The neutron radiation damage in material is an important consideration of the reactor design. The radiation damage of materials mainly comes from atom displacements of crystal structure materials. The reaction cross sections of charged particles, cross sections of displacements per atom (DPA) and KERMA are the basis of radiation damage calculation. In order to study the differences of DPA cross sections with different codes and different evaluated nuclear data libraries, the DPA cross sections for structure materials were calculated with UNF and NJOY codes, and the comparisons of results were given. The DPA cross sections from different evaluated nuclear data libraries were compared. And the comparison of DPA cross sections between NJOY and Monte Carlo codes was also done. The results show that the differences among these evaluated nuclear data libraries exist. (authors)

Utilitarian cycling in Belgium: a cross-sectional study in a sample of regular cyclists.

OpenAIRE

de Geus, B.; Degraeuwe, B.; Vandenbulcke, G.; INT PANIS, Luc; Thomas, I.; Aertsens, Joris; De Weerdt, Y.; Torfs, R.; Meeusen, R.

2014-01-01

Background: For an accurate estimation of health benefits and hazards of utilitarian cycling, a prospective collection of bicycle usage data (exposure) is fundamental. Individual and environmental correlates are necessary to guide health promotion and traffic safety issues. Firstly, this study aims to report on utilitarian bicycle usage in Belgium, using a prospective data collection in regular adult commuter cyclists. Secondly, the association is explored between the individual variation in ...

The unusual asymptotics of three-sided prudent polygons

International Nuclear Information System (INIS)

Beaton, Nicholas R; Guttmann, Anthony J; Flajolet, Philippe

2010-01-01

We have studied the area-generating function of prudent polygons on the square lattice. Exact solutions are obtained for the generating function of two-sided and three-sided prudent polygons, and a functional equation is found for four-sided prudent polygons. This is used to generate series coefficients in polynomial time, and these are analysed to determine the asymptotics numerically. A careful asymptotic analysis of the three-sided polygons produces a most surprising result. A transcendental critical exponent is found, and the leading amplitude is not quite a constant, but is a constant plus a small oscillatory component with an amplitude approximately 10 -8 times that of the leading amplitude. This effect cannot be seen by any standard numerical analysis, but it may be present in other models. If so, it changes our whole view of the asymptotic behaviour of lattice models. (fast track communication)

Preparation of next generation set of group cross sections. 3

International Nuclear Information System (INIS)

Kaneko, Kunio

2002-03-01

This fiscal year, based on the examination result about the evaluation energy range of heavy element unresolved resonance cross sections, the upper energy limit of the energy range, where ultra-fine group cross sections are produced, was raised to 50 keV, and an improvement of the group cross section processing system was promoted. At the same time, reflecting the result of studies carried out till now, a function producing delayed neutron data was added to the general-purpose group cross section processing system , thus the preparation of general purpose group cross section processing system has been completed. On the other hand, the energy structure, data constitution and data contents of next generation group cross section set were determined, and the specification of a 151 groups next generation group cross section set was defined. Based on the above specification, a concrete library format of the next generation cross section set has been determined. After having carried out the above-described work, using the general-purpose group cross section processing system , which was complete in this study, with use of the JENDL-3. 2 evaluated nuclear data, the 151 groups next generation group cross section of 92 nuclides and the ultra fine group resonance cross section library for 29 nuclides have been prepared. Utilizing the 151 groups next generation group cross section set and the ultra-fine group resonance cross-section library, a bench mark test calculation of fast reactors has been performed by using an advanced lattice calculation code. It was confirmed, by comparing the calculation result with a calculation result of continuous energy Monte Carlo code, that the 151 groups next generation cross section set has sufficient accuracy. (author)

Positive Scattering Cross Sections using Constrained Least Squares

International Nuclear Information System (INIS)

Dahl, J.A.; Ganapol, B.D.; Morel, J.E.

1999-01-01

A method which creates a positive Legendre expansion from truncated Legendre cross section libraries is presented. The cross section moments of order two and greater are modified by a constrained least squares algorithm, subject to the constraints that the zeroth and first moments remain constant, and that the standard discrete ordinate scattering matrix is positive. A method using the maximum entropy representation of the cross section which reduces the error of these modified moments is also presented. These methods are implemented in PARTISN, and numerical results from a transport calculation using highly anisotropic scattering cross sections with the exponential discontinuous spatial scheme is presented

Heisenberg rise of total cross sections

International Nuclear Information System (INIS)

Ezhela, V.V.; Yushchenko, O.P.

1988-01-01

It is shown that on the basis of the original idea of Heisenberg on the quasiclassical picture of extended particle interactions one can construct a satisfactory description of the total cross sections, elastic cross sections, elastic diffractive slopes and mean charged multiplicities in the cm energy range from 5 to 900 GeV, and produce reasonable extrapolations up to several tens of TeV. 14 refs.; 7 figs.; 2 tabs

Calculating the Areas of Polygons with a Smartphone Light Sensor

Science.gov (United States)

Kapucu, Serkan; Simsek, Mertkan; Öçal, Mehmet Fatih

2017-01-01

This study explores finding the areas of polygons with a smartphone light sensor. A square and an irregular pentagon were chosen as our polygons. During the activity, the LED light was placed at the vertices of our polygons, and the illuminance values of this LED light were detected by the smartphone light sensor. The smartphone was placed on a…

FENDL/E-2.0. Evaluated nuclear data library of neutron-nucleus interaction cross sections and photon production cross sections and photon-atom interaction cross sections for fusion applications. Version 1, March 1997. Summary documentation

International Nuclear Information System (INIS)

Pashchenko, A.B.; Wienke, H.

1998-01-01

This document presents the description of a physical tape containing the basic evaluated nuclear data library of neutron-nucleus interaction cross sections, photon production cross sections and photon-atom interaction cross sections for fusion applications. It is part of the evaluated nuclear data library for fusion applications FENDL-2. The data are available cost-free from the Nuclear Data Section upon request. The data can also be retrieved by the user via online access through international computer networks. (author)

Polygonal Prism Mesh in the Viscous Layers for the Polyhedral Mesh Generator, PolyGen

International Nuclear Information System (INIS)

Lee, Sang Yong; Park, Chan Eok; Kim, Shin Whan

2015-01-01

Polyhedral mesh has been known to have some benefits over the tetrahedral mesh. Efforts have been made to set up a polyhedral mesh generation system with open source programs SALOME and TetGen. The evaluation has shown that the polyhedral mesh generation system is promising. But it is necessary to extend the capability of the system to handle the viscous layers to be a generalized mesh generator. A brief review to the previous works on the mesh generation for the viscous layers will be made in section 2. Several challenging issues for the polygonal prism mesh generation will be discussed as well. The procedure to generate a polygonal prism mesh will be discussed in detail in section 3. Conclusion will be followed in section 4. A procedure to generate meshes in the viscous layers with PolyGen has been successfully designed. But more efforts have to be exercised to find the best way for the generating meshes for viscous layers. Using the extrusion direction of the STL data will the first of the trials in the near future

Section Level Public Land Survey - polygons

Data.gov (United States)

Minnesota Department of Natural Resources — Public Land Survey line delineations to the section level. Data are derived primarily from Section corner locations captured from paper USGS seven and one-half...

Average size of random polygons with fixed knot topology.

Science.gov (United States)

Matsuda, Hiroshi; Yao, Akihisa; Tsukahara, Hiroshi; Deguchi, Tetsuo; Furuta, Ko; Inami, Takeo

2003-07-01

We have evaluated by numerical simulation the average size R(K) of random polygons of fixed knot topology K=,3(1),3(1) musical sharp 4(1), and we have confirmed the scaling law R(2)(K) approximately N(2nu(K)) for the number N of polygonal nodes in a wide range; N=100-2200. The best fit gives 2nu(K) approximately 1.11-1.16 with good fitting curves in the whole range of N. The estimate of 2nu(K) is consistent with the exponent of self-avoiding polygons. In a limited range of N (N greater, similar 600), however, we have another fit with 2nu(K) approximately 1.01-1.07, which is close to the exponent of random polygons.

Modelisation of the fission cross section

International Nuclear Information System (INIS)

Morariu, Claudia

2013-03-01

The neutron cross sections of four nuclear systems (n+ 235 U, n+ 233 U, n+ 241 Am and n+ 237 Np) are studied in the present document. The target nuclei of the first case, like 235 U and 239 Pu, have a large fission cross section after the absorption of thermal neutrons. These nuclei are called 'fissile' nuclei. The other type of nuclei, like 237 Np and 241 Am, fission mostly with fast neutrons, which exceed the fission threshold energy. These types of nuclei are called 'fertile'. The compound nuclei of the fertile nuclei have a binding energy higher than the fission barrier, while for the fissile nuclei the binding energy is lower than the fission barrier. In this work, the neutron induced cross sections for both types of nuclei are evaluated in the fast energy range. The total, reaction and shape-elastic cross sections are calculated by the coupled channel method of the optical model code ECIS, while the compound nucleus mechanism are treated by the statistical models implemented in the codes STATIS, GNASH and TALYS. The STATIS code includes a refined model of the fission process. Results from the theoretical calculations are compared with data retrieved from the experimental data base EXFOR. (author) [fr

Cross sections for hadron and lepton production processes

International Nuclear Information System (INIS)

Bhattacharya, R.

1976-01-01

Charged heavy lepton production in proton-proton collisions is studied. Motivated by recent experimental results from the Stanford Linear Accelerator Center a parton model analysis is given of the reaction p + p → L + + L - + x → μ +- + e/ -+ / + neutrinos + x. Results are presented for the total cross section and the differential cross sections with respect to the invariant mass squared of the final charged leptons and the transverse momenta of each one of them. The two-photon mechanism for pair production in colliding beam exeriments is considered. Through the use of mapped invariant integration variables, a reliable exact numerical calculation of the cross section for the production of muon and pion pairs by the two-photon mechanism is provided. Results are given for the exact total cross sections and also the differential cross sections with respect to the invariant mass squared of the pair. These are compared to the results obtained from the equivalent photon approximation method

Total reaction cross sections and neutron-removal cross sections of neutron-rich light nuclei measured by the COMBAS fragment-separator

Science.gov (United States)

Hue, B. M.; Isataev, T.; Erdemchimeg, B.; Artukh, A. G.; Aznabaev, D.; Davaa, S.; Klygin, S. A.; Kononenko, G. A.; Khuukhenkhuu, G.; Kuterbekov, K.; Lukyanov, S. M.; Mikhailova, T. I.; Maslov, V. A.; Mendibaev, K.; Sereda, Yu M.; Penionzhkevich, Yu E.; Vorontsov, A. N.

2017-12-01

Preliminary results of measurements of the total reaction cross sections σR and neutron removal cross section σ-xn for weakly bound 6He, 8Li, 9Be and 10Be nuclei at energy range (20-35) A MeV with 28Si target is presented. The secondary beams of light nuclei were produced by bombardment of the 22Ne (35 A MeV) primary beam on Be target and separated by COMBAS fragment-separator. In dispersive focal plane a horizontal slit defined the momentum acceptance as 1% and a wedge degrader of 200 μm Al was installed. The Bρ of the second section of the fragment-separator was adjusted for measurements in energy range (20-35) A MeV. Two-neutron removal cross sections for 6He and 10Be and one -neutron removal cross sections 8Li and 9Be were measured.

Microscopic cross-section measurements by thermal neutron activation

International Nuclear Information System (INIS)

Avila L, J.

1987-08-01

Microscopic cross sections measured by thermal neutron activation using RP-0 reactor at the Peruvian Nuclear Energy Institute. The method consists in measuring microscopic cross section ratios through activated samples, requiring being corrected in thermal and epithermal energetic range by Westcott formalism. Furthermore, the comptage ratios measured for each photopeak to its decay fraction should be normalized from interrelation between both processes above, activation microscopic cross sections are obtained

Distorted eikonal cross sections: A time-dependent view

International Nuclear Information System (INIS)

Turner, R.E.

1982-01-01

For Hamiltonians with two potentials, differential cross sections are written as time-correlation functions of reference and distorted transition operators. Distorted eikonal differential cross sections are defined in terms of straight-line and reference classical trajectories. Both elastic and inelastic results are obtained. Expressions for the inelastic cross sections are presented in terms of time-ordered cosine and sine memory functions through the use of the Zwanzig-Feshbach projection-operator method

Discussion of electron cross sections for transport calculations

International Nuclear Information System (INIS)

Berger, M.J.

1983-01-01

This paper deals with selected aspects of the cross sections needed as input for transport calculations and for the modeling of radiation effects in biological materials. Attention is centered mainly on the cross sections for inelastic interactions between electrons and water molecules and the use of these cross sections for the calculation of energy degradation spectra and of ionization and excitation yields. 40 references, 3 figures, 1 table

Tachyonic ionization cross sections of hydrogenic systems

Energy Technology Data Exchange (ETDEWEB)

Tomaschitz, Roman [Department of Physics, Hiroshima University, 1-3-1 Kagami-yama, Higashi-Hiroshima 739-8526 (Japan)

2005-03-11

Transition rates for induced and spontaneous tachyon radiation in hydrogenic systems as well as the transversal and longitudinal ionization cross sections are derived. We investigate the interaction of the superluminal radiation field with matter in atomic bound-bound and bound-free transitions. Estimates are given for Ly-{alpha} transitions effected by superluminal quanta in hydrogen-like ions. The tachyonic photoelectric effect is scrutinized, in the Born approximation and at the ionization threshold. The angular maxima occur at different scattering angles in the transversal and longitudinal cross sections, which can be used to sift out longitudinal tachyonic quanta in a photon flux. We calculate the tachyonic ionization and recombination cross sections for Rydberg states and study their asymptotic scaling with respect to the principal quantum number. At the ionization threshold of highly excited states of order n {approx} 10{sup 4}, the longitudinal cross section starts to compete with photoionization, in recombination even at lower levels.

Symmetric charge transfer cross section of uranium

International Nuclear Information System (INIS)

Shibata, Takemasa; Ogura, Koichi

1995-03-01

Symmetric charge transfer cross section of uranium was calculated under consideration of reaction paths. In the charge transfer reaction a d 3/2 electron in the U atom transfers into the d-electron site of U + ( 4 I 9/2 ) ion. The J value of the U atom produced after the reaction is 6, 5, 4 or 3, at impact energy below several tens eV, only resonant charge transfer in which the product atom is ground state (J=6) takes place. Therefore, the cross section is very small (4-5 x 10 -15 cm 2 ) compared with that considered so far. In the energy range of 100-1000eV the cross section increases with the impact energy because near resonant charge transfer in which an s-electron in the U atom transfers into the d-electron site of U + ion. Charge transfer cross section between U + in the first excited state (289 cm -1 ) and U in the ground state was also obtained. (author)

NNLO jet cross sections by subtraction

Energy Technology Data Exchange (ETDEWEB)

Somogyi, G.; Bolzoni, P. [DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Trocsanyi, Z. [CERN PH-TH, on leave from University of Debrecen and Institute of Nuclear Research of HAS, H-4001 P.O.Box 51 (Hungary)

2010-08-15

We report on the computation of a class of integrals that appear when integrating the so-called iterated singly-unresolved approximate cross section of the NNLO subtraction scheme of Refs. [G. Somogyi, Z. Trocsanyi, and V. Del Duca, JHEP 06, 024 (2005), (arXiv:hep-ph/0502226); G. Somogyi and Z. Trocsanyi, (2006), (arXiv:hep-ph/0609041); G. Somogyi, Z. Trocsanyi, and V. Del Duca, JHEP 01, 070 (2007), (arXiv:hep-ph/0609042); G. Somogyi and Z. Trocsanyi, JHEP 01, 052 (2007), (arXiv:hep-ph/0609043)] over the factorised phase space of unresolved partons. The integrated approximate cross section itself can be written as the product of an insertion operator (in colour space) times the Born cross section. We give selected results for the insertion operator for processes with two and three hard partons in the final state.

NNLO jet cross sections by subtraction

International Nuclear Information System (INIS)

Somogyi, G.; Bolzoni, P.; Trocsanyi, Z.

2010-01-01

We report on the computation of a class of integrals that appear when integrating the so-called iterated singly-unresolved approximate cross section of the NNLO subtraction scheme of Refs. [G. Somogyi, Z. Trocsanyi, and V. Del Duca, JHEP 06, 024 (2005), (arXiv:hep-ph/0502226); G. Somogyi and Z. Trocsanyi, (2006), (arXiv:hep-ph/0609041); G. Somogyi, Z. Trocsanyi, and V. Del Duca, JHEP 01, 070 (2007), (arXiv:hep-ph/0609042); G. Somogyi and Z. Trocsanyi, JHEP 01, 052 (2007), (arXiv:hep-ph/0609043)] over the factorised phase space of unresolved partons. The integrated approximate cross section itself can be written as the product of an insertion operator (in colour space) times the Born cross section. We give selected results for the insertion operator for processes with two and three hard partons in the final state.

FENDL/E. Evaluated nuclear data library of neutron nuclear interaction cross-sections and photon production cross-sections and photon-atom interaction cross sections for fusion applications. Version 1.1 of November 1994

International Nuclear Information System (INIS)

Pashchenko, A.B.; Wienke, H.; Ganesan, S.; McLaughlin, P.K.

1996-01-01

This document presents the description of a physical tape containing the basic evaluated nuclear data library of neutron nuclear interaction cross-sections and photon production cross-sections and photon-atom interaction cross-sections for fusion applications. It is part of FENDL, the evaluated nuclear data library for fusion applications. The nuclear data are available cost-free for distribution to interested scientists upon request. The data can also be retrieved by the user via online access through international computer networks. (author). 11 refs, 1 tab

Average cross sections for the 252Cf neutron spectrum

International Nuclear Information System (INIS)

Dezso, Z.; Csikai, J.

1977-01-01

A number of average cross sections have been measured for 252 Cf neutrons in (n, γ), (n,p), (n,2n), (n,α) reactions by the activation method and for fission by fission chamber. Cross sections have been determined for 19 elements and 45 reactions. The (n,γ) cross section values lie in the interval from 0.3 to 200 mb. The data as a function of target neutron number increases up to about N=60 with minimum near to dosed shells. The values lie between 0.3 mb and 113 mb. These cross sections decrease significantly with increasing the threshold energy. The values are below 20 mb. The data do not exceed 10 mb. Average (n,p) cross sections as a function of the threshold energy and average fission cross sections as a function of Zsup(4/3)/A are shown. The results obtained are summarized in tables

Vigorous convection as the explanation for Pluto's polygonal terrain.

Science.gov (United States)

Trowbridge, A J; Melosh, H J; Steckloff, J K; Freed, A M

2016-06-02

Pluto's surface is surprisingly young and geologically active. One of its youngest terrains is the near-equatorial region informally named Sputnik Planum, which is a topographic basin filled by nitrogen (N2) ice mixed with minor amounts of CH4 and CO ices. Nearly the entire surface of the region is divided into irregular polygons about 20-30 kilometres in diameter, whose centres rise tens of metres above their sides. The edges of this region exhibit bulk flow features without polygons. Both thermal contraction and convection have been proposed to explain this terrain, but polygons formed from thermal contraction (analogous to ice-wedges or mud-crack networks) of N2 are inconsistent with the observations on Pluto of non-brittle deformation within the N2-ice sheet. Here we report a parameterized convection model to compute the Rayleigh number of the N2 ice and show that it is vigorously convecting, making Rayleigh-Bénard convection the most likely explanation for these polygons. The diameter of Sputnik Planum's polygons and the dimensions of the 'floating mountains' (the hills of of water ice along the edges of the polygons) suggest that its N2 ice is about ten kilometres thick. The estimated convection velocity of 1.5 centimetres a year indicates a surface age of only around a million years.

Cross section library DOSCROS77 (in the SAND-II format)

International Nuclear Information System (INIS)

Zijp, W.L.; Nolthenius, H.J.; Borg, N.J.C.M. van der.

1977-08-01

The dosimetry cross section library DOSCROS77 is documented with tables, plots and cross section values averaged over a few reference spectra. This library is based on the ENDF/B-IV dosimetry file, supplemented with some other evaluations. The total number of reaction cross section sets incorporated in this library is 49 (+3 cover cross sections sets). The cross section data are available in a format which is suitable for the program SAND-II

Measured Hydrologic Storage Characteristics of Three Major Ice Wedge Polygon Types, Barrow, Alaska

Science.gov (United States)

Chamberlain, A. J.; Liljedahl, A.; Wilson, C. J.; Cable, W.; Romanovsky, V. E.

2014-12-01

Model simulations have suggested that the hydrologic fluxes and stores of Arctic wetlands are constrained by the micro-topographical features of ice wedge polygons, which are abundant in lowland tundra landscapes. Recently observed changes in ice wedge polygon landscapes - in particular, ice wedge degradation and trough formation - emphasize the need to better understand how differing ice wedge polygon morphologies affect the larger hydrologic system. Here we present three seasons of measured end-of-winter snow accumulation, continuous soil moisture and water table elevations, and repeated frost table mapping. Together, these describe the hydrologic characteristics of three main ice wedge polygon types: low centered polygons with limited trough development (representative of a ~500 year old vegetated drained thaw lake basin), and low- and high-centered polygons with well-defined troughs. Dramatic spatiotemporal variability exists both between polygon types and between the features of an individual polygon (e.g. troughs, centers, rims). Landscape-scale end-of-winter snow water equivalent is similar between polygon types, while the sub-polygon scale distribution of the surface water differs, both as snow and as ponded water. Some sub-polygon features appear buffered against large variations in water levels, while others display periods of prolonged recessions and large responses to rain events. Frost table elevations in general mimic the ground surface topography, but with spatiotemporal variability in thaw rate. The studied thaw seasons represented above long-term average rainfall, and in 2014, record high June precipitation. Differing ice wedge polygon types express dramatically different local hydrology, despite nearly identical climate forcing and landscape-scale snow accumulation, making ice wedge polygons an important component when describing the Arctic water, nutrient and energy system.

First measurement of the Rayleigh cross section

NARCIS (Netherlands)

Naus, H.; Ubachs, W.

2000-01-01

Rayleigh cross section for N2, Ar and SF6 was performed using the technique of cavity ring-down spectroscopy (CRDS). The experiment was based on the assumption that scattering cross section is equal to the extinction in the absence of absorption. The theory explains the molecular origin of

JSD1000: multi-group cross section sets for shielding materials

International Nuclear Information System (INIS)

Yamano, Naoki

1984-03-01

A multi-group cross section library for shielding safety analysis has been produced by using ENDF/B-IV. The library consists of ultra-fine group cross sections, fine-group cross sections, secondary gamma-ray production cross sections and effective macroscopic cross sections for typical shielding materials. Temperature dependent data at 300, 560 and 900 K have been also provided. Angular distributions of the group to group transfer cross section are defined by a new method of ''Direct Angular Representation'' (DAR) instead of the method of finite Legendre expansion. The library designated JSD1000 are stored in a direct access data base named DATA-POOL and data manipulations are available by using the DATA-POOL access package. The 3824 neutron group data of the ultra-fine group cross sections and the 100 neutron, 20 photon group cross sections are applicable to shielding safety analyses of nuclear facilities. This report provides detailed specifications and the access method for the JSD1000 library. (author)

Polygons on a rotating fluid surface.

Science.gov (United States)

Jansson, Thomas R N; Haspang, Martin P; Jensen, Kåre H; Hersen, Pascal; Bohr, Tomas

2006-05-05

We report a novel and spectacular instability of a fluid surface in a rotating system. In a flow driven by rotating the bottom plate of a partially filled, stationary cylindrical container, the shape of the free surface can spontaneously break the axial symmetry and assume the form of a polygon rotating rigidly with a speed different from that of the plate. With water, we have observed polygons with up to 6 corners. It has been known for many years that such flows are prone to symmetry breaking, but apparently the polygonal surface shapes have never been observed. The creation of rotating internal waves in a similar setup was observed for much lower rotation rates, where the free surface remains essentially flat [J. M. Lopez, J. Fluid Mech. 502, 99 (2004). We speculate that the instability is caused by the strong azimuthal shear due to the stationary walls and that it is triggered by minute wobbling of the rotating plate.

The Polygon

International Nuclear Information System (INIS)

2000-01-01

In Russian, ''The Polygon'' stands for a nuclear test site of 19.000 square kilometers in Kazakhstan, used by the former Soviet Union for hundreds of nuclear tests from 1947 to 1991. This film looks at the legacy of what was once a top secret area, now abandoned, but still sparsely populated, and at the work to be done to detect and map the areas of elevated radiation levels

Parameterized representation of macroscopic cross section for PWR reactor

International Nuclear Information System (INIS)

Fiel, João Cláudio Batista; Carvalho da Silva, Fernando; Senra Martinez, Aquilino; Leal, Luiz C.

2015-01-01

Highlights: • This work describes a parameterized representation of the homogenized macroscopic cross section for PWR reactor. • Parameterization enables a quick determination of problem-dependent cross-sections to be used in few group calculations. • This work allows generating group cross-section data to perform PWR core calculations without computer code calculations. - Abstract: The purpose of this work is to describe, by means of Chebyshev polynomials, a parameterized representation of the homogenized macroscopic cross section for PWR fuel element as a function of soluble boron concentration, moderator temperature, fuel temperature, moderator density and 235 92 U enrichment. The cross-section data analyzed are fission, scattering, total, transport, absorption and capture. The parameterization enables a quick and easy determination of problem-dependent cross-sections to be used in few group calculations. The methodology presented in this paper will allow generation of group cross-section data from stored polynomials to perform PWR core calculations without the need to generate them based on computer code calculations using standard steps. The results obtained by the proposed methodology when compared with results from the SCALE code calculations show very good agreement

The total collision cross section in the glory region

International Nuclear Information System (INIS)

Biesen, J.J.H. van den.

1982-01-01

Chapter 1 presents a calculation of approximate total cross sections in the glory region from noble gas potentials. The relations between the main features of the total cross section and the properties of the potential to which these are sensitive are extensively investigated in chapter II. A beam apparatus has been developed, which allows for accurate measurements on the total cross section. All effects due to the finite angular and velocity resolution of the apparatus can be eliminated from the data to yield actual total cross sections as a function of the relative velocity. This facilitates a comparison to total cross sections predicted by potentials available in the literature. A brief description of the apparatus and of the data reduction is given in chapter III. The total cross section data obtained for various noble gas combinations are presented and analysed in chapter IV, where also a large number of potentials proposed in the literature is tested. In chapter V the quenching of the glories in the case of a non-spherical interaction is analysed. Subsequently, total cross section data for some atom-molecule systems are discussed. (Auth.)

Hardon cross sections at ultra high energies

International Nuclear Information System (INIS)

Yodh, G.B.

1987-01-01

A review of results on total hadronic cross sections at ultra high energies obtained from a study of longitudinal development of cosmic ray air showers is given. The experimental observations show that proton-air inelastic cross section increases from 275 mb to over 500 mb as the collision energy in the center of mass increases from 20 GeV to 20 TeV. The proton-air inelastic cross section, obtained from cosmic ray data at √s = 30 TeV, is compared with calculations using various different models for the energy variation of the parameters of the elementary proton-proton interaction. Three conclusions are derived

Total cross section results for deuterium electrodisintegration

International Nuclear Information System (INIS)

Skopik, D.M.; Murphy, J.J. II; Shin, Y.M.

1976-01-01

Theoretical total cross sections for deuterium electrodisintegration are presented as a function of incident electron energy. The cross section has been calculated using virtual photon theory with Partovi's photodisintegration calculation for E/subx/ > 10 MeV and effective range theory for E/subx/ 2 H(e, n) reaction in Tokamak reactors

Electron-impact ionization cross section of rubidium

International Nuclear Information System (INIS)

Kim, Y.; Migdalek, J.; Siegel, W.; Bieron, J.

1998-01-01

A theoretical model for electron-impact ionization cross section has been applied to Rb and the theoretical cross section (from the threshold to 1 keV in incident energy) is in good agreement with the recent experimental data obtained using Rb atoms trapped in a magneto-optical trap. The theoretical model, called the binary-encounter endash dipole (BED) model, combines a modified Mott cross section with the high-energy behavior of Born cross sections. To obtain the continuum dipole oscillator strength df/dE of the 5s electron required in the BED model, we used Dirac-Fock continuum wave functions with a core polarization potential that reproduced the known position of the Cooper minimum in the photoionization cross section. For inner-shell ionization, we used a simpler version of df/dE, which retained the hydrogenic shape. The contributions of the 4p→4d, 5s, and 5p autoionizing excitations were estimated using the plane-wave Born approximation. As a by-product, we also present the dipole oscillator strengths for the 5s→np 1/2 and 5s→np 3/2 transitions for high principal quantum numbers n near the ionization threshold obtained from the Dirac-Fock wave functions with the same core polarization potential as that used for the continuum wave functions. copyright 1998 The American Physical Society

Measurement cross sections for radioisotopes production

International Nuclear Information System (INIS)

Garrido, E.

2011-01-01

New radioactive isotopes for nuclear medicine can be produced using particle accelerators. This is one goal of Arronax, a high energy - 70 MeV - high intensity - 2*350 μA - cyclotron set up in Nantes. A priority list was established containing β - - 47 Sc, 67 Cu - β + - 44 Sc, 64 Cu, 82 Sr/ 82 Rb, 68 Ge/ 68 Ga - and α emitters - 211 At. Among these radioisotopes, the Scandium 47 and the Copper 67 have a strong interest in targeted therapy. The optimization of their productions required a good knowledge of their cross-sections but also of all the contaminants created during irradiation. We launched on Arronax a program to measure these production cross-sections using the Stacked-Foils' technique. It consists in irradiating several groups of foils - target, monitor and degrader foils - and in measuring the produced isotopes by γ-spectrometry. The monitor - nat Cu or nat Ni - is used to correct beam loss whereas degrader foils are used to lower beam energy. We chose to study the nat Ti(p,X) 47 Sc and 68 Zn(p,2p) 67 Cu reactions. Targets are respectively natural Titanium foil - bought from Goodfellow - and enriched Zinc 68 deposited on Silver. In the latter case, Zn targets were prepared in-house - electroplating of 68 Zn - and a chemical separation between Copper and Gallium isotopes has to be made before γ counting. Cross-section values for more than 40 different reactions cross-sections have been obtained from 18 MeV to 68 MeV. A comparison with the Talys code is systematically done. Several parameters of theoretical models have been studied and we found that is not possible to reproduce faithfully all the cross-sections with a given set of parameters. (author)

Neutron cross section libraries for analysis of fusion neutronics experiments

International Nuclear Information System (INIS)

Kosako, Kazuaki; Oyama, Yukio; Maekawa, Hiroshi; Nakamura, Tomoo

1988-03-01

We have prepared two computer code systems producing neutron cross section libraries to analyse fusion neutronics experiments. First system produces the neutron cross section library in ANISN format, i.e., the multi-group constants in group independent format. This library can be obtained by using the multi-group constant processing code system MACS-N and the ANISN format cross section compiling code CROKAS. Second system is for the continuous energy cross section library for the MCNP code. This library can be obtained by the nuclear data processing system NJOY which generates pointwise energy cross sections and the cross section compiling code MACROS for the MCNP library. In this report, we describe the production procedures for both types of the cross section libraries, and show six libraries with different conditions in ANISN format and a library for the MCNP code. (author)

Temperature-dependent absorption cross sections for hydrogen peroxide vapor

Science.gov (United States)

Nicovich, J. M.; Wine, P. H.

1988-01-01

Relative absorption cross sections for hydrogen peroxide vapor were measured over the temperature ranges 285-381 K for lambda = 230 nm-295 nm and 300-381 K for lambda = 193 nm-350 nm. The well established 298 K cross sections at 202.6 and 228.8 nm were used as an absolute calibration. A significant temperature dependence was observed at the important tropospheric photolysis wavelengths lambda over 300 nm. Measured cross sections were extrapolated to lower temperatures, using a simple model which attributes the observed temperature dependence to enhanced absorption by molecules possessing one quantum of O-O stretch vibrational excitation. Upper tropospheric photodissociation rates calculated using the extrapolated cross sections are about 25 percent lower than those calculated using currently recommended 298 K cross sections.

A Laplace type problem for regular lattices with circular section obstacles

Directory of Open Access Journals (Sweden)

D. Barilla

2013-12-01

Full Text Available In this paper, we compute the probability that a segment of random position and of constant length intersects a side of a regular lattice with circular sections obstacles. In particular, we obtain the formula of a probability already computed by Caristi and Stoka, as well as the formula of the Laplace probability. The results can be used for possible applications in economy and engineering, in particular for transportation problems.

Does regular practice of physical activity reduce the risk of dysphonia?

Science.gov (United States)

Assunção, Ada Avila; de Medeiros, Adriane Mesquita; Barreto, Sandhi Maria; Gama, Ana Cristina Cortes

2009-12-01

The purpose of this study was to investigate the association between regular physical activity and the prevalence of dysphonia. A cross-sectional study was conducted with 3142 teachers from 129 municipal public schools in the city of Belo Horizonte, Brazil. The dependent variable, dysphonia, was classified (absent or present) according to reported symptoms (fatigue when speaking and loss of voice quality), their frequency (occasionally and daily), and duration (past 15 days). The independent variable was regular physical activity. The degree of association was estimated based on the prevalence ratio and a 95% confidence interval obtained by the Poisson regression adapted for cross-sectional studies. In the study sample, the prevalence of dysphonia in teachers was 15.63%. Nearly half (47.52%) of the teachers reported no regular practice of physical exercises. The remaining teachers (52.48%) walked and did physical exercises, sports, and other activities; 31.25% undertook these activities once or twice a week, and 21.23% exercised three or more times a week. Teachers who did not practice physical activity were more likely to present dysphonia compared to those that exercised three or more times a week. Regular physical activity was associated positively with the prevalence of dysphonia.

Calculation of the intermediate energy activation cross section

Energy Technology Data Exchange (ETDEWEB)

Furihata, Shiori; Yoshizawa, Nobuaki [Mitsubishi Research Inst., Inc., Tokyo (Japan)

1997-03-01

We discussed the activation cross section in order to predict accurately the activation of soil around an accelerator with high energy and strong intensity beam. For the assessment of the accuracy of activation cross sections estimated by a numerical model, we compared the calculated cross section with various experimental data, for Si(p,x){sup 22}Na, Al(p,x){sup 22}Na, Fe(p,x){sup 22}Na, Si(p,x){sup 7}Be, O(p,x){sup 3}H, Al(p,x){sup 3}H and Si(p,x){sup 3}H reactions. We used three computational codes, i.e., quantum molecular dynamics (QMD) plus statistical decay model (SDM), HETC-3STEP and the semiempirical method developed by Silberberg et.al. It is observed that the codes are accurate above 1GeV, except for {sup 7}Be production. We also discussed the difference between the activation cross sections of proton- and neutron-induced reaction. For the incident energy at 40MeV, it is found that {sup 3}H production cross sections of neutron-induced reaction are ten times as large as those of proton-induced reaction. It is also observed that the choice of the activation cross sections seriously affects to the estimate of saturated radioactivity, if the maximum energy of neutron flux is below 100MeV. (author)

Validation of evaluated neutron standard cross sections

International Nuclear Information System (INIS)

Badikov, S.; Golashvili, T.

2008-01-01

Some steps of the validation and verification of the new version of the evaluated neutron standard cross sections were carried out. In particular: -) the evaluated covariance data was checked for physical consistency, -) energy-dependent evaluated cross-sections were tested in most important neutron benchmark field - 252 Cf spontaneous fission neutron field, -) a procedure of folding differential standard neutron data in group representation for preparation of specialized libraries of the neutron standards was verified. The results of the validation and verification of the neutron standards can be summarized as follows: a) the covariance data of the evaluated neutron standards is physically consistent since all the covariance matrices of the evaluated cross sections are positive definite, b) the 252 Cf spectrum averaged standard cross-sections are in agreement with the evaluated integral data (except for 197 Au(n,γ) reaction), c) a procedure of folding differential standard neutron data in group representation was tested, as a result a specialized library of neutron standards in the ABBN 28-group structure was prepared for use in reactor applications. (authors)

A Polygon and Point-Based Approach to Matching Geospatial Features

Directory of Open Access Journals (Sweden)

Juan J. Ruiz-Lendínez

2017-12-01

Full Text Available A methodology for matching bidimensional entities is presented in this paper. The matching is proposed for both area and point features extracted from geographical databases. The procedure used to obtain homologous entities is achieved in a two-step process: The first matching, polygon to polygon matching (inter-element matching, is obtained by means of a genetic algorithm that allows the classifying of area features from two geographical databases. After this, we apply a point to point matching (intra-element matching based on the comparison of changes in their turning functions. This study shows that genetic algorithms are suitable for matching polygon features even if these features are quite different. Our results show up to 40% of matched polygons with differences in geometrical attributes. With regards to point matching, the vertex from homologous polygons, the function and threshold values proposed in this paper show a useful method for obtaining precise vertex matching.

View-CXS neutron and photon cross-sections viewer

International Nuclear Information System (INIS)

Subbaiah, K.V.; Sunil Sunny, C.

2004-01-01

A graphical user-friendly interface is developed in Visual Basic (VB)-6 to view the variation of neutron and photon interaction cross-sections of different isotopes as a function of energy. VB subroutines developed read the binary data files of cross-sections created in MCNP-ACE (Briesmeister, J.F., 1993. MCNP - a general purpose Monte Carlo N-Particle Transport code. Version 4A. LANL, USA), ANISN-DLC (Engle W.W. Jr., 1967, A User's Manual for ANISN, K-1693; ORNL, 1974. 100 group neutron cross section data based on ENDF/B-III. Oak Ridge National Laboratory, USA) and KENO-AMPX (Petrie, L.M., Landers, N.F., 1984 KENO-Va- An Improved Monte Carlo Criticality Program with Super Grouping. RSICC-CCC-548, USA) formats using LAHEY-77 Fortran Compiler. The information on isotopes present in each library will be displayed with the help of database files prepared using Micro-Soft ACESS. The cross-section data can be viewed in different presentation styles namely, line graphs, bar graphs, histograms etc., with different color and symbol options. The cross-section plots generated can be saved as Bit-Map file to embed in any other text files. This software enables inter comparison of cross-sections from different type of libraries for isotopes as well as mixtures. Provision is made to view the cross-sections for nuclear reactions such as (n,γ), (n,f), (n,α), etc. The software can be obtained from Radiation Safety Information and Computational Centre (RSICC), ORNL, USA with the code package identification number PSR-514. The software package needs a hard disk space of about 80 MB when installed and works in WINDOWS-95/98/2000 operating systems

Optical Model and Cross Section Uncertainties

Energy Technology Data Exchange (ETDEWEB)

Herman,M.W.; Pigni, M.T.; Dietrich, F.S.; Oblozinsky, P.

2009-10-05

Distinct minima and maxima in the neutron total cross section uncertainties were observed in model calculations using spherical optical potential. We found this oscillating structure to be a general feature of quantum mechanical wave scattering. Specifically, we analyzed neutron interaction with 56Fe from 1 keV up to 65 MeV, and investigated physical origin of the minima.We discuss their potential importance for practical applications as well as the implications for the uncertainties in total and absorption cross sections.

Pion-nucleus cross sections

International Nuclear Information System (INIS)

Barashenkov, V.S.

1990-01-01

The tables of inelastic and total cross sections of π ± mesons interactions with nuclei 4 He- 238 U are presented. The tables are obtained by theoretical analysis of known experimental data for energies higher some tens of MeV. 1 ref.; 1 tab

Proton-air and proton-proton cross sections

Directory of Open Access Journals (Sweden)

Ulrich Ralf

2013-06-01

Full Text Available Different attempts to measure hadronic cross sections with cosmic ray data are reviewed. The major results are compared to each other and the differences in the corresponding analyses are discussed. Besides some important differences, it is crucial to see that all analyses are based on the same fundamental relation of longitudinal air shower development to the observed fluctuation of experimental observables. Furthermore, the relation of the measured proton-air to the more fundamental proton-proton cross section is discussed. The current global picture combines hadronic proton-proton cross section data from accelerator and cosmic ray measurements and indicates a good consistency with predictions of models up to the highest energies.

Fission-neutron displacement cross sections in metals

International Nuclear Information System (INIS)

Takamura, Saburo; Aruga, Takeo; Nakata, Kiyotomo

1985-01-01

The sensitivity damage rates for 22 metals were measured after fission-spectrum neutron irradiation at low temperature and the experimental damage rates were compared with the theoretical calculation. The relation between the theoretical displacement cross section and the atomic weight of metals can be written by two curves; one is for fcc and hcp metals, and another is for bcc metals. On the other hand, the experimental displacement cross section versus atomic weight is shown approximately by a curve for both fcc and bcc metals, and the cross section for hcp metals deviates from the curve. The defect production efficiency is 0.3-0.4 for fcc metals and 0.6-0.8 for bcc metals. (orig.)

A numerical investigation of sub-wavelength resonances in polygonal metamaterial cylinders

DEFF Research Database (Denmark)

Arslanagic, Samel; Breinbjerg, Olav

2009-01-01

The sub-wavelength resonances, known to exist in metamaterial radiators and scatterers of circular cylindrical shape, are investigated with the aim of determining if these resonances also exist for polygonal cylinders and, if so, how they are affected by the shape of the polygon. To this end, a set...... of polygonal cylinders excited by a nearby electric line current is analyzed numerically and it is shown, through detailed analysis of the near-field distribution and radiation resistance, that these polygonal cylinders do indeed support sub-wavelength resonances similar to those of the circular cylinders...

Compact fitting formulas for electron-impact cross sections

International Nuclear Information System (INIS)

Kim, Y.K.

1992-01-01

Compact fitting formulas, which contain four fitting constants, are presented for electron-impact excitation and ionization cross sections of atoms and ions. These formulas can fit experimental and theoretical cross sections remarkably well, when resonant structures are smoothed out, from threshold to high incident electron energies (<10 keV), beyond which relativistic formulas are more appropriate. Examples of fitted cross sections for some atoms and ions are presented. The basic form of the formula is valid for both atoms and molecules

Single-level resonance parameters fit nuclear cross-sections

Science.gov (United States)

Drawbaugh, D. W.; Gibson, G.; Miller, M.; Page, S. L.

1970-01-01

Least squares analyses of experimental differential cross-section data for the U-235 nucleus have yielded single level Breit-Wigner resonance parameters that fit, simultaneously, three nuclear cross sections of capture, fission, and total.

Supramolecule-to-supramolecule transformations of coordination-driven self-assembled polygons.

Science.gov (United States)

Zhao, Liang; Northrop, Brian H; Stang, Peter J

2008-09-10

Two types of supramolecular transformations, wherein a self-assembled Pt(II)-pyridyl metal-organic polygon is controllably converted into an alternative polygon, have been achieved through the reaction between cobalt carbonyl and the acetylene moiety of a dipyridyl donor ligand. A [6 + 6] hexagon is transformed into two [3 + 3] hexagons, and a triangle-square mixture is converted into [2 + 2] rhomboids. 1H and 31P NMR spectra are used to track the transformation process and evaluate the yield of new self-assembled polygons. Such transformed species are identified by electrospray ionization (ESI) mass spectrometry. This new kind of supramolecule-to-supramolecule transformations provides a viable means for constructing, and then converting, new self-assembled polygons.

Total cross section of highly excited strings

International Nuclear Information System (INIS)

Lizzi, F.; Senda, I.

1990-01-01

The unpolarized total cross section for the joining of two highly excited strings is calculated. The calculation is performed by taking the average overall states in the given excitation levels of the initial strings. We find that the total cross section grows with the energy and momentum of the initial states. (author). 8 refs, 1 fig

MXS cross-section preprocessor user's manual

International Nuclear Information System (INIS)

Parker, F.; Ishikawa, M.; Luck, L.

1987-03-01

The MXS preprocessor has been designed to reduce the execution time of programs using isotopic cross-section data and to both reduce the execution time and improve the accuracy of shielding-factor interpolation in the SIMMER-II accident analysis program. MXS is a dual-purpose preprocessing code to: (1) mix isotopes into materials and (2) fit analytic functions to the shelf-shielding data. The program uses the isotope microscopic neutron cross-section data from the CCCC standard interface file ISOTXS and the isotope Bondarenko self-shielding data from the CCCC standard interface file BRKOXS to generate cross-section and self-shielding data for materials. The materials may be a mixture of several isotopes. The self-shielding data for the materials may be the actual shielding factors or a set of coefficients for functions representing the background dependence of the shielding factors. A set of additional data is given to describe the functions necessary to interpolate the shielding factors over temperature

Neutron capture cross sections of Kr

Directory of Open Access Journals (Sweden)

Fiebiger Stefan

2017-01-01

Full Text Available Neutron capture and β− -decay are competing branches of the s-process nucleosynthesis path at 85Kr [1], which makes it an important branching point. The knowledge of its neutron capture cross section is therefore essential to constrain stellar models of nucleosynthesis. Despite its importance for different fields, no direct measurement of the cross section of 85Kr in the keV-regime has been performed. The currently reported uncertainties are still in the order of 50% [2, 3]. Neutron capture cross section measurements on a 4% enriched 85Kr gas enclosed in a stainless steel cylinder were performed at Los Alamos National Laboratory (LANL using the Detector for Advanced Neutron Capture Experiments (DANCE. 85Kr is radioactive isotope with a half life of 10.8 years. As this was a low-enrichment sample, the main contaminants, the stable krypton isotopes 83Kr and 86Kr, were also investigated. The material was highly enriched and contained in pressurized stainless steel spheres.

NNLO jet cross sections by subtraction

Science.gov (United States)

Somogyi, G.; Bolzoni, P.; Trócsányi, Z.

2010-08-01

We report on the computation of a class of integrals that appear when integrating the so-called iterated singly-unresolved approximate cross section of the NNLO subtraction scheme of Refs. [G. Somogyi, Z. Trócsányi, and V. Del Duca, JHEP 06, 024 (2005), arXiv:hep-ph/0502226; G. Somogyi and Z. Trócsányi, (2006), arXiv:hep-ph/0609041; G. Somogyi, Z. Trócsányi, and V. Del Duca, JHEP 01, 070 (2007), arXiv:hep-ph/0609042; G. Somogyi and Z. Trócsányi, JHEP 01, 052 (2007), arXiv:hep-ph/0609043] over the factorised phase space of unresolved partons. The integrated approximate cross section itself can be written as the product of an insertion operator (in colour space) times the Born cross section. We give selected results for the insertion operator for processes with two and three hard partons in the final state.

Polygons and adhesion plaques and the disassembly and assembly of myofibrils in cardiac myocytes.

Science.gov (United States)

Lin, Z X; Holtzer, S; Schultheiss, T; Murray, J; Masaki, T; Fischman, D A; Holtzer, H

1989-06-01

Successive stages in the disassembly of myofibrils and the subsequent assembly of new myofibrils have been studied in cultures of dissociated chick cardiac myocytes. The myofibrils in trypsinized and dispersed myocytes are sequentially disassembled during the first 3 d of culture. They split longitudinally and then assemble into transitory polygons. Multiples of single sarcomeres, the cardiac polygons, are analogous to the transitory polygonal configurations assumed by stress fibers in spreading fibroblasts. They differ from their counterparts in fibroblasts in that they consist of muscle alpha-actinin vertices and muscle myosin heavy chain struts, rather than of the nonmuscle contractile protein isoforms of stress fiber polygons. EM sections reveal the vertices and struts in cardiac polygons to be typical Z and A bands. Most cardiac polygons are eliminated by day 5 of culture. Concurrent with the disassembly and elimination of the original myofibrils new myofibrils are rapidly assembled elsewhere in the same myocyte. Without exception both distal tips of each nascent myofibril terminate in adhesion plaques. The morphology and composition of the adhesion plaques capping each end of each myofibril are similar to those of the termini of stress fibers in fibroblasts. However, whereas the adhesion complexes involving stress fibers in fibroblasts consist of vinculin/nonmuscle alpha-actinin/beta- and gamma-actins, the analogous structures in myocytes involving myofibrils consist of vinculin/muscle alpha-actinin/alpha-actin. The addition of 1.7-2.0 microns sarcomeres to the distal tips of an elongating myofibril, irrespective of whether the myofibril consists of 1, 10, or several hundred tandem sarcomeres, occurs while the myofibril appears to remain linked to its respective adhesion plaques. The adhesion plaques in vitro are the equivalent of the in vivo intercalated discs, both in terms of their molecular composition and with respect to their functioning as initiating

PolyFit: Polygonal Surface Reconstruction from Point Clouds

KAUST Repository

Nan, Liangliang; Wonka, Peter

2017-01-01

We propose a novel framework for reconstructing lightweight polygonal surfaces from point clouds. Unlike traditional methods that focus on either extracting good geometric primitives or obtaining proper arrangements of primitives, the emphasis of this work lies in intersecting the primitives (planes only) and seeking for an appropriate combination of them to obtain a manifold polygonal surface model without boundary.,We show that reconstruction from point clouds can be cast as a binary labeling problem. Our method is based on a hypothesizing and selection strategy. We first generate a reasonably large set of face candidates by intersecting the extracted planar primitives. Then an optimal subset of the candidate faces is selected through optimization. Our optimization is based on a binary linear programming formulation under hard constraints that enforce the final polygonal surface model to be manifold and watertight. Experiments on point clouds from various sources demonstrate that our method can generate lightweight polygonal surface models of arbitrary piecewise planar objects. Besides, our method is capable of recovering sharp features and is robust to noise, outliers, and missing data.

PolyFit: Polygonal Surface Reconstruction from Point Clouds

KAUST Repository

Nan, Liangliang

2017-12-25

We propose a novel framework for reconstructing lightweight polygonal surfaces from point clouds. Unlike traditional methods that focus on either extracting good geometric primitives or obtaining proper arrangements of primitives, the emphasis of this work lies in intersecting the primitives (planes only) and seeking for an appropriate combination of them to obtain a manifold polygonal surface model without boundary.,We show that reconstruction from point clouds can be cast as a binary labeling problem. Our method is based on a hypothesizing and selection strategy. We first generate a reasonably large set of face candidates by intersecting the extracted planar primitives. Then an optimal subset of the candidate faces is selected through optimization. Our optimization is based on a binary linear programming formulation under hard constraints that enforce the final polygonal surface model to be manifold and watertight. Experiments on point clouds from various sources demonstrate that our method can generate lightweight polygonal surface models of arbitrary piecewise planar objects. Besides, our method is capable of recovering sharp features and is robust to noise, outliers, and missing data.

Depression among the urban poor in Peninsular Malaysia: a community based cross-sectional study.

Science.gov (United States)

Tan, Kok Leong; Yadav, Hematram

2013-01-01

This community based cross-sectional study examined the prevalence and factors associated with depression among urban poor in Peninsular Malaysia. The Patient Health Questionnaire (PHQ-9) was used to determine the presence or absence of depression. The prevalence of depression among the urban poor was 12.3%. Factors significantly associated with depression included respondents under 25 years old, male gender, living in the area for less than four years and those who do not exercise regularly. It is important to identify individuals with depression and its associated factors early because depression can severely affect the quality of life.

Mid-IR Absorption Cross-Section Measurements of Hydrocarbons

KAUST Repository

Alrefae, Majed Abdullah

2013-01-01

-known at combustion-relevant conditions. Absorption cross-section is an important spectroscopic quantity and has direct relation to the species concentration. In this work, the absorption cross-sections of basic hydrocarbons are measured using Fourier Transform

LHCb cross-section measurements with heavy flavour jets

CERN Multimedia

Michielin, Emanuele

2017-01-01

Cross-section measurements of jets originating from the hadronization of beauty ($b$) and charm ($c$) quarks at LHCb give the unique opportunity to probe Parton Distribution Functions (PDFs) at low and large momentum fraction and to test the Standard Model in the forward region. In this poster the production of $t\\bar{t}$ pairs in the forward region, the measurement of the $W+b\\bar{b}$ and $W+c\\bar{c}$ cross-section and the measurement of the $Z\\rightarrow b\\bar{b}$ cross-section are presented.

Anisotropic rectangular metric for polygonal surface remeshing

KAUST Repository

Pellenard, Bertrand

2013-06-18

We propose a new method for anisotropic polygonal surface remeshing. Our algorithm takes as input a surface triangle mesh. An anisotropic rectangular metric, defined at each triangle facet of the input mesh, is derived from both a user-specified normal-based tolerance error and the requirement to favor rectangle-shaped polygons. Our algorithm uses a greedy optimization procedure that adds, deletes and relocates generators so as to match two criteria related to partitioning and conformity.

Anisotropic rectangular metric for polygonal surface remeshing

KAUST Repository

Pellenard, Bertrand; Morvan, Jean-Marie; Alliez, Pierre

2013-01-01

We propose a new method for anisotropic polygonal surface remeshing. Our algorithm takes as input a surface triangle mesh. An anisotropic rectangular metric, defined at each triangle facet of the input mesh, is derived from both a user-specified normal-based tolerance error and the requirement to favor rectangle-shaped polygons. Our algorithm uses a greedy optimization procedure that adds, deletes and relocates generators so as to match two criteria related to partitioning and conformity.

Polygons, Stars, and Clusters; an Investigation of Polygon Displays

Science.gov (United States)

1988-01-01

variables were chosen, nine in each case , to give reasonably complex polygons without being too complex. I have seen no reported studies of the relation...Pont. Catalina C Datsun 210, Toyota Corolla, Dodge Colt, Honda Civic, Mazda GLC, Subaru, Ford Fiesta, Plym. Champ Figure 6. Clusters on the basis of...Merc. Marquis, Pont. Catalina, Pont. Grand Prix C Datsun 210, Toyota Corolla, Dodge Colt, Honda Civic, Mazda GLC, Subaru, Ford Fiesta, Plym. Champ

Neutron cross section measurements for the Fast Breeder Program

International Nuclear Information System (INIS)

Block, R.C.

1979-06-01

This research was concerned with the measurement of neutron cross sections of importance to the Fast Breeder Reactor. The capture and total cross sections of fission products ( 101 102 104 Ru, 143 145 Nd, 149 Sm, 95 97 Mo, Cs, Pr, Pd, 107 Pd, 99 Tc) and tag gases (Kr, 78 80 Kr) were measured up to 100 keV. Filtered neutron beams were used to measure the capture cross section of 238 U (with an Fe filter) and the total cross section of Na (with a Na filter). A radioactive neutron capture detector was developed. A list of publications is included

Developing Scientific Reasoning Through Drawing Cross-Sections

Science.gov (United States)

Hannula, K. A.

2012-12-01

Cross-sections and 3D models of subsurface geology are typically based on incomplete information (whether surface geologic mapping, well logs, or geophysical data). Creating and evaluating those models requires spatial and quantitative thinking skills (including penetrative thinking, understanding of horizontality, mental rotation and animation, and scaling). However, evaluating the reasonableness of a cross-section or 3D structural model also requires consideration of multiple possible geometries and geologic histories. Teaching students to create good models requires application of the scientific methods of the geosciences (such as evaluation of multiple hypotheses and combining evidence from multiple techniques). Teaching these critical thinking skills, especially combined with teaching spatial thinking skills, is challenging. My Structural Geology and Advanced Structural Geology courses have taken two different approaches to developing both the abilities to visualize and to test multiple models. In the final project in Structural Geology (a 3rd year course with a pre-requisite sophomore mapping course), students create a viable cross-section across part of the Wyoming thrust belt by hand, based on a published 1:62,500 geologic map. The cross-section must meet a number of geometric criteria (such as the template constraint), but is not required to balance. Each student tries many potential geometries while trying to find a viable solution. In most cases, the students don't visualize the implications of the geometries that they try, but have to draw them and then erase their work if it does not meet the criteria for validity. The Advanced Structural Geology course used Midland Valley's Move suite to test the cross-sections that they made in Structural Geology, mostly using the flexural slip unfolding algorithm and testing whether the resulting line lengths balanced. In both exercises, students seemed more confident in the quality of their cross-sections when the

Applications of the BEam Cross section Analysis Software (BECAS)

DEFF Research Database (Denmark)

Blasques, José Pedro Albergaria Amaral; Bitsche, Robert; Fedorov, Vladimir

2013-01-01

A newly developed framework is presented for structural design and analysis of long slender beam-like structures, e.g., wind turbine blades. The framework is based on the BEam Cross section Analysis Software – BECAS – a finite element based cross section analysis tool. BECAS is used for the gener......A newly developed framework is presented for structural design and analysis of long slender beam-like structures, e.g., wind turbine blades. The framework is based on the BEam Cross section Analysis Software – BECAS – a finite element based cross section analysis tool. BECAS is used...... for the generation of beam finite element models which correctly account for effects stemming from material anisotropy and inhomogeneity in cross sections of arbitrary geometry. These type of modelling approach allows for an accurate yet computationally inexpensive representation of a general class of three...

Absolute photoionization cross-section of the methyl radical.

Science.gov (United States)

Taatjes, Craig A; Osborn, David L; Selby, Talitha M; Meloni, Giovanni; Fan, Haiyan; Pratt, Stephen T

2008-10-02

The absolute photoionization cross-section of the methyl radical has been measured using two completely independent methods. The CH3 photoionization cross-section was determined relative to that of acetone and methyl vinyl ketone at photon energies of 10.2 and 11.0 eV by using a pulsed laser-photolysis/time-resolved synchrotron photoionization mass spectrometry method. The time-resolved depletion of the acetone or methyl vinyl ketone precursor and the production of methyl radicals following 193 nm photolysis are monitored simultaneously by using time-resolved synchrotron photoionization mass spectrometry. Comparison of the initial methyl signal with the decrease in precursor signal, in combination with previously measured absolute photoionization cross-sections of the precursors, yields the absolute photoionization cross-section of the methyl radical; sigma(CH3)(10.2 eV) = (5.7 +/- 0.9) x 10(-18) cm(2) and sigma(CH3)(11.0 eV) = (6.0 +/- 2.0) x 10(-18) cm(2). The photoionization cross-section for vinyl radical determined by photolysis of methyl vinyl ketone is in good agreement with previous measurements. The methyl radical photoionization cross-section was also independently measured relative to that of the iodine atom by comparison of ionization signals from CH3 and I fragments following 266 nm photolysis of methyl iodide in a molecular-beam ion-imaging apparatus. These measurements gave a cross-section of (5.4 +/- 2.0) x 10(-18) cm(2) at 10.460 eV, (5.5 +/- 2.0) x 10(-18) cm(2) at 10.466 eV, and (4.9 +/- 2.0) x 10(-18) cm(2) at 10.471 eV. The measurements allow relative photoionization efficiency spectra of methyl radical to be placed on an absolute scale and will facilitate quantitative measurements of methyl concentrations by photoionization mass spectrometry.

Cross-section crushing behaviour of hat-sections (Part II: Analytical modelling)

NARCIS (Netherlands)

Hofmeyer, H.

2005-01-01

Hat-sections are often used to experimentally investigate building sheeting subject to a concentrated load and bending. In car doors, hat-sections are used for side-impact protection. Their crushing behaviour can partly be explained by only observing their cross-sectional behaviour [1]. This

Asymptotic behaviour of pion-pion total cross-sections

Energy Technology Data Exchange (ETDEWEB)

Greynat, David [Dipartimento di Scienze Fisiche, Universita di Napoli “Federico II”,Via Cintia, 80126 Napoli (Italy); Rafael, Eduardo de [Aix-Marseille Université, CNRS,CPT, UMR 7332, 13288 Marseille (France); Université de Toulon, CNRS,CPT, UMR 7332, 83957 La Garde (France); Vulvert, Grégory [Departament de Física Teórica, IFIC,CSIC - Universitat de València, Apt. Correus 22085, E-46071 València (Spain)

2014-03-24

We derive a sum rule which shows that the Froissart-Martin bound for the asymptotic behaviour of the ππ total cross sections at high energies, if modulated by the Lukaszuk-Martin coefficient of the leading log{sup 2} s behaviour, cannot be an optimal bound in QCD. We next compute the total cross sections for π{sup +}π{sup −}, π{sup ±}π{sup 0} and π{sup 0}π{sup 0} scattering within the framework of the constituent chiral quark model (CχQM) in the limit of a large number of colours N{sub c} and discuss their asymptotic behaviours. The same ππ cross sections are also discussed within the general framework of Large-N{sub c} QCD and we show that it is possible to make an Ansatz for the isospin I=1 and I=0 spectrum which satisfy the Froissart-Martin bound with coefficients which, contrary to the Lukaszuk-Martin coefficient, are not singular in the chiral limit and have the correct Large-N{sub c} counting. We finally propose a simple phenomenological model which matches the low energy behaviours of the σ{sub π{sup ±}π{sup 0total}}(s) cross section predicted by the CχQM with the high energy behaviour predicted by the Large-N{sub c} Ansatz. The magnitude of these cross sections at very high energies is of the order of those observed for the pp and pp-bar scattering total cross sections.

Asymptotic behaviour of pion-pion total cross-sections

International Nuclear Information System (INIS)

Greynat, David; Rafael, Eduardo de; Vulvert, Grégory

2014-01-01

We derive a sum rule which shows that the Froissart-Martin bound for the asymptotic behaviour of the ππ total cross sections at high energies, if modulated by the Lukaszuk-Martin coefficient of the leading log 2  s behaviour, cannot be an optimal bound in QCD. We next compute the total cross sections for π + π − , π ± π 0 and π 0 π 0 scattering within the framework of the constituent chiral quark model (CχQM) in the limit of a large number of colours N c and discuss their asymptotic behaviours. The same ππ cross sections are also discussed within the general framework of Large-N c QCD and we show that it is possible to make an Ansatz for the isospin I=1 and I=0 spectrum which satisfy the Froissart-Martin bound with coefficients which, contrary to the Lukaszuk-Martin coefficient, are not singular in the chiral limit and have the correct Large-N c counting. We finally propose a simple phenomenological model which matches the low energy behaviours of the σ π ± π 0 total (s) cross section predicted by the CχQM with the high energy behaviour predicted by the Large-N c Ansatz. The magnitude of these cross sections at very high energies is of the order of those observed for the pp and pp-bar scattering total cross sections

Clastic polygonal networks around Lyot crater, Mars: Possible formation mechanisms from morphometric analysis

Science.gov (United States)

Brooker, L. M.; Balme, M. R.; Conway, S. J.; Hagermann, A.; Barrett, A. M.; Collins, G. S.; Soare, R. J.

2018-03-01

Polygonal networks of patterned ground are a common feature in cold-climate environments. They can form through the thermal contraction of ice-cemented sediment (i.e. formed from fractures), or the freezing and thawing of ground ice (i.e. formed by patterns of clasts, or ground deformation). The characteristics of these landforms provide information about environmental conditions. Analogous polygonal forms have been observed on Mars leading to inferences about environmental conditions. We have identified clastic polygonal features located around Lyot crater, Mars (50°N, 30°E). These polygons are unusually large (>100 m diameter) compared to terrestrial clastic polygons, and contain very large clasts, some of which are up to 15 metres in diameter. The polygons are distributed in a wide arc around the eastern side of Lyot crater, at a consistent distance from the crater rim. Using high-resolution imaging data, we digitised these features to extract morphological information. These data are compared to existing terrestrial and Martian polygon data to look for similarities and differences and to inform hypotheses concerning possible formation mechanisms. Our results show the clastic polygons do not have any morphometric features that indicate they are similar to terrestrial sorted, clastic polygons formed by freeze-thaw processes. They are too large, do not show the expected variation in form with slope, and have clasts that do not scale in size with polygon diameter. However, the clastic networks are similar in network morphology to thermal contraction cracks, and there is a potential direct Martian analogue in a sub-type of thermal contraction polygons located in Utopia Planitia. Based upon our observations, we reject the hypothesis that polygons located around Lyot formed as freeze-thaw polygons and instead an alternative mechanism is put forward: they result from the infilling of earlier thermal contraction cracks by wind-blown material, which then became

Neutron total scattering cross sections of elemental antimony

Energy Technology Data Exchange (ETDEWEB)

Smith, A.B.; Guenther, P.T.; Whalen, J.F.

1982-11-01

Neutron total cross sections are measured from 0.8 to 4.5 MeV with broad resolutions. Differential-neutron-elastic-scattering cross sections are measured from 1.5 to 4.0 MeV at intervals of 50 to 200 keV and at scattering angles distributed between 20 and 160 degrees. Lumped-level neutron-inelastic-scattering cross sections are measured over the same angular and energy range. The exPerimental results are discussed in terms of an optical-statistical model and are compared with respective values given in ENDF/B-V.

Neutron total scattering cross sections of elemental antimony

International Nuclear Information System (INIS)

Smith, A.B.; Guenther, P.T.; Whalen, J.F.

1982-11-01

Neutron total cross sections are measured from 0.8 to 4.5 MeV with broad resolutions. Differential-neutron-elastic-scattering cross sections are measured from 1.5 to 4.0 MeV at intervals of 50 to 200 keV and at scattering angles distributed between 20 and 160 degrees. Lumped-level neutron-inelastic-scattering cross sections are measured over the same angular and energy range. The exPerimental results are discussed in terms of an optical-statistical model and are compared with respective values given in ENDF/B-V

Total cross sections for heavy flavour production at HERA

CERN Document Server

Frixione, Stefano; Nason, P; Ridolfi, G; Frixione, S; Mangano, M L; Nason, P; Ridolfi, G

1995-01-01

We compute total cross sections for charm and bottom photoproduction at HERA energies, and discuss the relevant theoretical uncertainties. In particular we discuss the problems arising from the small-x region, the uncertainties in the gluon parton density, and the uncertainties in the hadronic component of the cross section. Total electroproduction cross sections, calculated in the Weizs\\"acker-Williams approximation, are also given.

Heavy flavour hadro-production cross-sections

CERN Document Server

Wöhri, H K

2003-01-01

Hadro-production data on charm and beauty absolute cross-sections, collected by experiments at CERN, DESY and Fermilab, are reviewed. The measurements, corrected for the 'time evolution' of the branching ratios, are compared to calculations done with Pythia, as a function of the collision energy, using the latest parametrizations of the parton densities. We then estimate some charm and beauty production cross-sections relevant for future measurements, including nuclear effectes in the PDFs. We finish by briefly addressing the relevance, in heavy-ion collisions, of beauty production as feed-down for J/psi production.

Evaluated activation cross-sections and intercomparison of the ...

Indian Academy of Sciences (India)

mental data cross-section with the theoretical codes, to study the quality of the theoretical ... the cross-section, angular distribution, double differential data, gamma ..... TALYS. TENDL. Figure 6. Excitation function of the 87Sr(p, 2n)86Y reaction.

Sequential and Parallel Algorithms for Finding a Maximum Convex Polygon

DEFF Research Database (Denmark)

Fischer, Paul

1997-01-01

This paper investigates the problem where one is given a finite set of n points in the plane each of which is labeled either ?positive? or ?negative?. We consider bounded convex polygons, the vertices of which are positive points and which do not contain any negative point. It is shown how...... such a polygon which is maximal with respect to area can be found in time O(n³ log n). With the same running time one can also find such a polygon which contains a maximum number of positive points. If, in addition, the number of vertices of the polygon is restricted to be at most M, then the running time...... becomes O(M n³ log n). It is also shown how to find a maximum convex polygon which contains a given point in time O(n³ log n). Two parallel algorithms for the basic problem are also presented. The first one runs in time O(n log n) using O(n²) processors, the second one has polylogarithmic time but needs O...

Positron induced scattering cross sections for hydrocarbons relevant to plasma

Science.gov (United States)

Singh, Suvam; Antony, Bobby

2018-05-01

This article explores positron scattering cross sections by simple hydrocarbons such as ethane, ethene, ethyne, propane, and propyne. Chemical erosion processes occurring on the surface due to plasma-wall interactions are an abundant source of hydrocarbon molecules which contaminate the hydrogenic plasma. These hydrocarbons play an important role in the edge plasma region of Tokamak and ITER. In addition to this, they are also one of the major components in the planetary atmospheres and astrophysical mediums. The present work focuses on calculation of different positron impact interactions with simple hydrocarbons in terms of the total cross section (Qtot), elastic cross section (Qel), direct ionization cross section (Qion), positronium formation cross section (Qps), and total ionization cross section (Qtion). Knowing that the positron-plasma study is one of the trending fields, the calculated data have diverse plasma and astrophysical modeling applications. A comprehensive study of Qtot has been provided where the inelastic cross sections have been reported for the first time. Comparisons are made with those available from the literature, and a good agreement is obtained with the measurements.

Neutron standard cross sections in reactor physics - Need and status

International Nuclear Information System (INIS)

Carlson, A.D.

1990-01-01

The design and improvement of nuclear reactors require detailed neutronics calculations. These calculations depend on comprehensive libraries of evaluated nuclear cross sections. Most of the cross sections that form the data base for these evaluations have been measured relative to neutron cross-section standards. The use of these standards can often simplify the measurement process by eliminating the need for a direct measurement of the neutron fluence. The standards are not known perfectly, however; thus the accuracy of a cross-section measurement is limited by the uncertainty in the standard cross section relative to which it is measured. Improvements in a standard cause all cross sections measured relative to that standard to be improved. This is the reason for the emphasis on improving the neutron cross-section standards. The continual process of measurement and evaluation has led to improvements in the accuracy and range of applicability of the standards. Though these improvements have been substantial, this process must continue in order to obtain the high-quality standards needed by the user community

Evaluation of kerma in carbon and the carbon cross sections

International Nuclear Information System (INIS)

Axton, E.J.

1992-02-01

A preliminary simultaneous least squares fit to measurements of kerma in carbon, and carbon cross sections taken from the ENDF/B-V file was carried out. In the calculation the shapes of the total cross section and the various partial cross sections were rigid but their absolute values were allowed to float in the fit within the constraints of the ENDF/B-V uncertainties. The construction of the ENDF/B-V file imposed improbable shapes, particularly in the case of the (12)C(n,n'3(alpha)) reaction, which were incompatible with direct measurements of kerma and of the reaction cross sections. Consequently a new evaluation of the cross section data became necessary. Since the available time was limited the new evaluation concentrated particularly on those aspects of the ENDF/B-V carbon file which would have most impact on kerma calculations. Following the new evaluation of cross sections new tables of kerma factors were produced. Finally, the simultaneous least squares fit to measurements of kerma and the new cross section file was repeated

single-top quark production cross section using the ATLAS detector

CERN Document Server

Feng, Cunfeng; The ATLAS collaboration

2014-01-01

Measurements of single top-quark production cross section in proton proton collisions at 7 and 8 TeV are presented. In the leading order process, a W boson is exchanged in the t-channel. For this process, for the first time a fiducial cross section measured within the detector acceptance is presented and the modelling uncertainty when extrapolating to the total inclusive cross section is assessed with a large number of different Monte Carlo generators. The result is in good agreement with the most up-to-date theory predictions. Furthermore, the single top-quark and anti-top total production cross sections, their ratio, as well as a measurement of the inclusive production cross section is presented. Differential cross sections are measured as a function of the transverse momentum and the absolute value of the rapidity of top and anti-top quarks. In addition, a measurement of the production cross section of a single top quark in association with a W boson is presented. The s-channel production is explored and l...

Effects of cross-section on mechanical properties of Au nanowire

Energy Technology Data Exchange (ETDEWEB)

Vazinishayan, Ali; Yang, Shuming, E-mail: shuming.yang@mail.xjtu.edu.cn; Duongthipthewa, Anchalee; Wang, Yiming [State Key Laboratory for manufacturing system engineering, Xi’an Jiaotong University, Xi’an, 710049 (China)

2016-02-15

The aim of this paper is study of the effects of multiple cross-section of Au nanowire on mechanical properties. Different cross-section models of Au nanowires including circular, hexagonal, pentagonal and rectangular were simulated by finite element modeling using ABAQUS. In this study, the bending technique was applied so that both ends of the model were clamped with mid-span under loading condition. The cross-sections had the length of 400 nm and the diameter of 40 nm, except the circular cross-section while the rest of the cross-sections had an equivalent diameter. Von Misses stresses distribution were used to define the stress distribution in the cross-section under loading condition, and elastic deformation was analyzed by the beam theory. The results disclosed that the circular and the rectangular models had highest and lowest strengths against plastic deformation, respectively.

Invisible anti-cloak with elliptic cross section using phase complement

International Nuclear Information System (INIS)

Yang Yu-Qi; Zhang Min; Yue Jian-Xiang

2011-01-01

Based on the theory of phase complement, an anti-cloak with circular cross section can be made invisible to an object outside its domain. As the cloak with elliptic cross section is more effective to make objects invisible than that with circular cross section, a scaled coordinate system is proposed to design equivalent materials of invisible anti-cloak with elliptic cross section using phase complement. The cloaks with conventional dielectric and double negative parameters are both simulated with the geometrical transformations. The results show that the cloak with elliptic cross section through phase complement can effectively hide the outside objects. (classical areas of phenomenology)

Methods for calculating anisotropic transfer cross sections

International Nuclear Information System (INIS)

Cai, Shaohui; Zhang, Yixin.

1985-01-01

The Legendre moments of the group transfer cross section, which are widely used in the numerical solution of the transport calculation can be efficiently and accurately constructed from low-order (K = 1--2) successive partial range moments. This is convenient for the generation of group constants. In addition, a technique to obtain group-angle correlation transfer cross section without Legendre expansion is presented. (author)

Photoionization cross sections: present status and future needs

International Nuclear Information System (INIS)

Manson, S.T.

1988-01-01

The existing experimental data situation for photoionization cross section of ground-state atoms, excited states and positive ions is reviewed. The ability of theory to predict these cross sections is also discussed. The likely progress for the near future is presented [pt

Neutrino-nucleus cross sections for oscillation experiments

Science.gov (United States)

Katori, Teppei; Martini, Marco

2018-01-01

Neutrino oscillations physics is entering an era of high precision. In this context, accelerator-based neutrino experiments need a reduction in systematic errors to the level of a few percent. Today, one of the most important sources of systematic errors are neutrino-nucleus cross sections which, in the energy region of hundreds of MeV to a few GeV, are known to a precision not exceeding 20%. In this article we review the present experimental and theoretical knowledge of neutrino-nucleus interaction physics. After introducing neutrino-oscillation physics and accelerator-based neutrino experiments, we give an overview of general aspects of neutrino-nucleus cross sections, from both the theoretical and experimental point of view. Then, we focus on these cross sections in different reaction channels. We start with the quasi-elastic and quasi-elastic-like cross section, placing a special emphasis on the multinucleon emission channel, which has attracted a lot of attention in the last few years. We review the main aspects of the different microscopic models for this channel by discussing analogies and the differences among them. The discussion is always driven by a comparison with the experimental data. We then consider the one-pion production channel where agreement between data and theory remains highly unsatisfactory. We describe how to interpret pion data, and then analyze, in particular, the puzzle related to the difficulty of theoretical models and Monte Carlo to simultaneously describe MiniBooNE and MINERvA experimental results. Inclusive cross sections are also discussed, as well as the comparison between the {ν }μ and {ν }e cross sections, relevant for the charge-conjugation-parity violation experiments. The impact of nuclear effects on the reconstruction of neutrino energy and on the determination of the neutrino-oscillation parameters is also reviewed. Finally, we look to the future by discussing projects and efforts in relation to future detectors, beams

Inclined Bodies of Various Cross Sections at Supersonic Speeds

Science.gov (United States)

Jorgensen, Leland H.

1958-01-01

To aid in assessing effects of cross-sectional shape on body aerodynamics, the forces and moments have been measured for bodies with circular, elliptic, square, and triangular cross sections at Mach numbers 1.98 and 3.88. Results for bodies with noncircular cross sections have been compared with results for bodies of revolution having the same axial distribution of cross-sectional area (and, thus, the same equivalent fineness ratio). Comparisons have been made for bodies of fineness ratios 6 and 10 at angles of attack from 0 deg to about 20 deg and for Reynolds numbers, based on body length, of 4.0 x 10(exp 6) and 6.7 x 10(exp 6). The results of this investigation show that distinct aerodynamic advantages can be obtained by using bodies with noncircular cross sections. At certain angles of bank, bodies with elliptic, square, and triangular cross sections develop considerably greater lift and lift-drag ratios than equivalent bodies of revolution. For bodies with elliptic cross sections, lift and pitching-moment coefficients can be correlated with corresponding coefficients for equivalent circular bodies. It has been found that the ratios of lift and pitching-moment coefficients for an elliptic body to those for an equivalent circular body are practically constant with change in both angle of attack and Mach number. These lift and moment ratios are given very accurately by slender-body theory. As a result of this agreement, the method of NACA Rep. 1048 for computing forces and moments for bodies of revolution has been simply extended to bodies with elliptic cross sections. For the cases considered (elliptic bodies of fineness ratios 6 and 10 having cross-sectional axis ratios of 1.5 and 2), agreement of theory with experiment is very good. As a supplement to the force and moment results, visual studies of the flow over bodies have been made by use of the vapor-screen, sublimation, and white-lead techniques. Photographs from these studies are included in the report.

On the mean and variance of the writhe of random polygons

International Nuclear Information System (INIS)

Portillo, J; Scharein, R; Arsuaga, J; Vazquez, M; Diao, Y

2011-01-01

We here address two problems concerning the writhe of random polygons. First, we study the behavior of the mean writhe as a function length. Second, we study the variance of the writhe. Suppose that we are dealing with a set of random polygons with the same length and knot type, which could be the model of some circular DNA with the same topological property. In general, a simple way of detecting chirality of this knot type is to compute the mean writhe of the polygons; if the mean writhe is non-zero then the knot is chiral. How accurate is this method? For example, if for a specific knot type K the mean writhe decreased to zero as the length of the polygons increased, then this method would be limited in the case of long polygons. Furthermore, we conjecture that the sign of the mean writhe is a topological invariant of chiral knots. This sign appears to be the same as that of an 'ideal' conformation of the knot. We provide numerical evidence to support these claims, and we propose a new nomenclature of knots based on the sign of their expected writhes. This nomenclature can be of particular interest to applied scientists. The second part of our study focuses on the variance of the writhe, a problem that has not received much attention in the past. In this case, we focused on the equilateral random polygons. We give numerical as well as analytical evidence to show that the variance of the writhe of equilateral random polygons (of length n) behaves as a linear function of the length of the equilateral random polygon.

On the mean and variance of the writhe of random polygons.

Science.gov (United States)

Portillo, J; Diao, Y; Scharein, R; Arsuaga, J; Vazquez, M

We here address two problems concerning the writhe of random polygons. First, we study the behavior of the mean writhe as a function length. Second, we study the variance of the writhe. Suppose that we are dealing with a set of random polygons with the same length and knot type, which could be the model of some circular DNA with the same topological property. In general, a simple way of detecting chirality of this knot type is to compute the mean writhe of the polygons; if the mean writhe is non-zero then the knot is chiral. How accurate is this method? For example, if for a specific knot type K the mean writhe decreased to zero as the length of the polygons increased, then this method would be limited in the case of long polygons. Furthermore, we conjecture that the sign of the mean writhe is a topological invariant of chiral knots. This sign appears to be the same as that of an "ideal" conformation of the knot. We provide numerical evidence to support these claims, and we propose a new nomenclature of knots based on the sign of their expected writhes. This nomenclature can be of particular interest to applied scientists. The second part of our study focuses on the variance of the writhe, a problem that has not received much attention in the past. In this case, we focused on the equilateral random polygons. We give numerical as well as analytical evidence to show that the variance of the writhe of equilateral random polygons (of length n ) behaves as a linear function of the length of the equilateral random polygon.

Self-Assembly of Flux-Closure Polygons from Magnetite Nanocubes.

Science.gov (United States)

Szyndler, Megan W; Corn, Robert M

2012-09-06

Well-defined nanoscale flux-closure polygons (nanogons) have been fabricated on hydrophilic surfaces from the face-to-face self-assembly of magnetite nanocubes. Uniform ferrimagnetic magnetite nanocubes (∼86 nm) were synthesized and characterized with a combination of electron microscopy, diffraction, and magnetization measurements. The nanocubes were subsequently cast onto hydrophilic substrates, wherein the cubes lined up face-to-face and formed a variety of polygons due to magnetostatic and hydrophobic interactions. The generated surfaces consist primarily of three- and four-sided nanogons; polygons ranging from two to six sides were also observed. Further examination of the nanogons showed that the constraints of the face-to-face assembly of nanocubes often led to bowed sides, strained cube geometries, and mismatches at the acute angle vertices. Additionally, extra nanocubes were often present at the vertices, suggesting the presence of external magnetostatic fields at the polygon corners. These nanogons are inimitable nanoscale magnetic structures with potential applications in the areas of magnetic memory storage and high-frequency magnetics.

Priority cross-sections. Joint Nordic analyses of important cross-sections in the Nordel system. Main report

Energy Technology Data Exchange (ETDEWEB)

NONE

2004-06-01

The Nordic Grid Master Plan 2002 shed light on the energy and power balance for the Nordel area but with special focus on 2005. There was a lot to suggest that the tradi-tional transport patterns with frequent southbound transports would change and be more frequently replaced by northbound transports. Against this background, a number of cross-sections were identified within the Nordel area where expansion is expected to have considerable significance for the Nordic elec-tricity market. The present report 'Priority Cross-sections' concludes the work which was started with the grid master plan. The priority cross-sections are subjected to a technical and socio-economic analysis. The analysis aims to understand the transports in the Nordel system and to support Nor-del when prioritizing forthcoming initiatives. The market price is the driving force for the initiatives which will be carried out on the supply and demand side. The commissioning and decommissioning of commercial pro-duction capacity is determined by the market players, and the task of the transmission system operators (TSOs) is to ensure a robust infrastructure for the smooth operation of the electricity market. (au)

Measurement of actinide neutron cross sections

International Nuclear Information System (INIS)

Firestone, Richard B.; Nitsche, Heino; Leung, Ka-Ngo; Perry, DaleL.; English, Gerald

2003-01-01

The maintenance of strong scientific expertise is critical to the U.S. nuclear attribution community. It is particularly important to train students in actinide chemistry and physics. Neutron cross-section data are vital components to strategies for detecting explosives and fissile materials, and these measurements require expertise in chemical separations, actinide target preparation, nuclear spectroscopy, and analytical chemistry. At the University of California, Berkeley and the Lawrence Berkeley National Laboratory we have trained students in actinide chemistry for many years. LBNL is a leader in nuclear data and has published the Table of Isotopes for over 60 years. Recently, LBNL led an international collaboration to measure thermal neutron capture radiative cross sections and prepared the Evaluated Gamma-ray Activation File (EGAF) in collaboration with the IAEA. This file of 35, 000 prompt and delayed gamma ray cross-sections for all elements from Z=1-92 is essential for the neutron interrogation of nuclear materials. LBNL has also developed new, high flux neutron generators and recently opened a 1010 n/s D+D neutron generator experimental facility

Virginia ESI: INDEX (Index Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains vector polygons representing the boundaries of all hardcopy cartographic products produced as part of the Environmental Sensitivity Index...

238U subthreshold neutron induced fission cross section

International Nuclear Information System (INIS)

Difilippo, F.C.; Perez, R.B.; De Saussure, G.; Olsen, D.K.; Ingle, R.W.

1976-01-01

High resolution measurements of the 238 U neutron induced fission cross section are reported for neutron energies between 600 eV and 2 MeV. The average subthreshold fission cross section between 10 and 100 keV was found to be 44 +- 6 μb

[The psychological effects of taking in "Shikohin": A cross-sectional exploratory study].

Science.gov (United States)

Yokomitsu, Kengo; Kanai, Yoshihiro; Matsuki, Shuhei; Hirai, Hiroto; Iizuka, Tomoki; Wakasa, Komihiro; Akatsuka, Tomoaki; Sato, Kenji; Sakano, Yuji

2015-10-01

This study explores the psychological effects that Japanese people experience when consuming their "Shikohin", such as alcohol, tea, coffee, and tobacco. We'conducted a cross-sectional study among 542 people, from 20-to 69-year-old; who regularly consumed any one of "Shikohin" in Tokyo, Kanagawa, Saitama, and Chiba. The participants responded to an anonymous questionnaire concerning the consumption patterns of their "Shikohin" and the psychological effects that they experienced in taking in their "Shikohin". Results obtained using the K-J methods showed three common psychological effects in each "Shikohin". These effects included an increase in relaxation response, the promotion of social relationships, and an increase in positive mood. Our findings suggest that Japanese people may get some common effects through consumption of different "Shikohin".

Fission cross sections in the intermediate energy region

International Nuclear Information System (INIS)

Lisowski, P.W.; Gavron, A.; Parker, W.E.; Ullmann, J.L.; Balestrini, S.J.; Carlson, A.D.; Wasson, O.A.; Hill, N.W.

1991-01-01

Until recently there has been very little cross section data for neutron-induced fission in the intermediate energy region, primarily because no suitable neutron source has existed. At Los Alamos, the WNR target-4 facility provides a high-intensity source of neutrons nearly ideal for fission measurements extending from a fraction of a MeV to several hundred MeV. This paper summarizes the status of fission cross section data in the intermediate energy range (En > 30 MeV) and presents our fission cross section data for 235 U and 238 U compared to intranuclear cascade and statistical model predictions

Fission cross sections in the intermediate energy region

Energy Technology Data Exchange (ETDEWEB)

Lisowski, P.W.; Gavron, A.; Parker, W.E.; Ullmann, J.L.; Balestrini, S.J. (Los Alamos National Lab., NM (USA)); Carlson, A.D.; Wasson, O.A. (National Inst. of Standards and Technology, Gaithersburg, MD (USA)); Hill, N.W. (Oak Ridge National Lab., TN (USA))

1991-01-01

Until recently there has been very little cross section data for neutron-induced fission in the intermediate energy region, primarily because no suitable neutron source has existed. At Los Alamos, the WNR target-4 facility provides a high-intensity source of neutrons nearly ideal for fission measurements extending from a fraction of a MeV to several hundred MeV. This paper summarizes the status of fission cross section data in the intermediate energy range (En > 30 MeV) and presents our fission cross section data for {sup 235}U and {sup 238}U compared to intranuclear cascade and statistical model predictions.

Convex lattice polygons of fixed area with perimeter-dependent weights.

Science.gov (United States)

Rajesh, R; Dhar, Deepak

2005-01-01

We study fully convex polygons with a given area, and variable perimeter length on square and hexagonal lattices. We attach a weight tm to a convex polygon of perimeter m and show that the sum of weights of all polygons with a fixed area s varies as s(-theta(conv))eK(t)square root(s) for large s and t less than a critical threshold tc, where K(t) is a t-dependent constant, and theta(conv) is a critical exponent which does not change with t. Using heuristic arguments, we find that theta(conv) is 1/4 for the square lattice, but -1/4 for the hexagonal lattice. The reason for this unexpected nonuniversality of theta(conv) is traced to existence of sharp corners in the asymptotic shape of these polygons.

Polynomial parameterized representation of macroscopic cross section for PWR reactor

International Nuclear Information System (INIS)

Fiel, Joao Claudio B.

2015-01-01

The purpose of this work is to describe, by means of Tchebychev polynomial, a parameterized representation of the homogenized macroscopic cross section for PWR fuel element as a function of soluble boron concentration, moderator temperature, fuel temperature, moderator density and 235 U 92 enrichment. Analyzed cross sections are: fission, scattering, total, transport, absorption and capture. This parameterization enables a quick and easy determination of the problem-dependent cross-sections to be used in few groups calculations. The methodology presented here will enable to provide cross-sections values to perform PWR core calculations without the need to generate them based on computer code calculations using standard steps. The results obtained by parameterized cross-sections functions, when compared with the cross-section generated by SCALE code calculations, or when compared with K inf , generated by MCNPX code calculations, show a difference of less than 0.7 percent. (author)

Small-Scale Polygons and the History of Ground Ice on Mars

Science.gov (United States)

Mellon, Michael T.

2000-01-01

This research has laid a foundation for continued study of permafrost polygons on Mars using the models and understanding discussed here. Further study of polygonal patterns on Mars is proceeding (under new funding) which is expected to reveal more results about the origin of observed martian polygons and what information they contain regarding the recent history of tile martian climate and of water ice on Mars.

Beam envelope profile of non-centrosymmetric polygonal phase space

International Nuclear Information System (INIS)

Chen Yinbao; Xie Xi

1984-01-01

The general theory of beam envelope profile of non-centrosymmetric polygonal phase space is developed. By means of this theory the beam envelope profile of non-centrosymmetric polygonal phase space can be calculated directly. An example is carried out in detail to show the practical application of the theory

Damage energy and displacement cross sections: survey and sensitivity

International Nuclear Information System (INIS)

Doran, D.G.; Parkin, D.M.; Robinson, M.T.

1976-10-01

Calculations of damage energy and displacement cross sections using the recommendations of a 1972 IAEA Specialists' Meeting are reviewed. The sensitivity of the results to assumptions about electronic energy losses in cascade development and to different choices respecting the nuclear cross sections is indicated. For many metals, relative uncertainties and sensitivities in these areas are sufficiently small that adoption of standard displacement cross sections for neutron irradiations can be recommended

Cross section recondensation method via generalized energy condensation theory

International Nuclear Information System (INIS)

Douglass, Steven; Rahnema, Farzad

2011-01-01

Highlights: → A new method is presented which corrects for core environment error from specular boundaries at the lattice cell level. → Solution obtained with generalized energy condensation provides improved approximation to the core level fine-group flux. → Iterative recondensation of the cross sections and unfolding of the flux provides on-the-fly updating of the core cross sections. → Precomputation of energy integrals and fine-group cross sections allows for easy implementation and efficient solution. → Method has been implemented in 1D and shown to correct the environment error, particularly in strongly heterogeneous cores. - Abstract: The standard multigroup method used in whole-core reactor analysis relies on energy condensed (coarse-group) cross sections generated from single lattice cell calculations, typically with specular reflective boundary conditions. Because these boundary conditions are an approximation and not representative of the core environment for that lattice, an error is introduced in the core solution (both eigenvalue and flux). As current and next generation reactors trend toward increasing assembly and core heterogeneity, this error becomes more significant. The method presented here corrects for this error by generating updated coarse-group cross sections on-the-fly within whole-core reactor calculations without resorting to additional cell calculations. In this paper, the fine-group core flux is unfolded by making use of the recently published Generalized Condensation Theory and the cross sections are recondensed at the whole-core level. By iteratively performing this recondensation, an improved core solution is found in which the core-environment has been fully taken into account. This recondensation method is both easy to implement and computationally very efficient because it requires precomputation and storage of only the energy integrals and fine-group cross sections. In this work, the theoretical basis and development

Poster - 18: New features in EGSnrc for photon cross sections

Energy Technology Data Exchange (ETDEWEB)

Ali, Elsayed; Mainegra-Hing, Ernesto; Rogers, David W.O. [The Ottawa Hospital Cancer Centre, National Research Council Canada, Carleton University (Canada)

2016-08-15

Purpose: To implement two new features in the EGSnrc Monte Carlo system. The first is an option to account for photonuclear attenuation, which can contribute a few percent to the total cross section at the higher end of the energy range of interest to medical physics. The second is an option to use exact NIST XCOM photon cross sections. Methods: For the first feature, the photonuclear total cross sections are generated from the IAEA evaluated data. In the current, first-order implementation, after a photonuclear event, there is no energy deposition or secondary particle generation. The implementation is validated against deterministic calculations and experimental measurements of transmission signals. For the second feature, before this work, if the user explicitly requested XCOM photon cross sections, EGSnrc still used its own internal incoherent scattering cross sections. These differ by up to 2% from XCOM data between 30 keV and 40 MeV. After this work, exact XCOM incoherent scattering cross sections are an available option. Minor interpolation artifacts in pair and triplet XCOM cross sections are also addressed. The default for photon cross section in EGSnrc is XCOM except for the new incoherent scattering cross sections, which have to be explicitly requested. The photonuclear, incoherent, pair and triplet data from this work are available for elements and compounds for photon energies from 1 keV to 100 GeV. Results: Both features are implemented and validated in EGSnrc.Conclusions: The two features are part of the standard EGSnrc distribution as of version 4.2.3.2.

MINERvA - neutrino nucleus cross section experiment

CERN Multimedia

CERN. Geneva

2014-01-01

Recent results from MINERvA, a neutrino cross section experiment at Fermilab, are presented. MINERVA has the goal of providing precision results which will have important impact on oscillation experiments.  Initial data runs for muon neutrino and antineutrino beams of ~3.5 GeV have produced a large number of new results. This seminar will introduce the experiment and describe results for quasielastic, pion production, and inclusive cross sections.

Evaluation methods for neutron cross section standards

International Nuclear Information System (INIS)

Bhat, M.R.

1980-01-01

Methods used to evaluate the neutron cross section standards are reviewed and their relative merits, assessed. These include phase-shift analysis, R-matrix fit, and a number of other methods by Poenitz, Bhat, Kon'shin and the Bayesian or generalized least-squares procedures. The problems involved in adopting these methods for future cross section standards evaluations are considered, and the prospects for their use, discussed. 115 references, 5 figures, 3 tables

Evaluation of cross sections for neutron-induced reactions in sodium

International Nuclear Information System (INIS)

Larson, D.C.

1980-09-01

An evaluation of the neutron-induced cross sections of 23 Na has been done for the energy range from 10 -5 eV to 20 MeV. All significant cross sections are given, including differential cross sections for production of gamma rays. The recommended values are based on experimental data where available, and use results of a consistent model code analysis of available data to predict cross sections where there are no experimental data. This report describes the evaluation that was submitted to the Cross Section Evaluation Working Group (CSEWG) for consideration as a part of the Evaluated Nuclear Data File, Version V, and subsequently issued as MAT 1311. 126 references, 130 figures, 14 tables

Maryland ESI: FISH (Fish Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for marine, estuarine, anadromous, and freshwater fish species in Maryland. Vector polygons in this data...

Alabama ESI: INVERT (Invertebrate Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for marine and estuarine invertebrate species in Alabama. Vector polygons in this data set represent...

Virginia ESI: INVERT (Invertebrate Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for marine, estuarine, and rare invertebrate species in Virginia. Vector polygons in this data set...

Louisiana ESI: BIRDS (Bird Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for waterfowl species and shorebirds in coastal Louisiana. Vector polygons in this data set represent...

Virginia ESI: FISH (Fish Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for marine, estuarine, anadromous, and brackishwater fish species in Virginia. Vector polygons in this data...

Louisiana ESI: FISH (Fish Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for freshwater (inland) fish species in coastal Louisiana. Vector polygons represent water-bodies and other...

Differential bremsstrahlung and pair production cross sections at high energies

International Nuclear Information System (INIS)

Olsen, Haakon A.

2003-01-01

Detailed differential cross sections for high energy bremsstrahlung and pair production are derived with specific attention to the differences between the two processes, which are considerable. For the integrated cross sections, which are the only cross sections specifically known until now, the final state integration theorem guarantees that the exact cross section formulas can be exchanged between bremsstrahlung and pair production by the same substitution rules as for the Born-approximation Bethe-Heitler cross sections, for any amount of atomic screening. In fact the theorem states that the Coulomb corrections to the integrated bremsstrahlung and pair production cross sections are identical for any amount of screening. The analysis of the basic differential cross sections leads to fundamental physical differences between bremsstrahlung and pair production. Coulomb corrections occur for pair production in the strong electric field of the atom for 'large' momentum transfer of the order of mc. For bremsstrahlung, on the other hand, the Coulomb corrections take place at a 'large' distance from the atom of the order of ((ℎ/2π)/mc)ε, with a 'small' momentum transfer mc/ε, where ε is the initial electron energy in units of mc 2 . And the Coulomb corrections can be large, of the order of larger than (Z/137) 2 , which is considerably larger than the integrated cross section corrections

Systematic study of three-nucleon force effects in the cross section of the deuteron-proton breakup at 130 MeV

International Nuclear Information System (INIS)

St. Kistryn; E. Stephan; A. Biegun; K. Bodek; A. Deltuva; E. Epelbaum; K. Ermisch; W. Gloeckle; J. Golak; N. Kalantar-Nayestanaki; H. Kamada; M. Kis; B. Klos; A. Kozela; J. Kuros-Zolnierczuk; M. Mahjour-Shafiei; U.-G. Meissner; A. Micherdzinska; A. Nogga; P. U. Sauer; R. Skibinski; R. Sworst; H. Witala; J. Zejma; W. Zipper

2005-01-01

High precision cross-section data of the deuteron-proton breakup reaction at 130 MeV are presented for 72 kinematically complete configurations. The data cover a large region of the available phase space, divided into a systematic grid of kinematical variables. They are compared with theoretical predictions, in which the full dynamics of the three-nucleon (3N) system is obtained in three different ways: realistic nucleon-nucleon (NN) potentials are combined with model 3N forces (3NF's) or with an effective 3NF resulting from explicit treatment of the Delta-isobar excitation. Alternatively, the chiral perturbation theory approach is used at the next-to-next-to-leading order with all relevant NN and 3N contributions taken into account. The generated dynamics is then applied to calculate cross-section values by rigorous solution of the 3N Faddeev equations. The comparison of the calculated cross sections with the experimental data shows a clear preference for the predictions in which the 3NF's are included. The majority of the experimental data points is well reproduced by the theoretical predictions. The remaining discrepancies are investigated by inspecting cross sections integrated over certain kinematical variables. The procedure of global comparisons leads to establishing regularities in disagreements between the experimental data and the theoretically predicted values of the cross sections. They indicate deficiencies still present in the assumed models of the 3N system dynamics

A simple algorithm for computing positively weighted straight skeletons of monotone polygons.

Science.gov (United States)

Biedl, Therese; Held, Martin; Huber, Stefan; Kaaser, Dominik; Palfrader, Peter

2015-02-01

We study the characteristics of straight skeletons of monotone polygonal chains and use them to devise an algorithm for computing positively weighted straight skeletons of monotone polygons. Our algorithm runs in [Formula: see text] time and [Formula: see text] space, where n denotes the number of vertices of the polygon.

Development of polygon elements based on the scaled boundary finite element method

International Nuclear Information System (INIS)

Chiong, Irene; Song Chongmin

2010-01-01

We aim to extend the scaled boundary finite element method to construct conforming polygon elements. The development of the polygonal finite element is highly anticipated in computational mechanics as greater flexibility and accuracy can be achieved using these elements. The scaled boundary polygonal finite element will enable new developments in mesh generation, better accuracy from a higher order approximation and better transition elements in finite element meshes. Polygon elements of arbitrary number of edges and order have been developed successfully. The edges of an element are discretised with line elements. The displacement solution of the scaled boundary finite element method is used in the development of shape functions. They are shown to be smooth and continuous within the element, and satisfy compatibility and completeness requirements. Furthermore, eigenvalue decomposition has been used to depict element modes and outcomes indicate the ability of the scaled boundary polygonal element to express rigid body and constant strain modes. Numerical tests are presented; the patch test is passed and constant strain modes verified. Accuracy and convergence of the method are also presented and the performance of the scaled boundary polygonal finite element is verified on Cook's swept panel problem. Results show that the scaled boundary polygonal finite element method outperforms a traditional mesh and accuracy and convergence are achieved from fewer nodes. The proposed method is also shown to be truly flexible, and applies to arbitrary n-gons formed of irregular and non-convex polygons.

Positron total scattering cross-sections for alkali atoms

Science.gov (United States)

Sinha, Nidhi; Singh, Suvam; Antony, Bobby

2018-01-01

Positron-impact total scattering cross-sections for Li, Na, K, Rb, Cs and Fr atoms are calculated in the energy range from 5-5000 eV employing modified spherical complex optical potential formalism. The main aim of this work is to apply this formalism to the less studied positron-target collision systems. The results are compared with previous theoretical and experimental data, wherever available. In general, the present data show overall agreement and consistency with other results. Furthermore, we have done a comparative study of the results to investigate the effect of atomic size on the cross-sections as we descend through the group in the periodic table. We have also plotted a correlation graph of the present total cross-sections with polarizability and number of target electrons. The two correlation plots confirm the credibility and consistency of the present results. Besides, this is the first theoretical attempt to report positron-impact total cross-sections of alkali atoms over such a wide energy range.

Nanopatterning by molecular polygons.

Science.gov (United States)

Jester, Stefan-S; Sigmund, Eva; Höger, Sigurd

2011-07-27

Molecular polygons with three to six sides and binary mixtures thereof form long-range ordered patterns at the TCB/HOPG interface. This includes also the 2D crystallization of pentagons. The results provide an insight into how the symmetry of molecules is translated into periodic structures.

SQUEEZING EFFECT OF RAIL LOADED BY SEMI-SLEEPERS HAVING L-SHAPED CROSS-SECTION

Directory of Open Access Journals (Sweden)

V. N. Sukhodoev

2015-01-01

Full Text Available The paper considers a problem on introduction of a conception and regularities of “squeezing effect of a rail loaded non centrally by semi-sleepers having L-shaped cross-section” exemplified by belt-type tramway. Its advantages are ensured by doubled non centrally loaded foundations these are semi-sleepers. Semi-sleeper of L-shape cross-section is a lever of L-shape form, transforming a vertical load into horizontal ones and foundation squeezing. Properties of two semi-sleepers being doubled, orientated to each other and non centrally loaded have been used in order to create a positive effect. A horizontal force creates squeezing and it is revealed as a component of a vertical load during displacements which functionally depend on foundation squeezing. These dependences demonstrate that strength and deformation properties of earth foundation of vertical direction are used for creation of horizontal properties of sleeper vertical shoulder.The paper studies mechanics pertaining to a squeezing effect of a rail loaded by semi-sleepers having L-shaped cross-section. It has been established that the rail squeezing effect results from squeezing process executed in two mutually perpendicular directions (reduction of cross-sectional area by load of a rail wheel with spacers if they are set inside of a sleeper-mechanism on an elastic foundation.Methodology for calculation of parameters on the rail reduction effect is considered as a tool for handling of applied problems on belt-type tramways. Results of the proposed rail reduction effect in problem statement for elastic conditions, with unchanged cross-sectional dimension of a rail line and introduction of correction ratio coefficients due to new initial load data have recommended for practical application as reliable values.The paper has revealed a proportional dependence of the rail reduction effect according to strength on the resultant value of reaction pressure, eccentricity difference of the

Metric inequalities for polygons

Directory of Open Access Journals (Sweden)

Adrian Dumitrescu

2013-07-01

Full Text Available Let A1,A2,…,An be the vertices of a polygon with unit perimeter, that is Σi |Ai Ai+1|=1. We derive various tight estimates on the minimum and maximum values of the sum of pairwise distances, and respectively sum of pairwise squared distances among its vertices. In most cases such estimates on these sums in the literature were known only for convex polygons.In the second part, we turn to a problem of Braß  regarding the maximum perimeter of a simplen-gon (n odd contained in a disk of unit radius. The problem was recently solved by Audet et al. 2009, who gave an exact formula. Here we present an alternative simpler proof of this formula. We then examine what happens if the simplicity condition is dropped, and obtain an exact formula for the maximum perimeter in this case as well.

Alabama ESI: FISH (Fish Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for marine, estuarine, and freshwater fish species in Alabama. Vector polygons in this data set represent...

Digitomotography in Parkinson's disease: a cross-sectional and longitudinal study.

Directory of Open Access Journals (Sweden)

Walter Maetzler

Full Text Available Motor symptoms in Parkinson's disease (PD are usually assessed with semi-quantitative tests such as the Unified PD Rating Scale (UPDRS which are limited by subjectivity, categorical design, and low sensitivity. Particularly bradykinesia as assessed e.g. with speeded index finger tapping exhibits low validity measures. This exploratory study set out to (i assess whether force transducer-based objective and quantitative analysis of motor coordination in index finger tapping is able to distinguish between PD patients and controls, and (ii assess longitudinal changes. Sixteen early-stage and 17 mid-stage PD patients as well as 18 controls were included in the cross-sectional part of the study; thirteen, 16 and 16 individuals of the respective groups agreed in a reassessment 12 months later. Frequency, force, rhythmicity, regularity and laterality of speeded and metronome paced tapping were recorded by digitomotography using a quantitative motor system ("Q-Motor". Analysis of cross-sectional data revealed most consistent differences between PD patients and controls in variability of tap performance across modalities assessed. Among PD patients, variability of taps and the ability to keep a given rhythm were associated with UPDRS motor and finger tapping scores. After 12 months, laterality parameters were reduced but no other parameters changed significantly. This data suggests that digitomotography provides quantitative and objective measures capable to differentiate PD from non-PD in a small cohort, however, the value of the assessment to track PD progression has to be further evaluated in larger cohorts of patients.

Direct Monte Carlo dose calculation using polygon-surface computational human model

International Nuclear Information System (INIS)

Jeong, Jong Hwi; Kim, Chan Hyeong; Yeom, Yeon Su; Cho, Sungkoo; Chung, Min Suk; Cho, Kun-Woo

2011-01-01

In the present study, a voxel-type computational human model was converted to a polygon-surface model, after which it was imported directly to the Geant4 code without using a voxelization process, that is, without converting back to a voxel model. The original voxel model was also imported to the Geant4 code, in order to compare the calculated dose values and the computational speed. The average polygon size of the polygon-surface model was ∼0.5 cm 2 , whereas the voxel resolution of the voxel model was 1.981 × 1.981 × 2.0854 mm 3 . The results showed a good agreement between the calculated dose values of the two models. The polygon-surface model was, however, slower than the voxel model by a factor of 6–9 for the photon energies and irradiation geometries considered in the present study, which nonetheless is considered acceptable, considering that direct use of the polygon-surface model does not require a separate voxelization process. (author)

pp production cross sections and the constraint method

International Nuclear Information System (INIS)

Anjos, J.C.; Santoro, A.F.S.; Souza, M.H.G.

1983-01-01

A method of constructing production cross sections that satisfy the constraints represented by the first few moments is shown to give an excellent account of the data when applied to the high energy pp production cross section ν sub(n) (s) plotted as functions of n. (Author) [pt

Total Cross Sections at High Energies An update

CERN Document Server

Fazal-e-Aleem, M; Alam, Saeed; Qadee-Afzal, M

2002-01-01

Current and Future measurements for the total cross sections at E-811, PP2PP, CSM, FELIX and TOTEM have been analyzed using various models. In the light of this study an attempt has been made to focus on the behavior of total cross section at very high energies.

Pion-nucleus cross sections approximation

International Nuclear Information System (INIS)

Barashenkov, V.S.; Polanski, A.; Sosnin, A.N.

1990-01-01

Analytical approximation of pion-nucleus elastic and inelastic interaction cross-section is suggested, with could be applied in the energy range exceeding several dozens of MeV for nuclei heavier than beryllium. 3 refs.; 4 tabs

Electron collision cross section sets of TMS and TEOS vapours

Science.gov (United States)

Kawaguchi, S.; Takahashi, K.; Satoh, K.; Itoh, H.

2017-05-01

Reliable and detailed sets of electron collision cross sections for tetramethylsilane [TMS, Si(CH3)4] and tetraethoxysilane [TEOS, Si(OC2H5)4] vapours are proposed. The cross section sets of TMS and TEOS vapours include 16 and 20 kinds of partial ionization cross sections, respectively. Electron transport coefficients, such as electron drift velocity, ionization coefficient, and longitudinal diffusion coefficient, in those vapours are calculated by Monte Carlo simulations using the proposed cross section sets, and the validity of the sets is confirmed by comparing the calculated values of those transport coefficients with measured data. Furthermore, the calculated values of the ionization coefficient in TEOS/O2 mixtures are compared with measured data to confirm the validity of the proposed cross section set.

Hawaii ESI: FISH (Fish Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for reef, marine, estuarine, and native stream fish species in coastal Hawaii. Vector polygons in this data...

Alabama ESI: REPTILES (Reptile Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for threatened/endangered and rare reptiles in Alabama. Vector polygons in this data set represent the rare...

Soils - Volusia County Soils (Polygons)

Data.gov (United States)

NSGIC Local Govt | GIS Inventory — Soils: 1:24000 SSURGO Map. Polygon boundaries of Soils in Volusia County, downloaded from SJRWMD and created by NRCS and SJRWMD. This data set is a digital version...

Experimentation and correlates of electronic nicotine delivery system (electronic cigarettes) among university students – A cross sectional study

OpenAIRE

K.H. Awan

2016-01-01

Objective: E-cigarettes are becoming popular among youth as safe nicotine delivery systems. Many have expressed concern, however, that e-cigarettes may serve as a gateway to future smoking, given their low perceived risk, or that their use may prevent regular smokers from quitting by maintaining their nicotine addiction. The aim of this study was to assess experimentation with and correlates of e-cigarette use among university students. Material and methods: A cross-sectional study was car...

Conformal array design on arbitrary polygon surface with transformation optics

Energy Technology Data Exchange (ETDEWEB)

Deng, Li, E-mail: dengl@bupt.edu.cn; Hong, Weijun, E-mail: hongwj@bupt.edu.cn; Zhu, Jianfeng; Peng, Biao; Li, Shufang [Beijing Key Laboratory of Network System Architecture and Convergence, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, 100876 Beijing (China); Wu, Yongle, E-mail: wuyongle138@gmail.com [Beijing Key Laboratory of Work Safety Intelligent Monitoring, School of Electronic Engineering, Beijing University of Posts and Telecommunications, 100876 Beijing (China)

2016-06-15

A transformation-optics based method to design a conformal antenna array on an arbitrary polygon surface is proposed and demonstrated in this paper. This conformal antenna array can be adjusted to behave equivalently as a uniformly spaced linear array by applying an appropriate transformation medium. An typical example of general arbitrary polygon conformal arrays, not limited to circular array, is presented, verifying the proposed approach. In summary, the novel arbitrary polygon surface conformal array can be utilized in array synthesis and beam-forming, maintaining all benefits of linear array.

Conformal array design on arbitrary polygon surface with transformation optics

International Nuclear Information System (INIS)

Deng, Li; Hong, Weijun; Zhu, Jianfeng; Peng, Biao; Li, Shufang; Wu, Yongle

2016-01-01

A transformation-optics based method to design a conformal antenna array on an arbitrary polygon surface is proposed and demonstrated in this paper. This conformal antenna array can be adjusted to behave equivalently as a uniformly spaced linear array by applying an appropriate transformation medium. An typical example of general arbitrary polygon conformal arrays, not limited to circular array, is presented, verifying the proposed approach. In summary, the novel arbitrary polygon surface conformal array can be utilized in array synthesis and beam-forming, maintaining all benefits of linear array.

Cross-Modality Image Synthesis via Weakly Coupled and Geometry Co-Regularized Joint Dictionary Learning.

Science.gov (United States)

Huang, Yawen; Shao, Ling; Frangi, Alejandro F

2018-03-01

Multi-modality medical imaging is increasingly used for comprehensive assessment of complex diseases in either diagnostic examinations or as part of medical research trials. Different imaging modalities provide complementary information about living tissues. However, multi-modal examinations are not always possible due to adversary factors, such as patient discomfort, increased cost, prolonged scanning time, and scanner unavailability. In additionally, in large imaging studies, incomplete records are not uncommon owing to image artifacts, data corruption or data loss, which compromise the potential of multi-modal acquisitions. In this paper, we propose a weakly coupled and geometry co-regularized joint dictionary learning method to address the problem of cross-modality synthesis while considering the fact that collecting the large amounts of training data is often impractical. Our learning stage requires only a few registered multi-modality image pairs as training data. To employ both paired images and a large set of unpaired data, a cross-modality image matching criterion is proposed. Then, we propose a unified model by integrating such a criterion into the joint dictionary learning and the observed common feature space for associating cross-modality data for the purpose of synthesis. Furthermore, two regularization terms are added to construct robust sparse representations. Our experimental results demonstrate superior performance of the proposed model over state-of-the-art methods.

Co-evolution of polygonal and scalloped terrains, southwestern Utopia Planitia, Mars

Science.gov (United States)

Haltigin, T. W.; Pollard, W. H.; Dutilleul, P.; Osinski, G. R.; Koponen, L.

2014-02-01

Thermal contraction crack polygons and scalloped depressions, two of the most common landforms found in Utopia Planitia, Mars, have previously been linked to the presence of ice-rich deposits in the subsurface. Although the formation and evolution of these features individually are relatively well understood, little to no effort has been directed towards elucidating possible interactions that occur between them during their development. Thus, the overarching goal of this research was to investigate if there is an evolutionary link between polygonal and scalloped terrains by correlating metrics representing polygon and scallop maturity. A variety of statistical analyses were performed using HiRISE and MOLA datasets to quantify interactions between four sets of polygonal and scalloped terrains. Our results demonstrate the existence of a negative relationship between polygonal subdivision and surface elevation, indicating that polygon networks become more ‘evolved’ as the surface subsides. These results suggest that the permafrost landscape in Utopia Planitia may once have been extremely ice-rich, and that multiple geomorphic processes may be responsible for its evolution. Ultimately, this work demonstrates that landscape reconstruction is more complete when a system approach is followed, quantifying interactions between landforms as opposed to examining an individual landform in isolation.

LINEAR2007, Linear-Linear Interpolation of ENDF Format Cross-Sections

International Nuclear Information System (INIS)

2007-01-01

1 - Description of program or function: LINEAR converts evaluated cross sections in the ENDF/B format into a tabular form that is subject to linear-linear interpolation in energy and cross section. The code also thins tables of cross sections already in that form. Codes used subsequently need thus to consider only linear-linear data. IAEA1311/15: This version include the updates up to January 30, 2007. Changes in ENDF/B-VII Format and procedures, as well as the evaluations themselves, make it impossible for versions of the ENDF/B pre-processing codes earlier than PREPRO 2007 (2007 Version) to accurately process current ENDF/B-VII evaluations. The present code can handle all existing ENDF/B-VI evaluations through release 8, which will be the last release of ENDF/B-VI. Modifications from previous versions: - Linear VERS. 2007-1 (JAN. 2007): checked against all ENDF/B-VII; increased page size from 60,000 to 600,000 points 2 - Method of solution: Each section of data is considered separately. Each section of File 3, 23, and 27 data consists of a table of cross section versus energy with any of five interpolation laws. LINEAR will replace each section with a new table of energy versus cross section data in which the interpolation law is always linear in energy and cross section. The histogram (constant cross section between two energies) interpolation law is converted to linear-linear by substituting two points for each initial point. The linear-linear is not altered. For the log-linear, linear-log and log- log laws, the cross section data are converted to linear by an interval halving algorithm. Each interval is divided in half until the value at the middle of the interval can be approximated by linear-linear interpolation to within a given accuracy. The LINEAR program uses a multipoint fractional error thinning algorithm to minimize the size of each cross section table

A method for measuring light ion reaction cross-sections

International Nuclear Information System (INIS)

Carlson, R.F.; Ingemarsson, A.; Lantz, M.; Arendse, G.J.; Auce, A.; Cox, A.J.; Foertsch, S.V.; Jacobs, N.M.; Johansson, R.; Nyberg, J.; Peavy, J.; Renberg, P.-U.; Sundberg, O.; Stander, J.A.; Steyn, G.F.; Tibell, G.; Zorro, R.

2005-01-01

An experimental procedure for measuring reaction cross-sections of light ions in the energy range 20-50 MeV/nucleon, using a modified attenuation technique, is described. The detection method incorporates a forward detector that simultaneously measures the reaction cross-sections for five different sizes of the solid angle in steps from 99.1% to 99.8% of the total solid angle. The final reaction cross-section values are obtained by extrapolation to the full solid angle

A method for measuring light ion reaction cross sections

International Nuclear Information System (INIS)

Carlson, R.F.; Ingemarsson, A.; Lantz, M.

2005-03-01

An experimental procedure for measuring reaction cross sections of light ions in the energy range 20-50 MeV/nucleon, using a modified attenuation technique, is described. The detection method incorporates a forward detector that simultaneously measures the reaction cross sections for five different sizes of the solid angles in steps from 99.1 to 99.8% of the total solid angle. The final reaction cross section values are obtained by extrapolation to the full solid angle

Calculated Cross Sections for the Electron Impact Ionization of Molecular Ions

Science.gov (United States)

Deutsch, H.; Becker, K.; Defrance, P.; Onthong, U.; Parajuli, R.; Probst, M.; Matt-Leubner, S.; Maerk, T.

2002-10-01

We report the results of the application of the semi- classical Deutsch-Märk (DM) formalism to the calculation of the absolute electron-impact ionization cross section of the molecular ions H2+, N2+, O2+, CD+, CO+, CO2+, H3O+, and CH4+ for which experimental data have been reported . Where available, we also compare our calculated cross sections with calculated cross sections using the BEB method of Kim and co-workers. The level of agreement between the experimentally determined and calculated cross section is satisfactory in some cases. In all cases, the calculated cross sections exceed the measured cross sections which is not surprising in view of the experimental complications in measuring ionization cross sections of molecular ions due to the presence of competing channels such as ionization dissociative ionization, and dissociative excitation. Work supported in part by FWF, OEAW, and NASA.

Meeting cross-section requirements for nuclear-energy design

Energy Technology Data Exchange (ETDEWEB)

Weisbin, C.R.; de Saussure, G.; Santoro, R.T. (Oak Ridge National Lab., TN (USA)); Gilai, T. (Ben-Gurion Univ. of the Negev, Beersheba (Israel))

1982-01-01

Current requirements in cross-section data that are essential to nuclear-energy programmes are summarized and explained and some insight into how these data might be obtained is provided. The six sections of the paper describe: design parameters and target accuracies; data collection, evaluation and analysis; determination of high-accuracy differential nuclear data for technological applications; status of selected evaluated nuclear data; analysis of benchmark testing; identification of important cross sections and inferred needs.

Neutron Elastic Scattering Cross Sections Experimental Data and Optical Model Cross Section Calculations. A Compilation of Neutron Data from the Studsvik Neutron Physics Laboratory

Energy Technology Data Exchange (ETDEWEB)

Holmqvist, B; Wiedling, T

1969-06-15

Neutron elastic scattering cross section measurements have been going on for a long period at the Studsvik Van de Graaff laboratory. The cross sections of a range of elements have been investigated in the energy interval 1.5 to 8 MeV. The experimental data have been compared with cross sections calculated with the optical model when using a local nuclear potential.

Systematics of fission cross sections at the intermediate energy region

Energy Technology Data Exchange (ETDEWEB)

Fukahori, Tokio; Chiba, Satoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1997-03-01

The systematics was obtained with fitting experimental data for proton induced fission cross sections of Ag, {sup 181}Ta, {sup 197}Au, {sup 206,207,208}Pb, {sup 209}Bi, {sup 232}Th, {sup 233,235,238}U, {sup 237}Np and {sup 239}Pu above 20 MeV. The low energy cross section of actinoid nuclei is omitted from systematics study, since the cross section has a complicated shape and strongly depends on characteristic of nucleus. The fission cross sections calculated by the systematics are in good agreement with experimental data. (author)

Total cross-section measurements progress in nuclear physics

CERN Document Server

Giacomelli, G; Mulvey, J H

2013-01-01

Total Cross-Section Measurements discusses the cross-sectional dimensions of elementary hadron collisions. The main coverage of the book is the resonance and high energy area of the given collision. A section of the book explains in detail the characteristic of a resonance region. Another section is focused on the location of the high energy region of collision. Parts of the book define the meaning of resonance in nuclear physics. Also explained are the measurement of resonance and the identification of the area where the resonance originates. Different experimental methods to measure the tota

Learning of Cross-Sectional Anatomy Using Clay Models

Science.gov (United States)

Oh, Chang-Seok; Kim, Ji-Young; Choe, Yeon Hyeon

2009-01-01

We incorporated clay modeling into gross anatomy and neuro-anatomy courses to help students understand cross-sectional anatomy. By making clay models, cutting them and comparing cut surfaces to CT and MR images, students learned how cross-sectional two-dimensional images were created from three-dimensional structure of human organs. Most students…

Q.C.D. estimates of hadronic cross sections

International Nuclear Information System (INIS)

Navelet, H.; Peschanski, R.

1983-03-01

Estimates for hadron-hadron cross-sections are made using the leading log approximation of Q.C.D. The rise of the total inelastic pp cross-sections at high energy is reproduced, thanks to the competition between the small parton-parton interaction and the large multiplicity of gluons predicted by Q.C.D

Hawaii ESI: INDEX (Index Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains vector polygons representing the boundaries of the U.S. Geological Survey 1:24,000 topographic maps and other map and digital data boundaries...

Measurements of Electron Proton Elastic Cross Sections for 0.4

International Nuclear Information System (INIS)

Christy, M.E.; Abdellah Ahmidouch; Christopher Armstrong; John Arrington; Arshak Asaturyan; Steven Avery; Baker, O.; Douglas Beck; Henk Blok; Bochna, C.W.; Werner Boeglin; Peter Bosted; Maurice Bouwhuis; Herbert Breuer; Brown, D.S.; Antje Bruell; Roger Carlini; Nicholas Chant; Anthony Cochran; Leon Cole; Samuel Danagoulian; Donal Day; James Dunne; Dipangkar Dutta; Rolf Ent; Howard Fenker; Fox, B.; Liping Gan; Haiyan Gao; Kenneth Garrow; David Gaskell; Ashot Gasparian; Don Geesaman; Paul Gueye; Mark Harvey; Roy Holt; Xiaodong Jiang; Cynthia Keppel; Edward Kinney; Yongguang Liang; Wolfgang Lorenzon; Allison Lung; Pete Markowitz; Martin, J.W.; Kevin Mcilhany; David Mckee; David Meekins; Miller, M.A.; Richard Milner; Joseph Mitchell; Hamlet Mkrtchyan; Robert Mueller; Alan Nathan; Gabriel Niculescu; Maria-ioana Niculescu; Thomas O'neill; Vassilios Papavassiliou; Stephen Pate; Rodney Piercey; David Potterveld; Ronald Ransome; Joerg Reinhold; Rollinde, E.; Philip Roos; Adam Sarty; Reyad Sawafta; Elaine Schulte; Edwin Segbefia; Smith, C.; Samuel Stepanyan; Steffen Strauch; Vardan Tadevosyan; Liguang Tang; Raphael Tieulent; Alicia Uzzle; William Vulcan; Stephen Wood; Feng Xiong; Lulin Yuan; Markus Zeier; Benedikt Zihlmann; Vitaliy Ziskin

2004-01-01

We report on precision measurements of the elastic cross section for electron-proton scattering performed in Hall C at Jefferson Lab. The measurements were made at 28 distinct kinematic settings covering a range in momentum transfer of 0.4 < Q2 < 5.5 (GeV/c)2. These measurements represent a significant contribution to the world's cross section data set in the Q2 range, where a large discrepancy currently exists between the ratio of electric to magnetic proton form factors extracted from previous cross section measurements and that recently measured via polarization transfer in Hall A at Jefferson Lab. This data set shows good agreement with previous cross section measurements, indicating that if a heretofore unknown systematic error does exist in the cross section measurements, then it is intrinsic to all such measurements

Electron capture cross sections by O+ from atomic He

International Nuclear Information System (INIS)

Joseph, Dwayne C; Saha, Bidhan C

2009-01-01

The adiabatic representation is used in both the quantal and semi classical molecular orbital close coupling methods (MOCC) to evaluate charge exchange cross sections. Our results show good agreement with experimental cross sections

Electron capture cross sections by O+ from atomic He

Science.gov (United States)

Joseph, Dwayne C.; Saha, Bidhan C.

2009-11-01

The adiabatic representation is used in both the quantal and semi classical molecular orbital close coupling methods (MOCC) to evaluate charge exchange cross sections. Our results show good agreement with experimental cross sections

Photoproton cross section for /sup 19/F

Energy Technology Data Exchange (ETDEWEB)

Tsubota, H [Tohoku Univ., Sendai (Japan). Coll. of General Education; Kawamura, N; Oikawa, S; Uegaki, J I

1975-02-01

Proton energy spectra have been measured at 90/sup 0/ for the /sup 19/F(e,e'p)/sup 18/O reaction in the giant resonance region. The (..gamma..,p/sub 0/) and (..gamma..,p/sub 1/) differential cross sections are extracted from the proton energy spectra by using virtual-photon spectra. The integrated differential cross section of the (..gamma..,p/sub 0/) and (..gamma..,p/sub 1/) reactions are 1.80+-0.27 and 0.50+-0.45 MeV-mb/sr, respectively. The results are discussed with the shell model theory by comparing with the (..gamma..,p/sub 0/) cross section of the neighboring 4n-nucleus /sup 20/Ne. A significant increase of the proton yield leaving the non-ground states is found at 25 MeV of the incident electron energy. This is discussed in terms of the core excitation effect.

Electron-collision cross sections for iodine

International Nuclear Information System (INIS)

Zatsarinny, O.; Bartschat, K.; Garcia, G.; Blanco, F.; Hargreaves, L.R.; Jones, D.B.; Murrie, R.; Brunton, J.R.; Brunger, M.J.; Hoshino, M.; Buckman, S.J.

2011-01-01

We present results from a joint experimental and theoretical study of elastic electron scattering from atomic iodine. The experimental results were obtained by subtracting known cross sections from the measured data obtained with a pyrolyzed mixed beam containing a variety of atomic and molecular species. The calculations were performed using both a fully relativistic Dirac B-spline R-matrix (close-coupling) method and an optical model potential approach. Given the difficulty of the problem, the agreement between the two sets of theoretical predictions and the experimental data for the angle-differential and the angle-integrated elastic cross sections at 40 eV and 50 eV is satisfactory.

Fission neutron spectrum averaged cross sections for threshold reactions on arsenic

International Nuclear Information System (INIS)

Dorval, E.L.; Arribere, M.A.; Kestelman, A.J.; Comision Nacional de Energia Atomica, Cuyo Nacional Univ., Bariloche; Ribeiro Guevara, S.; Cohen, I.M.; Ohaco, R.A.; Segovia, M.S.; Yunes, A.N.; Arrondo, M.; Comision Nacional de Energia Atomica, Buenos Aires

2006-01-01

We have measured the cross sections, averaged over a 235 U fission neutron spectrum, for the two high threshold reactions: 75 As(n,p) 75 mGe and 75 As(n,2n) 74 As. The measured averaged cross sections are 0.292±0.022 mb, referred to the 3.95±0.20 mb standard for the 27 Al(n,p) 27 Mg averaged cross section, and 0.371±0.032 mb referred to the 111±3 mb standard for the 58 Ni(n,p) 58m+g Co averaged cross section, respectively. The measured averaged cross sections were also evaluated semi-empirically by numerically integrating experimental differential cross section data extracted for both reactions from the current literature. The calculations were performed for four different representations of the thermal-neutron-induced 235 U fission neutron spectrum. The calculated cross sections, though depending on analytical representation of the flux, agree with the measured values within the estimated uncertainties. (author)

Precise measurements of neutron capture cross sections for FP

International Nuclear Information System (INIS)

Nakamura, Shoji; Harada, Hideo; Katoh, Toshio

2000-01-01

The thermal neutron capture cross sections (σ 0 ) and the resonance integrals (I 0 ) of some fission products (FP), such as 137 Cs, 90 Sr, 99 Tc, 129 I and 135 Cs, were measured by the activation and γ-ray spectroscopic methods. Moreover, the cross section measurements were done for other FP elements, such as 127 I, 133 Cs and 134 Cs. This paper provides the summary of the FP cross section measurements, which have been performed by authors. (author)

Habit, Production, and the Cross-Section of Stock Returns

OpenAIRE

Chen, Andrew Y.

2014-01-01

Solutions to the equity premium puzzle should inform us about the cross-section of stock returns. An external habit model with heterogeneous firms reproduces numerous stylized facts about both the equity premium and the value premium. The equity premium is large, time-varying, and linked with consumption volatility. The cross-section of expected returns is log-linear in B/M, and the slope matches the data. The explanation for the value premium lies in the interaction between the cross-section...

Drell-Yan cross section in the jet calculus scheme

International Nuclear Information System (INIS)

Tanaka, Hidekazu; Kobayashi, Hirokazu

2009-01-01

We calculate factorized cross sections for lepton pair production mediated by a virtual photon in hadron-hadron collisions using the jet calculus scheme, in which a kinematical constraint due to parton radiation is taken into account. This method guarantees a proper phase space boundary for subtraction terms. Some properties of the calculated cross sections are examined. We also discuss matching between the hard scattering cross sections and parton showers at the next-to-leading logarithmic (NLL) order of quantum chromodynamics (QCD). (author)

Testing of cross section libraries for TRIGA criticality benchmark

International Nuclear Information System (INIS)

Snoj, L.; Trkov, A.; Ravnik, M.

2007-01-01

Influence of various up-to-date cross section libraries on the multiplication factor of TRIGA benchmark as well as the influence of fuel composition on the multiplication factor of the system composed of various types of TRIGA fuel elements was investigated. It was observed that keff calculated by using the ENDF/B VII cross section library is systematically higher than using the ENDF/B-VI cross section library. The main contributions (∼ 2 20 pcm) are from 235 U and Zr. (author)

Cross-section sensitivity analyses for a Tokamak Experimental Power Reactor

International Nuclear Information System (INIS)

Simmons, E.L.; Gerstl, S.A.W.; Dudziak, D.J.

1977-09-01

The objectives of this report were (1) to determine the sensitivity of neutronic responses in the preliminary design of the Tokamak Experimental Power Reactor by Argonne National Laboratory, and (2) to develop the use of a neutron-gamma coupled cross-section set in the calculation of cross-section sensitivity analysis. Response functions such as neutron plus gamma kerma, Mylar dose, copper transmutation, copper dpa, and activation of the toroidal field coil dewar were investigated. Calculations revealed that the responses were most sensitive to the high-energy group cross sections of iron in the innermost regions containing stainless steel. For example, both the neutron heating of the toroidal field coil and the activation of the toroidal field coil dewar show an integral sensitivity of about -5 with respect to the iron total cross sections. Major contributors are the scattering cross sections of iron, with -2.7 and -4.4 for neutron heating and activation, respectively. The effects of changes in gamma cross sections were generally an order of 10 lower

Decompositions, partitions, and coverings with convex polygons and pseudo-triangles

NARCIS (Netherlands)

Aichholzer, O.; Huemer, C.; Kappes, S.; Speckmann, B.; Tóth, Cs.D.

2007-01-01

We propose a novel subdivision of the plane that consists of both convex polygons and pseudo-triangles. This pseudo-convex decomposition is significantly sparser than either convex decompositions or pseudo-triangulations for planar point sets and simple polygons. We also introduce pseudo-convex

Evaluation of covariance for 238U cross sections

International Nuclear Information System (INIS)

Kawano, Toshihiko; Nakamura, Masahiro; Matsuda, Nobuyuki; Kanda, Yukinori

1995-01-01

Covariances of 238 U are generated using analytic functions for representation of the cross sections. The covariances of the (n,2n) and (n,3n) reactions are derived with a spline function, while the covariances of the total and the inelastic scattering cross section are estimated with a linearized nuclear model calculation. (author)

Implementation of the rapid cross section adjustment approach at General Electric

International Nuclear Information System (INIS)

Cowan, C.L.; Kujawski, E.; Protsik, R.

1978-01-01

The General Electric rapid cross section adjustment approach was developed to use the shielding factor method for formulating multigroup cross sections. In this approach, space- and composition-dependent cross sections for a particular reactor or shield design are prepared from a generalized cross section library by the use of resonance self-shielding factors, and by the adjustment of elastic scattering cross sections for the local neutron flux spectra. The principal tool in the cross section adjustment package is the data processing code TDOWN. This code was specified to give the user a high degree of flexibility in the analysis of advanced reactor designs. Of particular interest in the analysis of critical experiments is the ability to carry out cell heterogeneity self-shielding calculations using a multiregion equivalence relationship, and the homogenization of the cross sections over the specified cell with the flux weighting obtained from transport theory calculations. Extensive testing of the rapid cross section adjustment approach, including comparisons with Monte Carlo methods, indicated that this approach can be utilized with a high degree of confidence in the design analysis of complex fast reactor systems. 2 figures, 1 table

Application of Littlewood-Paley decomposition to the regularity of Boltzmann type kinetic equations

International Nuclear Information System (INIS)

EL Safadi, M.

2007-03-01

We study the regularity of kinetic equations of Boltzmann type.We use essentially Littlewood-Paley method from harmonic analysis, consisting mainly in working with dyadics annulus. We shall mainly concern with the homogeneous case, where the solution f(t,x,v) depends only on the time t and on the velocities v, while working with realistic and singular cross-sections (non cutoff). In the first part, we study the particular case of Maxwellian molecules. Under this hypothesis, the structure of the Boltzmann operator and his Fourier transform write in a simple form. We show a global C ∞ regularity. Then, we deal with the case of general cross-sections with 'hard potential'. We are interested in the Landau equation which is limit equation to the Boltzmann equation, taking in account grazing collisions. We prove that any weak solution belongs to Schwartz space S. We demonstrate also a similar regularity for the case of Boltzmann equation. Let us note that our method applies directly for all dimensions, and proofs are often simpler compared to other previous ones. Finally, we finish with Boltzmann-Dirac equation. In particular, we adapt the result of regularity obtained in Alexandre, Desvillettes, Wennberg and Villani work, using the dissipation rate connected with Boltzmann-Dirac equation. (author)

Reference Cross Sections for Charged-particle Monitor Reactions

Science.gov (United States)

Hermanne, A.; Ignatyuk, A. V.; Capote, R.; Carlson, B. V.; Engle, J. W.; Kellett, M. A.; Kibédi, T.; Kim, G.; Kondev, F. G.; Hussain, M.; Lebeda, O.; Luca, A.; Nagai, Y.; Naik, H.; Nichols, A. L.; Nortier, F. M.; Suryanarayana, S. V.; Takács, S.; Tárkányi, F. T.; Verpelli, M.

2018-02-01

Evaluated cross sections of beam-monitor reactions are expected to become the de-facto standard for cross-section measurements that are performed over a very broad energy range in accelerators in order to produce particular radionuclides for industrial and medical applications. The requirements for such data need to be addressed in a timely manner, and therefore an IAEA coordinated research project was launched in December 2012 to establish or improve the nuclear data required to characterise charged-particle monitor reactions. An international team was assembled to recommend more accurate cross-section data over a wide range of targets and projectiles, undertaken in conjunction with a limited number of measurements and more extensive evaluations of the decay data of specific radionuclides. Least-square evaluations of monitor-reaction cross sections including uncertainty quantification have been undertaken for charged-particle beams of protons, deuterons, 3He- and 4He-particles. Recommended beam monitor reaction data with their uncertainties are available at the IAEA-NDS medical portal http://www-nds.iaea.org/medical/monitor_reactions.html.

Total and partial recombination cross sections for F6+

International Nuclear Information System (INIS)

Mitnik, D.M.; Pindzola, M.S.; Badnell, N.R.

1999-01-01

Total and partial recombination cross sections for F 6+ are calculated using close-coupling and distorted-wave theory. For total cross sections, close-coupling and distorted-wave results, which include interference between the radiative and dielectronic pathways, are found to be in good agreement with distorted-wave results based on a sum of independent processes. Total cross sections near zero energy are dominated by contributions from low-energy dielectronic recombination resonances. For partial cross sections, the close-coupling and distorted-wave theories predict strong interference for recombination into the final recombined ground state 1s 2 2s 21 S 0 of F 5+ , but only weak interference for recombination into the levels of the 1s 2 2s2p configuration. copyright 1999 The American Physical Society

Absolute cross-section measurements of inner-shell ionization

Science.gov (United States)

Schneider, Hans; Tobehn, Ingo; Ebel, Frank; Hippler, Rainer

1994-12-01

Cross section ratios for K- and L-shell ionization of thin silver and gold targets by positron and electron impact have been determined at projectile energies of 30 70 keV. The experimental results are confirmed by calculations in plane wave Born approximation (PWBA) which include an electron exchange term and account for the deceleration or acceleration of the incident projectile in the nuclear field of the target atom. We report first absolute cross sections for K- and L-shell ionization of silver and gold targets by lepton impact in the threshold region. We have measured the corresponding cross sections for electron (e-) impact with an electron gun and the same experimental set-up.

Automated Cross-Sectional Measurement Method of Intracranial Dural Venous Sinuses.

Science.gov (United States)

Lublinsky, S; Friedman, A; Kesler, A; Zur, D; Anconina, R; Shelef, I

2016-03-01

MRV is an important blood vessel imaging and diagnostic tool for the evaluation of stenosis, occlusions, or aneurysms. However, an accurate image-processing tool for vessel comparison is unavailable. The purpose of this study was to develop and test an automated technique for vessel cross-sectional analysis. An algorithm for vessel cross-sectional analysis was developed that included 7 main steps: 1) image registration, 2) masking, 3) segmentation, 4) skeletonization, 5) cross-sectional planes, 6) clustering, and 7) cross-sectional analysis. Phantom models were used to validate the technique. The method was also tested on a control subject and a patient with idiopathic intracranial hypertension (4 large sinuses tested: right and left transverse sinuses, superior sagittal sinus, and straight sinus). The cross-sectional area and shape measurements were evaluated before and after lumbar puncture in patients with idiopathic intracranial hypertension. The vessel-analysis algorithm had a high degree of stability with <3% of cross-sections manually corrected. All investigated principal cranial blood sinuses had a significant cross-sectional area increase after lumbar puncture (P ≤ .05). The average triangularity of the transverse sinuses was increased, and the mean circularity of the sinuses was decreased by 6% ± 12% after lumbar puncture. Comparison of phantom and real data showed that all computed errors were <1 voxel unit, which confirmed that the method provided a very accurate solution. In this article, we present a novel automated imaging method for cross-sectional vessels analysis. The method can provide an efficient quantitative detection of abnormalities in the dural sinuses. © 2016 by American Journal of Neuroradiology.

From ZZ to ZH: How Low Can These Cross Sections Go or Everybody, Let's Cross Section Limbo

International Nuclear Information System (INIS)

Strauss, Emanuel Alexandre

2009-01-01

We report on two searches performed at the D0 detector at the Fermi National Laboratory. The first is a search for Z di-boson production with a theoretical cross section of 1.4 pb. The search was performed on 2.6 fb -1 of data and contributed to the first observation of ZZ production at a hadron collider. The second is a search for a low mass Standard Model Higgs in 4.2 fb -1 of data. The Higgs boson is produced in association with a Z boson where the Higgs decays hadronically and the Z decays to two leptons. The ZZ search was performed in both the di-electron and di-muon channels. For the ZH search, we will focus on the muonic decays where we expanded the traditional coverage by considering events in which one of the two muons fails the selection requirement, and is instead reconstructed as an isolated track. We consider Higgs masses between 100 and 150 GeV, with theoretical cross sections ranging from 0.17 to 0.042 pb, and set upper limits on the ZH production cross-section at 95% confidence level

137Cs in Research Polygon 'Sumbar'

International Nuclear Information System (INIS)

Skoko, B.; Marovic, G.; Babic, D.; Vickovic, I.

2011-01-01

In 2009, Radiation Protection Unit of the Institute for Medical Reseach and Occupational Health started a radioactivity measurement programme in research polygon ''Sumbar''. The purpose of these investigations is to collect as many data as possible about the contamination of the polygon that is mainly covered by a forest of English oak (Quercus robur) and hornbeam (Carpinus betulus). Once contaminated, forests represent long-term sources of radiation exposure to specific population groups which are using them as a source of foodstuffs. After the Chernobyl accident, researchers have shown that there has been more variability in radionuclide activity concentration in forests than in agricultural ecosystems. In order to carry out a radioactivity screening of the polygon, we randomly chosed three sampling sites for collecting soil, grass and moss samples. Different species of mushrooms were collected over the whole polygon area. The average activity concentration of 137Cs in soil for two sampling sites is (123 @ 9) Bq kg -1 , while the result for the third site is lower by an order of magnitude ((16.1@0.5) Bq kg -1 ). The activity concentration of 137Cs in grass samples ranges from (0.43 @ 0.03) Bq kg -1 to (13.2 @ 0.1) Bq kg -1 , and in moss samples from (8.7 @ 0.2) Bq kg -1 to (57.8 @ 0.3) Bq kg - 1. In five collected mushroom species, the activity of 137Cs is in the range between (4.1 @ 0.5) Bq kg -1 and (610 @ 5) Bq kg -1 , the lowest and the highest values referreing to Clitocybe nebularis and Gymnopus dryophilus, respectively. Parasitic mushrooms exhibit activity below the minimum detection level. Our preliminary results show and confirm variability of the activity concentration of 137Cs in different parts of this ecosystem. (author)

System and method for the adaptive mapping of matrix data to sets of polygons

Science.gov (United States)

Burdon, David (Inventor)

2003-01-01

A system and method for converting bitmapped data, for example, weather data or thermal imaging data, to polygons is disclosed. The conversion of the data into polygons creates smaller data files. The invention is adaptive in that it allows for a variable degree of fidelity of the polygons. Matrix data is obtained. A color value is obtained. The color value is a variable used in the creation of the polygons. A list of cells to check is determined based on the color value. The list of cells to check is examined in order to determine a boundary list. The boundary list is then examined to determine vertices. The determination of the vertices is based on a prescribed maximum distance. When drawn, the ordered list of vertices create polygons which depict the cell data. The data files which include the vertices for the polygons are much smaller than the corresponding cell data files. The fidelity of the polygon representation can be adjusted by repeating the logic with varying fidelity values to achieve a given maximum file size or a maximum number of vertices per polygon.