scholarly journals Cross section of curvature radiation absorption

2018 ◽  
Vol 617 ◽  
pp. A84 ◽  
Author(s):  
Nicola Locatelli ◽  
Gabriele Ghisellini
Keyword(s):  
Cross Section ◽  
Emission Angle ◽  
Point Of View ◽  
Stimulated Emission ◽  
Radiation Absorption ◽  
Radio Bursts ◽  
Brightness Temperatures ◽  
Curvature Radiation ◽  
Absorption Of Light ◽  
The Cross

When treating the absorption of light, it is instructive to focus on the absorption coefficient related to the probability of photons to survive while traversing a layer of material. From the point of view of particles doing the absorption, however, the elementary interaction of the particle with the photon is best described by the corresponding cross section. We revisit curvature radiation in order to find the absorption cross section for this process, making use of the Einstein coefficients and their relations with spontaneous and stimulated emission and true absorption. We derive the cross section as a function of the emission angle ψ (i.e. the angle between the instantaneous velocity vector and the direction of the photon) and the cross section integrated over angles. Both are positive, contrary to the synchrotron case for which the cross section can be negative for large ψ. Therefore, it is impossible to have curvature radiation masers. This has important consequences for sources of very large brightness temperatures that require a coherent emission process, such as pulsars and fast radio bursts.

Semicrystalline Structure and Mechanical Properties of Polyolefin-Based Materials

2012 ◽  
Vol 441 ◽  
pp. 713-716
Author(s):  
Mizue Kuriyagawa ◽  
Koh Hei Nitta
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Draw Ratio ◽  
Structural Model ◽  
Point Of View ◽  
Cross Sectional ◽  
Molecular Weights ◽  
The Cross ◽  
Sectional Shape ◽  
Structural Point

The mechanical yielding and necking behaviors of metallocene-catalyzed high density polyethylenes were investigated from a structural point of view. In particular the natural draw ratio was investigated with different crosshead speeds, molecular weights, and the cross-section shapes of sample specimens. We proposed a structural model for explaining the necking formation in addition to the molecular weight and the cross-sectional shape dependences of the natural draw ratio.

Notes on the Kinematics of an Octopus’s Arm

2008 ◽  
Author(s):  
Y. Levinson ◽  
R. Segev ◽  
A. Shapiro
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Discrete Model ◽  
Continuum Model ◽  
Plane Deformation ◽  
Point Of View ◽  
Parallel Mechanisms ◽  
Rod Model ◽  
The Cross ◽  
The Continuum

In a study of the kinematics of an Octopus’s arm from the robotics point of view, we consider two models: a discrete model and a continuum model. Both models represent control of the curve in space defined by the centerline of the arm and the position of the suction elements of the arm relative to the centerline. The two models also represent the control of the arm by means of three groups of muscles: the longitudinal, transverse and helicoidal groups. Another feature of the kinematics exhibited by the two models is the use of incompressibility in the control of the arm. In the discrete model, the arm is represented as a sequence of parallel mechanisms. Each mechanism in the sequence consists of two parallel platforms of variable dimensions so that the resulting sequence of platforms represents the various cross sections of the arm. The continuum rod model that we use allows linear in-plane deformation of the cross-section and assumes that cross-sections remain perpendicular to the axis of the rod.

THE PHOTONEUTRON CROSS SECTIONS FOR THE REACTIONS Br81 (γ,n) Br80 AND Br81 (γ,n) Br80* AND AN ANALYSIS OF THE RATIO BETWEEN THESE CROSS SECTIONS

1952 ◽  
Vol 30 (5) ◽  
pp. 476-487 ◽  
Author(s):  
L. Katz ◽  
L. Pease ◽  
H. Moody
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Point Of View ◽  
Photonuclear Reactions ◽  
Shape Characteristic ◽  
Elementary Analysis ◽  
Different Types ◽  
The Cross

Cross-section curves have been measured as a function of energy for the reactions Br81(γ,n)Br80 and Br81(γ,n)Br80* and the ratio between these cross sections has been examined critically. The curves exhibit the peaked shape characteristic of photonuclear reactions with maximum cross sections of 88 and 42 millibarns respectively. It is shown that the ratio of the cross sections depends on the spins of the excited levels in which the Br80 nucleus is left prior to γ cascading and thus on the reaction leading to it. An elementary analysis based on this point of view gives results consistent with the ratio measured for six different types of reactions.

THE STUDY OF ORE BREAKAGE IN BALL MILL TO ASSESS THE ENERGY EFFICIENCY OF ITS GRINDING

2021 ◽  
Author(s):  
Vasyl Kondratets ◽  
◽  
Anatolii Matsui. ◽  
Andrii Pikilniak ◽  
Anatolii Artiukhov ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Cross Section ◽  
Cross Sections ◽  
Elastic Element ◽  
Ball Mill ◽  
Point Of View ◽  
Average Value ◽  
Average Deformation ◽  
The Cross ◽  
Elastic Elements

The results of mathematical modelling of ore breakage by a ball mill based on mathematical models of loaded and unloaded elastic elements are presented. The property of the arrangement of balls in the drum due to segregation is used, under the influence of which they are distributed with increasing size from the loading to the unloading throat, and in the cross-sections from the lining to the axis. It is shown that it is advisable to use the balls in the cross-section of the drum, where their size is 50 mm. The more the volume of ore is destroyed, the more the ball's energy is spent on this, the less energy will be converted into deformation of the elastic element. Consequently, the value of the deformation of the elastic element corresponds to the volume of the destroyed ore, as well as the energy efficiency of its grinding. The approach of interaction of balls with an elastic element from the point of view of mass phenomena will be more effective. The average value of deformations by all balls that have passed through the elastic element, arbitrarily accurately characterizes the average value of the destroyed volume of ore, that is, the energy efficiency of its grinding. The controlled parameter is found in accordance with the proposed relationship with the measured average deformation value of the elastic element. The deviation of certain values from the reference values is within 1%, which meets the requirements of the technological process.

A New Approach to the Demonstration of Oxidase-Localization Using Tannic Acid Or Catechin

1973 ◽  
Vol 31 ◽  
pp. 698-699
Author(s):  
V. Mizuhira ◽  
Y. Futaesaku
Keyword(s):  
Cross Section ◽  
Tannic Acid ◽  
Elastic Fiber ◽  
The Other ◽  
New Approach ◽  
Tissue Block ◽  
Active Reaction ◽  
The Cross

Previously we reported that tannic acid is a very effective fixative for proteins including polypeptides. Especially, in the cross section of microtubules, thirteen submits in A-tubule and eleven in B-tubule could be observed very clearly. An elastic fiber could be demonstrated very clearly, as an electron opaque, homogeneous fiber. However, tannic acid did not penetrate into the deep portion of the tissue-block. So we tried Catechin. This shows almost the same chemical natures as that of proteins, as tannic acid. Moreover, we thought that catechin should have two active-reaction sites, one is phenol,and the other is catechole. Catechole site should react with osmium, to make Os- black. Phenol-site should react with peroxidase existing perhydroxide.

Energy Distribution in Electron Beams

1972 ◽  
Vol 30 ◽  
pp. 568-569
Author(s):  
Tamotsu Ohno
Keyword(s):  
Electron Beam ◽  
Energy Distribution ◽  
Cross Section ◽  
Integral Curve ◽  
Electron Beams ◽  
Electron Gun ◽  
Angular Divergence ◽  
Apparent Increase ◽  
Integral Width ◽  
The Cross

The energy distribution in an electron; beam from an electron gun provided with a biased Wehnelt cylinder was measured by a retarding potential analyser. All the measurements were carried out with a beam of small angular divergence (<3xl0-4 rad) to eliminate the apparent increase of energy width as pointed out by Ichinokawa.The cross section of the beam from a gun with a tungsten hairpin cathode varies as shown in Fig.1a with the bias voltage Vg. The central part of the beam was analysed. An example of the integral curve as well as the energy spectrum is shown in Fig.2. The integral width of the spectrum ΔEi varies with Vg as shown in Fig.1b The width ΔEi is smaller than the Maxwellian width near the cut-off. As |Vg| is decreased, ΔEi increases beyond the Maxwellian width, reaches a maximum and then decreases. Note that the cross section of the beam enlarges with decreasing |Vg|.

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