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.

scholarly journals Buckling analysis of tape springs using a rod model with flexible cross-sections

2012 ◽  
Author(s):  
Stéphane Bourgeois ◽  
Bruno Cochelin ◽  
François Guinot ◽  
Elia Picault
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Buckling Analysis ◽  
Rod Model ◽  
The Creation ◽  
The Cross

This work is devoted to the study of tape springs behaviour. We focus on the instabilities that lead to the creation of localised folds, due to the flattening of the cross-section. Depending on the kind of loading, the folds can move along the tape, split or disappear. Using an extended four parameters rod model with flexible cross-sections, we study several modes of instabilities (number and localisation of folds) for such structures submitted to an overall compression or bending.

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.

Experimental Studies Of Multilayer Glass Structures On Compression, Compression With Bending And Simple Bending

2019 ◽  
pp. 22-30
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Applied Load ◽  
Experimental Studies ◽  
Strength Properties ◽  
Research Topic ◽  
Normative Values ◽  
Laminated Glass ◽  
The Cross ◽  
Experimental Values

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.

scholarly journals Total cross sections of eγ → $$ eX\overline{X} $$ processes with X = μ, γ, e via multiloop methods

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Roman N. Lee ◽  
Alexey A. Lyubyakin ◽  
Vyacheslav A. Stotsky
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Elliptic Integral ◽  
High Energy ◽  
Calculation Methods ◽  
Complete Elliptic Integral ◽  
Total Cross Sections ◽  
Multiloop Calculation ◽  
The Cross ◽  
Analytical Expressions

Abstract Using modern multiloop calculation methods, we derive the analytical expressions for the total cross sections of the processes e−γ →$$ {e}^{-}X\overline{X} $$ e − X X ¯ with X = μ, γ or e at arbitrary energies. For the first two processes our results are expressed via classical polylogarithms. The cross section of e−γ → e−e−e+ is represented as a one-fold integral of complete elliptic integral K and logarithms. Using our results, we calculate the threshold and high-energy asymptotics and compare them with available results.

scholarly journals Asymptotic Behavior of Stable Structures Made of Beams

2021 ◽  
Author(s):  
Georges Griso ◽  
Larysa Khilkova ◽  
Julia Orlik ◽  
Olena Sivak
Keyword(s):  
Asymptotic Behavior ◽  
Cross Section ◽  
Cross Sections ◽  
Linear Elasticity ◽  
Circular Cross Section ◽  
Linear Elasticity Theory ◽  
Linear Elastic ◽  
The Cross ◽  
Small Rotation ◽  
Stable Structures

AbstractIn this paper, we study the asymptotic behavior of an $\varepsilon $ ε -periodic 3D stable structure made of beams of circular cross-section of radius $r$ r when the periodicity parameter $\varepsilon $ ε and the ratio ${r/\varepsilon }$ r / ε simultaneously tend to 0. The analysis is performed within the frame of linear elasticity theory and it is based on the known decomposition of the beam displacements into a beam centerline displacement, a small rotation of the cross-sections and a warping (the deformation of the cross-sections). This decomposition allows to obtain Korn type inequalities. We introduce two unfolding operators, one for the homogenization of the set of beam centerlines and another for the dimension reduction of the beams. The limit homogenized problem is still a linear elastic, second order PDE.

ISOSPIN DECOMPOSITION OF pp → NNππ CROSS SECTIONS — DO WE SEE A SIGN OF Δ(1600) EXCITATION IN THE nnπ+π+ CHANNEL?

2009 ◽  
Vol 24 (02n03) ◽  
pp. 450-453
Author(s):  
◽  
T. SKORODKO ◽  
M. BASHKANOV ◽  
D. BOGOSLOWSKY ◽  
H. CALÉN ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Pion Production ◽  
Significant Contribution ◽  
Differential Cross Sections ◽  
Pp Collisions ◽  
Theoretical Predictions ◽  
Order Of Magnitude ◽  
The Cross

The two-pion production in pp-collisions has been investigated in exclusive measurements from threshold up to Tp = 1.36 GeV . Total and differential cross sections have been obtained for the channels pnπ+π0, ppπ+π-, ppπ0π0 and also nnπ+π+. For intermediate incident energies Tp > 1 GeV , i.e. in the region, which is beyond the Roper excitation but at the onset of ΔΔ excitation the total ppπ0π0 cross section falls behind theoretical predictions by as much as an order of magnitude near 1.2 GeV, whereas the nnπ+π+ cross section is a factor of five larger than predicted. A model-unconstrained isospin decompostion of the cross section points to a significant contribution of an isospin 3/2 resonance other than the Δ(1232). As a possible candidate the Δ(1600) is discussed.

scholarly journals The Cross Section for the J = 0 → 2 Rotational Excitation of Hydrogen by Slow Electrons

1969 ◽  
Vol 22 (6) ◽  
pp. 715 ◽  
Author(s):  
RW Crompton ◽  
DK Gibson ◽  
AI McIntosh
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Vibrational Excitation ◽  
The Cross ◽  
Excitation Processes ◽  
Slow Electrons ◽  
And Diffusion ◽  
Momentum Transfer Cross Section ◽  
Section Analysis

The results of electron drift and diffusion measurements in parahydrogen have been analysed to determine the cross sections for momentum transfer and for rotational and vibrational excitation. The limited number of possible excitation processes in parahydrogen and the wide separation of the thresholds for these processes make it possible to determine uniquely the J = 0 → 2 rotational cross section from threshold to 0.3 eV. In addition, the momentum transfer cross section has been determined for energies less than 2 eV and it is shown that, near threshold, a vibrational cross section compatible with the data must lie within relatively narrow limits. The problems of uniqueness and accuracy inherent in the swarm method of cross section analysis are discussed. The present results are compared with other recent theoretical and experimental determinations; the agreement with the most recent calculations of Henry and Lane is excellent.

Thermo-structural analysis of a honeycomb-type volumetric absorber for concentrated solar power applications

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Masoud Behzad ◽  
Benjamin Herrmann ◽  
Williams R. Calderón-Muñoz ◽  
José M. Cardemil ◽  
Rodrigo Barraza
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Steady State ◽  
Discrete Model ◽  
Continuum Model ◽  
Transient State ◽  
Operating Conditions ◽  
Steady State Condition ◽  
Content Type ◽  
The Continuum

Purpose Volumetric air receivers experience high thermal stress as a consequence of the intense radiation flux they are exposed to when used for heat and/or power generation. This study aims to propose a proper design that is required for the absorber and its holder to ensure efficient heat transfer between the fluid and solid phases and to avoid system failure due to thermal stress. Design/methodology/approach The design and modeling processes are applied to both the absorber and its holder. A multi-channel explicit geometry design and a discrete model is applied to the absorber to investigate the conjugate heat transfer and thermo-mechanical stress levels present in the steady-state condition. The discrete model is used to calibrate the initial state of the continuum model that is then used to investigate the transient operating states representing cloud-passing events. Findings The steady-state results constitute promising findings for operating the system at the desired airflow temperature of 700°C. In addition, we identified regions with high temperatures and high-stress values. Furthermore, the transient state model is capable of capturing the heat transfer and fluid dynamics phenomena, allowing the boundaries to be checked under normal operating conditions. Originality/value Thermal stress analysis of the absorber and the steady/transient-state thermal analysis of the absorber/holder were conducted. Steady-state heat transfer in the explicit model was used to calibrate the initial steady-state of the continuum model.

scholarly journals Supplemental Material: Plate boundary trench retreat and dextral shear drive intracontinental fault-slip histories: Neogene dextral faulting across the Gabbs Valley and Gillis Ranges, Central Walker Lane, Nevada

2020 ◽  
Author(s):  
J. Lee ◽  
et al.
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Plate Boundary ◽  
Fault Slip ◽  
Cross Sectional ◽  
Walker Lane ◽  
Dextral Shear ◽  
The Cross

<div>Figure 6. Interpretative cross sections illustrating the cross-sectional geometry of several paleovalleys. See Figure 3 for location of all cross sections and Figure 8 for location of cross section CCʹ. Cross sections AAʹ and BBʹ are plotted at the same scale, and cross section CCʹ is plotted at a smaller scale. Figure 6 is intended to be viewed at a width of 45.1 cm.</div>

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