scholarly journals Snapping of a Planar Elastica With Fixed End Slopes

2008 ◽  
Vol 75 (4) ◽  
Author(s):  
Jen-San Chen ◽  
Yong-Zhi Lin
Keyword(s):  
Theoretical Prediction ◽  
Static Load ◽  
Natural Frequencies ◽  
Equilibrium Configuration ◽  
The Other ◽  
Deflection Curve ◽  
Slope Difference ◽  
The Stability ◽  
Fixed End ◽  
Load Deflection Curve

In this paper, we study the deformation and stability of a planar elastica. One end of the elastica is clamped and fixed in space. The other end of the elastica is also clamped, but the clamp itself is allowed to slide along a linear track with a slope different from that of the fixed clamp. The elastica deforms after it is subjected to an external pushing force on the moving clamp. It is observed that when the pushing force reaches a critical value, snapping may occur as the elastica jumps from one configuration to another remotely away from the original one. In the theoretical investigation, we calculate the static load-deflection curve for a specified slope difference between the fixed clamp and the moving clamp. To study the stability of the equilibrium configuration, we superpose the equilibrium configuration with a small perturbation and calculate the natural frequencies of the deformed elastica. An experimental setup is designed to measure the load-deflection curve and the natural frequencies of the elastica. The measured load-deflection relation agrees with the theoretical prediction very well. On the other hand, the measured natural frequencies do not agree very well with the theoretical prediction, unless the mass of the moving clamp is taken into account.

Resilient Railpads: Their Dynamic Behaviour in the Laboratory and on Track

1989 ◽  
Vol 203 (1) ◽  
pp. 25-32 ◽  
Author(s):  
S L Grassie
Keyword(s):  
Impact Test ◽  
Dynamic Behaviour ◽  
Static Load ◽  
Dynamic Stiffness ◽  
Dynamic Loads ◽  
Dynamic Strain ◽  
Deflection Curve ◽  
Surface Profiling ◽  
Effective Dynamic ◽  
Load Deflection Curve

Resilient railpads in a variety of materials and with different surface profiling have been tested in the laboratory and in track. A laboratory impact test based on that initially developed at the Battelle Columbus Laboratories provides a reliable ranking of the extent to which railpads attenuate dynamic strain in concrete sleepers in track. The test is also a good indication of the average attenuation provided by a pad in track. If dynamic loads in track are particularly severe the fractional attenuation provided by a pad is greater than that indicated by the laboratory impact test. Laboratory resonance apparatus, in which the pad is the principal resilient element in a simple dynamic system, has been made to find the railpad's effective dynamic stiffness. There is good correlation between the stiffness measured in track and that measured in this apparatus. A pad's dynamic stiffness is consistently at least as great as its tangent stiffness found from the static load/deflection curve. The load/deflection behaviour of a pad in track can be found from measurements in an assembly of rail and sleeper in the laboratory.

Snapping of Low Pinned Arches on an Elastic Foundation

1973 ◽  
Vol 40 (3) ◽  
pp. 741-744 ◽  
Author(s):  
G. J. Simitses
Keyword(s):  
Critical Load ◽  
Elastic Foundation ◽  
Critical Loads ◽  
Entire Range ◽  
Buckling Load ◽  
Stability Studies ◽  
Deflection Curve ◽  
The Stability ◽  
Load Deflection Curve ◽  
Range Of Values

The problem of a low half-sine pinned arch under a quasi-statically applied half-sine load is considered. The low arch is resting on an elastic foundation. Critical loads are obtained by investigating the stability of the equilibrium positions by considering all possible modes of deformation. It is assumed that the behavior of the arch is linearly elastic up to the critical load. The entire range of values for the modulus of the foundation is considered. The results are presented graphically as either critical load (snap-through) or classical buckling load (stable bifurcation) versus the rise parameters for a large number of values of the modulus of foundations. This investigation presents an interesting model for stability studies, because, depending on the value of the rise parameter and the modulus of the foundation, the load-deflection curve exhibits the possibilities of the top-of-the-knee buckling, snap-through buckling through unstable bifurcation, and classical buckling (stable bifurcation).

Free Periodic Motions of an Undamped Two-Degree-of-Freedom Oscillatory System With Nonlinear Unsymmetrical Elasticity

1950 ◽  
Vol 17 (2) ◽  
pp. 185-190
Author(s):  
Walter W. Soroka
Keyword(s):  
Nonlinear Systems ◽  
Linear Systems ◽  
Oscillatory System ◽  
Degree Of Freedom ◽  
The Other ◽  
Periodic Motions ◽  
Deflection Curve ◽  
Approximate Treatment ◽  
Load Deflection Curve ◽  
Two Degree Of Freedom

Abstract Precise solutions are presented for a two-degree-of-freedom oscillatory system containing a preset spring. Such a system is characteristic of an aircraft propeller-engine-supercharger installation. The periodic free motions obtained indicate the possibility of highly unconventional motions when the nonlinearity is pronounced, motions which may be easily overlooked in the usual approximate treatment of nonlinear systems. The results presented in this paper show that one mass may oscillate several times while the other mass is going through one oscillation. The ratio of oscillations of one mass with respect to the other changes with amplitude. By considering the load-deflection curve for the nonlinear spring to be a broken line, periodic motions may be obtained to any desired degree of precision by combining conventional general solutions for two-degree-of-freedom linear systems.

Uniformity of Magnification from Different Electron Microscopes

1967 ◽  
Vol 25 ◽  
pp. 32-33
Author(s):  
Godfrey C. Hoskins ◽  
V. Williams ◽  
V. Allison
Keyword(s):  
Diffraction Grating ◽  
The Other ◽  
Carbon Replica ◽  
Electron Microscopes ◽  
The Stability

The method demonstrated is an adaptation of a proven procedure for accurately determining the magnification of light photomicrographs. Because of the stability of modern electrical lenses, the method is shown to be directly applicable for providing precise reproducibility of magnification in various models of electron microscopes.A readily recognizable area of a carbon replica of a crossed-line diffraction grating is used as a standard. The same area of the standard was photographed in Phillips EM 200, Hitachi HU-11B2, and RCA EMU 3F electron microscopes at taps representative of the range of magnification of each. Negatives from one microscope were selected as guides and printed at convenient magnifications; then negatives from each of the other microscopes were projected to register with these prints. By deferring measurement to the print rather than comparing negatives, correspondence of magnification of the specimen in the three microscopes could be brought to within 2%.

scholarly journals Black Hole Algorithm for Sustainable Design of Counterfort Retaining Walls

2020 ◽  
Vol 12 (7) ◽  
pp. 2767 ◽  
Author(s):  
Víctor Yepes ◽  
José V. Martí ◽  
José García
Keyword(s):  
Black Hole ◽  
Sustainable Design ◽  
Retaining Walls ◽  
The Other ◽  
Trade Off ◽  
Construction Company ◽  
Geometric Variables ◽  
The Stability ◽  
The Cost ◽  
Black Hole Algorithm

The optimization of the cost and CO 2 emissions in earth-retaining walls is of relevance, since these structures are often used in civil engineering. The optimization of costs is essential for the competitiveness of the construction company, and the optimization of emissions is relevant in the environmental impact of construction. To address the optimization, black hole metaheuristics were used, along with a discretization mechanism based on min–max normalization. The stability of the algorithm was evaluated with respect to the solutions obtained; the steel and concrete values obtained in both optimizations were analyzed. Additionally, the geometric variables of the structure were compared. Finally, the results obtained were compared with another algorithm that solved the problem. The results show that there is a trade-off between the use of steel and concrete. The solutions that minimize CO 2 emissions prefer the use of concrete instead of those that optimize the cost. On the other hand, when comparing the geometric variables, it is seen that most remain similar in both optimizations except for the distance between buttresses. When comparing with another algorithm, the results show a good performance in optimization using the black hole algorithm.

scholarly journals Method for Robot Manipulator Joint Wear Reduction by Finding the Optimal Robot Placement in a Robotic Cell

2021 ◽  
Vol 11 (12) ◽  
pp. 5398
Author(s):  
Tomáš Kot ◽  
Zdenko Bobovský ◽  
Aleš Vysocký ◽  
Václav Krys ◽  
Jakub Šafařík ◽  
...  
Keyword(s):  
Angular Velocity ◽  
Dynamic Simulation ◽  
Robot Manipulator ◽  
The Other ◽  
Robotic Arm ◽  
Robotic Cell ◽  
Wear Reduction ◽  
Fixed End ◽  
Robot Placement ◽  
Collaborative Robot

We describe a method for robotic cell optimization by changing the placement of the robot manipulator within the cell in applications with a fixed end-point trajectory. The goal is to reduce the overall robot joint wear and to prevent uneven joint wear when one or several joints are stressed more than the other joints. Joint wear is approximated by calculating the integral of the mechanical work of each joint during the whole trajectory, which depends on the joint angular velocity and torque. The method relies on using a dynamic simulation for the evaluation of the torques and velocities in robot joints for individual robot positions. Verification of the method was performed using CoppeliaSim and a laboratory robotic cell with the collaborative robot UR3. The results confirmed that, with proper robot base placement, the overall wear of the joints of a robotic arm could be reduced from 22% to 53% depending on the trajectory.

scholarly journals Two and three pseudoscalar production in e+e− annihilation and their contributions to (g − 2)μ

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Wen Qin ◽  
Ling-Yun Dai ◽  
Jorge Portolés
Keyword(s):  
Experimental Data ◽  
Theoretical Prediction ◽  
Pseudoscalar Meson ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Vacuum Polarization ◽  
Meson Production ◽  
The Other ◽  
Joint Analysis ◽  
The Standard Model

Abstract A coherent study of e+e− annihilation into two (π+π−, K+K−) and three (π+π−π0, π+π−η) pseudoscalar meson production is carried out within the framework of resonance chiral theory in energy region E ≲ 2 GeV. The work of [L.Y. Dai, J. Portolés, and O. Shekhovtsova, Phys. Rev. D88 (2013) 056001] is revisited with the latest experimental data and a joint analysis of two pseudoscalar meson production. Hence, we evaluate the lowest order hadronic vacuum polarization contributions of those two and three pseudoscalar processes to the anomalous magnetic moment of the muon. We also estimate some higher-order additions led by the same hadronic vacuum polarization. Combined with the other contributions from the standard model, the theoretical prediction differs still by (21.6 ± 7.4) × 10−10 (2.9σ) from the experimental value.

scholarly journals A Fractional SAIDR Model in the Frame of Atangana–Baleanu Derivative

2021 ◽  
Vol 5 (2) ◽  
pp. 32
Author(s):  
Esmehan Uçar ◽  
Sümeyra Uçar ◽  
Fırat Evirgen ◽  
Necati Özdemir
Keyword(s):  
Existence And Uniqueness ◽  
Laplace Transformation ◽  
Cell Phones ◽  
Mobile Network ◽  
The Other ◽  
Banach Fixed Point Theorem ◽  
Propagation Models ◽  
Computer Worms ◽  
Computer Viruses ◽  
The Stability

It is possible to produce mobile phone worms, which are computer viruses with the ability to command the running of cell phones by taking advantage of their flaws, to be transmitted from one device to the other with increasing numbers. In our day, one of the services to gain currency for circulating these malignant worms is SMS. The distinctions of computers from mobile devices render the existing propagation models of computer worms unable to start operating instantaneously in the mobile network, and this is particularly valid for the SMS framework. The susceptible–affected–infectious–suspended–recovered model with a classical derivative (abbreviated as SAIDR) was coined by Xiao et al., (2017) in order to correctly estimate the spread of worms by means of SMS. This study is the first to implement an Atangana–Baleanu (AB) derivative in association with the fractional SAIDR model, depending upon the SAIDR model. The existence and uniqueness of the drinking model solutions together with the stability analysis are shown through the Banach fixed point theorem. The special solution of the model is investigated using the Laplace transformation and then we present a set of numeric graphics by varying the fractional-order θ with the intention of showing the effectiveness of the fractional derivative.

scholarly journals Competing Conventions with Costly Information Acquisition

Games ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 53
Author(s):  
Roberto Rozzi
Keyword(s):  
Information Acquisition ◽  
Evolutionary Model ◽  
Equilibrium Selection ◽  
The Other ◽  
Group Interactions ◽  
Social Coordination ◽  
Long Run ◽  
Stochastic Stability Analysis ◽  
The Stability ◽  
The Cost

We consider an evolutionary model of social coordination in a 2 × 2 game where two groups of players prefer to coordinate on different actions. Players can pay a cost to learn their opponent’s group: if they pay it, they can condition their actions concerning the groups. We assess the stability of outcomes in the long run using stochastic stability analysis. We find that three elements matter for the equilibrium selection: the group size, the strength of preferences, and the information’s cost. If the cost is too high, players never learn the group of their opponents in the long run. If one group is stronger in preferences for its favorite action than the other, or its size is sufficiently large compared to the other group, every player plays that group’s favorite action. If both groups are strong enough in preferences, or if none of the groups’ sizes is large enough, players play their favorite actions and miscoordinate in inter-group interactions. Lower levels of the cost favor coordination. Indeed, when the cost is low, in inside-group interactions, players always coordinate on their favorite action, while in inter-group interactions, they coordinate on the favorite action of the group that is stronger in preferences or large enough.

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