Identifying the degree of mode localization in Cross-tied cable networks by using energy-based approach

2021 ◽  
pp. 107754632110132
Author(s):  
Javaid Ahmad

The use of cross-tie is one of the effective countermeasures to suppress the undesired cable vibration in the cable-stayed bridges. The major benefits offered by the cross-tie solution are the increase in the in-plane stiffness and the flow of energy toward the higher order nodes. However, the formation of closely spaced local modes is one of the major disadvantages of the Cross-tied cable networks. There are only few studies available to understand the formation of local modes. In the current study, an energy-based approach is developed to differentiate between the global and the local modes. In the proposed approach, the kinetic energy equations are formulated to compute the energy stored in arbitrary cable segments. In the current study, the advantages of the proposed energy-based approach over the existing amplitude-based approach have been discussed. The suggested approach has been applied to multiple cable networks, and a comparison has been drawn between the amplitude-based approach and the proposed energy-based approach.

2021 ◽  
pp. 68-71
Author(s):  
S.N. Afanasiev

The reaction 16O(γ, p)3H3 induced by bremsstrahlung photons of endpoint energy Emaxγ = 150 MeV has been studied by the method of a diffusion chamber in a magnetic field. The energy dependence of the total cross section has been measured in the energy range from the threshold and has been founded a broad resonance centered at 55 MeV. The rate of decrease in the cross section undergoes a change in the region around 55 MeV. A comparison was made with the cross section for reactions 4He(γ, p)3H and 12С(γ, р)3H2. The agreement between the shapes of distributions for the (γ, p)3H reactions is evident and was concluded that the mechanism of interaction of the γ-quantum with the nucleus is similar. The dependence of average kinetic energy of particles on the total kinetic energy was determined. In the whole energy interval, the distribution for a proton is more than the statistical distribution. Distribution of relative energy of the proton and 3H nucleus in their c.m.s. does not agree with the predictions of the mechanism of photon absorption by an α-particle cluster, but at energies above the maximum, it agrees with calculations within the framework of the quasi-deuteron model of photoabsorption.


1985 ◽  
Vol 85 ◽  
pp. 137-140
Author(s):  
P.L. Lamy

AbstractThe relevance of the bulk density as a physical parameter characterizing interplanetary dust grains is discussed. The various measurements which lead to a determination of this parameter are reviewed. The specific case of the collected interplanetary dust grains is considered.The bulk density of interplanetary dust grains has been and is still a matter of controversy. This quantity cannot, in general, be directly measured; it is used to relate the mass and the size of a grain. This duality stems from physics itself as there are interactions sensitive to the mass (e.g., gravitational forces) while others are sensitive to the size or the cross-section (e.g., light scattering, radiation pressure, gas and plasma interactions). The measuring technics of the grains reflect this duality as, for instance, impact sensors are generally sensitive to the kinetic energy and thus to the mass, while optical sensors are sensitive to the cross-section. One sees that the density is not strictly speaking the relevant parameter, but what is needed is a relationship between mass and average cross-section.


1968 ◽  
Vol 23 (7) ◽  
pp. 970-978
Author(s):  
H. Schlumbohm

Measurements of the photoemission caused by collisions of ground level He+- and Ne+-ions with Ar- and Kr-atoms have shown several multipletts of Ar II and Kr II within the investigated wavelength range of 3500 to 5500 A. At a high rate the charge transfer processes occur into excited states of Ar* and Kr*. The reactions are endothermic with a deficit of internal energy between 6 and 19 eV.The cross sections measured for several chosen transitions start at characteristic threshold energies between 10 and 25 eV. Above the threshold the cross sections rise slowly with increasing energy when Ne* is the colliding ion and very fast for He+. Above 50 to 100 eV the cross sections show nearly constant values. — The minimum kinetic energy values are calculated, which can just fill up the deficits of internal energy, and are shown to be equal to the measured threshold energies. Thus it follows that the pseudo-crossing of the potential energy curves of the quasimolecules occurs at an energy value equal to the asymptotic level of the above curve.


1995 ◽  
Vol 22 (5) ◽  
pp. 1001-1020 ◽  
Author(s):  
Raju Tuladhar ◽  
Walter H. Dilger ◽  
Mamdouh M. Elbadry

In cable-stayed bridges, modelling the cables is of particular significance for the seismic behaviour of the structure. The common practice of modelling a cable by a single truss element is inadequate for seismic response calculations because it essentially precludes the lateral cable vibration modes. The present paper studies the influence of cable vibrations on the seismic response of cable-stayed bridges. Three bridge examples with different spans and properties were used. Cable vibrations are accounted for through the use of multiple links for each cable. Cable vibration effects are found to be significant for seismic response calculations, particularly when the cable fundamental frequencies are overlapping with the first few frequencies of the bridge. Parametric studies are conducted with regard to the number of links per cable, the effect of the modulus of elasticity of the cables, and different earthquakes on the bridge response. Modelling the cables by two links per cable such that at least the fundamental modes of the cable vibrations are represented can significantly account for the effect of cable vibrations. It is also observed that the equivalent modulus method cannot in any way account for the cable vibration effects. Key words: cable vibration, dynamic analysis, equivalent modulus, multiple links, seismic response, cable-stayed bridge.


Author(s):  
Len Gelman

The new second and higher order spectral technique, the cross-covariance of complex spectral components, is proposed for monitoring damage of structure and machinery Normalization of the proposed technique is also developed. It is shown by simulation that the proposed technique provides effectiveness gain for detecting of damage compared to the higher order spectra.


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