Impact is one of very important subjects which always have been considered in mechanical science. Nature of impact is such that which makes its control a hard task. Therefore it is required to present the transfer of impact to other vulnerable part of a structure, when it is necessary, one of the best method of absorbing energy of impact, is by using Thin-walled tubes these tubes collapses unde...

composites materials are widely used because of their high specific stiffness and strength. although the methods and techniques of designing these materials are well developed, however, the research on the behavior of these materials under impact and dynamic loadings are still under progress. in this article the crushing and energy absorption of composite tubes under axial dynamic loadings are ...

We study how coincident Dirichlet 3-branes absorb incident gravitons polarized along their world volume. We show that the absorption cross-section is determined by the central term in the correlator of two stress-energy tensors. The existence of a non-renormalization theorem for this central charge in four-dimensional N = 4 supersymmetric Yang-Mills theories shows that the leading term at low e...

Conventional material removal of BK7 optical glass will normally result in brittle fracture at the surface, generating severe subsurface damage and poor surface finish. Subsurface damages induced by grinding strongly influence the mechanical strength and optical quality of optical glasses. However, through ductile mode grinding it is possible to reduce the surface and subsurface cracks. It is m...

Herein, three-photon absorption (3PA) effect of a symmetrical fluorene-based molecule, pumped with 38 ps Q-switched 1064 nm laser pulses, is reported. An accurate Gaussian fitting method is used to obtain the three-photon absorption cross-section. The obtained three-photon absorption cross-section, 8.54 x 10(-76) cm(6) s(2), is very high. The irradiance limiting nonlinear transmittance is as lo...

The absorption spectrum represents an important aspect of single semiconductor nanocrystals (NCs), revealing the morphology and orientation of the NCs. By conducting quantitative photoluminescence excitation spectroscopy based on a single-photon counting method, we succeed in clarifying the absorption cross-section spectrum of neutral excitons in single CdSe/ZnS NCs. With the values of the abso...

Magneto-optical traps have been used for several decades. Among fundamental mechanisms occurring in such traps, the magnitude of the multiple scattering is still unclear. Indeed, many experimental situations cannot be modeled easily, different models predict different values of the reabsorption cross section, and no simple experimental measurements of this cross section are available. We propos...

A simple recipe for revealing classical-like contributions in optical potential cross sections is proposed. The recipe is based on the fact that the classical-like properties are not expected to depend on the actual value of ¯ h. This allows us to identify the classical-like characteristics of an optical potential cross section by simply repeating the calculation with different values of ¯ h, a...

Motivated by black hole experiments as a consequence of the TeV-scale gravity arising from modern brane-world scenarios, we study the absorption problem for the massive scalars when the spacetime background is a (4 + n)dimensional Reissner-Nordström black hole. For analytic computation we adopt the near-extreme condition in the spacetime background. It is shown that the low-energy absorption cr...