Phase matched scanning optical parametric chirped pulse amplification based on pump beam deflection

Combined with the optical beam deflection,a novel approach of phase matched broadband scanning optical parametric chirped pulse amplification(OPCPA)was proposed.For this scheme,there was no superfluous operations to the chirped signal pulse which propagated in a changeless direction straightforward,but the pump beam were deflected in space with time by passing through a KTN crystal,which was applied with varied driving voltage.The theories of phase matching of each chirped signal frequency based on pump beam deflection was analyzed detailedly.And the type-I amplification of chirped signal with 800 nm central wavelength and 20 nm bandwidth pumped by 532 nm in BBO crystal was simulated as a case in point.The simulation results showed that the spectral distribution of chirped signal pulse was almost the same as the initial form,i.e.,there was nearly no narrowing on the amplified spectrum by using of the scanning OPCPA based on pump beam deflection.In addition,the simulations demonstrated that it was worth minimizing the voltage deviation applied to KTN crystal as much as possible for the sake of better waveform,larger bandwidth and higher conversion efficiency of amplified signal pulse in the proposed scanning OPCPA.

Analytic Static Deflection Solutions of Uniform Cantilever Beams Resting on Nonlinear Elastic Rotational Boundary

In the paper,the analytic static deflection solutions of uniform cantilever beams resting on nonlinear elastic rotational boundary are developed by the Modified Adomian Decomposition Method(MADM).If the applied force function is an analytic function,then the deflection function can be derived and expressed in Maclaurin series.A recurrence relation for the coefficients of the Maclaurin series is derived.It is shown that the proposed solution method is accurate and efficient.The solution method can be successfully applied to the uniform cantilever beam and non-linear elastic rotational boundary problem.

Deflection analysis of reinforced concrete beams strengthened with carbon fibre reinforced polymer under long-term load action

This paper presents the results of an experimental research on reinforced concrete beams strengthened with an external carbon fibre reinforced polymer(CFRP) layer under long-term load action that lasted for 330 d.We describe the characteristics of deflection development of the beams strengthened with different additional anchorages of the external carbon fibre composite layer during the period of interest.The conducted experiments showed that the additional anchorage influences the slip of the external layer with respect to the strengthened element.Thus,concrete and carbon fibre composite interface stiffness decreases with a long-term load action.Therefore,the proposed method of analysis based on the built-up-bars theory can be used to estimate concrete and carbon fibre composite interface stiffness in the case of long-term load.

Critical transitions in the shape morphing of kirigami metallic glass

Kirigami, the ancient Japanese paper cutting technique, has been applied to achieve high stretchability and low energy loss of designed metallic glass. Despite the exploration of the underlying deformation mechanism of kirigami-inspired structures from the energy point of view, the morphable responses of the kirigami patterns and the origin of the kirigami response are yet to be fully understood. This study reveals the mechanical driven-forms of the kirigami structure with the corresponding deformation stages. Based on the beam deflection theory, the elastic buckling behavior of kirigami metallic glass is manifested and a critical force prediction model is developed. Moreover, a force concentration parameter is introduced in the rigid-plastic deformation stage, predicting the nominal ultimate force. The kirigami-inspired facture force is firstly proposed. The findings of these models are in good agreement with the experimental sizedependent kirigami responses, and expected to provide significant insights into the understanding of the deformation behavior and the design of kirigami metallic glasses.

Using portable falling weight deflectometer to determine treatment depth of subgrades in highway reconstruction of Southern China

Based on a highway reconstruction project in southern China,this study aims to put forward a method to determine the proper treatment depth of the existing subgrade.First,some field tests including the Beckman beam deflection test and portable falling weight deflectometer(PFWD)test were carried out.The results showed that there was a good correlation between the Beckman beam deflection(L)and PFWD modulus(Ep).Subsequently,a subgrade section was excavated and backfilled with cement-stabilized soil in layers.Compaction test,dynamic cone penetrometer rate test,plate load test and Beckman beam deflection test were performed to evaluate the treatment effect.To make sure,the subgrade was treated deeply enough,the Beckman beam deflection(L)was used as the controlled indicator among all the measured indexes for it was the hardest metric to meet.According to the design deflection and decreasing law of the measured deflections with the different number of the stabilized layers,the treatment depth was finally determined.As the PFWD test is superior to the deflection test in the detection efficiency,and the deflection value can be calculated from PFWD modulus by correlation formulas,thus the latter index can be used as a more suitable parameter for estimating the treatment depth instead of the former.Consequently,based on the measured PFWD moduli of the existing subgrade,six treatment schemes considering different treatment depths were proposed.It was confirmed that the method developed from this study is feasible and worth being extensively applied.