Optical storage of circular airy beam in atomic vapor

The realization of quantum storage of spatial light field is of great significance to the construction of high-dimensional quantum repeater.In this paper,we experimentally realize the storage and retrieval of circular Airy beams(CABs)by using theΛ-type three-level energy system based on the electromagnetically induced transparency in a hot rubidium atomic vapor cell.The weak probe beam field is modulated with phase distribution of CABs by a spatial light modulator.We store the probe circular Airy beam(CAB)into the rubidium atomic vapor cell and retrieve it after the demanded delay.We quantitatively analyze the storage results and give corresponding theoretical explanations.Moreover,we investigate the autofocusing and self-healing effect of the retrieved CAB,which indicates that the properties and beam shape of CAB maintain well after storage.Our work will have potential applications in the storage of high-dimensional quantum information,and is also useful for improving the channel capacities of quantum internet.

On the Innovation,Design,Construction,and Experiments of OMEGA-Based SSPS Prototype:The Sun-Chasing Project

This study systematically introduces the development of the world’s first full-link and full-system ground demonstration and verification system for the OMEGA space solar power satellite(SSPS).First,the OMEGA 2.0 innovation design was proposed.Second,field-coupling theoretical models of sunlight concentration,photoelectric conversion,and transmitting antennas were established,and a systematic optimization design method was proposed.Third,a beam waveform optimization methodology considering both a high beam collection efficiency and a circular stepped beam shape was proposed.Fourth,a control strategy was developed to control the condenser pointing toward the sun while maintaining the transmitting antenna toward the rectenna.Fifth,a high-efficiency heat radiator design method based on bionics and topology optimization was proposed.Sixth,a method for improving the rectenna array’s reception,rectification,and direct current(DC)power synthesis efficiencies is presented.Seventh,high-precision measurement technology for high-accuracy beam-pointing control was developed.Eighth,a smart mechanical structure was designed and developed.Finally,the developed SSPS ground demonstration and verification system has the capacity for sun tracking,a high concentration ratio,photoelectric conversion,microwave conversion and emission,microwave reception,and rectification,and thus satisfactory results were obtained.

Investigation of the Free Vibrations of Radial Functionally Graded Circular Cylindrical Beams Based on Differential Quadrature Method

In the current research,an effective differential quadrature method(DQM)has been developed to solve natural frequency and vibration modal functions of circular section beams along radial functional gradient.Based on the high-order theory of transverse vibration of circular cross-section beams,lateral displacement equation was reconstructed neglecting circumferential shear stress.Two equations coupled with deflection and rotation angles were derived based on elastic mechanics theory and further simplified into a constant coefficient differential equation with natural frequency as eigenvalue.Then,differential quadrature method was applied to transform the eigenvalue problem of the derived differential equation into a set of algebraic equation eigenvalue problems.Natural frequencies of the free vibrations of cylindrical beams with circular cross-sections were calculated at one time,and corresponding modal functions were solved together.The obtained numerical results indicated that the natural frequencies of functionally graded(FG)circular cylindrical beams obtained using differential quadrature method agreed with the results reported in related literatures.In addition,influences of varying gradient parameters on the modal shapes of circular cylindrical beams were found to be strongly consistent with previous studies.Numerical results further validated the feasibility and accuracy of the developed differential quadrature method in solving the transverse vibration of FG circular cross-section beams.

Experimental research on mechanical properties of prestressed truss concrete composite beam encased with circular steel tube

Tests of 4 simply supported unbonded prestressed truss concrete composite beams encased with circular steel tube were carried out. It is found that the ratio of the stress increment of the unbonded tendon to that of the tensile steel tube is 0.252 during the using stage,and the average crack space of beams depends on the ratio of the sum of the bottom chord steel tube's outside diameter and the secondary bottom chord steel tube's section area to the effective tensile concrete area. The coefficient of uneven crack distribution is 1.68 and the formula for the calculation of crack width is established. Test results indicate that the ultimate stress increment of unbonded tendon in the beams decreases in linearity with the increase of the composite reinforcement index β0. The pure bending region of beams accords with the plane section assumption from loading to failure. The calculation formula of ultimate stress increment of the unbonded tendon and the method to calculate the bearing capacity of normal section of beams have been presented. Besides,the method to calculate the stiffness of this sort of beams is brought forward as well.

THE DYNAMIC PLASTIC RESPONSE CHARACTERISTICS OF CIRCULAR BEAM

In this paper the problem of a circular beam subjected to radial impact by a rigid mass at its lip in its own plane is investigaleil on the basis of rigid-perfectly plastic assumption. The analytical solution of the particle velocities is obtained as the junction of travelling plastic hinge location. Ky analysing the solution, some special properties oj circular beam problem are found.

Effects of circular beam oscillation technique on formability and solidification behaviour of selective laser melted Inconel 718:From single tracks to cuboid samples

The inherent drawbacks of selective laser melting technique including serious micro-pore and element microsegregation problems destroy the mechanical property of the component.To overcome this problem,a new approach,circular beam oscillation,was successfully applied in the SLMed Inconel 718 samples including single tracks,thin walls and cuboid samples.On one hand,circular beam oscillation reduces the micro-pores in molten pools and cuboid samples,increasing the relative density of the cuboid sample to 99.95%.On the other hand,circular beam oscillation suppresses the element microsegregation,reducing the formation of Laves phases in SLMed Inconel 718 samples.Moreover,circular beam oscillation enhances the<001>texture of thin walls and the<101>texture of cuboid samples.The improvement of formability and microstructure of the SLMed samples with oscillation is closely related to cooling rate,thermal gradient and stirring effect during the solidification process.Therefore,circular beam oscillation shows the possibility to overcome the key bottlenecks of the traditional SLM technology and to realize a further industrial application of SLM technology.

A new absolute nodal coordinate formulation beam element with multilayer circular cross section

A systematic numerical integration method is applied to the absolute nodal coordinate formulation(ANCF)fully parameterized beam element with smooth varying and continuous cross section.Moreover,the formulation for the integration points and weight coefficients are given in the method which is used to model the multilayer beam with a circular cross section.To negate the effect of the bending stiffness for the element used to model the high-voltage electrical wire,the general continuum mechanical approach is adjusted.Additionally,the insulation cover for some particular types of the wire is described by the nearly incompressible Mooney-Rivlin material model.Finally,a static problem is presented to prove the accuracy and convergence properties of the element,and a dynamic problem of a flexible pendulum is simulated whereby the balance of the energy can be ensured.An experiment is carried out in which a wire is released as a pendulum and falls on a steel rod.The configurations of the wire are captured by a high-speed camera and compared with the simulation results.The feasibility of the wire model can therefore be demonstrated.

Circular Airy beams realized via the photopatterning of liquid crystals[Invited]

The generation of an autofocusing circular Airy beam(CAB)is realized via a liquid crystal(LC)geometric phase plate with a simple configuration.The fabrication of the LC plate is based on the photoalignment technology and dynamic exposure skill.A focal length of 74 cm is obtained,and the propagation dynamics are consistent with the simulations.Besides,a defocusing CAB is also generated,and the switch between the autofocusing and defocusing CABs can be achieved by controlling the input polarization state.This work provides a convenient and flexible approach to acquire CABs,which will promote the CAB-related applications and researches.

BACKSCATTERING ON A FINITE-LENGTH RIGID CIRCULAR CYLINDER DUE TO A NARROW SOUND BEAM

The geometrical theory of diffraction (GTD) ,combined with Fourier transformation, has been applied to the back - scattering on a finite - length rigid circular cylinder due to a narrow sound beam. The theoretical results are confirmed by the model experiment.