Security of quantum key distribution using two-mode squeezed states against optimal beam splitter attack

For the beam splitter attack strategy against quantum key distribution using two-mode squeezed states, the analytical expression of the optimal beam splitter parameter is provided in this paper by applying the Shannon information theory. The theoretical secret information rate after error correction and privacy amplification is given in terms of the squeezed parameter and channel parameters. The results show that the two-mode squeezed state quantum key distribution is secure against an optimal beam splitter attack.

HYDROSTATIC PRESSURE CALCULATION AND OPTIMIZATION FOR DESIGN OF BEAM & SLIDE-REST GUIDEWAYS IN HEAVY DUTY CNC VERTICAL TURNING MILL

Aiming at the approximate error of commonly used methods on calculation of hydrostatic pressures of closed hydrostatic guideways with multiple pockets, a more accurate solution is proposed. Taking design of beam ＆ slide-rest guideways for a heavy duty CNC vertical turning mill as an example, under an assumption that stiffnesses of guideways and their jointing structure are sufficiently large, the pressures of the pockets can be attained by adding a co-planarity equation that constrains pocket centers. Then, an optimization model is built to minimize the highest pocket pressure under additional constraints that are posed on the highest seal margin pressure, the highest levitating pressure of the pockets, and the maximum deformation of the guideways. The optimization problem is solved sequentially by using the methods of design of experiments and adaptive simulated annealing on iSIGHT software platform. The results show significant improvements to the original design. Optimized maximum hydrostatic pressure meets the requirement of hydraulic system.

Recent developments in the structural design and optimization of ITER neutral beam manifold

This paper describes a new design of the neutral beam manifold based on a more optimized support system.A proposed alternative scheme has presented to replace the former complex manifold supports and internal pipe supports in the final design phase.Both the structural reliability and feasibility were confirmed with detailed analyses.Comparative analyses between two typical types of manifold support scheme were performed.All relevant results of mechanical analyses for typical operation scenarios and fault conditions are presented.Future optimization activities are described,which will give useful information for a refined setting of components in the next phase.

Beam dynamics study of the photoinjector at Wuhan advanced light source

Background A full-energy LINAC is under development at Wuhan Advanced Light Source(WALS)to provide beams for the 1.5 GeV storage ring proposed as a fourth-generation synchrotron radiation light source and a future free electron laser(FEL)facility.The LINAC starts from a photoinjector that is able to produce electron beams with low emittance(<1 mm·mrad),small relative energy spread(<0.5%),and high bunch charge(~1 nC).Purpose and methods To minimize the output emittance and RMS bunch length for the purpose of improving the photoinjector brightness,the influence of different laser pulse profiles on the slice emittance is investigated,and the beam dynamics simulation is performed with non-dominated sorting genetic algorithm-II(NSGA-II)combining with ASTRA code to find the optimal solution at a bunch charge of 1 nC.Results and conclusion In this paper,the beam dynamics optimization of the photoinjector is presented in detail;the simulation results imply that the laser pulse profile with 1σtruncated Gaussian distribution in transverse and flat-top-like temporal distribution is beneficial to the improvement of beam brightness of the photoinjector,which shows an output emittance of 0.63 mm·mrad in the case of intrinsic thermal emittance of 0.43 mm·mrad.

Highly robust ground moving target detection and relocation method for distributed satellites

The performance of ground moving target detection for distributed satellites will be affected signifi-cantly when there is an image registration error,clutter decorrelation and array error.In this paper,a new approach to moving target detection and relocation is proposed based on multi-channel and multi-pixel adap-tive signal processing in an image domain.First,multi-channel and multi-pixel joint data are equated to a simple array model.Given that there is an image registration error,the real steering vector of the moving target can be estimated through a space projection approach.The optimal beam forming approach is used to cancel clutter,and at the same time the cross-track velocity of the mov-ing target can be determined by searching for the peak value of the cost function.The moving target can then be relocated on the SAR image.The simulation results indicate that this method has a good robustness to image registration error,clutter decorrelation and array error.The detection performance and the estimation accuracy are significantly improved.

Optimization of the lattice function in the planar undulator applied for terahertz FEL oscillators

Since the beta function of the electron beam within the undulator has a great influence on the power gain of the free electron laser（FEL）,optimization of the undulator lattice becomes important.In this paper,the transfer matrix of the planar undulator is obtained from differential equations of the electron motion.Based on this,the lattice function of the planar undulator in a terahertz FEL oscillator proposed by Huazhong University of Science and Technology（HUST-FEL） is optimized and the expressions of the average beta function are derived.The accuracy of the optimization result was confirmed well by the numerical method.The application range of this analytical method is given as well.At last,the emittance growth in the horizontal direction due to the attenuation of the magnetic field is discussed.