Anti-detection technology of cat eye target based on decentered field lens

Optoelectronic imaging equipment is easy to expose to active laser detection devices because of ＂cat eye＂ effect. In this paper, we propose a new structure of optical system to reduce the retroreflector effect of a cat eye target. Decentered field lens structure is adopted in the design without sacrificing imaging quality and clear aperture. An imaging system with±30° field of view is taken for example. The detailed design and simulation results are presented. The results indicate that this kind of optical system can reduce the retroreflection signal substantially and maintain acceptable imaging performance.

Thermal Compensation and Fuzzy Control for Developing a High-Precision Optical Lens Mold

Precision plastic lenses often exhibit dimensional deviations due to the thermal expansion of the mold during injection molding.Although this deviation is smaller in micron-sized(1–5μm)lenses,it exceeds the tolerance requirement of such lenses.It is difficult to resolve this dimensional issue by using injection molding parameters(e.g.,melt temperature,injection speed,and hold pressure).In this study,the thermal analysis of a mold was conducted,and it was confirmed that the deviation of lens dimension was caused by the thermal instability and thermal expansion of the mold.Due to the inconsistent heat distribution of the fixed and the movable side of the mold,the position of the location system was displaced approximately 1 to 5μm.In this study,thermal compensation technology for this the mold was investigated.The temperature on both sides of the mold was measured,and mold temperature could be adjusted automatically using a control strategy based on fuzzy theory.During the mold preheating or mass production stage,the temperature on both sides of the mold could be easily adjusted to quickly obtain the required temperature range.The dilatation on both sides of the mold was revised to improve the alignment accuracy of the cavity,and the decenter error of these injection lenses was reduced to 1μm.This technology can markedly improve the production yield and efficiency of plastic products requiring an extremely high dimensional accuracy.

Single-shot grating-based x-ray differential phase contrast imaging with a modified analyzer grating

X-ray grating interferometer has attracted widely attention in the past years due to its capability in achieving x-ray phase contrast imaging with low brilliance source. However, the widely used phase stepping information extraction method reduces system stability and prolongs data acquisition time by several times compared with conventional x-ray absorption- based imaging. The mechanical stepping can be avoided by using a staggered grating, but at the cost of low vertical spatial resolution. In this paper, employing a modified staggered grating and the angular signal radiography, we proposed a single-shot grating-based x-ray differential phase contrast imaging with decent vertical spatial resolution. The theoretical framework was deduced and proved by numerical experiments. Absorption, phase, and scattering computed tomography can be performed without phase stepping. Therefore, we believe this fast and highly stable imaging method with decent resolution would be widely applied in x-ray grating-based phase contrast imaging.

Decent Work and Industrial Upgrading in Global Production Network: a Case of China Apparel Industry

China apparel industry, which is deeply embedded in the global production network (GPN), faces two urgent issues, social upgrading and economic upgrading. The study of GPN places great emphasis on the two issues. Based on the survey of Ningbo apparel industry, four key components of decent work in China apparel industry are discussed. The role of buyers in promoting decent work in suppliers can't be neglected. There are significant correlations between business type and some indicators of decent work. Though the majority of the apparel firms are engaging in processing, more and more firms are involved in marketing and branding. The upgrading trajectory of China apparel industry leads to the economic and social performances.

On Answering the Question Related to the Legal Regulation of Working Hours in the New Era:Western Experience and Chinese Approach

The popularity of flexible working hours around the world has slowed down the historical trend of reducing working hours.It even shows signs of regression.Whether and how to guide the cur-rent society with flexible working hours to return to the historical track of reducing working hours,improve the quality of working hours,and promote a smooth transition from the era of traditional standard work-ing hours to the era of flexible working hours has become a question related to the legal regulation of working hours in the new era.In this regard,although Western countries have proposed new regulatory concepts and carried out legislative practices with distinctive charac-teristics,the limitations of legal regulation capabilities have prevented them from proposing a package of institutional solutions.The advan-tage of China in the ability of legal regulation of working hours has been gradually formed in the legislation on working hours unnder the leadership of the CPC in the past century.It enables China to break through the limitations of the West and propose a Chinese approach to answer the question of the legal regulation of working hours in the new era from three aspects:limiting the extension of working hours,improving the quality of flexible working hours,and optimizing the funnctions of the multi-funnctional regulatory system for working hours.

Effect of Critical Beam Radius on Self-focusing of cosh-Gaussian Laser Beams in Collisionless Magnetized Plasma

Effect of critical beam radius on self-focusing of cosh-Gaussian laser beams in collisionless magnetized plasma under ponderomotive nonlinearity forms the main core of present work. To investigate propagation dynamics of cosh-Gaussian laser beams in collisionless magnetized plasma, well established parabolic equation approach under WKB and paraxial approximations is employed. Our study is crucially pivoted on the concept of critical curve and subsequent determination of numerical interval for decentered parameter to sustain the competition between diffraction and self-focusing during the propagation of laser beam. Additionally, in the present study an interesting feature in the self-focusing region of the critical curve has been attempted for different values of decentered parameter.

Relativistic Self-Focusing of Hermite-cosh-Gaussian Laser Beam in Magnetoplasma with Exponential Plasma Density Ramp

In the present manuscript,we analyse the effect of exponential plasma density ramp for relativistic selffocusing of Hermite-cosh-Gaussian laser pulse in magnetoplasma.The exponential plasma density ramp is found to be more prominent in achieving the stronger self-focusing of Hermite-cosh-Gaussian laser beam in comparison to the tangential plasma density ramp.We propose a theoretical model for propagation of Hermite-cosh-Gaussian laser pulse in magnetoplasma with exponential density ramp.The nonlinearity in the medium arises because of the relativistic motion of electrons,being responsible for relativistic self-focusing.Equation of the beam width parameter is set up by taking the expression for the dielectric function and following Wentzel-Kramers-Brillouin(WKB)with paraxial ray approximations for mode indices m=0,1 and 2.Effect of decentered parameter is also analysed,which results in stronger self-focusing of the Hermite-cosh-Gaussian laser beam.Stronger self-focusing of laser beam is more pronounced in high density plasma with higher magnetic field.

Electron Acceleration by a radially polarised cosh-Gaussian laser beam in vacuum

In this paper,a radially polarised cosh-Gaussian laser beam(CGLB)is used to study the electron acceleration produced in vacuum.A highly energetic electron beam can be achieved by a CGLB,even with comparatively low-powered lasers.The properties of a CGLB cause it to focus earlier,over a shorter duration than a Gaussian laser beam,which makes it suitable for obtaining high energies over small durations.It is found that the energy gained by the electrons strongly depends upon the decentering parameter of the laser profile.It is also observed that for a fixed value of energy gain,if the decentering parameter is increased,then the intensity of the laser field decreases.The dependence of the energy gained by electrons on the laser intensity and the laserspot size is also studied.

A new TDOA algorithm based on Taylor series expansion in cellular networks

Time difference of arrival(TDOA)is the positioning technique with the most potential in cellular mobile telecommunication systems.The Taylor series expansion method has been widely used in solving nonlinear equations for its high accuracy and good robustness.However,the performance of the Taylor’s method depends highly on the initial estimation.Therefore,one new algorithm,hybrid optimizing algo-rithm(HOA)was proposed,which combines the Taylor series expansion method with the steepest decent method.The steepest decent method features fast convergence at the initial iteration and small computation complexity.HOA takes great advantage of both methods.Simulation results show that HOA achieves better performance on positioning accuracy and efficiency.

A Place to Call Home——Rescued moon bears get to live a decent life

On February 8, 2006, a piece of sad news came out of the Moon Bear Rescue Center in Chengdu, capital city of southwest China's Sichuan Province. Andrew, the first moon bear rescued by the Animals Asia Foundation, which sponsors the center, died of liver cancer, thought to have arisen from the massive infec-