An automated, 0.5 Hz nano-foil target positioning system for intense laser plasma experiments

We report on a target system supporting automated positioning of nano-targets with a precision resolution of 4 μm in three dimensions. It relies on a confocal distance sensor and a microscope. The system has been commissioned to position nanometer targets with 1 Hz repetition rate. Integrating our prototype into the table-top ATLAS 300 TW-laser system at the Laboratory for Extreme Photonics in Garching, we demonstrate the operation of a 0.5 Hz laser-driven proton source with a shot-to-shot variation of the maximum energy about 27% for a level of confidence of 0.95. The reason of laser shooting experiments operated at 0.5 Hz rather than 1 Hz is because the synchronization between the nano-foil target positioning system and the laser trigger needs to improve.

Remote positioning system based on GPS/GPRS

Considering the need of target positioning,a remote positioning system is designed based on global positioning system(GPS)and general packet radio service(GPRS);The data collection terminal is based on microcontroller unit(MCU)PIC24FV301.It uses GPRS network to create wireless link and transmits GPS source information which is collected by LEA-5H board to monitor center on the Internet.The monitor center obtains the target information through processing and analysis of the calculated data.Actual operation results indicate that the designed system has excellent performance and achieves the goal of the remote location.

美国国家点火装置中低温定位器产生的背景中子通量密度的计算

W.C.Mead等人[1]对美国国家点火装置(NIF)内的氘氚燃料反应产生的信号中子与低温定位器(CTP)、靶室壁反应产生的背景中子和背景光子的通量密度进行了计算。论文对同一系统进行再次研究,得到与W.C.Mead不同的结论。论文对W.C.Mead等人的研究进行勘误和拓展,使用MCNP对NIF中CTP和靶室壁对背景中子和背景光子的产生情况进行了计算和分析。通过计算在靶室内不同半径不同角度上的背景中子通量密度,确定了在靶室内最佳信噪比的角度,同时对探测器布置在靶室内的位置提出了建议。并且在W.C.Mead等人的研究基础上,改变CTP在靶室中的位置,计算并对比了CTP在靶室内不同位置上,所产生的背景中子和背景光子通量密度。

A real-time detection and positioning method for small and weak targets using a 1D morphology-based approach in 2D images

A small and weak target detection method is proposed in this work that outperforms all other methods in terms of real-time capability.It is the first time that two-dimensional(2D)images are processed using only one-dimensional1D structuring elements in a morphology-based approach,enabling the real-time hardware implementation of the whole image processing method.A parallel image readout and processing structure is introduced to achieve an ultra-low latency time on the order of nanoseconds,and a hyper-frame resolution in the time domain can be achieved by combining the row-by-row structure and the electrical rolling shutter technique.Experimental results suggest that the expected target can be successfully detected under various interferences with an accuracy of 0.1 pixels(1σ)under the worst sky night test condition and that a centroiding precision of better than 0.03 pixels(1σ)can be reached for static tests.The real-time detection method with high robustness and accuracy is attractive for application to all types of real-time small target detection systems,such as medical imaging,infrared surveillance,and target measurement and tracking,where an ultra-high processing speed is required.

Ionized gas clouds near the Sagittarius Arm tangent

Radio recombination lines（RRLs） are the best tracers of ionized gas. Simultaneous observations of multi-transitions of RRLs can significantly improve survey sensitivity. We conducted pilot RRL observations near the Sagittarius Arm tangent by using the 65-m Shanghai Tian Ma Radio Telescope（TMRT） equipped with broadband feeds and a digital backend. Six hydrogen RRLs（H96α-H101α）at C band（6289 MHz-7319 MHz） were observed simultaneously toward a sky area of 2°× 1.2° by using on-the-fly mapping mode. These transitions were then stacked together for detection of ionized gas. Star forming complexes G48.6＋0.1 and G49.5-0.3 were detected in the integrated intensity map.We found agreements between our measured centroid velocities and previous results for the 21 known HII regions in the mapped area. For more than 80 cataloged HII region candidates without previous RRL measurements, we obtained new RRL spectra at 30 targeted positions. In addition, we detected 25 new discrete RRL sources with spectral S/N 〉 5σ, and they were not listed in the catalogs of previously known HII regions. The distances for 44 out of these 55 new RRL sources were estimated.

A Novel Imaging Algorithm for Airborne Bistatic Squint SAR with Unparallel Trajectories

A novel analytical imaging algorithm is proposed for the strip-map mode of airborne bistatic squint SAR with unparallel trajectories. The algorithm derives the two-dimensional （2D） spectrum formula of the point target echo by using the contribution ratios of Doppler frequency modulation ratios of the transmitter and receiver as the weighting coefficients. Through decoupling the target position against the tracks of the transmitter and receiver, the range parameter and the azimuth one in the spectrum formula are separated. In 2D frequency domain, 2D Chirp-Z transform （2D-CZT） is applied to correcting the migrations of the echo along the range and azimuth after the bistatic deformation term has been compensated, so the target image is precisely focused. The advantage of the algorithm is easy to be expanded to the virtual wide swath by blocking the radar data along the range and azimuth to limit the 2D residual migrations. Simulation results confirm the validity of the 2D-CZT algorithm.

腕表式弱激光血管外照射治疗仪的研制

在对目前市场上的各种激光血管外照射治疗仪的优缺点进行分析研究的基础上,研制了一种腕表式弱激光治疗仪。该治疗仪采用了双靶点照射、靶血管定位器及激光定位仓等多种创新设计及技术,在保证安全的前提下实现了治疗效果的明显提升。