A New Method to Investigate InGaAsP Single-Photon Avalanche Diodes Using a Digital Sampling Oscilloscope

A near-infrared single-photon detection system is established by using pigtailed InGaAs/InP avalanche photodiodes. With a 50GHz digital sampling oscilloscope, the function and process of gated-mode (Geiger-mode) single-photon detection are intuitionally demonstrated for the first time. The performance of the detector as a gated-mode single-photon counter at wavelengths of 1310 and 1550nm is investigated. At the operation temperature of 203K,a quantum efficiency of 52% with a dark count probability per gate of 2. 4 * 10~(-3), and a gate pulse repetition rate of 50kHz are obtained at 1550nm. The corresponding parameters are 43% , 8. 5 * 10~(-3), and 200kHz at 238K.

Improved digital processing method used for image motion measurement based on hybrid opto-digital joint transform correlator

Hybrid opto-digital joint transform correlator (HODJTC) is effective for image motion measurement, but it is different from the traditional joint transform correlator because it only has one optical transform and the joint power spectrum is directly input into a digital processing unit to compute the image shift. The local cross-correlation image can be directly obtained by adopting a local Fourier transform operator. After the pixel-level location of cross-correlation peak is initially obtained, the up-sampling technique is introduced to relocate the peak in even higher accuracy. With signal-to-noise ratio >= 20 dB, up-sampling factor k >= 10 and the maximum image shift <= 60 pixels, the root-mean-square error of motion measurement accuracy can be controlled below 0.05 pixels.

Crossing the phantom divide in brane cosmology with curvature corrections and brane-bulk energy transfer

We consider the Randall-Sundrum brane-world model with bulk-brane energy transfer where the Einstein-Hilbert action is modified by curvature correction terms: a four-dimensional scalar curvature from induced gravity on the brane, and a five-dimensional Gauss-Bonnet curvature term. It is remarkable that these curvature terms will not change the dynamics of the brane universe at low energy. Parameterizing the energy transfer and taking the dark radiation term into account, we find that the phantom divide of the equation of state of effective dark energy could be crossed, without the need of any new dark energy components. Fitting the two most reliable and robust SNIa datasets, the 182 Gold dataset and the Supernova Legacy Survey (SNLS), our model indeed has a small tendency of phantom divide crossing for the Gold dataset, but not for the SNLS dataset. Furthermore, combining the recent detection of the SDSS baryon acoustic oscillations peak (BAO) with lower matter density parameter prior, we find that the SNLS dataset also mildly favors phantom divide crossing.

重离子加速器注入器电源控制器的设计；Design of digital power control system applied in sector focusing cyclotron

设计了一种应用于兰州重离子加速器注入器的电源控制器,该控制器基于微处理器AT-mega128,结合MAX7000系列的复杂可编程器件和RTL8019AS网关芯片来实现对电源系统的控制,并通过RS-232总线实现与上位机的串口通信。应用结果表明,该控制器具有良好的通用性、灵活性、可远程控制及性能稳定等特点,实现了注入器磁铁电源10-4量级的幅度稳定性,使注入器引出的束流强度、束流品质、束流稳定性和供束效率等得到很大的提高。

基于CPLD和ATMEGAL128的数字电源系统的设计；Design of Digital Power Control System Based on CPLD and ATMEGAL128

介绍了一种基于CPLD设计的电源控制模块,并且利用Atmegal128单片机和RTL8019S实现逻辑功能和远程控制功能。该电源系统主要用于重离子加速器注入器(SFC)中,具有很好的灵活性、可远程控制、性能稳定等特点。

Digital regionalization of geomorphology in Xinjiang

National Natural Science Foundation of China [40871177]; Project of State Key Lab of Resources and Environmental Information System [088RA304SA]; CAS Knowledge Innovation Project

Digital simulation in a thin layer spectroelectrochemical cell with minigrid platinum electrode by microregion approximation explicit finite difference method

The microregion approximation explicit finite difference method is used to simulate cyclic voltammetry of an electrochemical reversible system in a three-dimensional thin layer cell with minigrid platinum electrode. The simulated CV curve and potential scan-absorbance curve were in very good accordance with the experimental results, which differed from those at a plate electrode. The influences of sweep rate, thickness of the thin layer, and mesh size on the peak current and peak separation were also studied by numerical analysis, which give some instruction for choosing experimental conditions or designing a thin layer cell. The critical ratio (1.33) of the diffusion path inside the mesh hole and across the thin layer was also obtained. If the ratio is greater than 1.33 by means of reducing the thickness of a thin layer, the electrochemical property will be far away from the thin layer property.

Application of digital image analysis to the study of banded spherulite during growing and melting process

A digital image analysis(DIA) technique can be applied directly to the image obtained by polarizing microscope. The time-resolved DIA apparatus including image collecting, showing and data analysis has been home-made. As an example, it has been used to study the banded spherulite in the blends of poly(epsilon-caprolactone) (PCL) and poly(styrene-ran-acrylonitrile) (SAN).

Differences in the rDNA-bearing chromosome divide the Asian-Pacific and Atlantic species of Crassostrea (Bivalvia, Mollusca)

Karyotype and chromosomal location of the major ribosomal RNA genes (rDNA) were studied using fluorescence in situ hybridization (FISH) in five species of Crassostrea: three Asian-Pacific species (C. gigas, C. plicatula, and C. ariakensis) and two Atlantic species (C. virginica and C. rhizophorae). FISH probes were made by PCR amplification of the intergenic transcribed spacer between the 18S and 5.8S rRNA genes, and labeled with digoxigenin-11-dUTP. All five species had a haploid number of 10 chromosomes. The Atlantic species had 1-2 submetacentric chromosomes, while the three Pacific species had none. FISH with metaphase chromosomes detected a single telomeric locus for rDNA in all five species without any variation. In all three Pacific species, rDNA was located on the long arm of Chromosome 10 (10q)-the smallest chromosome. In the two Atlantic species, rDNA was located on the short arm of Chromosome 2 (2p)-the second longest chromosome. A review of other studies reveals the same distribution of NOR sites (putative rDNA loci) in three other species: on 10q in C. sikamea and C. angulata from the Pacific Ocean and on 2p in C. gasar from the western Atlantic. All data support the conclusion that differences in size and shape of the rDNA-bearing chromosome represent a major divide between Asian-Pacific and Atlantic species of Crassostrea. This finding suggests that chromosomal divergence can occur under seemingly conserved karyotypes and may play a role in reproductive isolation and speciation.