Study of Ternary Fission Produced in 12C Bombarding 209Bi Target with Medium Energy

Alternative layers of target material,which were prepared by evaporating ²⁰⁹Bi on the surface of mica foils,were irradiated with ¹²C ions.Ternary fission events in which three fragments of comparable mass were produced in 2525－47.5MeV/A ¹²C+²⁰⁹Bi reaction,were recorded by the mica detectors with 2π geometry.The observed probability ratio of ternary fission relative to binary fission in 2π geometry was modified to 4π geometry spatial in terms of the Monte Carlo method.The values of ratioes increase with the bombarding energy,and are compared with the calculation result of the cascade fission model.     

Experimental study on the 1.94-μm laser performance of c-Cut Tm:YAP crystal with various doping concentration

The influence of the thulium ion concentration on the 1.94-??m laser performance of c-cut Tm:YAP crystal was investigated in this paper. Three crystals with 3, 4, and 5% Tm³⁺ (atom concentration) were examined at 18°C. Our experimental results showed that, the best power performance was obtained with the 4% Tm:YAP crystal. By using 24.8 W of incident pump power at 795 nm, a maximum of 7.5 W of output power was obtained. The slope efficiency was 48.8%, corresponding to diode-to-Tm conversion efficiency of 30.2%.     

微波场中Josephson结的微波发射与吸收研究

采用数值仿真方法,研究微波场中约瑟夫森结微波感应台阶处的功率特性。发现微波场中约瑟夫森结不止吸收辐射,也发射辐射的情况。得到微波辐照和结电阻对功率吸收和发射的影响规律。结果表明,处于发射功率的状态对应的偏置电流范围占整个台阶总电流范围的比例可以趋于50%。这一发现对约瑟夫森结理论和应用研究具有重要的意义。     

HPLC测定注射用复方头孢西丁钠

建立注射用复方头孢西丁钠中两种有效成分的定量分析方法.采用Kromasil C18色谱柱(250mm×4.6mm,5μm),以乙腈-磷酸二氢钾(0.03mol·L-1)-10％四丁基氢氧化铵(35∶63.5∶1.5,V/V/V),用85％的磷酸调pH=4为流动相,流速1.0mL·min-1,进样量10μL,柱温30℃,在230nm的波长下进行他唑巴坦、头孢西丁两种物质的定量分析.他唑巴坦、头孢西丁浓度分别在0.125-0.50mg·mL-1(r=0.9998)、0.5-2.0mg·mL-1(r=0.9999)范围内与峰面积呈良好线性关系;方法的回收率(n=9)分别为99.7％、100.2％;样品相对标准偏差分别为1.5％、0.2％;稳定性实验表明上述两种成分在室温条件下8h内稳定.本法首次建立了注射用复方头孢西丁钠的含量测定方法,该法快速、简便、准确,重复性好,适用于该药物的含量测定.     

纳米尺度流动速度计算的新方法

采用流体力学中流量与流速的计算和分子动力学相结合的方法,模拟液态氩在纳米通道内的三维Poiseuille流动和驱动方腔流动,计算流体流速.结果表明:平板形纳米通道内,该方法求得的流速与传统分子动力学方法所求流速基本吻合,可以用该方法计算不同壁面情况下的流速;对于纳米方腔通道内的流体,在不同模型下两种方法计算出的流速分布大致相同,但是其边界速度差别很大,在边界的速度计算方面新方法的精确度更高,收敛速度比传统方法快.     

Simultaneous strain and temperature measurement with a single fiber Bragg grating based on the polarization properties analysis

In this paper, a new technique for discrimination of temperature and strain exploiting the polarization properties of a single normal fiber Bragg grating (FBG) is firstly proposed and experimentally demonstrated. The spectral characterization of the differential group delay (DGD) of the FBG is studied. The evolution of the DGD response of the FBG as a function of temperature and strain is analyzed. The numerical simulations and experimental results suggest that implementing two independent measurements of the resonance wavelength shift and the changes of the DGD can discriminate the temperature and strain effects.     

Improving histogram-based image contrast enhancement using gray-level information histogram with application to X-ray images

Many applications of histogram-based techniques for the purposes of image enhancement are well known. However, these techniques often fail to produce satisfactory results for a broad variety of low-contrast images (e.g., X-ray images). In this paper, we propose a new form of histogram for image contrast enhancement. The input image is first divided into several equal-sized regions according to the intensities of gradients, their corresponding statistical values of gray levels are then modified respectively, and finally the processed histogram for the whole image is obtained by the summation of all the weighted values of regions. The fundamental characteristic of this new form of histogram is that the amplitudes of its components can objectively reflect the contribution of the gray levels to the representation of image information. Accordingly, this new histogram is called gray-level information histogram. The performance of many histogram-based enhancement techniques might be improved dramatically using the proposed histogram. Testing on the X-ray images validates the effectiveness of the new histogram.     

Primary result of ~(236)U measurement with accelerator mass spectrometry at CIAE

The rare isotope 236U has a half-life of 2.342(3)×107 years,and is produced principally by thermal neutron capture on 235U.The isotopic atom ratio of 236U/238U depends on the integral thermal neutron flux received by the material of interest.236U is potentially useful as a fingerprint for indicating the presence of neutron-irradiated uranium usually originating from nuclear activity.By extracting negative molecular ion UO- from the uranium oxide target,simulating the 236U16O- beam transport with 238U16O- an...     

First experimental research of the bunch compressor at CAEP

Magnetic bunch compressor is one of the key technologies on the path to next generation accelerator driven facilities. In this paper we report the design principles and the first experimental research of the bunch compressor developed at Chinese Academy of Engineering Physics （CAEP）. The length of the bunch after compressor is found to be about 0.7 ps （rms） and the peak current exceeds 500 A when operated in the optimized condition. The sensitivity of the bunch length on the phase of the acceleration field and magnetic field of the bunch compressor was also measured and analyzed.     

广义H non映射的滑模变结构控制同步

基于可线性化的非线性离散变结构跟踪控制方法实现了广义H non映射混沌系统的同步 .广义H non映射的混沌吸引子比H non映射的混沌吸引子要复杂得多 ,对于保密通信来说 ,这种复杂性正是所期望的 .提出的同步方法允许参数有适当的失配程度 ,这对工程实现是非常有利的 ,理论分析和仿真结果证实了该方法的有效性