Status of CSNS H- ion source

A new H^- ion source has been installed successfully and will be used to serve the China Spallation Neutron Source (CSNS). In this paper, we report various components of the ion source, including the discharge chamber, temperature, cooling system, extraction electrodes, analyzing magnet, remote control system and so on. Compared to the previous experimental ion source, some improvements have been made to make the ion source more compact and convenient. In the present arrangement, the Penning field is generated by a pair of pole tip extensions on the 90° analyzing magnet instead of by a separate circuit. For the remote control system, F3RP61-2L is applied to the accelerator online control system for the first time. In the running of the ion source, a stable pulse H^- beam with a current of 50 mA at an energy of 50 keV is produced. The extraction frequency and pulse width is 25 Hz and 500 μs, respectively. Furthermore, an emittance scanner has been installed and measurements are in progress.     

混凝土构件长期干缩应力的计算

本文用有限元法从砼的水分扩散方程中求出湿度和自由干缩应变场,分别由砼的线性和非线性蠕变理论及拉应变软化模型,推导出计算砼构件的干缩应力的递推公式,并编制了电算程序。计算表明,非线性理论的结果与线性理论的结果相差不大,而拉应变软化模型的结果与前两者有较大差异。     

D4型量子包络代数的Gelfand-Kirillov维数

本文研究了D₄ 型量子包络代数的Gelfand-Kirillov 维数的计算问题. 利用文献[1] 中给出的Gelfand-Kirillov 维数的计算方法和文献[2] 中给出的D₄ 型量子包络代数的Groebner-Shirshov 基计算了D₄型量子包络代数的Gelfand-Kirillov 维数, 得到的主要结果是D₄ 型量子包络代数的Gelfand-Kirillov 维数为28. 希望此结果为计算D_n型量子包络代数的Gelfand-Kirillov 维数提供一些思路.     

电子器件散热风扇气动噪声管道声学模态截止控制技术

深度学习输入特征的选择直接影响其分类性能,为了进一步提高基于深度学习的鸟类物种识别模型的分类性能,该文提出一种多特征融合识别方法。该方法首先通过短时傅里叶变换、梅尔倒谱变换和线性调频小波变换分别计算得到鸣声信号的3种语图样本集,然后分别利用3种语图样本集训练3个基于VGG16迁移的单一特征模型,将3个模型的输出进行自适应加权求和实现融合,并修正了加权交叉熵函数以克服样本不平衡的问题,最后对语图进行分类实现鸟类物种的识别。以ICML4B鸣声库的35种鸟类为研究对象,对比了4种模型的平均识别准确率(MAP),结果表明特征融合模型较单一特征模型的MAP最大提高了0.307;选择输入语图的持续时间分别为100 ms、300 ms以及500 ms,对比不同持续时间下4种模型的测试MAP值,结果表明持续时间为300 ms时4种模型的MAP值均为最高;对比了不同信噪比下4种模型的识别效果,多特征融合模型的识别准确率随着信噪比的下降降低最少。说明在选择合适的语图持续时间后,该文提出的特征融合模型能得到更高的识别准确率,具有一定的抗噪能力,且训练参数少,更适合于少样本鸟类的识别。     

对苯醌二亚胺与对苯乙炔共聚物的金属配合物催化法合成与表征

在金属配合物的存在下,通过N,N′-二氯对苯醌二亚胺与1,4-二炔基-2,5-二（烷氧基）苯共聚,得到了一系列新型交替共聚物聚[N,N′-对苯醌二亚胺-1,4-二炔基-2,5-二（烷氧基）苯]（PAn-PPE）。采用FT-IR、1H-NMR、GPC、XRD、UV-Vis、PL、TGA等测试手段对共聚物的化学结构和性能进...     

模糊神经网络的一种快速学习算法

本文对文献[1]《一种改进的模糊参数神经网络学习算法》中提出的F-BP算法进行分析研究，提出了一种效率更好的快速F—BP学习算法．在此算法中对模糊数的计算方法进行改进，减少了模糊神经网络训练及推理中的运算量，从而提高学习效率．     

Characteristics of Double Gamma-Ray Bursts

Double gamma-ray bursts （DGRBs） have two well-separated sub-bursts in the main prompt emission and the typical time interval between them is in the hundreds of seconds. Among DGRBs, gamma-ray bursts （DGRBs） 110801A and 120716A are the ones with known redshifts. However, unlike GRB 110801A, we show that the two sub-bursts of GRB 120716A is severally similar to the short- and long-duration GRBs, thus it is difficult to explain the origin of GRB 120716A by the popular models on the central engine of GRBs. We suggest that some mechanisms of x-ray flares in GRBs, i.e., a post-merger millisecond pulsars or the jet precession in a black hole hyperaccretion system may produce the DGRB.     

973 RFQ 水冷调谐系统(英文)

由于束流的传输效率对射频四极场加速器(RFQ) 中射频场的分布极其敏感,所以在RFQ 的运行过程中不再采用传统的调谐器调谐RFQ。水冷调谐的方法基本上不影响RFQ 射频场的分布,所以适用于RFQ 的调谐。中国科学院高能物理研究所为C-ADS、CSNS 预研RFQ 项目开发建造了一套水冷调谐系统,使用RF 相位差作为控制量进行RFQ 水冷调谐,相位差的控制精度达到了1°运行结果显示该系统满足了RFQ 的调谐需求。介绍了该系统的水冷系统、调谐控制系统和一些运行经验。Since the beam transmission of a Radio Frequency Quadrupole(RFQ) Accelerator is very sensitive to the field profile, the ordinary frequency tuning method by the local movable tuner is no more adopted in an RFQ operation. The tuning method by controlling cooling water temperature is widely adopted to tune the RFQ due to the less affect on the RFQ field profile. A Resonance Control Cooling System (RCCS) is developed and commissioned for the 973 RFQ,which is a R&D project for C-ADS and CSNS RFQ at IHEP. This system adopts the RF phase difference as control variable to tune the RFQ. The control accuracy of the RF phase difference is about 1°. The running of the 973 RFQ shows that the RCCS works very well and fully satisfies the operation requirement of the RFQ. In this paper, the water skid, resonance control system of the RCCS and the operation experiences will be presented.     

面向信息处理的维吾尔语词语分类体系及标记研究(Ⅱ)

研制《维吾尔语词语分类体系及其标记集》是维吾尔文信息处理的支柱工程．动词在维吾尔语句子构成中常常是一个句子的核心．本文在以往有关维吾尔语诃胜标注研究成果的基础上，提出了一个面向信息处理的现代维吾尔语动词体系及其标记集，并且对维吾尔语动词的形态特征、语法范畴以及短语组合功能等方面进行了详细的描述．     

Thermal analysis of the CSNS H~- ion source

There are two cooling systems to maintain the thermal stability of the CSNS H- ion source during its operation:Air-cooling in the source body of the discharging chamber and water-cooling in the flange on which the discharging chamber is installed.The optimal cooling parameters to ensure the operation of the H- ion source are determined through a thermal analysis.In addition,a transient analysis is also performed to know exactly the transient temperature variation during the whole 40 ms period of the pulsed ...