Very low output-impedance RF system for a proton synchrotron withlow drive power requirements

In order to solve a power consumption problem of the driver stage in the cathode-follower RF system, a grid-cathode driving scheme is investigated by means of an isolation transformer. A very low output impedance can be realized together with a voltage gain a few tens of times higher than that of a cathode-follower. The model system has been tested under frequency modulation in the 1-3-MHz range at 40-Hz repetition; the output impedance is less than 30 Ω and the driver voltage 62 V to produce a 1.2-kV peak at the cavity gap     

油水界面仪的研制及其应用

以7．4×108Bq(137)Cs为辐射源,研制了一台用于检测贮油罐中的油水分界面的油水界面仪,从而实现自动切水,消除了由于人工切水所产生的跑油和由此而引起的着火爆炸事故的发生。     

Observation of atomic steps on single crystal surfaces by a commercial scanning electron microscope.

Atomic steps on (111) and (100) crystal surfaces of Pt were observed using a commercial scanning electron microscope (SEM) in secondary electron mode. By comparing the SEM images and those by reflection electron microscopy (REM), the observed contrast was confirmed to be that from atomic steps on crystal surfaces. The contrast mechanism is briefly discussed. One application of this imaging technique is also shown.     

Cr-Fe-C合金镀层的电化学磨蚀行为研究

利用新开发的从Cr^3 水溶液中电镀非晶态铬合金的新工艺,在铜合金基体上获得了厚度30μm以上的Cr-Fe-C合金镀层。对经不同温度下热处理的镀层进行了显微硬度和XRD分析和腐蚀磨损电化学行为研究。结果表明：该镀层热处理后伴随逐渐向晶态转化可出现明显的硬化现象。钝性的Cr-Fe-C合金镀层在电解质中局部表面受到摩擦作用时,镀层的磨蚀是腐蚀和磨损两种失效形式相互加强和共同作用的结果。与传统的铬及铬合金镀层相比,该镀层可作为经济的耐磨和耐磨蚀镀层使用。     

Low energy electron storage ring with tunable compaction factor

A low energy electron storage ring is designed to have many desirable properties, such as varying momentum compaction factor, damping partition numbers, favorable betatron tunes for multiturn accumulations, and excellent dynamic aperture. This storage ring can be used for debunching rf linac beams in one turn, for compression of linac pulses, and more importantly for a compact photon source based on inverse Compton scattering of laser beams.     

JSP中对数据库的访问技术研究

目前,数据库在Web服务中得到广泛的应用.本文介绍了JSP访问数据库的常用驱动程序,详细分析了JSP访问数据库的步骤和方法,并给出了用JDBC-ODBC桥和纯Java驱动程序实现了在JSP中访问数据库Access和Mysql的具体实例.     

U-Boot的启动分析及基于S3C44B0的移植

U-Boot作为一种通用的BootLoader,可以方便地移植到其他硬件平台上。简单介绍了BootLoader和U-Boot,通过对U-Boot的启动过程以及源代码目录分析,最后完成了基于S3C44B0的移植。     

基于贝叶斯估计的起重机械主梁的可靠性预测

针对起重机械主梁工作环境的复杂性和在相同工作环境下可靠性数据不足的问题,将贝叶斯估计方法和数据拟合相结合,以主梁的退化量作为性能参数,建立了起重机械主梁在工作环境下的可靠性预测模型;利用贝叶斯估计方法最大限度地将工作现场数据和历史试验数据相结合,及时更新主梁在工作环境下性能参数的分布函数,进而估计工作环境下不同时刻主梁的可靠度,最后采用最小二乘法估计主梁的可靠性函数.预测结果表明,起重机械主梁失效满足参数为(9.290,225.9)的2参数威布尔分布,得到为了满足主梁98％的可靠度要求,最小的维修间隔周期为149天.     

Unfolding core asymmetries with x-ray emission images in symmetry diagnostic experiments

A novel inversion technique is proposed to unfold core asymmetries at the source with x-ray emission images, which were obtained from imploded surrogate capsules in symmetry diagnostic experiments. The axisymmetrical core emission can be expanded as a Fourier series, with Legendre polynomials and spherical Bessel functions as bases concerned with polar angle and radius, respectively. A least-squares estimator is employed to obtain the unknown coefficients from its two-dimensional image data. The unfolded Legendre coefficients can be further used to test modeling of drive asymmetries in hohlraums. This technique is also demonstrated with a proof-of-principle experiment performed on the Shenguang II laser facility [L. Zunqi et al., Chin. J. Lasers B10, 6 (2001)].