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??In survival analysis, most existing approaches for analysing right-censored failure time data assume that the censoring time is independent of the failure time. However, investigators often face problems involving dependent censoring, i.e., failure time and censoring time are possibly dependent and they may be censored one another, especially in clinical trials. Without accounting for such dependence, survival distributions cannot be estimated consistently. Numerous attempts to model this dependence have been made. Among them, copula models are of particular interest because of their simple structure. Proportional hazard model analysis for informative right-censored data has been discussed in this paper. An Archimedean copula is assumed for the joint distribution function of failure time and censoring time variables. Under the conditions of identifiability of the parameter of the Archimedean copula, the maximum likelihood estimators of the parameter of Archimedean copula, the parameters and the cumulative hazard function of PH model are worked out. Extensive simulation studies show that the feasibility of the proposed method and the consistency of the estimators.     

低温泵用椰基活性炭材料的选择和比较

为了选择用于核聚变研究领域中在氢、氦气环境下的低温吸附泵所用的吸附剂,在初步筛选基础上,比对了4种椰基活性炭材料。采用扫描电镜对材料微观结构进行了扫描,用比表面积及孔径分析仪测定了等温吸附性能,最终获得了活性炭样本的比表面积、微孔比表面积份额、不同孔径所对应的孔容等性能数据;通过对实验结果的比对分析,为筛选适用于核聚变研究环境下低温吸附泵使用的吸附剂材料,提供了重要的实验数据。     

HL-2Mװ���ܱߴų��ֲ���NBI���ߴ����η���

The time and space distribution of the toroidal and poloidal magnetic field surrounding the HL-2M tokamak was simulated with the electromagnetic field simulation software CST Studio from Germany. The results show that the magnetic field intensity surrounding the neutralizer tank and ion source of NBI device was more than2?10^-3T, so the magnetic shielding of NBI neutralizer tank and ion source was necessary. Then the magnetic field distribution surrounding NBI neutralizer tank and ion source after shielding with iron was simulated with CST Studio.     

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Characteristics of ion emission from the ferroelectric media was investigated under low pressure condition. By utilizing high-speed camera photography, spectral analysis, and particle-in-cell simulation coupling with Monte Carlo collision, the optical emission composition and images from ferroelectric surface, plasma evolution of ferroelectric surface discharge, the mechanism of ion generation and the forming of ion current are discussed. These results are useful for further understanding to ferroelectric ion sources.     

����PLC �����IJ��������HL-2A װ�ÿ���λ�ƿ���ϵͳ�������ʵ��

In order to realize automatic control of HL-2A limiter displacement?? an automatic control system of limiter displacement has been designed. The two-phase hybrid stepper motor was adopted. The S7- 300PLC was used as the main controller and the FM453 was used as the positioning module of the stepping motor. The drive, control and detection of the stepping motor have been realized. At the same time, the communication with the host computer was completed, and the functions such as the limiter displacement settings and data display of the HL-2A tokamak have been achieved.     

HL-2A װ�õ��Ӳ�ϵͳ�߹����ٵ��ܵ���

A test platform for the TH2103A klystrons and the high power microwave components is developed. The RF driver, four port circulator, RF load and high power cathode power supply are installed on the test bed. A short pulse test is carried out on the test bed. The parameters of the 4 klystrons are optimized by scanning the currents in the 3 focusing coils and the high power microwave transmission components are conditioned. The output power of the 4 klystrons reached 449kW, 417kW, 460kW and 450kW when the pulse duration was 30ms, respectively. The test result is an important reference for the LHCD system on HL-2A tokamak.     

HL-2M װ��CO2 ɫɢ�����ǵĽ����׶���侵�����о�

For the influence of the mental retroreflector processing and installation error on the optical propagation, the relationship between the dihedral angle error of the retroreflector and the reflected beam was studied. The impacts of the surface and morphology of retroreflector on reflection properties was analyzed, and the reflectivity of different retroreflector cone was measured and compared. The polarization characteristics of retroreflector was also analyzed. According to the study results, for the retroreflector in CO₂ dispersion interferometer on HL-2M tokamak, the surface machining accuracy should be within 0.3μm, the dihedral angle error should be a positive tolerance and controlled within 30', the surface coating is firm and uneasy to fall off.     

实验物理与工业控制系统平台在HL-2A主机测控系统中的应用

描述了利用实验物理与工业控制系统(EPICS)平台对HL-2A主机运行参数进行的集中测控系统开发。系统采用s7nodave设备驱动模块,实现了SoftIOC与各PLC的通讯,将各子系统的PLC集成到了EPICS控制系统中。通过对关系型数据库和应用层软件CSS中数据归档及报警等组件的扩展与配置,实现OPI层与各个子系统的实时通信。测控系统成功地将HL-2A主机参数集中在EPICS平台下运行,为下一代装置的主机集中测控系统设计打下了基础。     

Tracy-Widom�ֲ�����Ӧ��

??Tracy and Widom found a new type of probability distribution in the study of high dimensional random matrices in the 1990s, which is nowadays normally called Tracy-Widom distribution. It is used to described the limiting distribution of the extremal eigenvalues in Gaussian Unitary Ensemble. Later on, the study in the past two decades indicates that Tracy-Widom distribution is universal like normal distribution and can be well used to describe a lot of seemingly distinct random phenomena. As illustrations, the paper briefly review nine widely studied random models, each of which is more or less related to Tracy-Widom distribution. Compared to normal distribution, Tracy-Widom distribution has horribly intricate distribution function, density function and moments. people need to use deep mathematical knowledge and advanced computation technology in order to extend and to apply Tracy-Widom distribution in practice. But it is absolutely worthy further study on account of its importance.     

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