The isotopic constitution of terrestrial rocks and meteorites

The lecture cites numerous data on the isotoplc constitution of sulfur, oxygen, carbon and light gases in iron, stone iron and stone meteorites. A comparison is made between the isotopic consitution of these elements in meteorites and in different rocks of the earth's crust. An analysis of these data leads the author to a number of important conclusions in the realms of geochemistry and cosmochemistry. Considering that the fractionation of isotopes in the earth's crust is the result of differentiation of terrestrial matter, the author concludes that no such differentiation occurred in the meteoritic material (in which no fractioning of isotopes is observed) and that, therefore, all meteorites must have formed by accretion of particles of primordial cosmic dust.Lecture delivered in September of 1957 in Paris at the International Conference on the Use of Radioactive Isotopes in Scientific Research.     

ARGO-YBJ实验硬件系统

中意合作ARGO-YBJ实验采用全覆盖地毯式RPC探测器阵列来探测广延空气簇射事例.讨论了该实验硬件系统结构及工作原理,分析了实验信号采集、处理、传输、缓存和数据输出过程.最后对该实验在"scaler"模式下记录的数据进行了处理分析,结果显示中心区探测器群(Clusters)运行稳定.     

The timing system on the J-TEXT tokamak

This paper describes the timing system designed to control the operation time-sequence and to generate clocks for various sub-systems on J-TEXT tokamak. The J-TEXT timing system is organized as a distributed system which is connected by a tree-structured optical fiber network. It can generate delayed triggers and gate signals (0 μs–4000 s), while providing reference clocks for other sub-systems. Besides, it provides event handling and timestamping functions. It is integrated into the J-TEXT Control, Data Access and Communication (J-TEXT CODAC) system, and it can be monitored and configured by Experimental Physics and Industrial Control System (EPICS). The configuration of this system including tree-structured network is managed in XML files by dedicated management software. This system has already been deployed on J-TEXT tokamak and it is serving J-TEXT in daily experiments.     

The phase diagram for the system zirconium-beryllium

Using the methods of metallographic, thermal, and x-ray qualitative phase analyses and by measuring the hardness, studies have been made of the system zirconium-beryllium, and its phase diagram has been plotted. The presence of four intermediate phases has been shown in the system: ZrBe₂, ZrBe₆, ZrBe₉. and ZrBe₁₃. The first three compounds formed by peritectic reactions at temperatures of 1235, 1475, and 1555 °C, respectively; the last compound melts with an open maximum at 1645 °C. At 965 °C and 5 weight % beryllium a eutectoid forms between the ZrBe₂ and the zirconium. Additions of beryllium to the zirconium lead to a reduction in temperature of the -ß transformation and to the formation of a eutectoid at 800 °C. The solubility of beryllium in -zirconium is less than 0.1 weight % and in ß-zirconium — less than 0.3 weight %. The solubility of zirconium in beryllium does not exceed 0.3 weight %.     

Effect of alpha/beta phase constitution on superplasticity and strength of Zircaloy-4

Strain-rate dependence of the flow stress of Zircaloy-4 in the α, α + β and β modifications has been characterized by stress-relaxation and tensile testing at 732, 760 and 788°C. The proportions of α and β phases were controlled by hydrogen additions. Superplasticity was displayed by α and α + β specimens. It was more prominent in the latter, where the strain rate sensitivity index, $\text{m}$, reached ~0.5 and a characteristic sigmoidal log σ versus log ge curve was observed. A quantitative interpretation of the α + β deformation rate data based on properties and proportions of the individual phases indicates a strong grain boundary sliding component in the superplastic range. Limited data suggest that an $\text{m = 1}$ region emerges at low stresses. An explanation of the entire log σ versus log ge curve is offered through the combination of independent and sequential processes involving diffusion creep, dislocation creep and grain boundary sliding.     

The niobium-carbon system

This paper is a critical review of the available phase equilibria, crystallographic, and thermodynamic data for the niobium-carbon system. The existence of two carbides is well established; both have appreciable ranges of homogeneity. The lower carbide, Nb₂C, exists in two polymorphic forms with the transition being composition dependent and varying from about 2450°C in the carbon-rich region to 2530°C in the niobium-rich region. The upper polymorph decomposes peritectically near 3080°C. The higher carbide, NbC_1−x, melts congruently near 3600°C and undergoes a congruent transformation to an ordered structure at a stoichometry of Nb₆C₅ at 1050°C. Evidence concerning the existence of a third carbide, Nb₄C_3−x, is ambiguous; whether it is stable or metastable remains to be resolved. Below 1500°C the terminal solubility of carbon in niobium is quite small and reaches a maximum of only 5.7 at.% C at 2340°C. The system includes a niobium-rich eutectic at 10.5 at.% C and 2340°C and a carbon-rich eutectic at 60 at.% C and 3300°C.     

BEPCII控制系统前端VME系统研究

介绍了前端VME系统的组成和控制计算机及相关I／O设备控制技术的研究。针对Motorola公司的PowerPC750系列控制计算机MVME5100的实时操作系统VxWorks和板机支持包BSP的调试过程中存在的问题,提出了切实可行的解决方案。在北京正负电子对撞机重大改造工程中,解决了BEPCII前端控制计算机的关键问题,对今后BEPCII控制系统和束测系统前端控制奠定了基础。     

The control system of the CERN-ISOLDE on-line mass-separator facility

With the move of the ISOLDE facility to the PS-Booster from the now closed Synchro-Cyclotron at CERN, a new control system will be implemented for the two separators. Personal computers, based on the Intel 80386 microprocessor running under MS-DOS and Microsoft Windows, are used. Network-wide distributed front end computers, which access the hardware for controls and measurements, are controlled by PC-consoles via a local area network with a PC file server used as a database.     

The waveguide system of the HLS 800 MeV Linac

To upgrade Hefei Light Source(HLS) Linac, eight accelerating units have been constructed to realize fullenergy injection of the storage ring. Each of the units consists of two 3-m accelerators driven by one klystron.The input cavity detuning method was developed to measure and correct the phase length of the RF power distribution waveguide system. The design of the waveguide network and the principles of the detuning method are presented in this paper. After correction, the phase error between the waveguide of the two accelerators was less than ±0.5?, and the maximum electron energy of Linac reached 805 MeV, which is very near the theoretical maximum value of 810 MeV. These results demonstrate that the calibration of the waveguide was successful.     

生物X射线小角散射实验站控制和数据采集系统

生物X射线小角散射光束线站(Biological Small Angle X-Ray Scattering,BioSAXS)是国家蛋白质科学研究上海设施五线六站之一,运动控制和数据采集系统是BioSAXS实验站建设的重要组成部分。介绍了BioSAXS实验站运动控制和数据采集系统,设计实现了基于EPICS(Experimental Physics and Industrial Control System)的运动控制系统,开发了EPICS下的Pilatus探测器的数据采集软件。通过对运动控制、探测器数据采集和光强检测等控制操作界面进行集成,形成了统一的用户界面,并在BioSAXS实验站的调试和运行中得到成功应用。该控制软件界面友好,操作简单,其功能和性能通过了实验验证,满足了BioSAXS线站对运动控制和数据采集系统的需求。     

基于USB传输的多道分析器系统程序设计

介绍一种新型多道分析器系统程序设计，其主要特点是采用通用串行总线USB来实现多道采集接口与PC机的数据传输，具有速度快、通用性好和即插即用的优势。讨论了程序的整体结构、主要功能、能谱显示以及通过USB与硬件接口通讯的方法。程序在Windows下用Visual Basic6.0编写。     

The design of the J-type neutron flux distribution measurement system

This paper introduces the design of a J-type aeroball system that the tube penetrates the lateral wall of reactor pressurized vessel (RPV), then immediately goes down to the vessel bottom and then goes up through the lower core support plate into the reactor core. Some experimental results related to gas flowing within a thin tube are presented in the paper, such as the gas friction drag coefficient on the ball’s way and etc. From theoretical and experimental viewpoints, the feasibility of the system is proved in pneumatic holding-up and β measurement aspects. In order to ensure an enough ratio of signal to noise, the maximum distance between two measuring points in water reactors is given. The paper gives out the measuring number per two-assemblies width N_i=Int(n_i/2+0.51), which is the accuracy relation between the number of fuel assembly and the minimum one of measuring point to only reconstruct 2D neutron flux distribution completely by the measured data.