基于NiosⅡ和SD卡的数据采集系统的设计

在NiosⅡ软核处理器上采用SD卡设计了一种嵌入式文件系统,并在该文件系统和FPGA的基础上设计了一种便携式数据采集系统.     

Fast-digitizing and track-finding electronics for the vertexdetector in the Opal experiment at the Large Electron Positron Collider(LEP) at CERN

The vertex detector front-end electronics are described. It comprises fast analog-to-digital conversion circuits and a fast programmable track trigger processor. The function of the electronics is to examine, within one large electron-positron beam crossing (22 μs), data generated in the detector for the evidence of charged particle tracks. Measurements of ionization drift times are based on a gated 93-MHz oscillator synchronized to a precision crystal clock and give points in space. The axial positions of these points along the detector are found by analyzing the difference in time of arrivals of signals at the ends of the detector (z by timing). Particle tracks are found by 36 track finders operating in parallel and are matched by semicustom coincidence chips. The track information is used in the first stage of data reduction in the Opal experiments (the first-level trigger)     

不同测量条件下μ子源项特征模拟

采用CRY宇宙射线模拟软件包,获取不同测量条件下μ子的特征信息,研究不同条件下宇宙射线中μ子的通量、能谱、角分布等特征规律。研究结果表明:太阳活动极大时会使μ子通量降低;地磁场的影响使得赤道附近的μ子通量比极地地区要小且能谱蓝移;海拔升高则会显著增大μ子通量,但总体能量均值降低。模拟结果与相关实验结果具有很好的一致性。     

USB2.0通讯在数据采集系统中的应用

设计USB数据采集系统的难点在于:其一,对USB传输、事务、信息包以及握手信号等相关概念的正确理解和应用;其二,正确处理好数据采集与数据传输之间的时序关系。针对一种实际的数据采集系统的设计特点,对设计过程进行了较详细的阐述。     

便携式多道能谱分析系统的研制

介绍了一种基于数字寻峰技术的多道能谱测量系统.利用可编程逻辑器件设计灵活方便的特点,借助VHDL硬件描述语言,设计了数字寻峰电路,利用单片机进行采集和管理数据,并通过USB口上传数据到主计算机.与传统的多道能谱测量系统相比,本系统具有结构简单,功耗小,操作方便,体积小等特点.     

Model for Thickness Dependence of Radiation Charging in MOS Structures

The model considers charge buildup in MOS structures due to hole trapping in the oxide and the creation of sheet charge at the silicon interface. The contribution of hole trapping causes the flatband voltage to increase with thickness in a manner in which square and cube dependences are limiting cases. Experimental measurements on samples covering a 200 - 1000 ? range of oxide thickness are consistent with the model, using independently obtained values of hole-trapping parameters. An important finding of our experimental results is that a negative interface charge contribution due to surface states created during irradiation compensates most of the positive charge in the oxide at flatband. The tendency of the surface states to "track" the positive charge buildup in the oxide, for all thicknesses, applies both in creation during irradiation and in annihilation during annealing. An explanation is proposed based on the common defect origin of hole traps and potential surface states.     

Finite element analysis of ion-implanted diamond surface swelling

We present experimental results and numerical finite element analysis to describe surface swelling due to the creation of buried graphite-like inclusions in diamond substrates subjected to MeV ion implantation. Numerical predictions are compared to experimental data for MeV proton and helium implantations, performed with scanning ion microbeams. Swelling values are measured with white-light interferometric profilometry in both cases. Simulations are based on a model which accounts for the through-the-thickness variation of mechanical parameters in the material, as a function of ion type, fluence and energy. Surface deformation profiles and internal stress distributions are analyzed and numerical results are seen to adequately fit experimental data. Results allow us to draw conclusions on structural damage mechanisms in diamond for different MeV ion implantations.     

Overview of the SLD

The SLD is a second generation detector for the SLAC Linear Collider (SLC). It is optimized for Z° physics and exploration of new physics in the Z° energy region. The SLD will have a CCD vertex detector, high resolution drift chambers for momentum measurement, a ?erenkov Ring Imaging Detector for particle identification, and calorimetry based on lead/liquid argon followed by an iron/gas system. The detector covers the full solid angle.     

高速数字式TDC

本文介绍的高速TDC用来快速决定粒子流发生对撞的初步位置。粒子对撞时将产生大量新出射粒子。通过测定这些新粒子出射束到达零级触发器的时间,即可确定对撞的顶点位置,进而为Ⅰ级触发器提供计算粒子横向能量所需知的方向角加权因子sinθ。该TDC由全数字式GaAs集成电路组成,其时间分辨达到226 ps。     

基于全工况数学模型诊断核电汽轮机热力系统故障的新思路

利用核电汽轮机热力系统大范围变工况(全工况)数学模型建立核电热力系统故障诊断系统。通过数学模型对对象系统机理的描述,避免了以往神经网络等推理方法中对大量运行数据的需要,更具实用性。由于引入了反映设备运行性能的特性参数概念。通过特性参数随其主导因素的变化关系诊断系统设备故障,避免了依据表面现象判断故障的困难,并使故障诊断结果具有量化标准。能对现场运行和维修提出有益的指导。