Object location fire precision test technology by using intersecting photoelectric detection target

To improve four across screens system measurement precision on flying projectile location, the new method that adds two incline screens to four intersecting screens system to form six intersecting screens was put forward and the flying object coordinate test model was set up. This method not only gains object coordinate but also measures object's pitching and azimuth angle that can amend coordinates and improve measurement precision. The differential methods were used to analyze their measure errors, which came from the angle of intersection screen, the thick of screen, the time and distance of measuring, and give out measure errors distributing. The experimental result shows the new measure method can improve measurement precision that meets test demand.     

Prototype of time digitizing system for BESⅢ endcap TOF upgrade

The prototype of a time digitizing system for the BESⅢ endcap TOF (ETOF) upgrade is introduced in this paper. The ETOF readout electronics has a distributed architecture. Hit signals from the multi-gap resistive plate chamber (MRPC) are signaled as LVDS by front-end electronics (FEE) and are then sent to the back-end time digitizing system via long shield differential twisted pair cables. The ETOF digitizing system consists of two VME crates, each of which contains modules for time digitization, clock, trigger, fast control, etc. The time digitizing module (TDIG) of this prototype can support up to 72 electrical channels for hit information measurement. The fast control (FCTL) module can operate in barrel or endcap mode. The barrel FCTL fans out fast control signals from the trigger system to the endcap FCTLs, merges data from the endcaps and then transfers to the trigger system. Without modifying the barrel TOF (BTOF) structure, this time digitizing architecture benefits from improved ETOF performance without degrading the BTOF performance. Lab experiments show that the time resolution of this digitizing system can be lower than 20 ps, and the data throughput to the DAQ can be about 92 Mbps. Beam experiments show that the total time resolution can be lower than 45 ps.     

高精度时差提取技术在薄互层中的应用

声波测井中,对于砂一泥岩薄互层井段,由于地层声速变化及仪器分辨率低等原因导致不同接收器接收到的波形相关性差,用传统的时差-时间相关法往往不能得到稳定可靠的时差结果。对于数字声波测井而言,单个接收器的波形质量良好,针对这一现象,本文通过利用改进的探测首波波至的方法获得高精度的时差。将该方法应用到现场实例数据中,结果表明该方法有效的提高了地层首波时差的精度,清晰的刻画了薄互层特性。并且该方法基本不需要人工干预,在大部分情况下可以得到稳定可靠的结果。     

基于CPLD高精度恒流源技术的呼吸体积描记系统的设计

利用呼吸感应体积描记(RIP)技术测量呼吸参数已得到了越来越广泛的认可,针对人体呼吸运动引起传感线圈的电感量变化非常小(小于几百nH),一般系统难以保证精确性和适用性问题;硬件设计采用了高精度恒流源,锁相放大和自动增益控制放大电路,并详细分析了各部分电路的特性,包括在平静呼吸和用力呼吸模式下分别对14位测试者测量潮气量和呼吸频率,并且与德国耶格公司的肺功能仪所测量的结果对比;实验证明RIP系统在这两种模式下测量潮气量和呼吸频率等呼吸参数与速度描记仪存在显著的正相关关系,说明该系统工作良好、测量精确,操作简单、便于携带和低功耗,未来可以在临床上推广应用于长时间动态的呼吸监测。     

Two-parameter estimation with three-mode NOON state in a symmetric triple-well potential

We propose a scheme to realize two-parameter estimation via Bose–Einstein condensates confined in a symmetric triple-well potential. The three-mode NOON state is prepared adiabatically as the initial state. The two parameters to be estimated are the phase differences between the wells. The sensitivity of this estimation scheme is studied by comparing quantum and classical Fisher information matrices. As a result, we find an optimal particle number measurement method. Moreover, the precision of this estimation scheme means that the Heisenberg scaling behaves under the optimal measurement.     

New designed helical resonator to improve measurement accuracy of magic radio frequency

Based upon the new designed helical resonator, the resonant radio frequency (RF) for trapping ions can be consecutively adjusted in a large range (about 12 MHz to 29 MHz) with high Q-factors (above 300). We analyze the helical resonator with a lumped element circuit model and find that the theoretical results fit well with the experimental data. With our resonator system, the resonant frequency near magic RF frequency (where the scalar Stark shift and the second-order Doppler shift due to excess micromotion cancel each other) can be continuously changed at kHz level. For ⁸⁸Sr⁺ ion, compared to earlier results, the measurement accuracy of magic RF frequency can be improved by an order of magnitude upon rough calculation, and therefore the net micromotion frequency shifts can be further reduced. Also, the differential static scalar polarizability Δα₀ of clock transition can be experimentally measured more accurately.     

Determination of Pb,Zr, Ti,Sr, Cr,Nb and La in lead zirconate titanate ceramics by particle‐induced X‐ray emission

A particle‐induced X‐ray emission (PIXE) technique has been used in the determination of the principal components Pb, Zr and Ti and the substituting elements Sr, Cr, Nb and La in lead zirconate titanate ceramics. In general, precision of analysis was concentration dependent from each element under study. For Pb, precision varied between 0.13% and 0.16%, at higher concentration of 59.32–64.5%. It was around 6–9% for Sr, Cr and Nb at concentrations of 1% or lower. Particular attention was devoted to the estimation of the analysis trueness. With this purpose, three methods were applied: (1) comparison of PIXE and inductively coupled plasma optical emission spectrometry concentrations, (2) recovery study and (3) comparison with a laboratory standard. Trueness of analysis was around 100 ± 10% for the evaluated elements Pb, Zr, Ti, Sr and Cr. The expected stoichiometry and elemental composition homogeneity of a wide group of produced ceramics were confirmed by the PIXE technique. Copyright © 2012 John Wiley & Sons, Ltd.     

激光模场传递矩阵分析方法的精度控制

讨论激光模场的传递矩阵分析法,并对计算精度进行控制.结果表明,传递矩阵分析方法与传统的积分数值迭代法计算结果一致,只要合理控制计算精度,可以解决积分数值迭代法难于收敛的问题,满足激光谐振腔模场分析的实际要求.     

矩形槽内水体大幅晃动分析中截断误差影响范围判断方法探讨

液体大幅晃动是目前CFD研究中一个热点。在CFD中,偏微分方程离散所产生的截断误差是主要的误差来源,且与网格尺度密切相关。本文首先从理论上介绍了截断误差的产生过程,由此过程可知截断误差与物理粘性的作用具有类似性。以此概念为基础,根据液体晃动动力响应的特点提出了在液体大幅晃动分析中,如何通过对物理粘性系数的参数敏感性分析,判断截断误差的作用范围从而判断计算精度是否满足要求的方法,最后与现有试验资料进行对比校核,验证了该方法的实用性。     

Recent Progress with the SMILETRAP Penning Mass Spectrometer

The Penning trap mass spectrometer SMILETRAP has been considerably improved during the last two years. The helium pressure has been carefully stabilized and is now independent of irregular air pressure. The temperature of the hyperboloidal precision trap is stabilized to ±0.03°C. Remaining temperature instabilities are compensated by changes in the current of a warm coil surrounding the precision trap. The frequency synthesizer is now locked to GPS. This means that it is much easier to accurately measure resonances during several days. The improvements have demonstrated that in mass doublet measurements with an excitation time of 1 s it is possible to determine the mass of ions with q/A=1/2 at an uncertainty to a few times of 0.1 ppb, using selected rather than cooled ions. In routine measurements lasting for one day it is possible to reach a mass uncertainty of 1 ppb. The masses of the following particles and atoms have been measured with uncertainties in the region 0.3–2 ppb: p, ³H, ³He, ⁴He, ²²Ne, ²⁸Si, ³⁶Ar, ⁷⁶Ge, ⁷⁶Se, ⁸⁶Kr and ¹³³Cs. It has also been shown that though we are using a warm bore the trap pressure is sufficiently low to prevent electron capture from the rest gas for excitation times of 3 s and for ion charges as high as 50+. This revised version was published online in July 2006 with corrections to the Cover Date.