一种MEMS可调光衰减器性能测试及动态响应分析

一种基于微细电火花加工(EDM)技术的非硅基MEMS可调光衰减器,以电磁线圈驱动微反射镜.本文介绍该器件特性测试及动态响应分析,结果表明,驱动电压为0～8 V,工作范围0～35 dB,动态响应时间为2 ms,插入损耗小于0.8 dB,回波损耗小于－50.5 dB.     

Study of low momentum track reconstruction for the BESⅢ main drift chamber

In order to overcome the difficulty brought by the circling charged tracks with transverse momentum less than 120 MeV in the BESⅢ Main Drift Chamber （MDC）, a specialized method called TCurlFinder was developed. This tracking method focuses on the charged track reconstruction under 120 MeV and possesses a special mechanism to reject background noise hits. The performance of the package has been carefully checked and tuned by both Monte Carlo data and real data. The study shows that this tracking method could obviously enhance the reconstruction efficiency in the low transverse momentum region, providing physics analysis with more and reliable data.     

浅谈电声领域专利的撰写技巧

针对电声领域就如何提高专利申请文件的撰写质量进行了研究和分析,结合电声领域的特点,对权利要求和说明书的撰写进行了细致的分析说明,对电声领域中专利审查的特别规定通过案例进行了研究,并介绍了电声领域专利申请中的一些注意事项.     

Decay vertex reconstruction and 3-dimensional lifetime determination at BESⅢ

This paper focuses mainly on the vertex reconstruction of resonance particles with a relatively long lifetime such as Ks^0, A, as well as on lifetime measurements using a 3-dimensional fit. The kinematic constraints between the production and decay vertices and the decay vertex fitting algorithm based on the least squares method are both presented. Reconstruction efficiencies including experimental resolutions are discussed. The results and systematic errors are calculated based on a Monte Carlo simulation.     

Track reconstruction in the BESⅢ muon counter

The reconstruction algorithm for BESⅢ Muon Counter, MucRecAlg, is developed with the objectoriented language C＋＋ in BESⅢ offine software environment. MucRecAlg consists of the following functions：to find track seeds either from extrapolation of tracks in the main drift chamber or from the fired strips in muon counter, to select fired strips associated to the candidate tracks, to fit the candidate tracks with a linear or quadratic function and to calculate other parameters of the tracks for muon identification. Monte Carlo samples are generated to check the performance of the reconstruction package, such as reconstruction effciency, muon remaining rate and pion rejection rate, etc. The preliminary results show that the pion rejection rate is around 3%—4% while the muon remaining rate is better than 90% in 0.4—1.6 GeV/c momentum region, which meets the requirement as shown in the design report.     

非硅基底1×4微机电系统光开关

设计研制了一种小体积、低成本、可扩展的低电压非硅基底 1× 4微机电系统光开关。开关单元由电磁驱动 ,微反射镜绕直径 10 0 μm转轴转动 ,驱动电压为 5V ,开关时间小于 2ms,插入损耗小于 0 .84dB ,具有断电自锁功能。器件构造工艺采用微细电火花加工技术。用有限元法分析受力和磁场 ,进行结构优化设计 ,并着重介绍开关的实现及性能     

BESIII barrel time-of-flight （TOF） calibration using cosmic ray data

The principle of the method for the BESIII TOF calibration using cosmic ray data without magnetic field are reported in this paper. After applying calibration constants, the single-end readout time resolution could reach about 150 ps, and the time resolution for one layer is achieved to be about 110 ps. The paper also described the extraction scheme for the event start time of cosmic events.     

基于条件共生概率矩阵的移位JPEG双压缩检测

针对合成JPEG图像的小区域移位JPEG双压缩(SD-JPEG压缩)篡改问题,提出一种基于条件共生概率矩阵(CCPM)的SD-JPEG压缩篡改检测算法。为了减小图像内容的影响,增强SD-JPEG压缩效应,首先对JPEG量化的离散余弦变换(DCT)系数的幅度矩阵进行水平、垂直、主对角和副对角4个方向差分和阈值化处理,然后使用CCPM对这4个阈值化的差分矩阵进行建模,选取CCPM的元素作为特征数据,并用主分量分析(PCA)对其降维处理,最后通过支持向量机(SVM)技术判决图像块是否经过SD-JPEG压缩。实验结果验证了本文算法的有效性。     

快速消解–原子荧光光谱法测定大米中总砷

建立快速消解–原子荧光光谱测定大米中砷含量的方法。以硫脲、抗坏血酸的质量浓度均为10 g/L的硫脲–抗坏血酸–盐酸溶液为掩蔽还原剂、10 g/L硼氢化钾溶液溶液为还原剂、盐酸溶液(5+95)为载流,在优化的仪器工作条件下,采用原子荧光光谱法测定,用标准曲线法定量。砷的质量浓度在0.00～10.00 g/L范围内与荧光强度具有良好的线性关系,相关系数为0.999 9,方法检出限为0.7 ng/g。用所建方法对大米样品进行测定,加标回收率为92.1%～104.9%,测定结果的相对标准偏差为0.27%～2.35%(n=5);对两种大米有证标准物质进行测定,测定值均在标准值不确定度范围内,相对误差分别为6.7%和8.3%。该方法精密度、准确度均满足分析要求。     

缪子物理实验现状及发展前景

寻找超出标准模型的新物理是当前粒子物理学最重要的任务之一.缪子物理实验,包括带电轻子味道破坏,缪子反常磁矩和电偶极矩,缪子素到反缪子素转换等是高强度前沿新物理研究的热点领域.文章介绍了国际上在这一领域开展实验的现状和展望,特别的,介绍了未来在中国开展相关实验的前景.