基于核电子学实验教学用的模数变换电路研制

介绍了一种基于核电子学实验教学用的模数变换电路的研制。在设计中,以单极型、16位、采样率为500k Hz,微功耗采样模数转换器ADS8322为核心,将采样保持电路输出的模拟信号转换为数字信号,通过发光二极管显示变换出的结果,在核物理实验教学过程中便于学生观察模数转换结果。在PCB板设计时在板正面绘制出了电路原理图,理解电路原理及构成。该电路也可以配合逻辑控制模块以及PC软件组成多道分析系统测量射线能谱。     

机液控制可变径扶正器的结构及应用研究

在定向钻井中，造斜、稳斜及降斜是主要的工艺过程．目前在实际钻井时，实现这几个工艺过程，需要通过起下钻具，改变钻具组合来完成，这样就使得钻井作业辅助时间增长．本文将介绍一种机液控制的可变径扶正器．该扶正器的特点是工作时直径可调节，因而，不需要起下钻就可实现钻具组合的改变，从而完成造斜，稳斜及降伴等工艺过程．使用该扶正器将大大节约钻井成本，提高钻进速度．给出了这种可变径扶正器的主要结构设计、工作原理、主要的水力计算方法及简单的应用操作．通过计算分析可知：该扶正器可在任意深度的井段内实现变径，从而完成特殊作业要求．     

推铅球握持球技术常见错误动作的产生原因与纠正方法

本文采用观察，调查，记录等方法，现场观察，调查，统计425名大，中学学生推铅球握法和持球中的错误动作，并对结果进行统计学处理，结果表明，握法与持球的错误在中学生与大学生中约占总人数的三分之二，具有普遍性，女生更甚于男生10－19个百分点，这种现象应引起广大体育工作者，特别是大，中学体育教师的深思，本文运用运动生物力学的基本原理，进行技术分析与正误对比，提出握法中最常见的错误动作和纠正错误的方法。     

Single-trial decoding of imagined grip force parameters involving the right or left hand based on movement-related cortical potentials

Time–domain feature representation for imagined grip force movement-related cortical potentials(MRCP)of the right or left hand and the decoding of imagined grip force parameters based on electroencephalogram(EEG)activity recorded during a single trial were here investigated.EEG signals were acquired from eleven healthy subjects during four different imagined tasks performed with the right or left hand.Subjects were instructed to execute imagined grip movement at two different levels of force.Each task was executed 60 times in random order.The imagined grip force MRCP of the right or left hand was analyzed by superposition and averaging technology,a single-trial extraction method,analysis of variance(ANOVA),and multiple comparisons.Significantly different features were observed among different imagined grip force tasks.These differences were used to decode imagined grip force parameters using Fisher linear discrimination analysis based on kernel function(k-FLDA)and support vector machine(SVM).Under the proposed experimental paradigm,the study showed that MRCP may characterize the dynamic processing that takes place in the brain during the planning,execution,and precision of a given imagined grip force task.This means that features related to MRCP can be used to decode imagined grip force parameters based on EEG.ANOVA and multiple comparisons of time–domain features for MRCP showed that movement-monitoring potentials(MMP)and specific interval(0–150 ms)average potentials to be significantly different among 4 different imagined grip force tasks.The minimum peak negativity differed significantly between high and low amplitude grip force.Identification of the 4different imagined grip force tasks based on MMP was performed using k-FLDA and SVM,and the average misclassification rates of 27%±5%and 24%±4%across 11 subjects were achieved respectively.The minimum misclassification rate was 15%,and the average minimum misclassification rate across 11 subjects was24%±4.5%.This investigation indicates that imagined grip force MRCP may encode imagined grip force parameters.Single-trial decoding of imagined grip force parameters based on MRCP may be feasible.The study may provide some additional and fine control instructions for brain–computer interfaces.     

Characterizing different types of black fountain pen ink using the chemical approach

Fountain pen ink contains dyes, pigments, or nanoparticles as colorants; water and ethylene glycol or an organic solvent as the vehicle. The dyes in fountain pen ink are usually negatively charged acid dyes. In this study, various types of black fountain pen ink (5 dye-based and 5 nanoparticle-based) were investigated by ultraviolet–visible (UV–Vis) absorption spectroscopy, Ion Pair High Performance Liquid Chromatography Diode-Array Detector (IP-HPLC-DAD), Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS), and Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry (LC-Q/TOF-MS) analysis. UV–Vis spectroscopy of fountain pen ink samples showed different profiles despite their similar color. MALDI-TOF-MS analyses successfully differentiated 10 of the inks. Nanoparticle-based ink, which is usually darker than dye-based ink, showed the same UV absorption at 240 nm. The use of LC-Q/TOF-MS, however, allowed the 5 dye-based fountain pen ink samples to be differentiated from one another. On the basis of the combined results of all analytical methods mentioned above, the discriminating power values were 0.71–1.00. Among them, MALDI-TOF-MS could successfully distinguish fountain pen ink samples with similar black colors and provide an easy analytical approach for the differentiation and identification of various types of fountain pens.     

超高效液相色谱法测定香型中性笔墨水中10种PAEs

建立超高效液相色谱–二极管阵列检测器测定香型中性笔墨水中邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二正丙酯(DPP)、邻苯二甲酸丁基苄酯(BBP)、邻苯二甲酸二正丁酯(DBP)、邻苯二甲酸二正戊酯(DAP)、邻苯二甲酸二环己酯(DCHP)、邻苯二甲酸二正己酯(DHP)、邻苯二甲酸二(2-乙基己基)酯(DEHP)和邻苯二甲酸二正辛酯(DNOP)10种邻苯二甲酸酯(PAEs)的方法。样品采用甲醇涡旋超声提取,色谱柱为Waters ACQUITY UPLC BEH C_(18)柱(100 mm×2.1 mm,1.7μm),以乙腈–水为流动相进行梯度洗脱,用PDA检测器检测,10 min内完成10种邻苯二甲酸酯的检测。10种邻苯二甲酸酯的质量浓度在5.0~200.0 mg/L范围内与其色谱峰面积呈良好的线性关系,线性相关系数均大于0.999,检出限为3.2~4.0 mg/kg;在高低两个添加水平下,10种邻苯二甲酸酯的回收率为96.3%~104.1%,测定结果相对标准偏差为0.1%~2.9%(n=6)。该方法样品处理简单,提取效率高,分离效果好,且灵敏度高,能快速准确测定香型中性笔墨水中10种邻苯二甲酸酯。     

复合材料加筋板连接剪切性能试验模拟

建立了带泡沫加筋的复合材料层合板连接件及试验夹具模型,用MSC.Nastran进行非线性有限元分析,模拟加筋层合板剪切性能试验,分析试验件过渡段和夹具刚度参数对剪切试验结果的影响,结果表明,考核区的应力随着夹具刚度及过渡段铺层的增加而减小,当夹具钢片厚度增大到15mm,过渡段铺层增加到考核区铺层的7倍时,考核区应力值较为稳定,可以作为工程试验夹具及过渡段设计的参考.     

10位100MHz采样保持电路设计

设计了一种适用于10位100MHz的流水线模数转换器的采样保持电路.利用SMIC0.13μmCMOS工艺,设计了一个直流增益为87.6dB的全差分自举增益放大器,其功耗仅7.2mW,且达到0.05%精度的响应时间小于4ns.在采样时钟频率为100MHz,输入信号频率为10MHz时,该采样保持电路的无杂散动态范围(SFDR)为80.7dB.     

FPGA的可靠时钟设计方案

对于现场可编程门阵列(FPGA)常见的6种时钟设计,根据建立时间和保持时间的要求,按照同步设计原则,分别给出可靠的时钟设计方案.利用这些方案来设计FPGA的时钟,可以更容易完成FPGA的项目设计,使得FPGA系统更稳定、更可靠.     

多种谱学方法研究蓝色签字笔墨水

运用傅里叶变换红外光谱、显微激光拉曼光谱以及紫外-可见光谱仪等多种光谱学手段测定了纸张上蓝色签字笔墨水的光谱,并根据吸收峰的差异对收集到的28种不同品牌、系列的蓝色签字笔进行了分类。同时还结合热重-质谱联用研究了人为老化过程中纸张上签字笔墨水成分的变化。讨论了上述谱学方法在分析鉴别纸张上蓝色签字笔墨水种类及成分的优劣,以及在研究相对书写时间和绝对书写时间中的潜在应用。