基于液芯柱透镜实现透明液体质量分数的测量

通过测量基于聚二甲基硅氧烷(PDMS)基片的液芯柱透镜的后焦距,可实现液体折射率的快速测量;根据液体质量分数与折射率之间的良好线性关系,准确计算出待测透明液体的质量分数.搭建光学测量系统,以NaCl溶液和蔗糖溶液为例,构建了液体质量分数与液体折射率的关系模型,实现了溶液质量分数的测量,并对其测量不确定度进行了分析.基于PDMS基片的液芯柱透镜对注入其中的液体折射率的最小分辨能力优于0.000 2 RIU,质量分数测量不确定度可控制在0.12%以内.该测量方法适用于微量液体折射率及质量分数的测量.     

最大气泡压力法测液体表面张力系数的改进

对最大气泡压力法测定液体表面张力系数的实验原理、方法及仪器进行了研究,提出用螺旋活塞定量加压控制气泡的生成速度;用扩散硅气体压力传感器测量压强,测得值数字显示;用双毛细管制作实验探头,消除了毛细管插入液体一定深度产生的静压强及待测液体密度等对计算液体表面张力系数的影响,提高了液体表面张力系数的测量速度和精度.     

液体密度仪的设计与制作

依据物理原理,采用传感器技术设计与制作的液体密度仪可实现自动、连续测量待测液体的密度。该装置主要是由盛装待测液容器、信号采集、信号处理、信号显示等功能组成。采用压力传感器采集待测液的重量,超声波测距模块采集待测液体的高度;以STM32单片机为控制核心,对采集到的信号进行数据处理,并将结果传送至显示器,实时显示测量结果。具有快捷、精确、实时测量的优点,在教学科研方面有一定实用价值。     

用秒表测定液体的密度

介绍了利用秒表测定液体密度的方法.该方法通过秒表测量漂浮在待测液体中做简谐运动的试管的运动周期,经计算即可得到待测液体的密度.与传统测定液体密度的实验相比,该方法设计巧妙,操作简单.     

测量物质密度的两种特殊方法

测量物质密度的常规方法有:一是对规则固体而言,用测长工具测体积,用天平称质量,再根据密度的定义求得;二是对不规则的固体用流体静力法进行测量,流体静力法对液体的密度测量同样适用;三是用比重瓶法测液体和固体的密度.而根据液体内部压强特点利用U型连通器或W型连通器测液体的密度和根据浮力的原理利用悬浮法测固体的密度的方法则不多见,而这种构思新颖、设计巧妙的方法能解决一些特殊物质的密度的测量.下面详细介绍这两种测密度的方法.     

蒸发器支撑板板孔精密测量系统

建立了蒸发器支撑板板孔精密测量系统,并提出了基于边缘约束条件的轮廓参量测量方法.首先采用图像处理技术将待测目标转化为二维离散坐标点,计算其最小外接矩形并对轮廓进行预定位;然后将轮廓分割成相互重合的"扩展邻域轮廓",建立以曲率角为原则的边缘约束算法对各轮廓段精确定界,实现对轮廓参量的精密测量.实验和误差分析表明,该系统测量准确度优于0.02mm,对具有复杂轮廓的零件参量测量有参考价值.     

音叉共振式液体密度测量实验的设计与实现

在原有的DH4615型音叉受迫振动与共振实验仪的基础上,设计了液体密度测量传感装置,通过实验数据测量、定标,对水、乙醇、汽油等液体通过测量谐振频率求得待测液体的密度,测量精度符合实验要求.     

利用硅压阻式力敏传感器测定液体膨胀系数

根据液体膨胀系数与温度、密度相关的性质,利用硅压阻式力敏传感器设计了测定液体膨胀系数实验.通过测量不同温度下的输出电压,计算液体的膨胀系数,实现了对非电学量力的电测.     

干涉法测量液体膨胀系数的讨论

液体的折射率和液体的密度有直接关系,液体密度又与温度有关,根据已有关于透明介质的折射率公式,可得液体的膨胀系数的测量方法.迈克耳孙干涉法是测量液体折射率的温度系数的简捷的手段.用此方法得出了液体的膨胀系数,进而讨论了关于液体折射率的2个不同公式的精确程度.     

液体粘滞系数与温度关系实验及曲线拟合

本文介绍一种可以调节温度,且恒温较好的落球法测量液体粘滞系数的装置,用此装置可以较精确地测量不同温度时液体的粘滞系数值。由实验测量得出的粘滞系数与温度的关系,将通过三种基本函数回归分析,计算出衡量各回归曲线回归程度好坏的标准差,从而判定哪一函数最适合液体粘滞系数随温度变化的实际规律。本文还用离散的实验数据点代入N次多项式,用最小二乘法确定其系数,从而求得待测液体粘滞系数与温度关系的曲线方程.此例提供了一种如何用统计手段确定待测数据特性的方法。     

一套基于六面顶高压装置的静水压高频介电测试系统

 以一套6×14 400 kN六面顶高压装置和一台Agilent 4294A精密阻抗分析仪为主体,建立了一套静水压高频介电实时测试系统。通过固体传压介质预成型方法,解决了液体测试腔在固体传压介质中的密封以及包括4根微同轴电缆在内的多根测量导线引出密封边问题,将常压下通用的四同轴阻抗谱测试技术引入了高压研究。液体测试腔容积可达(Φ13×15) mm³,可同时容纳10 mm×10 mm样品、高频测试夹具、温度与压力传感器、加热装置,以及包括4根外径为1.6 mm、特性阻抗为50 Ω微同轴电缆在内的16根引线,进行室温至300 ℃、常压至3 GPa 静水压力、测试频率40 Hz~5 MHz范围材料的四线阻抗谱测量,实验误差小于3%。利用这套装置观察了室温下,BaTiO₃单晶在约2.6 GPa静水压力下的压致铁电-顺电相变。     

Imaging of internal stress around a mineral inclusion in a sapphire crystal: application of micro‐Raman and photoluminescence spectroscopy

We developed a micro‐Raman and photoluminescence imaging technique for visualizing the internal stress fields in a sapphire crystal. The technique was applied to an Australian sapphire gemstone with a zircon inclusion. Considering piezospectroscopic effects on Raman and photoluminescence spectra, the Raman shifts of sapphire around the zircon inclusion were converted to hydrostatic pressure and deviatoric components of stress tensor. The internal stress was highly concentrated at the tips of the zircon crystal, where the deviatoric stress and the hydrostatic pressure component reached 700 and 470 MPa, respectively. Generation of compressive stress on the crystal surface of zircon can be explained by the difference in thermal expansion coefficients and elastic constants between sapphire and zircon. In general, internal stress fields induced by mineral inclusions reflect the pressure and temperature conditions at which the host sapphire gemstones were crystallized. Thus, the present technique can be utilized to identify the origin of gemstones. Copyright © 2012 John Wiley & Sons, Ltd.     

The structural, elastic and thermodynamic properties of thorium tetraboride

The structural, elastic and thermodynamic properties of thorium tetraboride (ThB₄) have been investigated by using first-principles plane-wave pseudopotential density functional theory with generalized gradient approximation. The behaviors of structural parameters under 0-70 GPa hydrostatic pressure are studied by means of Broyden, Fletcher, Goldfarb, and Shanno (BFGS) geometry optimization scheme. By using the stress-strain method, single crystal elastic constants are calculated to test the mechanical stability of the crystal structure and to determine mechanical properties such as bulk modulus at each pressure. However, in order to study the thermodynamic properties of ThB₄, the quasi-harmonic Debye model is used. Then, the dependencies of bulk modulus, heat capacities, thermal expansions, Grüneisen parameters and Debye temperatures on the temperature and pressure are obtained in the whole pressure range 0-70 GPa and temperature range 0-1500 K.     

ZnO纳米/微米结构传感器对乙醇气敏性研究

采用化学气相法分别在石英舟内表面和单晶硅衬底上制备了ZnO微米片、纳米线、微米四足体以及微米球4种结构,并制作了相应的气敏传感器。扫描电子显微镜、气敏测试仪等结果显示：合成的ZnO纳米/微米结构尺寸在200 nm~100 μm之间,传感器最佳工作电流区间为120~130 mA,其中微米四足体制备的传感器灵敏度高达127,展现出优异的气敏特性。在4种结构中,微米四足体材料内部的V_O缺陷含量最高,结合气敏测试与荧光光谱结果,我们认为材料内部的V_O缺陷含量是影响材料气敏特性的最重要因素。     

High pressure cell for neutron diffraction investigations

Abstract

The design of a titanium-zirconium clamped cylinder-piston type pressure cell for neutron diffraction investigations under hydrostatic pressure up to 10 kbars without supports is described. It is the first time that Freon-11 has been used as a hydrostatic pressure transmitting medium. The following results carried out at the room temperature are presented: the discovery of the transition from I to 111 phase in a LiKSO₄ single crystal and the results of the investigation on the influence of pressure upon the structure of the YBaCuO HTSC obtained by means of the powder diffraction method.     

高压下单晶LiF的光学及热力学性质的密度泛函理论研究

采用平面波赝势密度泛函方法,对单晶氟化锂(LiF)在0~500 GPa静水压下的光学性质进行了理论研究,并利用Vinet状态方程和准简谐Debye模型得到了其热力学性质.理论计算结果表明单晶氟化锂(LiF)在0~500 GPa静水压范围内具有良好的透明性,吸收波段随压强的增加而出现了蓝移.计算所得晶格常数、体积模量及其对压强的一阶导数与实验值相符合.     

Optical fiber sensor for temperature measurement based on Silicon thermo-optics effect

A temperature sensor based on the thermo-optics effect of single crystal silicon diaphragm was proposed and studied. The temperature measurement mechanism by using single crystal silicon diaphragm was theoretically analyzed and found the relation between temperature measurement range and the thickness of single crystal diaphragm. It was found that when the temperature changed from 20 °C to 48 °C, the reflected resonant peak wavelength was shifted which was detected by using the dual-wavelength signal demodulation method. Experimental results for temperature measurement demonstrated reasonable linearity and repeatability, related linear regression coefficient of the experimental result is 99.94%. The study would be of utility value for the design and fabrication of silicon-based sensors which were used to measure pressure or the other physical quantities.     

基于布里渊动态光栅的高灵敏度静压力传感器设计

设计了一种新型边孔型保偏光子晶体光纤,在包层中对称地引入两个大空气孔,纤芯区域与大空气孔之间仅有一层小空气孔。由平面应变假设将该模型进行二维简化,利用有限元法对该光纤的二维模型进行数值分析,通过计算不同温度和静压力下的双折射频移以研究其温度和静压力传感特性。研究表明,在较大静压力和温度范围内,该保偏光子晶体光纤无需掺杂任何应力材料就可以实现?2.1353 GHz/MPa的静压力灵敏度且具有温度不敏感性,其温度灵敏度仅为+0.1542 MHz/℃。另外,还对该光子晶体光纤的光学特性进行了分析,其满足单模传输条件、具有较小的限制性损耗和较大的有效模场面积。由于具有体积小、与其他光纤兼容度强、静压力灵敏度高、温度不敏感的特性,其在温度变化不定、静压力改变区间较大的环境中静压力精确测量的优势比较明显,较好的光学特性使其在油井、土木的监测应用等方面有着重要参考价值。     

Density measurements of liquids at high pressure: Modifications to the sink/float method by using composite spheres,and application to Fe-10wt%S

Abstract

We describe a new modification of the sink/float method of determining the density of molten materials under high pressure, and apply it to liquid Fe-10wt%hS. The modification is based on the use of composite spheres made of a dense, metallic core and a sapphire or ruby mantle. Composite spheres permit tailored densities for use in a variety of liquid compositions. The inert mantle also prevents chemical reaction with molten metallic samples. The pressure dependence of the density of liquid Fe-10wt%S at 1773 K, determined by bracketing, using composite spheres, is compared with the equation of state of Fe-10wt%S obtained by Sanloup et al. (2000), using X-ray absorption.     

X‐ray reflectivity measurements of liquid/solid interfaces under high hydrostatic pressure conditions

A high‐pressure cell for in situ X‐ray reflectivity measurements of liquid/solid interfaces at hydrostatic pressures up to 500 MPa (5 kbar), a pressure regime that is particularly important for the study of protein unfolding, is presented. The original set‐up of this hydrostatic high‐pressure cell is discussed and its unique properties are demonstrated by the investigation of pressure‐induced adsorption of the protein lysozyme onto hydrophobic silicon wafers. The presented results emphasize the enormous potential of X‐ray reflectivity studies under high hydrostatic pressure conditions for the in situ investigation of adsorption phenomena in biological systems.