THEORY AND APPLICATIONS OF FREQUENCYMETRIC TITRATION

Theory on frequencymetric titration has been proposed based on equivalent circuit of piezoelectric quartz crystal (PQC) in liquid and oscillation equation of TTL-PQC oscillator, and the theoretical equation derived representing the frequency shift with respect to the solution conductivity. Practical examples of various types of titration are given in this paper.     

矿物中次显微金的电子显微术研究

利用透射电子显微象、电子衍射和X射线能量色散谱仪研究了黄铁矿、毒砂、石英等矿物中次显微金的赋存状态及其颗粒大小,扩大了寻找金矿床的范围为全矿的综合开采、选矿流程设计及提高金的回收率等方面提供了技术依据。     

火焰原子吸收法测定大豆、茶叶及合金中微量铁和锰

本文用ＦＡＡＳ法对大豆、茶叶及合金中的铁和锰进行研究［１－４］。根据实验结果，铁的变异系数为１．０～３．７％，回收率为９８～１０１％；锰的变异系数为２．４～３．５％，回收率９７～１０３％，均得到较为满意的结果，具有较好的实用价值。     

YDXL-Ⅲ87A压电晶体三向小力值传感器的研究

从机理，晶体切割，力电转换，结构优化，晶组构成，组序排列，装架技术，预 载原理，标定与使用等一系列理论与实际问题上，全面阐述了三向小力值传感器的原 理与研制的关键，给出了计算公式，并对实际使用过程中出现的一些问题给出解决办 法。     

微机电陀螺零点漂移数据滤波方法的研究

微机电石英音叉陀螺虽然有突出的优点，但也存在噪声比较大的缺点。普通的数字滤波方法通常会造成比较大的滞后，减小了系统的相位裕度，而且对截止频率以内的噪声不起作用。作者在对石英音叉陀螺零点漂移数据建立时间序列模型（AR模型）的基础上，采用卡尔曼滤波算法对石英音叉陀螺的漂移数据进行了处理。仿真实验表明，所采用的滤波方法合理有效。     

波长校准用低压石英汞灯驱动电源的研制

研制波长校准用低压石英汞灯电源,用于驱动汞灯起辉并维持稳态发光。电路由EMI滤波电路、桥式整流电路、LCC半桥谐振逆变电路、控制电路和保护电路5部分组成。采用系统建模与仿真验证电路的可行性并计算电路参数理论值,利用示波器和功率表验证电源输出参数,功率输出稳定性不大于0.03 W。根据紫外可见近红外分光光度计国防最高计量标准对研制的电源驱动汞灯的工作效果进行评价。结果表明,汞灯能够输出系列特征谱线,谱线相对强度稳定性不大于5.16%;汞灯工作3 h后,灯管外壳表面温度为43℃。该驱动电源的性能参数满足JJG112–2015《低压石英汞灯波长标准器检定规程》的要求。     

Phase Behavior of Methane-Pentane Mixture in Bulk and in Porous Media

The adiabatic calorimetry method is used to measure the isochoric heat capacity and the dew-bubble curves for the methane-normal pentane mixtures in bulk for three different mixture compositions of n-pentane. The near-critical behavior of the mixture heat capacity indicates that at low n-pentane concentrations, this system is close to the special point of the critical locus. The effect of porous medium has been investigated for one of the mixtures studied in bulk. It has been shown that in porous medium the essential shift of the dew-bubble curve takes place. In our opinion this shift is caused by the formation of wetting film on the surface of porous medium. The estimation of film thickness resulting from the data obtained yields the value 7–8 nm.     

Flocculation and rheology of kaolinite/quartz suspensions

Rheological properties of suspensions of Na-kaolinite and colloidal quartz (Min-U-Sil) at constant overall volume concentration of 2% are determined with a Weissenberg Rheogoniometer using a combined Couette and cone-and-plate geometry. The results are interpreted in terms of the flocculation behaviour of the constituent particles in the presence of high salt concentrations (0.1–0.75m NaCl) at pH 6, 7 and 8. In these chemical environments these suspensions are pseudoplastic for much of the range of mixture compositions becoming Newtonian for suspensions containing only quartz. These properties reflect the dominant influence of interactions between kaolinite particles on the flocculation behaviour of the mixture.Nomenclature a ₁, a₂ radii of spheres - A Hamaker constant - b radius of cylinder - C volumetric solids concentration - e ₀ electronic charge - H ₀ shortest distance between surfaces - I ionic strength - J collision frequency per unit volume - k Boltzmann constant - l length of cylinder - m number in eq. (2) - N particle number concentration - S (H ₀ + b)/b in eq. (4) - T absolute temperature - U electrophoretic mobility - V _A van der Waals attractive energy - V _R coulombic energy - V _T total energy of interaction - X H ₀/2a₁ in eq. (5) - Y a ₂/a₁ in eq. (5) - thickness of plate - shear rate - permittivity - zeta potential - k Debye-Hückel parameter - µ dynamic viscosity - µ _pl plastic viscosity - v valency of counter ion - shear stress - _B Bingham stress - ₁, ₂ dimensionless potentials - ₁, ₂ surface potentials