石英晶体板非线性高频振动的拓展伽辽金法分析

针对考虑几何和材料非线性的石英晶体板厚度剪切振动和弯曲振动的方程组,利用扩展伽辽金法对该方程组进行转化和求解,分别获得了强烈耦合的厚度剪切振动模态和弯曲振动模态的频率响应关系,绘制了不同振幅比和不同驱动电压影响下的频率响应曲线图。数值计算结果表明可以选取石英晶片的最佳长厚比尺寸来避免两种模态的强烈耦合。驱动电压的变化将引起石英晶体谐振器厚度剪切振动频率的明显改变,必须将振动频率的漂移值控制在常用压电声波器件的允许值之内。扩展伽辽金法对石英晶体板非线性振动方程组的求解为非线性有限元分析和偏场效应分析奠定了基础。     

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.     

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。     

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     

Validation of quartz crystal rheometry in the megahertz frequency regime

The utility of the quartz crystal microbalance (QCM) as a high‐frequency rheometer operating at 15 MHz was demonstrated. High‐frequency data obtained from a series of rubbery materials were compared with results obtained from traditional dynamic mechanical analysis (DMA) at much lower frequencies. The high‐frequency data enable meaningful shift factors to be obtained at temperatures much further above glass‐transition temperature (T _g) than would otherwise be possible, giving a more complete picture of the temperature dependence of the viscoelastic properties. The QCM can also be used to quantify mass uptake and changes in viscoelastic properties during sample oxidation. The viscoelastic response spanning the full range of behaviors from the rubber to glassy regimes was found to fit well with a six‐element model consisting of three power‐law springpot elements. One of these elements is particularly sensitive to the behavior in the transition regime where the phase angle is maximized. The value of this quantity is obtained from the maximum phase angle, which can be obtained from a temperature sweep at fixed frequency, proving a means for more detailed frequency‐dependent rheometric information to be obtained from a fixed‐frequency measurement at a range of temperatures. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1246–1254     

Density effects of heavy-ion stopping power in high temperature matter

Abstract

The stopping power and range for Xe ions in high temperature matter (partially ionized plasmas) have been calculated using the dielectric response function method. Calculations have been made for a target matter Al (Z = 13) over a wide range of temperatures and densities considering a finite temperature model. The stopping powers obtained have smaller values in comparison with those of a zero temperature model. The stopping power strongly depends on the density and temperature of the target material, and the projectile ion energy.     

Kurze Originalmitteilungen Ein neues Lanthan-140-Generatorsystem

Neben ihrer breiten Anwendung in der Nuklearmedizin gewinnen Radionuklidgeneratoren zunehmend auch für die verfahrensctechnische Forsehung Bedeutung. Es konnte gezeigt warden, daß die Generatorsysteme ⁹⁹Mo/^99mTe und ¹¹³Sn/^113mI für zahlreiche Untersuchungen von Transportund Mischvorgängen in technischen Anlagen genutzt warden könnea [1, 2].

Der Radionuklidgenerator ¹¹⁰Ba/¹¹⁰La hat für den Einsatz in der Technik günstigere Eigenschaftcn als die für die Nuklearmedizin entwickelten Generatoren. Insbesondere für die Untersuchung der Materialtransportvorgänge in Polykondensationsreaktoren der Chemiefaserindustrie hat sich ein Lanthan-140-Generator gut bewährt, der mit Tributylphosphat (gesättigt mit 13 N HN03) als Elutionsmittel arbeitet [3, 4].     

Recrystallization processes in snte thin films implanted with the nobel gas ions (Kr,Xe)

Abstract

The results of investigation of the quasi-Cherenkov (parametric) X-ray emission of 4.5 GeV electrons in diamond and quartz crystals are presented. A noticeable increase in X-ray photons yield has been observed under the influence of external factors (acoustic waves, temperature gradient).     

Signal Enhancement using A Swellable Polymer TSM Acoustic Wave Sensor Coating

ABSTRACT

The generation of large changes in the crystal frequency is a highly sought-after goal in designing a successful thickness-shear mode (TSM) acoustic wave sensor application. We examined the potential for modulating the mass loading and viscoelastic properties of a swellable polymeric coating to achieve this goal. Using a 10 MHz AT-cut crystal with an immobilized coating of a styrene-divinylbenzene copolymer, a high molecular weight target analyte with complementary ionic and molecular binding properties was selected. Injection of the antibiotic cefoperazone in a sodium acetate buffer generated exceptionally large changes in frequency, in the range 500 - 5000 Hz. The rate of change in frequency is proportional to the analytical concentration. A multi-step regeneration protocol allows the coating to be reused multiple times. These results suggest that TSM sensor sensitivities can be significantly enhanced for selected analytes by the judicious selection of an appropriate swellable polymer coating.