A study on the applications of the acoustic design sensitivity analysis of vibrating bodies

The determination of the sensitivity of the acoustical characteristics of vibrating systems with respect to the variation of the design parameters predicting these characteristics is a necessary and important step of the acoustic design and optimization process. Acoustic design sensitivity analysis includes the computation and evaluation of the sensitivity information required for this procedure. In this study, a boundary element code performing the sensitivity analysis of the acoustic pressure by using the matrix sensitivities with respect to different design variables has been developed. The effect of the precision of boundary element discretization on the acoustic pressure sensitivity is examined via this code. The formulation is applied to a multi-source system and the dimension sensitivity analysis of near field pressures of two-dilating-spherical source is performed. The last application is devoted to a real sound source: a washing machine sitting on the floor. Sensitivity of the field pressures to the machine’s dimensions (size), surface velocity and frequency is examined on the bases of the boundary element model of the machine and half-space condition. The impacts of these variables are compared; and a limiting speed for the machine responding both the acoustical and operational requirements is determined.     

Apparatus for High-Resolution Solid Hydrogen Matrix Isolation Spectroscopy and Its Application

Apparatus integrating a Fourier transform-infrared (FT-IR) spectrometer and a mid-infrared difference frequency generation (DFG) laser spectrometer was built for the study of the matrix isolation spectrum in solid molecular hydrogen. A 3-cm-long molecular hydrogen crystal was grown in a liquid-helium Dewar, and its infrared absorption spectrum in the 1-5 μm region was recorded to test the system. The W₀(0) (ν=0←0, J=6←0) line around 2410 cm⁻¹ of solid hydrogen was investigated with the DFG laser spectroscopy. High-resolution matrix isolation spectrum of CO² co-deposited with hydrogen on a BaF₂ cold plate at liquid-helium temperature was studied.     

关于曲线积分中值定理“中间点”的一个一般性结果

讨论了第一类曲线积分中值定理“中间点”的渐近性质,得到了更具一般性的新结果.     

Simultaneous determination of cloramphenicol, salicylic acid and resorcinol by capillary zone electrophoresis and its application to pharmaceutical dosage forms

This study demonstrates the separation of active ingredients in acne formulations (salicylic acid, cloramphenicol and resorcinol in presence of azulene) by capillary zone electrophoresis. Factors affecting their separations were the buffer pH and concentration, applied voltage, sample preparation, and presence of additives. Optimun results were obtained with a 50 mM sodium tetraborate-50 mM sodium phosphate, pH 9.0. The carrier electrolyte gave baseline separation with good resolution, short migration times (<6 min), great reproducibility and accuracy. Calibration plots were linear over at least three orders of magnitude of analyte concentrations, the lower limits of detection being within the range 0.39-1.25 μg ml⁻¹. The procedure was fast and reliable and commercial pharmaceuticals could be analysed without prior sample clean-up procedure.     

On existence and asymptotic stability of solutions of a nonlinear integral equation

We prove an existence theorem for a nonlinear integral equation being a Volterra counterpart of an integral equation arising in the traffic theory. The method used in the proof allows us to obtain additional characterization in terms of asymptotic stability of solutions of an equation in question.     

多巴酚丁胺的流动注射化学发光法测定

在盐酸介质中 ,高锰酸钾可氧化多巴酚丁胺产生化学发光 ,甲醛对该反应有较强的增敏作用 ,据此 ,建立了流动注射化学发光法测定多巴酚丁胺的方法 ;方法的线性范围为0.1～100mg·L -1,检出限为0.07mg·L -1 ,相对标准偏差为1.2 %(n=11,ρ=1.0mg·L -1) ;该法用于药物中多巴酚丁胺含量的测定 ,结果令人满意。     

Whole-field determination of isoclinic parameter by five-step color phase shifting and its error analysis

Combining color imaging with phase shifting, a technique named five-step color phase shifting is presented to determine the whole-field isoclinic parameter. Relevant theory is derived and explicit conditions for directly determining the isoclinic parameter in the range of [0,π/2] are given. The unloaded light intensity of the model is systematically studied. A color camera recorded five isoclinic images coupled with isochromatics from a plane polariscope with five different settings, respectively. Experiments have been carried out with a circular disk under diametral compression and errors have been analyzed and estimated. This technique utilizes white light, which avoids undefined isoclinics near the locations where the isochromatics exist and will have active effect on experimental stress analysis and structural strength design.     

Comparison of Several Calibration Procedures for Glass Electrodes in Proton Concentration

Several reported procedures for calibrating glass electrodes in proton concentration are compared. Some recommendations for non-experts are also given. The examined procedures can be classified into two broad categories, namely: those based on direct potential difference measurements of solutions of known proton concentration and those that use one or several pH standards to calibrate the electrode and subsequently measure the pH of solutions containing known proton concentrations. With a single buffer, the two types of procedures lead to equivalent results. However, if two pH buffers are used, the slope of the calibration graph in proton concentration will differ from the real electrode slope to an extent proportional to the difference between the liquid junction potentials of the two buffers. Therefore, any other method is preferable under these circumstances.     

SiGe (Ge-dot) heterojunction phototransistors for efficient light detection at 1.3–1.55 μm

The aim of this work is to develop a Si/SiGe HBT-type phototransistor with several Ge dot layers incorporated in the collector, in order to obtain improved light detectivity at 1.3–1.55 μm. The MBE grown HBT detectors are of n–p–n type and based on a multilayer structure containing 10 Ge-dot layers (8 ML in each layer, separated by 60 nm Si spacer) in the base-collector junction. The transistors were processed for normal incidence or with waveguide geometry where the light is coupled through the edge of the sample. The measured breakdown voltage, BV_ceo, was about 6 V. Compared to a p–i–n reference photodiode with the same dot layer structure, photoconductivity measurements show that the responsivity is improved by a factor of 60 for normal incidence at 1.3 μm. When the light is coupled through the edge of the device, the detectivity is even further enhanced. The measured photo-responsivity is more than 100 and 5 mA/W at 1.3 and 1.55 μm, respectively.