Investigations of uncertainties from hot water flowmeters using laser Doppler velocimetry

Electromagnetic flowmeters will be used as working standards for determining volumetric flowrates for hot water. Flowmeters for hot water can be calibrated by the well-known mass-time method only up to 100°C. But the district heat suppliers are greatly interested in flowrate measurements at higher temperatures in order to exactly calculate the delivered heat energy. The described one-point relative method using LDV is a time-saving procedure and allows the determination of the metrological performance of flowmeters as a function of flowrate and temperature above 100°C. The relative uncertainties in the determination of the flowrates are about 0.2%.     

氘双等离子体离子源的进展

一、引言低能加速器型中子发生器利用D-T反应能产生单色的14MeV快中子。发生器对离子束的要求既可以是原子离子(即必须分析),也可以是混合束(即不经分析)。现在中子发生器大多采用磁分析,虽然设备复杂些,但还是有其优点的。在原先调试的基础上,我们又进行了束分析的调试,源的结构也做了一些改进,使源的性能有了进一步提高。     

MOISTURE PROFILES IN A MODEL FOOD GEL DURING DRYING: MEASUREMENT USING MAGNETIC RESONANCE IMAGING AND EVALUATION OF THE HCKIAN MODEL

Magnetic resonance imaging (MRI) was used to obtain moisture profiles of a model food gel during drying. A cylinder of gel, 1 cm in diameter, with an initial moisture content of 76% was imaged while drying at room temperature. Moisture profiles were obtained from the imaging data by imaging calibration samples of known moisture content. Signal intensity of the images was found to be highly proportional to solids content. The moisture profiles were compared to profiles predicted by a finite difference solution of Fickian radial diffusion in a cylinder. Actual moisture profiles obtained by MRI were much flatter near the center of the cylinder, with a steeper moisture profile near the edge, compared to the typical parabolic shape of the Fickian model. The Fickian model was found to be an inaccurate predictor of the interior moisture profile of the model food gel, since effective diffusivity was found to not be solely a function of moisture content. The moisture profiles obtained provide for a method to evaluate other mass transfer models, and the methods outlined provide a technique to explore mass transfer within actual food materials during processing.     

适应社会管理创新 做好职工群众工作

加强企业和社会的双重管理意义重大。深度剖析企业出现的新问题和成因,积极寻找解决问题对策,是促进企业和谐发展、做好群众工作的有效途径。     

运输机质量特性快速计算方法探讨

飞机质量特性计算是飞机重量工程的一项十分重要同时也是十分复杂困难的工作。本文研究了飞机质量特性的计算,探讨了一种适合于运输机结构质量特性的近似快速计算方法,该方法形式简单,计算简便。算例表明,本方法提供了一种飞机设计中计算质量特性的快速而有效的工具。     

1,2,4—三嗪类化合物的研究ⅩⅧ.——1,2,4—三嗪类化合物的质谱研究

本文对合成的四种新类型21个1,2,4—三嗪类化合物的质谱进行了研究。发现各种类型的1,2,4—三嗪类化合物具有各自不同的裂解方式。     

Mathematical modelling of styrene drying by adsorption onto activated alumina

This work is focused on the analysis and modelling of styrene drying, raw material in the manufacture of synthetic rubber, by means of adsorption onto activated alumina. Equilibrium experiments, carried out under isothermal conditions at 10°C, correlated to the equation q (kg/kg)=2.659×10⁻⁴ C (mg/kg). Fixed bed column experiments were performed working with different flow rates and using different bed lengths in order to obtain experimental breakthrough curves. A mathematical model that considers the influence of both film and pore mass transfer resistances described satisfactorily well the experimental results. Finally a value of D_p=6.101×10⁻⁹ m²/s was obtained from correlation of experimental data to simulated curves and using the minimum weighted standard deviation as optimisation criterion.     

旋流塔板传质模型研究

根据旋流塔板上的气液运动规律，建立气相二维定数混合池传质模型，并用ＣＯ_２－ａｉｒ／Ｈ_２Ｏ物系的传质试验结果进行验证，结果表明，模型计算值和实验值相当吻合。     

Characterization of aquatic groundwater colloids by a laser-induced breakdown detection and ICP-MS combined with an asymmetric flow field-flow fractionation

This study investigated the characteristics of natural groundwater colloids by a laser-induced breakdown detection (LIBD) and inductively-coupled plasma mass spectrometry (ICP-MS) in a combination with an asymmetrical flow field-flow fractionation (AsymFFFF). The groundwater was sampled from a borehole in the Yuseong area of Daejeon, Korea at different geological depths from 30 to 460 m and its geochemical parameters were measured. The combination of AsymFFFF and LIBD revealed a heterogeneous size fraction with a relatively broad size distribution of the groundwater colloids. One of the size fractions of the groundwater colloids was about 20 nm up to smaller than 100 nm, and the other fractions were larger than 100 nm. The elemental composition of the groundwater colloids was also analyzed by the AsymFFFF coupled with an ICP-MS. Results from the ICP-MS coupled with the AsymFFFF provided us with information about the size-specific elemental composition. The smaller sized fractions mainly consisted of calcite colloids with strontium, whereas the larger fractions were comprised of colloids such as aluminosilicates and iron oxides. The observations of all the groundwater samples indicate a similar pattern for the colloid fractions in size and in element composition except in the concentration.     

环流反应器中肌苷发酵液的氧传递研究

根据肌苷发酵过程主要是溶氧传质控制的结论,本文研究了操作变量和装置结构变量对环流发酵反应器中氧传递的影响,定量地得到气含率,液体循环速度和结构因素对氧传递的关系。对发酵反应器中溶氧浓度分布进行了摸拟计算,依据计算的结果提出了较佳的 D_E/D 和 L_E/D 的结构。