Liquid bubble manometer for low differential heads

The development of a highly sensitive liquid bubble manometer which can measure low differential heads to an accuracy of 0.01 mm of water is reported in this paper. The liquid bubble consists of two miscible liquids, benzaldehyde and normal hexane (each of which is immiscible in water) in such a proportion that the bubble density is within ±2 % of the density of water. The movement of the liquid bubble, which occupies the full cross-sectional area of the glass tube containing water in the manometer, is indicative of the applied differential head to a magnified scale. The manometer is found to give excellent results in open channel flow and is recommended for use for differential heads up to 2 cm of water. The manometer is economical, simple in fabrication and with simple modifications the sensitivity of the manometer can be increased to more than 0.01 mm of water.     

Equipment for determining the frequency characteristics of differential manometer flowmeters

Conclusions The above equipment and measurement technique make it possible to obtain dynamic characteristics of different recording differential and ordinary manometers, as well as of pressure transducers with a pneumatic output signal. For the latter purpose it is only necessary to use a second strain gauge, as described above, for recording the output signal and utilize the second channel of the TU-4M amplifier.     

Determination of H2O and CO2 concentrations in fluid inclusions in minerals using laser decrepitation and capacitance manometer analysis

Water and carbon dioxide concentrations within individual and selected groups of fluid inclusions in quartz were analyzed by using laser decrepitation and quantitative capacitance manometer determination. The useful limit of detection (calculated as ten times the typical background level) is about 5 x 10(-10) mol of H2O and 5 x 10(-11) mol of CO2; this H2O content translates into an aqueous fluid inclusion approximately 25 micrometers in diameter. CO2/H2O determinations for 38 samples (100 separate measurements) have a range of H2O amounts of 5.119 x 10(-9) to 1.261 x 10(-7) mol; CO2 amounts of 7.216 x 10(-10) to 1.488 x 10(-8) mol, and CO2/H2O mole ratios of 0.011 to 1.241. Replicate mole ratio determinations of CO2/H2O for three identical (?) clusters of inclusions in quartz have average mole ratios of 0.0305 +/- 0.0041 1 sigma. Our method offers much promise for analysis of individual fluid inclusions, is sensitive, is selective when the laser energy is not so great as to melt the mineral (laser pits approximately 50 micrometers in diameter), and permits rapid analysis (approximately 1 h per sample analysis).     

Control volume capacitance method for solidification modelling

The apparent and effective heat capacitance methods are popular finite element formulations used for solidification problems where conduction predominates over other heat transfer mechanisms. These methods involve the specification of element or nodal capacitances to accommodate for the release of latent heat. Unfortunately, they suffer from a major drawback in that energy is not correctly transported through elements so providing a source of inaccuracy. In this paper a capacitance method that considers the elements as control volumes is introduced. Elemental capacitances are prescribed so as to ensure that the Unsteady Flow Energy Equation (USFEE) for each element is satisfied. The new method allows for the transport of mass arising from volumetric shrinkage and ensures that energy is correctly transported. A comparison is made between the method and the well‐known temporal and spatial approximations of apparent heat capacitance, and effective capacitance. It is shown that these approaches can be highly inaccurate when energy transport is used as a criteria for judging them. Copyright © 1999 John Wiley & Sons, Ltd.     

Circulating blood volume determination using electronic spin resonance spectroscopy

There have been numerous methods proposed to measure the circulating blood volume (CBV). Nevertheless, none of them have been massively and routinely accepted in clinical diagnosis. This study describes a simple and rapid method, on a rabbit model, using the dilution of autologous red cells labeled with a nitroxide radical (Iodoacetamide-TEMPO), which can be detected by electronic spin resonance (ESR) spectroscopy. Blood samples were withdrawn and re-injected using the ears' marginal veins. The average CBV measured by the new method/body weight (CBV(IAT)/BW) was 59 +/- 7 mL/kg (n = 33). Simultaneously, blood volume determinations using the nitroxide radical and (51)Cr (CBV(Cr)) were performed. In the plot of the difference between the methods (CBV(IAT) - CBV(Cr)) against the average (CBV(IAT) + CBV(Cr))/2, the mean of the bias was -1.1 +/- 6.9 mL and the limits of agreement (mean difference +/-2 SD) were -14.9 and 12.7 mL. Lin's concordance correlation coefficient p(c) = 0.988. Thus, both methods are in close agreement. The development of a new method that allows a correct estimation of the CBV without using radioactivity, avoiding blood manipulation, and decreasing the possibility of blood contamination with similar accuracy and precision of that of the "gold standard method" is an innovative proposal.     

新型电容式靶式流量计的设计

介绍了基于差动电容结构的新型靶式流量计的基本结构、工作原理,设计了以MSP430f147为主控制器的二次仪表,通过滤波、线性修正、密度补偿等数字处理,实现对瞬时流量、累积流量等的测量与实时显示,并提供多种通讯输出方式.试验结果表明,新型电容式靶式流量计灵敏度好、量程比高、适应性强,能实现高精度、高稳定性的流量测量.     

Fast computation of static capacitance for periodic SAW transducers

An efficient algorithm to compute the static capacitance of periodic SAW (surface acoustic wave) interdigital transducers is proposed. The method is based on a new formulation of the well-known relationship giving the capacitance as a linear combination of the charges induced on an infinite transducer for one-electrode excitation. Besides computational efficiency, an interesting physical interpretation of static capacitance results. The algorithm itself is also tailored to split-finger transducers.     

Lifetime determination in delayed-coincidence experiments using the differential decay-curve approach

A new method for the analysis of delayed-coincidence lifetime experiments is proposed following the approach of the Differential decay-curve method. Examples of application of the procedure using simulated and experimental data reveal its reliability for lifetimes in the nanosecond and sub-nanosecond range. The procedure is expected to improve the treatment of systematic errors and scarce data. Possible further expansions and practical aspects of the procedure are also discussed.     

Evaluating errors in calculations of the discharge coefficient and discharge due to indirect measurement for a differential manometer

A method is presented for calculating the discharge and discharge-coefficient errors of a differential manometer due to indirect measurement. The effectiveness of the method for practical calculations is demonstrated through the use of a specific example.Translated from Izmeritel'naya Tekhnika, No. 1, pp. 39–42, January, 1995.