Measurement of transient heat flux using heat gauges

This paper describes the theoretical basis, the design, and the method of calibrating heat gauges for measuring variable heat fluxes.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 29, No. 5, pp. 814–820, November, 1975.     

Measurement of rotating flux in silicon iron laminations

A method of calculating the magnitude and direction of the instantaneous flux density in a thin lamination of magnetic material is described. The technique was demonstrated by measuring the rotating flux in samples of mild steel, grain-oriented silicon iron, and at a point in the T-joint of a three-phase, three-limbed transformer core. The flux in the mild steel sample was found to rotate at a constant angular velocity and to be constant in magnitude. In the silicon iron sample, and at a point in the T-joint, the flux density varied both in angular velocity and magnitude. A large 150 Hz component of rotational flux was found to cause high localized power loss in the T-joint. The power loss was measured using the "initial rate of rise of temperature method" and was compared with the predicted rotational hysteresis loss.     

高通量超支化聚硅氧烷复合膜渗透汽化分离水中正丁醇

为得到高通量的水中脱除丁醇渗透汽化膜HPSiO-c-PDMS,采用AB₂型单体缩合法合成了超支化聚硅氧烷（HPSiO）并将其与端羟基聚二甲基硅氧烷（PDMS）交联制备渗透汽化复合膜.对超支化聚硅氧烷和HPSiO-c-PDMS膜进行了化学结构和形态表征,并系统研究了PDMS分子量大小对膜结构及其渗透汽化性能的影响.结果表明:超支化聚合物支化度（DB）达到0.73;HPSiO-c-PDMS膜具有较大的通量和分离因子,随着PDMS分子量的增加,其渗透通量减小而分离因子增加.     

Measurement of the power flux density of extraneous radiations

The requirements imposed on the frequency-selection parameters, and also on the sensitivity and screening of the measuring apparatus are established.     

Measurement of flux distribution in toroidal and multiaperture cores

Recently, magnetic devices utilizing a partial switching have been used in many fields. From a point of core design, a flux distribution must be known. It is possible to calculate them under some assumptions, but it is difficult to measure them experimentally. This paper describes a technique of determining a flux distribution in toroidal and multiaperture ferrite cores. The patterns of flux distribution are expressed by a flux of local zone. The flux level is determined by measuring a second-harmonic voltages induced in a pick up coil under an application of a small ac magnetic field (10 kHz) orthogonal to the plane of core. Small holes for sensing are drilled through the core, and the pick up coil encloses cross-sectional areas between each of the holes. It was found that a flux reversal boundary in a toroidal core travels from inner edge to outer edge when it is switched partially by a dc field, but a pulse field switching produces a complex flux distribution, and that in both cases, the flux reversal boundary is not sharp. By a similar method, the flux distribution in the transfluxor is shown for the "unblocked" and "blocked" state before and after the interrogation. The transfluxor in the unblocked state after the interrogration showed a "kidney shaped" pattern. Readout characteristics obtained from the measured flux distributions agree with those obtained by ordinary induced voltage methods. The accuracy of the readout flux is about 8.7 percent.     

Impact of biofouling on diffusive gradient in thin film measurements in water

The technique of diffusive gradient in thin film (DGT) is commonly used to assess metal contamination in natural waters. In this paper, we assess the effect of biofouling on DGT measured labile concentrations in water and investigate whether an additional nuclepore polycarbonate membrane on the surface of DGT devices can limit biofilm growth. Simultaneous field deployments of DGT equipped with and without the additional membrane in a canal receiving wastewater were compared. The effect of the biofilm was also assessed in controlled laboratory experiments, completed by the experimental determination of several metals diffusion coefficients in the hydrogel and membrane systems. The biofilms effect was problematic only from the 10th day of accumulation. Accumulation of some elements is highly biased by the presence of a thick biofilm (Zn, Ni, Cd). The polycarbonate membrane improved the quantification of Cd and Ni but adversely affects the quantification of Cr and Co. A kinetic model is proposed to explain the biofilm role on the DGT measurement. Depending on the metals of interest, it is possible to limit bias due to biofilms by using an additional polycarbonate membrane.     

Measurement of ammonia in human breath with a liquid-film conductivity sensor

Measurement of breath NH3 is of interest in clinical applications as it can be used as a measure of kidney/liver functions as well as halitosis. We have developed a liquid-film conductivity sensor to measure NH3 in human breath. A film of dilute H2SO4 is formed on the top of two metal capillary tubes placed in a concentric annular arrangement. The tube exterior has been specially treated to render it hydrophilic. As breath passes over the sensor tip, the film collects NH3 and the solution conductivity (measured by the concentric capillaries functioning as electrodes) decreases accordingly. This initial rate of conductivity decrease was determined to be the best metric (most rapid and least dependent on breath pCO2) for ammonia, relative to time to attain complete neutralization (conductivity minimum) or the final rate of conductivity increase as more ammonia dissolves after neutralization. The absorbing solution composition was optimized so that CO2 does not interfere. Both dynamic measurement using mask sampling and offline balloon sampling were performed. Ammonia readily absorbs on surfaces when significant concentrations of water vapor are present. As such, memory effects are common when analyzing human breath for ammonia. This problem was successfully eliminated. The results from this sensor agreed well with data obtained by a solution-phase fluorometric technique using a porous membrane diffusion scrubber and o-phthalaldehyde derivatization chemistry. For breath CO2 measurement, the applicability of a similar sensor that relies on a NaOH film was also demonstrated.     

Measurement of water transport from saturated pumice aggregates to hardening cement paste

In internal water curing of High Performance Concrete, it is fundamental to know how and when the water contained in the internal curing agent is released into the hydrating cement paste. In this study, X-ray absorption measurements showed that considerable transport of water from saturated pumice stone to hydrating cement paste with water/cement ratio 0.3 took place in the first days after casting and covered a distance of at least 4 mm. As a consequence, the total amount of water released by the lightweight aggregates, rather than the spatial distribution of the aggregates, is in this case the crucial factor to avoid self-desiccation shrinkage at early-age.     

脉冲电弧放电电离甲醇/氨水溶液合成结晶氮化碳薄膜

利用脉冲电弧放电在大气压下产生的高密度等离子体研究了结晶氮化碳薄膜的低温合成。直流脉冲电弧等离子体由甲醇／氨水溶液液滴通过高压电极时诱导放电产生。利用扫描电子显微镜、X射线衍射、Raman光谱分析了薄膜样品的形貌和结构。在基片温度为450℃时所制样品的X射线衍射分析表明薄膜中含有α-C3N4和β-C3N4两种结构晶体，Raman光谱给出了明显的特征峰，这些特征峰与氮化碳晶体的理论预言值符合较好。当基片温度提高到550℃时．Raman光谱分析表明，样品为炭膜。     

超滤膜渗透通量法评价水质的研究

提出了一种通过超滤膜水的渗透通量或渗透体积评价水质污染状态的新方法．从我国不同地区取来18种水质,包括井水、河水、海水、湖水,并用固定超滤膜的超滤实验装置进行了测试,水渗透体积和水通量随时间的变化可以表征水样中污染物的含量,以此描述水质的差别．由串联阻力模型推导出的修正污染指数（MFI）数学关系并结合渗透体积和水通量的实验数据拟合出18种不同水质的MFI．结果表明,水渗透体积随时间、渗透通量随时间及操作压力的变化与MFI值是一致的．并且从膜污染的理论上解释了超滤膜的实验结果．     

Generation of water waves and bores by impulsive bottom flux

The inviscid free-surface flow due to an impulsive bottom flux on constant depth is investigated analytically and numerically. The following classes of two-dimensional flow are considered: an upwelling flow which is uniform over a half-plane, a line source/sink, and a dipole aligned along the bottom. The bottom flux is turned on impulsively and may decay with time. The fully nonlinear problem is solved numerically. A small-time asymptotic expansion to third order is found for the nonlinear problem. An asymptotic large-time solution is found for the linearized problem. A steady source will generate a pair of symmetric bores, and their breaking is investigated. A steady sink generates a depression wave if it is weak, and dip instability if it is strong. Wave breaking will occur for intermediate sink strengths. A decaying source emits solitary waves.     

EDI对于去除太空用水中弱电解质--氨的研究

研究了太空站水的总循环开发中EDI膜堆电流、进水的总氨浓度、进水流量等因素对EDI去除氨的影响,并对各影响因素进行了解释．实验结果显示：在氨进水质量浓度高达208．3mg／L的情况下,出水总氨的质量浓度为0．072mg／L,EDI对氨的去除率为99．97％．