Reconstruction of electrical capacitance tomography images based on fast linearized alternating direction method of multipliers for two-phase flow system

Electrical capacitance tomography(ECT)has been applied to two-phase flow measurement in recent years.Image reconstruction algorithms play an important role in the successful applications of ECT.To solve the ill-posed and nonlinear inverse problem of ECT image reconstruction,a new ECT image reconstruction method based on fast linearized alternating direction method of multipliers(FLADMM)is proposed in this paper.On the basis of theoretical analysis of compressed sensing(CS),the data acquisition of ECT is regarded as a linear measurement process of permittivity distribution signal of pipe section.A new measurement matrix is designed and L1 regularization method is used to convert ECT inverse problem to a convex relaxation problem which contains prior knowledge.A new fast alternating direction method of multipliers which contained linearized idea is employed to minimize the objective function.Simulation data and experimental results indicate that compared with other methods,the quality and speed of reconstructed images are markedly improved.Also,the dynamic experimental results indicate that the proposed algorithm can ful fill the real-time requirement of ECT systems in the application.

DIRECT TITRATION OF VERY WEAK ACIDS(BASES)IN AQUEOUS SOLUTION WITH STRONG BASES(ACIDS)USING VISUAL END-POINT INDICATION WITHOUT INDICATOR

This paper reports a new method of titration for very weak acids and bases using the appearance of incisions on oscillopolarogram to indicate the end-point.This method has the advantages of rapidity,simplicity,no indicator needed as well as good precision.

Measurement and Correlation of Equilibrium Data for Aqueous Two-phase System Ethanol+Water+ K_2HPO_4

The isothermal solubility data of aqueous two-phase system ethanol+water+K 2HPO 4 were determined with the turbidity titration method at 303.2 K. The binodal curves were described by using the Mistry equation very well. An experimental procedure for measuring the liquid-liquid equilibrium data of the aqueous two-phase system was proposed, in which the concentrations of the coexisting phases were determined with the corresponding densities of the solution. The tie lines were satisfactorily described by using the Othmer-Tobias and Bancroft equations.

3种测定广式酱油中总糖含量的方法比较

该研究通过比较直接滴定法、苯酚硫酸法、蒽酮硫酸法3种方法测定广式酱油总糖含量的差异,并对这3种方法进行方法学验证,以期筛选出一种适合广式酱油总糖含量测定的方法。结果显示,直接滴定法、苯酚硫酸法和蒽酮硫酸法分别在0.50~8.00、0.00~0.08和0.00~0.08 mg/mL范围内线性关系良好。直接滴定法、苯酚硫酸法和蒽酮硫酸法的精密度试验的RSD值分别为1.07%、0.05%、0.05%,重现性试验的RSD值分别为0.88%、3.93%、3.24%,直接滴定法在24 h内显色稳定,苯酚硫酸法和蒽酮硫酸法在1 h内显色稳定。而在加标回收率试验中,蒽酮硫酸法的平均加标回收率较高,为168.04%,RSD值为2.97%,直接滴定法的平均加标回收率为104.67%,RSD值为2.07%,苯酚硫酸法的平均加标回收率为103.85%,但其RSD值为8.04%,蒽酮硫酸法测定酱油总糖含量的准确度低于其他两种方法。因此,直接滴定法和苯酚硫酸法的精密度、重现性、稳定性良好,理论上均具有可行性,蒽酮硫酸法不适合用于广式酱油总糖含量的测定。酱油中总糖含量是反映酱油品质的基本指标之一,筛选出适合酱油总糖含量的检测方法,对实际酱油生产监控和产品加工过程的品质控制都有重要意义,同时也为酱油总糖含量测定方法标准的制定提供一定的实验参考。

Laser Doppler Vibrometer Without Directional Ambiguity Using Rectangular Phase Grating

The two-phase detection method for directional discrimination in laser Doppler measurements is discussed.The diffraction efficiency of a sin- gle period rectangular phase grating is analysed and a kind of back-scattered laser Doppler vibrometer without directional ambiguity using the single peri- od rectangular phase grating as the beam-combiner described.The principles of this kind of vibrometer are explained in detail,and some experimental re- sults are given.In this kind of vibrometer,the rectangular phase grating, without the zero diffracted order and even orders,is used to eliminate use- less stray light and to combine the useful signal light.Differential electronics is employed to reject signal noise.Therefore,the signal-to-noise ratio of Doppler signals and the measurement accuracy of the instrument are im- proved and the range of application is expanded.

影响食用盐碘含量检验结果的因素分析

食用盐中碘含量的检验是确保食用盐质量安全的一种重要手段,探究影响食用盐碘含量检验结果的因素,为更加真实准确反映食用盐碘含量检验结果提供参考。结果显示:对食用盐样品进行研磨处理后,再通过氧化还原滴定法可测得食用盐样品中的总碘含量,以湖盐为原料生产的食用盐比井矿盐和海盐在测定结果中碘含量偏高,以此提出优化食用盐碘含量检验结果的措施建议。

含短碳链烷基硫酸盐活性物含量测定方法探讨

国标GB/T5173-2022规定直接两相滴定法测定烷基硫酸盐活性物含量的具体方法,但在实际测定过程中发现随着疏水基碳链越来越短,活性物的偏差越来越大。为了解决此题,在根据GB/T15963和GB/T20200测定阴离子表面活性剂活性物含量的基础上,通过改变移取量、溶剂种类、溶剂量等因素测定一系列不同碳链烷基硫酸盐样品,并对比生产过程中的物料平衡,从而选定适用于含短碳链烷基硫酸盐阴离子表面活性物的测定方法。结果表明:通过溶剂增量对比法,随着烷基硫酸盐疏水链越来越短,测定结果偏差逐渐趋于一致,最终确定实验方法8来测定含辛基硫酸盐的阴离子表面活性剂活性物含量。此研究为生产指导、品质控制和指标调整具有重要的实践指导意义。

Two-phase flow in anode flow field of a small direct methanol fuel cell in different gravities

An in-situ visualization of two-phase flow inside anode flow bed of a small liquid fed direct methanol fuel cells in normal and reduced gravity has been conducted in a drop tower.The anode flow bed con-sists of 11 parallel straight channels.The length,width and depth of single channel,which had rec-tangular cross section,are 48.0,2.5 and 2.0mm,respectively.The rib width was 2.0mm.The experi-mental results indicated that when the fuel cell orientation is vertical,two-phase flow pattern in anode channels can evolve from bubbly flow in normal gravity into slug flow in microgravity.The size of bub-bles in the reduced gravity is also bigger.In microgravity,the bubbles rising speed in vertical channels is obviously slower than that in normal gravity.When the fuel cell orientation is horizontal,the slug flow in the reduced gravity has almost the same characteristic with that in normal gravity.It implies that the effect of gravity on two-phase flow is small and the bubbles removal is governed by viscous drag.When the gas slugs or gas columns occupy channels,the performance of liquid fed direct methanol fuel cells is failing rapidly.It infers that in long-term microgravity,flow bed and operating condition should be optimized to avoid concentration polarization of fuel cells.

Study on two-phase countercurrent flow and transport phenomenon in PEM of a direct methanol fuel cell

Based on the requirement of water management for a direct methanol fuel cell, this paper analyzes qualitatively the mechanism of occurrence and development of a two-phase countercurrent flow with corresponding transport phenomenon in the PEM. A one-dimensional, steady state quantitative model of heat and mass transfer in internal volumetric ohmic heating porous media saturated by liquid and vapor phases is developed. The effects of capillarity, electro-osmotic drag and phase change are included. Two im-portant formulas to calculate the theoretical length of two-phase zone δ t and determine the critical criterion |?ω /γ |cr for dryout in PEM are deduced. By use of these two dimen-sionless parameters, dryout of PEM can be easily predicted. Theoretical temperature, pressure and saturation profiles within the two-phase region are obtained numerically, which can help to explore the performance of a DMFC operating in its ohmic polarization region. The simulation results can be used to determine the catalyst content of cathode catalyst layer and the corresponding optimal thickness of PEM.

脱硫石灰粉氧化钙含量检测方法

用EDTA络合滴定法测定脱硫石灰粉中氧化钙的含量。盐酸直接溶解试样,用三乙醇胺掩蔽铁、铝、锰等离子,在强碱介质中,以钙指示剂为指示剂,用EDTA标准溶液滴定氧化钙含量。

结晶陈化技术在滴定分析铅阳极板中银含量的应用

试样用硝酸(1+4)溶解,逐步降温使其结晶,静置过夜使晶体充分长大,降低铅离子在溶液中的浓度,抑制其干扰,过滤后,在强酸介质中,加入三价铁离子指示剂,用硫氰酸钾标准溶液滴定铅阳极板中的Ag含量。该方法结果稳定、准确度高,试验加标回收率在99.84%~100.03%之间,相对标准偏差小于0.33%,测定范围在2000~20000 g/t之间具有合乎要求的线性和相关度,用火试金富集-重量法对照得到的结果。

铁矿石中铁含量测定的条件探究

基于铁矿石快速直接测定的研究背景,在简要介绍铁矿石快速直接测定铁的基础上,通过实验测试的方法对铁矿石快速直接测定的设计过程进行了条件优化,确定了溶样电阻丝的功率,对硫-磷混合酸的配比以及使用体积、还原温度等条件下,快速直接滴定铁矿石中铁的结果进行了探讨,以稳步提高快速直接测定铁矿石中铁的应用水平。

香菇多糖测定的方法学研究

为选出一种比较准确、方便的香菇多糖的测定方法 ,对蒽酮—硫酸法、苯酚—硫酸法、直接滴定法三法进行了比较。实验结果表明 :蒽酮—硫酸法所测香菇多糖含量偏高 ,回收率过高 (113 6 %～ 145 1% ) ;直接滴定法灵敏度不高 ,回收率偏低 (42 8%～ 85 8% ) ;而苯酚—硫酸法不仅灵敏度高 ,回收试验也较理想 (92 5 %～ 110 2 % )。因而 。

食品多糖含量不同测定方法的研究

[目的 ] 食品多糖因其功能显著而受到广泛的重视 ,但不同的食品 ,其多糖含量差异很大。因此 ,找出可行的食品多糖的测定方法尤为重要。 [方法 ] 对食品中多糖采用滴定法、苯酚硫酸法、蒽酮法三种不同测定方法进行研究比较。 [结果 ] 发现目前常用的蒽酮法、苯酚硫酸法、滴定法中 ,以苯酚硫酸法较为可靠 ,可以作为测定食品多糖的首选方法。对于含蛋白质较多的样品 ,测定多糖时应先用蛋白沉淀剂沉淀蛋白 ,以减少蛋白质对多糖含量测定的影响。对羊栖菜、香菇、灵芝和某厂生产的营养酒中的多糖进行测定 ,发现香菇中多糖含量最高。 [结论 ] 多糖的测定方法以蒽酮法和苯酚硫酸法比较好 。

3种测定乳制品中乳糖含量方法的比较

为确定一种快速、简易、灵敏的测定乳糖的方法,比较了直接滴定法、蒽酮法和碘量法3种方法测定乳制品中乳糖含量的差异。结果表明:平行试验直接滴定法精度最低,但其乳糖回收率的最大相对误差最小;蒽酮法精度高,但其乳糖回收率的最大相对误差最大,而且蒽酮试剂腐蚀性强,操作不安全;碘量法的精度与乳糖回收率的最大相对误差均介于直接滴定与蒽酮比色法之间,综合而言,碘量法的重复操作性强,结果准确,测定乳制品中乳糖含量可优选碘量法。

高性能水泥基材料结合外渗氯离子能力的测试方法对比

高性能混凝土掺各种微细掺合料后,由于这些掺合料的自身特性,酸溶时发现部分试样有难溶絮状物质生成,这种物质对氯离子有一定的吸附性,所以增加了测试结合外渗氯离子的难度。本文进行了大量的试验证实:佛尔哈德法可以直接进行滴定分析,能将吸附的氯离子释放出来,这种方法用铁铵矾作指示剂,不仅适合于酸性介质,滴定终点直观,而且测试的精度对实验室研究,高于莫尔法和离子选择电极法。

桦褐孔菌多糖测定方法的比较

为选出一种比较准确、方便的测定真菌多糖的方法,以桦褐孔菌菌丝体发酵液提取的粗多糖为原料,对苯酚-硫酸法、蒽酮-比色法、斐林滴定法3种方法进行比较。3种方法比较而言,苯酚-硫酸法与蒽酮-比色法测得的糖含量相差甚微,分别为61.07%、62.25%。苯酚-硫酸法显色不稳定,蒽酮-比色法比较容易操作,测定的多糖含量和回收率均最高,回收率为125%;斐林滴定法回收率较低45%,测得的多糖含量偏低为33.12%,最终确定蒽酮-比色法为最佳测定方法。

葡萄酒中还原糖含量测定方法的研究

比较测定葡萄酒中还原糖含量的两种方法———直接滴定法和改进后的碘量法 ,研究结果表明 ,改进后的碘量法比直接滴定法的终点易于分辨 ,测定数据重复性强、精密度和准确度高 ,易于操作。

直接电位滴定法测定半夏提取物中总游离有机酸的含量

目的 建立半夏中总游离有机酸含量的测定方法。方法 采用直接电位滴定法进行含量测定。结果 半夏总酸提取物中总游离有机酸的含量为38.41%(以琥珀酸计),RSD=0.49%(n=6),琥珀酸加样回收率为98.79%～101.31%。结论 该方法精密度好,准确度高,可以作为半夏中总游离有机酸的质量控制方法之一。

酒类行业生产中还原糖测定水平鉴定方法研究

配制并筛选出了一种能鉴定还原糖测定水平的标准液,该标准液为1000mL水溶液中加入1.00g葡萄糖、2.00mL的盐酸和0.02g的双倍焦糖色素。通过对某酒厂化验人员的验证试验说明了该标准液用于鉴定还原糖测定水平的可行性。