The impedance of the alkaline zinc-manganese dioxide cell. II. An interpretation of the data

The impedance of small alkaline zinc-manganese dioxide cells has been interpreted in terms of a controlling charge-transfer and diffusion process at the zinc electrode throughout the early stages of discharge. After about 20% of the available charge has been removed, it becomes necessary to include the manganese dioxide electrode circuit components. This network has the circuit elements for charge transfer and a proceeding chemical reaction. The Warburg component for the manganese dioxide electrode need not be considered since the effective area considerably exceeds that of the zinc. The relative areas are confirmed by the magnitudes of the circuit element components. The decomposition of the impedance data has been successfully accomplished as far as 80% discharge; after this point cells show considerable differences from cell to cell, especially in the low-frequency range, which makes a confident interpretation difficult. It is considered that this is due to the loss of the physical definition of the system.Nomenclature C _m,C _z double-layer capacitances of MnO₂ and Zn electrodes, respectively - C _X,R _X parallel branch accounting for current density varying with fractional electrode coverage - R resistance of electrolyte - V open-circuit voltage of cell - Z, Z, Z impedance of cell,resistive component ofZ and reactive component ofZ, respectively - _m, _z transfer resistance of MnO₂ and Zn electrodes, respectively - , _R, _C in Warburg equation:Z _W = ^–1/2(1–i) orZ _W = _R^–1/2– i_Cco^–1/2     

Simulation and interpretation of catalytic combustion experimental data

The catalytic combustion of CH₄/air in monoliths has been simulated through a commercial numerical fluid dynamic code. The program has been suitably modified in order to describe the heterogeneous reaction at the channel walls. Different flow arrangements have been studied in an attempt to closely match an experimental investigation reported in the literature. Single step overall rate equation has been used and identification of suitable kinetic constants performed through the use of optimization techniques. A framework for kinetic investigation accounting for complex flow structure and interaction with the chemistry is suggested. The relevant and sometimes overwhelming role of transport phenomena is discussed.     

两期膜槽压高的原因比较

宝硕集团化工分公司二、三期离子膜电压高的原因不同,分析影响槽压的膜结构、电 流密度、烧碱浓度、盐水质量、槽温、接触压降,三期膜压高的原因是阴阳极活性衰减所致。     

Note on the interpretation of powder shear test data

Powder shear testing has been used to assess flowability of powders for at least 48 years [A.W. Jenike, Storage and Flow of Solids, Bull., Eng. Exp. Station, Univ. Utah, vol. 123, 1964]. A fundamental part of the data interpretation involves construction of Mohr’s circles such that they are tangent to the experimental locus; a set of powder shear strengths, τ_m, measured at variable applied compressive normal stresses, σ_N. Despite the customary application of this tangency criterion, we have found justifications for it to be scant.In this work, we revisit the Mohr’s circle construction and find that proper construction would require measurement of reactionary lateral powder stresses, σ_r. We further provide reasoning to support placement of the experimental locus passing through the apex (top) of Mohr’s circles for isotropic or orthotropic powders and not tangentially to them. This placement is not unexpectedly in agreement with the results of a recent numerical simulation [C. Thornton, L. Zhang, Numerical simulations of the direct shear test, Chem. Eng. Technol. 26 (2) (2003) 153-156], and reveals errors in subsequently calculated constants on the order of 20%.     

On the interpretation of orifice extrusion data for viscoplastic materials

An analytical model of orifice extrusion has been developed that allows the material parameters to be derived from experimental data for materials such as pastes that may be described as viscoplastic. The geometry is based on a cylindrical square-ended barrel with variable diameter orifices. A rigid-viscoplastic constitutive relationship was employed that incorporated incompressibility and associated Herschel-Bulkley post-yield flow; the total strains were considered to be sufficiently large that elastic deformations could be ignored. The model provides a closed-form expression that relates the extrusion pressure to the material parameters. In the limit when the flow consistency is set to zero, the expression reduces to the ideal work approximation used to describe the extrusion of rigid-plastic solids. When the yield stress is set to zero, the result reduces to the solution derived by Gibson (Rheological Measurement, Elsevier, Barking, 1988, pp. 49-92) for the extrusion of power-law fluids. The model is used to analyse experimental data for a model paste and is compared to the widely applied empirical correlation of Benbow and Bridgwater (Paste Flow and Extrusion, Clarendon Press, Oxford, 1993).     

Comments on the interpretation of thermodynamic data on swollen hydrogels

Summary As a reply to the paper of Bowstra et al. (1) the authors summarize their earlier conclusions (2,3,4) concerning the interpretation of data on sorption equilibrium, heats of mixing and heat capacities of water-swollen gels. Two unavoidable premises of correct interpretation are emphasized: (1) accounting for the physical states of the polymer before and after mixing with water, (2) correct choice of the thermodynamic criterion for the stability of water structure and of its interaction with the polymer.     

A thermodynamic interpretation of differential capacity data at the metal-electrolyte interface

A new approach to the double layer problem is proposed, in which the interface is treated as a single entity, and such concepts as the compact layer, the outer Helmholtz plane and contact adsorption are unnecessary. The treatment depends specifically on known differences between anions and cations in aqueous solution.     

Theoretical interpretation of gas oil conversion data on an x-sieve catalyst

A four parameter model based on the catalyst aging theory of Wojciechowski⁽⁵⁾ is applied to experimental conversion data in gas oil cracking. The data extends over a range of cat/oil ratios from 0.094 to 3.0, and run times from 1.25 to 40 minutes. Within this range of conditions the model is applied to data with and without thermal conversion and excellent correlation between experimental results and calculated values is obtained. The technique for fitting data to the model is described in some detail.     

两种井间示踪剂定量解释方法应用对比研究

目前常用的半解析示踪剂定量解释方法存在前期准备时间长、解释效率低等问题,难以满足油田要求,需要优选其他方法作为该方法在示踪剂监测过程中的阶段性补充.基于此,以渤海某油田活化水驱井组B1为例,对该井组实施了井间示踪剂监测,并分别利用半解析法及飞行时间法对监测结果进行了定量解释,获取了水窜通道渗透率、波及体积等参数.结果 ...     

Comparison of visual and automated colorimeters—An international collaborative study

Color as a fundamental quality of edible oils has been determined primarily by visual comparison methods for many decades. The automatic colorimeters introduced recently made it possible to replace the manually operated visual color instrument, which requires experience to master and is often subject to operator variabilities. A previous study with an automatic colorimeter, Colourscan, to measure the colors of refined and refined bleached cottonseed oils showed good agreement (r ²=0.99) with visual color measurements by means of the Lovibond-AOCS Color Scale. The current work is to establish a broad-scale correlation between the automated colorimeter and visual color measurements. In this international effort, factory-processed refined and refined, bleached, deodorized (RBD) canola, corn, cottonseed, peanut, sunflower and soybean oils, as well as refined palm olein, RBD palm oil, and washed, dried, filtered and deodorized tallow were used. A total of 14 laboratories from the United States and Canada, and 16 laboratories from 12 countries outside of North America, participated in this collaborative study. The results of this study, with statistical analyses, are reported.     

两种非侵入性评估红细胞成分血血容量方法的建立及应用

目的建立两种非侵入性评估红细胞成分血血容量的方法,为准确评估红细胞成分血血容量提供参考。方法检测130袋红细胞成分血的净重量及容量,计算平均血液密度,对血净重量及容量进行相关性及线性回归分析,建立回归方程;利用血液平均密度与血净重量,建立血容量计算方程。利用上述两种方程,对100袋红细胞成分血进行检测与分析,由血净重量计算出血容量作为预期值,以实际检测出的血容量作为观察值,经t检验,分析其观察值与预期值有无显著差异,以证实该方法的可靠性。结果 130袋红细胞成分血的净重量与容量呈正相关(r=0.998,P<0.01),线性回归方程为y=0.942 3 x-2.394 1(r2=0.996,d.f.=128,F=29 819.8,P<0.01);130例袋红细胞成分血的平均密度为1.072 8,血容量计算方程为y=0.932 2 x;100袋红细胞成分血血容量的预期值与观察值比较,差异无统计学意义(P>0.05)。结论已成功建立了评估红细胞成分血血容量的两种方法,该方法操作简便、安全,结果可靠,可在输血实践中推广应用。     

溶解乙炔生产中两种净化工艺的比较

电石法生产的乙炔气中常含有H2S、PH3等杂质,产品达不到GB6819-1996《溶解乙炔》的要求,因此,用电石法生产的产品必须采用净化工艺除杂质。净化方法有干法和湿法两种,由于干法净化使用固体净化剂,净化后净化剂大都带有毒性物质,直接排放会造成环境污染,回收利用又不经济,这种方法已被禁止采用。现在推行湿法净化,使用液体净化剂,最常用的是NaClO和浓H2SO4,利用这两种物质具有氧化性的特点,将乙炔气中的气相:H2S,PH3等杂质氧化生成可溶性物质而转入液相,使乙炔气达到净化的目的。不同的净化剂采用不同的工艺流程,下面从净化工艺和生产过程的经济价值加以比较。     

矩阵换算分光光度法中两种计算方法的比较

研究了在pH为10．5的硼砂—氢氧化钾缓冲溶液和乙醇的增敏作用条件下，偶氮氯膦I与钙镁的吸收特性，建立了多波长吸光光度法同时测定钙镁的方法。采用两种矩阵算法对实验数据进行处理，并对结果进行比较和分析。钙镁质量浓度在0—1mg／L范围内用方法2能得到准确结果。     

Characterizing the performance of two optical particle counters (Grimm OPC1.108 and OPC1.109) under urban aerosol conditions

The performance of Grimm optical particle counters (OPC, models 1.108 and 1.109) was characterized under urban aerosol conditions. Number concentrations were well correlated. The different lower cut-off diameters (0.25 and 0.3 μm) give an average difference of 23.5%. Both detect less than 10% of the total particle concentration (0.01–1 μm; Differential Mobility Analyzer), but in the respective size ranges, differences are <10%. OPC number size distributions were converted to mass concentrations using instrument-specific factors given by the manufacturer. Mass concentrations for OPC1.108 were 60% higher than for OPC1.109 and (in case of OPC1.109) much lower than those measured with an impactor in the relevant size range or a TSP filter. Using the C-factor correction suggested by the manufacturer, OPC1.109 underestimated mass concentrations by 21% (impactor) and by about 36% (TSP filter), which is in the range of comparability of co-located different mass concentration methods (Hitzenberger, Berner, Maenhaut, Cafmeyer, Schwarz, &; Mueller et al., 2004).