INSTRUCTIONS FOR PREPARATION OF MANUSCRIPTS FOR DIRECT REPRODUCTION

ABSTRACT

The bulk density of garlic slices at different moisture levels (ranging from approximately 3 to 65% MC wet basis) was determined by weighing the contents of a container of known volume. The porosity was calculated using its relationship with bulk and apparent densities. An analysis of variance (ANOVA) revealed that bulk density and porosity were affected significantly by moisture and slice thickness as well as the interaction of these variables. Bulk density varied in a positive linear fashion with moisture and thickness while a negative linear correlation was found for the calculated bulk porosity. The linear model met me adequacy criterion for characterising the behaviour of garlic. Using a laboratory unit, the vertical resistance to airflow through the product and die effect of moisture and slice thickness were investigated for an airflow rates of 0.09 to 1.2 m³/s-m². A higher resistance to airflow was noted for the wet product with the experimental data fitting to Shedd's model when the airflow range was divided into two sub-flow rates and to a modified Ergun's equation for the full range.     

Bulk Density, Porosity and Resistance to Airflow of Garlic Slices

The bulk density of garlic slices at different moisture levels (ranging from approximately 3 to 65% MC wet basis) was determined by weighing the contents of a container of known volume. The porosity was calculated using its relationship with bulk and apparent densities. An analysis of variance (ANOVA) revealed that bulk density and porosity were affected significantly by moisture and slice thickness as well as the interaction of these variables. Bulk density varied in a positive linear fashion with moisture and thickness while a negative linear correlation was found for the calculated bulk porosity. The linear model met the adequacy criterion for characterising the behaviour of garlic. Using a laboratory unit, the vertical resistance to airflow through the product and the effect of misture and slice thickness were investigated for an airflow rates of 0.09 to 1.2 m₃/s-m₂. A higher resistance to airflow was noted for the wet product with the experimental data fitting to Shedd's model when the aifflow range was divided into two sub-flow rates and to a modified Ergun's equation for the full range.     

Effective Medium Theory of the Porosity Dependence of Bulk Moduli

Effective medium theory is used to obtain a closed- form expression for the porosity dependence of the bulk moduli of ceramics. The theory is illustrated with an application to data for high-purity alumina that spans a volume fraction of porosity ranging from 0.5% to 90%.     

A New Adsorption Based Correlation for Estimation of Membrane Bulk Porosity

In this work, a new simple correlation has been derived for the prediction of the bulk porosity decline during nanofiltration of a salty (ionic) solution using the PVD membrane. This model has been developed on the basis of the adsorption of the cations available in the feed onto the membrane. Therefore, three adsorption isotherms were tested and fitted to the equilibrium adsorption data, and the Freundlich isotherm was subsequently realized as the best choice. The porosity model included two adjustable parameters which can be determined theoretically and experimentally. Adsorption isotherms were combined for the determination of the first parameter and a novel method called “Flux test” was developed for the other parameter estimation. A reasonable agreement was observed between experimental- and model-predicted porosity. The model's ability of estimation indicates a little decrease at higher pressures due to approaching an unfavorable equilibrium adsorption condition and deviation from the isotherm's parameters from the actual equilibrium amounts to this situation.     

Dense Shaped Refractory Products —— Determination of Bulk Density, Apparent Porosity and True Porosity

1 Scope This standard specifies the definition, principle, apparatus and materials, proc edure, expression of results and test report of determination of bulk density, a pparent porosity and true porosity of dense shaped refractory products.1 Scope This s…     

规整填料层压降的计算及与散装填料的比较

根据文献[6]导出的规整填料层压降关联式,由实验数据计算出9种规整填料本文关联式的压降常数,用空气-水物系和非水物系的实验数据进行了验证,并与Billet关联式计算值和实验值进行了比较;对规整填料层与散装填料的泛点和压降进行了比较。结果表明:该关联式与实验数据吻合较好,压降计算误差在±15％;规整填料力学性能优于散装填料。     

一种粉料的输送特性研究

利用自主研究设计的工业规模级气力输送装置,分析研究了一种粉料稀相气力输送的规律.通过在两条不同长度输送线上的大量系统实验,得出输送量、输送压力、气量、固气比、表观气速等输送参数间的相互关系,展现了该粉料输送的宏观规律.同时对气力输送设计计算最重要的参数“管道压降”进行分析讨论,整理拟合出该粉料不同输送量下的压降模型,并且其计算值与实际值吻合较好,对工程应用具有一定指导意义.     

散装填料层泛点和压降的新关联式

导出了散装填料层泛点和压降的新关联式,将该关联式与通用关联图进行了比较,计算结果表明,新关联式对各种填料的压降平均计算误差在10％以下,泛点计算误差在7％以下,计算准确性优于通用关联图;用通用关联图计算压降有时误差较大。     

添加剂对硫脲晶习及堆积密度的影响

研究了聚乙二醇、氯代十六烷基吡啶、十二烷基苯磺酸钠三种添加剂对硫脲晶习及堆积密度的影响,研究发现,加入聚乙二醇后晶体呈菱形的薄片状,加入氯代十六烷基吡啶后晶体呈平行四边形的薄片状,加入十二烷基苯磺酸钠能得到厚实的晶体。十二烷基苯磺酸钠的加入量存在一个最佳值,当加入5mg/L的十二烷基苯磺酸钠时,得到长径比约为1：1的长方体形硫脲晶体,20～30目硫脲晶体的堆积密度由0．59g/mL提高到0．74g/mL。     

Effects of Matrix Porosity on the Mechanical Properties of a Porous-Matrix, All-Oxide Ceramic Composite

The effects of matrix porosity on the mechanical properties of an all-oxide ceramic composite are investigated. The porosity is varied through impregnation and pyrolysis of a ceramic precursor solution. Mechanical tests are performed to assess the role of the matrix in both matrix-dominated and fiber-dominated loading configurations. The results demonstrate a loss in damage tolerance and tensile strength along the fiber direction as the porosity is reduced. Concomitantly, some improvements in interlaminar strength are obtained. The latter improvements are found to be difficult to quantify over the entire porosity range using the standard short beam shear method, a consequence of the increased propensity for tensile fracture as the porosity is reduced. Measurements of interlaminar shear strength based on the double-notched shear specimen are broadly consistent with the limited values obtained by the short beam shear method, although the former exhibit large variability. In addition, effects of precursor segregation during drying on through-thickness gradients in matrix properties and their role in composite performance are identified and discussed. An analysis based on the mechanics of crack deflection and penetration at an interphase boundary is presented and used to draw insights regarding the role of matrix properties in enabling damage tolerance in porous-matrix composites. Deficiencies in the understanding of the mechanisms that enable damage tolerance in this class of composites are discussed.     

Effect of Porosity on the Electrical Properties of Polycrystalline Sodium Niobate: I, Electrical Conductivity

The electrical behavior of NaNbO₃ ceramic samples with different relative densities was investigated by ac impedance spectroscopy in a range of 13 MHz to 10⁻³ Hz between 400° and 800°C in dry air. Measurements were performed during heating and cooling cycles. The Nyquist impedance diagrams of dense sodium niobate exhibit only one semicircle representing the grain contribution with depression angles as small as 1°, indicating a high homogeneity of the specific electrical properties. In the case of porous samples, the data reveal an additional low-frequency semicircle related to microstructure. For all studied samples, the Arrhenius conductivity plots show a change in the activation energy around 640°C, attributed to the tetragonal-cubic phase transition. The electrical conductivity of porous samples appears to be higher than that of dense ones.     

Porosity,Bulk Density,and Volume Reduction During Drying: Review of Measurement Methods and Coefficient Determinations

Several experimental methods for measuring porosity, bulk density, and volume reduction during drying of foodstuffs are available. These methods include, among others, geometric dimension, volume displacement, mercury porosimeter, micro-CT, and NMR. However, data on their accuracy, sensitivity, and appropriateness are scarce. This article reviews these experimental methods, areas of applications, and limits. In addition, the concept of porosity, bulk density, and volume reduction and their evolution as a function of moisture content during drying are presented. In this study, values of initial porosity (?₀) and density ratio (β) of some food products are summarized. It has been found that ?₀ is highly dependent on the type of food products, while β ranges from 1.1 to 1.6. The possibility of calculating solid density based on food compositions has also been validated. The inter-predictions between porosity, bulk density, and volume density have been made mathematically evident.     

Effect of Porosity on the Electrical Properties of Polycrystalline Sodium Niobate: II, Dielectric Behavior

The dielectric behavior of dense and porous NaNbO₃ ceramic samples, synthesized by a suitable chemical route, was investigated by impedance spectroscopy between room temperature and 800°C in dry air. The dielectric behavior and thermal stability of the samples were evaluated as a function of several thermal cycles. The dielectric constant was calculated from the relaxation frequency, and from an alternative approach based on the variation of the opposite of the imaginary part of impedance as a function of reciprocal angular frequency. The values obtained using both relations were in a good agreement. After the porosity was corrected, the porous and dense samples presented the same dielectric constant. All samples evaluated displayed a broad dielectric anomaly between 300°–400°C. Neither the orthorhombic-tetragonal- nor the tetragonal-cubic-phase transitions were detected by dielectric measurements. The Curie-Weiss law was found to be valid above the transition temperature, whereas the corresponding phase transition presented a diffuse nature. The origin of the related thermal hysteresis is discussed herein.     

合成氨生产中固定层反应器阻力降分析及降阻措施

阻力降是固定层反应器的重要参数,低阻力降的反应器是工程设计的努力方向,对节能降耗具有重要的意义.通过分析阻力降影响因素,结合变换反应器、甲醇合成反应器、氨合成反应器设计,提出可行的降低床层阻力降的措施,并在工业生产中得到很好的应用.     

Effect of Pretreatments on Drying and Rehydration Kinetics and Color of Sweet Potato Slices

The effect of air temperature and pretreatments (KMS: citric acid) on drying kinetics of sweet potato slices was investigated. Drying experiments were performed in a tray dryer. In falling rate period, moisture transfer from sweet potato slices was described by applying the unsteady-state Fickian diffusion model, and the rate constant (k) were calculated. The effect of temperature on k could be interpreted according to Arrhenius law. Drying rate and therefore k values were found to be affected by pretreatments. Rehydration rates of dried sweet potato slices at 25, 40, 80°C were also determined and found to be independent of drying conditions and rehydration temperature. The ΔE value was found to be the highest for slices treated at 50°C with 0.5:1.0% KMS and citric acid.     

铜基催化剂孔隙率对气体有效扩散系数的影响

研究了18种具有不同孔结构参数的粒状铜基甲醇合成催化剂孔隙率对有效扩散系数的影响。结果发现,催化剂微孔孔隙率增大,曲节因子亦增大,扩散阻力增加。将孔隙率与催化剂曲节因子关联,得到了半经验方程,用它可估算催化剂的曲节因子。     

Interfacial and Bulk Contributions to Peeling Energy

Thin polyurethane films, having low adhesion to dried protein, were developed as candidate materials for non-adhesive surgical dressings. In order to model wound-adhesion, gelatine was cast from solution on to the film and allowed to dry. The film was peeled from the gelatine at 180° peel angle, and the peel force measured as a function of the temperature of test. The dynamic mechanical properties of the films were measured over the range -90°C to 110°C and values of tan δ were determined at the temperatures employed for peeling. Thus, a correlation was obtained between peeling energy and tan δ for each of eight films.

The generalised theory of fracture mechanics states that the adhesive failure energy is given by the product of an interfacial energy term and a “loss function” involving the hysteresis ratio of the material. If the strains are small the hysteresis ratio is proportional to tan δ. The experimental results show excellent agreement with the theory, but the interfacial term turns out to be much greater than the true interfacial energy (or thermo-dynamic work of adhesion). The reason for this result is discussed.     

八甲基环四硅氧烷/氨基取代有机硅单体的本体阴离子共聚动力学

通过实验分析了八甲基环四硅氧烷(D4)／N—β—氨乙基-γ-氨丙基甲基二甲氧基硅烷(APAEDMS)的本体共聚机理,并结合普适的阴离子聚合机制建立了D4／APAEDMS本体共聚速率模型。通过因素(温度、催化剂浓度及原料单体配比)实验考核并完善了所建立的速率模型。研究表明,D4／APAEDMS的本体共聚具有阴离子聚合特点,也含有部分逐步聚合行为,在APAEDMS/D4质量比小的情况下,可以用普适的阴离子聚合方程进行模型化。     

Hygrothermal Properties of Adhesively Bonded Joints and Their Correlation with Bulk Adhesive Properties

The combined effects of heat (50[ddot]C) and humidity (95% R.H.) on the lap shear and T-peel strengths of 120[ddot]C, 150[ddot]C and 215[ddot]C service epoxy film adhesives have been characterized. Experimental results have indicated that effects of hygrothermal conditioning on lap shear and peel properties vary with exposure time and final testing temperatures and type of adhesive tested. In the cases where cohesive failure was observed in the shear and peel specimens, a correlation could be established between the bulk properties of the adhesives (tensile strength and elongation) and their adhesively bonded joint properties (shear and peel). When testing was carried out at room temperature, a general correlation between the tensile elongation and T-peel or shear could be obtained. At below freezing temperatures, lap shear strength seemed to be correlated with bulk tensile strength while peel correlated with bulk tensile elongation. At elevated temperatures, the relative contributions of bulk strength and elongation were the decisive factors as far as shear and peel strengths are concerned.