Canadian Field Soils II. Modeling of Quartz Occurrence

The measured mineral composition data (XRD/XRF) of 40 Canadian soils were modeled for the presence of quartz as a function of soil texture. Preliminary modeling revealed a lack of strict correlation between quartz content and mass fraction of sand. For that reason, the occurrence of quartz content was modeled as dependent on a combined fraction of sand and silt, which produced an improved correlation for all tested soils. Then, all soils were modeled separately for five assigned provinces/regions of Canada and strong correlations of quartz versus combined sand and silt fractions were obtained. Estimates of quartz content and an average thermal conductivity of other minerals were also obtained by the reverse analysis of the weighted geometric mean model applied to the experimental thermal conductivity data of saturated soils. In general, quartz estimates followed XRD/XRF data sufficiently well. The thermal conductivity of the remaining soil minerals was about 2.13 W · m^?1 · K^?1 on average and did not depend on the soil texture.     

Canadian Field Soils IV: Modeling Thermal Conductivity at Dryness and Saturation

The thermal conductivity data of 40 Canadian soils at dryness \((\lambda _{\mathrm{dry}})\) and at full saturation \((\lambda _{\mathrm{sat}})\) were used to verify 13 predictive models, i.e., four mechanistic, four semi-empirical and five empirical equations. The performance of each model, for \(\lambda _{\mathrm{dry}}\) and \(\lambda _{\mathrm{sat}}\), was evaluated using a standard deviation (SD) formula. Among the mechanistic models applied to dry soils, the closest \(\lambda _{\mathrm{dry}}\) estimates were obtained by MaxRTCM \((\textit{SD} = \pm ~0.018\,\hbox { Wm}^{-1}\cdot \hbox {K}^{-1})\), followed by de Vries and a series-parallel model (\(\hbox {S-}{\vert }{\vert }\)). Among the semi-empirical equations (deVries-ave, Advanced Geometric Mean Model (A-GMM), Chaudhary and Bhandari (C–B) and Chen’s equation), the closest \(\lambda _{\mathrm{dry}}\) estimates were obtained by the C–B model \((\pm ~0.022\,\hbox { Wm}^{-1}\cdot \hbox {K}^{-1})\). Among the empirical equations, the top \(\lambda _{\mathrm{dry}}\) estimates were given by CDry-40 \((\pm ~0.021\,\hbox { Wm}^{-1}\cdot \hbox {K}^{-1}\) and \(\pm ~0.018\,\hbox { Wm}^{-1}\cdot \hbox {K}^{-1}\) for18-coarse and 22-fine soils, respectively). In addition, \(\lambda _{\mathrm{dry}}\) and \(\lambda _{\mathrm{sat}}\) models were applied to the \(\lambda _{\mathrm{sat}}\) database of 21 other soils. From all the models tested, only the maxRTCM and the CDry-40 models provided the closest \(\lambda _{\mathrm{dry}}\) estimates for the 40 Canadian soils as well as the 21 soils. The best \(\lambda _{\mathrm{sat}}\) estimates for the 40-Canadian soils and the 21 soils were given by the A-GMM and the \(\hbox {S-}{\vert }{\vert }\) model.     

Basic Problems in Thermal-Conductivity Measurements of Soils

The thermal conductivity of pozzolanic soil (a fine sandy, unconsolidated, alluvial soil from Lazio, Italy, based on volcanic ash) and blue marlstone rocks (from Alba, Piedmont, north Italy) was measured, using a thermal probe technique, over a wide range of temperatures from ${-}20\,^\circ \mathrm{C}$ to ${+}20\,^\circ \mathrm{C}$ . Unfrozen pozzolanic soil thermal-conductivity data display surprisingly low values about 3 to 4 times smaller than water; for frozen soils, the data are just slightly higher than for the unfrozen state but they are still 2 to 3 times lower than for water and seven times lower than for ice. This outcome is probably due to a high internal porosity of individual volcanic ash particles. The influence of the bulk soil porosity on the measured thermal conductivity was found to be rather negligible; the observed slight variation of the thermal conductivity is possibly due to the diverse grain size distribution of soil samples excavated from different depths of the ground. The blue marlstone rock has a considerably higher thermal conductivity than pozzolanic soil, likely due to its very small porosity, consolidated structure, and different implicated minerals. The frozen rock has just about a 30 % higher thermal conductivity than that for the unfrozen state. A temperature-dependent thermal conductivity is observed in the freezing state only. Test results show how heat transfer between the thermal probe and surrounding soil is influenced by storage of heat in the tested material, conduction heat flow, water evaporation due to heating, and finally by vapor diffusion and circulation.     

Canadian Field Soils I. Mineral Composition by XRD/XRF Measurements

Forty Canadian soils were laboratory tested for the presence of quartz and other minerals using X-ray diffraction/X-ray fluorescence techniques. On average, the highest quartz content was observed in soil samples from sites in Nova Scotia followed by Prince Edward Island sites, whereas soil sample from British Columbia sites had the lowest quartz content. The second most abundant mineral was albite that mainly occurred in soil samples from Ontario and Quebec sites. Illite was the third most abundant and prevailed in soils mainly from British Columbia and New Brunswick sites. Soil samples from British Columbia sites had the highest combined clay and silt content and were composed of illite, albite, kaolinite, and chlorite. The lowest clay content was found in the samples from the Quebec sites. The highest microcline (a potassium feldspar) content was observed in Quebec, Ontario, and Prince Edward Island sites. In contrast to other provinces, samples from Quebec and Ontario sites also included amphibole. Soil samples from Saskatchewan and Manitoba sites also comprised carbonates, i.e., calcite and dolomite. Iron oxides (e.g., goethite) were present in all soils, except the Quebec sites, but their occurrence was rather insignificant.     

Correlating Thermal-Conductivity Data for Ternary Liquid Mixtures

The performance of several semi-empirical expressions for correlating the temperature, pressure and composition dependence of the thermal conductivity (λ) of pure organic liquids and mixtures was investigated. The temperature and pressure dependence is adequately represented by Chisholm approximants of order (1, 1) or (2, 1) with five and eight adjustable constants, respectively. The fully predictive Vredeveld equation uses mass fractions as the composition variable. It significantly underestimated λ values for the R32 + R125 + R134a ternary refrigerant system. Binary predictive models with one or two adjustable parameters include the quadratic Scheffé polynomial and its corresponding Padé approximant, the cubic “Margules” model and the theoretical Wassiljewa equation. It was found that the Padé (2, 2) approximant and the Wassiljewa equation satisfactorily correlated the extensive ternary mixture data published by Rowley and coworkers. Best results were obtained when the mole fraction was used as a composition variable. The predictive capability of the models was checked using the R32 + R125 + R134a ternary refrigerant system. Combining rules were used for cross parameters such that the temperature and pressure dependence was incorporated via the pure fluid properties. Model parameters were fixed using binary data alone. In this case, the quadratic Scheffé, Padé (2, 2), and Wassiljewa (with temperature- and pressure-independent parameters) all provided satisfactory predictions for ternary mixtures.     

Functional Identification of the Nonlinear Thermal-Conductivity Coefficient by Gradient Methods. II. Numerical Modeling

Algorithms for the gradient method of solution of the inverse problem on determination of the nonlinear thermal-conductivity coefficients are given. Results of numerical experiments are discussed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 4, pp. 75–81, July–August, 2005.     

Functional Identification of the Nonlinear Thermal-Conductivity Coefficient by Gradient Methods. I. Conjugate Operators

Consideration is given to the gradient methods of solution of the inverse heat-conduction problem on determination of the nonlinear coefficient λ(T) without its preliminary finite-dimensional approximation. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 4, pp. 68–74, July–August, 2005.     

Design and Validation of a High-Temperature Comparative Thermal-Conductivity Measurement System

A measurement system has been designed and built for the specific application of measuring the effective thermal conductivity of a composite, nuclear-fuel compact (small cylinder) over a temperature range of 100 °C to 800 °C. Because of the composite nature of the sample as well as the need to measure samples pre- and post-irradiation, measurement must be performed on the whole compact non-destructively. No existing measurement system is capable of obtaining its thermal conductivity in a non-destructive manner. The designed apparatus is an adaptation of the guarded-comparative-longitudinal heat flow technique. The system uniquely demonstrates the use of a radiative heat sink to provide cooling which greatly simplifies the design and setup of such high-temperature systems. The design was aimed to measure thermal-conductivity values covering the expected range of effective thermal conductivity of the composite nuclear fuel from 10 W . m⁻¹ . K⁻¹ to 70 W . m⁻¹ . K⁻¹. Several materials having thermal conductivities covering this expected range have been measured for system validation, and results are presented. A comparison of the results has been made to data from existing literature. Additionally, an uncertainty analysis is presented finding an overall uncertainty in sample thermal conductivity to be 6 %, matching well with the results of the validation samples.     

Modeling Discrete Bivariate Data with Applications to Failure and Count Data

In this study, we propose a new class of flexible bivariate distributions for discrete random variables. The proposed class of distribution is based on the notion of conditional failure rate for a discrete‐type random variable. We derive general formulae for the joint distributions belonging to the proposed class that, unlike other discrete bivariate models already proposed in the literature such as the well‐known and most popular Holgate's bivariate Poisson distribution, can model both positive and negative dependence. We discuss general statistical properties of the proposed class as well. Specific families of bivariate distributions can be generated from the general class proposed in this paper just by specifying the ‘baseline distributions’. Furthermore, specific discrete bivariate distributions belonging to the proposed class are applied to analyze three real data sets, and the results are compared with those obtained from conventional models. Copyright © 2017 John Wiley & Sons, Ltd.     

Aphanomyces euteiches: A Threat to Canadian Field Pea Production

Field pea (Pisum sativum var. arvense L.) is an important legume crop around the world. It produces grains with high protein content and can improve the amount of available nitrogen in the soil. Aphanomyces root rot (ARR), caused by the soil-borne oomycete Aphanomyces euteiches Drechs. (A. euteiches), is a major threat to pea production in many pea-growing regions including Canada; it can cause severe root damage, wilting, and considerable yield losses under wet soil conditions. Traditional disease management strategies, such as crop rotations and seed treatments, cannot fully prevent ARR under conditions conducive for the disease, due to the longevity of the pathogen oospores, which can infect field pea plants at any growth stage. The development of pea cultivars with partial resistance or tolerance to ARR may be a promising approach to analyze the variability and physiologic specialization of A. euteiches in field pea and to improve the management of this disease. As such, the detection of quantitative trait loci (QTL) for resistance is essential to field pea-breeding programs. In this paper, the pathogenic characteristics of A. euteiches are reviewed along with various ARR management strategies and the QTL associated with partial resistance to ARR.     

Mathematical Modeling of the Processes of Deformation of Soils with Time

It has been suggested that the rheological properties of soils be modeled by the integral Volterra equation of the second kind of the nonlinear heredity theory and by the differential equation which, under certain conditions, approximately replaces the adopted integral equation. Parameters of these governing equations have been found from experimental data for a number of soils. The processes of creep of soils have been studied.     

Property Modeling across Transition Temperatures in PMC's: Part III. Bending Fatigue

Parts I [1] and II [2] of the present paper introduced systematic models for the computation of thermal effects on strength and stiffness of unidirectional polymer matrix composites (PMC's) as well as the life prediction of these materials in end-loaded bending at elevated temperatures. The last step of this study was the possibility of introducing such models in durability codes such as MRLife [3]. A recent method was developed for the experimental characterization of end-loaded bending fatigue behavior of composites at elevated temperatures. The literature dealing with the durability of composite materials in bending focuses mainly on 3 and 4 point bending [4–6]. A limited set of data as well as the basis for theoretical modeling for fatigue end-loaded bending is available in the literature [7]. However, the life prediction scheme required elevated temperature experiments. New experiments in fatigue bending were performed in order to complete the available data. Microscopic observations revealed new information for the understanding of the damage process of unidirectional AS4/PPS composites in end-loaded fatigue bending. Finally, the models developed in Parts I and II were integrated into the MRLife integral enabling the life prediction of unidirectional PMC's under combined mechanical and thermal loads from room temperature experimental data.     

短裂纹密度场建模与CT成像仿真

以不同时刻的短裂纹密度场CT仿真成像为研究对象,提出了密度场建模原理,得到了局部质量不守恒和局部质量守恒两种裂纹扩展模型;利用亚体素模型、裂纹离散化、亚体素级的短裂纹扩展算法并扩展了建模软件的文件建模功能,分别得到了相应的CT检测样本模型文件,实现了局部质量不守恒和局部质量守恒两种情形下的裂纹扩展建模;通过获取不同时刻的CT检测样本模型文件,利用CT仿真系统重建了不同时刻的密度场图像,建立了不同裂纹扩展阶段的演化记录.     

Source Field Modeling by Mesh Incidence Matrices

In this paper, an algorithm using mesh incidence matrices is developed for the fast generation of source magnetic fields. The mesh incidence matrices arise by applying cohomology concepts to the discrete form of the topological laws for source magnetic fields. The algorithm admits a unique and very fast integer Gaussian elimination procedure. The same algorithm is used to generate solenoidal current density in stranded conductors     

基于Excel的加油机现场检定数据处理

燃油加油机的检定要求在现场短时间内处理大量的原始数据,快速判别油机是否合格,应用Excel将需要计算的函数编辑好,装于随身携带的智能手机上,既方便又能应用Excel提高计算的速度和准确度,有效的提高检定效率和服务质量。