Термопружний стан шаруватих термочутливих циліндрів і куль за конвективно-променевого теплообміну

Розроблено методику розв’язування одновимірних статичних задач термопружності для шаруватих циліндрів і куль за конвективно-променевого нагрівання з урахуванням лінійної залежності коефіцієнтів теплопровідності та довільного характеру залежності інших фізико-механічних характеристик від температури. Задачі теплопровідності зведено, незалежно від кількості шарів, до розв’язування системи двох нелінійних алгебричних рівнянь. У задачах термопружності неперервні в межах кожного шару коефіцієнти рівнянь апроксимовано кусково-сталими функціями. Проведено числовий аналіз температурних полів і напружень у двошарових тілах.The method for solving one-dimensional static thermoelasticity problems is developed for layered cylinders and spheres under convective and radiation heating, taking into account linear dependence of heat conductivity coefficients and arbitrary character of dependence of other physical and mechanical characteristics on a temperature. Problems of heat conductivity have been reduced to the system of two nonlinear algebraic equations regardless of the number of layers. In the thermoelasticity problems the continuous within every layer coefficients of equations are approximated by piecewise constant functions. The numerical analysis of the temperature fields and stresses is conducted for two-layered bodies.Разработана методика решения одномерных статических задач термоупругости для слоистых цилиндров и сфер при конвективно-лучевом нагреве с учетом линейной зависимости коэффициентов теплопроводности и произвольного характера зависимости других физико-механических характеристик от температуры. Задачи теплопроводности сведены, независимо от количества слоев, к решению системы двух нелинейных алгебраических уравнений. В задачах термоупругости непрерывные в пределах каждого слоя коэффициенты уравнений аппроксимированы кусочно-постоянными функциями. Проведен численный анализ температурных полей и напряжений в двухслойных телах

Распределение металлической фазы в синтетических алмазах типа «карбонадо»

Studying of a structural structure synthetic «carbonado» is spent by a method of electronic scanning microscopy. It is established, that the surface «carbonado» is covered by the large diamond crystals reaching 200 microns, having obviously expressed structure of growth. On a surface of these crystals observed drops of metal-catalyst (nickel) of a submicronic range. It is established, that the structure synthetic «carbonado» represents interpenetrating skeletons from diamond and ceramic-metal phases

Connecting the data landscape of long-term ecological studies: The SPI-Birds data hub

The integration and synthesis of the data in different areas of science is drastically slowed and hindered by a lack of standards and networking programmes. Long-term studies of individually marked animals are not an exception. These studies are especially important as instrumental for understanding evolutionary and ecological processes in the wild. Furthermore, their number and global distribution provides a unique opportunity to assess the generality of patterns and to address broad-scale global issues (e.g. climate change). To solve data integration issues and enable a new scale of ecological and evolutionary research based on long-term studies of birds, we have created the SPI-Birds Network and Database (www.spibirds.org)\u2014a large-scale initiative that connects data from, and researchers working on, studies of wild populations of individually recognizable (usually ringed) birds. Within year and a half since the establishment, SPI-Birds has recruited over 120 members, and currently hosts data on almost 1.5 million individual birds collected in 80 populations over 2,000 cumulative years, and counting. SPI-Birds acts as a data hub and a catalogue of studied populations. It prevents data loss, secures easy data finding, use and integration and thus facilitates collaboration and synthesis. We provide community-derived data and meta-data standards and improve data integrity guided by the principles of Findable, Accessible, Interoperable and Reusable (FAIR), and aligned with the existing metadata languages (e.g. ecological meta-data language). The encouraging community involvement stems from SPI-Bird's decentralized approach: research groups retain full control over data use and their way of data management, while SPI-Birds creates tailored pipelines to convert each unique data format into a standard format. We outline the lessons learned, so that other communities (e.g. those working on other taxa) can adapt our successful model. Creating community-specific hubs (such as ours, COMADRE for animal demography, etc.) will aid much-needed large-scale ecological data integration

Practical applications of multivariate statistics in exploration geochemistry

The search for new economic ore-deposits becomes increasingly difficult. A sophisticated approach is required to locate new ones. In exploration geochemistry the use of uni- and multivariate statistics is often advocated. In this series of studies it is shown how techniques such as factor analysis, discriminant function analysis, non linear mapping and cluster analysis can be of use to the exploration geochemist. Applications are presented to geochemical rock, sediment and water surveys

Practical applications of multivariate statistics in exploration geochemistry

The search for new economic ore-deposits becomes increasingly difficult. A sophisticated approach is required to locate new ones. In exploration geochemistry the use of uni- and multivariate statistics is often advocated. In this series of studies it is shown how techniques such as factor analysis, discriminant function analysis, non linear mapping and cluster analysis can be of use to the exploration geochemist. Applications are presented to geochemical rock, sediment and water survey

Petrography and geochemistry of flint from the Lanaye chalk (Rijckholt-St. Geertruid), and some other neolithic sources

Met lit. op

An application of lithogeochemistry to the evaluation of the Ni-sulphide ore potential of weathered serpentinites in the Fortaleza de Minas Greenstone Belt, Minas Gerais, Brazil

A practical application of lithogeochemistry to the classification of weathered serpentinites as to whether or not serpentinites are host rocks to Ni-sulphide ore is presented. An effort is made to apply existing concepts used to distinguish between fertile and sterile unweathered ultramafics to explain the observed chemical differences between fertile and sterile weathered serpentinites in southwestern Minas Gerais, Brazil. The data comprise total-attack chemical analyses for Al, Ca, Cr, Cu, Fe, Mg, Mn, Ni, Si, Ti, V, and partial-attack determinations of Cu and Ni as ascorbic acid, hydrogen peroxide-soluble metal. Student's t-tests are used to identify element concentration differences between the two serpentinite groups. Discriminant analysis is used to classify the weathered fertile and sterile serpentinites. Non-linear mapping and fuzzy c-means clustering help to assess the validity of the discriminant analysis. Finally, chemical element associations provide extra information on geological and mineralogical causes that can be responsible for the identified differences. It is found that a clear separation and classification of weathered serpentinites is possible using the procedures presented. The observed chemical differences between fertile and sterile serpentinites are interpreted in terms of original magmatic differentiation, the degree of sulphur saturation of the original magma and the behavior of the derived ultramafic rocks in a tropical weathering environment

Feldspar weathering as the key to understanding soil acidification monitoring data; a study of acid sandy soils in the Netherlands

Monitoring activities pose special demands on the type of survey results needed. In the early 1990s a soil acidification monitoring methodology was adopted in the Netherlands that leaned heavily on methods developed in more fundamental research, most notably the use of proton budgets. Consequently, various controversies still not resolved in the scientific debate reflect on the current practice of soil acidity monitoring and complicate interpretation of the monitoring results. In a pilot study we address the most pressing issues: capacity versus intensity parameters, choice of monitoring objective, and natural variation in the compartment to be monitored. Focus is on the major source of buffering, the possible usefulness of the historic approach, and the regional patterns present in the sandy soils of the Netherlands. In a field campaign 92 locations in sandy regions all over the country were sampled at two depths. The solid phase, the displaced soil solution, and solid phase extractions with 0.01 M CaCl2 and 0.43 M HNO3, for the 184 samples were analyzed by a variety of methods. Aluminum release is the major source of buffering and is shown to contribute substantially to acid buffering already under natural conditions. The predominant Al bearing phases in Dutch sandy soils are feldspars and secondary Al minerals; feldspars are found to be the determinative phase in acid buffering. Application of the historic approach using the subsoil as a proxy for the initial composition of the topsoil proved feasible for this regional dataset. The average depletion of the ANC(s) of 230 mmolc kg¿1 in the topsoil matches well with estimates of the total proton load since the last ice age, with the anthropogenic contribution being between 20% and 50%. Fuzzy c-means cluster analyses of the solid phase and soil solution data show a distinct regionality that was also reflected in the parameters generally used to indicate the acidity status of soils, ¿ANC(s) and Al/BC ratios. A combined insight into both solid phase and soil solution, based on a comprehensive set of parameters, proves essential for interpreting soil acidity monitoring data

Effects of site lithology on geochemical signatures of human occupation in archaeological house plans in The Netherlands

This study presents the application of multi-element soil analyses (X-ray fluorescence spectroscopy and inductively coupled plasma optical emission spectroscopy of 1 M HCl extracts) to grid samples from 3 archaeological house plans embedded in sandy clays, clays and sands to assess effects of site lithology on geochemical signatures of human occupation. The results indicate that this effect is significant and that each house plan is characterized by enhanced concentrations of different sets of elements. Copper, Cr, Sn and Nd enrichments were found at all sites and thus represent elements that have no or only a weak relation with lithology. Depletions of Fe and Mn were also found to be universal indicators of human occupation in the house plans. A combination of off-site sampling, comparison to regional element background concentrations and the use of bivariate plots (Al vs selected elements) was successfully applied to identify anthropogenic elements, verify background element concentrations and element sources, and assess element distribution patterns within house plans. Spatial patterning of several anthropogenic elements suggest the presence of an in-house barn at two sites, while for another site no spatial patterning of chemical elements was observed. For two sites this contrasts with earlier archaeological interpretation. Our results further suggest that 1 M HCl extractable elements are unreliable indicators of human occupation in clayey and especially calcareous clayey soils. © 2009 Elsevier Ltd. All rights reserved

The effect of naturally acidified irrigation water on agricultural volcanic soils. The case of Asembagus, Java, Indonesia

Acid water from the Banyuputih river (pH similar to 3.5) is used for the irrigation of agricultural land in the Asembagus coastal area (East Java, Indonesia), with harmful consequences for rice yields. The river water has an unusual composition which is caused by seepage from the acidic Kawah Ijen crater lake into the river. This unique irrigation setting allows the study of soil acidification in situ. This paper assesses the effects of volcanogenically contaminated irrigation water on the chemical properties of the agricultural soils. The changes in soil properties were evaluated by comparing samples taken from the topsoil and sub-soil (1-3 m depth) from areas irrigated with acid water and areas irrigated with neutral water. The field survey thus resulted in four soil categories. Bulk soil composition, organic matter content, moisture content and particle size distribution were determined. Reactive phases were quantified with the selective extractions 1 M KCl, 0.1 M Na-pyrophosphate and 0.2 M acid ammonium oxalate (AAO). By comparing the four soil categories it is shown that the use of the naturally polluted irrigation water has had a large influence on the chemical composition of the topsoil. The composition of the soil solution has changed over the entire investigated soil profile. Furthermore the acid irrigation water has strongly modified the composition of the reactive phases, extracted as KCl, pyrophosphate, and AAO extractable elements, and also the bulk soil composition has been significantly modified. Overall this has resulted in the net dissolution of some elements and the net precipitation of others. The changes in the reactive phases and bulk soil composition are only apparent in the topsoil (0-20 cm) but not in the deeper soil