What causes natural durability in Eucalyptus bosistoana timber?

This study investigated the natural durability of 8 and 60 year old Eucalyptus bosistoana (coast grey box). The sample’s heartwood compounds were extracted with an optimised extraction process and then incorporated into agar. Trametes versicolor (white rot) and Gloeophyllum trabeum (brown rot) fungi were grown upon these agars and their growth rate was used to assess the fungicidal abilities of the extracts. The extraction method of cell wall compounds was optimised. An Accelerated Solvent Extraction system (ASE) was used with the following settings: • 2 cycles per sample • 70°C extraction temperature • 50% rinse • 5 minute static time Ethanol was found to extract the compounds of the highest fungicidal activity. Ethanol was found to extract similar amounts to water (~13% of dry weight for a 60 year old sample), however analysis of both water and ethanol extracts with a FTIR spectrometer, found that they were of different chemical composition. A difference in fungicidal activity of extracts was found between the 8 year old and 60 year old samples. There was a large difference in the percentage of extracts present between the samples as well as the type of compounds present, shown by FTIR

Theoretical determination of surface roughness during high-speed milling and grinding

Аналитически установлено, что высокоскоростное фрезерование располагает значительными технологическими возможностями с точки зрения уменьшения шероховатости поверхности при одновременном увеличении производительности обработки. Установлено также, что при шлифовании уменьшение шероховатости поверхности связано с уменьшением производительности. Наиболее прогрессивным методом шлифования, обеспечивающим одновременно увеличение производительности и уменьшение шероховатости поверхности, является глубинное шлифование с небольшой скоростью детали, которое характеризуется меньшей производительностью по сравнению с высокоскоростным фрезерованием.The paper presents the results of theoretical studies of the surface roughness during milling and grinding. It is shown that high-speed milling has significant technological capabilities in terms of reducing surface roughness, because cutting data parameters are included in the calculated dependencies obtained to determine surface roughness with higher degrees than during grinding. This applies in particular to the speed of rotation of the cutter. Therefore, with its increase, it becomes possible to significantly reduce the surface roughness while increasing the processing capacity, which opens up broad prospects for the practical use of high-speed milling. It is established that during grinding, a decrease in surface roughness is associated with a decrease in productivity, and this reduces the efficiency of processing. The most progressive method of grinding, providing b oth an increase in productivity and a reduction in surface roughness, is deep-grinding at a low speed of the part. However, it is characterized by lower productivity in comparison with high-speed milling

Разработка архитектуры и программных средств витрин данных для предприятия нефтегазовой отрасли

Анализируются проблемы создания отраслевых информационно-аналитических систем, основанных на современных OLAP-технологиях. Рассмотрен вариант архитектуры хранилища данных для крупного нефтегазодобывающего предприятия на примере проектирования тематической витрины данных, включающего анализ специфической предметной области, проектирование многомерных структур данных, постановку аналитических задач и их решение

Mathematical modeling of thermal power plant's boiler air-gas flow path regulation modes

В работе предлагаются математические модели газовоздушного тракта котла и механизмов собственных нужд ТЭС. С использованием табличных и графических представлений напорных характеристик серийных вентиляторов и дымососов получены эквивалентные соотношения для сети механизмов. Исследована задача нахождения оптимальных параметров управления для группы центробежных механизмов, обеспечивающих работу газовоздушного тракта котла. Исследовано влияние разрежения в топке котла на режим работы его вспомогательных механизмов. Приводятся результаты моделирования для типичных последовательно-параллельных соединений механизмов в гидравлических сетях ТЭС.The paper presents a mathematical model for thermal power plant's boiler air-gas flow paths and auxiliaries. With application of production fans' and flue gas extractor fans' head-capacity curves and tables, equivalent relations for the net of the mechanisms are obtained. A problem of determining the optimal control parameters for a group of centrifugal mechanisms in the air-gas path is studied. The effect of the boiler furnace draft on its auxiliaries operation is analyzed. The results of mathematical modeling for typical serial and parallel connections of the mechanisms in the thermal power plant hydraulic network are given

Precast concrete floor support and diaphragm action

Experimental research, engineering analysis and theoretical developments comprise a study in which various interactions between ductile moment resisting frames and precast prestressed hollow core flooring have been examined. The most critical interaction tested involves support behaviour, and the ability of reinforcing details to provide control against loss of support and possible catastrophic flooring collapse under dilation effects. Plastic hinge dilation, also known as elongation or growth, is an inherent property of ductile concrete members when subjected to cyclic plastic deformations. Hence, the performance of floor support details is enveloped by the general design philosophy of seismic resisting structures. In the experimental phase, emphasis was placed on testing support construction joints from contemporary building practice, for direct comparison with special support tie details of known capabilities. The contemporary details were found to exhibit seriously flawed behaviour under monotonic and cyclic loading regimes. Corroborative experiments were undertaken to establish direct shear capacities between typical composite bond surfaces. In particular, these tests addressed the discrepancy that has emerged between direct shear and shear flow strengths. Also, the continuity response of conventional and proposed support detail types was examined. A composite section model was analysed to demonstrate the likely influence of prestressing steel on beam bending strength within a ductile frame environment. Likewise, the probable effects of prestressing steel on beam plastic hinge development were examined, but on a more theoretical basis. Other elements of theory have been presented. These mainly concern the general topic of elastic-plastic response in reinforced concrete elements. The particular focus of this work has been to demonstrate a rational basis to stiffness transition and plastic buckling analysis. The important role of stiffness degradation in dynamic analysis has also been examined. Although ductile moment resisting concrete frames have been emphasised, it is considered that the findings of this thesis are applicable to other structural systems, such as dry joint "hybrid" precast concrete frames and spring connected steel frame structures

Motivation and its importance in learning English

The principal objective of this paper is to pay our attention to such a significant problem as motivation in the process of learning a foreign language. The paper is devoted to the very important problem concerning educational process. For most purposes in today, motivation has different reasons why we act in a certain way. We may indeed be motivated by influences as basic as pain and pleasure. The key to understanding motivation is, to some, understanding why it is important to an individual or to a group or organization. In this case some definitions of motivation are given. Also the paper pinpoints attention upon the ways the teacher can use to level up the student's desire to study language