Rational design of hybrid polymetallic structures taking into account mass loads

Рассмотрена проблема рационального (оптимального) проектирования высотных или административно-управленческих сооружений при активном использовании гибридных полиметаллических стандартизированных элементов, создаваемых на основе различных надежно разработанных технологий. Целью решения проблемы является подбор и перераспределение материалов, при которых с обеспечением требуемых комфортных и безопасных условий существования будут значительно улучшены экономические показатели создаваемого проекта. В качестве гарантированных требований комфортного существования использованы разработанные автором три различия критерия деформативности фазовых материалов в условиях заданных типов и полей внешних нагрузок. Первый критерий: «предельно допустимое упругое состояние» - когда ни один из фазовых материалов не будет деформироваться за пределом упругости. Второй критерий: «предельно допустимые деформации упрочнения» - когда фазовые материалы не переходят в состояние разупрочнения. Третий критерий: «предельно допустимые деформации разрушения» - когда какой-либо из фазовых материалов будет «локально» разрушаться. При расчетах учитывается, что ряд физических характеристик материалов в широких пределах технологических переработок довольно устойчиво сохраняют свои значения и используются как заранее известные данные из справочной литературы. К ним относятся пределы упругости и прочности, модули Юнга, удельные плотности и стоимости фазовых материалов. Такая малочувствительная технологическая устойчивость позволила для всех фазовых материалов при аппроксимации диаграммы деформирования различных металлических материалов использовать единообразную зависимость в виде кубической параболы, коэффициенты которой и упомянутые три предельно допустимые деформации выражаются через устойчивые характеристики - пределы упругости, прочности и модуль Юнга. На основе известных кинематических и статических гипотез описания неупругого деформирования стержневых систем для всех типов предельно-допустимых деформаций, получены единообразные системы уравнений, которые позволяют для заданных условий внешнего воздействия определить геометрические параметры и топологическую структуру распределения всех фазовых материалов по конструкции. В качестве внешних воздействий на конструкцию высотного сооружения рассматриваются традиционные ветровые нагрузки с заданным законом изменения вдоль вертикальной оси, заданные моменты и силы на верхнем вертикальном срезе и изменяемые при топологических перераспределениях массовые нагрузки. Степень усовершенствования проекта оценивается на основе анализа изменения введенных относительных характеристик несущей способности, податливости и стоимости проекта. Для сравнения используется эталонный проект из однородного материала. The problem of rational (optimal) design of high-rise or administrative and management structures with the active use of hybrid polymetallic standardized elements, created on the basis of various reliably developed technologies, is considered. The purpose of solving the problem is the selection and redistribution of materials, in which, with the provision of the required comfortable and safe conditions of existence, the economic indicators of the project being created will be significantly improved. Three differences in the deformability criterion of phase materials under conditions of specified types and fields of external loads, developed by the author, were used as guaranteed requirements for comfortable existence. The first criterion: "maximum permissible elastic state when none of the phase materials will deform beyond the elastic limit. The second criterion: "maximum permissible hardening deformations when phase materials do not pass into a softening state. The third criterion: "maximum permissible fracture strains when any of the phase materials will "locally"fail. The calculations take into account that a number of physical characteristics of materials in a wide range of technological processing rather stably retain their values and are used as data known in advance from the reference literature. These include the limits of elasticity and strength, Young’s moduli, specific densities and costs of phase materials. Such a low-sensitivity technological stability made it possible for all phase materials to use a uniform dependence in the form of a cubic parabola for approximating the deformation diagram of various metallic materials, the coefficients of which and the above three maximum permissible deformations are expressed in terms of stable characteristics - the limits of elasticity, strength and Young’s modulus. On the basis of the known kinematic and static hypotheses of the description of inelastic deformation of rod systems for all types of maximum permissible deformations, uniform systems of equations are obtained that allow for the given conditions of external action to determine the geometric parameters and the topological structure of the distribution of all phase materials over the structure. Traditional wind loads with a given law of variation along the vertical axis, given moments and forces on the upper vertical cut, and mass loads varying during topological redistributions are considered as external influences on the structure of a high-rise structure. The degree of improvement of the project is estimated based on the analysis of changes in the entered relative characteristics of bearing capacity, flexibility and cost of the project. For comparison, a reference design from a homogeneous material is used.

Secular polar motion observed by GRACE

A long-term drift in polar motion (PM) has been observed for more than a century, and Glacial Isostatic Adjustment (GIA) has been understood as an important cause. However, observed PM includes contributions from other sources, including contemporary climate change and perhaps others associated with Earth’s interior dynamics. It has been difficult to separate these effects, because there is considerable scatter among GIA models concerning predicted PM rates. Here we develop a new method to estimate GIA PM using data from the GRACE mission. Changes in GRACE degree 2, order 1 spherical harmonic coefficients are due both to GIA and contemporary surface mass load changes. We estimate the surface mass load contribution to degree 2, order 1 coefficients using GRACE data, relying on higher-degree GRACE coefficients that are dominantly affected by surface loads. Then the GIA PM trend is obtained from the difference between observed PM trend (which includes effects from GIA and surface mass loads) and the estimated PM trend mostly associated with surface mass loads. A previous estimate of the GIA PM trend from PM observations for the period 1900–1978 is toward 79.90° W at a speed of 3.53 mas/year (10.91 cm/year). Our new estimate for the GIA trend is in a direction of 61.77° W at a speed of 2.18 mas/year (6.74 cm/year), similar to the observed PM trend during the early twentieth century. This is consistent with the view that the early twentieth-century trend was dominated by GIA and that more recently there is an increasing contribution from contemporary surface mass load redistribution associated with climate change. Our GIA PM also agrees with the linear mean pole during 1900–2017. Contributions from other solid Earth process such as mantle convection would also produce a linear trend in PM and could be included in our GIA estimate.

Microwave dehydration of potato slices and assessment of energy efficiency

The dehydration parameters (thickness, mass load, and power level) statistically significantly (p<0.05) affect the microwave dehydration of potato slices. Potato slices with thicknesses of 3, 6, and 9 mm were dehydrated as monolayers at different mass loads (1.00, 0.63, and 0.38 kg m-2) and microwave power levels (80, 240 W). The optimal model of potato slices with a 3 mm thickness, 0.38 kg m-2 mass load, dehydrated on 240 W, had the shortest dehydration time (15 minutes), the most negligible energy consumption (0.064 kWh), and the most insignificant emission of carbon dioxide (0.063 kg). The model of potato slices of 9 mm slice thickness dehydrated on 240 W, with 0.38 kg m-2 mass load, showed the highest resistance to mass transfer (the maximum effective moisture diffusivity 1.1847 × 10-7 ± 2.6080 × 10-9 m2 s-1). The average activation energy for all models was determined to be 11.635 W g-1. The thinner potato slices showed better results in dehydration time and energy consumption and good moisture diffusivity.