Phonon scattering in ortho-para hydrogen solid solutions (role of configurational relaxation)

The experimental data on the thermal conductivity of ortho-parahydrogen solutions are analyzed on the basis of a relaxation-time model taking account of configurational relaxation of the ortho subsystem. The influence of configurational relaxation on the thermal conductivity is analyzed using resonance scattering of phonons by pair clusters of orthomolecules taking account of their rotational spectrum.Comment: 7 pages, 4 figure

Компьютерное моделирование ветровых нагрузок на высотные здания

The paper presents the results of numerical simulation of wind pressure on high rise buildings being under construction and planned in Yekaterinburg city (Russia). Simulation is performed in the program ANSYS. The simulated building is placed in a domain that is the numerical analogue of wind tunnel. Domain sizes are chosen in such a way that simulated buildings do not affect the flow of air on its boundaries. Shear stress transport (SST) turbulence model is used. In order to validate the numerical model the paper presents the results of experimental study and numerical simulation of external air flow around the cylindrical body with the diameter of 8 mm, placed on the way of free submerged jet of air. The cylinder which has simple geometry form was used due to the need to achieve the generality of the outcomes. A comparison of the results of calculation of wind pressure with the experimental data blasting building models in wind tunnels is done.В статье представлены результаты численного моделирования задачи определения ветровых давлений на строящиеся или проектируемые в г. Екатеринбурге (Россия) высотные здания. Задача решается в пакете ANSYS. Моделируемое здание и его окружение помещаются в домен, который является численным аналогом ветровой трубы. Размеры домена назначаются таким образом, чтобы объекты, входящие в домен, не влияли на движение воздуха у внешних границ домена. Для расчета используется модель SST. Для проверки правильности численной модели приводится сравнение результатов расчета с экспериментальными данными обдувки цилиндра диаметром 8 мм. Такая модель простой формы выбрана для удобства сравнения. Приведено сравнение численных результатов расчета давлений ветра на высотные здания с результатами обдувки в ветровых трубах

Thermal Conductivity of Methane-Hydrate

The thermal conductivity of the methane hydrate CH4 (5.75 H2O) was measured in the interval 2-140 K using the steady-state technique. The thermal conductivity corresponding to a homogeneous substance was calculated from the measured effective thermal conductivity obtained in the experiment. The temperature dependence of the thermal conductivity is typical for the thermal conductivity of amorphous solids. It is shown that after separation of the hydrate into ice and methane, at 240 K, the thermal conductivity of the ice exhibits a dependence typical of heavily deformed fine-grain polycrystal. The reason for the glass-like behavior in the thermal conductivity of clathrate compounds has been discussed. The experimental results can be interpreted within the phenomenological soft-potential model with two fitting parameters.Comment: 13 pages, 3 figure

Diffusion model of the thermal conductivity plateau of weak solid solutions of neon in parahydrogen

The diffusion kinetic of classic impurity particles has been investigated in the frame of one-dimensional two-level model and applied for the explanation of solid hydrogen thermal conductivity data with extremely low con-centrations of neon impurity in samples growth at different crystallization rates in which the plateau effect was observed. The main idea is that heavy isotopic impurities could segregate into thin long chains near dislocation cores if the growth rate is slow. Neon impurity chains can persist for a long time. Such rigid linear objects ensure inelastic scattering of phonons. The diffusion coefficient of neon atoms in (p-H₂)₁–cNec mixtures was estimated for the experimental conditions with с = 0.0001 аt. % and с = 0.0002 аt. %

Thermal conductivity of solid krypton with methane admixture

The thermal conductivity of CH₄–Kr solid solutions is investigated at CH₄ concentrations 0.2–5.0% in the temperature range 1.8–40 K. It is found that the temperature dependence of the thermal conductivity has features typical of resonance phonon scattering. The analysis of the experimental results shows that the main contribution to the impurity-caused scattering of phonons is made by the scattering on rotational excitations of the nuclear spin T-species of CH₄ molecules. The phonon–rotation interaction parameter is estimated

Defects search during the inspection of civil and industrial buildings and structures on the basis of laser scanning technology and information modeling approach (BIM)

This paper presents the issues of the inspection, creation of drawings and 3D model of the building in the absence thereof a technical documentation for the object of reconstruction. An approach based on the use of laser scanning technologies and information modeling of objects is proposed. The laser scanning of facades of residential buildings, objects of cultural heritage, industrial enterprises is considered. The proposed approach makes it possible to improve safety during the work on the inspection of building structures, to execute a construction project drawings and specifications with the maximum degree of detail. On the basis of the created three-dimensional model of the object it is possible to subsequently make a static calculation of the building’s structures