Методичні вказівки і контрольні завдання з курсу "Високотемпературні теплотехнологічні установки"

Високотемпературні процеси є основними робочими процесами в ряді технологічних виробництв, таких, як виробництво коксу, чавуну, сталі та кольорових металів, випал кераміки і вогнетривів, випал в’яжучих матеріалів, варіння скла, високотемпературне нагрівання злитків, отримання агломерату, феросплавів та ін. У процесі вивчення дисципліни «Високотемпературні установки» (ВТУ) необхідно освоїти методи практичного розрахунку теплового стану злитка в процесі нагрівання, визначити вплив окремих факторів на калориметричну, а відповідно і на пірометричнy температуру горіння. Вміти самостійно вибрати вогнетривкі та ізоляційні матеріали для печі заданих розмірів і теплотехнологічних умов, скласти тепловий баланс печі і визначити годинну, секундну та питому витрату заданого і умовного палива. Для термічної соляної печі з електричним нагріванням визначити час розігріву печі з холодного стану при використанні в кладці різних вогнетривів. Зіставити результати розрахунку і оцінити енергоефективність заходів. Усі завдання оформляються на аркушах формату А4 або в окремих зошитах

Structure formation in active networks

Structure formation and constant reorganization of the actin cytoskeleton are key requirements for the function of living cells. Here we show that a minimal reconstituted system consisting of actin filaments, crosslinking molecules and molecular-motor filaments exhibits a generic mechanism of structure formation, characterized by a broad distribution of cluster sizes. We demonstrate that the growth of the structures depends on the intricate balance between crosslinker-induced stabilization and simultaneous destabilization by molecular motors, a mechanism analogous to nucleation and growth in passive systems. We also show that the intricate interplay between force generation, coarsening and connectivity is responsible for the highly dynamic process of structure formation in this heterogeneous active gel, and that these competing mechanisms result in anomalous transport, reminiscent of intracellular dynamics

Collective dynamics of active cytoskeletal networks

Self organization mechanisms are essential for the cytoskeleton to adapt to the requirements of living cells. They rely on the intricate interplay of cytoskeletal filaments, crosslinking proteins and molecular motors. Here we present an in vitro minimal model system consisting of actin filaments, fascin and myosin-II filaments exhibiting pulsative collective long range dynamics. The reorganizations in the highly dynamic steady state of the active gel are characterized by alternating periods of runs and stalls resulting in a superdiffusive dynamics of the network's constituents. They are dominated by the complex competition of crosslinking molecules and motor filaments in the network: Collective dynamics are only observed if the relative strength of the binding of myosin-II filaments to the actin network allows exerting high enough forces to unbind actin/fascin crosslinks. The feedback between structure formation and dynamics can be resolved by combining these experiments with phenomenological simulations based on simple interaction rules

Thermal conduction in cosmological SPH simulations

Thermal conduction in the intracluster medium has been proposed as a possible heating mechanism for offsetting central cooling losses in rich clusters of galaxies. In this study, we introduce a new formalism to model conduction in a diffuse ionised plasma using smoothed particle hydrodynamics (SPH), and we implement it in the parallel TreePM/SPH-code GADGET-2. We consider only isotropic conduction and assume that magnetic suppression can be described in terms of an effective conductivity, taken as a fixed fraction of the temperature-dependent Spitzer rate. We also account for saturation effects in low-density gas. Our formulation manifestly conserves thermal energy even for individual and adaptive timesteps, and is stable in the presence of small-scale temperature noise. This allows us to evolve the thermal diffusion equation with an explicit time integration scheme along with the ordinary hydrodynamics. We use a series of simple test problems to demonstrate the robustness and accuracy of our method. We then apply our code to spherically symmetric realizations of clusters, constructed under the assumptions of hydrostatic equilibrium and a local balance between conduction and radiative cooling. While we confirm that conduction can efficiently suppress cooling flows for an extended period of time in these isolated systems, we do not find a similarly strong effect in a first set of clusters formed in self-consistent cosmological simulations. However, their temperature profiles are significantly altered by conduction, as is the X-ray luminosity.Comment: 14 pages, 7 figures, accepted by MNRAS, high resolution version available at http://www.mpa-garching.mpg.de/~jubelgas/conduction.pdf. Fixed typos in eq. 20,22,2

Morphological Multiscale Shape Analysis of Light Micrographs

Shape analysis of light--micrographs of cell populations is important for cytotoxicity evaluation. This paper presents a morphological method for quantitative analysis of shape deformations of cells in contact to a biomaterial. After illumination normalization, a morphological multiscale segmentation yields separated cells. Shape deformation, and hence, toxicity of the substance under scrutiny, is quantified by means of compactness distribution and pattern spectrum of the population. Since the logarithmic image model is applicable to transmitted light, illumination normalization is achieved by removing the illumination component from the log--image by a tophat transform utilizing a large reconstruction filter. Subsequent thresholding and noise filtering yields connected binary cells, which are segmented by a marker--based, multiscale approach. For this, size--specific marker scales are generated removing noise and false markers. Each cell is now represented by an isolated marker. Conve..