Papers by Keyword: Self-Organization

Abstract: Based on the analysis of the defect formation in silicon carbide polytypes in different semiconductor manufacturing processing steps, device operation and environmental-device interaction it is concluded that external material and energy fluxes are generally able to destabilize the polytype structure. The governing reason is the formation of stacking faults and instabilities of the partial dislocation associated with them. A new ansatz is proposed to describe the structural instabilities using none-equilibrium thermodynamics and the entropy production. A criterial form for polyype transitions is proposed. The developed criterial form is applied to describe observed structural instabilities occur­ring under different external actions.

Abstract: The research presented in this scientific paper focuses on modeling the dynamics of multicomponent systems with particles of different geometries using the GROMACS software package. Three main types of particles were analyzed in the study: spheres, ellipsoids, and plates, each of which has its own unique geometric characteristics that affect their behavior in the environment. The modeling allowed us to investigate the influence of particle shape on their diffusion, self-organization, and interaction between particles of different shapes. In particular, spherical particles, having an isotropic geometry, show the highest diffusion coefficient, since their symmetrical structure minimizes the resistance of the environment. This, in turn, makes them ideal for modeling simple interactions in liquids or colloids. Ellipsoidal particles, due to their anisotropy, have a slightly reduced diffusion coefficient, since their orientation in space affects the motion. Plates, which have a significant surface area relative to the volume, demonstrate the lowest diffusion rate, which is associated with a large interaction with the environment and the resistance created by their geometry. The results of the study also showed that the diffusion coefficient decreases with increasing particle size for all types. At the same time, spheres demonstrated the highest diffusion coefficient at the same size compared to other geometries, while plates have the lowest values ​​of this indicator. Analysis of the trajectories of particle motion in space using the GROMACS software allowed us to assess the influence of geometry on particle mobility. It was found that spheres exhibit the largest displacement amplitude, which indicates their high mobility and chaotic nature of the motion. Ellipsoids have a more stable motion with smaller displacements, which is associated with their geometric anisotropy. Plates, due to the large resistance of the environment, have the smallest displacements, which indicates limited mobility. It should be noted that the obtained research results open up opportunities for a deeper understanding of interactions in complex multicomponent systems and can be useful for further research in various fields. It is also worth noting that the comparison of different types of particles with different geometries and their influence on diffusion processes allowed us to obtain valuable information for improving models and practical applications in relevant fields of science and technology.

Abstract: The study of pedestrian dynamics, both individually and in groups, has been a highly active field for the last few decades. Dimensionless numbers in fluid dynamics are used to characterize flow patterns, identify the dominant forces, and predict results. Here, we argue that these dimensionless numbers can be also relevant to obtaining basic features of pedestrian dynamics. In this study, pedestrians moving freely and in an environment with other pedestrians are analyzed using dimensionless numbers. The development of a comfortable walking speed, the range of velocities that characterize walking and running forms of human gait, and the impact of pedestrian density on pedestrian speed are all investigated. Another important feature studied is the self-organization of a group of individuals, which is a vital concept in understanding crowd dynamics. Crowd dynamics and the interactions with other pedestrians are also investigated.

Abstract: The evolution of the steel structure under thermocyclic action is considered. The possibility of increasing the complex of mechanical properties of steels after thermocyclic treatment is shown.

Abstract: In this paper, the structures of spatial self-organization of steels after thermos-cyclic exposure were studied, using the fractal formalism method. It is shown that the structures, observed after cyclic heat exposure, can be characterized by the presence of the invariance property of their structure at different scale levels.

Abstract: The occurrence of flow pattern can be predicted based on constructal law. Scale analysis is a method for deriving the essential information based on the basic principles of fluid flow and heat transfer. It provides order-of-magnitudes but also the form of the functions that describe the quantities understudy. In flow systems, patterns (configuration, design, architecture) arise from competition between competing trends, at least two modes of transport or locomotion: slow (diffusion, walk, etc.) and fast (streams, run, etc.). Optimal patterns mean the best flow access and the best balance between these trends. The study presented here follows from the scale analysis together with constructal and, is illustrated by examples from simple water heating to human locomotion.

Abstract: The self-organization of COOH-functionalized multiwall carbon nanotubes (MWCNTs) during droplet evaporation of their aqueous suspension in a constant uniform electric field (E) was investigated. It was established that the COOH-functionalization polarizes the MWCNTs in the transverse direction to their axis. Depending on their size, MWCNTs tended to agglomerate into three different stable structures in different drop regions. There were linear, fractal and cluster structures (LS, FS, and CS). Sizes of the FSs decreased as 1/Е, whereas the rate of their growth increased as Е². The single-walled carbon nanotubes (SWCNTs) were found inside the LSs and CSs. The chiral indices of the SWCNTs were determined, corresponding to metallic and semiconducting conductivities. An analysis showed that as a result of coagulation and amassment of the carbon nanotubes (CNTs) near electrodes, there were formed conductive regions. When the concentration of MWCNTs reached some value in part nearest to an electrode, this part became conductive. The positive and negative electrodes, formed now by MWCNTs, shifted towards each other. The observed effects show that considered self-organization is controllable by the electric field.

Abstract: The system architecture for self-organizing smart home ecosystems must fulfill the standard requirements of measuring home conditions, processing instrumented data, and monitoring home appliances as well as providing self-configurations mechanisms for the sensors and actors forming the ecosystem. The communication framework should allow devices to discover counterpart devices, discover the services they offers, invoke these services when needed and get notifications about the state changes of their cooperation partners. Our approach takes advantages of the communication framework OPC UA, since it provided a set of prebuild services, which can be adapted to our needs. The following lines describe the OPC UA communication framework first and describe the architecture of our communication model secondly.

Abstract: The purpose of this study was to evaluate the TiO₂ nanotubes growth and the variation in its diameter to improve the surface properties of Ti-7.5Mo to use for biomedical applications. For the nanotubes TiO₂ growth, the samples were anodized in glycerol and ammonium fluoride and divided according to the anodizing potential at 5V to 10V and 24 hour time. The surfaces were examined by scanning electron microscope (SEM), X-ray analysis (XRD) and contact angle measurements. The average tube diameter, ranging in size from 13 to 23 nm, was found to increase with increasing anodizing voltage. It was also observed a decrease in contact angle in accordance with the increase in the anodizing potential. The X-ray analysis showed the presence of anatase phase in samples whose potential was 10V and this condition represents a simple surface treatment for Ti-7.5Mo alloy that has high potential for biomedical applications.

Abstract: The paper presents the study of the effect of hydrogenation on the mechanical properties of commercially pure titanium. It has been found that the localized deformation zones occurring in the plastically deforming Ti samples are stationary dissipative structures. The kinetics of dissipative structure evolution was studied. The hydrogenation treatment is found to enhance a tendency to strain localization in as-treated material, which affects significantly material strength properties.