Consistent multiphase-field theory for interface driven multidomain dynamics

We present a new multiphase-field theory for describing pattern formation in multi-domain and/or multi-component systems. The construction of the free energy functional and the dynamic equations is based on criteria that ensure mathematical and physical consistency. We first analyze previous multiphase-field theories, and identify their advantageous and disadvantageous features. On the basis of this analysis, we introduce a new way of constructing the free energy surface, and derive a generalized multiphase description for arbitrary number of phases (or domains). The presented approach retains the variational formalism; reduces (or extends) naturally to lower (or higher) number of fields on the level of both the free energy functional and the dynamic equations; enables the use of arbitrary pairwise equilibrium interfacial properties; penalizes multiple junctions increasingly with the number of phases; ensures non-negative entropy production, and the convergence of the dynamic solutions to the equilibrium solutions; and avoids the appearance of spurious phases on binary interfaces. The new approach is tested for multi-component phase separation and grain coarsening

God and the physical reality

We seek value. We seep positive value what is presented in the physical reality. There is a common expression of value in the Universe. Mathematics. There is a reason why we realize value. There is a reason why 1*0=

Hydrodynamic theory of freezing: Nucleation and polycrystalline growth

Structural aspects of crystal nucleation in undercooled liquids are explored using a nonlinear hydrodynamic theory of crystallization proposed recently [G. I. Toth et al., J. Phys.: Condens. Matter 26, 055001 (2014)], which is based on combining fluctuating hydrodynamics with the phase-field crystal theory. We show that in this hydrodynamic approach not only homogeneous and heterogeneous nucleation processes are accessible, but also growth front nucleation, which leads to the formation of new (differently oriented) grains at the solid-liquid front in highly undercooled systems. Formation of dislocations at the solid-liquid interface and interference of density waves ahead of the crystallization front are responsible for the appearance of the new orientations at the growth front that lead to spherulite-like nanostructures

Crystallization: colloidal suspense

According to classical nucleation theory, a crystal grows from a small nucleus that already bears the symmetry of its end phase—but experiments with colloids now reveal that, from an amorphous precursor, crystallites with different structures can develop

INVESTIGATION ON THE SURFACE QUALITY OF BÖHLER S290 POWDER METALLURGICAL TOOL STEEL AFTER WEDM MACHINING

Nowadays, there is a growing demand for fast, accurate and precise tool manufacturing. At the same time, the requirements for the quality of tool steel materials have also increased. Increasingly, tools are being made from high alloyed, highest purity, segregation free, homogenous and high hardness materials. These materials are difficult to machine with conventional technology. For this problem a solution could be the electrical discharge machining technology (EDM). During the EDM process an electrical discharge occurs between an anode and a cathode in a dielectric medium [1]. The EDM process is characterized by high heat, that cause structural changes on the surface of the machined materials. In EDM process the surface of the machined material is eroded by melting and evaporation due to large quantity of heat [2]. This paper presents a study of the wire EDM machining surface of S290 PM HSS materials with different parameters performed by multiple cutting. The aim of this investigation was to find the optimal parameters and trim cuts number for the efficient production of the tools from S290 HSS PM materials with the required surface qualit

Phase-field modeling of eutectic structures on the nanoscale: the effect of anisotropy

A simple phase-field model is used to address anisotropic eutectic freezing on the nanoscale in two (2D) and three dimensions (3D). Comparing parameter-free simulations with experiments, it is demonstrated that the employed model can be made quantitative for Ag-Cu. Next, we explore the effect of material properties, and the conditions of freezing on the eutectic pattern. We find that the anisotropies of kinetic coefficient and the interfacial free energies (solid-liquid and solid-solid), the crystal misorientation relative to pulling, the lateral temperature gradient, play essential roles in determining the eutectic pattern. Finally, we explore eutectic morphologies, which form when one of the solid phases are faceted, and investigate cases, in which the kinetic anisotropy for the two solid phases are drastically different

Relationship Marketing on the Market of Advertising Agencies

In today´s competitive business environment, to achieve and retain business success, it is essential to devote sufficient attention to building business relationships. Recognition of factors, influencing the success of business relationships, has long been a topic of professionals and those who are interested in this field. When getting in touch with a customer, the company aims to establish a strong relationship with the customer, to win indifferent customers and to create customer loyalty. Based on the factors above, we found it important to determine the perception of the importance of factors which determine contacting customers the most from the customers´ point of view in the market of advertising agencies. Regarding further successful cooperation, it is essential to address customers with a proper campaign. Therefore, this paper aims to identify emerging customer groups when building relationships in the advertising market, thus facilitating the realization of personalized campaigns

Rectus sheath haematoma following exercise testing: a case report

<p>Abstract</p> <p>Introduction</p> <p>Exercise testing is a safe diagnostic procedure which is widely used in the evaluation of patients suspected of having coronary heart disease or for the assessment of the prognosis in patients with established disease. Its complications are mainly cardiac disorders. Here, we report a rectus sheath haematoma as a complication of this procedure in a patient with acute coronary syndrome. To our knowledge, this is the first case report of rectus sheath haematoma in association with exercise testing.</p> <p>Case presentation</p> <p>A 72-year-old Caucasian woman was admitted for acute coronary syndrome. She received conservative treatment including low molecular weight heparin and anti-platelet agents. On the fifth day of her hospital stay, she underwent an exercise test, where no ischaemic response occurred. Several hours later, she experienced pain in the left side of her abdomen. Subsequent investigations revealed a rectus sheath haematoma. The patient underwent surgical haematoma evacuation. A few days later, re-operation was performed for recurrent bleeding in the abdominal wall. The patient had several characteristics known to increase the risk of bleeding during treatment for acute coronary syndrome.</p> <p>Conclusion</p> <p>Awareness of this possible consequence of exercise testing is important for preventing and treating it correctly. For prevention, an assessment of the bleeding risk of the individual patient is necessary before the test, and excessive anticoagulation must be avoided.</p