Energy transfer in isotropic turbulence at low Reynolds numbers

Detailed measurements were made of energy transfer among the scales of motion in incompressible turbulent fields at low Reynolds numbers generated by direct numerical simulation. It was observed that although the transfer resulted from triad interactions that were non-local in k space, the energy always transferred locally. The results are consistent with the notion of non-uniform advection of small weak eddies by larger and stronger ones, similar to transfer processes in the far dissipation range at high Reynolds numbers

The challenge of freedom in the Southeastern Europe. OSW Report, July 2015

Over the past few decades substantial progress has been achieved in the democratisation and modernisation of the countries of Southeastern Europe. The formal democratic institutions were introduced, a liberalisation of trade resulted in the reintegration of the region into the global economy and some of them successfully applied to join the EU and NATO. But the transformation process is far from over. In the past years the achievements of the political and economic transformation have been rolled back and the quality of governance has declined in many countries. To avoid a further deterioration of the situation in the region the new impulse for institutional transformation and a change of the development model are needed. This report is the outcome of a discussion held during the conference “The Freedom Challenge in Southeastern Europe – Implications for Poland”. This joint event was developed by the Centre for Eastern Studies and Ideas Lab – the President’s Expert Programme at the Chancellery of the President of the Republic of Poland. The chapters of the report reflect the main three subjects debated during the conference. In the first chapter Spasimir Domaradzki assesses the rule of law and its influence on the consolidation of democracy in the region. In the second chapter Marta Szpala focuses on economic development in Southeastern Europe. The third chapter is written by Adam Balcer and analyses the key instruments Russia is using to build influence in this region

Hard Sphere Dynamics for Normal and Granular Fluids

A fluid of N smooth, hard spheres is considered as a model for normal (elastic collisions) and granular (inelastic collisions) fluids. The potential energy is discontinuous for hard spheres so the pairwise forces are singular and the usual forms of Newtonian and Hamiltonian mechanics do not apply. Nevertheless, particle trajectories in the N particle phase space are well defined and the generators for these trajectories can be identified. The first part of this presentation is a review of the generators for the dynamics of observables and probability densities. The new results presented in the second part refer to applications of these generators to the Liouville dynamics for granular fluids. A set of eigenvalues and eigenfunctions of the generator for this Liouville dynamics is identified in a special "stationary representation". This provides a class of exact solutions to the Liouville equation that are closely related to hydrodynamics for granular fluids.Comment: Submitted for publication in the Proceedings of Workshop on Nonlinear Dynamics in Astronomy and Physics, eds. S. Gottesmann and J. R. Buchler (Annals of the New York Academy of Sciences, 2005

Large Eddy Simulation of Turbulent Channel Flows by the Rational LES Model

The rational large eddy simulation (RLES) model is applied to turbulent channel flows. This approximate deconvolution model is based on a rational (subdiagonal Pade') approximation of the Fourier transform of the Gaussian filter and is proposed as an alternative to the gradient (also known as the nonlinear or tensor-diffusivity) model. We used a spectral element code to perform large eddy simulations of incompressible channel flows at Reynolds numbers based on the friction velocity and the channel half-width Re{sub tau} = 180 and Re{sub tau} = 395. We compared the RLES model with the gradient model. The RLES results showed a clear improvement over those corresponding to the gradient model, comparing well with the fine direct numerical simulation. For comparison, we also present results corresponding to a classical subgrid-scale eddy-viscosity model such as the standard Smagorinsky model.Comment: 31 pages including 15 figure

Evaluation of the Mineral Concentration in Beef from Polish Native Cattle

The aim of the study was to determine the content of macrominerals and microminerals in the longissimus lumborum (LL) and semitendinosus (ST) muscles of young bulls of five breeds—Polish Red (PR), White-Backed (WB), Polish Black-and-White (PBW), Simmental (SIM) and Polish Holstein-Friesian (PHF). The meat of the Polish Holstein-Friesian bulls was found to contain significantly less K, Mg and Ca and more Mn than other breeds. The meat of the White-Backed bulls contained significantly (P < 0.01) more Ca and less Na than the meat of the Polish Red, Simmental and Polish Holstein-Friesian breeds. Moreover, the meat of White-Backed bulls showed a significantly (P < 0.01) higher level of Mn and Cu in comparison with other native breeds (Polish Red and Polish Black-and-White) and the Simmental breed. Similar content of macronutrients was found in the LL and ST muscles. However, in the case of micronutrients, the LL muscle contained significantly more Zn, Fe and Cu as well as Mn (P > 0.05)

Energy transfer in two-dimensional magnetohydrodynamic turbulence: formalism and numerical results

The basic entity of nonlinear interaction in Navier-Stokes and the Magnetohydrodynamic (MHD) equations is a wavenumber triad ({\bf k,p,q}) satisfying ${\bf k+p+q=0}$. The expression for the combined energy transfer from two of these wavenumbers to the third wavenumber is known. In this paper we introduce the idea of an effective energy transfer between a pair of modes by the mediation of the third mode, and find an expression for it. Then we apply this formalism to compute the energy transfer in the quasi-steady-state of two-dimensional MHD turbulence with large-scale kinetic forcing. The computation of energy fluxes and the energy transfer between different wavenumber shells is done using the data generated by the pseudo-spectral direct numerical simulation. The picture of energy flux that emerges is quite complex---there is a forward cascade of magnetic energy, an inverse cascade of kinetic energy, a flux of energy from the kinetic to the magnetic field, and a reverse flux which transfers the energy back to the kinetic from the magnetic. The energy transfer between different wavenumber shells is also complex---local and nonlocal transfers often possess opposing features, i.e., energy transfer between some wavenumber shells occurs from kinetic to magnetic, and between other wavenumber shells this transfer is reversed. The net transfer of energy is from kinetic to magnetic. The results obtained from the studies of flux and shell-to-shell energy transfer are consistent with each other.Comment: 27 pages REVTEX; 14 ps figure

Incompressible Turbulence as Nonlocal Field Theory

It is well known that incompressible turbulence is nonlocal in real space because sound speed is infinite in incompressible fluids. The equation in Fourier space indicates that it is nonlocal in Fourier space as well. Contrast this with Burgers equation which is local in real space. Note that the sound speed in Burgers equation is zero. In our presentation we will contrast these two equations using nonlocal field theory. Energy spectrum and renormalized parameters will be discussed.Comment: 7 pages; Talk presented in Conference on "Perspectives in Nonlinear Dynamics (PNLD 2004)" held in Chennai, 200

New high-pressure phase of HfTiO4 and ZrTiO4 ceramics

We studied the high-pressure effects on the crystalline structure of monoclinic HfTiO4 and ZrTiO4. We found that the compressibility of these ceramics is highly non-isotropic, being the b-axis the most compressible one. In addition, the a-axis is found to have a small and negative compressibility. At 2.7 GPa (10.7 GPa) we discovered the onset of an structural phase transition in HfTiO4 (ZrTiO4), coexisting the low- and high-pressure phases in a broad pressure range. The new high-pressure phase has a monoclinic structure which involves an increase in the Ti-O coordination and a collapse of the cell volume. The equation of state for the low-pressure phase is also determined.Comment: 16 pages, 5 figures, 26 references, Article in Pres

The Council of Europe’s Human Rights system after sixty years – Political evolution and continuance

"The sixtieth anniversary of the Council of Europe (hereinafter “CoE”) provides opportunity for reflection on the political developments in the field of human rights in Europe. The organization, which was established in order to promote such values as rule of law, human rights and democracy, created the most efficient mechanism of human rights protection worldwide. This regional system of human rights, being associated with the “West” during the Cold War era, today gathers forty seven member states. All of them, at least theoretically, comply with the highest standards of individual protection and recognize the authority of the European Court of Human Rights (hereinafter “ECtHR” or “the Court”)."(...

Religion and american foreign policy: Contesting the obvious

From introduction: "The role of religion in U.S. foreign policy is a very complex issue. Dependent on the personal attitude of the researcher, religion can play a major or secondary role in analyzing the process of shaping American behavior in international relations. This topic is extremely difficult for political scientists (and I daresay for other scholarly approaches as well) due to its inherently internal nature. It is easier to research and analyze open, accessible and, even if controversial, publicly discussed topics. However, this is not the case with religion. When asked to contribute to the volume on this topic the first feeling was confusion. Undoubtedly, there is religious inclination in the deeds and actions of the following American administrations, but does that mean that all the actions are guided by religious principles? Does it mean that the point of relevance is the divine principles of Christianity? Is the Decalogue the driving force of American foreign policy? Ultimately, how can we measure this topic? I will risk saying no to these questions."(...