Search results for " diagram"
showing 10 items of 722 documents
Zvaigžņotā Debess: 2010/11, Ziema (210)
2010
Contents: “ZVAIGŅOTĀ DEBESS” FORTY YEARS AGO: Bursting Stars. J. Francman (abridged). Geodesists Help Renew the Spire of St. Peter’s Church. J. Klētnieks (abridged). DEVELOPMENTS in SCIENCE: The Solar Neutrino Problem. O. Smirnova. NEWS: At Last the Planet at the Star β Pictoris Is Imaged. A. Alksnis, Z. Alksne. SPACE RESEARCH and EXPLORATION: The Trail of an Asteroid Reveals a Recent Collision. A. Alksnis. INTERNATIONAL YEAR of ASTRONOMY 2009: International Year of Astronomy 2009 in Philately. The Rest of the World except Series EUROPA (concluded). J. Limansky. ACADEMIC STAFF of the UNIVERSITY of LATVIA: Assistant Professor in Physics Ojārs Šmits (24.04.1930.-14.03.1993.) of the Latvian Un…
A model for the γN → ππN reaction
1995
We have studied the γN→ππN reaction using a model which includes N, Δ(1232), N*(1440) and N*(1520) intermediate baryonic states and the ρ-meson as intermediate ππ resonance. The model reproduces fairly well experimental cross sections below E γ = 800 MeV and invariant-mass distributions even at higher energies. One of the interesting findings of the study is that the γ N →N*(1520) → Δπ process is very important and interferes strongly with the dominant Δ-Kroll-Ruderman term to produce the experimental peak of the cross section.
A comparison of deontic matrices, maps and activity diagrams for the construction of situational methods
2007
Several approaches have been proposed to support situational method engineering (SME), each of them providing different techniques and using different basic concepts. In this work, we propose a framework for comparing SME approaches based on a generic SME process model. Three approaches are presented and compared by using this framework.
Ab Initio Study of BiFeO3: Thermodynamic Stability Conditions
2015
BiFeO3 is investigated intensively, mainly as a multiferroic material. In this paper, the state-of-the-art ab initio hybrid functional approach with atomic basis sets was employed for a study of the stability range of BiFeO3 with respect to its decomposition into binary oxides and elementary metals, as a function of temperature and oxygen partial pressure. The calculated atomic and electronic structure of BiFeO3 was compared with previous LDA+U calculations using plane-wave basis sets. Based on performed calculations, the phase diagram was constructed, which allows us to predict the stability region of stoichiometric BiFeO3.
Double precision errors in the logistic map: statistical study and dynamical interpretation.
2007
The nature of the round-off errors that occur in the usual double precision computation of the logistic map is studied in detail. Different iterative regimes from the whole panoply of behaviors exhibited in the bifurcation diagram are examined, histograms of errors in trajectories given, and for the case of fully developed chaos an explicit formula is found. It is shown that the statistics of the largest double precision error as a function of the map parameter is characterized by jumps whose location is determined by certain boundary crossings in the bifurcation diagram. Both jumps and locations seem to present geometric convergence characterized by the two first Feigenbaum constants. Even…
Adaptive Fuzzy Control of a Process with Bifurcations
2002
Several fuzzy controllers with different structures have been considered for the control of systems with bifurcation. A mixed feedforward-feedback structure with some additional adaptation mechanisms have been checked by simulation in the control of a non-linear process constituted by a bubble column in which a slow kinetics auto-catalytic reaction takes place. Simulation results show the validity of some of the proposed controllers in avoiding the system reaching bifurcation and instability conditions.
Thermodynamic study on phase equilibrium of epoxy resin/thermoplastic blends
2008
Abstract The experimental phase diagrams (cloud point curves) of three series of epoxy/thermoplastic blends, namely, epoxy/polystyrene (PS), epoxy/poly(ether sulfone) (PES), and epoxy/poly(ether imide) (PEI) as a function of molar mass and composition have been analysed from a thermodynamic point of view. A model based on the Flory–Huggins lattice theory considering the concentration dependence of the interaction parameter as predicted by Koningsveld was employed to determine the equilibrium compositions, and concentration and temperature dependent interaction parameters. Binodal, spinodal, and critical point data have been computed and show good agreement with experimental data.
Liquid-vapour phase behaviour of a symmetrical binary fluid mixture
1998
Using Monte-Carlo simulation and mean field calculations, we study the liquid-vapour phase diagram of a square well binary fluid mixture as a function of a parameter $\delta$ measuring the relative strength of interactions between particles of dissimilar and similar species. The results reveal a rich variety of liquid-vapour coexistence behaviour as $\delta$ is tuned. Specifically, we uncover critical end point behaviour, a triple point involving a vapour and two liquids of different density, and tricritical behaviour. For a certain range of $\delta$, the mean field calculations also predict a `hidden' (metastable) liquid-vapour binodal.
Calculation of phase diagrams not requiring the derivatives of the Gibbs energy demonstrated for a mixture of two homopolymers with the corresponding…
1995
A method is presented which allows the calculation of phase diagrams (spinodal, binodal and tie lines) on the basis of the Gibbs energy of mixing ΔG. No derivatives of ΔG with respect to the composition variables are required. This method is particularly useful in cases where the composition dependence of ΔG is very complex and no analytical representation of the derivatives can be given. The method is applied to a ternary mixture of two homopolymers with a copolymer consisting of the same monomers. The sequence distribution of the copolymer is kept constant between random and purely alternating, and phase diagrams are calculated for different chemical compositions of the copolymer. The com…
Calculation of miscibility behavior of multinary polymer blends
1996
A method for the calculation of phase diagrams (tie lines and binodal, spinodal, critical points and their stability) based exclusively on the Gibbs energy of mixing, δG, is presented which does not require the calculation of the derivatives with respect to the composition. The method is demonstrated for ternary mixtures of two homopolymers and the corresponding copolymer, and for quaternary and quinternary blends of five polymers exhibiting a closed miscibility gap. The advantages of the presented method become most obvious in the mathematical description of measured phase diagrams, where complex composition dependencies of the interaction parameter are observed.