Cylindrically Symmetric Inhomogeneous Universes with a Cloud of Strings

Cylindrically symmetric inhomogeneous string cosmological models are investigated in presence of string fluid as a source of matter. To get the three types of exact solutions of Einstein's field equations we assume $A = f(x)k(t)$, $B = g(x)\ell(t)$ and $C = h(x)\ell(t)$. Some physical and geometric aspects of the models are discussed.Comment: 9 page

A New Class of Inhomogeneous String Cosmological Models in General Relativity

A new class of solutions of Einstein field equations has been investigated for inhomogeneous cylindrically symmetric space-time with string source. To get the deterministic solution, it has been assumed that the expansion ($\theta$) in the model is proportional to the eigen value $\sigma^{1}_{1}$ of the shear tensor $\sigma^{i}_{j}$. Certain physical and geometric properties of the models are also discussed.Comment: 12 pages, no figure. Submitted to Astrophys. Space Sci. arXiv admin note: substantial text overlap with arXiv:0705.090

Bianchi Type V Viscous Fluid Cosmological Models in Presence of Decaying Vacuum Energy

Bianchi type V viscous fluid cosmological model for barotropic fluid distribution with varying cosmological term $\Lambda$ is investigated. We have examined a cosmological scenario proposing a variation law for Hubble parameter $H$ in the background of homogeneous, anisotropic Bianchi type V space-time. The model isotropizes asymptotically and the presence of shear viscosity accelerates the isotropization. The model describes a unified expansion history of the universe indicating initial decelerating expansion and late time accelerating phase. Cosmological consequences of the model are also discussed.Comment: 10 pages, 3 figure

Covariant baryon charge radii and magnetic moments in a chiral constituent quark model

The charge radii and magnetic moments of all the light and strange baryons are investigated within the framework of a constituent quark model based on Goldstone-boson-exchange dynamics. Following the point-form approach to relativistic quantum mechanics, the calculations are performed in a manifestly covariant manner. Relativistic (boost) effects have a sizeable influence on the results. The direct predictions of the constituent quark model are found to fall remarkably close to the available experimental data.Comment: 6 pages, 4 table

Observing Long Colour Flux Tubes in SU(2) Lattice Gauge Theory

We present results of a high statistics study of the chromo field distribution between static quarks in SU(2) gauge theory on lattices of volumes 16^4, 32^4, and 48^3*64, with physical extent ranging from 1.3 fm up to 2.7 fm at beta=2.5, beta=2.635, and beta=2.74. We establish string formation over physical distances as large as 2 fm. The results are tested against Michael's sum rules. A detailed investigation of the transverse action and energy flux tube profiles is provided. As a by-product, we obtain the static lattice potential in unpreceded accuracy.Comment: 66 pages, 29 figures, uuencoded latex file with epsfigures (450 K), supplementary full colour figures are available via ftp, CERN-TH.7413/94 (extended version

Some Bianchi Type III String Cosmological Models with Bulk Viscosity

We investigate the integrability of cosmic strings in Bianchi III space-time in presence of a bulk viscous fluid by applying a new technique. The behaviour of the model is reduced to the solution of a single second order nonlinear differential equation. We show that this equation admits an infinite family of solutions. Some physical consequences from these results are also discussed.Comment: 12 pages, no figure. To appear in Int. J. Theor. Phy

Contribution based multi-island competitive cooperative coevolution

Competition in cooperative coevolution (CC) has demonstrated success in solving global optimization problems. In a recent study, a multi-island competitive cooperative coevolution (MIC3) algorithm was introduced that featured competition and collaboration of several different problem decomposition strategies implemented as independent islands. It was shown that MIC3converges to high quality solutions without the need to find an optimal decomposition. MIC3splits the computational budget in terms of the number of function evaluations, equally amongst all the islands and evolves them in a round-robin fashion. This overlooks the difference in contributions of different islands towards improving the overall objective function value. Therefore, a considerable amount of function evaluations is wasted on the low-contributing islands as their problem decomposition strategies may not appeal to the problem at the given stage of the evolutionary process. This paper proposes contribution-based MIC3 algorithms (MIC4) that quantifies the contributions of each island and allocates the computational budget accordingly. The experimental analysis reveals that the proposed method outperforms its counterpart

Comportement d’un béton à hautes performances à base de laitier en milieu sulfatique

L'utilisation de béton à hautes performances (BHP) intégrant des ajouts cimentaires comme les cendres volantes, les fumées de silice ou le laitier hydraulique cimentaire a augmenté considérablement au cours des deux dernières décennies. Les ouvrages en BHP durent plus longtemps et entraînent des frais d'entretien moins élevés que ceux en béton ordinaire. De plus, le BHP utilise moins de ciment, ce qui diminue les émissions de CO2. Une plus vaste utilisation du béton à hautes performances intégrant des ajouts cimentaires pourrait donc entraîner des bénéfices tant environnementaux que financiers et construire des ouvrages plus durables. A l’état actuel, la recherche sur les bétons à hautes performances en Algérie est surtout axée sur leurs formulations en vue de produire des bétons de meilleures résistances et durables. Cependant, une composition optimale dépend de plusieurs paramètres, en particulier du choix des ingrédients. L'effet des ajouts cimentaires et leur finesse reste peu entrepris. C'est pourquoi nous nous proposons dans ce travail, de formuler des bétons à hautes performances avec et sans ajout cimentaire et de traiter l’influence du laitier de l’usine sidérurgique d’El-hadjar (Algérie), finement broyé et substitué à une partie de ciment, sur les caractéristiques physico-mécaniques des bétons élaborés.Mots clés : BHP - Laitier - Durabilité - Sulphate

Kemampuan Serapan Abu Tulang Kambing terhadap Variasi Konsentrasi Ion Sulfat

Calcium oxide was a major component in bone ash. This calcium oxide has relativelyopened structure, so it can be used as an adsorbent. Its adsorption ability on sulfate ionhas been analyzed in an solution. The analysis of sulfate ion was carried out usingSpectrophotometer UV-VIS by turbidimetry method. The results showed thatconcentration of bone ash affected to the adsorption of sulfate ion with optimumadsorption of 80.833% at 10 ppm of bone ash