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391.
392.
The peculiarities of cross-correlation between two secondary precursors - radon and magnetic field variations, induced by tectonic activity
Vitalii Danilovich Rusov, V. Yu. Maksymchuk, Radomir Ilić, V.M. Pavlovych, V. G. Bakhmutov, D. N. Saranuk, V.M. Vaschenko, Jure Skvarč, Lucija Hanžič, S. I. Kosenko, 2006, drugi članki ali sestavki

Opis: A model of precursor manifestation mechanisms, stimulated by tectonic activityand some peculiarities of observer strategy, whose main task is the effective measurement of precursors in the spatial area of their occurrence on the Earth's daylight, are considered. In particular, the applicability of Dobrovolsky's approximation is analyzed, when an unperturbed medium (characterized by the simple shear state) and the area of tectonic activity (local inhomogeneity caused by the change only of shear modulus) are linearly elastic, and perturbation, in particular, surface displacement is calculated as a difference of the solutions of two independent static problems of the theory of elasticity with the same boundary condition on the surface. Within the framework of this approximation a formula for the spatial distribution (offirst component) of magnetic field variations caused by piezomagnetic effect in the case of perturbed regular medium, which is in simple shear state is derived. Cogent arguments in favor of linear dependence between the radon spatial distribution and conditional deformation are obtained. Changes in magnetic field strength and radon concentrations were measured along a tectonomagnetic profile of the total length of 11 km in the surroundings of the "Academician Vernadsky" Station on the Antarctic Peninsula (W 64 16', S 6515'). Results showed a positive correlation between the annual surface radonconcentration and annual changes of magnetic field relative to a base point, and also the good coincidence with theoretical calculation.
Ključne besede: geophysics, tectonic activity, radon, precursors
Objavljeno: 31.05.2012; Ogledov: 798; Prenosov: 6
URL Celotno besedilo (0,00 KB)

393.
Evaluation of Green`s function for vertical point-load excitation applied to the surface of a semi-infinite elastic medium
Andrej Štrukelj, Tomaž Pliberšek, Andrej Umek, 2006, izvirni znanstveni članek

Opis: The topic of this paper is to show that the integrals of infinite extent representing the surface displacements of a layered half-space loaded by a harmonic, vertical point load can be reduced to integrals with finite integration range. The displacements are first expressed through wave potentials and the Hankel integral transform in the radial coordinate is applied to the governing equations and boundary conditions, leading to the solutions in the transformed domain. After the application of the inverse Hankel transform it is shown that the inversion integrands are symmetric/antimetric in the transformation parameter and that this characteristic is preserved for any number of layers. Based on this fact the infinite inversion integrals are reduced to integrals with finite range by choosing the suitable representation of the Bessel function and use of the fundamental rules of contour integration, permitting simpler analytical or numerical evaluation. A numerical example is presented and the results are compared to those obtained by the CLASSI program.
Ključne besede: civil engineering, soil mechanics, Green`s function, layered half-space, vertical point load
Objavljeno: 31.05.2012; Ogledov: 1161; Prenosov: 5
URL Celotno besedilo (0,00 KB)

394.
Analiza vpliva prometnega toka pešcev na prepustno zmožnost krožišča z uporabo diskretnih simulacij
Tomaž Tollazzi, Tone Lerher, Matjaž Šraml, 2006, izvirni znanstveni članek

Opis: Podobno kakor v običajnih nesemaforiziranih kriziščih lahko tudi pri krožiščih, v posebnih prometnih razmerah, prihaja do bistvenega zmanjšanja prepustnosti. V takih primerih je značilno, da je prometni tok pescev in/ali kolesarjev pri prečkanju enega ali več krakov krozišča tako močan, da vpliva na polnjenje ali na praznjenje krozišča. Namen prispevka je ponazoriti, kako lahko uporaba diskretnih simulacij prispeva k odločitvi o izvedbi krožišča, oziroma ali bo krožišče primerno izpolnjevalo pogoj zmogljivosti ob pričakovanem prometnem toku pešcev in/ali kolesarjev. Predlagan je nov način obravnave problematike dimenzioniranja krožišč z vidika matematičnega modeliranja prometnih tokov z uporabo metode diskretnih simulacij, z upoštevanimi statistično ovrednotenimi vhodnimi podatki za prometni tok vozil in pešcev. Rezultati simulacij so uporabni pri določanju prepustnosti načrtovanih krozišč, ki bodo delovali v različnih prometnih okoliščinah. Predstavljen model izhaja iz sprejemljive časovne praznine v prometnem toku pešcev, ki jo uporabljajo motorna vozila za uvažanje in izvažanje iz krožišča, če upoštevamo, da imajo pešci prednost. Simulacijska analiza je preverjena na dejanskem primeru montažnega krožišča v Mariboru, na Koroški ulici, kjer so bile izvedene tudi potrebne meritve prometnega toka motornih vozil ter pešcev in kolesarjev. Postopek, prikazan v prispevku, predstavlja poleg znanstvenega postopka matematičnega modeliranja tudi praktično metodo za pomoč pri odločanju o smiselnosti izvedbe krožišča v primeru močnega toka pešcev in/ali kolesarjev.
Ključne besede: cestni promet, krožišča, prometni tokovi, analiza vplivov, simulacijski modeli
Objavljeno: 31.05.2012; Ogledov: 976; Prenosov: 22
URL Celotno besedilo (0,00 KB)

395.
396.
The impact of mineral composition on compressibility of saturated soils
Bojana Dolinar, 2006, izvirni znanstveni članek

Opis: This article analyses the impact of soils` mineral composition on their compressibility. Physical and chemical properties of minerals which influence the quantity of intergrain water in soils and, consequently, the compressibility of soils are established by considering the previous theoretical findings. Test results obtained on artificially prepared samples are used to determine the analytical relationship between the water content and stress state, depending on the mineralogical properties of the soils. A practical applicability of the established interdependence is verified on fiverandomly selected samples of natural soils. The selected approach to the analysis of the influence of soils composition on the water content at different stress states allows for the first time to establish generally validcriteria for determining such relationship.
Ključne besede: soil mechanics, clays, specific surface, compressibility, mineral composition
Objavljeno: 30.05.2012; Ogledov: 640; Prenosov: 5
URL Celotno besedilo (0,00 KB)

397.
On Euclidean algebra of hermitian operators on a quadratic Hilbert space
Rok Strašek, 2006, izvirni znanstveni članek

Opis: We solve the problem of finding the best possible constant of ultraprimeness for the special class of Euclidean algebra called algebra of hermitian operators on a quaternionic Hilbert space. More precisely, we prove that for algebra of hermitian operators, equipped with spectral norm, the best possibleconstant of ultraprimeness is 1/2.
Ključne besede: mathematics, Euclidean algebras, quaternionic Hilbert space, ultraprime algebras, Jacobson-McCrimmon operator, spectral norm
Objavljeno: 30.05.2012; Ogledov: 702; Prenosov: 5
URL Celotno besedilo (0,00 KB)

398.
Cost estimation, optimization and competitiveness of different composite floor systems
Uroš Klanšek, Stojan Kravanja, 2006, izvirni znanstveni članek

Opis: Part 2 presents the cost optimization, comparison and competitiveness between three different composite floor systems: composite beams produced from duo-symmetrical welded I sections, composite trusses formed from rolled channel sections and composite trusses made from cold formed hollow sections. In order to carry out a precise comparison between the mentioned composite systems, we applied the structural optimization method rather than classical structural analysis. The optimization was performed by the non-linear programming approach, NLP. The parametric optimization was made for simply supported beams of different spans, loads, steel costs (prices) and different hourly labour costs. An accurate cost objective function of the self-manufacturing material, power and labour costs, described in Part 1, we redefined for the optimization and subjected to the design, stress and deflection (in)equality constraints in order to satisfy the requirements of both the ultimate and the serviceability limit state. The composite structures were designed in accordance with Eurocode 4. The aim of the comparison was to define the spans and loads, at which each of the presented composite structures shows its advantages. Comparative diagrams, displayed at the end of the paper, can be usefully applied for choosing the optimal type of structure.
Objavljeno: 30.05.2012; Ogledov: 614; Prenosov: 10
URL Celotno besedilo (0,00 KB)

399.
Cost estimation, optimization and competitiveness of different composite floor systems
Uroš Klanšek, Stojan Kravanja, 2006, izvirni znanstveni članek

Opis: This paper presents self-manufacturing cost estimation, cost optimization and competitiveness of different composite floor systems: composite I beams, composite trusses produced from rolled channel sections and composite trusses made from cold formed hollow sections. Part 1 of this two-part series of papers presents the estimation of the self-manufacturing (direct production) costs for composite and steel structures. The self-manufacturing costs are proposed to be defined as the sum of the material, the power consumption and the labour costs. The material costs of the structural steel, concrete, reinforcement, the shear connectors, electrodes, the anti-corrosion, fire protection and top coat painting, the formwork floor-slab panels and gas consumption are presented in detail. The power consumption costs comprise costs of sawing the steel sections, edge grinding, drilling, welding, stud welding and vibrating the concrete. The labour costs (times) presented define the costs of metal cutting, edge grinding, preparation, assembling and tacking, welding, welding of shear connectors, steel surface preparation and protection, drilling, cutting, placing and connecting the reinforcement, concreting, consolidating and curing the concrete. New approximation functions are proposed for the calculation of some manufacturing times and material consumptions. As the discussed costs vary significantly around the world, the proposed cost expressions are given in the open form to be used for cost estimation in different economic conditions. A numerical example of the estimation of the self-manufacturing costs for a composite I beam floor system shows the suitability of the proposed approach. On the basis of the defined self-manufacturing costs, introduced in Part 1, the cost optimization and the competitiveness of different composite floor systems are discussed in Part 2.
Ključne besede: cost estimation, self-manufacturing costs, material costs, power consumption costs, labour costs, steel structures, composite structures, welded structures
Objavljeno: 30.05.2012; Ogledov: 990; Prenosov: 9
URL Celotno besedilo (0,00 KB)

400.
Tehnični vidiki varnosti v cestnem prometu : skripta za predavanja na študijskem programu Prometno inženirstvo VS (modul Cestni promet)
Stanko Laković, 2011, učbenik za višje in visoke šole

Opis:
Objavljeno: 29.02.2012; Ogledov: 1774; Prenosov: 311
URL Celotno besedilo (0,00 KB)
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