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1

An impact of fiberglass fabric reinforcement on shelves made from particleboard

Szymska Anna, Beer Piotr

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2020

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No. 110

41--47

EN

An impact of fiberglass fabric reinforcement on shelves made from particleboard. The research used two variants of shelves reinforcement: reinforcement by gluing fibreglass cloth on particleboard and reinforcement by gluing pre-tensioned fibreglass cloth. The results obtained for reinforced shelves were compared to the results obtained for non-reinforced shelves. The characteristics of particleboard and existing on the global market ways to reinforce furniture shelves are presented in the initial chapters. Further chapters contain the methodology and the results of fatigue tests, shelf stiffness tests and modulus of elasticity tests. Based on the test results, it was found that the cloth reinforcement of particleboard furniture shelves using fiberglass with and without pre-tension results in the strength of the shelves by 15–40%. Also, reinforced shelves deflect less than the shelves made of unreinforced chipboard.

PL

Wpływ wzmocnienia tkaniną z włókna szklanego na półki z płyty wiórowej. W badaniach wykorzystano dwa warianty wzmocnienia półek: wzmocnienie poprzez podklejenie płyty wiórowej tkaniną z włókna szklanego oraz wzmocnienie poprzez podklejenie płyty wstępnie naprężoną tkaniną z włókna szklanego. Wyniki uzyskane dla półek wzmocnionych zostały porównane do wyników uzyskanych dla półek niewzmocnionych. W początkowych rozdziałach pracy przybliżono charakterystykę płyt wiórowych oraz istniejących na rynku sposobów na wzmacnianie półek meblowych. Dalsze rozdziały zawierają metodykę oraz wyniki badań takich jak badania zmęczeniowe, sztywność półek oraz badanie modułu sprężystości. Na podstawie przeprowadzonych badań stwierdzono, że wzmocnienie półek meblarskich wykonanych z płyty wiórowej tkaniną z włókna szklanego, bez i ze wstępnym naprężeniem, skutkuje wzmocnieniem płyt w granicach 15-40%. Również półki wzmocnione ulegają ugięciu w mniejszym stopniu niż półki z płyty wiórowej niewzmocnionej.

2

Edge waves over a shelf

Dolai P., Dolai D. P.

International Journal of Applied Mechanics and Engineering

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2019

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Vol. 24, no. 2

453--460

EN

The problem considered in this paper is the derivation of properties of edge waves travelling along a submerged horizontal shelf. The problem is formulated within the framework of the linearized theory of water waves and Havelock expansions of water wave potentials are used in the mathematical analysis to obtain the dispersion relation for edge waves in terms of an integral. Appropriate multi-term Galerkin approximations involving ultra spherical Gegenbauer polynomials are utilized to obtain a very accurate numerical estimate for the integral and hence to derive the properties of edge waves over a shelf. The numerical results are illustrated in a table and curves are presented showing the variation of frequency of the edge waves with the width of the shelf.

3

Facies architecture of the Cambrian succession at the western margin of Baltica in the Podlasie region (E Poland)

Wendorff Marek

Annales Societatis Geologorum Poloniae

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2019

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Vol. 89, No. 4

453--469

EN

Sedimentary features of the Cambrian-age succession transected in seven borehole cores sited in the Podlasie region document vertical and lateral variations of shallow-marine sedimentary facies, deposited at the rifted western margin of the Baltica Palaeocontinent. The boreholes are distributed along two lines of cross-section (E–W and NE–SW) running roughly perpendicular to the margin of the palaeocontinent. The easternmost borehole represents a proximal setting located on a relatively stable, shallow basement in the east; the remaining boreholes document conditions of deposition in the subsiding shallow-marine basin, extending towards the SW. Fourteen sedimentary facies defined on the basis of their lithological and sedimentary features are interpreted in terms of the sedimentary environments they represent. Strata deposited upon the stable craton in the east document a stratigraphically condensed succession of proximal facies, 240 m thick, whereas a sequence three times thicker is positioned distally, 170 km to the west. Facies associations in the proximal section represent the lower to upper shoreface in the lower part of the section and evolve upwards to the intermediate shoreface. Facies complexes in the remaining, intermediate and distal areas form a symmetrical megasequence, composed of a positive (i.e., fining-upwards – FU) transgressive sequence, overlain by a negative (coarsening-upwards – CU) regressive sequence. The vertical arrangement of the sedimentary subenvironments during the transgression indicates a tidally influenced shoreline followed by oscillations between the swash zone, the upper, intermediate and lower shoreface, and the offshore. The symmetry of the megasequences and the rhythmic pattern of the component facies complexes indicate that the intensity of supply in the terrigenous material and the efficiency of its reworking and redistribution within the basin were similar during the transgression and the regression. The facies types and variations within the basal part of the succession reflect syndepositional movements of tectonic blocks parallel to the rifted basin margin. Differences in total thickness and facies associations between the two lines of cross-section approximately perpendicular to the basin margin indicate that sedimentation was also influenced by a synsedimentary hinge fault, extending in a WSW–ENE direction.

4

Facies architecture of the Cambrian deposits of the Baltica shelf in the Lublin Basin, SE Poland

Stadnik Renata, Bębenek Sławomir, Waśkowska Anna

Annales Societatis Geologorum Poloniae

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2019

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Vol. 89, No. 2

105--120

EN

In the Cambrian, the Lublin Basin was a shallow-water area, located on the western edge of the Baltica palaeocontinent. The Cambrian sedimentary sequence, forming the lower part of the sedimentary cover of the North European Platform, is lithologically diversified and reflects dynamic variation in depositional environment. This paper presents the distribution of palaeofacies and sedimentary environments in the early Lublin Basin, including changes in their lateral extent during its evolution in the Cambrian. In order to evaluate the facies architecture of the Lublin Basin, a sedimentological analysis was carried out. On the basis of the detailed logging of drill cores, lithofacies made up of conglomerates, sandstones, mudstones and heterolithic deposits were distinguished; 16 lower-rank sublithofacies were identified. Their specific assemblages are indicative of shelf-type lithofacies associations, i.e. (1) tidal flat with muddy, mixed and sandy tidal plain sublithofacies including subtidal channels; (2) barrier-lagoon; (3) shoreface with lower, middle and upper shoreface subassociations; and (4) offshore with upper and lower offshore subassociations, including sandy tidal ridges. During the early Cambrian, the lateral variability and environmental succession indicate a transgressive, long-term trend and the migration of a lagoonal environment across wide tidal plains and the shoreface up to an offshore environment. The Lublin Basin reached its greatest lateral extent and maximum depth in the upper lower Cambrian. Next, an opposite trend began and during the middle Cambrian a regression cycle is recorded in successive changes in sedimentary environments that reflect a progressive shallowing. Multiple changes in adjacent environments indicate repeated and cyclical, lower-rank ingressions.

5

First find of biogenic activity in the Palaeoproterozoic of the Singhbhum craton (E India)

Loon A. J., Mazumder R.

Geologos

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2013

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Vol. 19, No. 3

185--192

EN

The Palaeoproterozoic succession of the Singhbhum craton in E. India was hitherto considered as almost entirely siliciclastic and partly volcanogenic. Here we describe, from the fine-grained, tidally influenced shale facies of the Palaeoproterozoic Chaibasa Formation (2.1-1.6 Ga), a fine, originally more or less horizontal, wavy to strongly undulating (later locally deformed) lamination. Investigation of these laminae shows that they must be ascribed to the accumulation of fine particles on microbial mats that covered a sandy substrate. The structures must therefore be considered as stromatolites, features that are accepted as proof of the presence of micro-organisms, in this case most probably cyanobacteria. The interpretation of biogenic activity is supported by microscopic analysis. It is the first description of traces left by biogenic activity that took place in the Palaeoproterozoic of the Singhbhum craton.