Convection in the Rayleigh-Bénard Flow with all Fluid Properties Variable

In the present paper,the effect of variable fluid properties(density,viscosity,thermal conductivity and specific heat) on the convection in the classical Rayleigh-Bénard problem is investigated.The investigation concerns water,air,and engine oil by taking into account the variation of fluid properties with temperature.The results are obtained by numerically solving the governing equations,using the SIMPLE algorithm and covering large temperature differences.It is found that the critical Rayleigh number incr...     

Die Ausbildung der Wöhlerkurve eines niedriggekohlten Stahles bei Zug-Druck-Wechselbeanspruchung unter Berücksichtigung von Verfestigungs- und Entfestigungsvorgängen

Dauerschwingversuche (Aufnahme von Wöhlerkurven) und Zugversuche bei Raumtemperatur und tiefen Temperaturen, Aufnahme von mechanischen Hystereseschleifen, Messung von Dämpfung und Elastizitätsmodul im kHz-Bereich sowie elektronenoptische Untersuchungen an unterschiedlich vorbehandelten Proben eines unlegierten Baustahles mit 0,10% C zur Erforschung des Einflusses von Verfestigungsvorgängen infolge Verformungsalterung und Entfestigungsvorgängen infolge Vorverformung auf das Werkstoffverhalten unter elastisch-plastischer Zug-Druck-Wechselbeanspruchung.     

Zusammenhang zwischen der im instrumentierten Kerbschlagbiegeversuch ermittelten Bruchverformungsarbeit und der dynamischen Rißzähigkeit hochfester Stähle in Abhängigkeit von Temperatur und Kerbschärfe

An den Stählen St 52-3 und 35 NiCrMoV 12 5 wurden im instrumentierten Kerbschlagbiegeversuch bei einer Schlaggeschwindigkeit von 5 m/s die Bruchverformungsarbeit und die dynamische Rißzähigkeit bei unterschiedlicher Kerbschärfe und Prüftemperatur bestimmt. Es wurden die Einflüsse aufgezeigt, die bei der Bestimmung der wahren Bruchverformungsarbeit E_d gegenüber dem beim Kerbschlagbiegeversuch aufgenommenen Arbeitsverbrauch a_K berücksichtigt werden müssen. Die Versuchsergebnisse wurden verglichen und diskutiert, wobei auch die Gültigkeit einer Modellvorstellung von A. S. Tetelman zur Bestimmung der Rißzähigkeit an endlich gekerbten Proben überprüft wird.     

Recommendations of RILEM TC 127-MS: Tests for masonry materials and structures

RILEM Technical CommitteesRILEM TC 127-MS: Non Destructive Tests for Masonry Materials and Structures

Recommendations of RILEM TC 127-MS: Tests for masonry materials and structures     

FTIR spectroscopic study of some bismuth germanate glasses containing gadolinium ions

Since infrared spectroscopy and density are advantageous tools for the investigations of glasses, we have used them to obtain information concerning the local structure of xGd₂O₃·(100 − x)[4Bi₂O₃·GeO₂] glass system, with 0 ≤ x ≤ 30 mol%. Gd₂O₃ play the network modifier role in the studied glasses and determines, by progressive addition, the increase of structural volume difference between the hypothetical crystalline compounds and the quenched samples. FTIR spectroscopy data show that the glass structure consists on the BiO₆, GeO₄ and GeO₆ structural units, and the conversion among these units mainly depends on the Gd₂O₃ content.     

Synthesis of BaTiO3 by soft chemistry routes

In this paper we report a comparison concerning the properties of BaTiO₃ (BTO) ceramics obtained by two soft chemical routes, modified Pechini method and thermal decomposition of oxalate-based precursor. XRD data show the formation of single phase BaTiO₃ with tetragonal symmetry when the polymeric citrate-based precursor was annealed at 850 °C, 2 h. In the case of oxalate based-precursor, longer thermal treatment is required to obtain BaTiO₃ free of any secondary phases. For BaTiO₃ powders prepared by modified Pechini method, TEM and SEM investigations revealed the obtaining of uniformly sized particles forming spherical agglomerates inside large, non-uniform and partially sintered aggregates. The powders synthesized via oxalate route show particles of various sizes, with the same tendency of spherical agglomerates formation, but unlike the modified Pechini synthesis, more uniform and smaller aggregates with well-defined hexagonal-like shape were noticed. The relative permittivity values of 6,478 and 5,088 at Curie temperatures of 127 and 130 °C and low dielectric losses (tan δ?=?0.012) at room temperature were obtained for ceramic samples synthesized via Pechini method and oxalate route, respectively.     

Cancer Stem Cells: Biological Functions and Therapeutically Targeting

Almost all tumors are composed of a heterogeneous cell population, making them difficult to treat. A small cancer stem cell population with a low proliferation rate and a high tumorigenic potential is thought to be responsible for cancer development, metastasis and resistance to therapy. Stem cells were reported to be involved in both normal development and carcinogenesis, some molecular mechanisms being common in both processes. No less controversial, stem cells are considered to be important in treatment of malignant diseases both as targets and drug carriers. The efforts to understand the role of different signalling in cancer stem cells requires in depth knowledge about the mechanisms that control their self-renewal, differentiation and malignant potential. The aim of this paper is to discuss insights into cancer stem cells historical background and to provide a brief review of the new therapeutic strategies for targeting cancer stem cells.     

Towards a neighborhood simplification of tile systems: From Moore to quasi-linear dependencies

Self-assembly is the process by which objects aggregate independently and form complex structures. One of the theoretical frameworks in which the process of self-assembly can be embedded and formally studied is that of tile systems. A Wang tile is a square unit, with glues on its edges, attaching to other tiles which have matching glues, and forming larger and larger structures. In this paper we concentrate over two basic, but essential, self-assembling structures done by Wang tiles. The first one, called ribbon, is a non-self-crossing wire-like structure, in which successive tiles are adjacent along an edge, and where tiles are glued to their predecessor and successor by use of matching glues. The second one, called zipper, is a similar contiguous structure, only that here, all touching tiles must have matching glues on their abutting edges, independently of their position in the structure. In case of Wang tiles, it has been shown that these two structures are equivalent. Here we generalize this result for the case when the tiles have eight glues, four on their edges and four on their corners. Thus we show that an eight neighborhood dependency, namely the Moore neighborhood, can be simulated by a quasi-linear dependency.     

Utility assessment in automated driving for cooperative human–machine systems

Cognition, Technology & Work - Currently, car manufacturers, suppliers, and IT companies are surpassing each other with ambitious plans regarding their driving automation technology. However,...