Elastic, thermal expansion, plastic and rheological processes - theory and experiment

Rocks are important examples for solid materials where, in various engineering situations, elastic, thermal expansion, rheological/viscoelastic and plastic phenomena each may play a remarkable role. Nonequilibrium continuum thermodynamics provides a consistent way to describe all these aspects in a unified framework. This we present here in a formulation where the kinematic quantities allow arbitrary nonzero initial (e.g., in situ) stresses and such initial configurations which - as a consequence of thermal or remanent stresses - do not satisfy the kinematic compatibility condition. The various characteristic effects accounted by the obtained theory are illustrated via experimental results where loaded solid samples undergo elastic, thermal expansion and plastic deformation and exhibit rheological behaviour. From the experimental data, the rheological coefficients are determined, and the measured temperature changes are also explained by the theory.Comment: 15 pages, to appear in Period. Polytech. Civil En

Hydraulic Model Calibration and Performance Assessment of Pressure Managed Areas with Multiple Inlets

Pressure management is a widely adopted technique in the toolset of drinking water distribution system operators. It has multiple benefits, like reducing physical losses in pipe networks with excessive leakage, prolong the expected lifetime of the pipes and protecting home appliances from unacceptably high pressure. In some cases, even legislation compliance can be the motivation behind pressure management: It is mandatory to supply water at the customer’s connection between 1.5 and 6.0 bar in Hungary since 2011. Diaphragm pressure reducing valves are widespread in the drinking water distribution networks. Although, their sensitivity for gas pocket accumulation in the valve house makes hydraulic calibration of these pressure managed areas a challenging task for hydraulic modelers and network operators. This is especially true when more than one inlet is used to supply the same area in order to increase resilience and flow capacity.This paper investigates the hydraulic properties of pressure reduced areas with multiple inlet points. Model calibration using a single valve and minor loss was found insufficient because the additional pressure loss referenced to the pressure setting has a non-quadratic relationship with flow-rate on the discharge side under real-life circumstances. This phenomenon can be handled by using a PRV (pressure reducing valve) + GPV (general purpose valve) in series

On pairwise comparison matrices that can be made consistent by the modification of a few elements

Pairwise comparison matrices are often used in Multi-attribute Decision Making for weighting the attributes or for the evaluation of the alternatives with respect to a criteria. Matrices provided by the decision makers are rarely consistent and it is important to index the degree of inconsistency. In the paper, the minimal number of matrix elements by the modification of which the pairwise comparison matrix can be made consistent is examined. From practical point of view, the modification of 1, 2, or, for larger matrices, 3 elements seems to be relevant. These cases are characterized by using the graph representation of the matrices. Empirical examples illustrate that pairwise comparison matrices that can be made consistent by the modification of a few elements are present in the applications

Host alarm calls attract the unwanted attention of the brood parasitic common cuckoo

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Fluorination of some functionalized cycloalkenes through epoxidation and oxirane opening with Deoxofluor or XtalFluor-E

A convenient, simple synthetic method is described for the synthesis of some fluorinecontaining, highly functionalized cycloalkane derivatives. The synthetic protocol involves the stereoselective epoxidation of selected substituted cyclohexenes as model compounds, followed by regioselective opening of epoxides under various conditions with fluorinating reagents Deoxofluor and XtalFluor-E

Optical bandgap engineering in nonlinear silicon nitride waveguides

Silicon nitride is awell-established material for photonic devices and integrated circuits. It displays a broad transparency window spanning from the visible to the mid-IR and waveguides can be manufactured with low losses. An absence of nonlinear multi-photon absorption in the erbium lightwave communications band has enabled various nonlinear optic applications in the past decade. Silicon nitride is a dielectric material whose optical and mechanical properties strongly depend on the deposition conditions. In particular, the optical bandgap can be modified with the gas flow ratio during low-pressure chemical vapor deposition (LPCVD). Here we show that this parameter can be controlled in a highly reproducible manner, providing an approach to synthesize the nonlinear Kerr coefficient of the material. This holistic empirical study provides relevant guidelines to optimize the properties of LPCVD silicon nitride waveguides for nonlinear optics applications that rely on the Kerr effect

Szíjhajtással kombinált szerszámgépek főhajtóműveinek numerikus dinamikai vizsgálata Simulink környezetben

Ezen cikk a szíjhajtással kombinált szerszámgépek főhajtásainak numerikus dinamikai vizsgálatával/modellezésével foglalkozik Simulink környezetben. A korábbi szíjhajtás, illetve a szabad szíjágak modellje kiegészül a szíjtárcsa mentén kialakuló szíj alkotta rezgőrendszerrel, ami már önmagában egy bonyolult matematikai problémát jelent. Mérési eredmények alapján könnyen belátható, hogy különféle szíjhajtások különböző módon viselkednek, ez indokolja az előbb említett lehetséges pontosításnak a szükségességét. Az így kapott újfajta, kiegészített rendszermodell vizsgálata alkalmas lehet pontosabb számítások elvégzésére, amely már a hajtás tervezési szakaszában is egy jó becsléssel szolgálhat adott tervezési paraméterek mellett, a hajtás dinamikai viselkedésre vonatkozóan