Search results for "reciproc"

Experimental and Numerical Analysis of Microstructure Evolution during Linear Friction Welding of Ti6Al4V

2015

Abstract Linear Friction Welding (LFW) is a solid state welding process used to joint bulk components. In the paper, an experimental and numerical study on LFW of Ti6Al4V titanium alloy is presented. A laboratory designed LFW machine has been used to weld the specimens with different contact pressure and oscillation frequency. The joint microstructure has been experimentally observed with SEM and EDS. A dedicated numerical model, able to predict temperature, strain and strain rate distribution as well as the phase volume fraction evolution, has been utilized to predict the final microstructure in the welded parts. It was found that complete transformation of the alpha phase into beta phase …

Numerical modelling of the linear friction welding process

2010

Linear friction welding (LFW) is a solid-state joining process applied to non-axisymmetric components. LFW involves joining of materials through the relative reciprocating motion of two components under an axial force. In such process the heat source is given by the frictional forces work decaying into heat determining a local softening of the material and proper bonding conditions due to both the temperature increase and the local pressure of the two edges to be welded. In the present work the authors present a numerical model of the linear friction welding process of AISI 1045 parts. The numerical model allowed to highlight the process mechanics and the physical conditions which must be r…

Doni funesti. Miti di scambi pericolosi nella letteratura latina

2018

«I doni sono come gli ami» avverte Marziale. «Catturano anche gli dèi» afferma Ovidio. «Sono l’inganno in cui di solito incappano i re» osserva Seneca. La forza calamitante del dono, la sua natura seducente e pericolosa, emerge con chiarezza dall’analisi del sapere mitico romano e delle sue riscritture letterarie. I Romani, del resto, conoscevano bene il potere attrattivo dei doni, la loro capacità di condizionare i comportamenti e le dinamiche di relazione. Erifile è soggiogata dalla collana di Armonia, Mida è accecato dalla sua fame d’oro, Creusa è ingannata dai doni nuziali; Didone brucia con sé quelli dell’amato, Semele e Fetonte ne saranno bruciati. Il dono promesso è un rischio, il do…

La fides e la fraus: i doni del tiranno nel Thyestes di Seneca

2019

Nel Thyestes, Seneca riscrive la pratica del dono (536, 984) come strumento della vendetta del tiranno, che ne sfrutta il potere di attrazione. Combinando la categoria della fides con il meccanismo della fraus, Atreo intende mettere in scena un inganno in grado di soddisfare le “inique aspettative” (spes improba, 295) di Tieste, che spera di ottenere il regno (regna nunc sperat mea, 289), e fornirgli una garanzia tangibile di pace (fides pacis, 294). Una tale dinamica prende la forma di un “dono simulato”, una pratica di reciprocità in cui Atreo svolge il ruolo del donatore (dans) e Tieste è indotto ad assumere quello del destinatario (accipiens). Il tiranno lo rappresenta come un modo per …

Numerical simulation of reciprocating turbulent flow in a plane channel

2009

Direct numerical simulation results were obtained for oscillatory flow with zero time mean (reciprocating flow) in a plane channel using a finite volume method, Crank-Nicolson time stepping and central approximation of the advection terms. A pressure gradient varying co-sinusoidally in time was imposed as the forcing term, and its frequency and amplitude were made to vary so as to span a range of regimes from purely laminar to fully turbulent. For the limiting cases of reciprocating laminar flow and steady-state turbulent flow, numerical results were validated against analytical solutions and classic experimental literature data, respectively. For general reciprocating flows, predictions we…

Reciprocal lower bound on modulus of curve families in metric surfaces

2019

We prove that any metric space $X$ homeomorphic to $\mathbb{R}^2$ with locally finite Hausdorff 2-measure satisfies a reciprocal lower bound on modulus of curve families associated to a quadrilateral. More precisely, let $Q \subset X$ be a topological quadrilateral with boundary edges (in cyclic order) denoted by $\zeta_1, \zeta_2, \zeta_3, \zeta_4$ and let $\Gamma(\zeta_i, \zeta_j; Q)$ denote the family of curves in $Q$ connecting $\zeta_i$ and $\zeta_j$; then $\text{mod} \Gamma(\zeta_1, \zeta_3; Q) \text{mod} \Gamma(\zeta_2, \zeta_4; Q) \geq 1/\kappa$ for $\kappa = 2000^2\cdot (4/\pi)^2$. This answers a question concerning minimal hypotheses under which a metric space admits a quasiconfor…

SURFACE SUBGROUPS OF RIGHT-ANGLED ARTIN GROUPS

2007

We consider the question of which right-angled Artin groups contain closed hyperbolic surface subgroups. It is known that a right-angled Artin group $A(K)$ has such a subgroup if its defining graph $K$ contains an $n$-hole (i.e. an induced cycle of length $n$) with $n\geq 5$. We construct another eight "forbidden" graphs and show that every graph $K$ on $\le 8$ vertices either contains one of our examples, or contains a hole of length $\ge 5$, or has the property that $A(K)$ does not contain hyperbolic closed surface subgroups. We also provide several sufficient conditions for a \RAAG to contain no hyperbolic surface subgroups. We prove that for one of these "forbidden" subgraphs $P_2(6)$, …

Inheritance of resistance to aBacillus thuringiensistoxin in a field population of diamondback moth (Plutella xylostella)

1995

Inheritance of resistance to the Bacillus thuringiensis Berl. CryIA(b) crystal protein was studied in Plutella xylostella L. (diamondback moth). A field population 50-fold more resistant to CryIA(b) than a control susceptible strain was used. Dose-mortality curves of the resistant population, the susceptible strain and the F 1 from the two reciprocal crosses were compared. Resistance transmission to the F 1 was dependent on the sex of the resistant progenitor. Sex ratio of the survivors to high doses of CryIA(b) in the F 1 of the two reciprocal crosses did not corroborate the preliminary hypothesis of resistance being due to a recessive sex-linked allele. Since, in a previous work, the loss…

Beneficium e iniuria. Rappresentazioni del dono e dell’offesa nel De beneficiis di Seneca

2018

Informal male caregivers in the city of Valencia. An experience of reciprocity

2018

Este artículo forma parte de un estudio de la Universidad de Valencia donde se analiza la percepción que algunos hombres tienen acerca del cuidado de personas adultas (mayores y/o discapacitadas) que ellos realizan de manera informal en su entorno familiar en la ciudad de Valencia. A través de entrevistas en profundidad, identificamos, la responsabilidad que estos hombres se toman con la persona cuidada a través del establecimiento de procesos de reciprocidad. Dicha reciprocidad destaca como un elemento positivo a extraer de sus vivencias que permite reivindicar el cuidado como un valor positivo y no exclusivo de ningún género. This article is part of a study from the University of Valencia…