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Simulating the Effects of Substrate Pre-Heating on the Final Structure of Steel Parts Built by Laser Powder Deposition
Tool steel parts built by laser powder deposition often present a heterogeneous distribution of
properties caused by the complex structural transformations that occur during the deposition
process. A model describing these transformations has been developed. It couples finite element
heat transfer calculations with transformation kinetic theory to predict the final microstructure
and properties of the material and their variation across a laser powder deposited part.
Pre-heating is often used to reduce the residual stresses and the risk of thermal distortion and
cracking. However, this changes the heat transfer conditions and affects the final microstructure
and properties. In this work the proposed model was used to evaluate the effects of substrate preheating on the final hardness distribution. The results show that the final hardness depends
considerably on the initial temperature of the substrate.Mechanical Engineerin
Out-of-plane seismic response of stone masonry walls: experimental and analytical study of real piers
This paper presents the application of an existing simplified displacement-based procedure to the
characterization of the nonlinear force-displacement relationship for the out-of-plane behaviour of
unreinforced traditional masonry walls. According to this procedure, tri-linear models based on three
different energy based criteria were constructed and confronted with three experimental tests on
existing stone masonry constructions. Moreover, a brief introduction is presented regarding the main
characteristics of the in situ cyclic testing recently carried out using distributed loads, as well as results
obtained during the experimental campaigns performed. The comparison between the experimental and the analytical results are presented and discussed
Impurities near an Antiferromagnetic-Singlet Quantum Critical Point
Heavy fermion systems, and other strongly correlated electron materials,
often exhibit a competition between antiferromagnetic (AF) and singlet ground
states. Using exact Quantum Monte Carlo (QMC) simulations, we examine the
effect of impurities in the vicinity of such AF- singlet quantum critical
points, through an appropriately defined impurity susceptibility, .
Our key finding is a connection, within a single calculational framework,
between AF domains induced on the singlet side of the transition, and the
behavior of the nuclear magnetic resonance (NMR) relaxation rate . We
show that local NMR measurements provide a diagnostic for the location of the
QCP which agrees remarkably well with the vanishing of the AF order parameter
and large values of . We connect our results with experiments on
Cd-doped CeCoIn
The Redner - Ben-Avraham - Kahng cluster system
We consider a coagulation model first introduced by Redner, Ben-Avraham and
Krapivsky in [Redner, Ben-Avraham, Kahng: Kinetics of 'cluster eating', J.
Phys. A: Math. Gen., 20 (1987), 1231-1238], the main feature of which is that
the reaction between a j-cluster and a k-cluster results in the creation of a
|j-k|-cluster, and not, as in Smoluchowski's model, of a (j+k)-cluster. In this
paper we prove existence and uniqueness of solutions under reasonably general
conditions on the coagulation coefficients, and we also establish
differenciability properties and continuous dependence of solutions. Some
interesting invariance properties are also proved. Finally, we study the
long-time behaviour of solutions, and also present a preliminary analysis of
their scaling behaviour.Comment: 24 pages. 2 figures. Dedicated to Carlos Rocha and Luis Magalhaes on
the occasion of their sixtieth birthday
The Redner - Ben-Avraham - Kahng coagulation system with constant coefficients: the finite dimensional case
We study the behaviour as of solutions to the
Redner--Ben-Avraham--Kahng coagulation system with positive and compactly
supported initial data, rigorously proving and slightly extending results
originally established in [4] by means of formal arguments.Comment: 13 pages, 1 figur
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