622 research outputs found
Reactive concurrent programming revisited
In this note we revisit the so-called reactive programming style, which
evolves from the synchronous programming model of the Esterel language by
weakening the assumption that the absence of an event can be detected
instantaneously. We review some research directions that have been explored
since the emergence of the reactive model ten years ago. We shall also outline
some questions that remain to be investigated
Advanced constitutive modeling for application to sheet forming
Continuum constitutive descriptions of plasticity suitable for finite element simulations of sheet forming processes are succinctly discussed. Although multi-scale approaches allow for a more explicit representation of the physical deformation mechanisms occurring at microscopic scales, they are usually not suitable for industrial applications because of the quick turnaround time needed for process design simulations. Therefore, advances in classical concepts such as plastic anisotropy and strain hardening are still very much in demand. This article describes possible ways to make use of multi-scale results for application to sheet metal forming simulations.11Ysciescopu
Interacting Agents and Continuous Opinions Dynamics
We present a model of opinion dynamics in which agents adjust continuous
opinions as a result of random binary encounters whenever their difference in
opinion is below a given threshold. High thresholds yield convergence of
opinions towards an average opinion, whereas low thresholds result in several
opinion clusters. The model is further generalised to network interactions,
threshold heterogeneity, adaptive thresholds and binary strings of opinions.Comment: 21 pages, 13 figures.
http://www.lps.ens.fr/~weisbuch/contopidyn/contopidyn.htm
Thermodynamic modelling of P availability: the case of intercropping rhizosphere
Plants of chickpea and durum wheat were cultivated as sole-‐crop and intercrop in a rhizobox deviceaccording to a substitutive design. Unplanted soil was used as a control treatment. The soil used was a noncarbonated Luvisol with a neutral pH. Plants were harvested at the chickpea flowering stage. The pH, Pavailability and dissolved Ca were measured in soil as extracted by water and CaCl2 (1 and 10 mM). A set ofthermodynamic models were used (i.e. CD MUSIC; Nica Donnan; ion exchange) to simulate and understandmeasured P availability variations in each treatment
The Effect of Spatial Design on User Memory Performance Using the Method of Loci in VR
Based on the Method of Loci, the following experiment compares the effect of two different virtual environments on participants' memory performance. The primary task consists of remembering a sequence of random playing cards. Each virtual environment is based on a different architectural style with a different layout. One is inspired by a Palladian style architecture, and the other by a Modern curved architecture
Observations on the Nonlinear Unloading Behavior of Advanced High Strength Steels
The unloading behavior was compared for three different steel grades: a dual-phase steel, a transformation-induced plasticity steel, and a twinning-induced plasticity steel. Steels that harden by phase transformation or deformation twinning exhibited a smaller component of microplastic strain during unloading and a smaller reduction in the chord modulus compared to the conventional hardening steel. As a result, unloading is closer to pure elastic unloading when the TRIP effect or TWIP effect is active.X111513sciescopu
Evaluation of constitutive models for springback prediction in U-draw/bending of DP and TRIP steel sheets
U-draw/bending experiments and simulations were performed to investigate the characteristics of springback in sheet metals. The finite element method is frequently used for the simulation of springback, but the predictions are strongly influenced by the constitutive models such as yield criteria and hardening laws. In the present study, springback of DP and TRIP steel sheets after U-draw/bending was predicted with a finite element analysis. Various yield functions were considered, namely, the isotropic von Mises and anisotropic Hill models. For strain hardening, isotropic, non-linear kinematic and combined isotropic-kinematic hardening models were considered. In order to characterize the isotropic hardening behavior, both uniaxial and balanced biaxial (hydraulic bulge) tension tests were carried out. For the characterization of the combined isotropic-kinematic hardening model, forward-reverse simple shear tests were conducted. The springback predictions were greatly influenced by the choice of the hardening model but slightly affected by the choice of the yield criterion. The kinematic hardening and combined isotropic-kinematic hardening models provided satisfactory predictions for DP590 and TRIP590 sheets, respectively. Due to an extended measurable strain range, the use of the flow curves from the hydraulic bulge test led to more reliable results than those of uniaxial tension.ope
Application of the Virtual Fields Method to determine dynamic properties at intermediate strain rates
Crash analysis simulation is now very important in automotive industry to assess
automotive crashworthiness and safety. In order to acquire reliable crash simulation results,
precise material behaviors at intermediate strain rates should be used as input data. To determine
the stress-strain curves at various strain rates, the number of expensive and complicated
experiments is large. The present study aims at determining the stress-strain curves of sheet
metals at various strain rates from a single dynamic experiment. A new type of high speed tensile
tester for sheet metal specimens was built and high speed tensile tests were carried out. Full-field
heterogeneous strain fields were measured by a digital image correlation technique using a highspeed camera. The load data was acquired from strain gauges attached to the elastic deformation
region on the specimen. Then, an inverse identification scheme with a rate dependent hardening
law was applied to retrieve dynamic parameters. The stress-strain curves of advanced high
strength steel at intermediate strain rates (100 /s - 300 /s) were successfully obtained from a
single experiment.11Ysciescopu
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