Modeling anisotropic and rate-dependent plasticity in short-fiber reinforced thermoplastics

In this study, an anisotropic viscoelastic-viscoplastic macro-mechanical model is presented for short-fiber reinforced thermoplastics (SFRT). In injection molding of SFRT, the fiber orientation is influenced by the flow velocity profile which varies throughout the mold. The flow-induced orientation in the microstructure leads to anisotropy in the mechanical response. In addition to the mechanical anisotropy, SFRTs show time dependent behavior because of the thermoplastic matrix. The developed model captures the effects of both material orientation and loading rate on the yield behavior. In this study, uniaxial tests are performed at different strain rates and material orientations with samplescutfrominjectionmoldedplaques. Theexperimentalresultsshowthattheeffects of loading rate and material orientation on the yield are decoupled. The presented model takes advantage of this observation to simplify material characterization. An implicit integration scheme is used for the numerical implementation of the model as a UMAT in ABAQUS. Multiple relaxation times are used in order to capture the nonlinear pre-yield regime. An efficient method for obtaining the model parameters for different modes is proposed. Experimental results are used for validation of the model and a good agreement is observed for the prediction of viscoelastic and viscoplastic behavior

Long-term microstructural evolution of tungsten under heat and neutron loads

In nuclear fusion reactors, tungsten will be exposed to high neutron loads at high temper atures (>900 C). The evolution and degradation of the mechanical properties under these conditions is uncertain and therefore constitutes a major risk. Here, the microstructural evolution of tungsten under combined heat and neutron loads is studied, using a multi-scale approach incorporating clusters dynamics and a mean-field recrystallization model. The mean-field recrystallization model contains both nucleation in the bulk and at the grain boundaries. The cluster dynamics model includes the incorporation of loops in the dynamics of the dislocation network as a mechanism. The effects of bulk nucleation on the microstructural evolution are explored. The simulations predict a cyclically occuring neutron-induced recrystallization at all studied temperatures. Furthermore, the evolution of the irradiation hardening during neutron-induced recrystallization is assessed from the simulated microstructures.Comment: Submitted to peer-reviewed journa

Model-Based Testing of Internet of Things Protocols

Internet of Things (IoT) is a popular term to describe systems/devices that connect and interact with each other through a network, e.g., the Internet. These devices communicate with each other via a communication protocol, such as Zigbee or Bluetooth Low Energy (BLE), the subject of this paper. Communication protocols are notoriously hard to implement correctly and a large set of test-cases is needed to check for conformance to the standard. Many of us have encountered communication problems in practice, such as random mobile phone disconnects, difficulty obtaining a Bluetooth connection, etc. In this paper, we research the application of industry strength Model-Based Testing (MBT) within the IoT domain. This technique contributes to higher quality specifications and more efficient and more thorough conformance testing. We show how we can model part of the BLE protocol specification using the Axini Modeling Platform (AMP). Based on the model, AMP is then able to automatically test the conformance of a BLE device. With this approach, we found specification flaws in the official BLE specifications as well as conformance errors on a certified BLE system

Controlled irradiation hardening of tungsten by cyclic recrystallization

The economical lifetime of the divertor is a key concern for realizing nuclear fusion reactors that may solve the world's energy problem. A main risk is thermo-mechanical failure of the plasma-facing tungsten monoblocks, as a consequence of irradiation hardening induced by neutron displacement cascades. Lifetime extensions that could be carried out without prolonged maintenance periods are desired. In this work, the effects of potential treatments for extending the lifetime of an operational reactor are explored. The proposed treatments make use of cyclic recrystallization processes that can occur in neutron-irradiated tungsten. Evolution of the microstructure under non-isothermal conditions is investigated, employing a multi-scale model that includes a physically-based mean-field recrystallization model and a cluster dynamics model for neutron irradiation effects. The model takes into account microstructural properties such as grain size and displacement-induced defect concentrations. The evolution of a hardness indicator under neutron irradiation was studied. The results reveal that, for the given microstructure and under the assumed model behaviour, periodical extra heating can have a significant positive influence on controlling the irradiation hardening. For example, at 800 C, if extra annealing at 1200 C was applied after every 100 hrs for the duration of 1 hr, then the hardness indicator reduces from maximum 140 to below 70.Comment:

Ідентифікація системи підтримки прийняття рішень з урахуванням ризику на прикладі банківського кредитування

Розроблено систему підтримки прийняття рішень щодо банківського кредитування для юридичних і фізичних осіб з урахуванням ризику. Запропоновано здійснювати формалізацію системи підтримки прийняття рішень із використанням математичного апарату нечітких множин та розроблено алгоритм прийняття рішень на її основі.The decision-making support system concerning bank crediting for the legal and physical persons in view of venture is developed. It is offered to make formalization of decision-making support system with use of the mathematical apparatus of indistinct sets and the algorithm of decision-making on their basis is developed

Ceramica punica dal sito rurale di Truncu 'e Molas (Terralba, Sardegna)

No abstract available

Preventive Group Training Improves Children's Outcomes after Divorce:A Dutch Quasi-experimental Study

Worldwide, many children experience parental separation and divorce. This has a significant impact on their well-being, and emotional and behavioral functioning, and calls for prevention. To assess the effects of the Children of Divorce Intervention Program in the Netherlands (CODIP-NL) on 6- to 8-year-olds, we performed a quasi-experimental effect study. The study compared children receiving CODIP-NL (intervention: I, n = 104), children not receiving CODIP-NL but having divorced parents (divorced control: DC, n = 37), and children belonging to non-divorced families (non-divorced control: NDC, n = 138). Outcomes pertained to children's positive functioning, emotional and behavioral problems, and well-being. We assessed pre- to post-test differences in change in mother-reported outcomes between the intervention and control groups, and pre- to post-test differences in group leader reports. The intervention led to increases in mother-reported positive functioning (d = 0.97 I vs. DC; d = 1.04 I vs. NDC), and well-being (d = 1.00 I vs. DC; d = 0.84 I vs. NDC). Mother-reported child emotional and behavioral problems decreased after participation (total difficulties, d = 0.73 I vs. DC; d = 0.49 I vs. NDC). Group leader-reported pre- to post-test differences (