Size-effect independence of hybrid fiber-reinforced roller-compacted concrete fracture toughness

The present paper aims to prove the size-effect independence of Hybrid Fiber-Reinforced RCC (HyFR-RCC) fracture toughness determined through the Modified Two-Parameter Model (MTPM). A micromechanical numerical model is applied to simulate the fracture behavior of seven series of single edge-notched specimens, made of both plain-RCCs and FR-RCCs (single and hybrid reinforcements), subjected to three-point bending. The MTPM is applied to the numerical load vs CMOD curves to compute the fracture toughness. A comparison with experimental values, available in the literature, is performed. Therefore, RCC specimens with different sizes are numerically simulated and the fracture toughness is analytically determined through the MTPM, proving the size-effect independence

Observing the high redshift universe using the VIMOS-IFU

We describe the advantages of using Integral Field Spectroscopy to observe deep fields of galaxy. The VIMOS Integral Field Unit is particularly suitable for this kind of studies thanks to its large field-of-view (~ 1 arcmin^2). After a short description of the VIMOS-IFU data reduction, we detail the main scientific issues which can be addressed using observations of the Hubble Deep Field South with a combination of Integral Field Spectroscopy and broad band optical and Near-Infrared imaging.Comment: 4 pages, accepted for publishing in AN (ref. proc. of Euro3D Science workshop, IoA Cambridge, May 2003

A novel methodology for fatigue assessment of Ductile Cast Iron (DCI) with solidification defects

In the present research work, the fatigue strength assessment of a DCI containing solidification defects is theoretically carried out by means of a procedure implementing: (i) a defect content analysis, (ii) the varea-parameter model, and (iii) the multiaxial critical plane-based criterion by Carpinteri at al. An experimental campaign available in the literature, performed on DCI specimens under multiaxial fatigue loading, is analysed. The comparison between the obtained results and the experimental data shows a quite satisfactory agreement, highlighting the criterion accuracy

ZWT: A new cross-platform graphical interface framework for Java applications

The Java Programming Language revolutionized the world of software development in the last decades. Thanks to its portability, Java makes it possible to develop software that can run everywhere, in a truly cross-platform computing environment. Although running the same Java code anywhere works smoothly on major desktop and server platforms, this becomes much more complicated when different devices and platforms, such as smartphones or embedded systems, are taken into account. Furthermore, even if we consider devices that natively support the Java programming language, the same application may not run without re-writing part or the entire source code. This is mainly due to the existence of platform specific libraries for accessing input/output peripherals or system-specific features. In particular, the main limitation is usually associated to the different APIs that must be used for programming the Graphical User Interface (GUIs). In this paper, we present a novel framework that can be used by developers to write Java applications with portable GUIs that are truly platform-independent and thus can run on different systems such as PCs, Workstations, Android devices or mobile phones and embedded systems with Java MicroEdition (Java ME)

Experimental and numerical study on the fatigue behaviour of the shot-earth 772

The present research work is devoted to the mechanical, fracture and fatigue experimental characterization of the shot-earth 772, with a particular attention to its fatigue behaviour. To such an aim, an extensive experimental program has been carried out, consisting of: (i) flexural and compression tests, (ii) three-point bending fracture tests, and (iii) bending and compression cyclic tests. Moreover, a FE numerical model is employed to simulate both the above bending and compression cyclic tests, after the input data validation performed by simulating the above fracture tests. The numerical fatigue lifetimes are compared with the corresponding experimental ones for both pulsating bending and compression, highlighting the model accuracy. Finally, the contours of both the damage parameter and the reduced Young modulus are plotted showing the evolution of fatigue damage

Lifetime estimation for 316 stainless steel specimens by using a critical plane approach

The lifetimes of 316 stainless steel specimens are herein evaluated using the multiaxial critical plane-based criterion by Carpinteri et al. for high-cycle fatigue (HCF) loading with constant amplitude. In the present paper, the stress-based version of such a criterion is applied to assess the results of experimental tests under HCF triaxial loading, the hollow cylindrical dog-bone specimens being subjected to a quenching heat treatment. The analytical results of fatigue life and initial crack plane orientation are compared with the experimental data

Crack path estimation in the shot-earth 772 by a discrete element method

In the present paper, the fracture behaviour of the shot-earth 772, in terms of crack path, is numerically investigated. To such an aim, a version of the lattice discrete element method is used to numerically simulate fracture toughness testing performed, on the shot-earth 772, by employing the Modified Two-Parameter model. A comparison between the numerical crack path and the experimental ones is performed, highlighting as the lattice discrete element method is able to capture the kinked crack shape, typical of quasi-brittle material

HeII emitters in the VIMOS VLT Deep Survey: PopIII star formation or peculiar stellar populations in galaxies at 2<z<4.6?

The aim of this work is to identify HeII emitters at 2<z<4.6 and to constrain the source of the hard ionizing continuum that powers the HeII emission. We have assembled a sample of 277 galaxies with a high quality spectroscopic redshift at 2<z<4.6 from the VVDS survey, and we have identified 39 HeII1640A emitters. We study their spectral properties, measuring the fluxes, equivalent widths (EW) and FWHM for most relevant lines. About 10% of galaxies at z~3 show HeII in emission, with rest frame equivalent widths EW0~1-7A, equally distributed between galaxies with Lya in emission or in absorption. We find 11 high-quality HeII emitters with unresolved HeII line (FWHM_0<1200km/s), 13 high-quality emitters with broad He II emission (FWHM_0>1200km/s), 3 AGN, and an additional 12 possible HeII emitters. The properties of the individual broad emitters are in agreement with expectations from a W-R model. On the contrary, the properties of the narrow emitters are not compatible with such model, neither with predictions of gravitational cooling radiation produced by gas accretion. Rather, we find that the EW of the narrow HeII line emitters are in agreement with expectations for a PopIII star formation, if the episode of star formation is continuous, and we calculate that a PopIII SFR of 0.1-10 Mo yr-1 only is enough to sustain the observed HeII flux. We conclude that narrow HeII emitters are either powered by the ionizing flux from a stellar population rare at z~0 but much more common at z~3, or by PopIII star formation. As proposed by Tornatore et al. (2007), incomplete ISM mixing may leave some small pockets of pristine gas at the periphery of galaxies from which PopIII may form, even down to z~2 or lower. If this interpretation is correct, we measure at z~3 a SFRD in PopIII stars of 10^6Mo yr^-1 Mpc^-3 qualitatively comparable to the value predicted by Tornatore et al. (2007).Comment: accepted for publication in A&