An investigation on the 'width and size effect' in the evaluation of the fracture energy of concrete

The parameters that describe the fracture behavior of concrete are crucial to investigate numerically the response of reinforced concrete (RC) structures. Among them, the fracture energy plays a key role in all those applications that aim to simulate the behavior of RC structures. The fracture energy is a characteristic property of a material but its experimental evaluation could be difficult for quasi-brittle materials such as concrete due to the "width effect" and "size effect" that can lead to some uncertainties in the definition of this parameter. This study presents the results of an experimental campaign conducted on notched specimens to evaluate the fracture energy of concrete. Concrete prisms with different sizes were tested using a three-point bending (TPB) set-up to evaluate the influence of the width and the size on the results. The setup has been designed to become potentially part of the ACI 446 report on fracture. Digital image correlation (DIC) was used to qualitatively and quantitatively study the strain field near the crack tip. Preliminary numerical simulations were performed to investigate the "width effect" in a discrete element framework. Copyright (C) 2017 The Authors. Published by Elsevier B.V

Numerical investigation of factors influencing the experimental determination of concrete fracture energy

The fracture energy is one of the most crucial parameters for the numerical investigation of damage propagation and failure in reinforced concrete members. The correct characterization of concrete fracture properties can be compromised by different laboratory limitations, such as specimens size, mode of control, loading rate and the test apparatus. Nowadays limited recommendations exist concerning the experimental evaluation of fracture energy for normal and high strength concrete. In order to investigate the differences between different specimen sizes, evaluate the effect of mode of control and analyze the influence of different set-up on the fracture test, a numerical analysis supported by an experimental campaign is presented. The Lattice Discrete Particle Model (LDPM) has been used to simulate concrete and to provide realistic crack patterns and crack widths. In the first part of the study the position of the traveling crack tip is identified with two approaches and then used to investigate the strain rate distribution along the ligament. It is well-known that concrete is a visco-elastic material with strain-rate dependent fracture properties. For this reason in the second part of the study the potential influence of differences in loading rate on the effective fracture energy determined by the work of fracture method is investigated with simulated three-point bending tests of differently sized specimens and two notch depths

A comparison between the bond behavior of SRP and SRG strengthening systems applied to a masonry substrate

Strengthening and rehabilitation of existing masonry buildings is a topic that attracts the interest of the scientific community worldwide. Fiber reinforced polymer (FRP) composites have been largely employed for structural rehabilitation of masonry structures due to their ease of installation and their high strength-to-weight ratio, since the end of the previous century. Recently, fiber reinforced cementitious matrix (FRCM) composites have become an appealing alternative to traditional FRPs, because they employ an inorganic matrix to embed the fibers, which provides a better vapor compatibility with masonry substrate and better resistance to high temperatures than FRPs. To reduce the cost of carbon and glass fibers, the use of new types of fibers, such as high strength steel cords, has been explored. Steel reinforced polymer (SRP) and steel reinforced grout (SRG) are still moving their first steps in the world of structural rehabilitation, but they have shown potentials to become a suitable alternative to other FRP and FRCM composites, respectively. In this work, SRP and SRG composites are bonded to masonry blocks and tested using a direct single-lap shear test set-up to investigate the debonding phenomenon. Two different types of mortar grout are employed for the SRG. A comparison between SRP and SRG composites is presented in terms of debonding capacity and failure modes

Electroweak corrections to three-jet production in electron-positron annihilation

We compute the electroweak ${\cal O}(\alpha^3\alpha_s)$ corrections to three-jet production and related event-shape observables at electron-positron colliders. We properly account for the experimental photon isolation criteria and for the corrections to the total hadronic cross section. Corrections to the three-jet rate and to normalised event-shape distributions turn out to be at the few-per-cent level.Comment: 5 pages, 4 figures. v2: changed normalisation in Fig. 2, minor text revisions, version to appear in Phys.Lett.

A design methodology for compositional high-level synthesis of communication-centric SoCs

Systems-on-chip are increasingly designed at the system level by combining synthesizable IP components that operate concurrently while interacting through communication channels. CAD-tool vendors support this System-Level Design approach with high-level synthesis tools and libraries of interface primitives implementing the communication protocols. These interfaces absorb timing differences in the hardware-component implementations, thus enabling compositional design. However, they introduce also new challenges in terms of functional correctness and performance optimization. We propose a methodology that combines performance analysis and optimization algorithms to automatically address the issues that SoC designers may accidentally introduce when assembling components that are specified at the system level. Copyright 2014 ACM

A design methodology for compositional high-level synthesis of communication-centric SoCs.

ABSTRACT Systems-on-chip are increasingly designed at the system level by combining synthesizable IP components that operate concurrently while interacting through communication channels. CAD-tool vendors support this System-Level Design approach with high-level synthesis tools and libraries of interface primitives implementing the communication protocols. These interfaces absorb timing differences in the hardware-component implementations, thus enabling compositional design. However, they introduce also new challenges in terms of functional correctness and performance optimization. We propose a methodology that combines performance analysis and optimization algorithms to automatically address the issues that SoC designers may accidentally introduce when assembling components that are specified at the system level

System-Level Optimization of Accelerator Local Memory for Heterogeneous Systems-on-Chip

In modern system-on-chip architectures, specialized accelerators are increasingly used to improve performance and energy efficiency. The growing complexity of these systems requires the use of system-level design methodologies featuring high-level synthesis (HLS) for generating these components efficiently. Existing HLS tools, however, have limited support for the system-level optimization of memory elements, which typically occupy most of the accelerator area. We present a complete methodology for designing the private local memories (PLMs) of multiple accelerators. Based on the memory requirements of each accelerator, our methodology automatically determines an area-efficient architecture for the PLMs to guarantee performance and reduce the memory cost based on technology-related information. We implemented a prototype tool, called Mnemosyne, that embodies our methodology within a commercial HLS flow. We designed 13 complex accelerators for selected applications from two recently-released benchmark suites (Perfect and CortexSuite). With our approach we are able to reduce the memory cost of single accelerators by up to 45%. Moreover, when reusing memory IPs across accelerators, we achieve area savings that range between 17% and 55% compared to the case where the PLMs are designed separately

Eyelid fat grafting: indications, operative technique and complications; a systematic review

International audienceIntroduction - Many recent studies concerning autologous fat grafting in the eyelids have been published, mostly consisting of case reports and retrospective case series. However, no study on the overall complication or satisfaction rate associated with the various grafting techniques exists. We performed a comprehensive literature review to determine the outcomes and complications of eyelid fat grafting, as well as patient satisfaction.Methods - A systematic review of the literature using the PRISMA criteria was conducted. This protocol was registered at the Prospective Register of Systematic Reviews at the National Institute for Health Research.Results - Sixteen studies, representing 1,159 patients and published between June 2004 and December 2014, were included. Satisfactory results, judged by clinical examination, were observed in all studies. Few postoperative complications were reported.Conclusions - We demonstrated that the procedures were easy to perform, and achieved satisfactory and sustainable results with few complications in both reconstructive and cosmetic surgery. However, a wide disparity exists in the various fat harvesting, fat purification, and reinjection techniques. Further studies are required to assess the long-term outcomes. Our conclusions should be accepted cautiously due to the small number of articles and the lack of evidence in published studies.<br

From "traction bronchiectasis" to honeycombing in idiopathic pulmonary fibrosis: A spectrum of bronchiolar remodeling also in radiology?

The diagnostic and prognostic impact of traction bronchiectasis on high resolution CT scan (HRCT) in patients suspected to have idiopathic pulmonary fibrosis (IPF) is increasing significantly