1,721,038 research outputs found
Evaluation of the residual prestressing force in reinforced concrete elements by means of prestress release tests
No full textPrestressed reinforced concrete elements can be subjected to relevant stress variations over time because of steel stress relaxation and concrete time- dependent deformation, often amplified in case of possible steel strands failure, caused by progressive material degradation. This will lead to a significant reduction of the overall prestressing force. The age of the majority of Italian bridges, originally designed without particular attention to durability, is quickly approaching their design service life. In this framework, the need to periodically evaluate the deterioration level of the materials becomes of paramount importance, in particular for prestressed steel strands; this will allow the attainment of a reliable estimation of the residual prestressing force in prestressed reinforced concrete beams (common in bridges and viaducts). The present paper aims at evaluating the reliability of a semi-destructive technique which can be used for performing prestress release tests on reinforced concrete elements by means of the removal of small portions of concrete, often involving only a portion of the concrete cover. Tests were performed on reinforced concrete columns subjected to a predefined compressive axial load, in order to have a direct comparison between the experimental deformation, measured by means of strain gauges, and the effective axial stress, applied through the experimental set-up. Different parameters have been considered during the tests, such as the geometric sawing configuration and the order of the steps performed before the removal of the concrete sample, evaluating their effect on the strain release, with the aim of proposing a reliable procedure easily applicable during in-situ tests
Interplay between spinal cord and cerebral cortex metabolism in amyotrophic lateral sclerosis
No full textAmyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder, characterized by a degeneration of upper and lower motor neurons leading to a progressive muscular paralysis. Although median survival most often averages 3–4 years, the large variability of its course (Calvo et al., 2017) raises an urgent need to develop biomarkers able to characterize the mechanisms underlying disease progression and to improve the diagnostic yield of clinical and neuro-physiological evaluation.
Most studies in this setting focused on cortical response to ALS. Among these approaches, brain PET studies with 18F-fluorodeoxyglucose (FDG) already reported a significant reduction in glucose metabolism (Pagani et al., 2014) in motor and premotor cortex (Kiernan et al., 1994; Abrahams et al., 1996, 2005). By contrast, involvement of the spinal cord has been characterized in relatively lower detail, mostly because of the anatomical features of this structure that limit the standardization of its evaluation. Consequently, a large uncertainty still exists about the mechanisms underlying ALS-induced damage in the spinal cord and its relationship with cortical impairment. We recently reported the potential of the Hough transform in delineating spinal cord structure and metabolic activity in a population of ALS patients subjected to FDG PET/CT (Marini et al., 2016). Specifically, this classical pattern recognition approach for the automatic identification of straight lines in the image has been recently extended to the recognition of more complex shapes. This computational 3D approach enabled the extraction of spinal cord metabolic information from whole body images and per- mitted us to document increased glucose consumption, possibly representing a potential and independent prognostic marker (Marini et al., 2016).
In the present study, we simultaneously analysed brain and spinal cord FDG uptake in a series of prospectively recruited patients submitted to brain and wholebody PET/CT
Defect Detection In Vehicle Painting: Case Study
Full text linkDefect detection is a cross-sectoral problem that is being intensively addressed in manufacturing, primarily
with the help of computer vision and image processing-based systems. From fabric to surface to mechanical
parts, defect detection approaches have assisted human operators and reduced human eye strain. However, many case-specific challenges arise in vehicle painting. Although few authors have addressed them, research is still active due to the high-quality demand and competition in manufacturing. In this study, we present a case study on paint defect detection in IVECO vehicle production, listing the problem description, challenges, literature review, and proposed solution
Exploring Latent Space Using a Non-linear Dimensionality Reduction Algorithm for Style Transfer Application
No full textA latent space represents data by embedding them in a multidimensional vector space. In this way an abstract estimation of any complex domain could be created. Empirical approach for exploring the latent space generated by known pre-trained model of human face images using a nonlinear dimensionality reduction algorithm is presented in this paper. One aim was to find more detailed entangled features (beard and hair color) between the real images and their representation, in artistic face portrait application. Experimental results showed that sparse vectors in the latent space could be useful to obtain optimal results with relatively low effort. To evaluate our work, we present the results of a survey that was sent to 25 thousand subscribers of the real world application and got around 360 responses. The main goal of the survey was to find some quantitative measurements that can be used in our research
Experimental and numerical evaluation of fiber-matrix interface behaviour of different FRCM systems
Full text linkFiber Reinforced Cementitious Matrix (FRCM) composites are a relatively new strengthening system family, whose mechanical behavior is strongly affected by the wide array of possible inorganic matrices and composites fabrics that can be used and coupled together. Structural tests highlighted that global capacity of the system is strongly affected by fabric-matrix adhesion mechanism. In the present paper, the experimental results of tensile and single-lap shear tests, aimed to define mechanical properties of four FRCM types, are discussed and compared. For each system type, the failure modes for both types of test have been physically identified and clarified. The following development of detailed finite element models, carefully reproducing the mechanical behavior of the different layers of the strengthening system, allowed for the proposal of a reliable shear stress-slip relation for the fiber-matrix interface. The experimental outcomes showed the relevant dispersion of the results in terms of performance, effectiveness and failure mechanisms exhibited by the different FRCM types while the numerical interpretation allowed for a better understanding of the reasons and the parameters behind them
Bond behavior and tensile properties of FRCM composites applied on masonry panels
No full textThe presented experimental study is aimed at improving the knowledge about the tensile behavior
and bond performance of FRCMs, in order to improve their effectiveness and suggest qualification methods
before the application of these composite materials on masonry structures.Tensile tests and single-lap shear tests
were performed on FRCM composites based on bi-directional carbon and glass grids and on natural hydraulic
lime mortar. In order to improve the adhesion between fibers and matrix and to limit the possible slip between
them, an adhesion promoter has been used. The application of Digital Image Correlation technique allowed
to obtain complete displacement and strain maps on the surface of the specimens tested, both in tensile and
bond tests. Experimental results show good performance of the strengthening systems, with some typical failure
modes. The proposed test methods, which led to reliable results, could also provide useful suggestions for the
standardization of materials qualification process
Prime convolutional model: Breaking the ground for theoretical explainability
Full text linkIn this paper, we propose a new theoretical approach to Explainable AI. Following the Scientific Method, this approach consists of formulating, on the basis of empirical evidence, a mathematical model to explain and predict the behaviors of Neural Networks. We apply the method to a case study created in a controlled environment, which we call Prime Convolutional Model (p-Conv for short). p-Conv operates on a dataset consisting of the first one million natural numbers and is trained to identify the congruence classes modulo a given integer m. Its architecture uses a convolutional-type neural network that contextually processes a sequence of B consecutive numbers for each input. We take an empirical approach and exploit p-Conv to identify the congruence classes of numbers in a validation set using different values for m and B. The results show that the different behaviors of p-Conv (i.e., whether it can perform the task or not) can be modeled mathematically in terms of m and B. The inferred mathematical model reveals interesting patterns able to explain when and why p-Conv succeeds in performing task and, if not, which error pattern it follows
Experimental Study on Masonry Panels Strengthened by GFRP: The Role of Inclination between Mortar Joints and GFRP Sheets
No full textFor the shear strengthening of masonry walls, different configurations for FRP sheets are currently used in real application, such as vertical, horizontal or diagonal strips. In the last configuration the FRP sheet is inclined with respect to the direction of mortar joints. In the experimental campaign presented in this paper, it is investigated whether the FRP-masonry bond could be affected by this inclination. In order to analyze this issue, three different typologies of masonry panels (with
different textures) retrofitted by FRP sheets, inclined of 45 degrees with respect to the vertical axis of the specimen, are subjected to single-lap shear tests. Results of shear tests are presented in terms of maximum debonding forces, force-elongation curves, failure modes and strain profiles along the specimens. The use of Digital Image Correlation (DIC) technique allowed to obtain complete strain maps on the surface of the specimens tested, with the purpose of investigating possible variations in
the strain field within the bonded area
EFFECT OF MATRIX ON BOND BETWEEN FRCM AND MASONRY
Full text linkFiber Reinforced Cementitious Matrix (FRCM) composite materials. Bi-directional carbon and glass grids were applied by using cementitious mortar or natural hydraulic lime mortar. Tests on bricks were carried out first without surface preparation and then after treating them with sandblasting, in order to investigate possible improvements on the maximum debonding force after increasing adhesion between matrix and substrate. The study is focused on the analysis of the influence of different properties of the matrix on bond between FRCM and masonry. The effect of an adhesion promoter, developed in order to improve the adhesion between fibers and matrix and to limit the possible slip between them, was investigated. All the samples were subjected to single-lap shear tests until failure. The use of Digital Image Correlation (DIC) technique allowed to obtain complete displacement and strain maps on the surface of the specimens tested. The experimental results show good performance of CFRCM and GFRCM strengthening systems in combination with the adhesion promoter
Biological Correlates of Dissociative Disorders: A Systematic Review on Biomarkers and Trauma Connections
No full textPathological dissociation is characterized by disruptions in consciousness, memory, identity, perception, and affect, often linked to trauma and observed across various psychiatric conditions. Previous reviews do not fully cover key biological correlates used as biomarkers and do not clearly define the trauma-dissociation link. Therefore, this systematic review gives an overview of the studies on biomarkers research of the most relevant findings in associations between dissociative disorders and biological correlates. Additionally, it seeks to explore potential links between specific trauma types and recurrent biomarkers. A total of 123 studies were included, highlighting the role of increased prefrontal cortex activation and reduced hippocampal volume as potential biomarkers for pathological dissociation. Altered connectivity in the limbic system, frequently tied to childhood trauma, further underscores the neurobiological basis of dissociative symptoms. Biochemical and genetic studies, while promising, present inconsistent results and require further validation. This review underscores the importance of identifying reliable biomarkers to improve diagnostic accuracy, inform personalized treatment strategies, and monitor therapeutic responses. Future research should aim to unify methodologies and explore novel approaches to enhance clinical applications
- …
