1,266 research outputs found
Lagrange's discrete model of the wave equation in dimension greater than one
A celebrated theorem of Lagrange states that a solution of the wave equation
with one-dimensional space variable is the uniform limit, as N tends to
infinity, of a second order ODE obtained from a mechanical model discretizing a
string as N identical harmonic oscillators. Answering to a question posed by G.
Gallavotti we generalize this result to the case of any space dimension
AI Driven IoT Web-Based Application for Automatic Segmentation and Reconstruction of Abdominal Organs from Medical Images
Medical imaging technology has rapidly advanced in the last few decades, providing detailed images of the human body. The accurate analysis of these images and the segmentation of anatomical structures can produce significant morphological information, provide additional guidance toward subject stratification after diagnosis or before a clinical trial, and help predict a medical condition. Usually, medical scans are manually segmented by expert operators, such as radiologists and radiographers, which is complex, time-consuming and prone to inter-observer variability. A system that generates automatic, accurate quantitative organ segmentation on a large scale could deliver a clinical impact, supporting current investigations in subjects with medical conditions and aiding early diagnosis and treatment planning. This paper proposes a web-based application that automatically segments multiple abdominal organs and muscle, produces respective 3D reconstructions and extracts valuable biomarkers using a deep learning backend engine. Furthermore, it is possible to upload image data and access the medical image segmentation tool without installation using any device connected to the Internet. The final aim is to deliver a web- based image-processing service that clinical experts, researchers and users can seamlessly access through IoT devices without requiring knowledge of the underpinning technology
Hierarchical Framework for Automatic Pancreas Segmentation in MRI Using Continuous Max-flow and Min-Cuts Approach
Accurate, automatic and robust segmentation of the pancreas in medical image scans remains a challenging but important prerequisite for computer-aided diagnosis (CADx). This paper presents a tool for automatic pancreas segmentation in magnetic resonance imaging (MRI) scans. Proposed is a framework that employs a hierarchical pooling of information as follows: identify major pancreas region and apply contrast enhancement to differentiate between pancreatic and surrounding tissue; perform 3D segmentation by employing continuous max-flow and min-cuts approach, structured forest edge detection, and a training dataset of annotated pancreata; eliminate non-pancreatic contours from resultant segmentation via morphological operations on area, curvature and position between distinct contours. The proposed method is evaluated on a dataset of 20 MRI volumes, achieving a mean Dice Similarity coefficient of 75.5 ± 7.0% and a mean Jaccard Index coefficient of 61.2 ± 9.2%
Experimental tests of solar collectors prototypes systems
Solar thermal collectors represent one of the most widely used technologies for heat production from renewable energy sources. To increase efficiency and to not increase too much cost different type of solar collectors, and in particular of evacuated tube collectors have been realized. In order to compare performance, tests at different conditions and in different configurations have to be performed. The aim of this paper is to establish the performance of a new prototype via an experimental evaluation of the performance in different conditions and configurations of three collectors. The prototype is particular owing to his new head configuration that permits an innovative parallel configuration way. Therefore, parallel and series configurations have been analyzed applying the UNI-EN 12975, in a steady-state regime. The efficiencies of the two configurations have been tested for different flow rates and different inflow water temperatures. The experimental results show that, with the same input flow rate to the single collector, the parallel configuration has higher performance than the series one, reaching 15% higher level of efficiency. Thus, it seems that these prototypes in optimized configuration can lead to a systems improvement, thereby increasing the overall energy production or giving the same energy production with smaller collector area. © 2015 Published by Elsevier Ltd
Techno-economic analysis of hydrogen production using biomass gasification. A small scale power plant study
Hydrogen has the potential to be a clean alternative to the fossil fuels currently used. This is especially true if hydrogen is
manufactured from renewable resources such as biomass. However, hydrogen from biomass faces techno and economic challenges
especially in the small size required for the decentralized hydrogen production. In this purpose, a techno economic analysis was
carried out on small scale (100kWth) system. The plant is mainly composed of gasifier (double bubbling fluidized bed reactor)
coupled with a Portable Purification Unit (PPS: catalytic filter candles, Water Gas Shift and Pressure Swing Absorption). This
work focuses on system costs to identify barriers to the development of this technology. A sensitivity analysis was conducted to
study hydrogen production cost as a function of capital cost, operating cost and hydrogen production efficiency. The results
showed that although efficiency of the production system is the main factor to fall production cost, it cannot be able to reduce costs
to favorable level alone. In other words, PPS cost recognized as the major cost is requisite to go down. Therefore, the 50%
reduction of PPS cost and the variation of steam to biomass from 1 to 1.5 allow the special cost to fluctuate between 12.75-9.5
€/kg
Morphological and multi-level geometrical descriptor analysis in CT and MRI volumes for automatic pancreas segmentation
Automatic pancreas segmentation in 3D radiological scans is a critical, yet challenging task. As a prerequisite for computer-aided diagnosis (CADx) systems, accurate pancreas segmentation could generate both quantitative and qualitative information towards establishing the severity of a condition, and thus provide additional guidance for therapy planning. Since the pancreas is an organ of high inter-patient anatomical variability, previous segmentation approaches report lower quantitative accuracy scores in comparison to abdominal organs such as the liver or kidneys. This paper presents a novel approach for automatic pancreas segmentation in magnetic resonance imaging (MRI) and computer tomography (CT) scans. This method exploits 3D segmentation that, when coupled with geometrical and morphological characteristics of abdominal tissue, classifies distinct contours in tight pixel-range proximity as “pancreas” or “non-pancreas”. There are three main stages to this approach: (1) identify a major pancreas region and apply contrast enhancement to differentiate between pancreatic and surrounding tissue; (2) perform 3D segmentation via continuous max-flow and min-cuts approach, structured forest edge detection, and a training dataset of annotated pancreata; (3) eliminate non-pancreatic contours from resultant segmentation via morphological operations on area, structure and connectivity between distinct contours. The proposed method is evaluated on a dataset containing 82 CT image volumes, achieving mean Dice Similarity coefficient (DSC) of 79.3 ± 4.4%. Two MRI datasets containing 216 and 132 image volumes are evaluated, achieving mean DSC 79.6 ± 5.7% and 81.6 ± 5.1% respectively. This approach is statistically stable, reflected by lower metrics in standard deviation in comparison to state-of-the-art approaches
Energy and economic analysis of a residential Solar Organic Rankine plant
To answer the actual energy, water, economic, social and environmental challenges, renewable, distributed power plants need to
be developed. Among renewables, solar tri-generative power plants can be a solution where there is big low temperature
heating/cooling demand and small electricity demand, like many residential and industrial utilities. In this case, solar thermal
plants can produce thermal energy with low cost and high efficiency. The higher temperature heat not needed by the user can be
exploited via Organic Rankine Cycle to produce electrical energy and desalinized water via reverse osmosis. The present paper
analyses, via TRNSYS simulation, a system composed of 50 m2
of CPC solar thermal collectors, 3 m3
of thermal storage, a
synthetic heat transfer fluid, 3 kWe ORC, 8 kWth absorber, 200 l/h direct reverse osmosis desalination device. The system is able
to produce power, heating/cooling and fresh water needs for a residential house. Although system’s components are well known
technologies, the integration to a efficient and economic working system is still a challenge. Global energy and economic
analyses have been performed. Low temperature heating/cooling terminals allow to increase not only the use of thermal energy
but also the ORCand absorber efficiency. ORC-Absorber configuration and relative fluids and temperatures are central.
Government support and/or cost reduction of 30% are necessary to have positive NPV and acceptable PBT and IR
Special Attention to Physical Activity in Breast Cancer Patients during the First Wave of COVID-19 Pandemic in Italy: The DianaWeb Cohort
Recent evidence highlights that physical activity (PA) is associated with decreased recurrence risk, improved survival and quality of life for breast cancer (BC) patients. Our study aimed to explore patterns of increased/decreased PA, and sedentary behaviors among BC women of the DianaWeb cohort during the first wave of COVID-19 pandemic, and examined the association with residential locations, work changes, different modality used to increase PA, and quality of life. The study analyzed the questionnaires completed by the 781 BC women (age 54.68 ± 8.75 years on both December 2019 and June 2020. Results showed a decrease of 22%, 57%, and 26% for walking activity, vigorous activity, and total PA, respectively. Sitting/lying time increased up to 54.2% of the subjects recruited. High quality of life was associated with lower odds of being sedentary (p = 0.003). Our findings suggest that innovative health management fostering compliance with current guidelines for PA and active behavior should be implemented, especially in unpredictable emergency conditions
A Framework for Automatic Morphological Feature Extraction and Analysis of Abdominal Organs in MRI Volumes
The accurate 3D reconstruction of organs from radiological scans is an essential tool in computer-aided diagnosis (CADx) and plays a critical role in clinical, biomedical and forensic science research. The structure and shape of the organ, combined with morphological measurements such as volume and curvature, can provide significant guidance towards establishing progression or severity of a condition, and thus support improved diagnosis and therapy planning. Furthermore, the classification and stratification of organ abnormalities aim to explore and investigate organ deformations following injury, trauma and illness. This paper presents a framework for automatic morphological feature extraction in computer-aided 3D organ reconstructions following organ segmentation in 3D radiological scans. Two different magnetic resonance imaging (MRI) datasets are evaluated. Using the MRI scans of 85 adult volunteers, the overall mean volume for the pancreas organ is 69.30 ± 32.50cm3, and the 3D global curvature is (35.23 ± 6.83) × 10−3. Another experiment evaluates the MRI scans of 30 volunteers, and achieves mean liver volume of 1547.48 ± 204.19cm3 and 3D global curvature (19.87 ± 3.62) × 10− 3. Both experiments highlight a negative correlation between 3D curvature and volume with a statistical difference (p < 0.0001). Such a tool can support the investigation into organ related conditions such as obesity, type 2 diabetes mellitus and liver disease
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