Wavelet-Fourier CORSING techniques for multi-dimensional advection-diffusion-reaction equations

We present and analyze a novel wavelet-Fourier technique for the numerical treatment of multidimensional advection-diffusion-reaction equations based on the CORSING (COmpRessed SolvING) paradigm. Combining the Petrov-Galerkin technique with the compressed sensing approach, the proposed method is able to approximate the largest coefficients of the solution with respect to a biorthogonal wavelet basis. Namely, we assemble a compressed discretization based on randomized subsampling of the Fourier test space and we employ sparse recovery techniques to approximate the solution to the PDE. In this paper, we provide the first rigorous recovery error bounds and effective recipes for the implementation of the CORSING technique in the multi-dimensional setting. Our theoretical analysis relies on new estimates for the local a-coherence, which measures interferences between wavelet and Fourier basis functions with respect to the metric induced by the PDE operator. The stability and robustness of the proposed scheme is shown by numerical illustrations in the one-, two-, and three-dimensional case

Thermomechanical analysis of riveted carbon fiber laminates for aerospace applications

none3noExperimental fatigue tests performed on riveted carbon fiber laminates showed that the specimens, after some thousands of cycles, heated up, reaching around the rivet holes high temperatures. These temperatures if not properly controlled could be detrimental for the joint health. In order to understand the relative importance of all the mechanical and geometric parameters involved in the joint manufacturing, a numerical model of the joined carbon fiber laminates was developed using a commercial finite elements code. A simplified analytical model of heat transfer was then used to simulate the rivets thermal behavior under the assigned operating conditions: this model allowed comparisons with finite elements and can be used for simple thermal simulations. The numerical and analytical results were found in a good agreement with the available experimental results. The present research conclusions can be used for drawing better design rules in the definition of riveted carbon fiber laminates.openScarselli G.; Carrino S.; Nobile R.Scarselli, G.; Carrino, S.; Nobile, R

Effects of Waste Cooking Oil Biodiesel Use on Engine Fuel Consumption and Emissions: a Study on the Impact on Oxidation Catalyst and Particulate Filter

Abstract The wide use of biodiesel has been driven by its reduction potential on greenhouse emissions from diesel engines without significant technological modifications. In this study a diesel engine for non-road applications has been fuelled with Waste Cooking Oil biodiesel blended with commercial fossil fuel at 6% and 30% v/v. In line with literature trends, experimental results indicate a significant reduction of PM emissions and only a slight increase in NOx emissions. This study has been focused on diesel emissions and in particular on the analysis of PM/NO2 ratio in presence of the Diesel Oxidation Catalyst (DOC). In fact, although the NO2/NOx ratio on raw exhaust is almost unaffected, the use of biodiesel shows a slight reduction of the NO-NO2 light-off temperature. This reduction can ensure more favorable operating conditions for the Diesel Particulate Filter (DPF), and has a positive effect on fuel consumption reduction. In order to deeply analyze these issues, a numerical model of an Aftertreatment system (AS) representing the a DOC and a DPF has been developed and validated with experimental data

Can Infant Dyschezia Be a Suspect of Rectosigmoid Redundancy?

Infant dyschezia is a functional gastrointestinal disorder that occurs in children less than nine months of age. This disorder causes much anxiety among parents who consult different physicians when suspecting major intestinal problems. The aim of this study is to verify whether infant dyschezia involves an anatomic abnormality (redundancy) of the colon. In this retrospective study (48 months) we analyzed all the children younger than 9 months who came to our attention through the suspicion of gastrointestinal abnormality (Hirschsprung’s disease, anorectal malformations, colonic disorders or constipation). They all had a complete medical history, clinical examination and diagnostic tests, such as blood samples, suction rectal biopsy, a study of stool characteristics and, finally, a contrast enema. In cases with infant dyschezia, different colonic sizes and rectosigmoid length were measured, which created a ratio with the diameter of the second lumbar vertebra. These values were compared with those reported in the literature as normal for the age of one year. Of the 24 patients evaluated (mean age 4 months), 9 were excluded for different diagnoses (aganglionic megacolon, hypothyroidism, constipation). The comparison of the ratios obtained in the remaining 15 cases showed a significantly higher rectosigmoid length (redundancy) in children with dyschezia, 18.47 vs. 9.75 (p < 0.001). The rectosigmoid redundancy, a congenital anomaly already reported as a cause of refractory constipation, may be present in children with infant dyschezia

Transanal protrusion of intussusception can be sign of Waugh syndrome

Intussusception rarely occurs with transanal prolapse of intussusception (TAPI), this presentation may be a sign of Waugh's syndrome (WS), an association between intestinal malrotation and intussusception. The authors present the case of infant with an episode of TAPI, resolved with air enema, who required later diagnostic tests that showed the presence of WS, for which surgery was required after the resolution of the intussusception. At now we found only 72 cases reported of WS and some of them clinically presented with TAPI. In our opinion, patients with this type of presentation require a thorough radiological study of the intestine to rule out intestinal malrotations

What Is the Correct Way to Manage Children Requiring Gastrostomy? Single Center Experience

Children with complex medical issues often present different comorbidities that cause feeding difficulties. Gastrostomy is often helpful, and should be performed when nutritional supplementation is necessary for longer than 6 weeks. Recently, different techniques have been used for gastrostomy in children. The authors report on their experiences regarding the diagnostic and therapeutic management of children requiring gastrostomy. All patients managed in the last 10 years were reviewed, retrospectively. Everyone underwent investigation to exclude gastroesophageal reflux disease (GERD). A total of 148 patients: 111 cases (75%) were neurologically impaired patients, 18 (12%) had complex heart disease, 10 (6%) had metabolic diseases, 4 (3%) had fibrosis cystic, 4 (3%) had muscle disease, and one had chromosomopathy. After investigation, 49 patients had GERD. PEG was performed in 101 cases (68%), laparo-assisted gastrostomy was performed in 44 cases (29.7%), open gastrostomy was performed in three cases. At follow-up, all patients reported weight gain, but 13 cases had major complications. Currently, the surgeon has the possibility of choosing between several safe techniques for gastrostomy. In our experience, PEG is the most useful technique for patients without GERD, while a laparo-assisted technique is better for patients who require laparoscopic fundoplicatio

Control Strategy Influence on the Efficiency of a Hybrid Photovoltaic-Battery-Fuel Cell System Distributed Generation System for Domestic Applications☆

AbstractThe full exploitation of locally available renewable resources together with the reduction of system installation and management costs are key issues of diffused Distributed Generation (DG). In the given context, hybrid systems are already at an advanced stage of development which typically integrate several sub-systems. In such hybrid systems, Renewable Energy Sources generation systems (e.g. photovoltaic panels) are coupled to energy storage devices (electric batteries) and with programmable generators (a diesel generator or, more recently, with a sub-system based on fuel cells) allowing stable operations under a wide range of conditions. In this paper a solution which uses hydrogen and fuel cells as a programmable source is presented and is studied by means of a mixed experimental and numerical: a Hardware-In-Loop test bench designed and realized at the Department lab, able to reproduce the behavior of a hybrid system for domestic applications. The system is controlled by means of a rule-based control strategy acting on the common DC-bus whose optimization has a significant influence both on system design and on its overall system energy performances. Results show that Rule-Based strategy have a great potential towards cost reduction and components lifetime increase, while energy efficiency mainly depends on correct system sizing

Lentil fortified spaghetti: Technological properties and nutritional characterization

Lentil (Lens culinaris), consumed as a part of the diet worldwide, is a functional dietary ingredient that plays a function in human nutrition as a rich source of bioactive nutrients (low quantities of fat, sodium, and vitamin K; high content of potassium, essential amino acids, insoluble dietary fiber, and polyphenols). In this study spaghetti fortified with lentil flours (40% w/w) were developed and characterized. The addition of two different lentil flours significantly affected the sensory attributes and cooking properties of dry spaghetti. Therefore, the addition of carboxymethyl cellulose was adopted as technological option to improve the quality of fortified pasta; specifically, sensory acceptability, cooking loss, swelling index, and water absorption were studied. Chemical results highlighted that the addition of lentil to semolina significantly increased the content of lysine and threonine. It was observed an increase in essential and branched-chain amino acids. Contrary to what was expected, no increase in mono and polyunsaturated fatty acids was observed in fortified spaghetti, due to their loss during cooking, even after the addition of carboxymethyl cellulose

Advantages of GPU-accelerated approach for solving the Parker equation in the heliosphere

The increasing of experimental observations' accuracy and model complexity requires the development of a new class of numerical solvers. In this work, we present a GPU-accelerated approach for solving the Parker equation in the heliosphere using a stochastic differential equation (SDE) approach. The presented method was applied to a generic system of SDE using the CUDA programming language. Our approach achieves significant speedup compared to a CPU implementation, allowing us to efficiently solve for the modulated spectra of charged particles in the heliosphere. We demonstrate the accuracy and efficiency of our method through numerical experiments on a realistic model of the heliosphere

Control of colloidal CaCO3 suspension by using biodegradable polymers during fabrication

Fabrication of homogenous CaCO3 particles is a significant step in assembling polyelectrolyte capsules. It is crucial to control the dimensions, the shape and the charge of the calcium carbonate particles in order to have homogenously separated and charged templates as final result. For this reason, previously. hey have been deeply investigated. Recently, crystallization of CaCO3 was done by adding poly (sodium 4-styrenesulfonate) (PSS) as negatively charged polymer and poly (allylamine hydrochloride) (PAH) as positively charged polymer and the results were surprising. The homogenous particles were separated and they carried the same charge of the used polymer. The aim of this work was to investigate the synthesis process of CaCO3 particles in different experimental conditions: calcium carbonate was produced in presence and in absence of water and with addition of appropriate polymers. In particular, chitosan (CHI) and poly acrylic acid (PAA) were chosen as biodegradable polymers whereas PSS and PAH were chosen as non-biodegradable polymers. Shape and diameter of particles were investigated by using transmission and scanning electron microscopy, elemental composition was inferred by energy dispersive X-ray analyses whereas their charges were explored by using zeta potential