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Cyclones are employed in many waste treatment industries for the dust collection or abatement purposes. The prediction of the dust collection efficiency is crucial for the design and optimization of the cyclone. However, this is a difficult task because of the complex physical phenomena that influence the removal of particles. Aim of the paper is to present two new meta-models for the prediction of the collection efficiency curve of cyclone separators. A Backpropagation Neural Network (BPNN) and Support Vector Regression (SVR) models were developed using Python environment. These were trained with a set of experimental data taken from the literature. The prediction capabilities of the models were first assessed by comparing the estimated collection efficiency for several cyclones against the corresponding experimental data. Second, by comparing the collection efficiency curves predicted by the models and those obtained from classic models available in the literature for the cyclones included in the validation dataset. The BPNN demonstrated better predictive capability than the SVR, with an overall mean squared error of 0.007 compared to 0.015, respectively. Most important, a 40% to 90% accuracy improvement of the literature models predictions was achieved. [ABSTRACT FROM AUTHOR]

The basic RANS-CFD analysis of the simplest radial-inflow turbine configuration is the subject of this paper. An original technique is here proposed to model the effect of the vaneless spiral casing using single-channel CFD calculations and providing an effective alternative to the more complex simulation of the 360-degree domain otherwise required to simulate this turbine configuration. The aim of the paper is to verify the effectiveness of the proposed modelling technique as a reliable engineering approach conceived to support the preliminary design phase of radial-inflow turbines with time-effective CFD calculations. To this end, the open-source CFD code MULTALL has been used to predict the aerodynamic performance of optimal designs of radial-inflow turbines with different specific speed and diameter and working with air as ideal gas. The MULTALL predictions are compared with the corresponding steady-state results obtained by calculations suited to the preliminary assessment of radial turbines designs performed on fully 360-degree turbine domains using the commercial code Star CCM+®. The investigation is conducted on two turbines that are designed in accordance with a widely validated method. The results show that the proposed CFD approach predicts well the trends and values of the aerodynamic performance of both the turbine designs: a 5% overestimation of the performance predicted by the fully 360-degree CFD models was never exceeded. The suggested turbine modelling approach implemented in MULTALL requires a three times lower computation time than the corresponding traditional 360-degree model.

The paper deals with the optimisation of the charging efficiency in a small two-stroke high-speed engine according to well-established design guidelines. The aim is to present the method successfully used in the preliminary screening of the performance improvement attainable in a crank-case-compression engine by design modifications to the transfer ports and manifolds. The method applies a basic CFD model of the steady-state flow across the cylinder block validated against experimental tests at the discharge flow bench. This model is used to approximate the actual scavenging process through a transient simulation of the cold flow across the cylinder inside which the piston is fixed at the bottom centre. A fast assessment of the charging efficiency is permitted by a transported passive scalar implemented in the model to easily estimate all the parameters needed for monitoring the effectiveness of the scavenging process at each crankangle. This practical design approach has been applied to the geometry of a Schnürle-type loop-scavenged 125cc single-cylinder engine compliant with the 2018 FIA homologation form for the KF2 karting competition category. The maximum increase of indicated mean effective pressure expected according to the comparison between the CFD simulations of the original and the modified design of the transfer ports is approximately equal to 4%. This result demonstrates that the CFD analyses are sensitive to the limited modifications commonly needed to tune two-stroke racing-engines and confirms that the suggested design approach can be profitably employed by engineers and technicians involved in the design of small two-stroke highspeed engines.

Abstract Background Atopic dermatitis (AD) is often the prelude to allergic diseases. The aim of this study was 1) to evaluate if an integrated management regime could bring about a change in the evolution of the disease in comparison to the results of a previous study; 2) to determine whether the refinement of allergic investigations allowed to identify more promptly the risk factors of evolution into respiratory allergic diseases. Methods The study included 176 children affected by AD and previously evaluated between 1993 and 2002 at the age of 9-16 months, who underwent a telephonic interview by means of a semi-structured, pre-formed questionnaire after a mean follow-up time of 8 years. According to the SCORAD, at first evaluation children had mild AD in 23% of cases, moderate in 62%, severe in 15%. Results AD disappeared in 92 cases (52%), asthma appeared in 30 (17%) and rhinoconjunctivitis in 48 (27%). The factors significantly related to the appearance of asthma were: sensitization to food allergens with sIgE > 2 KU/L (cow's milk and hen's egg; P < 0.05); to inhalant allergens with sIgE > 0.35 KU/L (P < 0.05). Logistic regression analysis showed that inhalant sensitization was positively related to the occurrence of asthma (OR = 4.219). While AD showed similar rates of disappearance to those of our previous study, the incidence of asthma was reduced, at the same follow-up time, from 29% to 15% (P = 0.002), and the incidence of rhinoconjunctivitis from 35% to 24% (P = 0.02). Conclusion Comparing the results with those of the previous study, integrated management of AD does not seem to influence its natural course. Nevertheless, the decrease in the percentage of children evolving towards respiratory allergic disease stresses the importance of early diagnosis and improvement management carried out by specialist centers. The presence of allergic sensitization at one year of age might predict the development of respiratory allergy.

Abstract Background Early highly active antiretroviral therapy (HAART), started within the first months of age, has been proven to be the optimal strategy to prevent immunological and clinical deterioration in perinatally HIV-infected children. Nevertheless, data about long-term follow-up of early treated children are lacking. Methods We report data from 40 perinatally HIV-infected-children receiving early HAART, with a median follow-up period of 5.96 years (interquartile range [IQR]:4.21–7.62). Children were enrolled at birth in the Italian Register for HIV Infection in Children. Comparison with 91 infected children born in the same period, followed-up from birth, and receiving deferred treatment was also provided. Results Nineteen children (47.5%) were still receiving their first HAART regimen at last follow-up. In the remaining children the first regimen was discontinued, after a median period of 3.77 years (IQR: 1.71–5.71) because of viral failure (8 cases), liver toxicity (1 case), structured therapy interruption (3 cases), or simplification/switch to a PI-sparing regimen (9 cases). Thirty-nine (97.5%) children showed CD4+ T-lymphocyte values>25%, and undetectable viral load was reached in 31 (77.5%) children at last visit. Early treated children displayed significantly lower viral load than not-early treated children, until 6 years of age, and higher median CD4+ T-lymphocyte percentages until 4 years of age. Twenty-seven (29.7%) not-early treated vs. 0/40 early treated children were in clinical category C at last follow-up (P < 0.0001). Conclusion Our findings suggest that clinical, virologic and immunological advantages from early-HAART are long-lasting. Recommendations indicating the long-term management of early treated children are needed.

Abstract Background Asthma is a serious global health problem and its prevalence is increasing, especially among children. It represents a significant social and economic burden, and it can severely affect the health-related quality of life (HRQL) of patients. Among the numerous questionnaires aiming at evaluating asthma HRQL in children, the Pediatric Asthma Quality of Life Questionnaire (PAQLQ) has proved to have good measurement properties. The present study was aimed at investigating the possible role of the Italian, self-administered version of the PAQLQ in the routine clinical evaluation of children affected by bronchial asthma. Methods 52 Italian children and adolescents (40 males and 12 females), aged 6 to 17 years, affected by allergic asthma, were enrolled. Each patient was evaluated twice, and at each visit asthma control and severity were assessed, spirometry was performed and the patients completed the self-administered version of the PAQLQ. Results The questionnaire was well-accepted and understood by the children. Children showed an overall good quality of life, with mild impairment in the activity and emotional function domains. The PAQLQ showed an overall good correlation with the clinical and functional indexes that are normally evaluated in follow-up visits of asthmatic patients. The PAQLQ appeared to be strongly related to asthma control, both at the first (p < 0.01) and second (p < 0.001) time of the study. The PAQLQ was also seen to decrease with increasing asthma severity. The results suggest a better compliance of the children towards completion of the questionnaire at t1. Finally, the PAQLQ does not appear to discriminate HRQL in patients with good lung function. Conclusion The Italian version of the PAQLQ is a quick-to-administer aid to clinical activity and can add valuable information to symptom reports, objective measurements and clinical assessment of asthma control and severity in daily clinical practice. Re-administration at each follow-up visit allows HRQL to be monitored over time.

Discusses a case of infantile acute hemorrhagic edema in a child with von Willebrand's disease. Case background; Tender symmetric edematous and target-like purpura; Etiology.