737 research outputs found
Special issue: Process safety in times of a pandemic
No full textGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Safety and Security Scienc
Un laboratorio per la xilografia italiana
No full textA partire dalle influenze internazionali presenti nei primi numeri della rivista "L'Eroica" di Ettore Cozzani si è esemplificata la posizione dello scrittore ed appassionato di xilografia attravero l'opera di due autori: Emilio Mantelli e Aldo Patocchi
Heat Radiation Effects
No full textEscalation triggered by fires resulting in domino scenarios was the cause of severe accidents in the process industry. As a matter of fact, the catastrophic failure of process equipment, both pressurized and atmospheric, may be induced by the heat-up due to the exposure to accidental fires, leading to the loss of containment of hazardous materials. In this chapter, the behavior of equipment exposed to accidental fire will be investigated in order to identify the fundamental mechanisms underlying the failure of vessels exposed to fire. In particular, both simplified tools and detailed models for the assessment of the performance of vessels involved in fires will be discussed. The final aim is to provide methods for the quantitative assessment of domino hazards caused by accidental fires, and for the application of both passive and active strategies for the control and reduction of the risk associated with incident escalation triggered by fire
Optimization of the economic and environmental profile of HCl removal in a municipal solid waste incinerator through historical data analysis
No full textIn order to comply with increasingly ambitious environmental regulations, the best available techniques for the abatement of several airborne pollutants are often based on multi-stage treatment processes. Treatment of hydrogen chloride (HCl), a typical fuel-related pollutant from the combustion of waste or biomass, is such a case. In the multi-stage configuration, while the overall required removal of pollutants is fixed, there are degrees of freedom in the repartition of the removal between stages, leaving room for process optimization. The present study offers an approach to the optimization of HCl removal, applied to a Municipal Solid Waste Incinerator (MSWI) equipped with a two-stage HCl abatement system based on the respective injection of hydrated lime and sodium bicarbonate. Historical plant data of the operation of the system for a reference year were collected and processed, in order to calibrate a semi-empirical model for the description of the two HCl treatment stages. The specific features of the two reactant systems, i.e. i) the temperature dependence of lime reactivity in the 1st stage and ii) the role of the bicarbonate cake on the fabric filter in the 2nd stage, were taken into account in the modelling. Process operation was then simulated by means of the calibrated and validated model, thus showing the advantage in terms of cost savings (-15 % annual operating costs) and avoided environmental impacts (-21 % annual generation of process residues) of operating the system at its optimum compared to the recorded process performance. The optimal repartition of removal between stages was found to depend on operating temperature and inlet HCl concentration. Copyright © 2018, AIDIC Servizi S.r.l
Deciduous dentition-anchored rapid maxillary expansion in crossbite and non-crossbite mixed dentition patients: reaction of the permanent first molar
No full textThis preliminary report describes our evaluation of the behavior of permanent maxillary first molars subsequent to rapid maxillary expansion (RME) in the mixed dentition in crossbite and non-crossbite cases; maxillary deciduous canines and second molars were used as anchorage. The RME appliance was cemented on the maxillary deciduous second molars and canines in 19 (13 females, six males) patients with unilateral or bilateral permanent molar crossbites (Group A) and in 13 (10 females, three males) patients who had no crossbites (Group B). After a mean appliance activation period of 15 days for 4-8 mm expansion, the appliance was stabilized and kept in place as retention for 5-10 months. Neither active nor passive retention was applied on first permanent molars. Impressions of dental arches were made before insertion of the appliance (T1), at stabilization (T2), and at debanding (T3). Dental measurements were registered at T1, T2, and T3. In Group A, the mean maxillary permanent intermo..
Indiscriminate Alignment in Cases with Severe Mandibular Crowding: How to Prevent and Manage an Everyday Orthodontic Problem
No full textSince untreated malocclusion can have a seriously detrimental effect on the quality of life,1 there has been an increasing demand for orthodontic treatment aimed at enhancing both the function and the esthetics of the entire stomatognathic system. In recent years, technological progress has enabled further advancements in the capacity of orthodontists to treat all types of malocclusions.2 Nevertheless, the subject of mistakes is almost never addressed. Few published articles highlight everyday clinical failures, even though they can be highly beneficial from an educational standpoint
Long-term evaluation of the molar movements following Pendulum and fixed appliances.
No full textTo describe the molar movements and skeletal changes associated with Pendulum-fixed appliance treatment and the long-term postretention period.The treatment sample consisted of 76 Class II patients, 35 males and 41 females. Lateral cephalograms were obtained at the start of treatment (T1); the end of distalization (T2); the end of orthodontic fixed appliance therapy (T3); and long-term observation (7 years 2 months later; T4). Mean age was 12 years 11 months at T1, 13 years 8 months at T2, 15 years 4 months at T3, and 22 years 5 months at T4. The average amount of Class II molar relationship was 3.1 mm, with a mean overjet of 5.9 mm at the beginning of treatment. A paired t-test was used to identify significant between-group differences between T2-T4 and T3-T4.Distal molar movement was obtained during the distalization phase (T2), and more than half of the distalizing effect was maintained at the end of maxillary growth (T4). Most of the relapse occurred during fixed appliance therapy (T3), whereas no significant change was detected in the postretention period (T4). The molar relationship did not show any significant difference between T2 and T4. The vertical facial dimension increased during the distalization phase (T2) and fixed appliance therapy (T3) but returned to the initial values during the postretention period (T4).The Pendulum appliance induces significant dentoalveolar effects, which can be partially maintained during the long-term period. The Class I molar relationship does not change during completion of individual growth. Increase in vertical facial dimension represents a temporary effect
Non-compliance maxillary molar distalizing appliances: an overview of the last decade.
No full textTo perform a literature review focusing on the use of non-compliance intraoral appliances for molar distalization therapy.A literature search ranged from January 1999 to December 2009 in order to describe dento-alveolar changes and skeletal vertical modifications following the use of conventional anchorage intraoral distalizing appliances. The quality of the retrieved studies was ranked on a 12-points scale, from low to high quality.A total of 214 articles were found and only 24 were considered eligible for the critical examination. Maxillary first molar distalization ranged from 6.4mm to 0.5mm with a concomitant distal tipping from 18.5° to bodily distalization. A smaller amount of distal movement and a greater amount of crown tipping can be noted at second molars. Premolar anchorage loss and incisor proclination represent an unavoidable side-effect and ranged from 4.33 mm to 0.73 mm and from 13.7° to 0.6° respectively. Skeletal vertical modifications were noted. Increase in vertical facial dimension ranged from 1.5° to -1.8° and lower anterior facial height ranged from an increase of 3.2 to a decrease of 0.6 mm. The assessment of study quality showed that 19 studies were of low quality, 3 of medium quality and 2 of medium-high quality.Maxillary molar distalization can be effectively performed with the use of noncompliance intraoral appliances. As a consequence, premolar anchorage loss, incisor proclination and a slight increase in vertical facial dimension can occur. Because of the lack of high-quality studies the findings of this review should be carefully interpreted
L’analisi di vulnerabilità e la valutazione dell’effetto domino
No full textL'analisi di vulnerabilità è una fase necessaria nella valutazione del rischio in impianti di processo. La valutazione delle conseguenze dei rilasci incidentali, infatti, fornisce un insieme di dati fisici relativi agli scenari incidentali (mappe di irraggiamento da incendio, sovrappressione, concentrazioni tossiche, etc.), sulla base dei quali è necessario valutare l'effetto ultimo dell'evento incidentale su un insieme di recettori: la popolazione (intesa in senso vasto, quindi comprendendo anche i lavoratori), l'ambiente e gli elementi strutturali dell'impianto. La trasformazione dei valori calcolati degli effetti fisici in una valutazione quantitativa del danno ultimo subito dai recettori è detta analisi di vulnerabilità. L'analisi della vulnerabilità dei diversi recettori rispetto agli effetti fisici degli scenari incidentali è quindi un presupposto fondamentale per valutare la severità (o magnitudo) di un incidente, indipendentemente dal fatto che l'analisi sia indirizzata alla valutazione quantitativa di indici di rischio o a valutazioni semplificate basate, ad esempio, su matrici di compatibilità.
L'analisi della vulnerabilità degli elementi strutturali dell'impianto, oltre a fornire dati sulla "asset integrity" attesa in funzione degli scenari incidentali possibili, è anche il presupposto per analizzare la possibilità di effetto domino, ovvero della propagazione ed amplificazione di eventi incidentali causati dal danneggiamento strutturale di elementi di impianto causati dall'incidente primario.
In quanto segue sono descritte le principali metodologie disponibili per l'analisi di vulnerabilità della popolazione e un approccio all'analisi quantitativa dell'effetto domino
Screening Methodologies for Genetic Modified Organisms (GMOs)
No full textDescription of the bioanalytical approaches of GMOs detectio
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