Design and Experimentation of a Premixed Rotating Detonation Engine

Desire for a more efficient air breathing engine has shifted research attention to the Rotating Detonation Engine (RDE). Detonation is a more efficient combustion process than deflagration and provides a pressure gain. The RDE detonation cycle occurs in a compact volume to produce a high specific impulse engine. Computational fluid dynamic (CFD) models have predicted higher specific impulse and detonation wave speeds than has been seen in experimental RDE. The CFD models frequently assume premixed reactants and ignore inlet geometries to facilitate rapid computation. An experimental premixed RDE was sought to test if the premixed assumption in CFD was the root cause of the discrepancy between computational and experimental results. Design of a successful premixed RDE employed a feed system that simultaneously arrested flashback into the premixture while it fed the detonation. Flashback arresting feed designs were explored with single injector tests and validated with a fully premixed RDE. A relationship between arresting length and detonation feed requirements was derived and used to design a premixed RDE that fed premixture through feed slots that were 2.5 cm long and 0.5 mm high and operated on ethylene fuel and air oxidizer. The premixed RDE operated within a narrower region of equivalence ratio than a non-premixed RDE. Chemiluminescence video indicated that the premixed RDE experience combustion reactant-product mixing, and supports the theory that mixing delays are the root cause of slower wave speeds in experimental RDE. Time averaged chemiluminescence results indicate that RDE detonations to not complete the reaction within the detonation wave, and suggest that future CFD studies should assume unmixed reactants, model the full injection geometry, and include a comprehensive chemical mechanism

Comparative Analysis of a High Bypass Turbofan using a Pulsed Detonation Combustor

It has been proposed that the implementation of a pulsed detonation combustor in a high-bypass turbofan engine would result in an engine that is both more efficient and more reliable. The validity of the performance claims are evaluated based on a comparison between the baseline and hybrid turbofans. The hybrid pulsed detonation engine was modeled in the Numerical Propulsion Simulation System (NPSS) and shares a common architecture with the baseline turbofan model, except that the combustor of the baseline engine is replaced with a pulsed detonation combustor. Detonation effects are calculated using a closed form solution of the Chapman-Jouguet Mach number with a total energy correction applied. Cycle time is calculated to provide a reasonable estimate of frequency for the user input geometry, and the losses due unsteady flow are accounted for by applying pressure and temperature losses to the fluid. A parametric study was performed to evaluate the effects of these losses on net thrust and TSFC. There is a definite level of acceptable loss that if surpassed makes pulsed detonation combustion a good candidate for inclusion into a hybrid turbofan engine

Simulating the Impact on the Local Economy of Alternative Management Scenarios for Natural Areas

This working paper estimates the impact on the local economy of the High Garda Natural Park of alternative management scenarios for the West Garda Regional Forest. The local economy is specialized in tourist services and strongly linked to the tourist presence and their level of expenditure. We wish to investigate the effects of the participative management strategy, which takes into account users preferences and the non-participative strategy, using the SAM multiplier analysis. The local SAM has been constructed considering three sectors: agriculture, tourism and a third aggregate sector including all the other activities. The resident population has been divided into two categories: residents employed in the tourist sector and the remaining resident population. The SAM analysis shows that the accounting representation of the local economy is meaningful and that the participative program, if chosen by the central regional management, would be the most desirable program also at the local level.Tourism, SAM, Multiplier analysis

Relazione tecnica sulle attività della campagna oceanografica “Ancheva 2017”

La presente relazione tecnica descrive le attività svolte nella Campagna oceanografica “Ancheva 2017”, tra il 23 luglio ed il 7 agosto 2017, a bordo della N/O “G. Dallaporta”. Gli echosurvey acquisiti hanno permesso di valutare la biomassa e la distribuzione spaziale dei piccoli pelagici nella piattaforma meridionale della Sicilia, da Marsala a oltre Capo Passero, e nella piattaforma Maltese (GSA 16, FAO sub area 37.2.2). Parallelamente alle suddette attività sono state svolti il campionamento biologico (di piccoli pelagici) con rete pelagica (volante monobarca), il campionamento di tessuti di pesci pelagici (gonadi, fegato e sangue), il campionamento di acqua (per la misurazione dei parametri fisico-chimici della colonna d’acqua e per l’analisi di Nutrienti ed Isotopi di azoto e carbonio) ed, infine, il campionamento ittioplantonico (per le analisi degli aminoacidi sulle larve di Engraulis encrasicolus)

Evaluation of expressive writing for postpartum health: A randomized controlled trial

Pregnancy, birth and adjusting to a new baby is a potentially stressful time that can negatively affect the health of women. There is some evidence that expressive writing can have positive effects on psychological and physical health, particularly during stressful periods. The current study aimed to evaluate whether expressive writing would improve women’s postpartum health. A randomized controlled trial was conducted with three conditions: expressive writing (n=188), a control writing task (n=213), or normal care (n=163). Measures of psychological health, physical health and quality of life were measured at baseline (6-12 weeks postpartum), 1 month and 6 months later. Ratings of stress were taken before and after the expressive writing task. Intent-to-treat analyses showed no significant differences between women in the expressive writing, control writing and normal care groups on measures of physical health, anxiety, depression, mood or quality of life at 1 and 6 months. Uptake and adherence to the writing tasks was low. However, women in the expressive writing group rated their stress as significantly reduced after completing the task. Cost analysis suggest women who did expressive writing had the lowest costs in terms of healthcare service use and lowest cost per unit of improvement in quality of life. Results suggest expressive writing is not effective as a universal intervention for all women 6-12 weeks postpartum. Future research should examine expressive writing as a targeted intervention for women in high-risk groups, such as those with mild or moderate depression, and further examine cost-effectiveness

Maternal posttraumatic stress disorder during the perinatal period and child outcomes: A systematic review

BACKGROUND: Approximately 3.3% of women in pregnancy have posttraumatic stress disorder (PTSD) and 4% of women postpartum PTSD. The impact of maternal PTSD during the perinatal period (from conception until one year postpartum) on child outcomes has not been systematically examined. METHOD: A systematic review was conducted to synthesize and critically evaluate quantitative research investigating the association between perinatal PTSD and child outcomes. Databases EMBASE, BNI, Medline, PsycInfo and CINAHL were searched using specific inclusion and exclusion criteria. RESULTS: 26 papers reporting 21 studies were identified that examined associations between perinatal PTSD and postpartum birth outcomes, child development, and mother-infant relationship. Studies reviewed were heterogeneous, with poor-to-medium scores of methodological quality. Results showed that maternal postpartum PTSD is associated with low birth weight and lower rates of breastfeeding. Evidence for an association between maternal PTSD and preterm birth, fetal growth, head circumference, mother-infant interaction, the mother-infant relationship or child development is contradictory. Associations between maternal PTSD and infant salivary cortisol levels, and eating/sleeping difficulties are based on single studies, so require replication. LIMITATIONS: Methodological weaknesses of the studies included insufficient sample size, use of invalidated measures, and limited external validity. CONCLUSION: Findings suggest that perinatal PTSD is linked with some negative child outcomes. Early screening for PTSD during the perinatal period may be advisable and onward referral for effective treatment, if appropriate. Future research using larger sample sizes, validated and reliable clinical interviews to assess PTSD, and validated measures to assess a range of child outcomes, is needed

RAPPORTO SULLE INDAGINI DI SISMICA A RIFLESSIONE, GRAVIMETRICHE, MAGNETOMETRICHE, MORFOBATIMETRICHE E CAMPIONAMENTO FONDO MARE NELL’ ARCO CALABRO (MAR IONIO) CAMPAGNA CALAMARE08

The study of the Calabrian Arc in the Ionian Sea is key to understanding of the geological processes in the Mediterranean Sea. We present the technical details and results of cruise CALAMARE08 with N/O Urania during spring 2008. We acquired a large set of geological and geophysical data, among them Multichannels Seismic and SBP, magnetometry, gravimetry, swath bathymetry and coring of sea bottom