Optimized powerplant configurations for improved rotorcraft operational performance

This paper presents an integrated multidisciplinary rotorcraft design and optimization framework, deployed for the design and assessment of a conceptual rotorcraft powerplant configuration at mission level. The proposed approach comprises a wide-range of individual modeling theories applicable to rotorcraft flight dynamics, gas turbine engine performance and weight estimation as well as a novel physics-based, stirred reactor model for the rapid estimation of gas turbine gaseous emissions. A novel Single-Objective and Multi-Objective Particle Swarm Optimizer is coupled with the aforementioned integrated rotorcraft multidisciplinary design framework. The combined approach is applied to the multidisciplinary design and optimization of a reference Twin Engine Light civil rotorcraft modeled after the Eurocopter Bo105 helicopter, operating on representative mission scenario. Through the application of Single-Objective optimization, optimum engine design configurations are acquired in terms of mission fuel consumption, engine weight and gaseous emissions at constant technology level. Multi-Objective studies are carried out in order to quantify the optimum interrelationship between mission fuel consumption and gaseous emissions for the representative Twin Engine Light rotorcraft operation and a variety of engine configurations. The proposed approach essentially constitutes an enabler in terms of focusing the multidisciplinary design of rotorcraft powerplants to realistic, three-dimensional operations and towards the realization of associated engine design tradeoffs at mission level

Multi-objective optimization of a regenerative rotorcraft powerplant: quantification of overall engine weight and fuel economy

A computationally efficient and cost effective simulation framework has been implemented to perform design space exploration and multi-objective optimization for an advanced regenerative rotorcraft powerplant configuration at mission level. The proposed framework is developed by coupling a comprehensive rotorcraft mission analysis code with a design space exploration and optimization package. The overall approach is deployed to design and optimize the powerplant of a reference twin-engine light rotorcraft, modelled after the Bo105 helicopter, manufactured by Airbus Helicopters. Firstly, a sensitivity analysis of the regenerative engine is carried out to quantify the interrelationship between the engine thermodynamic cycle design parameters, engine weight, and overall mission fuel economy. Secondly, through the execution of a multi-objective optimization strategy, a Pareto front surface is constructed, quantifying the optimum trade-off between the fuel economy offered by a regenerative engine and the associated weight penalty. The optimum sets of cycle design parameters obtained from the structured Pareto front suggest that the employed heat exchanger effectiveness is the key design parameter affecting the engine weight and fuel efficiency. Furthermore, through quantification of the benefits suggested by the acquired Pareto front, it is shown that, the fuel economy offered by the simple cycle rotorcraft engine can be substantially improved with the implementation of regeneration technology, without degrading the payload-range and airworthiness (One- Engine-Inoperative) requirements of the rotorcraft

Sustainable intensification? Increased production diminishes omega-3 content of sheep milk

Intensifying agricultural production alters food composition, but this is often ignored when assessing system sustainability, yet it could compromise consumers’ health and the concept of ‘sustainable diets’. Here we consider milk composition from Mediterranean dairy sheep, finding inferior fatty acid (FA) profiles with respect to consumer health as a result of a more intensive system of production. Semi-intensive management did produce 57% more milk per ewe with 20% lower fat content, but inferior fat composition. Milk had a nutritionally poorer fatty acid (FA) profile, with 18% less omega-3 FA (n-3) (19% less long-chain n-3) and 7% less monounsaturated FA but 3% more saturated FA (9% higher in C14:0) concentrations compared with ewes under traditional, extensive management. Redundancy analysis identified close associations between fat composition and animal diets, particularly concentrate supplementation and grazing cultivated pasture - n-3 was associated with grazing diverse, native mountain pastures. The paper questions if identifying such key elements in traditional systems could be deployed for ‘sustainable intensification’ to maintain food quality whilst increasing output

Wittgenstein και θρησκευτική πίστη: όψεις της θρησκευτικής γλώσσας

Στην παρούσα εργασία επιχειρείται μία σε καμμία περίπτωση εξαντλητική της ολότητας των ρητά ανιχνεύσιμων ή έστω και απλώς δυνητικά ερμηνεύσιμων ως τέτοιων εκφάνσεων της διαπραγμάτευσης του φαινομένου της θρησκευτικής γλώσσας αλλά και της διαλογικής εκτύλιξης της θρησκευτικής πίστης ως μίας ιδιαίτερης μορφής παραγωγής (ή αποκάλυψης) νοήματος ανασύσταση της επιχειρηματολογίας του Wittgenstein όπως αυτή άμεσα ή έμμεσα πραγματώνεται στην όψιμη σκέψη του και ιδίως στις 'Διαλέξεις πάνω στην θρησκευτική πίστη'. Επιπροσθέτως, καταβάλλεται προσπάθεια, μέσω της ανασύστασης των επιφωτιζόμενων από τον Wittgenstein όψεων της θρησκευτικής γλώσσας, να αναδειχθούν τόσο οι εγγενείς ιδιαιτερότητες που χαρακτηρίζουν τον στοχασμός του επί της θρησκευτικότητας όσο και η πιθανή προβληματικότητα των ορίων που εκείνος θέτει σε αυτήν.In this paper, an attempt is made towards a -by no means exhaustive of the totality of the explicitly detectable or even just potentially interpretable as such manifestations of the elaboration of the phenomenon of religious language as well as that of the interlocutory unfolding of religious faith as a particular form of producing (or revealing) meaning- reconstitution of Wittgenstein's argumentation as it is directly or indirectly carried out in his later period and especially in the 'Lectures on religious belief'. In addition, an effort is made, through the reconstruction of the aspects of religious language illuminated by Wittgenstein, to highlight both the inherent peculiarities that characterize his reflection on religiosity and the possibly problematic nature of the limits he sets on it

Optimized consumer-centric demand response

Demand side management has focused more on centralized control and heavily depends on continuous consumer interaction, often overlooking consumer thermal and visual comfort. Distribution grid management will necessitate the active involvement of new market actors (i.e. prosumers, aggregators, distribution system operators, retailers, etc.), so a holistic approach becomes critical to transform demand into an active element of electricity system management. This paper presents a consumer centric demand flexibility framework, which facilitates the automated, human-centric demand response, minimizes consumer interactions and accommodates various power system ancillary services

The large-scale environment of thermonuclear and core-collapse supernovae

The new generation of wide-field time-domain surveys has made it feasible to study the clustering of supernova (SN) host galaxies in the large-scale structure (LSS) for the first time. We investigate the LSS environment of SN populations, using 106 dark matter density realisations with a resolution of ∼3.8 Mpc, constrained by the 2M+ + galaxy survey. We limit our analysis to redshift z < 0.036, using samples of 498 thermonuclear and 782 core-collapse SNe from the Zwicky Transient Facility’s Bright Transient Survey and Census of the Local Universe catalogues. We detect clustering of SNe with high significance; the observed clustering of the two SNe populations is consistent with each other. Further, the clustering of SN hosts is consistent with that of the Sloan Digital Sky Survey (SDSS) Baryon Oscillation Spectroscopic Survey DR12 spectroscopic galaxy sample in the same redshift range. Using a tidal shear classifier, we classify the LSS into voids, sheets, filaments, and knots. We find that both SNe and SDSS galaxies are predominantly found in sheets and filaments. SNe are significantly under-represented in voids and over-represented in knots compared to the volume fraction in these structures. This work opens the potential for using forthcoming wide-field deep SN surveys as a complementary LSS probe

SN2019wxt: An ultrastripped supernova candidate discovered in the electromagnetic follow-up of a gravitational wave trigger

We present optical, radio, and X-ray observations of a rapidly evolving transient SN2019wxt (PS19hgw), discovered during the search for an electromagnetic counterpart to the gravitational-wave (GW) trigger S191213g. Although S191213g was not confirmed as a significant GW event in the off-line analysis of LIGO-Virgo data, SN2019wxt remained an interesting transient due to its peculiar nature. The optical/near-infrared (NIR) light curve of SN2019wxt displayed a double-peaked structure evolving rapidly in a manner analogous to currently known ultrastripped supernovae (USSNe) candidates. This double-peaked structure suggests the presence of an extended envelope around the progenitor, best modeled with two components: (i) early-time shock-cooling emission and (ii) late-time radioactive 56Ni decay. We constrain the ejecta mass of SN2019wxt at Mej ≈ 0.20M⊙, which indicates a significantly stripped progenitor that was possibly in a binary system. We also followed up SN2019wxt with long-term Chandra and Jansky Very Large Array observations spanning ∼260 days. We detected no definitive counterparts at the location of SN2019wxt in these long-term X-ray and radio observational campaigns. We establish the X-ray upper limit at 9.93 × 10−17 erg cm−2 s−1 and detect an excess radio emission from the region of SN2019wxt. However, there is little evidence for SN1993J- or GW170817-like variability of the radio flux over the course of our observations. A substantial host-galaxy contribution to the measured radio flux is likely. The discovery and early-time peak capture of SN2019wxt in optical/NIR observations during EMGW follow-up observations highlight the need for dedicated early, multiband photometric observations to identify USSNe