Monitoring a PGD solver for parametric power flow problems with goal-oriented error assessment

This is the peer reviewed version of the following article: [García-Blanco, R., Borzacchiello, D., Chinesta, F., and Diez, P. (2017) Monitoring a PGD solver for parametric power flow problems with goal-oriented error assessment. Int. J. Numer. Meth. Engng, 111: 529–552. doi: 10.1002/nme.5470], which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/nme.5470/full. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.The parametric analysis of electric grids requires carrying out a large number of Power Flow computations. The different parameters describe loading conditions and grid properties. In this framework, the Proper Generalized Decomposition (PGD) provides a numerical solution explicitly accounting for the parametric dependence. Once the PGD solution is available, exploring the multidimensional parametric space is computationally inexpensive. The aim of this paper is to provide tools to monitor the error associated with this significant computational gain and to guarantee the quality of the PGD solution. In this case, the PGD algorithm consists in three nested loops that correspond to 1) iterating algebraic solver, 2) number of terms in the separable greedy expansion and 3) the alternated directions for each term. In the proposed approach, the three loops are controlled by stopping criteria based on residual goal-oriented error estimates. This allows one for using only the computational resources necessary to achieve the accuracy prescribed by the end- user. The paper discusses how to compute the goal-oriented error estimates. This requires linearizing the error equation and the Quantity of Interest to derive an efficient error representation based on an adjoint problem. The efficiency of the proposed approach is demonstrated on benchmark problems.Peer ReviewedPostprint (author's final draft

Testing creation of matter with neutrinoless double beta decay

In this brief review, the importance of the so called neutrinoless double beta decay transition in the search for physics beyond the Standard Model is emphasized. The expectations for the transition rate are examined in the assumption that ordinary neutrinos have Majorana masses. We stress the relevance of cosmological measurements and discuss the uncertainties implied by nuclear physics.Comment: 9 pages. Based on the review paper Neutrinoless double beta decay: 2015 review, Adv.High Energy Phys. 2016 (2016) 2162659. To appear in the proceedings of the XVII International Workshop on Neutrino Telescopes 13-17 March 2017, Venice, Ital

Bark harvesting: a potential threat for the Grandidier’s baobab Adansonia grandidieri in western Madagascar

The Grandidier’s baobab conveys the image of Madagascar worldwide. Locally, these trees have multiple uses; all parts of the plant are exploited by the population. We investigated the patterns of bark harvesting on the Grandidier’s baobab in three districts in the Menabe Region: Mahabo, Manja and Morondava. Following 103 transects of 1km each, we found that 54.0% of the baobab trees had been subject to bark extraction. The mean total area exploited per tree was 3.1 ± 0.2m2. Between April 2013 and January 2014, we also monitored four markets that regularly sell baobab products: Bemanonga, Mahabo, Morondava and Analaiva. Bemanonga revealed to be the largest market for the baobab bark with 21,594 straps and 34,517m of ropes recorded during the observation period. We estimate that some 9800 Grandidier’s baobab trees have been affected by debarking to supply the demands recorded over the ten months monitoring period. If this demand remains constant, all baobab trees in Menabe would be debarked within the next 39 years. Since most baobab trees have been located in hard-to-reach areas and in protected areas, bark extraction may intensify in accessible sites and populations without protected status may disappear locally. This would result in local extinction of the species within a short period. To ensure sustainable management of the Grandidier’s baobab, we recommend enriching the population by planting young baobabs, regulating access to the resources through local management structures and promoting alternatives to baobab ropes. RésuméLe baobab de Grandidier est une espèce emblématique de Madagascar. Il évoque la Grande Île dans le monde entier. Dans sa zone d’occurrence, c’est une espèce à usage multiple pour les riverains qui utilisent toutes les parties de ce baobab. La présente étude porte sur l’exploitation de l’écorce du baobab de Grandidier dans la région Menabe, plus particulièrement dans les districts de Mahabo, Manja et de Morondava. Pour estimer l’étendue de l’exploitation des écorces sur les pieds de baobabs, des observations ont été réalisées sur 103 transects de 1 km de long entre avril 2013 et janvier 2014. Pour évaluer l’importance des écorces de baobab pour les riverains, des observations ont été conduites au niveau de quatre marchés de la région dans les villes de Bemanonga, Mahabo, Morondava et Analaiva au cours de la même période. Au total, 21 594 lanières d’écorce et 34 517 m de corde de baobab ont été recensés dans les quatre marchés. La plus importante quantité d’écorce de baobabs commercialisée a été enregistrée à Bemanonga. À partir des données récoltées, il est estimé que près de 9800 pieds de baobabs à écorcer sont nécessaires pour couvrir les besoins des riverains pendant la seule période d’études de 10 mois. Si la demande devait se maintenir à ce niveau, tous les pieds de baobab de la région Menabe, dont la population avait été estimée à environ un million d’individus, seraient écorcés au cours des 39 prochaines années. Comme la plupart des pieds de baobab ont été localisés dans des zones difficiles d’accès et dans les aires protégées, l’extraction des écorces pourrait s’intensifier dans les sites accessibles et les populations qui ne bénéficient d’aucun statut de protection pourraient disparaître localement. Pour assurer la gestion durable du baobab de Grandidier, il est ainsi recommandé de renforcer la population existante par la plantation de jeunes plants, la régulation de l’accès aux ressources par des structures locales de gestion et la promotion d’alternatives aux cordes réalisées avec les écorces de baobab

Rabbit neutering in primary-care education: insights from a surgical clinic

Involvement in canine and feline surgical neutering clinics is generally considered to be a key element of primary-care veterinary education, yet opportunities for veterinary students to develop their surgical skills with rabbit patients are uncommon. This is despite the fact that rabbits are currently estimated to be the third-most popular companion animal species and the fact that the British Small Animal Veterinary Association (BSAVA) recommends that all non-breeding rabbits be neutered soon after they attain sexual maturity. We describe a pilot rabbit-neutering clinic designed to provide high-quality care for rabbit patients while offering opportunities for undergraduate surgical and case-management skills development. We report on the clinical outcomes for patients. Rates of morbidity (n=18) and mortality (n=1) were low. Of complications reported, the majority (n=16) were considered minor. Challenges included ensuring that staff and students were trained in the specific features of rabbit anesthesia and recovery behavior. We conclude that rabbit surgical clinics offer excellent learning opportunities for undergraduate veterinary students. With prior training in handling and close individual supervision, it is possible to achieve good clinical outcomes and to have a positive impact on the welfare of companion animal populations

design and off design analysis of an orc coupled with a micro gas turbine

Abstract In the recent years, the possibility of recovering heat from gas turbine (GT) exhaust gases using Organic Rankine Cycles (ORC) have been largely explored. However, it is difficult to identify working fluids properly matching with micro-GT exhaust gases. For this reason, in the present work, the fluid selection and the plant layout optimization of an ORC which recovers the exhaust gases heat content of a 65 kW micro-gas turbine is presented. During the optimization process different plant configurations are considered: simple or regenerative and subcritical or transcritical. Exergy and economic analyses are also performed to estimate the exergy destruction rate and evaluate the economic feasibility of the optimized solutions. In order to find out the most suitable ORC unit and its behaviour, an off-design analysis is also performed using the commercial software Aspen Plus. Adopting a management strategy that maintains the turbine inlet temperature constant the best off-design performance is reached with Cyclopentane as working fluid

Design and management of an Integrated Thermal Energy Storage System

openNowadays our society is experiencing an energy transition, in which renewable energy sources are assuming a newer and more central role in the energetic mix. In these scenarios, to boost the decarbonization and the usage of sustainable energy systems, Thermal Energy Storage Systems will play a fundamental role. In fact, given the discontinuous and intermittent behaviour of renewable sources, storage devices allow the mitigation of these effects and the enhancement of the electrical grid. These devices can find room not only for electrical applications, but even in the residential and industrial sectors. In this Master's thesis, the scope is to individuate how it is possible to size and manage, in an optimum way, Thermal Energy Storage Systems, starting from the production curves of a renewable energy sources power plantNowadays our society is experiencing an energy transition, in which renewable energy sources are assuming a newer and more central role in the energetic mix. In these scenarios, to boost the decarbonization and the usage of sustainable energy systems, Thermal Energy Storage Systems will play a fundamental role. In fact, given the discontinuous and intermittent behaviour of renewable sources, storage devices allow the mitigation of these effects and the enhancement of the electrical grid. These devices can find room not only for electrical applications, but even in the residential and industrial sectors. In this Master's thesis, the scope is to individuate how it is possible to size and manage, in an optimum way, Thermal Energy Storage Systems, starting from the production curves of a renewable energy sources power plan

Biogas Engine Emissions: Standards and On-Site Measurements

Abstract The European Union, with 60% of the total global production of biogas, is the world leader. In 2012, the percentage of electrical energy produced by biogas was 6% of the EU-28 electricity generated through renewable sources while, in 2013, the almost 830 biogas units produced 7448 GWh which corresponds to 14% of EU-28 gross electricity production. Germany, U.K. and Italy are the main EU biogas producers with over 78% of the 2013 primary energy production. Electricity production is the main biogas energy recovery form because the engine cooling water is used to maintain the digester required temperature while energy crops and manure are the most used organic matters. Spark-ignition engines with a rated power of 1MWel in which the filtered biogas is burned to produce work is the widely-adopted technology. With the aim of analyzing the emissions of a real biogas engine, in the present work, the authors firstly present an overview of the Italian biogas sector and the most used conversion technologies. Then, the standards which regulate the biogas plant emissions and the emissions data acquired during a one-year monitoring activity on 10 biogas plants are presented and discussed with the aim of assessing the biogas units' real emissions

Sources of Sex Information Used by Young British Women Who Have Sex with Women (WSW) and Women Who Have Sex Exclusively with Men (WSEM): Evidence from the National Survey of Sexual Attitudes and Lifestyles

There is little consideration about the provision of information about sex to women who have sex with women (WSW). This study drew on data from the third National Survey of Sexual Attitudes and Lifestyle, a nationally representative survey of people in Great Britain. Logistic regression was undertaken to examine firstly the relationships between WSW and women who have sex exclusively with men (WSEM) and their main source of information about sex, and secondly between WSW/WSEM and unmet need for information about sex. Each source was included as the binary outcome indicating yes this was the main source, or no this was not the main source of information about sex. The results found that WSW had significantly lower odds of reporting lessons at schools as their main source of information, and significantly higher odds of reporting sources defined as ‘other’ (predominantly first girlfriend/boyfriend or sexual partner) as their main source of information. Reported levels of unmet need for information was also higher amongst young WSW compared with WSEM. This study provides new insights into the sex educational needs of young women and highlights the need for sex education in schools in Great Britain to include information on a full-range of sexual practices, including same-sex sexual relationships

Waste heat recovery technologies for offshore platforms

none5siThis article aims at finding the most suitable waste heat recovery technology for existing and future offshore facilities. The technologies considered in this work are the steam Rankine cycle, the air bottoming cycle and the organic Rankine cycle. A multi-objective optimization approach is employed to attain optimal designs for each bottoming unit by selecting specific functions tailored to the oil and gas sector, i.e. yearly CO2 emissions, weight and economic revenue. The test case is the gas turbine-based power system serving an offshore platform in the North Sea. Results indicate that the organic Rankine cycle technology presents larger performances compared to steam Rankine cycle units, whereas the implementation of air bottoming cycle modules is not attractive from an economic and environmental perspective compared to the other two technologies. Despite the relatively high cost of the expander and of the primary heat exchanger, organic Rankine cycle turbogenerators appear thus to be the preferred solution to abate CO2 emissions and pollutants on oil and gas facilities. As a practical consequence, this paper provides guidelines for the design of high-efficiency, cost-competitive and low-weight power systems for offshore installationsrestrictedL. Pierobon;A. Benato;E. Scolari;F. Haglind;A. StoppatoL., Pierobon; Benato, Alberto; E., Scolari; F., Haglind; Stoppato, Ann