2,360 research outputs found
The Recognition of Fires Originating from Photovoltaic (PV) Solar Systems
No full textThere has been an observable increase in the fitting of photovoltaic (PV) solar panels on the roofs
of buildings in the UK over the last decade. The origin of some fires in domestic and commercial
properties has been attributed to PV systems. This thesis examines the ability of fire examiners to
recognise and record details of fires believed to have originated from PV systems, as well as
investigating the effect of internal heating in direct current (DC) isolators to the point at which they
fail.
National fire data was examined along with the methods for collecting and collating these data.
This clarified that national fire data cannot identify the specifics of electrical fires. Validity of these
data was then tested by identifying the confidence and competence in the recognition of the origin
of fire, (especially when associated with PV systems), of some fire staff responsible for collecting
fire data. This suggests that some fire scenes examiners are not confident in their own ability to
recognise fires originating from PV systems. Evidence for fires occurring in PV systems in Kent
between 2009 and 2014 was then examined, including a cold case forensic review of the
evidence. This provided an indication that a potential common point of failure, which may lead to
fire originating from a PV system, was to be found within the DC section of the PV circuits and
probably within the DC isolator switch itself. Experimentation revealed that internal heating of a
terminal connection can lead to changes of the phase of the insulating material, causing failure of
structural integrity and therefore allowing an arc to be established. Observable post fire indicators
associated with this mechanism of failure have been identified as well as hydrocarbons evolved
from pyrolysis of isolator insulating material.
Finally, areas for further experimental research and training of fire staff are suggested as well as
the modification of recording mechanisms and building regulations
Modificazioni morfo-strutturali placentari nel ritardo di crescita asimmetrico idiopatico [Morphological and structural placental changes in intrauterine growth-restricted fetuses]
No full textObiettivo: valutare le alterazioni dello sviluppo e della struttura dei villi conati di placente di gravidanze con ritardo di crescita fetale asimmetrico idiopatico (IUGR) tardivo.
Pazienti e metodi: sono state esaminate 45 placente di pazienti con IUGR idiopatico con parto, per via vaginale o addominale, espletato dal gennaio 2001 al dicembre 2007. L’esame istologico è stato condotto secondo le linee guida del Gruppo Italiano di Anatomia Patologica. La diagnosi di IUGR è stata posta sulla base dell’evidenza clinica ed ultrasonica di ridotta crescita fetale e basso peso neonatale in associazione a riduzione del liquido amniotico e a placenta “matura” all’esame USG.
Risultati: l’esame istologico ha evidenziato lesioni dello sviluppo e della struttura dei villi tipici della ipoperfusione cronica placentare così definite: maturazione accelerata dei villi (ipermaturità villare), villite ischemica (equivalente a microinfarti) ed infarti. In 10 casi, insieme a tali lesioni, ne e stata identificata un ‘altra, definita “ipercapilla-rizzazione dei villi”, che si associa ad una condizione dÏ ipossia relativa del sangue materno che circola tra i villi.
Conclusioni: il ritardo di crescita intrauterino asimmetrico idiopatico può essere ricondotto ad alterazioni dell’angiogenesi e vasculogenesi che avvengono nelle fasi iniziali della gravidanza. Ciò determina una condizione di ipossia placentare con alterazioni dello sviluppo dei villi tipici della ipoperfusione cronica placentare.Objective: to evaluate the structural and developmental abnormalities of villous tissue coming from placentas of fetuses with IUGR. Patients and methods: placental examination of 45 patients with idiopathic IUGR was carried out in accordance with the guidelines of the "Gruppo Italiano di Anatomia Patologica". The diagnosis of IUGR was made on the basis of fetal growth restriction, amniotic fluid reduction and placental US imaging. Results: the placental microscopic examination showed villous alterations tipical of chronic placental ipoperfusion: ischemic villitis, accelerated villous maturity and placental infarctions. There was evidence of enhanced villous capillarization maybe due to a relative hypoxia of maternal intervillous circulating blood in ten placentas. Conclusion: asymmetric idiopathic IUGR seems to be correlated with alterations of angiogenesis in the initial pregnancy steps with resulting chronic placental ipoperfusion in late pregnancy
Su un caso di mola vescicolare ricorrente con malattia trofoblastica persistente
No full textViene riportato il caso di una paziente di 30 anni, nullipara, con terza mola vescicolare consecutiva, trattata con tre revisioni di cavità e tre cicli di chemioterapia con methotrexate per malattia trofoblastica persistente. Sono discussi gli attuali orientamenti sulla patogenesi delle forme familiari ricorrenti e la possibile terapia per quelle pazienti con mola ricorrente che non siano portatrici di anomalie genetiche specifiche
L’isterectomia peripartum: la nostra esperienza
No full textObiettivo: determinare l'incidenza, l'indicazione e l'associazione con il parto cesareo dell'isterectomia peripartum (I.P.), la morbilità e la mortalità materna e neonatale. Materiale e metodo: sono stati esaminati tutti i casi di isterectomia peripartum osservati presso l’U.O. di Ostetricia e Ginecologia dell'A.O.S. S. Antonio Abate di Trapani dall’1/01/2001 al 31/05/2006. Risultati: sono stati eseguiti 13 interventi di I.P. pari al 2,26‰ parti di cui 46,1% come isterectomia totale, e 53,9% come isterectomia
subtotale. Il 69,2% degli interventi praticati è stato eseguito in condizioni d'emergenza mentre il 30,8% è stato programmato. Le indicazioni sono state: placenta previa accreta (38,4%), placenta accreta n.i. (7,6%), metrorragia da distacco intempestivo di placenta, Hellp sindrome e CID (38,3%), atonia uterina resistente a terapia medica
(15,5%) e rottura d'utero (7,6%). Otto pazienti (61,6%) erano precesarizzate. In 12 pazienti (92,4%) l'intervento è stato eseguito durante o subito dopo parto cesareo. È stata osservata una morte materna per embolia polmonare mentre, per quanto riguarda la morbilità, il 38,4 % delle pazienti è stato trasferito in terapia intensiva, una paziente è stata sottoposta a 4 laparotomie successive. Non si è avuto
alcun caso di mortalità neonatale. Conclusioni: la placenta previa accreta è la più comune indicazione all'intervento di isterectomia peripartum; essa è proporzionalmente
associata con il numero di pregressi parti cesarei che predispongono la cavità uterina ad inserzioni più basse e profonde
Solar PV hosting capacity: Grid-based vs. market-based scenarios
No full textAssessing the capability of a distribution grid to accommodate new solar PV installations, namely its hosting capacity (HC), has been a prevalent research topic. Although providing a technical limit to how much additional solar PV can be integrated into a distribution grid without trespassing operational limits, commonly used HC analysis (HCA) does not consider consumer preferences or the economic feasibility of installations. Using a market-based optimal power flow (MBOPF) and HCA, we compare the economic and technical limits of solar PV capacity integration in low voltage distribution systems (LVDS). Findings illustrate that (1) the PV HC computed using grid limits only does not give a complete picture of solar PV capacity integration potential, (2) linear, deterministic power flow is not a foolproof method for assessing the network-secure amount of PV, and (3) the number of technically feasible installation sites supersedes the economically feasible ones.Green 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.Energy and Industr
PV-boats: Design issues in the realization of PV powered boats
No full textPV integration in boats is rarely seen, but offers clean and silent transportation while on the water. In order to research the PV realization into boat design challenges, the University of Twente and the NHL hogeschool, both in the Netherlands, started a joined research into PV integration in boats. By studying 3 cases, PV boat specifications and the key design challenges are researched. The first case, the Frisian Solar Challenge 2010, offered the possibility to gather information about 44 innovative PV powered racing boats. The Frisian Solar Challenge is a 5 day 220km race for PV powered boats. Boats need to be fast, efficient and reliable to finish the race at high positions. The second case shows the NHL hogeschool\u92s PV powered racing boat design and building process which attended the Frisian Solar Challenge 2010. The third case is a study in PV powered boats found worldwide. From 105 boats, specifications are collected to learn recent developments in PV powered boats. From these 3 cases follows that light weight is one of the key parameters to build a successful PV powered boat. Especially PV modules with lower weight can bring successful PV powered boat designs. Furthermore, boats equipped with monohull designs offer high efficiency with low drag. However, catamaran designs prove to be successful as well, bringing higher stability in boat designs. Mature technology is needed to sail with reliable hardware
Comprehensive modelling and sizing of PV systems from location to load
No full textPhotovoltaic (PV) systems are progressively used for decentralized electricity generation. To obtain the maximum yield from such systems, optimisation of all components is essential. In this contribution, we provide a comprehensive modelling and sizing of PV systems for any location. Three applications are here presented providing real time monitoring of PV potential, accurate prediction of yield taking into account thermodynamic temperature effects, optimization of modules orientation addressing the effects of shading and efficient sizing of inverter for a higher yield output. When combined, these models can accurately predict the real time performance of any PV system.Accepted Author ManuscriptPhotovoltaic Materials and DevicesDC systems, Energy conversion & Storag
PV Module Integrated Converter for Distributed MPPT PV Systems
No full textDriven by constant advances and cost reductions in photovoltaic (PV) technology,together with incentive government policies toward cleaner environment, the PV energy became one of the fastest growing market in the world. In many countries the amount of installed PV power is increasing at an exponential rate, in all sectors from large utility scale power plants to small residential PV systems.DC systems, Energy conversion & Storag
Approaching nearly zero energy of PV direct air conditioners by integrating building design, load flexibility and PCM
No full textThe energy matching of PV driven air conditioners is influenced by building load demand and PV generation. Merely increasing energy performance of building or PV capacity separately may improve the energy balance on a large time resolution, the real-time energy mismatching problem is still serious. In this study, a coordinated optimization method of PV capacity, building design, and load flexibility is proposed for improving the real-time energy matching of PVAC system. Then, a methodology integrating data mining method (XG Boost) and parametric simulation was developed to identify the determinant parameters of PV system and building design, exploring feature importance and correlations. The results of XG Boost indicate that the PV capacity, shape factor, and SHGC are the most critical factors. Finally, based on the optimized building design, the PCM layer was applied to improve the real time energy matching. To achieve a goal of 90 % ZEP, the PCM capacity can be decreased by 50.4 % and 62.8 % in Guangzhou and Shanghai in the optimized building. Moreover, the PV capacity can be reduced by 23 % in Guangzhou. The findings of this study provide practical guidance for designing PVAC system coupling with building design and energy storage devices.Green 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.Environmental & Climate Desig
Highly Compact Partial Power Converter for a Highly Efficient PV-BESS Stacked Generation System
No full textThe inherently intermittent nature of photovoltaic (PV) energy has brought increasing interest towards the integration between PV sources and Battery Energy Storage Systems (BESS). In this paper, a Series Partial Power Processing (PPP) converter based on Capacitive Power Transfer (CPT) is proposed to integrate PV and BESS in a grid-connected inverter system. The proposed converter has been simulated according to a PV string capable to provide 1430 W under full irradiance conditions, a BESS nominal voltage equal to 215 V and a solar inverter assumed to operate with a minimum voltage of 150 V and a maximum current of 10 A. Simulation tests carried out at different conditions of solar radiation and required load power aim at demonstrating the correct operation of the proposed system.Green 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.DC systems, Energy conversion & Storag
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