174 research outputs found

    The illusion of comparable European IFRS financial statements. Beliefs of auditors, analysts and other users

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    Reaching higher comparability was one of the main goals of the implementation of the International Financial Reporting Standards (IFRS) in the European Union in 2005. However, national accounting traditions and cultural differences continue to cause differences in the application of IFRS (KPMG & von Keitz, 2006). European IFRS financial statements might therefore be less comparable than users of these statements possibly assume. This study contributes by determining to what extent auditors, analysts and other users of European IFRS financial statements believe that these statements are comparable and what they perceive to be the most important problem areas when it comes to comparability. Our survey of 426 individuals reveals that only 41% of the respondents believe that European IFRS financial statements are comparable. The more experienced respondents are, the less they believe in the comparability of these statements. Overall, 13 areas are perceived as problematic for the comparability of IFRS financial statements by at least half of the respondents. The three main issues that appear in most of these problem areas are interpretation differences, subjectivity and disclosure differences.Comparability, European IFRS financial statements, survey

    Natural Night Ventilation in Office Buildings: Performance Evaluation Based on Simulation, Uncertainty and Sensitivity Analysis

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    Sinds 1 januari 2006 is in de Europese Unie de richtlijn betreffende de energieprestatie van gebouwen van kracht. Hiermee beoogt de EU het energieverbruik terug te dringen en aan de Kyotonormen te voldoen. De gebouwsector is immers verantwoordelijk voor 40% van het totale energieverbruik. De energieprestatie van een kantoorgebouw kan o.a. verbeterd worden door energie-intensieve koeling of ‘air conditioning’ te vervangen door nachtelijke natuurlijke ventilatie. Hierbij zorgen wind en het schouweffect ervoor dat koele buitenlucht ‘s nachts doorheen het gebouw stroomt en daarbij de wanden afkoelt waarin de warmte van de vorige dag is opgeslagen. De prestaties van deze koeltechniek kunnen met gebouwsimulatie voorspeld worden. Niettemin bestaat er nog onduidelijkheid over de betrouwbaarheid van deze simulatieresultaten t.g.v. de aannames van de gebruiker in de invoer. Aangezien dit belangrijke gevolgen kan hebben voor het ontwerp- en beslissingproces, wordt in dit doctoraatsonderzoek een methodologie ontwikkeld die de prestaties van nachtelijke natuurlijke ventilatie met gebouwsimulatie evalueert, rekening houdend met de onzekerheden in de invoer. Hierbij worden de prestaties gekenmerkt door het bereikte thermisch comfort in het kantoorgebouw. Om dit comfort te evalueren, wordt een simulatiepakket gebruikt dat tegelijkertijd de temperaturen en de luchtdebieten in het gebouw berekent. Onzekerheids- en gevoeligheidsanalyse bepalen de invloed van de onzekerheden in de invoer. Ze berekenen zowel de variatie op het thermisch comfort als de parameters in de invoer die hiervoor verantwoordelijk zijn. Deze methodologie leidt tot praktische richtlijnen om nachtelijke natuurlijke ventilatie te ontwerpen en dit ontwerp vervolgens te evalueren. Deze richtlijnen worden toegepast op twee kantoorgebouwen in België

    Analysis of resilience of ventilative cooling technologies in a case study building

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    Buildings globally are subjected to climate change and heatwaves, causing a risk of overheating and increasing energy use for cooling. Low- energy cooling solutions such as night cooling are promising to realize energy reduction and climate goals. Apart from energy performances, resilience is gaining importance in assessing the performance of the building and its systems. Resilience is defined as “an ability to withstand disruptions caused by extreme weather events, man-made disasters, power failure, change in use and atypical conditions; and to maintain capacity to adapt, learn and transform.” However, there is a clear lack of Resilience indicators specific for low energy cooling technologies. In this paper, the resilience of the night cooling in a residential building in Belgium is assessed for two external events: heat wave and shading failure. This paper shows the first attempt of a resilience indicator for night cooling as the effect on the shock of solar shading failure, heat wave or combination of both. It take 3.4 days to bring down the temperature below 25?, in case of shading failure and heatwaves compared to 9 hours in the reference case. Further research is needed to determine resilience indicators as a performance criteria of low-energy cooling systems

    Paleo-fluids characterization and fluid flow modelling along a regional transect in Northern United Arab Emirates

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    In the Northern Emirates, Jurassic and Lower Cretaceous platform carbonates of the Musandam parautochthonous units are tectonically overlain by siliciclastic units of the Hawasina-Sumeini allochthon, which derive from the former paleo-slope domain and a more distal basinal portion of the Arabian margin of the Tethys, respectively. All these tectonic units display numerous evidences of paleo-fluid circulations, accounting for dolomitisation and recrystallisation of the rock matrix (Musandam Platform units), as well as cementation of fractures. Polymict breccias of Upper Cretaceous Ausaq Formation which underlay the sole thrust of the Hawasina-Sumeini allochthon also record episodes of hydraulic fracturing, whereas fluid inclusion data indicate precipitation at high temperature in relation to paleo-fluid flow. Petrography of thin-sections (conventional and cathodoluminescence microscopic techniques) as well as fluid inclusion and stable isotopes analyses, were combined with micro-tectonic studies. These analytical data document (1) the paragenetic sequence of diagenetic products for the Musandam Platform (which constitutes a carbonate reservoir analogue) and Sumeini units of the Dibba Zone, as well as (2) the nature of the paleo-fluids circulating along fractures and the sole thrust of the Hawasina-Sumeini allochthon. The main results of this petrographic approach are qualitative, evidencing (1) the rapid and vertical transfer of hot fluids in the vicinity of the former slope to platform transition, accounting for episodes of hydrothermal dolomitisation, as well as (2) early (i. e. pre-orogenic) and late (i. e. post-orogenic) episodes of emersion of the carbonate units, accounting for additional interactions with meteoric fluids and karstification. In order to better link these diagenetic events with the overall burial, thermal and kinematic evolution of the Arabian margin, basin modelling with Ceres2D, including fluid flow and pore-fluid pressure modelling, was subsequently performed along a regional transect (D4) located in the vicinity of the samples localities and cross-cutting the Northern Oman Mountains from Dibba in the east up to the Arabian Gulf in the west. New subsurface constraints provided by deep seismic profiles were used to constrain the architecture of the cross-section, and to test various hypotheses on the lateral and vertical connection, timing and hydrodynamic behaviour of the faults. This Ceres basin modelling also provides new quantitative estimates of the paleo-fluid pathways, of the timing and velocities of the fluid transfers and of the evolution of pore-fluid pressures. Ultimately, this integration of petrographic studies on surface samples and coupled kinematic and fluid flow basin modelling provides an updated scenario for the succession of tectonically controlled episodes of fluid rock interactions, namely dolomitisation and karstification recorded in the Mesozoic platform carbonates of the Northern Emirates. © 2010 Saudi Society for Geosciences

    Dynamic interactions between the ground heat exchanger and environments in earth–air tunnel ventilation of buildings

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    Earth–air tunnel ventilation is an energy efficient method of preheating or cooling of supply air to abuilding. The purposes of this study are to investigate the performance of earth–air heat exchangersunder varying soil and atmosphere conditions and the interactions between the heat exchanger andenvironments. A computer program has been developed for simulation of the thermal performance of anearth–air heat exchanger for preheating and cooling of supply air, taking account of dynamic variationsof climatic, load and soil conditions. The program solves equations for coupled heat and moisture transferin soil with boundary conditions for convection, radiation and evaporation/condensation that vary withthe climate both at the soil top surface and inside the heat exchanger. The importance of dynamic inter-actions between the heat exchanger, soil and atmosphere is illustrated from the comparison of the heattransfer rates through the heat exchanger. The predicted heat transfer rate varies with operating time anddecreases along the passage of air in the heat exchanger. Neglecting the interactions would significantlyover-predict the heat transfer rate and the amount of over-prediction increases with operating time

    Análise de incertezas físicas em simulação computacional de edificações residenciais

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    Resumo O objetivo deste trabalho é analisar incertezas físicas em simulação computacional de uma edificação residencial e sua implicação no desempenho térmico. O experimento foi elaborado com o método de Monte Carlo, que envolve as propriedades térmicas e físicas dos materiais da edificação. Foi analisada a sensibilidade das variáveis com coeficientes de regressão e correlação. Considerou-se o critério de graus-hora de desconforto por calor e por frio para o clima de Florianópolis, SC, conforme limites de conforto térmico adaptativo. Os resultados mostraram que as incertezas obtidas nos graus-hora são relativamente grandes, sendo de 32% no desconforto por frio e de 53% no desconforto por calor. Grande parte da incerteza é decorrente da temperatura média mensal do solo. Outras variáveis, como a absortância solar da cobertura e o calor específico da argamassa das paredes, resultam em impacto relevante no desconforto por calor, bem como a massa específica da argamassa e o calor específico da cerâmica das paredes no desconforto por frio. Essas variáveis precisam de maior precisão, seja por meio de bases de dados mais confiáveis, ou mesmo por medições em campo e/ou em laboratório

    Relationship between karstification and burial dolomitization in Permian platform carbonates (Lower Khuff - Oman)

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    Large breccia fabrics associated with karst constitute an important structure in massive limestone successions. The dimensions and shapes of breccia structures are controlled by the initial fracture pattern of the limestone and preferential pathways of the karstifying fluids, but subsequently breccia fabrics can also govern the migration of later fluids. Therefore, breccias are highly relevant features to capture for reservoir characterisation. Outcrop analogues for Lower Khuff units in the Middle East present in the Central Oman Mountains reveal brecciated fabrics up to 10’s of meters in diameter. These brecciated units are closely associated with dolomite bodies of late diagenetic origin. Based on an integrated set of data, the breccias are interpreted as collapsed karst cavities either formed by meteoric or hypogenic fluids. The exact origin of the fluids could not be constrained due to an overprint by later dolomitizing fluids. Based on the composition of the clasts and matrix in the breccias, two dolomitization events are interpreted to have affected the succession, one prior to (early diagenetic [ED] dolomite) and one after brecciation (late diagenetic [DT2] dolomite). Dolomite of shallow burial origin (ED dolomite) was only observed as clasts within breccia and is much more frequent than late diagenetic (medium to deep burial) dolomite clasts. Thus, the timing of the brecciation and collapse is assumed to postdate shallow burial early diagenetic dolomitization. Late diagenetic replacive dolomite (DT2 dolomite) forms 90% of the matrix in the breccia fabrics with the exception of a small area that was not affected by dolomitization, but is rarely present as clasts. Stable isotope measurements [δ18O: − 2.5‰ to − 6‰ VPDB and δ13C: 2.9‰ to 4.8‰ VPDB] suggest a burial origin for the late diagenetic dolomite potentially with the participation of hydrothermal fluids. The dolomitized matrix indicates a migration of late dolomitizing fluids subsequent to or postdating the collapse of the karstic cavities. Thus, early karstification processes seem to have played a big role in controlling subsequent loci of late dolomitization in the Oman Mountains, and potentially in other similar settings elsewhere

    Resilient cooling strategies – A critical review and qualitative assessment

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    The global effects of climate change will increase the frequency and intensity of extreme events such as heatwaves and power outages, which have consequences for buildings and their cooling systems. Buildings and their cooling systems should be designed and operated to be resilient under such events to protect occupants from potentially dangerous indoor thermal conditions. This study performed a critical review on the state-of-the-art of cooling strategies, with special attention to their performance under heatwaves and power outages. We proposed a definition of resilient cooling and described four criteria for resilience—absorptive capacity, adaptive capacity, restorative capacity, and recovery speed —and used them to qualitatively evaluate the resilience of each strategy. The literature review and qualitative analyses show that to attain resilient cooling, the four resilience criteria should be considered in the design phase of a building or during the planning of retrofits. The building and relevant cooling system characteristics should be considered simultaneously to withstand extreme events. A combination of strategies with different resilience capacities, such as a passive envelope strategy coupled with a low-energy space-cooling solution, may be needed to obtain resilient cooling. Finally, a further direction for a quantitative assessment approach has been pointed out
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