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Gaitani N.,National and Kapodistrian University of Athens | Santamouris M.,National and Kapodistrian University of Athens | Cartalis C.,National and Kapodistrian University of Athens | Pappas I.,Green Evolution | And 4 more authors.
Sustainable Cities and Society | Year: 2014

Integrating sustainability in urban design is a prerequisite for adequately addressing the urban challenges related to climate change, resource availability, environmental degradation and energy consumption. For the integration to be well formulated, urban planners need comprehensive microclimatic information at adequate spatial and temporal scales so as to define the bioclimatic design targets of the urban area concerned. In this study a medium size city (Acharnes, built at the southern foothills of Mt Parnitha, at a distance of 10 km north of Athens) is examined in terms of its thermal characteristics and the resulting thermal comfort conditions in municipal open spaces. Results show significant thermal loads for specific city areas as well as use of materials which result in adverse thermal conditions and in poor thermal comfort. On the basis of the results, specific guidelines are defined for the sustainable urbanisation of the city of Acharnes, in particular for an urban regeneration project concentrated at the centre of the city. The approach reflects a pattern which may be well applied in cities of respective size and urban characteristics and in similar climatic zones. © 2014 Elsevier Ltd. All rights reserved. Source

Accelerated Reliability/Durability testing (ART/ADT) is an extremely important and quite complicated problem of reliability theory and practice. It is known to be today the most efficient reliability estimation of equipment and systems. The main problems reliability engineer withstands with in connection with the accelerated tests are twofold: 1How to be sure that we can successfully and appropriately apply the acceleration to the system under observation (SUO)2How to handle statistics obtained when the situation is not "clear-cut" This paper is dealing with each of the above questions trying to give a comprehensive organizational and statistical framework for an accelerated Reliability test planning, tracking and decision making. Accurate prediction and control of reliability and durability plays a very important role in the profitability of a product. Service costs for products within the warranty period or under a service contract are a major expense and a significant pricing factor. Proper spare part stocking and support personnel hiring and training also depend upon good reliability fallout predictions. On the other hand, missing essential reliability targets may raise contractual penalties, tangible and intangible costs in the future. The paper concludes the united accelerated reliability testing approach for collecting accelerated/field reliability data for a class of products without sequence effect, so called Products Invariant to Order of Load Condition (PIOLC). Then the paper suggests a universal numerical data analysis procedure for decision making about the distribution parameters predictable values, based on Maximum Likelihood Evaluation method and Cross-Entropy optimization approach. Copyright © 2012 SAE International. Source

Fachinger J.,Furnaces Nuclear Applications Grenoble | Grosse K.-H.,Furnaces Nuclear Applications Grenoble | Seemann R.,ALD
Proceedings of the International Conference on Radioactive Waste Management and Environmental Remediation, ICEM | Year: 2010

The natural occurrence of graphite proves its geological stability over long time periods and therefore it could be considered as a matrix for embedding radioactive waste. However its porous structure affects the possible use of graphite as long term stable waste matrix for final disposal. Aqueous phases can penetrate the pore system and radionuclides adsorbed on the surface can be leached. Furthermore slow corrosion in aquatic phases can be induced by high irradiation dose rates in the range of 10-5 to 10-7 gm-2d-1. Therefore radiation induced corrosion process cannot be neglected in geological time scales. These problems can be solved with a graphite material with a closed pore system. A graphite composite material with an inorganic binder has been developed with a density > 99.7 % of theoretical density and a negligible porosity. An initial calculation predicts that the life time of the graphite will be at least 2 orders of magnitude higher than porous graphite. This material represents a long term stable leaching resistant matrix applicable for the embedding of irradiated graphite (i-graphite). Natural graphite can be added to improve the compaction behavior and mechanical properties. Additional applications could be the embedding of other radioactive wastes in this matrix. © 2010 by ASME. Source

Heuer V.,ALD | Faron D.R.,General Motors | Bolton D.,ALD Thermal Treatment | Lifshits M.,ALD Thermal Treatment | Loeser K.,ALD
Journal of Materials Engineering and Performance | Year: 2013

The paper presents how the "Dynamic Quenching" and "Reversing gas flow" processes are successfully applied on internal ring gears and planetary gears for a 6-speed automatic transmission. The specific challenge was to reduce distortion in such a way that subsequent machining operations are entirely eliminated. As a result of extensive development in the quenching process, it was possible to meet the design metrological requirements. The internal ring gears have been in continuous production since 2006. By utilizing the special CFC fixtures and quench methodology of "Dynamic Quenching," the customer was able to achieve the design intent, while eliminating all machining operations of the ring gears following LPC/HPGQ. Subsequent testing and monitoring over a 2-year period progressively demonstrated that conformance. Therefore, quality inspection was reduced accordingly. © 2013 ASM International. Source

Fachinger J.,Furnaces Nuclear Applications Grenoble | Grosse K.H.,Furnaces Nuclear Applications Grenoble | Hrovat M.,ALD | Seemann R.,ALD
Nuclear Engineering and Design | Year: 2012

The reflector graphite of an HTR reactor has to be handled as radioactive waste after the operational period of the reactor. However the waste management of irradiated graphite from Magnox reactors shows, that waste management of even low contaminated graphite could be expensive and requires special retrieval, treatment and disposal technologies for safe long term storage as low or medium radioactive waste. However the reflector graphite could be transferred into long term stable embedding matrix for high level radioactive waste especially for HTR fuel elements. This can be achieved by closing the pore system of the graphite with a stable inorganic binder, e.g. glass. First investigations proved the sealing of the pore system and the potential for embedding HTR fuel pebbles. © 2011 Elsevier B.V. Source

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