1,676 research outputs found

    Bruce Bennett

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    A different kind of archival security: Three cases

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    Archival security is not just about guarding against theft and vandalism; it is about accountability and ethics and the potential challenges to archives and archivists. This essay considers three cases -the ownership and control of the records of indigenous peoples, the use of records of the U.S. Supreme Court, and the misadminstration of electronic mail messages to the White House. © Taylor & Francis Group, LLC

    Development of a calibration phantom for the optical imaging of the rat hat

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    In dieser Arbeit wird die Entwicklung eines Kalibrierphantoms beschrieben, das die optischen Eigenschaften des Rattenhirns widerspiegelt und die Kalibration einer hochempfindlichen CCD-Kamera ermöglicht. Als Lichtquelle diente eine LED, deren IntensitĂ€t mit Hilfe einer Referenzspannungsquelle und eines Temperatur-Kontrollsystems mit einer Genauigkeit von 2 ‰ eingestellt werden konnte.This thesis describes the development of a calibration phantom that simulates the optical properties of the rat brain and gives the occasion to calibrate a highly sensitive CCD-camera. For the light source an LED was used. With a temperature control system and a precision voltage reference the intensity of the LED could be adjusted with the accuracy of 2 ‰

    Dynamic thermal simulations for developing early-stage assessments for office buildings

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    Office buildings account for a large portion of the total energy consumption in Europe because due to increased comfort requirements almost all recent buildings are air-conditioned. This project is focused on the influence of thermal storage capacity of commonly used structure types of office buildings and different technical strategies on energy efficiency and thermal comfort. The technical parameter ventilation strategy is essential compared to the parameters structure type or window-to-wall ratio. Additionally a lighting control system based on solar radiation shows a high influence on the internal gains and in consequence on the overheating hours. The slab type respectively the accessibiltiy of the thermal mass has a significantly higher influence than the differences of “massivity” between solid and light weight structures

    Wie bilanzieren die europĂ€ischen Staaten in Luxemburg, Deutschland, Belgien, der Schweiz und in Frankreich? Ein Vergleich verschiedener nationaler Berechnungsvorschriften der Gesamtenergieeffizienz anhand von 9 klimatisierten BĂŒrogebĂ€uden und deren Realverbrauch

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    Die EU-Mitgliedsstaaten sind gemĂ€ĂŸ den Richtlinien 2002/91/EG und 2010/31/EU verpflichtet, die Gesamtenergieeffizienz von GebĂ€uden abhĂ€ngig von ihrer Art der Nutzung zu ermitteln und in einem Energiepass zu belegen. Die Ausgestaltung der Details des Berechnungsverfahrens und der Grenzwerte obliegt den Mitgliedsstaaten im Rahmen ihres nationalen Entscheidungsspielraums. FĂŒr 9 bestehende mittlere bis große BĂŒrogebĂ€ude mit Teil- und Vollklimatisierung wurden die Berechnungen der Gesamtenergieeffizienz nach den jeweiligen Berechnungsmethoden durchgefĂŒhrt und mit dem gemessenen realen Verbrauch verglichen. Die Abweichungen zwischen der berechneten Endenergie und dem tatsĂ€chlichen Verbrauch betragen zwar etliche 100% beim einzelnen Objekt, aber ca. 20 % im Mittel bei der Heizenergie. Bei der berechneten Endenergie des Stroms bestehen auch riesige Differenzen beim Einzelobjekt, aber im nationalen Vergleich im Mittel nur geringe Abweichungen zum Verbrauch, wobei der Stromverbrauch fĂŒr die BĂŒroausstattung geschĂ€tzt wurde. Die Abweichungen bei der Heizenergie und beim Strom im Mittel können als gut bezeichnet werden, wobei vor allem Belgien durch Über- und UnterschĂ€tzen beim Strom auffĂ€llt. Rund Ÿ der verbrauchten PrimĂ€renergie ist auf den elektrische Energie zurĂŒck zu fĂŒhren, wobei der Mittelwert von rund 400 kWh/m2 darauf hindeutet, dass die realen GebĂ€ude noch weit vom europĂ€ischen Ziel der „Nearly Zero Energy Buildings (NZEB)“ entfernt sind

    Modellierung und Bemessung von dĂŒnnwandigen Platten- und Schalentragwerken aus textilbewehrtem Beton

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    Als Großdemonstrator des Sonderforschungsbereichs 532 soll auf dem GelĂ€nde der FakultĂ€t fĂŒr Bauingenieurwesen der RWTH Aachen ein Ausstellungspavillon mit einer Dachkonstruktion aus Textilbeton errichtet werden. Der Beitrag zeigt die automatisierte Bemessung dieser komplexen Tragstruktur mit Hilfe eines hierfĂŒr entwickelten numerischen Bemessungsstools. Die Auswertung erfolgt fĂŒr alle Lastfallkombinationen nach DIN 1055-100 und unter BerĂŒcksichtigung der Reduktion der TragfĂ€higkeit der textilen Bewehrung infolge einer Umlenkung im Riss sowie einer Erhöhung der aufnehmbaren Textilspannungen infolge Biegebeanspruchung. Zur Ermittlung der TragfĂ€higkeit der Textilbetonschale wurden am Institut fĂŒr Massivbau Dehnkörper- und Biegeversuche durchgefĂŒhrt, die in Bewehrungsgrad und Dicke dem realen Bauwerk am Schalenrand entsprachen.Within the collaborate research center 532 at RWTH Aachen University the construction of an exposition hall with a double-curved roof structure consisting of textile reinforced concrete is currently planned. A numerical tool has been developed to calculate the necessary number of reinforcement layers. Further, the tool evaluates the characteristic stresses of the load case combinations in the ultimate limit state taking into account a reduction of the load-bearing capacity of the textile reinforcement due to alignment of the rovings in the crack bridge and a better activation of the inner filaments for bending induced tension. The resistance of the material has been determined in experimental investigations of tensile and bending specimens of the same thickness and reinforcement ratio as the planned shell structure

    How reliable are the models to study recent climate change ? A study of heat/cold waves and radiative fluxes trends over 1900-2010 using the model MAR in Belgium

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    This research aims to assess the ability of the regional climate model MAR ("ModÚle Atmosphérique Régional") to reconstruct the observed twentieth century climatology of extreme events and solar radiation in Belgium, as a necessary condition for reliable future projections. Simulations were performed by forcing MAR with several reanalyses: the ERA40/ERA-Interim, the ERA-20C and the NCEP/NCAR-v1. The results suggests that increasing air temperature would have generated decreasing relative humidity which would have lead to a decrease in cloudiness and an increase in solar downward radiation. This research illustrates the dependency between RCMs and their forcings. The forcing reanalyses can generate divergent trends while contrary to Global Climate Models (GCM), the reanalyses assimilate observations and are supposed to represent the same climate

    The impact of HIV exposure and maternal Mycobacterium tuberculosis infection on infant immune responses to bacille Calmette-Guérin vaccination.

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    OBJECTIVE: The objective of this study is to assess the effect of maternal HIV and Mycobacterium tuberculosis (Mtb) infection on cellular responses to bacille Calmette-GuĂ©rin (BCG) immunization. DESIGN: A mother-infant cohort study. METHODS: Samples were collected from mother-infant pairs at delivery. Infants were BCG-vaccinated at 6 weeks of age and a repeat blood sample was collected from infants at 16 weeks of age. BCG-specific T-cell proliferation and intracellular cytokine expression were measured by flow cytometry. Secreted cytokines and chemokines in cell culture supernatants were analysed using a Multiplex assay. RESULTS: One hundred and nine (47 HIV-exposed and 62 HIV-unexposed) mother-infants pairs were recruited after delivery and followed longitudinally. At birth, proportions of mycobacteria-specific proliferating T cells were not associated with either in-utero HIV exposure or maternal Mtb sensitization. However, in-utero HIV exposure affected infant-specific T-cell subsets [tumour necrosis factor-alpha (TNF-α) single positive proliferating CD4âș T cells and interferon-gamma (IFN-Îł), TNF-α dual-positive CD4âș T cells]. Levels of TNF-α protein in cell culture supernatants were also significantly higher in HIV-exposed infants born to Mtb-sensitized mothers. In the presence of maternal Mtb sensitization, frequencies of maternal and newborn BCG-specific proliferating CD4âș T cells were positively correlated. Following BCG vaccination, there was no demonstrable effect of HIV exposure or maternal Mtb infection on infant BCG-specific T-cell proliferative responses or concentrations of secreted cytokines and chemokines. CONCLUSION: Effects of maternal HIV and Mtb infection on infant immune profiles at birth are transient only, and HIV-exposed, noninfected infants have the same potential to respond to and be protected by BCG vaccination as HIV-unexposed infants

    Impact of the height imperfections of masonry blocks on the load bearing capacity of dry-stack masonry walls

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    Dry-stacked masonry walls gives rise to geometric imperfections: the height variation of different masonry blocks ΔH and the roughness of the support area Δh. This paper studies the effect of ΔH on the structural response and the load bearing capacity of masonry walls by highlighting the load percolation. Furthermore, an algorithm was developed to define a stress multiplier coefficient respecting the imperfections ΔH. The algorithm allowed predicting 77% of the amplified stress compared to the FE analysis and showed that the geometric imperfections govern the load percolation in a wall as well as the cracking mode and the bearing capacity
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