Historic rammed earth structures in Spain : construction techniques and a preliminary classification.

Conservation and repair of historic rammed earth sites should only be undertaken if there is a good understanding of the consequences of any intervention technique. Until recently there has been little interest in the characterisation of historic rammed earth construction, yet it is only with this understanding that successful conservation strategies can be adopted. A survey of around 60 historic rammed earth sites in Spain constructed between 967AD and 1837AD has recently been undertaken. While all the sites are built primarily in rammed earth, the construction techniques and state of repair vary greatly. The high density of historic rammed earth structures in the Iberian peninsula is likely due to the Muslim presence there from the 8th century onwards. Initial expansion, a period of civil war and eventual defeat by Christians led to the construction of a large number of fortifications, many constructed in rammed earth. A famous example is the Alhambra at Granada, but there are hundreds of smaller sites throughout Spain. By the end of the 15th century Christians had replaced Muslims through most of Spain, but rammed earth continued to be used in both vernacular and monumental architecture. Examples of historic construction techniques are presented and common features of historic rammed earth construction are identified. A classification is outlined and a clear development of the rammed earth technique is observed

Physical, mechanical and hygrothermal properties of lateritic building stones (LBS) from Burkina Faso

International audienc

Design and Analysis of High-pressure Casing of a Steam Turbine

AbstractContact pressure and pretension in bolts-analysis has been made easier in recent years due to the availability of high computational capabilities and flexibility in the computational methods using finite element analysis. In the present work, one such analysis is carried out blending the hand calculations and steady-state finite element analysis to evaluate the contact pressure in a high pressure steam turbine casing. The work involves design considerations, design checks, validation and sensitivity analysis to achieve the design criteria to fulfill the structural requirements for mechanical integrity. During the last several years the primary changes to the design of steam turbines have focused on improving their efficiency, reliability and reducing operating costs. Siemens Power Generation, for example, has improved the overall efficiency and availability of its steam turbines by decreasing the steam flow energy losses in each of the steam turbines components. The steam turbine unit largely influences the efficiency and reliability of power stations. Any improvement in the design of steam turbine enables more efficient use of fuel and results in reduced cost. The high pressure steam at 565°C and 156bar pressure passes through the high pressure turbine. The exhaust steam from this section is returned to the boiler for reheating before being used. On leaving the boiler reheater, steam enters the intermediate pressure turbine at 565°C and 40.2bar pressure. From the intermediate pressure turbine, the steam continues its expansion in the three Low pressure turbines. The steam entering the turbine is at 306°C and 6.32bar. To get the most work out of the steam, the exhaust pressure is kept very low. The casing thus witnesses, energy of the steam turned into work in HP and IP stages. So, the design of the casing is a very important aspect

Modeling the effect of bioreactor pH on Chinese Hamster Ovary (CHO) cell metabolism and site-specific N-linked glycosylation of VRC01

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Life cycle analysis of environmental impacts of earthen materials in the Portuguese context: Rammed earth and compressed earth blocks

In the Portuguese context, the life cycle assessment of building materials is still in its infancy. So far, there is only a small number of Environmental Product Declarations (EPDs) available, all target for industrially based materials. Although vernacular earthen materials are seen as ecological materials, with low potential environmental impacts, there are no studies that allow to quantitatively compare these materials with conventional ones, according to the applicable standards. In the case of Portugal, there are no EPDs or studies for these materials and the studies available worldwide are hard to compare, since they not follow the same life-cycle assessment methodology. This paper aims at contributing to a better understanding about the environmental performance of earthen materials by presenting results from the life cycle assessment of Compressed Earth Blocks (CEBs) and Rammed earth, based on specific life cycle inventory values obtained from a producer company, following the guidance provided by the standard EN15804. Among other conclusions, results show that CEB and Rammed earth have a total Embodied Energy of 3.94 MJ/block and 596 MJ/1m3 and a Global Warming Potential of 0.39 kg CO2 eq/block and 47.5 kg CO2 eq./1m3, respectively. In a cradle-to-gate analysis of different walls, the use of earthen building elements can result in reducing the potential environmental impacts in about 50%, when compared to the use of conventional ones. Additionally, the advantages of using earthen materials are also discussed for the different building life-cycle stages, focusing on the possibility to recycle these materials in a closed-loop approach.FEDER funds through the Competitivity and Internationalization Operational Programme (POCI) and by national funds through FCT—Foundation for Science and Technology within the scope of the project with the reference POCI-01-0145-FEDER-029328, and of the Ph.D. grant with the reference PD/BD/113641/2015, that were fundamental for the development of this study. The authors also wish to thank the construction company for providing the life cycle inventory data and helping this research wor

Trajectories of tuberculosis-specific interferon-gamma release assay responses among medical and nursing students in rural India

AbstractBackgroundInterferon gamma release assays (IGRAs) have been shown to be highly dynamic tests when used in serial testing for TB infection. However, there is little information demonstrating a clear association between TB exposure and IGRA responses over time, particularly in high TB incidence settings.ObjectivesTo assess whether QuantiFERON-TB Gold In-Tube (QFT) responses are associated with occupational TB exposures in a cohort of young health care trainees in India.MethodsAll medical and nursing students at Mahatma Gandhi Institute of Medical Sciences were approached. Participants were followed up for 18months; QFT was performed 4 times, once every 6months. Various modeling approaches were used to define IFN-gamma trajectories and correlations with TB exposure.ResultsAmong 270 medical and nursing trainees, high rates of conversions (6.3–20.9%) and reversions (20.0–26.2%) were found depending on the definitions used. Stable converters were more likely to have had TB exposure in hospital pre-study. Recent occupational exposures were not consistently associated with QFT responses over time.ConclusionIFN-gamma responses and rates of change could not be explained by occupational exposure investigated. High conversion and subsequent reversion rates suggest many health care workers (HCWs) would revert in the absence of treatment, either by clearing the infection naturally or due to fluctuations in the underlying immunological response and/or poor assay reproducibility. QFT may not be an ideal diagnostic test for repeated screening of HCWs in a high TB incidence setting