Vacuum mixing technology to improve the mechanical properties of ultra-high performance concrete

Ultra-high performance concrete is an important evolution in concrete technology, enabled by the combination of a good particle packing density, a suitable mixing procedure and compatible binders and admixtures. In the last decades a lot of research has been performed to explore the boundaries of this new type of concrete. Mixers equipped with a vacuum pump able to lower the mixing pressure from 1,013 to 50 mbar are an interesting way to improve the performance by lowering the air content. Profound research is necessary, because little is known about this technique of air content reduction. The influence of a reduced air content on the mechanical properties of ultra-high performance concrete is tested at The Magnel Laboratory for Concrete Research. This paper reports the results of the compressive strength, the splitting and bending tensile strength and the modulus of elasticity. All the mechanical properties after 28 days curing are improved by reducing the air content in the ultra-high performance concrete. An increase in compressive strength between 7 and 22 % is measured. The bending tensile strength increases maximum with 17 % and the splitting tensile strength gains 3-22 % in performance. Furthermore, the modulus of elasticity improves with 3-8 %. In conclusion, the air content can be controlled and a higher performance can be achieved by vacuum mixing technology. Finally, it is shown that the vacuum technology is not as effective in a 75 l capacity vacuum mixer as it is for a smaller vacuum mixer with a capacity of 5 l

Reserve Li/SOC12 Battery Safety Testing

A reserve Lithium/Thionyl Chloride Battery concept is developed and undergoing feasibility testing in terms of performance, safety and abusive conditions. The feasibility of employing a battery of this type to replace thermal batteries in certain applications is demonstrated. Excellent performance of a Li/SOCl2 reserve battery is obtained across the temperature range from 0 C to +44 C. Performance improvement over the thermal battery usage is greater by a factor of 3 when discharge time and energy density are compared. Performance over an expanded temperature range is also possible. Safety and abusive testing is accomplished successfully on a series of five units. Further performance improvements can be achieved with regard to battery weight and volume reductions

Watershed management in New Zealand : status and research needs

Nature has endowed New Zealand with unique geologic, climatic, and biotic conditions. Her volcanic cones and majestic Southern Alps and her verdant plains and rolling hills provide a landscape as rugged and beautiful as will be found anywhere. Her indigenous fauna and flora are often quite different from that of the rest of the world and consequently have been of widespread interest to biologists everywhere. Her geologic youth and structure and her island climate, in combination with the biological resources, have made a land which is ecologically on edge. These natural endowments along with the manner in which she has utilized her land, have given New Zealand some of the most spectacular and rapid erosion to be found. It is quite evident that geologic and climatic conditions combine to give unusually high rates of natural erosion. Present topographic features indicate the past occurrence of large-scale flooding as well. Prior to the arrival of the Maori, it is very likely that most of the land mass of New Zealand below present bush lines was covered with indigenous bush or forest. Forest fires of a catastrophic nature undoubtedly occurred as a result of lightning, and volcanic eruptions. The exposed soils left by these catastrophes contributed to natural deterioration. While vast areas of forest cover were destroyed, they probably were healed by nature with forest or with grass or herbaceous cover. Further, it is probable that large areas in the mountains were, as they are now, subject to landslides and slipping due to earthquakes and excessive local rainfall. Again, the healing process was probably rapid in most of such exposed areas

Experimental clean combustor program: Turbulence characteristics of compressor discharge flows

The results of turbulence measurements at the entrance to the diffuser duct of a large gas turbine are presented. Hot film and hot wire measurements were conducted over a compressor discharge temperature range of 450K to 608K. It was found that the turbulent intensity at the I.D. and midspan locations increases gradually from 6 + or - 1 percent at idle to 7 + or - 1 percent at approach; the turbulent intensity at the O.D. location increases from 7.5 + or - 0.5 percent at idle to 15 + or - 0.5 percent at approach. The energy in the velocity waves is uniformly distributed over a 0.1 to 5 kHz bandwidth, and the cut-off frequency is not a strong function of the engine operation. The axial length of the Fourier components within this bandwidth varies from 0.021 to 1.05m. The turbulence near the diffuser O.D. is of sufficient amplitude and scale to affect the flow to the front end sections of the burner

Impact of air entrainment on the microstructure and mechanical performance of high performance mortar

At the Magnel Laboratory for Concrete Research an intensive vacuum mixer which can regulate the air pressure is available. As such the amount of entrapped air in cementitious materials can be varied. The effect of the reduced air content due to vacuum mixing on the rheology and workability was already investigated in previous work. Furthermore, the previous work investigated the influence of entrained air on the rheological properties. The impact of vacuum mixing on the compressive strength and the microstructure of (ultra)high performance mortar is documented elsewhere. However, the impact of air entrainment on high performance mortar has not yet been published. Therefore, this paper will focus on the evolution of the pore structure of air-entrained high performance mortar by using mercury intrusion porosimetry, fluorescence microscopy and air void analysis. This data will enable to verify the pore diameters, often used to explain the evolution of the rheology by the ratio of shear stresses and the surface tension. Furthermore it explains the evolution of the density, the compressive strength and the bending tensile strength. The air entrainment was varied between 0 % abd 2.5 % wt.cement. As a consequence the air content was systematically increased. In case of the air void analyser, the amount of air cavities was increased from 1 % to 14 %. From the cumulative air void fraction it was noticed that pores with a diameter of 80 µm were dominant in the mortar. From data of the mercury intrusion porosimetry the amount of capillary pores was increased from 7.4 % and 22.2 %. The critical diameter at lower percentage of air entrainment was 40 nm, a more continuous curve was obtained for the highest percentages. Furthermore, the amount of pores situated between 10 µm and 100 µm were limited or not existing. In conclusion, this paper highlights the underestimation of the lareger air pores by mercury intrusion porosimetry. Besides this, the decrease in compressive strength and bending tensile strength can be explained by the changes in the pore structure. Finally, it was checked whether the increase in plastic viscosity due to air entrainment was caused by the air bubbles or by the polymer itself

Manumisiones Délficas

En el muro poligonal de] santuario de Delfos han podido regogerse una gran cantidad de inscripciones relativas a la liberación de esclavos por el procedimiento de su venta ficticia a la divinidad. La peculiaridad de las prácticas sociales ligadas a estas inscripciones impiden que los datos que éstas proporcionan puedan considerarse como significativos para la historia económica de Grecia Central. En particular, se señalan como peculiaridades el alto precio de los esclavos manumitidos, la importante presencia de manumisores vinculados muy estrechamente al santuario y la proporción desequilibrada de mujeres entre los esclavos liberados.______________________________Sur le mur polygonal du sanctuaire de Delphes on a pu recueillir une grande quantité d'inscriptions sur la libération desclaves par le procédé de leur vente fictive á la divinité. La particularité des practiques sociaux liées á ces inscriptions empéchent que les données qu'elles procurent puissent étre consídérées significatives you l'histoire économique de la Gréce Centrale. On signale comme particularités le prix élevé des esclaves affranchis, ¡'importante présence des affranchisseurs attachés trés étrotement au sanctuaire et la proportion déséquilibrée de femmes parmi les esclaves libérés.In the polygonal wall of Delphos sanctuary, a great number of inscriptions relative to the liberation of slaves by fictitiously sell them to a divinity have been gathered. The peculiarity from these social practices linked to these inscriptions prevent that the data they provide can be considered significant for the economic history of central Greece. Actually, they are indicated as peculiarities the high price of the slaves manumitted, the important presence of minimisers linked very closely to the sanctuary and the unbalanced proportion of women among the freed slaves

Comparisons between SCIAMACHY and ground-based FTIR data for total columns of CO, CH_4, CO_2 and N_2O

Total column amounts of CO, CH_4, CO_2 and N_2O retrieved from SCIAMACHY nadir observations in its near-infrared channels have been compared to data from a ground-based quasi-global network of Fourier-transform infrared (FTIR) spectrometers. The SCIAMACHY data considered here have been produced by three different retrieval algorithms, WFM-DOAS (version 0.5 for CO and CH_4 and version 0.4 for CO_2 and N_2O), IMAP-DOAS (version 1.1 and 0.9 (for CO)) and IMLM (version 6.3) and cover the January to December 2003 time period. Comparisons have been made for individual data, as well as for monthly averages. To maximize the number of reliable coincidences that satisfy the temporal and spatial collocation criteria, the SCIAMACHY data have been compared with a temporal 3rd order polynomial interpolation of the ground-based data. Particular attention has been given to the question whether SCIAMACHY observes correctly the seasonal and latitudinal variability of the target species. The present results indicate that the individual SCIAMACHY data obtained with the actual versions of the algorithms have been significantly improved, but that the quality requirements, for estimating emissions on regional scales, are not yet met. Nevertheless, possible directions for further algorithm upgrades have been identified which should result in more reliable data products in a near future

Investigation of the Mechanical and Electrical Properties of Elastic Textile/Polymer Composites for Stretchable Electronics at Quasi-Static or Cyclic Mechanical Loads

In the last decade, interest in stretchable electronic systems that can be bent or shaped three-dimensionally has increased. The application of these systems is that they differentiate between two states and derive there from the requirements for the materials used: once formed, but static or permanently flexible. For this purpose, new materials that exceed the limited mechanical properties of thin metal layers as the typical printed circuit board conductor materials have recently gained the interest of research. In this work, novel electrically conductive textiles were used as conductor materials for stretchable circuit boards. Three different fabrics (woven, knitted and nonwoven) made of silver-plated polyamide fibers were investigated for their mechanical and electrical behavior under quasi-static and cyclic mechanical loads with simultaneous monitoring of the electrical resistance. Thereto, the electrically conductive textiles were embedded into a thermoplastic polyurethane dielectric matrix and structured by laser cutting into stretchable conductors. Based on the characterization of the mechanical and electrical material behavior, a life expectancy was derived. The results are compared with previously investigated stretchable circuit boards based on thermoplastic elastomer and meander-shaped conductor tracks made of copper foils. The microstructural changes in the material caused by the applied mechanical loads were analyzed and are discussed in detail to provide a deep understanding of failure mechanisms.EC/H2020/825647/EU/Re-Thinking of Fashion in Research and Artist collaborating development for Urban Manufacturing/REFREA

Colonia Augusta Firma – Astigi (Écija, Seville): New Archaeological and Epigraphical Evidence

En este trabajo se ofrece una síntesis de las últimas novedades arqueológicas que están proporcionando las excavaciones en desarrollo en la plaza de Armas del antiguo alcázar de la ciudad. Se añaden a este panorama las aportaciones que brindan los recientes hallazgos epigráficos, incorporando algunas piezas inéditas.This paper offers a summary of the latest outcomes of archaeological excavations that are being carried out in the plaza de Armas of the old town’s alcázar. Contributions provided by epigraphic recent news are added to this panorama, incorporating some unpublished pieces.Unión Europea, Ministerio de Economía y Competitividad HAR2014-55857-PUnión Europea, Ministerio de Economía y Competitividad HAR2015-64392-C4-4-

Note about stamps on bricks, tegvlae and amphorae in "Colonia Avgvsta firma"

Se ofrece en este trabajo la edición de una serie de sellos sobre ladrillos, tegulae y ánforas documentados en diferentes excavaciones arqueológicas llevadas a cabo en Écija en los últimos años.In this paper is presented the edition of several stamps on bricks, tegulae and amphorae, found in archaeological excavations carried out in the last years in Écija.España. Ministerio de Ciencia e Innovación HAR2009-0882