Climate Control in Mediterranean Greenhouses

As climate control in greenhouses directly affects crop yields, there is an increasing trend for advancements in environmentally controlled agricultural-production techniques. In the Mediterranean region, the temperatures during the period from December to February are below 12°C when the daily total radiation 8.4 MJ/m2day. Based on the region?s climate data, greenhouses require heating during the period from November to March, ventilation and shading from February to May and cooling from June to September. In order to maintain day and night temperatures of 18/16°C, annual heat energy requirement of PE greenhouses is 95-256 kWh/m2. In view of environment and production costs, conservation of heating energy is as important as heating itself. Heat energy saving is about 37% when energy curtains are used. Greenhouse temperature can be increased by 8°C in palliative non-heated greenhouses where energy curtains and water mattresses are used in addition to passively used solar energy. Ventilation openings at the roofs of these greenhouses should adequately be 20-25%. When outside noon-time temperature is above 30°C in June, evaporative cooling of greenhouse is essential. Depending on outside humidity and volume of exchanged air for cooling, a temperature difference of 6°C can be achieved with evaporative cooling of greenhouses in August

Optimización de la resistencia a compresión de lechadas de cemento reforzadas con aditivos

The Taguchi method was used in this study to optimize the unconfined (7-, 14- and 28-day) compressive strength of cement-based grouts with bentonite, fly ash and silica fume admixtures. The experiments were designed using an L16 orthogonal array in which the three factors considered were bentonite (0%, 0.5%, 1.0% and 3%), fly ash (10%, 20%, 30% and 40%) and silica fume (0%, 5%, 10% and 20%) content. The experimental results, which were analyzed by ANOVA and the Taguchi method, showed that fly ash and silica fume content play a significant role in unconfined compressive strength. The optimum conditions were found to be: 0% bentonite, 10% fly ash, 20% silica fume and 28 days of curing time. The maximum unconfined compressive strength reached under the above optimum conditions was 17.1 MPa.En el presente trabajo se ha intentado optimizar, mediante el método de Taguchi, las resistencias a compresión (a las edades de 7, 14 y 28 días) de lechadas de cemento reforzadas con bentonita, cenizas volantes y humo de sílice. Se diseñaron los experimentos de acuerdo con un arreglo ortogonal tipo L16 en el que se contemplaban tres factores: la bentonita (0, 0,5, 1 y 3%), las cenizas volantes (10, 20, 30 y 40%) y el humo de sílice (0, 5, 10 y 20%) (porcentajes en peso del sólido). Los datos obtenidos se analizaron con mediante ANOVA y el método de Taguchi. De acuerdo con los resultados experimentales, el contenido tanto de cenizas volantes como de humo de sílice desempeña un papel significativo en la resistencia a compresión. Por otra parte, las condiciones óptimas que se han identificado son: 0% bentonita, 10% cenizas volantes, 20% humo de sílice y 28 días de tiempo de curado. La resistencia a compresión máxima conseguida en las anteriores condiciones era de 17,1 MPa

A critical evaluation of predictive models for rooted soil strength with application to predicting the seismic deformation of rooted slopes

This paper presents a comparative study of three different classes of model for estimating the reinforcing effect of plant roots in soil, namely (i) fibre pull-out model, (ii) fibre break models (including Wu and Waldron’s Model (WWM) and the Fibre Bundle Model (FBM)) and (iii) beam bending or p-y models (specifically Beam on a Non-linear Winkler-Foundation (BNWF) models). Firstly, the prediction model of root reinforcement based on pull-out being the dominant mechanism for different potential slip plane depths was proposed. The resulting root reinforcement calculated were then compared with those derived from the other two types of models. The estimated rooted soil strength distributions were then incorporated within a fully dynamic, plane-strain continuum finite element model to assess the consequences of the selection of rooted soil strength model on the global seismic stability of a vegetated slope (assessed via accumulated slip during earthquake shaking). For the particular case considered in this paper (no roots were observed to have broken after shearing), root cohesion predicted by the pull-out model is much closer to that the BNWF model, but is largely over-predicted by the family of fibre break models. In terms of the effects on the stability of vegetated slopes, there exists a threshold value beyond which the position of the critical slip plane would bypass the rooted zones, rather than passing through them. Further increase of root cohesion beyond this value has minimal effect on the global slope behaviour. This implies that significantly over-predicted root cohesion from fibre break models when used to model roots with non-negligible bending stiffness may still provide a reasonable prediction of overall behaviour, so long as the critical failure mechanism is already bypassing the root-reinforced zones. © 2019, The Author(s)

“The Future Market and the Current Reality”:Zaimoglu/Senkel’s Black Virgins and Interculturalism in the German Context

What happens to the relationship between theatre and interculturalism in a contemporary European country of immigration? How does making “intercultural theatre” differ from making theatre in an “intercultural society”? This chapter explores these questions with reference to the emergence of “postmigrant theatre” in Germany, and particularly Feridun Zaimoglu and Günter Senkel’s Black Virgins (Schwarze Jungfrauen). This controversial semi-documentary play about Muslim women premiered to great success in 2006 and has since appeared in at least ten further professional productions in Germany alone. Focusing on productions in Bremen, Hannover, and the Ruhr area, I situate this proliferation against a broader background of “interculturalism” in cultural policies within Germany, tracing the way in which intercultural policies have both enabled and demanded the production of new forms of engagement with postmigrant theatre. The title quotation, taken from the play, suggests an awareness of the uneasy positioning of the play’s success between market demands and a more rights-based approach to inclusion and recognition in contemporary Germany. A focus on the dynamics of intercultural policies allows us to unpack this positioning further, and explore what the production histories of Black Virgins have to tell us about interculturalism and performance in the German context and beyond

Engineering properties of sand stabilised with borogypsum

This paper investigates the use of borogypsum in modification of the engineering properties of granular soils. In this study, a poorly graded sand sample was stabilised with borogypsum waste, varied in content between 10% and 40%. Standard Proctor compaction, unconfined compressive strength (UCS), California bearing ratio (CBR), direct shear, freeze–thaw cycles and hydraulic conductivity tests were conducted on stabilised and unstabilised sand samples. The test results indicated that the addition of borogypsum to sand caused an increase in the optimum water content and maximum dry density. The UCS, CBR and cohesion intercept values were found to increase with increasing borogypsum content. However, the shear strength angle and coefficient of hydraulic conductivity decreased with increasing borogypsum content. The mass loss values after freeze–thaw cycles were found generally to be at a desirable level for sand–borogypsum mixtures. </jats:p