Numerical Study of Heat Transfer and Contaminant Transport in an Unsaturated Porous Soil

Penetration of chemicals in the soil ground through irrigation water or rainfall induces important risks for the environment. These risks are badly known and may lead to direct contamination of the environment (atmosphere or ground water) or harmful effects on organisms living at ground level, indirectly affecting men. It is thus necessary to estimate these potential chemical risks on the environment. For that reason, the gradual change of these products (fertilizers, solutions, pollutants, ...) in the ground has been the subject of a lot of recent research works, based in particular on the study of non-saturated porous media in a theoretical, numerical or experimental way. Most of these works are incomplete and, in order to simplify the problem, they don’t take into accounts some process, which may be of prime importance under particular natural conditions. Complexity of such studies results from their multidisciplinary nature. In this communication, we study simultaneous transport of pollutant, the water that provides transport and the heat transfer in a 200 cm long cylindrical column full of sand taken as a non-saturated porous medium. We consider two kinds of conditions on the temperature at the column surface: the case of constant temperature and the case of sinusoidal temperature. We evaluate the influence of this temperature on the transfers. This study is purely numerical. We use the control volume method to determine hydrous, thermal and pollutant concentration profiles.

Towards Include Preservation of Vitamins in Fenugreek and Carob Seeds by the Instant Controlled Pressure-Drop Process (DIC Process)

Fenugreek and carob seed were germinated in the dark for 4 days and 15 days respectively. The two species are rich in vitamins A, B1, B3, B8. Germination promotes the increase in their concentrations. To ensure preservation and increased bioavailability of the vitamins, it is necessary to apply a DIC of 30s to 400 kPa making it possible to support the cellular expansion and the decontamination of germinated seeds. Vitamin A content in germinated carob seed increased by 82.54%, which is not the case for fenugreek. A decrease in vitamin A concentration of 4 μg/100 g of dry matter. DIC increase vitamin B1, B3 and B8 in germinated fenugreek seeds. A slight decrease of B vitamins in germinated carob seed after treatment with DIC has been noticed. This loss can be explained by the low bioavailability caused mainly by the botanical structures of the seeds.

Physico-Mechanical Characterizations of Sand Concrete: Prestressed Beams and Hollow Bricks

The use of the sand concrete makes it possible to carry out a concrete having physico-mechanical properties answering the structural exigences and having economic and environmental advantages compared to the classical concrete. The present study aims to connecting the parameters of a formulation based on an empirical formula of Caquot in order to optimize, on the one hand the couple compressive strength/absorption of water under various degrees of hygrometry, and on the other hand more precisely to use the concrete sand in the public works sector in the prefabrication of prestressed beams and hollow bricks. The results show the importance of the type of formulation used because it takes into account the percentages of fillers of sand which is a co-product (waste) of massive rock crushing. In addition, the use of fillerized sands, which are wastes of crushing basaltic rocks and containing a small percentage of fillers, is efficient in the manufacture of prestressed beams. As for the hollow bricks, a fillerized basalt sand, containing a high percentage of filler, as well as a sand dune, gives satisfactory results.

Economic Feasibility Evaluation of Building Passive Houses

The research presents an improved method of rational design of energy-efficient low-rise residential buildings according to their life cycle. The mathematical model for finding the optimal version of draft power-efficient residential building has been developed. For conditions of Ukraine the optimization problem has been set and solved （finding the optimal version of the draft energy-efficient buildings）. The calculations prove the fact that the construction of passive houses in Ukraine today is economically feasible. Scientific and practical regulations, outlined in the research, can be used by all participants of the investment programs, and energy-efficiency projects, renovation projects and developing normative-technical documents.

农产品可控瞬时压差加工技术研究进展

可控瞬时压差加工技术(Instant controlled pressure drop processing,法语为Détente instantannée contr?lée,简称DIC),又称变温压差膨化技术,于1988年由法国学者发明。DIC加工技术的原理是基于将处理仓内高压(或大气压力)瞬时下降到真空状态,利用这一过程中产生的热力学效应使物料内部水分快速闪蒸,实现体积膨胀或质构改性等目的。经DIC技术处理后的农产品可获得多孔的组织结构和酥脆的口感。此外,DIC技术的优点还体现在色泽、风味,以及较低的生产成本等方面。本文综述了国内外可控瞬时压差加工技术的研究和应用现状,重点介绍了DIC在农产品质构改性、化学成分提取、杀菌消毒、食物脱敏、粮食干燥过程减损、生物能源制造、生物大分子改性和农产品干燥等方面的研究进展,分析了国内可控瞬时压差加工技术存在的主要问题,并对该技术未来的发展趋势进行了展望。