排序方式: 共有17条查询结果,搜索用时 31 毫秒
1.
Lamine Hassini Roman Peczalski Pierre Laurent Soufien Azzouz 《Drying Technology》2015,33(15-16):1872-1882
The aim of this work was to simulate in two-dimensions the spatio-temporal evolution of the moisture content, the temperature, and the mechanical stress within a highly deformable and water saturated product during convective drying. The material under study was an elongated potato sample with a square section placed in hot air flow. A comprehensive hydro-thermal model had been merged with a mechanical model, assuming a viscoelastic material, a plane deformation, and an isotropic linear hydric-shrinkage of the sample. This model was validated on the basis of the average water content and core temperature curves for drying trials under different operating conditions. The material viscoelastic properties were measured by means of stress relaxation tests at different water contents. The viscoelastic behavior was described by a generalized Maxwell model whose parameters were correlated to water content. The simulations of the spatio-temporal distributions of mechanical stress were performed and interpreted in terms of product potential damage. The sample shape was also predicted all aver the drying process with reasonable accuracy. 相似文献
2.
Single‐Crystalline La0.7Sr0.3MnO3 Nanowires by Polymer‐Template‐Directed Chemical Solution Synthesis
3.
K. Guenachi A. Hamou N. Hassini Jean-Marc Saiter Stephane Marais E. Beucher 《Materials Research Innovations》2002,6(4):174-178
Sandwinds have been simulated with an apparatus developed in our laboratory. Infra red and UV visible spectroscopies, contact
angle and interferential microscopy investigations have been performed on untreated polyethylene film sample and on samples
submitted at 40 °C to a simulated sandwind for times up to 4 hours. The surface roughness is modified, leading to drastic
decrease of the ultra-violet visible light transmission. This phenomenon is due to the presence of small sand particles inlaid
in the sample surface and due to surface erosion. In the time range of our experiments, no chemical action due to the sandwind
is observed.
Electronic Publication 相似文献
4.
A mathematical model was developed to simulate in 2D the spatiotemporal evolution of the moisture content, the temperature and the mechanical stress within a deformable and saturated product during convective drying. A comprehensive hydro-thermal model had been merged with a Maxwell model with two branches, assuming a viscoelastic material, a plane deformation and an isotropic hydric-shrinkage of the sample. A long sample of clay mixture with a square section was chosen as an application case. The transport and equilibrium properties of the product required for the modeling were determined from previous experiments which were independent of the drying trials. In order to validate the hydro-thermal part of the model, several drying tests were carried out for different values of temperature, relative humidity and air velocity in a vertical drying tunnel (designed and constructed in the LETTM laboratory). The theoretical and experimental results appeared in good agreement. The simulations of the spatio-temporal distribution of mechanical stress were performed and interpreted in terms of product potential damage. The sample shape was also predicted all aver the drying process with reasonable accuracy. 相似文献
5.
Effects of seed priming,salinity and methyl jasmonate treatment on bioactive composition of Brassica oleracea var. capitata (white and red varieties) sprouts
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6.
Abdelmadjid Dobbi Ahcene Bouabdallah Mohamed Bouchama Faiza Zahira Meghoufel Noureddine Hassini 《Polymer Engineering and Science》2012,52(11):2304-2309
The effects of natural ageing, in sub‐Saharan regions, on treated low density polyethylene by cold plasma are presented in this work. The data analysis is performed by comparing the changes of physical, mechanical and structural effects on the material surface induced by plasma treatment with regard to the natural abrasion effect due to sand wind. Plasma treatments for short durations are applied to neutral LDPE (low density polyethylene) films. Few seconds suffice to observe chemical changes on the samples. The treated samples are then subjected to natural ageing in the region of Ouargla (south of Algeria), characterized by very frequent sand wind. The characterization of the effects of plasma treatment and its combination with sand wind is performed using XPS (X‐ray Photoelectron Spectroscopy), FTIR (Fourier Transform Infrared spectrometry), and mechanical tensile testing. The results led to conclude a synthesis of new materials on the surface that significantly change the material surface properties and physico‐chemical properties of material, more particularly, optical, and mechanical properties are thus strongly affected. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers 相似文献
7.
Sahbi Ouertani Ahmed Koubaa Soufien Azzouz Rim Bahar Lamine Hassini Ali Belghith 《Holz als Roh- und Werkstoff》2018,76(4):1101-1111
The aims of this study were to determine (1) the effects of microwave irradiation on the drying kinetics of jack pine wood, (2) the phytosanitary efficacy, and (3) the processing energy consumption and mechanical strength of the dried product. Microwave drying experiments were performed at 2.45 GHz frequency and at microwave powers ranging from 300 to 1000 W. Results indicate that higher microwave power and initial wood temperature and lower sample thickness increases the internal sample temperature, improves the drying rate, and reduces both drying time and energy consumption. The microwave irradiation efficacy to sanitize jack pine wood boards was determined in terms of temperature/time combinations based on actual drying kinetics according to standards for phytosanitary measures. The energy required to dry 12 mm thick wood board samples at microwave power ranging from 300 to 1000 W was in the range of 36.4–12.3 MJ/kg of water, respectively, for up to 65% energy consumption savings. The impact of microwave power on the mechanical properties was not statistically significant, although mechanical properties tended to decrease with increasing power. 相似文献
8.
Sahbi Ouertani Lamine Hassini Soufien Azzouz Sadoth Sandoval Torres Ali Belghith Ahmed Koubaa 《Drying Technology》2013,31(10):1234-1242
The impact of microwave drying on the quality of dried wood remains unclear. Particular attention should be paid in order to optimize the combined microwave and convective drying process. In this study, a comprehensive internal heat and mass transfer model was developed and numerically implemented in order to simulate and understand the physical phenomena occurring inside Jack pine wood during a combined microwave and convective drying process. The model was validated on the basis of the average moisture content curves for drying scenarios at various microwave power levels. According to the simulations results, an increase in microwave power significantly decreases the drying time of Jack pine wood and increases its internal gas pressure, which increases the risk of cracking. However, compared to purely conventional convective drying, combined microwave and convective drying at medium microwave power and air temperature significantly reduces the drying time and maintains the internal gas pressure at reasonable values. At these conditions, the risk of cracking will be diminished. This last result was checked via experimental measurements of the sample strength dried at different microwave power levels. From this study, we can consider that for Jack pine wood, combined microwave and convective drying is a more efficient technology compared to classical convective drying. 相似文献
9.
Motivated by a real case of an automobile company, this study proposes a multi-objective, multi-site production planning model integrating procurement and distribution plans in a multi-echelon supply chain network with multiple suppliers, multiple manufacturing plants and multiple distribution centres. The model incorporates four important conflicting objectives simultaneously: minimisation of the total cost of logistics, maximisation of the total value of purchasing, minimisation of defective items and minimisation of late deliveries subject to some realistic constraints. Due to the imprecise/fuzzy nature of the objectives’ aspiration levels and some critical data, an interactive fuzzy goal programming formulation is first developed. Then, a novel fuzzy approach is proposed to convert the FGP model into an auxiliary crisp formulation to find an efficient compromise solution. The proposed model and solution method are validated through some numerical tests. Computational results indicate the practicality and tractability of the proposed model and also the superiority of the proposed auxiliary crisp formulation in contrast to the current alternative fuzzy approaches. 相似文献
10.
Given a set of storage spaces and a set of products, with specific space requirements and demand rates, we find the optimal product assignment that will lead to the longest time before any product is depleted. When demand rates are known with certainty, the assignment is found through the solution of a max–min integer program. When demand rates are stochastic with a common law, the assignment is found by solving an integer programme the objective of which is a non-homogeneous partial difference equation of first order. Unlike what common rules of thumb would dictate, our results show that the proportion of spaces assigned to a product is not necessarily equal to its demand frequency. Numerical computations show that employing the latter policy would result in inter-replenishment times that are about 24% shorter than the optimal solution. 相似文献