The aim of this paper is to provide a comprehensive mathematical model to describe the supercritical fluid extraction of vegetable oils. The complexity of the plant solid matrix structure, the effect of size, controlling effect of phase equilibrium, interaction between solute and solid matrix have been taken into account as well as axial dispersion in fluid phase. As two new attempts, profile of concentration for the inner region of particle along with concept of free solute on the surface of the particle was considered and equilibrium concentration dependence on concentration of free solute was presented. Obtained differential equations are partial and solved numerically. The ability of the model to predict the extraction yield was checked out under changing operating parameters of solvent flow rate, pressure, temperature and particle size, for the extraction of neem seed oil that percentage of sum of squared differences (SSD%) between the model prediction and the experimental data obtained 1%, 0.4%, 0.3% and 0.3%, respectively. Also for the extraction of sunflower seed oil, the effect of solvent flow rate was investigated that the SSD% was obtained 0.5%.

The main objective of this work is to propose a mathematical model for the differential sticking coefficient of clayey drilling Fluids with a lubricant as an additive and evaluate the influence of differential pressure and lubricant content on filter cake thickness and permeability. Tests were carried out on Fluids composed of water and 4.86% of active bentonite clay prepared in Hamilton Beach agitators at a high rotation speed (17000 rpm) for 20 minutes. After a 24-hour time-out in a closed container, lubricants were added to the Fluids at different levels. To obtain the differential sticking coefficient (DSC), and the filter cake, a differential sticking tester by Fann with a spherical torque plate was used, and the filter cake thickness was determined in an extensometer. The setting time, differential pressure, and lubricant content were defined as the input variables (independent variables) to the DSC mathematical model. The differential pressure and lubricant rate were the independent variables to the mathematical model of filter cake thickness (FCT) and permeability (K), which varied according to a factorial planning, was known as a second order model. The experimental data regression was performed utilizing Statistic software, version 7.0. The results clearly showed that it was possible to obtain a statistically meaningful and predictive mathematical model for DSC. It was also observed that the increase in the lubricant content was responsible for a DSC value reduction due to the fact that the lubricant was a dispersing agent reducing the filtrate volume and the filter cake thickness, and thereby decreasing the sticking risk due to differential pressure. Finally, from the analysis of point values and response surfaces for FCT and K, it was possible to observe tendencies that made clear that the differential pressure and lubricant content influenced filter cake properties.

A cold room assisted vapor-compression refrigeration cycle is dynamically modelled and optimized. The design parameters are evaporator pressure, condenser pressure, length, wall’ thickness and height of cold room, mass flow rate of refrigerant as well as the value of superheating/subcooling in evaporator/condenser. To find the optimum value of design parameters Multi Objective Genetic Algorithm (MOGA) is applied. Moreover three refrigerants included R22, R134a and R407c are used as working refrigerant in this system. Total annual cost (TACO) and coefficient of performance (COP) are selected as two objective functions. The optimum solutions show that R407c is the best refrigerant in both thermo dynamical and economical view points with 9148. 2 $/year as total annual cost and 6. 12 for COP. The optimum result of R407c showed the total annual cost improved 50. 74%, and 8. 68% in comparison with R134a and R22 respectively. Furthermore, COP improved 9. 97% and 13. 72% in comparison with R134a and R22, respectively. It is worth mentioning the optimum results reveal the compatible between two objectives, the coefficient of performance and the total annual cost (in maximum point of COP have minimum point of TACO). However by using R407c as refrigerant of system have the minimum area of cold room, the refrigerants R134a and R22 are in the next ranking, respectively.

Background and Aim: In patients with complete denture, some clinicians have used modelling plastic impression compound (MPIC) along tissue conditioner (TC) materials simultaneously. Little information is available on the composition of these materials and the interaction between them. The purpose of this study was to evaluate the influence of two components of MPIC on the structure and chemical composition of TC.Materials and Methods: In this experimental study, MPIC specimens were provided in 25×2 mm discs. Specimens were randomly divided into three groups and were immersed in ethanol 70%, plasticizer (dibutyl phthalate) and a mixture of them (ethanol 70% and dibutyl phthalate). All of the discs were weighed with a digital balance before and 2, 4, 6 and 24 hours after immersion. Values were analyzed by non parametric Kruskal-Wallis (a= 0.05) and SPSS 16 for Windows (SPSS Inc., Chicago, IL) was used for statistical analysis.Results: Statistical analysis indicated significant differences among all groups (p>.05).Conclusion: Dibutyl phthalate (DBP) had high impact on the solubility of MP, while the mixture of dibutyl phthalate (DBP) and ethanol demonstrated the highest impact.

Background and Aim: There are different methods of oral health education for child population. Theater show is a method that has not received enough attention until now. The aim of this study was to evaluate the effect of using theater show on dental health education in Yazd female elementary students.Materials and Methods: This was a quasi experimental study performed by using pre- and post-test method in Iran over the year 2004. One elementary school from each region of the city was selected. Twenty students from each grade of each school were included in the study (n=200). The information on knowledge, attitudes and practice of oral health were collected by using a valid and reliable questionnaire before and after theater show performance. Data were analyzed using SPSS and Wilcoxon signed rank test.Results: This study showed that the theater show could improve knowledge, attitude and proper oral health practice of children. The effect of the theater show on knowledge was more than attitude and was more on attitude than practice (P<0.001). Only literacy on the part of mothers was significantly correlated with practice (P=0.021). There were significant correlations between Knowledge (P=0.020), Attitude (P=0.0001) and oral health Practice (P=0.022) with students' grade level.Conclusion: This study showed that using theater show for oral health education, could improve the oral health related knowledge, attitude and proper oral health practice by elementary school students.

Different types of contact, including contact between node pairs, any-contact of nodes, and contacts of the entire network, are used to characterize social relations in mobile social networks. Different modes of routing, from the point of view of message delivery semantics, encompass unicasting, multicasting, any-casting, and broadcasting. Studies have shown that using probability distribution functions of contact data, which is mainly assumed to be homogeneous for nodes, improves the performance of these networks. However, there exists an important challenge in studies on distributions. A lot of works apply the distribution of one type of contact to other types. Hence in routing applications, it causes to use of the distribution of one type of contact for any mode of routing. This study provides a complete solution to model each type of homogeneous contact data distribution and to use them in different modes of routing. We propose a routing algorithm that uses this new model. Results show that our solution improves the average latency of comparing methods Epidemic, TCCB, and DR about 3.5-times, 30%, and 45%, respectively. It achieves a delivery rate of about 5% and 6%, and average latency about 6% and 8% better than that of DR and TCCB, respectively.

The present experimental study reports on enhancement of heat transfer by addition of nanoparticles to the working fluid of commercial swimming pool heat exchangers under laminar flow condition. Three different concentrations of Titanium dioxide nanoparticles were added to the water as working fluid of a typical forced convective heat exchanger used to transfer heat to public swimming pools. The experimental setup is capable of measuring velocity, heat transfer rate, and temperature at different points. TiO2 nanoparticles with mean diameter of 20 nm were used. The effects of suspended nanoparticles concentration and that of Peclet number on forced convective heat transfer were investigated. It is observed that at 0.1%, 0.5% and 1% weight concentration of suspended TiO2 nanoparticles, the average convective heat transfer coefficient improved by 1.1%, 15.9% and 31.6% respectively. The coefficient is further increased at higher Peclet numbers. The efficiency of heat exchanger is evaluated for different scenarios.