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Compression stiffened panel are the reinforced skins that are mainly subjected to axial compressive load and widely used in aerospace structures. Iterative design loops are the common methods for this type of structures. Design methodology based on structural index concept is a coupled design and analysis method. In this method detail design of the compression stiffened panel is fully accomplished based on the key parameters of structural index and material properties of the panel. The complete design is obtained in single stagein a analytical and explict manner. In this paper the design methodology of stiffened panel using structural index concept is analyzed that could be applied on selective configuration of compression stiffened panel (including selection of stiffener type and the type of the panel: integral or skin-stringer ones). The results extracted and modified from two different approaches to cope with the results of common iteration methods that currently used in the preliminary sizing of stiffened panel. This procedure could be regarded as a near optimum design and therefore would be more conservative with respect to common methods. Final results of the derived methodology are compared with reported and F.E.M results. The results could be regarded as an acceptable design further more they can be used as appropriate starting point in numerical optimization methods.

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In the present paper, the results of an approximation method named structural index used as the first step, the process of design and optimization of stiffened panel with Gaussian type surrogate model are carried out. Modeling phase is based on the finite element analyses of the structure. Nonlinear buckling load is set as the design constraint. The surrogate model is employed to reduce the number of finite element analyses in the optimization process. Therefore time of design process is reduced. Using infill points in the modeling and optimization process, converging to local optima is ensured. Introducing a novel technique, finding the global optimum of the surrogate model is guaranteed. The approach of surrogate based optimization is illustrated using two test problems. Also the sensitivity of the response to the initial sampling plan is investigated. Convergence criteria usually used in surrogate based optimization is modified to speed the convergence but is not affected the quality of the response. Design optimization process is presented for two types of stiffened panels. In type 1 stiffened panel with 4 design variables, the initial training set is constructed using 55 points. The response is obtained after addition of 5 infill points. For type 2, the initial sampling plan is selected to be 58 points. The optimization process is stopped after adding 173 infill points. Finally, obtained results are compared with the results of structural index method and an approach toward global optimum of the compression stiffened panel is introduced with the characteristics of optimum structure.

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This research was carried out to study the antifungal effect of aqueous extract and powder of Pistacia atlantica at 0, 0.5, 1, 2.5 and 5% on the growth of Aspergillus flavus and Aspergillus niger. Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) of the baneh extract and powder was certified against Aspergillus niger and Aspergillus flavus in concentrations of 0.5, 0.4, 0.3, 0.2, 0.1 and 0.05 g /ml were determined by Serial Dilution technique. After preparing lactic cheese samples, a 10 mm piece was placed inside the plate and 3 μl Aspergillus flavus and Aspergillus niger was added to its center. Plates were incubated at 26 ° C for 3 weeks and the zone diameter of mold growth was measured. The results showed that by increasing the storage period, the growth zone diameter of Aspergillus flavus and Aspergillus niger in all of treatments increased. The treatments had a greater effect on the control of Aspergillus flavus mold growth than that of Aspergillus niger in lactic cheese. In mold and yeast counting, the highest count was observed for control treatment and the lowest increase was related to treatment containing 5% extract of Pistacia atlantica. The experimental treatments also significantly affected the sensory properties of the cheese samples. The highest taste scores were for samples containing 0.5 and 1% Pistacia atlantica extract. The samples containing more levels of extract (2.5 and 5 %) were less scored in terms of flavor and taste than those containing powder of Pistacia atlantica. From the findings of this study, it can be concluded that extracts and powder of Pistacia atlantica have an appropriate antifungal activity against Aspergillus niger and Aspergillus flavus, Therefore, they can be used in medical pharmacology, food industries and health affairs as drugs and anti-fungal elements.

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In this study, the hydrostatic vibration analysis of an isotropic rectangular microplate in partial contact with a bounded fluid is studied. Modified couple stress theory based on the Kirchhoff plate assumptions are used to mathematically model the problem. The extended Hamilton’s principle is employed to drive the governing differential equation of motion and the corresponding boundary conditions. The transverse displacement of the microplate is approximated by a set of admissible functions which must satisfy the geometric boundary conditions. The fluid is assumed to be incompressible, inviscid and irrotational and the fluid velocity potential is obtained using the boundary and compatibility conditions. Natural frequencies of the microplate are calculated using the Rayleigh-Ritz method. To validate the present results, the natural frequencies of an isotropic macroplate in contact with fluid are compared with the available data in the literature and very good agreements are observed. Finally using the numerical data, the effect of different parameters such as thickness to length scale parameter, aspect ratio, length to thickness ratio and boundary conditions on the natural frequencies of the microplate are discussed in detail. We have observed that the difference between the natural frequencies predicted using the classical theory and the one evaluated by the modified couple stress theory is significant when thickness of the microplate is small, but diminishes as thickness increases.

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The aim of this study was to investigate the effect of microencapsulation of probiotic bacteria with sodium alginate/resistant starch and sodium alginate/chitosan by extrusion method on qualitative and rheological properties and viability of bifidobactrium animalis subs lactis in Aloe vera doogh. 10% of aloe vera gel with different concentrations of whey (5, 10 and 15%) and inulin (0.5, 1 and 1.5%) added to probiotic doogh and their effect on the protection of Probiotic bacteria and qualitative properties were evaluated. The results showed that increasing the level of inulin had no significant effect on pH. Increasing the percentage of whey up to 5% had no significant effect on the pH, but increasing more than 5% significantly decreased the pH of the doogh samples during storage period. In terms of sensory properties samples containing 1% inulin and microencapsulated bacteria with sodium alginate/chitosan had highest scores in flavour while lowest score was observed in control treatment (without inulin and whey) and free bacteria. Doogh samples containing 1.5% inulin had the lowest serum separation and the control sample (without inulin and whey) showed the highest serum separation at the end of storage period. In general, samples containing microcapsules had a lower serum separation than samples containing free bacteria. The highest viscosity and consistency coefficients were observed in the doogh samples containing 1.5% inulin. The microencapsulation process increased the apparent viscosity, consistency index and loss modulus and decreased the flow behavior index of the doogh samples. Microencapsulation of probiotic bacteria by sodium alginate / resistant starch and chitosan and use of whey and inulin in doogh samples increased their viability during storage period.

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In recent years, the tendency to use antimicrobial films and coatings has increased, which has increased the quality, safety and shelf life of food. In this study, basil seed mucilage coating containing different concentrations of Caraway extract (0, 1, 2.5 and 5%) was used to increase the shelf life of lactic cheese. Cheese samples were subjected to various microbial, physicochemical and sensory tests. The results of physicochemical evaluation showed that with increasing the storage period, moisture content and pH decreased and acidity increased in all coated cheeses. Sensory evaluation of lactic cheeses showed that the aroma, taste and overall acceptance of coated cheeses containing lower concentrations of Caraway (1 and 2.5%) were better compared to the control sample, while in coated cheeses Containing high concentrations of the extract (5%) due to the negative effect of Caraway extract on the organoleptic properties of cheese, the overall acceptance was significantly reduced. Coating with basil seed mucilage and Caraway extract significantly reduced the total count of bacteria and molds compared to the control sample.  Also, the total microbial count and the number of mold and yeast in all samples increased over time and this increase was more in the control sample. In general, it can be concluded that the oral coating of basil seeds mucilage containing Caraway extract can be used in food packaging systems, especially for lactic cheese.

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This study was performed to evaluate the different levels of celery puree on the physicochemical properties and viability of probiotic bacteria in yogurt. The results showed that at the end of the storage period, the highest pH was observed in the sample containing 10% celery. With increasing the storage period, the acidity increased and the highest and lowest acidity at the end of the storage period was observed in control and treatments with 10% celery, respectively. Yogurt samples containing 10% celery showed the lowest serum separation rate and control samples showed the highest. In the case of sensory properties, treatments with 10% celery obtained the highest scores of taste, odor, texture and general acceptance. The highest and lowest color scores were related to the treatment containing 5% of celery and control, respectively. Evaluation of rheological properties showed that in all samples, the viscosity decreased with increasing shear rate and samples containing 10% celery have a higher viscosity than other samples. At the end of the storage period, the highest vaiability of probiotic bacteria was observed in yogurt samples containing 10% celery. According to the results of this study, probiotic yogurt containing celery can be introduced as a useful product due to its desirable sensory and probiotic properties.

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The aim of this study was to compare the vacuum production of barberry (Berberis vulgaris)  leather with traditional heating methods. Three formulas with different levels of barberry (47, 72 and 92%) were prepared and their quality properties were investigated. The results showed that pH decreased with increasing the percentage of barberry puree in the formulation. With increasing the percentage of barberry puree in the formulation, the amount of elongation and tensile strength increased. Drying method did not show a significant effect on elongation and tensile strength (p> 0.05). In terms of sensory properties, samples containing 72% of barberry received the highest flavour score. With increasing percentage of barberry puree in the formulation, odor, color and texture scores increased and the samples dried by vacuum method had more odor, color and texture scores than samples dried in the traditional method. The type of drying method had not a significant effect on texture score of leather samples (p> 0.05). With increasing the percentage of barberry puree in leather formulation, the amount of total phenolic compounds and antioxidant activity increased in both drying methods. With increasing storage period, the number of mold and yeast and bacteria increased. At the end of the storage period, the lowest total microbial count was observed in samples containing 92% of dried barberry puree under vacuum and the highest count of mold and yeast in samples containing 47% of dried barberry puree with traditional method was observed.

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The composition and properties of edible coatings significantly affect their effects on food preservation. In this study, the effect of edible coating of sodium caseinate with different levels of inulin (0, 1, 2.5 and 5%) on the physicochemical, microbial, rheological and organoleptic properties of lactic cheese was investigated. The studied cheeses were produced in Pegah milk factory. Treatments included five groups: control (uncoated), sodium caseinate, sodium caseinate with 1, 2.5 and 5% inulin. The results showed that with increasing the storage period, the pH and moisture content decreased and the acidity of the samples increased significantly. The highest and lowest moisture content were related to the treatment coated with sodium caseinate and 5% inulin and the control treatment, respectively. In evaluating the organoleptic properties, the effect of the studied treatments on all organoleptic properties, except odor and color, was significant. The highest taste score was related to the treatment coated with sodium caseinate and 1% inulin and the lowest taste score was related to the control and the treatment coated with sodium caseinate and 5% inulin. As the storage period increased, the hardness, cohesiveness and chewiness of the samples increased. At the end of the storage period, the highest hardness was observed in the control and the lowest hardness was observed in the sodium caseinate treatments with 5% inulin, which was not significantly different from the sodium caseinate with 2.5% inulin. With increasing storage period, microbial count increased and the highest total microbial count and mold and yeast were related to the control and the lowest amount was related to the treatment coated with sodium caseinate and 5% inulin. In general, the use of edible coating of sodium caseinate and inulin improved the appearance and prevented textural changes and reduced the microbial activity of lactic cheese during the storage period.
 

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Key lime juice can be a non-fermenting product with high acidity and a rich source of ascorbic acid and phenol compound. In order to maintain the quality of the product, it is important to choose a suitable method for processing this food.
The use of modern non-thermal methods to produce high quality products should be considered. In this research, by designing and constructing a continuous pulsed electric field (PEF) system, the effect of this method on the degradation of pectin methyl esterase (PME), ascorbic acid, total phenol compound, cloudiness index, color changes and sensory evaluation in key lime juice is discussed. In this research, a bipolar square wave of 10 microseconds and a constant frequency of 1000 is used. In the processing chamber of this device, two cases of stainless steel with length and thickness of 10 and 0.5 ml, respectively, were used. Key lime juice was processed for 500, 571, 666, 800 and 1000 microseconds with Field intensity of 22.22, 33.33, 44.44 and 55.55 kV per cm. In general, by increasing the field from 22.22 to 55.55 kV / cm at a constant time, the process of reducing the degradation of PME enzyme is normally increased by 25%. Applying the highest electric field of 55.55 in 1000 microseconds caused 14% ascorbic acid degradation compared to fresh samples. With increasing pulsed electric fields, the cloudy index of the sample and browning index have increased. The use of high intensity pulsed electric field increased the degradation of PME enzyme and the cloudy index and reduced lightness compared to the fresh sample. Preservation of sensory properties of key lime juice developed with PEF during shelf life showed that the non-thermal pulsed electric field method can act as a promising approach in products with high acidity and enzyme degradation.