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Ground skidding on skid trails affects the physical properties of soil. The objective of this study was to evaluate changes in soil physical properties on skid trails formed due to traffic of metal-tracked skidders with regard to soil bulk density, total porosity, water content and penetration resistance. The studies were implemented on two levels of slope – <20% (SC1) and >20% (SC2) – and three levels of traffic (one, five and nine traffic cycles). The treatment plots with three replications, consequently, were 6 m long and 4 m wide. The measurement of soil penetration resistance was carried out using a cone penetrometer. The samples were taken from 10 cm of top soil at six points in each plot. The results indicated that the skidder traffic did not significantly affect the soil physical properties measured in three levels of traffic at SC1, whereas it was significant between one and five traffic cycles in SC2. Most of the changes in the measured properties in the skid trails occurred after the first loaded skidder traffic. Within all traffic of SC2, differences in the mean values of water content and soil porosity were greater compared with the mean values at the same traffic of SC1, although these differences were not significant. The bulk density and penetration resistance at five and nine traffics of SC2 were significantly different from the same traffic of SC1.

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The porosity of electrospun nanofibers web is a significant parameter affecting various areas of nanofibers applications. Thus, at first, the effect of most effective parameters, the concentration of polymer solution and flow rate, on the diameter of polyvinyl alcohol nanofibers, as a dissolving component, were investigated. Afterward, the hybrid web of polyamide 6/polyvinyl alcohol (PA/P) was prepared via a two-sided dual-nozzles electrospinning method. The morphology, diameter, pore size of nanofibers web and the effect of dissolving constituent were studied based on images of the scanning electron microscope. To measuring the porosity of nanofibrous webs, three practical and straightforward methods that have been proposed in the literature were utilized. It was observed that when one component was dissolved, the diameter of the resultant web was decreased, and the porosity has been reduced to about 70% based on the best selected method of porosity. Additionally, the average pore size of electrospun PA6 webs has been decreased about 30-58% relative to the original hybrid webs.

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Fermentation process of bread includes primary, middle and final sections. If dough is prepared by the traditional methods and immediately formed, in addition to the more energy consumption, the proper shape of dough will be affected and final product may have compressed texture, less porosity and specific volume and lower flavor and taste scores. Where the three section of fermentation performed, because of equal distribution of gas, more elasticity and formation and aromatic compound, the product has more porosity and taste and flavor. By considering the importance of this issue, the purpose of this study was the effect of primary fermentation time in three levels of 10, 15 and 20 minute, middle fermentation time on three levels of 5, 10 and 15 minute and final fermentation time on three levels of 25, 35 and 45 minute on crumb firmness, porosity, specific volume and sensory properties of Barbari bread. After comparing treatment with fully randomized factorial in p<0.05, the results showed the lowest firmness, the highest porosity and specific volume and the best score in sensory analysis was attribute to samples with primary fermentation time of 30 minute and final fermentation time of 45 minute. As compared to these treatments the greatest effect on improving the quality of Barbari bread was attributing to the sample with middle fermentation time of 10 minute.

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Coeliac is an autoimmune digestive disease that is caused by the digestion of gluten and the only treatment of this disease is a gluten-free diet. Therefore the acceptance and quality of gluten-free food production for these patients is important. So the aim of this study was evaluation of adding xanthan and guar gums (0, 0.3, 0.6 and 1%) on moisture content, specific volume, porosity, crust color (L*, a* and b* values) and sensory properties (overall acceptability) of sorghum gluten-freeoil cake. Also crust color and porosity were estimated and analyzed by Image J software. The results showed guar gum and xanthan gum especially combination of these gum were able to increase moisture, specific volume, porosity, L* value and overall acceptability in sensory evaluationof sorghum gluten-free oil cake. On the other hand addition of gums to oil cake formulation decreased the firmness of texture during 2hr and 1 week after baking. Also the best result was observed in sample containing 0.3% xanthan and 0.6% guar.  

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byatt@aut.ac.ir Abstract: Nowadays, several investigators pay attention to the rubble mounds among coastal structures due to their economic superiority over other types of in-shore structures and ease of construction in the marine environment. However, in order to guarantee a reliable design for such heavy structures, it is certainly necessary to have a sound understanding of the hydraulic nature of the unsteady- nonlinear flow's parameters controlling the rubble mounds response to the wave loadings. One of the basic uncertainties in determining hydraulic pressure gradient variations is known to be porosity of the media that should be estimated reliably. To cast light on the aforementioned issue, in the absence of up-to-date research works in the literature, a comprehensive investigation has been carried out in the Civil Engineering Department, Amirkabir University of Technology (Tehran, Iran). This paper reviews part of our research findings and points out that the conventional mathematical models for non-linear analysis of unsteady flow through coarse porous media are unable in precisely predicting the hydraulic gradient of flow within rubble mounds. The purpose of this paper is four folds: a. To study the state-of-the-art of mathematical modeling of the flow in coarse porous media: - Firstly, Carman-Kozeny mathematical model is investigated in the steady transient flow; - Secondly, the Forschheimer equation is investigated, where the second term shows the effect of turbulence (still) in steady flow; - Thirdly, a sound literature review is carried out to show the investigators’ view point on the third term that should be added to the Forschheimer equation to represent the impact of unsteadiness in unsteady non-transient flow in coarse porous media. b. To show the determining role of porosity in calculating the value of hydraulic pressure gradient: - After studying the distribution of errors amongst the parameters of the currently used mathematical models, it is shown that, to a large extent, an error in the value of hydraulic pressure gradient stems from the error in porosity. c. To show that mathematical models fail to determine correct values of Forschheimer coefficients: - The calculated values of Forschheimer coefficients are compared with the experimental results. - Discrepancies between the two values are shown on diagrams. d. To introduce the novel concept of effective porosity: - Effective porosity is introduced as the available space for the flow; - - In that sense, porosity should be determined not only based on geotechnical parameters but also it has to be regarded as a function of flow regime. It is also shown that contrary to the dominant opinion, which introduces porosity as a geotechnical property, it may be affected by flow regime through variations in the effective pore volume and effective shape factor. In a numerical justification of findings, it is shown that unsatisfactory results, obtained from non-linear mathematical models of unsteady flow, may be due to unreliable porosity estimates.

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  Gluten-freebakeryproductsisan important rolein the diet ofcoeliac diseaseandshould besupplied a part ofdailyenergy, protein,mineralsandvitaminsofthese patient's needs. Therefore the aim of this study was evaluation of adding BalanguShirazi gum (0, 0.25, 0.5, 0.75 and 1%) on moisture content, specific volume, porosity, crust color (L*, a* and b* values) and sensory properties (overall acceptance) of sorghum gluten-free semi volume Barbaribread. Crust color and porosity were estimated and analyzed by Image J software. The results showed the moisture content and L* value were increased by adding this gum. However the highest specific volume and overall acceptance in sensory evaluationwere observed in sample including 0.5% BalanguShirazi gum. On the other hand the lowest firmness (2hr after baking) was observed in this sample. Also the samples containing 0.25 and 0.5% BalanguShirazigum had the highest porosity and the lowest firmness (72hr after baking).  

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Today, withthegrowingpopulation andincreaseddemand for food production requires a high degree of community based and designed for industrial bread production line is felt. Preparing the dough by kneading and then dividing by hand could impact on the quality of the final product. So in this research one composite divider and rounder desigened and tested and compaired with piston dividing and rounding by conical rounder. The effect of this machine on texture, specific volume, color and total acceptamce of Barbari brrad was investigated. Results showed that dough injection by screw for dividing of Irainan loose dough was proper and could pereserve Co₂of dough. After dividing dough cylindrical rounder use for rounding. Finally the characteristics of bread bread mad from this machine and piston divider and conical rounder were compared. Results showed that in both treatments specific volume, texture and total acceptance had no significant diffrence. But porosity, L* and b* in teratment which made with piston divider and conical rounder were less and a* was higher in this system that can be one of the advantages of desigened machine in compare with piston divider and conical rounder.    

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In this paper, the normal flow permeability of an ordered fibrous structure, with square cross section is determined analytically. Porous structure is represented by a “unit cell” which is assumed to be repeated throughout the media. The selected unit cell is the space between four cylinders with square cross section. The analytical solution leads to a closed form equation for normal permeability of porous media including the geometrical parameters. Due to lack of experimental and analytical data for fluid flow through square cross section structures, a numerical study is also done and the obtained results are compared with the analytical solution. Moreover, a suitable scale analysis approach is employed to estimate the permeability of the fibrous structure. The presented method can predict the permeability of fibrous media, especially at high porosity. The present solution is successfully compared with the existing model in the literature over a wide range of porosity.

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This paper is concerned with the conduction heat transfer between two parallel plates filled with a multi-layer porous medium under a Local Thermal non - equilibrium condition. Analytical solution is obtained for both fluid and solid temperature fields in the porous channel incorporating the effects of thermal conductivity ratio, porosity, and a non-dimensional heat transfer coefficient at the pore level. The effects of the variable porosity on the temperature distribution are completely shown and compared with the constant porosity model. The presented method for analysis of heat transfer in a multi-layer porous medium is a generalized solution which is valid for arbitrary number of internal porous layers. The local temperature difference between fluid and solid phases is also calculated for a wide range of parameters. The results confirmed that the conductivity ratio and the porosity of the internal layers have significant role in the thermal modeling of the porous channel.

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Abstract- Unique properties of boron carbide (B4C) such as high hardness, low density, and comprehensive area for Neutron attraction, have turned this material into a very suitable candidate for many industrial applications such as nuclear facilities and light armored plates. According to inappropriate sinter ability of boron carbide, phenolic resin was utilized as sintered help for this ceramic. Different free additive samples of B4C with 5wt% phenolic resin were prepared and sintered at 2200°C. Then their physical and mechanical properties were investigated. Results show that the relative density of samples including 5wt% phenolic resin is equal to %95 and for samples without additive is equal to %82 of theoretical density. Furthermore, it can be seen an improvement in mechanical properties in comparison of free additives samples; so that the flexural strength from 264 to 318MPa, the modulus of elasticity from 445 to 465GPa, Vickers hardness from 3020 to 3150GPa and fracture toughness from 2.6 to 4.2MPa.m1/2 will be improved.

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According to theresearchersfocused onthe roleof bread in thenational economyandtheuse ofnaturaladditivesto reducestalingrateand improvethe quantitative and qualitativeproperties ofstrategic products, So The aim of thisstudy was to investigatethe effect ofdifferent levels ofwatermelon(0, 1, 2, 4, 8 and 16%) on dough farinographypropertiesandmoisture content, specific volume, porosity andfirmness of semi volume Barbari bread. Inthis study, Image J software was used for porosity measurement. The resultsshowed thatwith the increasing ofwatermelonin the bread formulation, water absorption anddegree of softening increased butthe amount of dough stability decreased. While the mostdoughdevelopment timewas observedinsamples containing2% water melon. Also theresultsshowed thatthemelon water as a natural additive canincreases the amountof moisture content,porosity andspecific volumeanddecreased firmnessoftexture. So the highest moisture, specific volume andporosity were observed in ofthesamplescontainedrespectively16, 4and8% water melon. It should be notedthatsamples containing4% water melonhadthe lowestfirmness.  

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In this article, the size, dimensions, volume, bulk and particle densities, empyting and filling angles of repose and friction coefficients against different surfaces were evaluated for two varieties of barley, Sahra and Valfajr, as a function of moisture content in the range of 10.12 to 42.17 (w.b.%). Most physical properties of barley varieties were significantly affected by moisture content variation. The length, width, thickness and unit mass of Sahra variety increased from 9.88 to 10.16 mm, 3.37 to 3.89 mm, 2.54 to 2.80 mm and 0.048 to 0.074 g, respectively, as the moisture content increased. The respective values for Valfajr varied from 8.37 to 8.87 mm, 3.03 to 3.21 mm, 2.21 to 2.37 mm and 0.037 to 0.043 g, respectively. In Sahra variety, sphericity, geometric mean diameter, bulk density, particle density and porosity increased from 44.59 to 47.40%; 4.38 to 4.79 mm; 568.10 to 613.68 kg m-3; 1,099.65 to 1,245.72 kg m-3 and 48.34 to 50.74%, respectively. The coefficient of static friction increased linearly against all the tested surfaces as the moisture content increased. In Valfajr variety, sphericity increased from 45.79 to 45.89%; geometric mean diameter increased from 3.82 to 4.06 mm; bulk density increased from 579.68 to 608.58 kg m-3; particle density varied from 1,410.82 to 1,230.61 kg m-3; porosity varied from 58.91 to 50.55% and the coefficient of static friction increased linearly against all the tested surfaces as the moisture content increased. The angle of repose for emptying and filling increased linearly as well.

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Abstract: The two main characteristics of a porous bed are the bed material diameter – representing its coarseness - and the porosity which represents its permeability. In this paper the effect of bed permeability on the average structure of flow turbulence is investigated. Flow is modeled using an innovativecontinuum approach based on Volume Averaged Navier-Stokes Equations in several different channel bed porosities. Results of four different simulations with various porosities are presented. Bed permeability can be represented by the permeability Reynolds number, Rek, which is the ratio of effective diameter of porosity and the length scale of eddies near the bed. The Reynolds permeability number (Rek) is the best expression for the bed permeability quantity. In small Rekthe bed acts as a solid/rigid boundary and in large Rek, the bed will behave as a high permeable boundary with negligible viscosity effects. Under these conditions, the turbulence eddies along the flow are rarely observable. The reasons can be due to: 1) the mechanism of free turbulence transfer through permeable layer and/or 2) a considerable decrease in the average shear stress due to no wall-blocking and low-viscosity effects. The dominant characteristic of turbulence near a high permeable bed is relatively large eddy structures, probably originating from so-called Kelvin-Helmholtz instabilities. Suchflow pattern with large vortexes leads to high momentum exchange between the free channel flow and the two-phase flow in porous media below permeable bed. This process also increases the friction between flow and the substrate and therefore will result in moving the Logarithmic-low region slightly downward. In addition, it is observed that the log-low cur near a high permeable bed is 4% steeper than in solid and rough bed.

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Presence of porosity and gas layers around the Al2O3 particles are one of the most important reasons of decreasing in mechanical properties of aluminum metal matrix composites. In this research, for decreasing of porosity, increasing of wettability and uniformly distribution of particles in matrix three method were used; using inert gas for injection powder with 5 liter/ min flow rate, particles heat treatment in 1100 ̊C for 20 min and mill Al2O3 particles with Al particles in ratio of Al / Al2O3= 1. The effect of these parameters on microstructure and mechanical properties of composite were investigated. The results showed that amount of porosity and agglomeration of particles were high in metal matrix composite with handy injection of particles. While injection with inert gas, using heat treatment and Al / Al2O3 milled Cause improve wettability and uniformly distribution of particles in molten Al. the results showed the maximum value of hardness , compression strength and impact energy have obtained in metal matrix composite reinforced with Al / Al2O3 milled with value of 78.7 BHN, 539.1 MPa and 8.2 Joule, respectively.

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Despite several studies and researches already carried out on secondary consolidation in fine-grain soils, there is no consensus among researchers about the changes of the coefficient of secondary consolidation versus stress. The present research specifically aims to discuss the trend of these changes in soils having double porosity and undergoing stress. The behavior of kaolin has been investigated un this work. Samples with a double porosity structure have been compacted. In order to make sure of the preparation procedure as well as the existence of double porosity in them, prosimetry experiments were also carried out by mercury intrusion method which finally confirmed the existence of double porosity structure in the samples. The samples were put in a consolidation apparatus. Saturation was done in two ways; the first group samples were saturated and then loaded. In the second group, the samples were loaded and then saturated under a constant load. The results indicate that the order of saturation process has no effect on the porosity of the samples after they have been saturated (Collapse). Over the long time of measuring the secondary changes in soil volume, the samples were put under a constant load, and value of increase in settlement versus time after the completion of initial consolidation was measured. The experimental data shows that in the stress range of 100 to around 300 kPa, the coefficient of secondary consolidation has had an increasing trend reaching its maximum and has descended after passing the 300 kPa. This result is in compliance with the past researchers’ results trend. So, given that the soil used by the past researchers has been of simple-porosity type, it can be inferred from the results of the present research that double porosity structure has no effect on trend of changes in secondary consolidation coefficient. The main purpose of this research is to present experimental data on the changes of coefficient of secondary consolidation under stress in an aggregated soil,. One-dimensional consolidation tests were performed and analyzed. The effect of net stress and initial porosity on changes in secondary consolidation coefficient was also studied. The paper is divided into four major parts; after the first part of the paper, introduction, the second part presents details of the experimental plan including characteristics of the soil under study, sample preparing technique, and experiment procedure (method of applying loads). Results and their interpretation are discussed in the third part, and finally, the main findings of the research are summarized in the fourth section. The tests indicated that path of collapse of structure and transposition of loading and saturation processes have no effect on porosity of sample after collapse at a certain stress value, and end of the primary consolidation line is a unique line.

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Electrochemical supercapacitors store energy in the electric field formed at the interface of electrode/electrolyte in the electrochemical double layer. Compared to conventional capacitors, using high surface area electrodes results in the extremely large capacitance in supercapacitors. A mathematical model has been developed to investigate the effect of electrode thickness and porosity on the performance of double-layer supercapacitor. The model is based on the conservation of specious and charge governing equations. This model drops the common simplifying assumptions of concentrations uniformity and capacitance independence of voltage in supercapacitors models. The model can predict the experimental data of cell voltage with high accuracy and is used to examine the effect of utilizing different electrode thicknesses and porosities on the performance. In the design and operation condition of supercapacitor considered here, specific capacitance increases as electrode thickness increases for electrode thicknesses from 70 to 90 micrometer and decreases as electrode thickness exceeds from 90 micrometer. Employing more porous electrodes enhances specific capacitance. The amount of increment is such that if the electrode porosity is doubled, specific capacitance increases by approximately 5%.

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The food researchers look to offer products with low- fat because of increasing awareness about health. In this project, low-fat composite (wheat-quinoa) cup cake was produced. Plantago major L. gum and water (1.5-7.5, 3-15, 4.5-22.5 and 6 -30%) was used as a fat replacer in levels of 0, 25, 50, 75 and 100 % in wheat-quinoa cake by completely randomized design. The samples containing 1.5 and 3 % gum had the lowest specific gravity and the highest porosity. Also, the highest consistency was indicated in the sample containing 3 % gum. On the other hand, the sample containing 3 % gum had the lowest firmness in 2 hours and 1 week after baking. This sample had the coherent micro structure. Finally, the samples containing 1.5 and 3 % gum had the best overall acceptability. Therefore, it can be said that the removal of 50% of oil in cake formulation was performed successfully.

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Lost foam casting is a new method for casting complex parts. This method, in addition to its technical and economic advantages over the traditional methods, has environmental benefits and therefore has been of special interest. In this study, the effects of foam density, pouring temperature, and coating viscosity were studied, which are the most important factors affecting porosity and hardness in the lost foam casting method. The Taguchi method, signal to noise ratio and analysis of variance were used to design experiments and determine the optimal levels of each variable. All the considered variables were evaluated in three levels using L9 orthogonal array Taguchi analysis. Results showed that foam density of 20 kg/m3, pouring temperature of 740° C and coating viscosity of 20 sec were the optimal values for the variables due to creating appropriate condition between thermal decomposition and foam evaporation with speed of melting advancement and exhaust gas through the pores in the coating and creating lowest porosity (2.6%) and highest hardness value (27.7 HRA). Foam density and pouring temperature were the most influential parameters on the porosity and hardness with the impact factors of 64.58% and 56.35%, respectively.

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 Jujube is a functional fruit with a great source of fibers, vitamins and nutritional elements and has a sweet, delicious flavor. Replacement effects of wheat flour with varying levels of jujube powder (0, 5, 15 and 25 % w/w) on the physicochemical, texture and sensory properties of the cakes based on completely randomized design, was investigated. The viscosity of cake batter increased from 744.5 cp (% 0 jujube powder) to 9872.5 cp (% 25 jujube powder) as the replacement level of wheat flour with jujube powder increased (p <0.05). The physicochemical (moisture content, volume, porosity, firmness, fiber and ash) and sensory properties of the cake prepared by replacing wheat flour with jujube powder were changed significantly (p <0.05). As the replacement level of wheat flour with jujube powder increased, the volume and porosity of the cake were decreased and the hardness, fiber, ash, browning index and the lightness of them were increased (p <0.05). Cakes made with the % 5 and then the higher level (up to % 15) as compared to control, received the highest sensory overall scores (p <0.05).  The cakes containing % 5 jujube powder, showed the least physicochemical changes similar to control samples and found to be more acceptable from sensory points as compared to other treatments (p <0.05).