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In general, temporary well plugging is essential for repairing of oil and gas wells due to their long life time. One of the newest methods used for this purpose is gel polymer plugging. The strength of the gel in the well conditions is one of the most important challenges in the application of gel polymer in the temporary well plugging in work over operation. In this study, silica nanoparticles were used to improve the strength of polymer hydrogels. The bottle and rheological tests were used to determine the gel strength in desired well conditions (high temperature and high salinity). Also, the gel strength properties and swelling behavior were studied in various conditions such as distilled water, formation water, tap water and oil. It was observed that the strength of the gel increased from 520Pa to about 36kPa (5000% increase) by adding nanoparticles. Also, the gel swelling in the aqueous solution has been significantly reduced. Based on the results obtained in this study, a polymer gel containing 9 wt.% of silica nanoparticles with structural strength and thermal stability at 90 °C was introduced for field studies.

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Changes in pore fluid can significantly impact the geotechnical behavior of soil, especially clayey soil. One source of soil contamination is leachate, which can infiltrate nearby soil during the collection, transportation, and deposition stages of the residential waste disposal process, exerting geotechnical influences on the soil in the surrounding area. To assess these effects, four leachate samples were collected from different sites. The specimen comprises fine soil, created from a mixture of sand, bentonite, and kaolinite. Experimental results reveal a decreasing trend in the liquid limit, compaction parameters, and cohesion values of the soil with an increase in contamination level. However, the internal friction angle exhibits an increasing trend with higher leachate concentration, resembling the behavior of sandy soil, as opposed to the typical behavior of clay.

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Quasi-static compressive tests to determine the mechanical properties of individual brown rice kernels were conducted on whole kernel rice of Hashemi and core specimens of Khazar varieties. The magnitudes of the failure force, failure deformation, breakage energy and apparent elasticity modulus for Hashemi kernels were determined at two moisture content levels, namly, %11 and %17 (w.b.) at four levels of loading rates ranging from 1 mm/min to 5.5 mm/min. For the Khazar variety, the magnitudes of failure stress and strain, as well as toughness and elasticity modulus were determined at moisture content of %14 (w.b.) for five levels of loading rates ranging from 0.5 mm/min to 1.5 mm/min. Statistical analysis of the test results showed that deformation rates had no significant effect on the mechanical properties. Moisture content had a significant effect on all grain mechanical properties. Decreasing moisture content caused significant increases in all these properties. The failure force and the breaking energy for Hashemi kernels increased more than double, when the moisture content decreased from 17% to 11%. The magnitudes of failure force and breaking energy varied from 56 N to 115.7 N, and from 2.01 mJ to 5.23 mJ, respectively. The means of apparent elasticity modulus for compressive test on the core specimens was calculated to be 1.762 GPa at 17% moisture content and 2.835 GPa at 11% moisture content. Compressive strength and apparent elasticity modulus for Khazar variety were determined to be 36 MPa and 973.4 MPa, respectively. Some of the mechanical properties compared well with the published data.

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Research subject: In recent years, several studies have been performed for improving the adhesion properties of polyurethane and acrylic pressure-sensitive adhesives (PSAs). Generally, polyurethane PSAs are of higher shear strength, while acrylic PSAs have higher tack. This research is a feasibility study of exploiting the properties of both of these adhesives through a simple blending method, and the adhesion properties were evaluated.
Research approach: First, acrylic copolymer (Ac) consisting of 82 vol. % butyl acrylate and 18 vol. % methyl methacrylate was solution polymerized. On the other hand, a thermoplastic polyurethane (TPU) containing 17.5 wt. % hard segment was prepared by bulk polymerization. Blending of these two polymers was performed by solution mixing. Solutions of the pure polymers and their blends at different contents were cast on polyethylene terephthalate backing and dried at room temperature. Fourier transform infrared spectroscopy, gel permeation chromatography, and differential scanning calorimetry were used to identify TPU and Ac. Loop tack, static shear strength, dynamic mechanical behavior, contact angle of sessile drop, morphology, and haze of the PSAs were evaluated.
Main results: Tack of the acrylic PSA was higher than TPU PSA. Tack of the blend PSAs containing 20, 40, and 60 wt. % TPU was higher than the pure components and that of the blend containing 40 wt. % TPU was maximum. This blend demonstrated the lowest water contact angle compared to the other blends and the shortest relaxation time compared to the pure polymers, which resulted in better wetting and higher tack. The shear strength of the PSAs increased with increase in the content of TPU to higher than 40 wt. % in the blends compared to the acrylic PSA; so that the pure TPU showed the highest modulus at various frequencies and hence exhibited high-shear PSA characteristics in the Chang’s viscoelastic window and the highest adhesion strength. The immiscibility of the blends was confirmed by measuring the haze and calculating the Hansen solubility parameter.

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  Effect of variety, moisture and drying temperature on mechanical properties of soybean (failure force and energy, apparent modulus of elasticity and toughness) were studied. These properties were measured through quasi-static loading experiment by material testing machine. Factorial test with Randomized Block design was used to study the effect of drying parameters including final moisture content (3 levels: 10, 12 and 14% d.b.) and temperature (at 3 levels: 50, 60 and 70 ˚C) and varieties (Hill, Pershing and Gorgan3) on mechanical properties of soybean. The results showed that both drying factors (final moisture content and temperature) had significant effect on the force and energy failure. So that by increasing final moisture content from 10% to 14%, the failure force and energy increased from 47.5 N and 10 mJ to 82 N and 56 mJ, respectively. This different behavior of soybean in relation to other grains is due to a high amount of fat in soybean structure. Also by increasing drying temperature from 50˚C to 70˚C, the seed failure force was increased. Investigation of the effects of variety and moisture factors on toughness and apparent elasticity modulus showed that variety and moisture content had significant effect on three factors. Soybean elasticity modulus was 80.95 MPa at 10% moisture content, which by increasing moisture content to 14%, it decreased to 25.56 MPa. 

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Due to the lack of General Practitioners (GP) in the past two decades in Iran, increasing the number of General Practitioners has been on the strategic agenda for health sector. However, this was an appropriate action for the time but, these augments unfortunately continued without scientific considerations, while these were based on the needs of society in that time. This led to some problems for all sectors in the health system. Unemployment, misemployment, underemployment were the results of these policies. Government suffered from heavy cost of educating General Practitioners. the system faced with inequality in their performance as well. Because of the importance of the subject, this research is done for avoiding such problems. It uses mathematical and economic models and techniques to estimate the number of GP from 2006 to 2011, which is believed to be essential for the health system. In this research, Cob-Douglas production function and partial adjustment model have been used for estimating GP labor demand function, then using growth rates of variables and growth mean of the period for each variable, the needed number of GP has been estimated. The future need of GP for years of 2006, 2007, 2008, 2009, 2010, 2011 is respectively, 3864, 4507, 5282, 6224, 7384, and 9011. The elasticity is also calculated for the variables: (RInv), (RVA), (L). Point elasticities for the above variables are respectively 0.035, 0.041, and 0.01.

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Mayonnaise as an oil in water emulsion with pH<4.1 is one of the oldest man-made emulsions that one of the most widely used sauces in Iran and in the world. Nowadays, gums are widely used to increase stability and also changing the rheological properties of mayonnaise. Gum tragacanth as a plant exudation is an Iranian native gum that it indicates a high viscosity in acidic conditions. Though, it is proved that the gum obtained from different species of Astragalus have an absolutely different physico-chemical properties. So far no comprehensive research has ever been done on the effect of different species of gum tragacanth on the rheological properties of mayonnaise sauce. In this research it was attempted  to study  the effect of gum tragacanth obtained from  two  different  species  of  Astragalus  gossypinus or  Ag and  Astragalus  rahensis  or Ar  on  the flow  and  oscillatory  rheological  properties of mayonnaise  and was determined  the effect  of gum  concentration and temperature on the mentioned  properties. Finally, it was compared with the commercial sauce prepared by using imported gums. The mixture was stirred for 11 min by a rotary mixer at 1000 Rpm. pH and stability tests were done. A comparison of microstructure of the mayonnaise sauce produced with different concentrations of two species of Gum tragacanth was conducted with a light microscopy equipped by a camera. Steady flow and viscoelastic properties were determined by using a controlled shear rate Rhometer. It was shown that all treatments (type of gum and its concentration) had significant on oscillatory rheological properties. After determining the Herschel Bulklley model to describe experimental data's steady rheological tests. It was shown that the mentioned rheological factors had a significant on some of these parameters and apparent viscosity of mayonnaise sauce. A comparison of prepared mayonnaise sauce with two species of Gum tragacanth in different conditions with commercial mayonnaise sauce showed that all factors in every specific level just can make close some characteristic of produced mayonnaise to commercial sample. So the study about the effect of using mixture of different species of Gum Tragacanth with each other or with the other gums on quality of mayonnaise sauce is suggested.

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In this study, some physical properties of Jahromi lime fruits were investigated. Physical properties such as mass, main diameters, volume, density, sphericity and geometric mean diameter were measured. Material testing machine was used to measure mechanical strength by using two plates compression test. The experiments were carried out at three mass levels (m>23 g, 18 g < m <23 g, m< 18 g), three loading speeds (100, 200 and 300 mm/min) and two loading directions [vertical (in maximum diameter direction) and horizontal (in medium diameter direction)]. Strength properties such as failure force and energy, toughness and elasticity module were determined. Result of physical properties of limes showed that the averages of mass, volume, density, sphericity and geometric mean diameter were 21.48 ± 5.98 g, 21.24 ± 6.00 cm³, 1.012 ± 0.008 g/cm³, 0.90 ± 0.04 and 34.07 ± 3.27 cm, respectively. Also, results showed that loading direction, loading speed and size factors had significant effect on elasticity module (p< 0.01). Interaction effect of loading speed and the size had significant effect on the failure energy (p< 0.01) and toughness (p< 0.05). But none of them have significant effect on the failure force. Moreover, the result showed that the loading speeds have indirect relation with failure energy and direct relation with toughness and elasticity module. Therefore, size had no effect on failure energy and toughness but size and elasticity module had indirect relation. 

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In this paper linear aeroelastic analysis of a swept wing with two degrees of freedom in an incompressible flow is investigated in time - domain. The equations of the motion of an elastic wing are derived from Lagrange’s equations in time - domain. The wing is modeled as a cantilever beam rigidly connected to the root. Considering assumed modes of cantilever beam, aerodynamic forces and moments acting on the wing are derived using strip - theory in an unsteady incompressible potential fluid flow. The governing aeroelastic equations of the system have been introduced in dimensionless form. These equations are solved via a numerical method. Comparisons between obtained results and both available experimental data and the results of some cited references indicate a close agreement.

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To determine some mechanical properties of garlic bulb and its cloves, some mechanical tests was performed on a variety of Talesh local garlic at three levels of storage period with 70-day intervals. Mechanical tests are performed on three levels of loading speed and three levels of storage period. Compressive tests were performed on bulb, cloves, and on cylindrical samples taken from the tissue of garlic cloves. According to analysis of variance based on factorial experiment in randomized complete block design, the value of module of elasticity, maximum force required to rupture and toughness of cloves were measured respectively 2.762MPa to 7.091MPa, 105.043N to 167.27N and 62.358mJ/mm³ to 101.44mJ/mm³ and also the value of young module of elasticity, the maximum force required to rupture and toughness of cylindrical samples taken from tissue of garlic cloves were measured  3.368MPa to 6.981MPa, 12.606N to 25.762N and 0.173mJ/mm³ to 0.33mJ/mm³ respectively. The ranges of value of force required to loosen the bulb, while loading along the height and width direction, were measured 127.023N to 228.001N and 45.52N to 106.97N respectively.  

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Mastitis is one of the most common diseases that can affect composition of milk and hence the products derived from it. In this study oscillatory rheological tests were carried out to determine the effect of somatic cell counts(SCC) on viscoelastic properties of strained yoghurt .Results of strain sweep tests showed that by increasing SCC in samples, structural strength, yield stress, flow point and dependence of elastic modulus (G¢) to strain outside of linear viscoelastic range (LVE) were decreased. Frequency sweep test results revealed that for all samples elastic behaviour dominates the viscous one over the whole range of frequency but by increasing SCC, G* decreased and G¢ became more frequency dependent which means a weaker and also less gel structure, for samples with higher SCC. It was indicated that somatic cell count of milk is a critical factor which affects the quality and yield of strained yoghurt

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- In this paper, an analytical formulation of FGM axisymmetric thick-walled cylinders, based on the plane elasticity theory is presented. The stress and displacements in thick cylindrical shell are calculated using the real, double and complex roots of characteristic equation. Solutions are obtained under generalized plane stress, plane strain and closed-ends cylinder assumptions. It is assumed that the material is isotropic and heterogeneous with constant Poissn's ratio and radially varying elastic modulu. The results have been compared with findings of the researcher (2001) [hoop stress is incorrect], and we have present corrected version as well as supplementary findings. Keywords: Thick-Walled Cylinder, FGM, Plane Elasticity

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Abstract- In this paper, an analytical formulation of FGM axisymmetric thick-walled cylinders, based on the first shear deformation theory (FSDT) is presented. The displacements and maximum stress in thick cylindrical shells are calculated. Solutions are obtained under generalized plane strain assumptions. It is assumed that the material is isotropic and heterogeneous with constant Poissn's ratio and radially varying elastic modulu. The results have been compared with findings of the plane elasticity theory (PET).

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Carbon Nanotube (CNT) dimensions and interphase region are the important parameters that affect on the mechanical behavior of CNT/Polymer composites. In this study, a new analytical model is established to predict the modulus of these structures. Considering the influence of CNT dimensions (diameter and length) an interphase region, the elastic modulus of nanocomposite is determined. In this new model, a nanotube with hollow cylindrical structure is modeled as a transversely isotropic solid nano-fiber. Moreover, interphase region and its van-der Waals interaction is simulated as an isotropic hollow cylindrical solid that its mechanical properties is derived using the continuum mechanics. To predict the modulus of nano-composites, a representative volume element (RVE) containing a transversely isotropic solid nano-fiber, isotropic solid interphase region and the matrix is employed using Halpin-Tsai model. Finally, the results of the proposed analytical model are compared with various available experimental results. The proposed model is simple and the results obtained by the model are in good agreement with available experimental results.

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Armington elasticity measures the degree of responsiveness of relative demand of an imported good to its domestically produced one, to relative home produced-imported price ratio of that good. In fact, it shows the competitiveness (or its substitutability) of domestically produced goods with respect to the imported ones. These elasticities were estimated for 23 selected goods (because of data deficiencies) at 2, 3 and 4 digits of ISIC classification and found them (for 19 goods) positive and statistically significant.

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The combined effects of two major contributing factors, i.e. inertial soil-structure interaction (SSI) and near-fault ground motions, on structural responses were studied. Considering nearfault characteristics, soil-structure systems are subjected to both actual near-fault ground motion records and their dominant kinematic characteristics, i.e. forward rupture-directivity pulses, coherently travelling waves seen as a large amplitude and short duration pulse-type motion at the beginning of each fault-normal component of the record. As a result of the suitability of forward rupture-directivity pulses for quantifying the salient response features of structures, a mathematical model, proposed by Makris, was used to represent the forward rupture-directivity pulse-type motions. Using a comprehensive parametric study, the structure, a bilinear single degree of freedom (SDOF) system, the soil beneath the structure and a homogeneous elastic half-space were combined based on a discrete model to constitute the overall soil-structure model. The results have been presented in the form of elastic strength demand graphs for a wide range of non-dimensional key parameters, which describe the SSI effects. Both the soil-structure systems and the corresponding fixed-base structures were considered and compared. Using numerical time-stepping analyses, it was found that the response of soil-structure systems subjected to actual near-fault records is similar to those subjected to forward rupture-directivity pulses. Consequently, the forward rupture-directivity pulses can be used to predict the salient response features of soil-structure systems in seismically active regions. They can also be a realistic representation of near-fault ground motions for predicting the response of long-period structures. It was further observed that quite interestingly, the response of soil-structure systems subjected to actual near-fault records, has two maximum regions. However, it was recognized that further study would be required to clarify these regions. The results also indicated that considering SSI is critical for a variety of structures. Accordingly, underestimated near-fault responses could be obtained when the SSI effects are ignored.

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Vibration generated by vehicles during road transport has an important effect on the agricultural products damage process, particularly vegetable and fruit. Modulus of elasticity is one of the most important mechanical properties of fruits and its variation can be described as one of the damage criteria during transportation. This research was conducted to evaluate the effects of vibration parameters (frequency, acceleration and duration) and fruit position in the bin, on watermelon damage. At first, vibration frequency and acceleration were measured on the different points of a truck-bed in order to obtain the range of vibration frequency and acceleration distribution during transportation. Second, a laboratory vibrator was used to obtain some factors influencing damage during watermelons transportation. The damage was described as a difference in the modulus of elasticity of the watermelon (flesh and hull) before and after the test. According to the results measured on the truck-bed, the vibration frequency mean values were 7.50 Hz and 13.0 Hz for 5-10 Hz and 10-15 Hz frequency intervals, respectively. Furthermore, vibration acceleration mean values were 0.30 g and 0.70 g for 0.25-0.50 g and 0.50-0.75 g intervals, respectively. Vibration frequency and acceleration mean values were used for vibration simulation. Vibration durations were 30 and 60 minutes and damage was measured for watermelons at the top, middle and bottom positions in the bin. Laboratory studies indicated that, vibration frequency, vibration acceleration, vibration duration, and fruit position, which were taken into consideration as controlled variable parameters, significantly affected the damage (P< 0.01). Damage to the watermelon flesh was higher than watermelon hull. Vibration with a frequency of 7.5 Hz, acceleration of 0.70 g, and duration of 60 minutes caused higher damage levels. Fruits located at the top of the bin showed more damage than those in middle and bottom positions (P< 0.05).

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Vibration generated by vehicles during road transport has an important effect on the agricultural products damage process, particularly vegetable and fruit. Modulus of elasticity is one of the most important mechanical properties of fruits and its variation can be described as one of the damage criteria during transportation. This research was conducted to evaluate the effects of vibration parameters (frequency, acceleration and duration) and fruit position in the bin, on watermelon damage. At first, vibration frequency and acceleration were measured on the different points of a truck-bed in order to obtain the range of vibration frequency and acceleration distribution during transportation. Second, a laboratory vibrator was used to obtain some factors influencing damage during watermelons transportation. The damage was described as a difference in the modulus of elasticity of the watermelon (flesh and hull) before and after the test. According to the results measured on the truck-bed, the vibration frequency mean values were 7.50 Hz and 13.0 Hz for 5-10 Hz and 10-15 Hz frequency intervals, respectively. Furthermore, vibration acceleration mean values were 0.30 g and 0.70 g for 0.25-0.50 g and 0.50-0.75 g intervals, respectively. Vibration frequency and acceleration mean values were used for vibration simulation. Vibration durations were 30 and 60 minutes and damage was measured for watermelons at the top, middle and bottom positions in the bin. Laboratory studies indicated that, vibration frequency, vibration acceleration, vibration duration, and fruit position, which were taken into consideration as controlled variable parameters, significantly affected the damage (P< 0.01). Damage to the watermelon flesh was higher than watermelon hull. Vibration with a frequency of 7.5 Hz, acceleration of 0.70 g, and duration of 60 minutes caused higher damage levels. Fruits located at the top of the bin showed more damage than those in middle and bottom positions (P< 0.05).

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This research is dedicated to the estimation of the effective elastic modulus of polymer concrete by a new micromechanical model. The capability of the equivalent inclusion methods have been proved by numerous researches. The Mori-Tanaka (M-T) model is the most used homogenization scheme for two-phase composite materials. The M-T model provides good estimates of the stiffness tensor for two-phase composites with low to moderate volume fraction of inclusions. However, when the volume fraction of reinforcing phase is high, M-T model is unable to predict the stiffness tensor accurately. The major disadvantage of M-T model is that when volume fraction is high, in the associated isolated inclusion medium (AIIM), the properties of the reinforcing phase does not affect the matrix properties. The idea of the proposed model is that in high volume fraction of the associated isolated inclusion medium, the matrix phase must be affected by the reinforcing phase properties. In order to evaluate this model, twelve components with two different compositions were manufactured and tested. Also, the results from other researches were used to evaluate this model. The validation of the proposed model with the experimental data and results by other researchers shows the remarkable predictive capability of this model.

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In this paper, a linear model for vibration of electrostatically actuated annular microplate with In this paper, a linear model for symmetrical vibrations of electrostatically actuated annular microplate with thermoelastic damping is considered for calculating the quality factor of this damping. The Kirchhoff–Love plate theory is used to model the microplate which is coupled with thermal conduction equation one dimensionally. For calculating the Q-factors in each mode, two methods are compared with respect to linearization of frequency equation. Also the dependency of thermoelastic damping to electrostatic load and geometry of annular microplate is investigated with clamped-clamped and clamped-free boundaries. A silicon annular microplate is considered as an example. The results show that, there are a critical radius and thickness which make the thermoelastic damping to be maximal. Also the results show that the effect of electrostatic load on thermoelastic damping depends on the type of boundary conditions. The effect of electrostatic load on thermoelastic damping for clamped-free boundaries is more than for clamped-clamped boundaries.