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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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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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- 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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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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In this paper, an approximate solution using layer-wise theory for the vibration analysis of rotating laminated cylindrical shells with ring and stringer stiffeners under axial load and pressure is presented. The cylindrical shells are stiffened with uniform interval and it is assumed that the stiffeners have the same material and geometric properties and cylindrical shell reinforced by outer stiffeners while stiffeners are treated as discrete elements. The equations of motion are derived by the Hamilton’s principle. In deriving the governing equations three-dimensional elasticity theory are used and the study includes the effects of the Coriolis and centrifugal accelerations and the initial hoop tension. The layer-wise theory is used to discretize the equations of motion and the related boundary conditions through the thickness of the shells. The edges of the shell are restrained by simply supported boundary conditions. The presented results are compared with those available in the literature and also with the FE results and excellent agreement is observed. Finally, the results obtained include the relationship between frequency characteristics of stiffened cylindrical shell and different geometry of stiffeners, stiffener type, rotating velocities, amplitude of pressure and amplitude of axial load.

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In this paper, analytical solutions of low velocity transverse impact of a nanoparticle on a nanobeam are presented by using the nonlocal theory to bring out the effect of the nonlocal behavior on dynamic deflection. Impact of a mass on simply supported and clamped nanobeams are investigated by using nonlocal Euler–Bernoulli beam theory. In order to obtain an analytical result for this problem, an approximate method has been developed wherein the applied impulse is replaced by a suitable boundary condition. A number of numerical examples with analytical solutions for both nonlocal and classic beam have been presented and discussed. The dynamic deflection predicted by the classical theory is always smaller than those predicted by the nonlocal theory due to the nonlocal effects. The inclusion of the nonlocal effect increases the magnitudes of dynamic deflection and decreases frequencies. Furthermore, the mass and the velocity of the nanoparticle (striker) have significant effects on the dynamic behavior of nanobeam.

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In this study the effect of thermocycling on the mechanical properties of a commercial dental nano-composite (Filtek Z350 XT, 3M ESPE, Germany) was investigated by using the nano-indentation experiment. For this purpose some disk specimens, each of the diameter 10 mm and the thickness 4 mm were prepared. Half of the specimens were stored at room temperature and the other half were thermocycled in distilled water for 1000 cycles between temperatures 5°C and 55°C. After the sample preparation, the nano-indentation test was applied on both non-themocycled and thermocycled specimens by Triboscope setup. Then the modulus of elasticity and hardness of the test samples were calculated from the Oliver-Pharr’s method using the data obtained from the nano-indentation experiments. Using the independent-samples t-test, the mechanical properties obtained from the non-thermocycled and thermocycled samples were compared. The results indicate that thermocycling process increases the modulus of elasticity and hardness of the dental nano-composite.

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In this article, analytical solutions of low velocity transverse impact on a nanobeam are presented using the nonlocal theory to bring out the effect of the nonlocal behavior on dynamic deflections. Impact of a projectile (mass) on simply supported and clamped nanobeams are investigated using nonlocal Timoshenko beam theory. In order to obtain an analytical result for this problem, an approximate method has been developed wherein the applied impulse is replaced by a suitable boundary condition and initial momentum of projectile and nanobeam. A number of numerical examples with analytical solutions for nonlocal nanobeam and classical beam (steel and aluminum) have been presented and discussed. When the value of the striker mass is increased, the frequencies are decreased and the maximum dynamic deflection at the center of the beam is increased for both of the simply supported and the clamped-clamped nanobeams. The inclusion of the nonlocal effect increases the magnitudes of dynamic deflections and decreases frequencies. Furthermore, the mass and the velocity of the nanoparticle (striker) have significant effects on the dynamic behavior of nanobeam.

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In this paper, interlaminar stresses resulting from static behavior of laminated plates, which were made from composite materials, were evaluated. To this end, out-of-plane stresses and displacements were considered as a primary variable. In addition, for the problem analysis, the boundary value problem method was expanded in order to form a first-order linear differential equations system which depended on the laminate thickness. This method could consider normal and transverse stresses and investigates a three-dimensional stress field near the free edge of the layers. In the proposed model, a laminated plate was placed on a simply supported boundary condition and under transverse loading. It was also assumed that the interlaminar transverse stresses, and displacements were continuous in layers' interfaces. The governing differential equations system was solved using Navier's approach and shooting method and, finally, the obtained results were compared with the results of other references. The results indicated good accuracy and high speed of the method used in analyzing stress field.

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This note presents a theoretical analysis and numerical simulation of hydraulic transients in pressurized pipeline system made of a local polyethylene pipe-wall located at a steel pipeline system. The continuity and momentum equations are solved by the method of characteristic (MOC) taking into account the viscoelastic effect of the pipe-wall for polyethylene pipe. The polyethylene pipe length and location at the pipeline and the discharge flow rate are changed and their influence on transient flow is investigated. By comparing this pipeline system with one that is made of polyethylene pipe totally, the possibility of using local polyethylene pipe due to its effect on the pressure wave is investigated.

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In this paper, exact closed-form solutions in explicit forms are presented to investigate small scale effects on the buckling of Lévy-type rectangular nanoplates based on the Reddy’s nonlocal third-order shear deformation plate theory. Two other edges may be restrained by different combinations of free, simply supported, or clamped boundary conditions. Hamilton’s principle is used to derive the nonlocal equations of motion and natural boundary conditions of the nanoplate. Two comparison studies with analytical and numerical techniques reported in literature are carried out to demonstrate the high accuracy of the present new formulation. Comprehensive benchmark results with considering the small scale effects on buckling load ratios and non-dimensional buckling loads of rectangular nanoplates with different combinations of boundary conditions are tabulated for various values of nonlocal parameters, aspect ratios and thickness to length ratios. Due to the inherent features of the present exact closed-form solution, the present findings will be a useful benchmark for evaluating the accuracy of other analytical and numerical methods, which will be developed by researchers in the future. Also, the present study may be useful for static and dynamic analysis of thicker nano scale plate-like structures, multi-layer graphene and graphite as composite or sandwich structures.

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In this paper, the effect of size of an atomic force microscope (AFM) with an assembled cantilever probe (ACP) on resonant frequencies and their sensitivities are investigated using the strain gradient elasticity theory. The proposed ACP comprises a horizontal microcantilever, an extension and a tip located at the free end of the extension, which make the AFM capable of scanning the sample sidewall. First, the governing differential equation of motion and boundary conditions for dynamic analysis are obtained by a combination of the basic equations of the strain gradient elasticity theory and Hamilton principle. Afterwards, the flexural resonant frequency and sensitivity of the proposed AFM microcantilever are obtained numerically. The results of the proposed method are compared with those of modified couple stress and classical beam theories. The comparison shows that the difference between the results predicted by the strain gradient elasticity theory with those obtained by couple stress and classical beam theories become significant when the horizontal cantilever thickness comes approximately close to the material length scale parameter.