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A project was established to develop a procedure for the selection, design, installation, test and evaluation of mass-flow rate measurement systems for root crop harvesting and to assess the consistency and precision of the weighing systems incorporated into crop feed arrangements in both laboratory and field studies. Studies were conducted to evaluate conveyor belt weighing systems using an experimental apparatus and a commercial potato harvester. Two weighing systems were evaluated: (a) cantilever transducers fitted to the conveyor belt mechanism and (b) a load cell system supporting the total weight of the conveyor and crop. The results of laboratory studies with sugar beet/potatoes showed that the standard cantilever transducers gave the smallest percentage of standard deviation from the mean experimental error ranging from 1.43 kg (connected to one idler roller) to 2.61 kg(connected to three idler rollers) with an appropriate value equal to 0.54 kg (connected to two idler rollers). The load cell supporting system also gave the smallest percentage of standard deviation from the mean experimental error ranging from 1.56 kg (continuous side feeding) to 2.25 kg (side feeding from right side) with an appropriate value equal to 0.84 kg (steady state side feeding). Experiments were conducted in the laboratory and field to assess the effects of belt inclination and extraneous vibration, transferred from the tractor to the harvester, on the measurements of crop mass. The results of field studies with potatoes using the cantilever transducers showed that the most precise system performance was obtained when using the 125 mm idler wheels with standard deviation of the mean experimental error of the sample yield equal to 0.99 kg. The results of barn studies with potatoes using the load cell supporting system showed that there was a good linear relationship between the measured and weighed mass of the potato samples with standard deviation of the mean experimental error equal to 0.34 kg.

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There is not enough information about postharvest physiological behavior and optimum storage temperature of cultivated persimmons in Karaj region of Iran. In this study, persimmon fruit, cv. Karaj, was harvested at mature stage and was treated with hot waters at 45 and 50°C for 20, 30 and 45 min. Besides, one lot of fruit was bathed at 25°C for 30 min as control treatment. The physiological behaviors of treated fruits were monitored during 4 months storage at 0, 2 and 5°C. Results showed that severity of symptoms, such as; skin browning index, fruit softening, fungal disease incidence and loss of color indices (L*, a*, b*), were higher in storage at 2 and 5°C than storage at 0°C. Therefore, ʻKarajʼ persimmon was tolerant to 0°C for storing purpose. On the other hand, hot water treatments at 45°C for 30 and 45 min and 50°C for 20 min maintained fruit firmness and color properties, and controlled disease incidence better than that of control and hot water treatment at 45°C for 20 min. However, hot water treatment at 50°C for 30 and 45 min, in spite of maintaining suitable colour properties, contrary with other effective treatments caused to fruit skin browning and had notociable fungal disease. Therefore, hot water treatments at 45°C for 30 and 45 min and 50°C for 20 min are the recommendable treatments for increasing postharvest life of Karaj persimmon.  

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The main postharvest problems of persimmon in Iran are severe softening and disease incidence on the fruits during storage. Therefore, delay in softening and/or control of diseases result in the storage life extension of persimmon fruit. The strategy of induced disease resistance in plants by biotic and abiotic treatments is an attractive method for controlling diseases. Salicylic acid (SA) is a well known natural inducer of disease resistance in plants. In this study persimmon fruits cv. Karaj were treated at harvest with SA at 0 (as control), 1 and 2 mM and the quality parameters of the fruit were measured during 3 months of storage at monthly intervals. The most noticeable effect of postharvest SA application on stored persimmon fruit was the reduction of disease incidence at 2 mM concentration, while 1 mM SA failed to control diseases. Results showed that SA did not affect TSS, titratable acidity, soluble tannin content, and fruit firmness. Also, SA could not suppress ethylene production compared to the control. SA treatment at 2 mM concentration reduced postharvest disease incidence of persimmon fruit by inducible defense mechanism, being suitable for increasing postharvest life of the fruit.

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In this paper, plastic deformation of the clamped mild steel and aluminum circular plates subjected to different hydrodynamic impact loading conditions are investigated. Extensive experimental tests were carried out by using a drop hammer. The experimental results presented in terms of central deflection of the plates, deflection profiles, and strain distributions. The effect of different parameters such as material properties, plate thickness, stand off distance of hammer or the transfer energy were also investigated on behavior of deformation of plate. Analytical modeling was carried out using energy approach and introducing the deflection profile function based on observes result of experimental. In this model effect of strain rate, hoop strain, radius strain and also effects of bending strain energy and membrane strain energy have been inserted. Calculations of the cases indicate that the proposed analytical models are based on reasonable assumptions. So, this method can be used for study of plastic deformation of plates under dynamic loading. The agreement between analytical and experimental results indicates that new analytical approach presented in this work maybe successfully employed for prediction of central deflection in different hydrodynamic impact loading conditions.

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The main aim of this paper is to study the inelastic deformation of fully clamped rectangular plates under hydrodynamic loading by low rate with drop-hammer, both experimentally and analytically. In the analytic section, some models are presented for predicting the mid-point deflection by two methods consisting the plastic hinge and energy method. in the plastic hinge method, it is assumed that the used plate in the experimental analysis consists a central hinge and four decentralized hinge inside and also four hinges for fully clamed supported conditions; but in the energy method, the proposed model assumes the deformation in three directions and membrane and bending strain, besides the deformation profile and also the strain rate is assumed. To do this, in experimental section, some experiments were conducted on rectangular plates with different thickness, materials and different levels of energy in order to validate the obtained results from analytic results and also surveying the mechanical behavior of materials according to impacts. By comparing analytic and experimental results, it is obvious that results have satisfying accuracy, therefore using the presented analytic models is desired for predicting the mid-point deflection of rectangular plates under the hydrodynamic loading.

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The purpose of this paper is to investigate those products which are produced by powder compaction procedure under the low rate impact loading by a drop hammer, both theretically and numerically. Experimental section includes checking the efficiency of density, bending strength and elasticity modulus of the product from grain size and different levels of energy. Two kinds of pure aluminum powder in three different size and also their combination with ceramic are used to obtain this. In the numerical section, dimension analysis method is applied in which non-dimensional models for density, bending strength, and elasticity modulus are presented in form of mathematical functions by means of experimental characteristics and data which are categorized to input and output. The purpose of determination of this model is to reach a reliable and satisfactory prediction for final properties of products subjected to impact loading condition. It is worth to note that singular value decomposition approach is used for calculation of linear coefficients vector which has been obtained by non-dimensional parameters.A comparison between these results and experimental data is done by mathematical functions in order to validate the results. The investigation of training and prediction data errors which has been based on root of mean of squares of error and coefficient of determination shows that the obtained results through mathematical functions have acceptable accuracy; hence utilization of the presented mathematical models for predicting the final properties of product subjected to impact loading is desirable.

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The aim of this paper is to investigate the green density, the percentage of porosity and the density distribution of materials which have been produced by powder compaction procedure under low rate impact loading by using drop hammer both experimentally and analytically. Effect of grain size and different level of energy on density is carried out in the experimental section. In this regard, the effect of different level of energy are investigated by changing mass and height of hammer. The analytical section presents a relation for green density considering a small element of compacting piece and using equilibrium equation, continuity equation and Levy-Mises equation. Using the statistical analysis leads to investigation of the effect of grain size and friction coefficient simultaneously as two impressive factors on analytical green density. In the next step, the percentage of porosity and density distribution was calculated analytically and compared with experimental values. The satisfactory accordance between Experimental results and analytical ones validates the presented analytical results. Also by applying two constant quantities, shape factor and work hardening in analytical relations, the effect of these factors on percentage of porosity and density distribution of products have been investigated.

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The purpose of this research is to develop relationships to predict the results of measuring the electrical resistivity of the standard test method ASTM C1760 with assistance of other methods’ results. Comparative Methods in this paper are Impedance spectroscopy method , one electrode method and four electrode method. Impedance spectroscopy method is the most common in laboratory studies , ASTM C1760 method (Standard Test Method for Bulk Electrical Conductivity of Hardened Concrete) only has a standard rule and use in laboratory , one electrode method is a new technique in field and it’s application is in the reinforcement structures , and four electrode measurements are more common in field. In laboratory methods, bulk electrical resisitivity measured but in field , usually surface electrical resisitivty evaluated , that is why several source of errors affecting on the results of this test methods. To reach the aim of this research , 49 mix designs with a vast domination of electrical resistivity from about 40 (Ω-m) to 290 (Ω-m) was intended and for each of mix designs , 4 cylindrical and one reinforced slab specimen were made. reinforced slab specimen for one electrode measurement and cylindrical specimens for the other test method measurments were considered. Moreover , the electrical resistance of the aforementioned methods was measured at 28 days age. The results showed that there is a negligible difference between the results of impedance spectroscopy and ASTM C1760 methods; however , the electrical resistivity measured by ASTM C1760 method was slightly higher than the results of impedance spectroscopy method in the concrete. As a result , we can use the results of the impedance spectroscopy method instead of standard test method results in the lack of facilities with accepting about 5% of error. In the four electrode method , a number of factors including the imbalance among the distances between electrodes and structure dimensions can result systematic errors. That is why the measurements’ results with the method is approximately 140% larger than the standard test method results. Due to the lack of a comprehensive relationship for calculating the cell constant in the one electrode method , the value of this constant was obtained by comparing the results of the standard test method. After that , the electrical resistivity values were calculated. Electrical resistivity measurement results which was obtained by this method had also little difference with the standard test method results. Finally 3 relationships separately developed for predicting the result of standard test method from results of the each other test methods. Since the features and conditions of measuring by the standard test method are not available in the entire projects , the current results are capable to predict the standard method’s results with assistance of other methods’ results.

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This work aims to prediction of laminar/turbulent transition which plays an important role on aerodynamics of wing section. In this respect the flow around the NACA2415 airfoil simulated in a Computational Fluid Dynamics (CFD) solver in different regimes with and without propeller flowfield. For predicting the transition onset, two approaches were used: The first is based on time history of the skin-friction coefficient for determining the transition onset and the transition length on the airfoil. The second is to apply transition γ-〖Re〗_θ model for laminar/turbulent transition simulation. For investigation of transition effect, the simulation repeated by use of a classical turbulent model and both results was compared with experimental data. The comparison shows that taking into account the transition effects gives a good agreement with experiment. Relative error of calculated drag coefficients for the transition based simulation is lower than 10%, while fully turbulent simulation are 70% overestimated in some incidences. Slipstream of upstream propeller changes flow pattern and boundary layer characteristics over the wing. Indeed in presence of propeller, spanwise load distribution and laminar/turbulent transition onset were affected. In propeller flowfield, increasing of velocity normal component over wing surface causes transition delay. Movement of transition onset to trailing edge on the upper surface in propeller downwash is representative of such phenomenon. On the other hand, in upwash region, the transition onset moves upstream. With the increasing propeller rotational speed, this tendency augments and so the transition onset on the wing upper surface moves far downstream in propeller downwash.

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Various researches have been performed regarding the deterioration and behavior of fabrics made from carbon, glass and aramid in different environmental conditions. Carbon fibers reinforced polymer (FRP) are very corrosion resistant. The CFRP laminates are extremely useful in very corrosive atmospheres, such as marine and aggressive chemical atmospheres. They have been advanced over the years because of their high strength, light weight, long-term durability and high resistance to deterioration. The very thin (0.2 - 0.4 mm) laminates are very easy to apply and can be applied in cross directions without any difficulty. Environmental conditions impact on the bond strength of FRP-to-concrete has sparsely been investigated. The sources of CFRP bond deterioration can originate from alkaline attack and thermal expansion. Alkaline attack occurs at the interface of the concrete and a CFRP laminates with the resulting damage to the matrix of the CFRP laminates. Also, alkali aggregate reaction can lead to the destruction of concrete elements. However, studies in this field are not enough and for externally bonded FRP materials, no such long term test results are available yet. Severe corrosion damage can often be prevented by a correct treatment of the structure against chemical influences or aggressive environmental effects. Methods such as the externally bonded reinforcement (EBR), despite of their advantages, have a problem known as the premature debonding of FRP from concrete substrate. In this method the surface of concrete is sanded and cleaned. After the preparation of the surface, the layer of epoxy is applied uniformly on the surface of concrete. Then, FRP is installed on the surface and saturated with epoxy. In other hand, a new strengthen method is the externally bonded reinforced on grooves (EBROG) method that consists of grooves on the surface of concrete. In this method, grooves with a proper length, width and depth are catted on the concrete surface; then the concrete surface and the grooves are cleaned with an air pressure. Later, grooves are filled with an appropriate epoxy. At the end, FRP sheets are installed with a proper epoxy on the concrete surface. In this paper, the effect of environmental conditions, including three alkaline environments with temperatures of 〖 23〗^° C, 〖40〗^° C and 〖60〗^° C, was investigated on the bond strength of FRP-to-concrete. The specimens were strengthened with two methods: EBR and EBROG. Samples were kept in environmental conditions for 3000 hours. Single-shear tests were conducted to evaluate the bond behavior of FRP-to-concrete. Experimental results showed that the specimens strengthened by the EBROG method - in the alkali environment with different conditions - experienced up to 50 % higher than ultimate bond loads compared with the specimens which were strengthened by the EBR method. In the EBR method, the bond failure mode changed from concrete delamination in laboratory condition to epoxy-concrete interface separation in alkali immersion with different temperatures. On the other hand, in the EBROG method environmental conditions had not effect on the mode of failure and more than 90% of specimens experienced FRP rupture. As a whole, the alkali environment caused a sudden drop in the bond strength of FRP-to-concrete substrate.

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Analytical and experimental investigation of the RC beams shear-strengthened with NSM Method along with Case studies
 
Abstract
This paper examines the structural behavior of the reinforced concrete beams strengthened in shear experimentally and simulates using finite element analysis. Then, the effect of employing concrete with different compressive strengths and different ratios of transverse reinforcements is studied using the case analyses. In the experimental part, four reinforced concrete beams are divided into two series of with and without internal steel reinforcements and the effect of carbon-fiber-reinforced polymer (CFRP) laminates is investigated by near-surface mounted (NSM) technique as the shear strengthening method. For this purpose, rectangular beams with the dimensions 2000×300×200 mm are designed and monolithically tested in four point loading test up to failure and the load-displacement curves of the mid-span as well as their failure modes are compared with each other. All the beams were reinforced with 3 steel tension bars of 20 mm at the bottom and 2 steel compression bars of 12 mm at the top with end hooks. If stirrups are applicable, 6 mm diameter steel closed hoops spaced at designated distances, are applied. For strengthening using the NSM method, thin slots with 8 mm width and 10 mm depth are made on lateral faces of concrete cover. In order to install composite laminates, the CFRP strips after impregnating with strong epoxy resin are folded and embedded in these grooves. After curing the specimens, all the beams are subjected to a 2000 kN capacity hydraulic jack with the loading rate of 2.5 kN/Min. The ready-mix commercially concrete was delivered to the structural laboratory for casting the specimens with 28-day concrete strength of 30 MPa. The ACI code formulations were used for calculating the shear capacity of the beams before their casting and a suitable span to depth ratio was selected to inhibit deep beam failure. The experimental results indicate that using NSM technique enhances the shear capacity up to 41% and 69% in the beams with and without stirrups, respectively. Test results show that the NSM shear strengthened specimens failed by CFRP laminate rupture. Moreover, simulation of the test specimens by modeling the probability of FRP de-bonding using interface element and orthotropic behavior of laminates shows that the results of the proposed model are consistent with experimental results. In the numerical part, two case studies are carried out; in the first case analysis, three concrete compressive strengths of 20, 30 and 50 MPa are selected and in the second one, three steel stirrup spacing of 65, 130 and 190 mm are applied.  Numerical case analyses show that as the compressive strength of concrete decreases, the failure mode the probability of de-bonding increases and as the stirrup percentage increases, the axial strain of CFRP laminates decreases. Numerical case analysis clarifies that by decreasing the distance of internal shear reinforcements from 195 mm to 65 mm, the maximum axial strain of CFRP laminate decreases about 45%. Load-deflection curves in the case analysis also show that by increasing the transverse steel ratio, ultimate displacement enhances and deformability capacity improves.

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Grain design is the most important part of a solid rocket motor. The aim of this study is finocyl grain design based on predetermined objective function with respect to ballistic curves in order to satisfy various thrust performance requirements through an innovative design approach using a genetic algorithm optimization method. The classical sampling method has been used for design space-filling. The level set method has been used for simulating the evolution of the burning surface in the propellant grain. An algorithm has been developed beside the level set code that prepares the initial grain configuration using Pro/Engineer software to export generated models to level set code. The lumped method has been used to perform internal ballistic analysis. Two meta-models are used to surrogate the level set method in the optimization design loop. The first method is based on adaptive basis function construction and the second method is based on the artificial neural network. In order to validate the proposed algorithm, a grain finosyl sample has been investigated. The results show that both grain design method reduced the design time significantly and this algorithm can be used in designing of any grain configuration. In addition, data have more accuracy in grain design based on the artificial neural network, so this method is the more effective and practical method to grain burn-back training.

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