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The objective of this study was to test whether the stimuli of osmotic pressure (OP), VFA or pH in the omasum would affect the passage of digesta from the rumen and feed intake in sheep. Five experements were carried out. Different solutions with specific, OP, VFA concentration and pH were infused into the omasal body. Rumen digesta volumes and outflow rates (liquid and solid) were measured by pulse dosing of liquid and solid marker into the rumen. Feed intake, solid and liquid outflow rates from the reticulo-rumen were (not always significant) reduced by increasing the (OP) of the infusate in the range of 400 to 2000 mOsmol/kg which gave calculated omasal OP up to 480 mOsmol/kg (perfect mixing with digesta was assumed). Feed intake and fractional ruminal liquid out-flow rate were significantly increased by increasing VFA concentration of infusate in the range of 50 to 250 mMol/l or calculated omasal VFA concentrations up to 150 mOsmol/kg with the suggestion of a decrease above this range. pH in the range of 5.0 to 7.0 was with-out effect. Serum OP was not affected by any infusate. There was no or only a weak re-sponse to abomasal infusion compared with omasal infusion when the same infusate was used. The study demonstrated that omasum responds to changes in the composition of di-gesta. Increasing OP reduced DMI (dry matter intake) and reduced digesta outflow from the reticulo-rumen. Increasing VFA concentration increased DMI and liquid outflow, high VFA concentration decreased DMI and liquid outflow rate. It can be concluded that omasum has a role in the control of digesta outflow from the rumen.

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Research subject: In recent years, due to limited water resources and the extraordinary increase in nitrates in the environment, efforts to remove and control in order to benefit from the natural adsorbents have been made. Although according to the negatively charged surface of bentonite particles, absorbent needs improvement.
Research approach: In the current study, the adsorption of nitrate columns by the modified calcium montmorillonite adsorbent was investigated. Furthermore, In order to change the surface load and increase the adsorption efficiency, three-step acid leaching, oxidation layering, and loading of the cationic surfactant hexadecyltrimethylammonium bromide on the adsorbent were performed. Molecular interaction and crystallography of pure montmorillonite and synthetic nano-adsorbent (ACZ) were characterized by Fourier transform infrared spectroscopy and X-ray analysis. Moreover, the morphology of ACZ nano adsorbents was evaluated using Transmission electron microscopy and scanning electron microscopy.
Main results: Nanoparticle compaction and less access to pores and cavities in the fixed bed column reduced the adsorbent capacity inside the column compared to the discontinuous system.
The results showed that an increase in inlet concentration from 80 to 150 mg/L increased the adsorption capacity from 67.39 to 88.25 mg/g. Reducing the inlet flow rate increased the penetration time, interaction, and greater access to the binding sites for nitrate ions and finally improved the column performance and increased the inlet flow rate reduced the adsorption capacity and breakthrough time. Therefore, the adsorption of nitrate ions by the stage of internal mass transfer is controlled and depends on the duration of interaction and the possibility of penetration into the active sites. With increasing the bed height from 4.2 to 9 cm, there was a significant increase in adsorption capacity from 60.608 to 77.167 mg/g. The effect of detergents and recovery showed an absorption column; After 3 leaching steps, acid leaching played an important role in increasing column recovery. Experimental data with correlation coefficients of R²>0.95 corresponded to Thomas and Yoon-Nelson kinetic models.
In this study, the ACZ nano adsorbent column for rapid removal of nitrate ions from aqueous solutions was introduced and for use in reusable systems was proposed.
 

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In this paper, mass flow rate and location of leakage in natural gas pipeline has been estimated simultaneously using inverse analysis. For doing so, at first natural gas transient flow in pipeline has been simulated numerically; this simulation is named direct problem. In the direct problem, it is assumed that the mass flow rate and location of leakage is definite and the governing equations are inhomogeneous well-known Euler equations. In these equations, the leakage effect has been considered as a source term. Steger–Warming flux splitting method has been used for numerical analysis of these equations. Then the location and mass flow rate of gas leakage of pipeline have been estimated simultaneously using Levenberg-Marquardt method for parameter estimation. This method is an iterative algorithm and based on minimizing the sum of the squares of the errors which are difference between pressures computed by the direct problem and pressures measured by pressure gauges. The results of the direct problem have good agreement with Mac–Cormack method and characteristics method of specified time intervals. The results of the inverse analysis demonstrate that Levenberg-Marquardt algorithm is stable and efficient enough to estimate simultaneously the mass flow rate and location of leakage in natural gas pipeline.

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Knowledge of resistance to airflow through agricultural products is an important consideration in the design of drying, cooling, or aeration systems and proper fan selection for these systems. Resistance to airflow of bulk chickpea seeds was studied at moisture contents in the range of 9.21 to 21.36 % (wet basis) for airflow rate range from 0.02 to 0.50 m3 s-1 m-2, using an experimental test column. The effects of airflow rate, bed depth (0.25 to 1 m) fill method (loose and dense) and moisture content on airflow resistance of chickpea samples were investigated. Results indicated that the airflow resistance of chickpea seeds increased with increase in airflow rate, bed depth, and decreased moisture content. One percent increase in moisture content decreased the pressure drop about 2.94%. The dense fill method resulted in an increase in resistance to airflow by about 33.17% more than that of the loose fill. Three models (Shedd’s, Hukill and Ives’s, and Ergun’s models) were fitted to the experimental data at each moisture level and were examined with two parameters. Shedd’s model that gave a higher value for the coefficient of determination and a lower value for the mean relative percentage error of pressure drop predication was found to be the best model to describe airflow resistance of chickpea seeds.

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To investigate the root anatomy and hydraulic conductivity of wheat cultivars, including Shiraz, Bahar, Pishtaz, Sistan, and Yavaros, a series of controlled environment (growth chamber) experiments were hydroponically conducted at University College of Dublin (UCD), Ireland in 2010. Bahar, Pishtaz and Sistan cultivars were employed as tolerant to drought and Shiraz and Yavaros as sensitive. Twelve plants from each wheat cultivar in three replications were compared in a completely randomized design. Seminal roots had four to five cortical cell layers, and typically one large central metaxylem and 5±1 (in Bahar) to 7±1 (in Yavaros) smaller and circularly arranged peripheral metaxylem vessels. Stellar cells were less lignified in adventitious roots, as compared with seminal roots, and mature xylem vessels of seminal roots of Shiraz and Yavaros cultivars had more lignified walls compared to the other cultivars of the 18 day old plants. Lateral roots of Shiraz cultivar showed the most lignified walls compared to the other cultivars. The highest root hydraulic conductivity in seminal roots was observed in Bahar with the lowest surface area and lignified cell walls. Type of cultivar had also a noticeable effect on flow rate of seminal roots and varied from 2.81 in Shiraz to 3.76×10^-10 m s^-1 in Bahar cultivar. With respect to flow rate and osmotic driving force of seminal and adventitious roots, Bahar and Sistan cultivars had the highest hydraulic conductivity. It was concluded that at the early growth stage of wheat cultivars (3^rd leaf stage), root anatomical structures of Bahar and Sistan were more efficient in water uptake and this might be attributed to the less lignified cell wall of the peripheral and central metaxylem zones of the roots in these cultivars.

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The existing studies of threshing process of combine harvesters adopt the assumption of constant mass, which is contradictory to the phenomenon of separation of grains and short stalks in actual threshing process. Therefore, the characteristics of threshing and separation are not accurately described. Aiming at this problem, this study established the tangential-longitudinal threshing and separation test-bed with tangential-flow device, auxiliary feed beater, and longitudinal-flow device of tangential-longitudinal-flow combine harvester and conducted experiments and analysis of rice threshing with feed rates of 5, 6, and 7 kg s^-1. The results showed that the changes in rates of material flow along the arc-length of concave in tangential-flow device and longitudinal-flow device were equal to the changes in rates of material density with time. In the process of variable-mass and constant-mass rice threshing, when the feeding rates were 5, 6, and 7 kg s^-1 in the test-bed, the flow rates from the tangential-flow device were 4.07, 5.01, and 5.95 kg s^-1, respectively. The average power consumption of the tangential-flow drum in variable mass threshing process was higher than that in the constant mass threshing process by 2.16, 2.73, and 3.09kW, respectively. The flow rate at the outlet of the longitudinal-flow device was 3.34, 4.04, and 4.72 kg s^-1, respectively. The average power consumption rate of the longitudinal-flow drum in variable mass threshing process was lower than that in the constant mass threshing process by 7.32, 10.44, and 12.17kW, respectively. The results of material flow rate and power consumption would offer the basis for the design of longitudinal-tangential flow threshing and separation device.

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In this research the effect of the screw angle and the depth of the channel were examined on the flow rate of an incompressible Newtonian isothermal and a non-Newtonian fluid flow in a single screw extruder. In the presented study the pressure drop has not been considered and only drag force was considered. For this purpose, the channel of extruder was assumed a cubic and spiral channel. Accordingly the Newtonian flow was simulated by Fluent foftware package and the results were compared with analytical solution in several angles. Then one step from the shallow spiral channel was examined and the results were compared with analytical solution in different angles and also at low Reynolds numbers. Hence, the obtained results reveal the range of validity for the analytical solution at different Reynolds numbers. As the results show, at low Reynolds numbers, up to 10, and the ratio of channel depth to diameter, less than 0.2, numerical and analytical results are the same for Newtonian fluids. Identically in this range the analytical solution can be used for screw design, calculation of the maximum flow rate, the evaluation of the optimum angle, etc. The results of the study of non-Newtonian fluid showed that the flow rate at low screw angles for non­-Newtonian fluids were higher than the Newtonian cases and at high angles, were smaller.

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Electrospray is a branch of the scientific area of electrohydrodynamics which is based on electrical charging of liquids. The electrospray governing equations are a combination of hydrodynamic and electrostatic equations to which the addition of liquid breakup process escalates their complexity. This research work aims at developing a numerical solver to simulate the electrospray process in an emitter-disc configuration using Heptane as a working liquid under various electrical potentials. The simulation results in comparison with CFD and experimental data show good agreements both quantitatively and qualitatively. The results clearly have captured the formation of liquid flow profiles at the emitter exit demonstrating various electrospray modes. These modes initiate a microdripping mode at the lowest voltage, i.e. 3.5kV, prompting consecutively to spindle and pulsating cone-jet modes and ending in a stable cone-jet mode at the highest charging voltage, i.e. 6.5kV. In addition, it is also observed that the liquid cone and the vortex shaped within it would shrink as an increase in the electric potential is imposed. Although the increase in electric potential results in rise of the maximum magnitudes of electric field and velocity, the electric charge accumulation at all electric potential values occurs on the outer surface of the liquid flow implying its electrical conductivity.

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In this paper, the effect of extrusion die profile on the dimensional tolerance of a cross section of a part in a forward extrusion process was studied. In these experimental and numerical investigations, some parameters such as extrusion speed, metal flow, extrusion temperature and extrusion force were considered as process variables. The specimen was aluminium alloy 2014 with a variable wall thickness. The variable wall thickness causes the metal flow rate to be changed along the die orifice. As a result, the die which is used to produce this part must be suitable to control the flow rate of metal. In this study, two different dies were used to produce this part. In first die, to control the metal flow, variable bearing length method is used. In the second die, in addition to the bearing length method, a feeder is used in the narrow channels. From the experimental and numerical results, it was found that the first die is not good enough for manufacturing of this part. Because, the first die was not able to control uniform metal flow rate through the die orifice during the extrusion process. This drawback causes the die cavity to remain empty at the sharp corners which results a low quality and low dimensional accuracy in the product, especially in narrow channels. The numerical analysis results have shown that, the second die performance was much better than the first one. It was able to control uniform metal flow rate which causes high quality products.

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A lot of research has been done to study force-tractions and couple-tractions acting on the surface of solid and fluid elements. Navior-Stokes equations have been developed based on these researches in the domain of fluid mechanics. However, a number of researchers have emphasized that the Navior-Stokes equations are not sufficient and they should be modified because regardless of couple-stress effects. In this paper, after presenting couple-stress theory, two flow geometry between two concentric pipes and flow over porous wall are considered and the behavior of them are compared with classical case. It has been shown that the force-stress tensor is not symmetric by calculating two components of the force-stress tensor for flow between two concentric pipes. In addition, it can be considered that length scale is an effective parameter on small scale flow by calculating flow velocity profile for these two geometries and by comparing them with classical solution. However, the effects of length scale on the velocity profile and the flow rate decrease with increasing geometrical scales of the problem. These results can be used to study fluid flows with small-scale characteristics such as biofluids, lubrication and microelectromechanical systems

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In this paper, an optimization-based nonlinear control strategy is applied to air path control of a turbocharged diesel engine. For this aim, the air-fuel ratio (AFR) and the pressure of exhaust manifold are controlled by calculating the air mass flow rates of turbocharger and exhaust gas recirculation. Controlling AFR which affects engine power, fuel consumption and exhaust emissions, is carried out by calculating the air mass flow rate with the assumption of known fuel path. For air path modelling, the mean value model which is a suitable method with low computational time is used to achieve the air path equations. Air mass flow is calculated by the developed control laws and applied by the turbocharger and exhaust gas recirculation. In the proposed control method, the nonlinear system response is firstly predicted by Taylor series expansion and then the optimal control law is developed by minimizing the difference between the desired response and the actual response. To compare the performance of the proposed optimal controller, a sliding mode controller has been also designed. The simulation results show that the rate of air mass and the pressure of exhaust manifold are close to their desired values and consequently the AFR is well controlled. Therefore, the designed controller with optimal inputs can successfully cope with the nonlinearities existing in engine dynamics model.

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The pressure-time method is a flow rate measurement technique generally employed in hydropower plants to evaluate the efficiency of hydraulic turbines. The 1D numerical simulation incorporating the finite volume method is employed to evaluate the method. The results are compared with the experimental data. The flow is simulated inside a straight pipe with Reynolds number Re=6.76×〖10〗^6. The flow rate reduction curve is employed for the simulation of the deceleration part of the flow, before valve closure, in the pressure-time method. The effective parameters on the flow rate calculation including the friction losses and the definition of the final time of the valve closure are studied in detail. The increase in the accuracy of the flow rate calculation is a function of the increase in the accuracy of the friction loss calculations. The effect of several friction factors proposed for the evaluation of the unsteady flow is studied on the accuracy of the flow rate calculation. The Pezzinga friction factor shows the least error in the flow rate calculation. The available methods to find out the final time of integration still show a large error. A new method is proposed for the flow rate estimation without any need to have the exact time of the valve closure with an acceptable accuracy.

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The aim of the current research was to investigate the effect of pressure gradient in the gap on morphological and geometrical characteristics of the powder synthesized by electrical discharge method and optimizing it. Electrical discharge is a modern and high performance approach towards yielding ultrafine powder. The pressure gradient was inducted by pulsed flushing using various current flows of deionized water and ethanol and, two rods of graphite and tungsten were used to yield tungsten carbide powder. Scanning Electron Microscope (SEM) images show that the powder contains both electrodes' material and is within nano range. Furthermore, the SEM images demonstrate that with increasing pressure gradient there is a decline in powder agglomeration. Particle Size Analysis (PSA) results reveal that the mean particle size of the powder produced in deionized water and ethanol is approximately 100nm and the particles produced in ethanol are smaller. Moreover, the size of the crystals of the synthesized particle are within 30-44 nm range. X-ray diffraction showed that the dominant phases of the powder in ethanol and deionized water are WC1-x and W2C respectively. Overall, the results prove that causing steep gradient in the gap, it is possible to synthesize geometrically uniform powder with decent production rate.

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A natural circulation loop receives heat from a high-temperature source and rejects it to a low-temperature source without using a mechanical pump. Single phase natural circulation loop has been applied in many industrial systems for cooling. The heat transport capability of natural circulation loops (NCLs) is directly proportional to the flow rate that it can generate. To establish the heat transport capability of a natural circulation loop, it is essential to know the flow rate. Friction force and gravitational force are balanced with each other along the loop at steady state. In this paper, firstly the governing equations have been written for a natural circulation loop. Then the governing equations have been rewritten in the dimensionless form. Then, effects of heater length, cooler length, tube diameter, loop height, loops inclination angle, the distance of heater from the right side or left side, the distance of cooler from right or left sides and power of the heater on the loop mass flow rate and loop temperature distribution have been investigated. The results show that increasing of loop height, loop diameter and power of heater increase the mass flow rate. Also, increasing or decreasing of heater length, has no effect on the mass flow rate, whereas increasing of loop inclination angle decreases the mass flow rate. In this study, the friction coefficient is considered as continues for all regimes. In addition, the position of the heater and cooler has been unsymmetrically investigated.

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Field observations of flow measurement difficulties using portable ultrasonic flow meters are reported in this work. Accordingly, pipe wall thickness and sensors’ spacing were identified as two important sources of the in-situ flow measurement inaccuracies. Experimental tests were accomplished to evaluate the effect of input parameters on the performance of the portable ultrasonic flow meters. Iron and Unplasticized Poly Vinyl Chloride (UPVC) pipes of the outer diameters of 3, 4, and 8 inches were tested. For all tested cases, the pipe wall thickness increase would affect the ultrasonic performance more than the cases with the wall thickness decrease. A mixed effect of the sensors’ spacing was observed for the changes in pipe material/dimensions. Finally, a correction equation was proposed to improve the flow measurements.