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Ventricular Fibrillation (VF) is the major cause of triggering sudden cardiac death (SCD). Efficient prediction of ventricular fibrillation is very important for clinical purpose, as this is the most serious cardiac rhythm disturbance and can be life threatening. A reliable predictor of an imminent episode of VF, could be incorporated in an implantable cardioverter defibrillator (ICD) would be capable of delivering preventive therapy. The aim of this study is to investigate the possibility of predicting VF from surface electrocardiogram (ECG) signal by beat to beat tracing of the signal and using a dynamic thresholding method. As VF arises from the lower pumping chambers of the heart (ventricles), it is expected to find some changes in the ventricular activity part of the ECG signal before its occurrence. In this paper, we focused on the T-wave of ECG signal which shows the repolarization of ventricles and tried to present an online predictor by finding an entropy-based pattern in T-waves of ECG signal that can effectively maps the irregularity of this wave before VF. We have also used an Empirical Mode Decomposition (EMD) method to reduce the high frequency noises of T-waves before predictive index extraction in each beat. We found that proposed predictive pattern can be considered as a useful index for probability occurrence of VF. It reached the sensitivity of 89% and specificity of 95% in online VF prediction method. Presented method is simple, computationally fast and has high prediction quality and hence is well suited for real time implementation.  

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In this work, adhesion system for wall climbing robots, known as "vortex attractor", has been studied analytically, numerically and experimentally. Vortex attractor system consists of the following components: vortex cup, centrifugal fan and an electrical motor. In this design, vortex flow which is generated at the fan impeller eye produces a considerable suction pressure. Knowing this fact that the air flow is trapped inside the cup, the suction force increases and also power consumption is reduced. Firstly, an attractor system is manufactured considering necessary measurement facilities. The effect of different parameters such as rotational speed and gap between system and surface on system performance is investigated. Numerical simulation of vortex attractor system is performed using CFX software. The numerical results were verified through grid independency and validated with comparison with those obtained from measurements. In the next step analytical study is carried out using Rankine vortex. Experimental results show that as gap increases, power consumption increases. In the case of vortex attractor stick to surface, repulsive force is observed. Analytical results show that generated force and pressure are proportional to square of rotational speed.

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Nowadays, using renewable energies, specifically ocean wave energy, is of importance in the world. One of the methods by which this energy can be harnessed is through using axial turbines with low head. In this study, performance of an axial turbine ocean wave of Wells type installed on the floating oscillating platform has been numerically studied. The length of the oscillating bed is equal to the wave length of the ocean upon its center the Wells turbine has been installed. This design causes the inlet flow rate to be doubled, which will in turn increase the power. In this way, the governing equations include continuity and momentum equations have been solved considering SST turbulence model. Furthermore, the acquired results have been verified through mesh independency analysis and have been validated by comparison with the available experimental data. The results show that with decreasing the clearance and setting it to 2% of the chord length value, the maximum efficiency, which is approximately 35%, will be gained. Moreover, by varying the angles from 0 to 12° with respect to its tip, achieve higher efficiency in different velocity ratios. On the other hand, employing a blade with variable profile will lead to postponing stall phenomena. Moreover, employing multistage turbines with guide vanes at the mid stage can improve efficiency by 9 percent.

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Intense pressure pulsations, which are caused by the vortex rope in the runner cone and the draft tube of pump-turbines, result in vibrations and noise under partial load conditions in turbine mode and also reduce the machine’s efficiency. The most common method for reducing these fluctuations is injecting air through the shaft. This method has some disadvantages such as, negative influence on efficiency, high cost, and technical difficulties. In the present paper, the concept of locating grooves on the conic surface of runner has been investigated. In this regard, the runner and the draft tube geometry has been designed according to the specifications and the accessible information of Siah-Bishe project. Afterwards, the 3-dimensional flow field has been solved numerically, using Ansys CFX package. The numerical results have been verified by investigating their independency from grid size and comparing the results with experimental ones. Maximum difference between the proposed and the existing design’s performance has been less than 2 percent. The results indicate that locating grooves on the conic surface of the runner results in an increase in the flow velocity beneath the runner cone. Moreover, pressure pulsations have been decreased and the low-pressure area at the beginning of the draft tube shrank. The maximum amount of decrease in pressure pulsations has been recorded in two opening positions of the guide vanes (lower than 60% and more than 90% of design point). In addition, maximum efficiency drop in the revised design has been less than 0.3 percent.

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Samples of grass pea seed (Lathyrus sativus) were prepared and analyzed for some chemical composition and as well for their anti-nutritional factors. The rumen degradability coefficients and post ruminal digestibility of dry matter and crude protein of unheated vs. oven heated samples were determined, employing in situ and in vitro techniques. Results indicated that grass pea seed contained a considerable level of crude protein (36%). The process of heating reduced (P< 0.05) tannins and Oxalyl DiAminoPropanoic acid (ODAP) content in grass pea seeds. Heat processing, especially 3 hours of heating, increased (P< 0.05) the slowly degradable fractions of the seed. Ruminal disappearance of DM and CP occurred at a lower rate (P< 0.05) for the heated grass pea seed than for the unheated seed. Heat processing did not affect the production of some such nutritional parameters (estimated through gas production method) as DOM, ME, NE_L, SCFA and MP production (P> 0.05). It was concluded that grass pea seed was of a substantial potential as a protein source in ruminant nutrition with its heat processing resulting in positive effects on its DM and CP digestibility.

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Utilization of hydro- power as renewable energy source is developed in the world now significantly. Using very low head axial turbines in rivers is one of ways for obtain this energy. In this research, design and optimization of an axial hydraulic turbine with very low head(2.9m) was done. The first step in the optimization of turbine is generation a suitable initial geometry. For this purpose one dimensional design approach based on Euler law was used. Development of computation algorithms is very efficient and suitable in hydraulic turbine design and performance investigation. In this research mesh was generated with mesh-ANSYS software and then the default domain was simulated by solving the 3-D Navier Stokes equations through the runner passages in the CFX software. Optimization geometry is obtained by optimization of Drag to Lift coefficient ratio for different blade midspans. For parameterization of airfoils, the “CST” method and for extraction of flow characteristics of airfoils XFOIL software were utilized. Then airfoil coefficients by minimization of Drag to Lift ratio with fminsearch algorithm in MATLAB software were corrected. The results show that the efficiency in design point is increased about 2.4%.

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Recently, use of PAT (pump as turbine) in mini hydro power plants (< 500 Kw) has increased due to its lower cost, easy installation and maintenance feasibility. Since the overall efficiency of this machine is lower than conventional turbines, the use of these machines in large plants are not economically recommended. In this study, the effect of geometrical parameters of impeller on PAT performance is investigated. In the present research, the geometries of components of an available commercial pump was scanned and modeled. To make the study more feasible, Impeller was redesigned in CFturbo software. Commercial software of ANSYS CFX 15.0 was used to simulate the fluid flow within PAT. Numerical results are in good agreement with existing experimental data. Three main parameters, namely, blade number variations, leading edge shapes and splitter blades were comprehensively investigated. Result shows that using 7 blades, rounding leading edge with suction side chamfer and 20% length splitter blades improve the efficiency. Finally, the most appropriate geometry with parameters of 6 blades, rounded trailing edge with suction side chamfer and 20%splitter blades is recommended for achieving the highest efficiency that can boost it up to 2%.

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Small scale hydraulic power plants equipped with very low head (VLH) axial turbines can be considered as a novel approach to extract energy from rivers and canals. In this study, design process and numerical simulation of a prototype of a VLH turbine is done. The selected turbine generates 450 kW power at the head of 2.6 m. In order to generate the turbine geometry using MATLAB and X-Foil, a computational code has been developed. The design process to generate finalized geometrical data of the runner blades contains a primary hydrodynamic design using Euler equation in turbomachinery, a classical approach for axial turbomachinery design and selection of hydrofoils with appropriate lift coefficient. Using the geometry and structured mesh generated by Turbo Grid for discretization of governing equations, the numerical simulation was accomplished by ANSYS CFX. Simulation results of different opening angles of the runner blades are presented for the turbine system including runner and guide vanes. Also, cavitation possibility is studied in various opening angles and discharges. The results demonstrate that the hydraulic efficiency of the VLH turbine is approximately 89% where the opening angle of the runner blades is at the design point. Moreover, cavitation does not occur at the design point. However, at flow rates larger than the nominal flow rate, and at opening angles larger than the design point cavitation at the leading edge is possible

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Today, heart disease is the first cause of death in the world. The heart pump is a mechanical device used to help heart patients. The blood of people who use the heart pump, due to being in contact with the mechanical device, suffers from damage such as thrombosis and hemolysis. When the heart pump starts from a resting state, its angular velocity increases in a short period of time, and then operates at a constant rate .Transient blood flow analysis is very valuable when the pump speed is changing. In this paper, the flow of fluid inside the heart pump and the amount of damage to the red blood cells were analyzed numerically. In this analysis, the effect of shear stress caused by the blades of the pump into the red blood cells was also investigated. Total pressure and flow rate at the inlet and outlet of the pump as well as relative velocity changes of the pump inside the pump and its evolution were discussed. Finally, the hemolysis created during the simulation period was calculated. In the study, it was found that the pump head and flow rate start to increase when it starts working, and also hemolysis analysis showed that the heart pump during starting period causes serious damage to the red blood cells and the possibility of rupturing the red blood cells in this short period of time is high.

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Regenerative pumps are pumps with a very low specific speed. The main characteristic of regenerative pumps is the ability to produce high heads at low flow rates.  In this article, numerical and experimental methods have been used to analyze and improve the performance of regenerative pumps and also to investigate the effect of leakage flow around the impeller. In order to validate, an experimental test circuit of regenerative pumps has been designed and built. The comparison of the numerical and experimental results have a good agreement, which indicates the high accuracy of the numerical simulation. Based on the results of the study, we conclude that increasing the geometric thickness of the leak leads to an increase in mixing the high-pressure fluid of the outlet nozzle with the low-pressure fluid of the inlet area, leading to a decrease in the generating head generated by the regenerative pump. The performance parameter of efficiency will also decrease significantly by increasing the geometric thickness of the leakage to 0.4 mm compared to the original geometry with a leakage of 0.26 mm. On the other hand, reducing the leakage thickness to 0.2 mm will lead to the improvement of the functional parameters of the head and the efficiency of the reproducing pump. Also, the ideal geometry without leakage has been introduced and calculated for the maximum and theoretical limit of head and efficiency parameters.