1 1027-5940 Tarbiat Modares University 28599 Modeling of an Evacuated Tube Solar Cooker and Investigation of Weather Parameters Effect Hosseinzadeh M. b Mirzababaee S.M. c Zamani H. d Faezian A. e Zarrinkalam F. f b Food Industry Machineries Department, Research Institute of Food Science and Technology, Mashhad, Iran c Food Industry Machineries Department, Research Institute of Food Science and Technology, Mashhad, Iran d Food Industry Machineries Department, Research Institute of Food Science and Technology, Mashhad, Iran e Food Industry Machineries Department, Research Institute of Food Science and Technology, Mashhad, Iran f Mechanical Engineering Department, Engineering Faculty, Mashhad Branch, Islamic Azad University, Mashhad, Iran 1 7 2019 19 7 1573 1584 25 12 2018 06 02 2019 In this study, the performance of an evacuated tube solar cooker analytically investigated. For this purpose, the heat transfer mechanisms in different components of the solar cooker is evaluated. The main aim of this article is to investigate the important parameters of the evacuated tube solar cooker in different weather conditions using the validated analytical model. The studied parameters are: wind speed, ambient temperature, and input solar radiation. The experiments performed at the Research Institute of Food Science and Technology, Mashhad, Iran (Latitude: 36° and Longitude: 59°). The results reveal that the presented analytical model is an accurate model that can be used in the paramedic analysis of the evacuated tube solar cooker. Moreover, in the reference weather conditions, the lost heat contains only 12.22 W of the absorbed solar radiation (137.51 W). Therefore, about 8.89% of the absorbed solar radiation is lost. Based on the results, the temperature of outer surface of the cooker is only 3.64 °C higher than the ambient temperature due to the vacuum between the tubes. In addition, the evacuated tube solar cooker has proper performance in various weather conditions. Increasing the ambient temperature from 5 °C to 35 °C enhances the solar cooker efficiency by 0.65%.  
24692 Optimal Control Algorithm Design for the Microfluidic Channel Network Droplet Generation with Output Feedback Delay Ebrahimi dehshalie M. g Menhaj M.B. h Karrari M. i g Electrical Engineering Faculty, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran h Electrical Engineering Faculty, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran i Electrical Engineering Faculty, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran 1 7 2019 19 7 1585 1590 02 09 2018 02 12 2018 In this paper, the optimal control algorithm design is proposed for droplet generation. In the proposed algorithm, the redundancy in the microfluidic channel network for droplet generation is used to the optimization setting in order to determine volume flow rate of fluid for each input channel; an optimization problem is proposed for minimizing the volume flow rate of fluid such that the droplet formed in the outlet channel is produced at the desired size. Also, due to the importance of estimating the system state, the design of the Luenberger observer (reduced order observer) has been developed. Then, the proposed scheme is robust against output feedback delay with respect to the optimal LQR control structure for tracking the desired value. While designing for the observer and controller sections, the delays in the measurement of the output feedback are considered, and the sustainability analysis for each of the sections has been performed due to the fixed delay in the output feedback. Output feedback is a measurable variable of the input volume flow of each channel. Finally, the optimal control algorithm of droplet generation for a microfluidic structure with a T shape has been stimulated. 21024 Investigation of Macroscopic Fracture Surface Characteristics of API X65 Steel Using Three-point Bending Test Hashemi H. j Hashemi S.H. k j Mechanical Engineering Department, Engineering Faculty, University of Birjand, Birjand, Iran k Research Center on Pipeline & Related Industries, University of Birjand, Birjand, Iran 1 7 2019 19 7 1591 1600 19 05 2018 19 03 2019 The API X65 steel (with a minimum yield strength of 65ksi equivalent to 448MPa) is one of the most common types of pipe steels in the transportation of natural gas in Iran. By studying the ductile and brittle fracture areas at the fracture surface of this steel, we can show the quality of this type of steel. In the present study, macroscopic fracture surface characteristics in three-point bending test specimen are studied (based on the geometry and standard notch of drop-weight tear test specimen). Test specimens were machined from an actual steel pipe of API X65 grade with an external diameter of 1219 mm (48 inches) and wall thickness of 14.3 mm. Due to the quasi-static test conditions and speed of the machine's jaw (0.1 mm/s), the test was carried out on base metal specimens with machine chevron notch of 15, 10, and 5.1 mm depth, respectively, that was controlled with changing location. By applying the test load, cracking initiated from the notch root in each specimen and continued without crack specimen (ligament). At the end of the test, test specimens were cooled by liquid nitrogen and were broken in a brittle manner. In this paper, after investigation of the failure mode and the crack expansion in the standard specimen, investigation of macroscopic fracture surface characteristics was conducted by optical microscopy. By observing the fracture surface, different features such as thickness variation, shear regions (ductile fracture), cleavage fracture, shear lips, inverse fracture, and brittle fracture were studied. Having above 85% shear area, the ductile fracture of specimen was confirmed. 18361 Experimental Study and Visualization of Particle/Bubble Collision in the Presence of Fluid Mohammadi M. l Nazari M. m Kayhani M.H. n l Fluid Mechanics Department, Mechanical & Mechatronics Engineering Faculty, Shahrood University of Technology, Shahrood, Iran m Fluid Mechanics Department, Mechanical & Mechatronics Engineering Faculty, Shahrood University of Technology, Shahrood, Iran n Fluid Mechanics Department, Mechanical & Mechatronics Engineering Faculty, Shahrood University of Technology, Shahrood, Iran 1 7 2019 19 7 1601 1611 02 04 2018 23 12 2018 Flotation is the most important method for the separation of minerals. A key element of recovering valuable minerals through flotation is particles/air bubbles interaction in water. In the present paper, an experimental approach is proposed to study the collision of fixed bubble and particles. The results of this investigation are widely used in the application of plastic particle flotation. In this paper, by creating a bubble with a diameter of 5.5 mm through injection pump in fixed fluid, the plastic particles (with a diameter of 1.5 mm) are released on the surface of the bubble. The polar position of the particles on the bubble surface is changed by variations of the falling height and increasing the height of release leads to a decrease in the polar position of collision on the surface of the bubble. The initial collision angles at the release heights of 18.68mm, 13.36mm, and 10mm are 18.01, 15.15, and 18.8 degrees, respectively. In this study, the effect of forces of drag, capillary, pressure, weight, and buoyancy on the attachment and detachment of the particle on the surface of the bubble has been reported. Due to the low sliding velocity of the particle on the surface of the bubble, the drag force is negligible at the attachment and detachment case and floating and gravity forces are also constant. The main roles in effective forces of collapse are capillary and pressure forces. The effect of the three-phase contact line on the capillary and pressure forces is also analyzed, which is one of the innovations of the present study. 21547 Numerical Simulation of the Effects of Surface Roughness on Nucleation Site Density of Nanofluid Boiling Alimoradi H. o Shams M. p o Mechanical Engineering Faculty, K. N. Toosi University of Technology, Tehran, Iran p Mechanical Engineering Faculty, K. N. Toosi University of Technology, Tehran, Iran 1 7 2019 19 7 1613 1622 31 05 2018 14 11 2018 In this research, a numerical scheme for subcooled flow boiling with water based fluid in a channel with a hot spot was developed. The effect of nanoparticles was studied in the subcooled flow boiling. Alumina nanoparticles were used for the protection of nanofluid. The properties of nanofluid are assumed to be temperature independent. The mixture of nanofluid is studied by using Eluer–Eluer approach. In addition to considering the variable properties of temperature in this study, a model for the density of the nucleation site was used, which is the surface roughness and sedimentation rate of the nanoparticles. After verifying the model, the nanofluid boiling was modeled, using 4 roughnesses of 25, 50, 75, and 100 nm. Changes of bubble dynamics parameters were investigated in different heat fluxes and roughnesses. According to the results, it was found that with increasing surface roughness, the surface temperature drop and the density of the nucleation site density increased. Also, bubble departure diameter is increased and bubble detachment frequency is decreased by increasing surface roughness. Moreover, the results shows that bubble detachment diameter is increased by increasing the heat flux and bubble detachment waiting time. 18451 Effect of Dynamic Stability Derivatives Coefficients on the Design of Operational Parameters of the Actuator in an Underwater Robot Mirzaei M. Taghvaei H. “Hydro-Aeronautical Research Center” and “School of Mechanical Engineering”, Shiraz University, Shiraz, Iran School of Mechanical Engineering, Shiraz University, Shiraz, Iran 1 7 2019 19 7 1623 1632 04 04 2018 31 12 2018 Determining a dynamic model for an underwater robot is of great importance in design of guidance and control system. Researchers always need a complete knowledge about hydrodynamic stability derivatives coefficients of vehicle with sufficient accuracy to design a successful control system for underwater vehicles. The selection of proper actuator in control system is important on the global performance of the system and the costs of the project. Usually, the effect of dynamic stability derivative coefficients is not considered in the design of actuators; therefore, in the present study, it is tried to investigate the effect of these coefficients in the design of actuators. For this purpose, firstly, the equations of motion for an underwater robot are presented. Then, hydrodynamic coefficients that contains static and dynamic coefficients are determined, using a rapid computational code and, then, the effect of hydrodynamic stability derivatives coefficients on the operational dynamic parameters of vehicle such as the bandwidth of the system dynamics and its role in the control system are considered. Finally, the selection of appropriate actuator for the underwater robot and the effects of natural frequency of actuators on the system performance are studied.   18707 Waste Heat Recovery Rankine Cycle Based System for Heavy Duty Trucks Rastgar R. Amidpour M. Shariati Niasar M. Energy System Engineering Department, Mechanical Engineering Faculty, K. N. Toosi University of Technology, Tehran, Iran Energy System Engineering Department, Mechanical Engineering Faculty, K. N. Toosi University of Technology, Tehran, Iran Energy & Environment Department, Niroo Research Institute, Tehran, Iran 1 7 2019 19 7 1633 1643 08 04 2018 07 01 2019 Despite recent improvement in energy efficiency of diesel engines, more than 50% of the energy input is lost as waste heat in the form of hot exhaust gases, cooling water, and heat lost from hot equipment surfaces. Exhaust pollution from internal combustion engines can potentially result in severe damages on earth atmosphere, including ozone depletion, global warming, and significant health problems. Waste heat recovery based on Rankine cycle has been identified as a potential solution to increase the energy efficiency and consequently to reduce the engine emissions. In this rather low cost technology, waste heat is recovered in a Rankine cycle, aiming to convert mechanical power into electrical power. Output electrical energy is stored in a battery and can be used in electric usages. In this paper, the possibility of using the exhaust heat recovery system without utilizing the heat of other recyclable materials has been investigated, using the organic Rankine cycle (ORC), in order to increase the efficiency of the diesel engine of the bus. Depending on amount of achievable heat of exhaust, in some performance point of diesel engine, the amount of fluid flow rate and output power of Rankine cycle was calculated. Our results exhibit 5.1 KW increase in the diesel engine power resulting in 1.12% increase in energy efficiency in engine part load condition. The output mechanical power from the micro-generator is converted to electrical power and is stored in an energy storage system. The storage energy can be utilized to supply power for electrical equipment such as fans, bulbs, and also phone chargers of passengers.   27652 Experimental, Numerical, and Analytical Study of a Droplet Impact on Parallel Fibers Safavi Mohamad Nourazar S. Faculty of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran Faculty of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran 1 7 2019 19 7 1645 1653 29 11 2018 07 01 2019 The statics of droplet hanging from the parallel fibers and the dynamics of droplet impact on the parallel fibers are investigated using high-speed imaging and volume of fluid numerical simulation. Experimental results show for the parallel fibers, the maximum volume of the droplet, which is able to hang statically from the fibers is measured to vary between 1.85 to 1.9 times of the one measured for a single fiber. The dynamics of droplet impact have been studied by varying the radius of the impacting droplet, the fibers radius, and the distance between the fibers. The threshold velocity of droplets by fibers has been obtained both experimentally and numerically with the fluid volume method. The results show that by increasing the impacting droplet radius and decreasing the fibers radius, the threshold velocity of droplet capture decreases. The maximum threshold velocity of droplet capture with parallel fibers varies in the range of 1.5 to 1.8 times of the threshold velocity of capture with a single fiber. The maximum threshold capture velocity of droplets occurs where the distance between fibers is in the range of 0.35 to 0.5 times of impacting droplet diameter. The threshold capture velocity on parallel fibers is also obtained analytically, using the energy balance method. The results of the analytical solution are in a fair agreement with experimental data and numerical simulation results. 26135 Experimental Study of Damage Detection in Beam Using Dynamic Excitation System and Wavelet Packet Transform and Energy Rate Index Kohdaragh M. Lotfollahi Yaghin M.A. Etefagh M.M. Mojtahedi A.R. Civil Engineering Department, Engineering Faculty, Malekan Branch, Islamic Azad University, Malekan, Iran Civil Engineering Faculty, University of Tabriz, Tabriz, Iran Mechanic Engineering Department, Mechanic Engineering Faculty, University of Tabriz, Tabriz, Iran Civil Engineering Faculty, University of Tabriz, Tabriz, Iran 1 7 2019 19 7 1655 1662 14 10 2018 07 01 2019 Most of structural failures are because of break in consisting materials. Beginning of these breaks is with crack, whose extension is a serious threat to behavior of structure; so, the methods of distinguishing and showing cracks are the most important subjects, which are being investigated. In this article, by experimental, a new smart portable mechanical system to detect damage in beam structures by wavelet packet energy rate index is introduced. At first, acceleration-time history is taken from the points of the simple support beam, using the accelerometer sensors, and then these signals are decomposed into packet wavelet components and the energy rate index is calculated for each, which is named by Wavelet Packet Energy Rate Index (WPERI). The results indicate that these values are a sensitive and accurate index for the identification of the cracks. 20555 1D- 1D Modeling of High Pressure PEM Electrolyzers for Hydrogen Production Hendooie L. Shafaghat R. Ramiar A. Dardel M. Esmaili Q. Mechanical Engineering Faculty, Babol Noshirvani University of Technology, Babol, Iran Mechanical Engineering Faculty, Babol Noshirvani University of Technology, Babol, Iran Mechanical Engineering Faculty, Babol Noshirvani University of Technology, Babol, Iran Mechanical Engineering Faculty, Babol Noshirvani University of Technology, Babol, Iran Management & Technology Applications School, Amol University of Special Modern Technologies, Amol, Iran 1 7 2019 19 7 1663 1674 06 05 2018 24 12 2018 One of the most important factors in decreasing the lifetime and inappropriate performance of PEM electrolyzers is the non-uniform current distribution on membrane surface. Since the smoothest distribution of species and water leads to optimal current distribution, in this research, a 1D- 1D model has been developed that explores the distribution of species and water, and finally the current distribution in layers and determines the optimal performance conditions of the high PEM membrane electrolyzers. In this model, the pressure is assumed constant throughout the channel, the cell temperature is constant, and the membrane is fully hydrated. The length of the anode and cathode channels is divided into 20 equal parts. By simultaneously solving the equations along the channel and perpendicular to it in each section, the distribution of species and current are obtained. The result showed that by increasing the average flow density, the flow distribution is smoother along the channel and, with increasing water flow, the current distribution is smoothed, but it has little effect on the polarization curve. Fick's effect on the distribution of species at the interface between the membrane and the gas diffusion layer has been investigated. Finally, the effect of thickness on the polarization curve is determined. By increasing the thickness of the membrane and the electrodes, the function of the system decreases. 24652 Investigating the Effect of Different Sensors on the Observer Performance in Vehicle Suspension System Based on the Observable Degree Analysis Falahati Nodeh T. Mirzaei M. Babazadeh Mehrababni E. Khosrowjerdi M.J. Mechanical Engineering Department, Mechanical Engineering Faculty, Sahand University of Technology, Tabriz, Iran Mechanical Engineering Department, Mechanical Engineering Faculty, Sahand University of Technology, Tabriz, Iran Mechanical Engineering Department, Mechanical Engineering Faculty, Sahand University of Technology, Tabriz, Iran Electrical Engineering Department, Electrical Engineering Faculty, Sahand University of Technology, Tabriz, Iran 1 7 2019 19 7 1675 1684 27 12 2018 04 02 2019 In this paper, the effect of different sensors on the observer performance of vehicle suspension system is investigated. For this purpose, the concept of observable degree analysis is used to quantitatively measure the observability for different sensor choices. A new method, for determining the observable degree of linear time invariant (LTI) systems has been developed on the basis of distance of system from set of similar unobservable systems. A long distance is equivalent to a strong observability and a short distance is equivalent to a weak observability. The zero distance means that the system is unobservable. Since the distance to different unobservable modes can be determined separately, a comprehensive investigation of system observability and the effect of different sensor choices on the observer performance can be provided. In the following, the observable analysis of the suspension system was performed based on the proposed method and the effect of different outputs on the observer performance has been investigated. The results show that when the observable degree is increased for a specific sensor, the observer gain is decreased and consequently the sensitivity of observer relative to the noise and measurement errors is decreased. The increased accuracy of observer demonstrates a good conformity between observable degree analysis and observer performance. Also, a comparative study showed that, contrary to previous criteria that only considered a certain aspect of observability, the proposed method is more comprehensive and realistic, and the results obtained from the previous criteria can easily be achieved through the proposed method.   19173 Numerical Study of Energy Harvesting of Vortex Induced Vibration Phenomenon of Circular Cylinder with Various Sectors at Low Reynolds Number Rafati Zarkak M. Barati E. Abolfazli Esfahsni J. Mechanical Engineering Department, Engineering Faculty, Khayyam University, Mashhad, Iran Mechanical Engineering Department, Engineering Faculty, Khayyam University, Mashhad, Iran Mechanical Engineering Department, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad, Iran 1 7 2019 19 7 1687 1695 19 04 2018 05 01 2019 In this study, the geometrical effect of circular cylinder with different sectors on energy harvesting of vortex induced vibration is investigated numerically. According to Von Karman vortex shedding phenomenon, the flow passes over a bluff body and as the results create vibration, can use this phenomenon with energy extraction and converting it into desired energy. In this paper, the focus was on discovering a cylinder geometry with more vibration than the base cylinder (circular cylinder); for this purpose, circular cylinder with different sectors, including  ratio of 0.5, 0.6, 0.7, 0.8, 0.9, and 1 in two direction of arches frontal (AF) incoming flow and flat frontal (FF) incoming flow have been studied at Reynolds numbers of 100 and 200. Investigations have been carried out in the fluid and vibration field. In the fluid field, the aerodynamics forces are obtained on the cylinder with the help of computational fluid dynamics (CFD) and in the vibration field, by writing program in the Maple software, the displacement of the cylinder and, finally, recoverable potential power of the fluid were calculated. The results show that, at Reynolds numbers of 100 and 200, respectively, circular cylinder with and  sectors in the placement direction of FF get the maximum extraction power of fluid and compared to the circular cylinder at Reynolds numbers of 100 and 200, respectively, 3.5 and 5.3 more times power harvesting. Also, in the same sectors cylinder, the cylinder with FF placement direction always has more power generation than the cylinder with AF placement direction. 18638 Comparison of Instantaneous Properties Extraction Methods and Execution of Optimal Empirical Mode Decomposition on Faulty Ball Bearing Experimental Data Momeni Massouleh S.H. Vesaghati Javan M. Hosseini Kordkheili S.A. Department of Aerospace Engineering, Sharif University of Technology, Tehran, Iran Department of Aerospace Engineering, Sharif University of Technology, Tehran, Iran Department of Aerospace Engineering, Sharif University of Technology, Tehran, Iran 1 7 2019 19 7 1697 1709 07 04 2018 10 01 2019 Empirical mode decomposition (EMD) is one of the new methods for decomposing a signal into its constituent components. The existence of multiple error sources has led to activities to eliminate or mitigate their effects. In this research, one of the major problems of EMD for the separation of noise-polluted signals, namely, mode mixing problem has been studied. To solve this problem, bandwidth EMD has been used, which enhances the EMD method and processes speed and greatly prevents mode mixing problem. Also, among the available methods to extract the instantaneous properties, the proper pair of instantaneous properties identification and signal normalization method is presented by an example. To investigate the efficiency of the bandwidth EMD method, using the optimal method of extracting the instantaneous properties, the experimental data of a faulty bearing have been studied and the instantaneous properties of both EMD method and the bandwidth EMD method have been extracted. Using the coefficient of variation criterion, it is shown that the bandwidth EMD method has a higher resolution and better results than EMD method. Finally, using information of decomposed white noise by EMD, the noise isolation quality of the original data is examined, which indicates a better decomposition of the results of the bandwidth EMD method. 23371 Numerical Analysis of the Heat Sink Effect of Blood Vessels on Hepatic Radiofrequency and Microwave Ablation Maaref Y. Pakravan H.A. Jafarpur Kh. Thermo-Fluids Department Department, Mechanical Engineering School, Shiraz University, Shiraz, Iran Thermo-Fluids Department Department, Mechanical Engineering School, Shiraz University, Shiraz, Iran Thermo-Fluids Department Department, Mechanical Engineering School, Shiraz University, Shiraz, Iran 1 7 2019 19 7 1711 1720 22 07 2018 05 01 2019 During the last 3 decades, different therapeutic methods have been used for cancer treatment. Hyperthermia is one of these methods, which destroys the tumor cells with applying temperatures about 41-46°C. Thermal ablations of hepatic tumors near large blood vessels are affected by the heat sink effect of blood vessels. In this study, the heat sink effect of blood vessels on hepatic mono-polar radiofrequency and microwave ablation was investigated. The simulation is performed by numerical solution of bio-heat transfer equation with equations of electrical current or electromagnetic waves. To analyze the heat sink effect of blood vessels, the tissue is modeled with and without blood vessel. The fraction of necrotic tissue is determined for 3 different diameters of blood vessels including 5, 10, and 15 mm. The results show that when the applicator distance to the blood vessel is less than or equal to 8 mm, the necrotic value significantly decreases and the heat sink effect becomes important; however, for distances larger than 30 mm, the necrotic value does not change and the heat sink effect is diminished. The heat sink effect increases with blood vessel diameter due to the blood flow increase. In addition, the results indicated that the microwave ablation is less affected by the heat sink effect in comparison with the mono-polar radiofrequency. 18308 Evaluation of Rarefied Shear Flow in Micro/Nano Geometries Using Fokker-Planck Technique Rezapour Jaghargh V. Mahdavi A.M. Roohi E. Mechanical Engineering Department, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad, Iran Mechanical Engineering Department, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad, Iran Mechanical Engineering Department, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad, Iran 1 7 2019 19 7 1721 1732 31 03 2018 08 01 2019 In this article, rarefied gas flow was investigated and analyzed by the Fokker-Planck approach in different Knudsen numbers and Mach numbers at subsonic and supersonic regimes. The presented Fokker-Planck approach is used to solve the rarefied gas flows in different shear-driven micro/nano geometries like one-dimensional Couette flow and the two-dimensional cavity problem. Boltzmann's equation, and especially statistical technique of the Direct Simulation Monte Carlo (DSMC), are precise tools for simulating non-equilibrium flows. However, as the Knudsen number becomes small, the computational costs of the DSMC are greatly increased. In order to cope with this challenge, the Fokker-Planck approximation of the Boltzmann equation is considered in this article. The developed code replaces the molecular collisions in DSMC with a set of continuous stochastic differential equations. In this study, the Fokker-Planck method was evaluated in the Couette flow in the subsonic Mach number of 0.16 (wall velocity was 50 m/s) and in the supersonic Mach number of 3.1 (wall velocity was 1000 m/s), where Knudsen numbers range from 0.005-0.3. Also, the cavity flow with a wall Mach number of 0.93 (wall velocity was 300 m/s) in Knudsen numbers ranging from 0.05-20 was investigated. The results show that by increasing speed and Knudsen numbers, the accuracy of Fokker-Planck increases. In addition, despite using larger number of simulator particles, the rapid convergence and lower computational costs relative to other methods are the features of this method. 32916 Investigation of Micromechanical Behavior of Ferrite and Martensite in Dual Phase Steels Jahanara A.H. Mazaheri Y. Sheikhi M. Materials Engineering Department, Engineering Faculty, Bu-Ali Sina University, Hamedan, Iran Materials Engineering Department, Engineering Faculty, Bu-Ali Sina University, Hamedan, Iran Materials Engineering Department, Engineering Faculty, Bu-Ali Sina University, Hamedan, Iran 1 7 2019 19 7 1733 1740 13 05 2019 13 05 2019 The aim of this research was to investigate ferrite and martensite micromechanical behavior in dual phase (DP) steels. For this purpose, a low carbon steel with ferrite-pearlite initial structure was cold-rolled up to 80% and annealed at 600 ºC for 20 min and subsequently water quenched. The final processing step involved heating to the intercritical annealing region and holding for 10 min at 760, 780, 800 and 820 ºC followed by water quenching. DP steels consisting different volume fractions of ferrite and martensite and different ferrite grain size were produced. Scanning electron microscopy was supplemented by energy dispersive spectroscopy (EDS) and nanoindentation test to follow microstructural changes and their correlations to the variation in phase's hardness. Nanoindentation study of ferrite and martensite hardening response in the DP microstructures showed that the average ferrite and martensite nanohardness has significantly increased from about 181 to 281 HV10mN and decreased from about 644 to 337 HV10mN with increasing intercritical annealing temperatures from 760 to 820 ºC, respectively. Higher intercritical annealing temperatures resulted in finer and harder ferrite grains in DP microstructures. Martensite nanohardness variation with intercritical annealing temperatures is related to change in its carbon content. By applying the rule of mixtures, the calculated hardness values meet well with the experimental values. 21664 Experimental investigation of the penetration effects of opposite dual protuberances on thrust vector of a supersonic C-D nozzle Babaeyan M.R. Hojaji M. Mechanical Engineering Department, Engineering Faculty, Najafabad Branch, Islamic Azad University, Najafabad, Iran Engineering Faculty, Najafabad Branch, Islamic Azad University, Najafabad, Iran 1 7 2019 19 7 1741 1750 02 06 2018 29 12 2018 In this study, the effect of the use of dual protuberances as a thrust vector control method in a supersonic convergent-divergent nozzle with a Mach number of 2 is experimentally investigated. The nozzle total pressure in all experiments is considered constant. Air is the working fluid in these experiments. The used protuberances are two cylindrical elements that are placed in front of the flow in the divergent part of the nozzle. These protuberances are installed at 60% and 90% of the length of the nozzle divergent portion from the nozzle throat and are simultaneously applied in the main flow path. The protuberances are installed in opposite walls. Effect of changing the penetration ratio of the protuberances [H/D] on the thrust vector angle and the components of the thrust vector is obtained by measuring the forces acting on the nozzle. Also, the flow field was measured by a Schlieren system, as well as, the pressure variations on the nozzle walls were measured. The results show that the use of dual protuberances can have a significant effect on the angle of the thrust vector and increase the angle of the thrust vector up to 4.35 degrees in the implemented conditions of this study. Also, the results reveal that this method can reduce the axial component of thrust up to 5.5% in the worst case of implemented conditions.   24532 Heart Rate Measurement with Imaging Photoplethysmography Signals Using Smart Phone Sokout M.S. Heidary S.H. Beigzadeh B. Mechanical Department, Mechanical Engineering Faculty, Iran University of Science & Technology, Tehran, Iran Mechanical Department, Mechanical Engineering Faculty, Iran University of Science & Technology, Tehran, Iran Mechanical Department, Mechanical Engineering Faculty, Iran University of Science & Technology, Tehran, Iran 1 7 2019 19 7 1751 1757 28 08 2018 13 01 2019 Measuring the vital signs of human body, such as oxygen saturation, blood pressure, and heart rate is the greatest and basic stage of the diagnosis of various diseases, especially cardiovascular diseases. Various methods have been developed to measure these signs. In general, these methods are divided into invasive and non-invasive categories. Due to less damages of non-invasive methods, more attention has been paid to them in recent decades. Using mobile phone is one of the most important non-invasive approaches because of being common and accessible among people. In this article, after studying Photoplethysmographic methods and expressing theories related to this method, imaging photoplethysmography (IPPG) is used to measure heart rate. Regarding two proposed algorithms based on furies transfer and peak detection, implementation of these algorithms was done, using a camera and LED of smart phone on 20 people. Next, the heart was calculated. Finally, a comparison was made between the two methods, the results of which show that peak detection method has less error than furies transfer method. 21160 Distributed Adaptive Robust Controller Design for Consensus in Multi-Agent System Including Robot Arms with Actuator Saturation Constraint Rahimi N. Binazadeh T. Department of Electrical and Electronic Engineering, Shiraz University of Technology Electrical & Electronic Engineering Faculty, Shiraz University of Technology, Shiraz, Iran 1 7 2019 19 7 1759 1766 22 05 2018 13 01 2019 In this paper, distributed adaptive robust controller is investigated to solve the leader-follower consensus problem for a multi-agent system consisting of several single-link robot arms. In this approach, each arm is considered as an agent. The dynamical model of each arm contains known and unknown non-linear terms. Unknown terms may be due to parameter uncertainty or simplification of the model. Furthermore, external disturbances are considered in the dynamical equations of each agent. Moreover, the input signal amplitude for each agent should be limited, which is due to the upper bound of the saturation function of the input. In this paper, in order to eliminate the effect of uncertain terms, the adaptive robust approach is used in the design of control laws. In this regard, the upper bounds of uncertain terms are obtained through adaptive laws, which dramatically reduce conservatism. Furthermore, the distributed control laws are designed in such a way that all the agents reach consensus in spite of the uncertain terms and input saturation constraint. The basis of the approach proposed in this paper is based on adaptive sliding mode techniques. For this purpose, suitable sliding surfaces are proposed and distributed adaptive sliding mode controllers are designed. Finally, simulations are presented to confirm the results of theories. 23019 Vision-Based Model Predictive Control of Wheeled Mobile Robot Khonsarian R. Farrokhi M. Control Department, Electrical Engineering School, Iran University of Science and Technology, Tehran, Iran Control Department, Electrical Engineering School, Iran University of Science and Technology, Tehran, Iran 1 7 2019 19 7 1767 1777 12 07 2018 15 01 2019 In this article, a novel control of wheeled mobile robot based on machine vision is considered. One of the common methods for controlling such systems is the use of Model Predictive Control (MPC) algorithms. In these systems, the response speed of the control algorithm and the optimality of these are two basic factors for achieving the optimal performance. Also, the impossibility of achieving precise values of the robot parameters and their variation during the operation of the robot is an important challenge in the implementation of the controller, therefore, this paper focuses on real-time and robust MPC, so that it can ensure the system against uncertainties and environmental disturbances in addition to the optimal and real-time response. Hence, the optimization based on projection recurrent neural network (PRNN) has been used as an optimizer to reduce the calculation time cost. The combination of PRNN optimization with MPC leads to new formulation and constraints that are considered to be the article innovations. Finally, in order to verify the validity of the proposed algorithm, the robot passes through the corridor with the presence of obstacles, which is simulated in the V-REP software. The results show that the optimum control input speed has been increased in comparison with similar methods, and the optimal path selection by the fuzzy system in the presence of obstacles has been well suited.   25225 Numerical Investigation of Cavitation Effect on the Performance of Waterjet Propulsion System by Computational Fluid Dynamics Afshari B. Rostami Varnousfaaderani M. Mechanics Faculty, Malek-Ashtar University of Technology, Isfahan, Iran Mechanics Faculty, Malek-Ashtar University of Technology, Isfahan, Iran 1 7 2019 19 7 1779 1788 17 09 2018 19 01 2019 The numerical simulation of cavitation phenomenon in waterjet propulsion system, due to destructive effects and complicated and two-phase nature, is one of the greatest challenges in engineering and numerical modeling. Due to needing of very much cost for experimental studying this phenomenon in the cavitation tunnel, in this paper, the happening of cavitation in axial flow waterjet was simulated by computational fluid dynamics. The head, torque, and thrust due to cavitation and ignoring that were calculated in 3 flow rate values. The result showed good agreement with experimental data. One of the new studies in this paper is the investigation of the pattern of cavitation bulb forming on the tip and suction side of the rotor’s blade. Numerical simulation was performed, using the rotor and stator and with rotor only. Numerical solution is performed, using a the structured grid, the rotating reference frame, the periodic domain, and SST turbulence model in the steady form.   21524 Analysis of Variance of Residual Stress Distribution in Girth Welding of High Strength Low Alloy Steel Gas Pipeline Sabokrouh M. Farahani M.R. Engineering Faculty, Mahallat Institute of Higher Education, Mahallat, Iran School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran 1 7 2019 19 7 1789 1795 30 05 2018 19 01 2019 In this paper, the analysis of variance (ANOVA) of weld residual stress distribution (using the hole drilling strain gage method according to ASTM 837 standard) was investigated (in the hoop and axial direction of the 56-inch gas transmission). The results of ANOVA show that the best distribution curve of residual stress is the third order function (3 degree of freedom) in the distribution diagram of hoop and axial residual stresses. In this order, the p value of the hoop and axial residual stress is 0.044 and 0.001, respectively. This indicates the high reliability of the third order function. Also, the value of F and coefficient of determination of this order has an appropriate value. In addition, due to the high p value and low reliability, the 5-order approximation function is not a suitable residual stress distribution curve compared to the third order function. Order approximation functions (2 and 4) have lower reliability (higher p value) and lower F value than odd order (3 and 5). Despite having the highest freedom with the highest p (lowest reliability), the lowest F, and the lowest coefficient of determination, the second-order function, is the most inappropriate approximation function. Despite the existence of residual stress with respect to the zero experimental residual stress compared to the approximation function, the use of strain test in points far from the weld one and the base metal is not essential.   25608 Numerical and experimental investigation of current and electrode force effects on expulsion in resistance spot welding of galvanized and non-galvanized steel sheets Valaee Tale Moslem Mazaheri Yousef Sheikhi M. Malek Ghaini F. Usefifar Gh.R. Materials Department, Engineering Faculty, Bu-Ali Sina University, Hamedan, Iran Materials Department, Engineering Faculty, Bu-Ali Sina University, Hamedan, Iran Materials Department, Engineering Faculty, Bu-Ali Sina University, Hamedan, Iran Materials Engineering Department, Materials Engineering Faculty, Tarbiat Modares University, Tehran, Iran SAIPA Corporation, Tehran, Iran 1 7 2019 19 7 1797 1804 29 09 2018 19 01 2019 During the process of Resistance spot welding (RSW), some of the molten metal comes out of the interface of the two sheets, which causes contamination on the body of the cars. This named as expulsion and disrupts the staining process and reduces the safety of the workshop. In this study, by numerical and Experimental investigation, effect of welding current and electrode force on expulsion in RSW of galvanized and non-galvanized steel sheets the prediction of expulsion for both sheets was performed. Experimental results showed that with increasing the welding current, nugget diameter and weld strength increased continuously until expulsion occurrence. The resultant nugget in both types of sheets have almost similar diameter at the similar welding current however in the galvanized sheet, expulsion occurred at a larger nugget diameter. Increasing the electrode force before the occurrence of expulsion increased the nugget diameter, but then reduced the nugget diameter. The results of the investigation were found to be consistent with a modified numerical model. In this model, increase in the nugget diameter increased the force from within the nugget and accelerated the expulsion, while the electrode force was a hindrance to the expulsion. Zinc coated on galvanized steel sheets with low contact resistance and friction coefficient between zinc-zinc metal resulted in a good fit between two sheets during the welding process which according to the numerical model, causes expulsion to occur at a larger nugget diameter for galvanized steel sheets. 23908 Experimental Study of the Effect of Probe Calibration on the Mass Flow and Velocity Measurement of Hot Air at High-Subsonic Mach Numbers Ommi F. Golchin H. Aerospace Department, Mechanical Engineering Faculty, Tarbiat Modares University, Tehran, Iran Aerospace Department, Mechanical Engineering Faculty, Tarbiat Modares University, Tehran, Iran 1 7 2019 19 7 1805 1817 08 08 2018 13 01 2019 In this research, the possibility of measuring total pressure, mass flow, and velocity of a high energy flow of air at 0.6-0.7 Mach is investigated experimentally, using 6 different types of commercial sensors. For this end, a fixed area annular nozzle, mounted at the exit of micro-turbojet engine, was used. Also, a test bench with the capability of measuring total pressure, static pressure, total temperature, mass flow, RPM, and the thrust force was used. The results of the L-type sensors calibrated for such velocities indicate that the total pressure and velocity are similar, near to each other, and among the engineering precision. The largest difference between the measured and calculated mass flow was 9.1% and related to L-type probes with the length of 68mm and the outside diameter of 3mm. This difference for all other probes was less than 8%. Also, the calculated mass flow based on Rod-type probe data shows a difference of only 4.4% with the measured mass flow; so, there is a distinct difference between these two kinds of probes. Also, the measurements include useful information of the variations of main flow characteristics along the length of annular nozzle, among which the most important are an intense drop of about 29% in total pressure and about 48°C drop in total temperature. 22598 Experimental Study of the Water Absorption and Fatigue Life of PMMA/MWCNTs Nanocomposites Ebrahimzadegan A. Mohammadpour Fattahi A. Mechanical Engineering Department, Engineering Faculty, Tabriz Branch, Islamic Azad University, Tabriz, Iran Mechanical Engineering Department, Engineering Faculty, Tabriz Branch, Islamic Azad University, Tabriz, Iran 1 7 2019 19 7 1819 1825 30 06 2018 15 01 2019 Carbon nanotubes have special importance due to unique properties as an amplifier phase. In this paper, the effect of multiwall carbon nanotubes on water absorption and fatigue life of poly methyl methacrylate is investigated. To this end, nanocomposites based on polymethyl methacrylate, containing 0-1.5 weight percentage of multiwall carbon nanotubes are produced with screw and injection molding process. The morphology was studied, using scanning electron microscopy. Microscopic images examination showed that carbon nanotubes have been well released in the field of polymer. The fatigue testing of each of the prototypes was carried out under identical conditions. Based on the results of fatigue test, nanocomposite fatigue strength containing 0.5% carbon nanotubes increased than base polymer. Also, based on the results of water absorption test, the existence of multiwall carbon nanotubes in polymer field decreased absorption water of the samples.