Hydraulic and Pneumatic Systems
Lokesh Kumar; Nimai Pada Mandal
Abstract
This study focuses on the flow and pressure fluctuations of a fixed displacement radial piston pump with a valve plate with silencing grooves, and the effect of the number of pistons (5, 6, and 7) is investigated. Over the manifolds of the pump, valve plate silencing grooves are regarded as Top Dead ...
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This study focuses on the flow and pressure fluctuations of a fixed displacement radial piston pump with a valve plate with silencing grooves, and the effect of the number of pistons (5, 6, and 7) is investigated. Over the manifolds of the pump, valve plate silencing grooves are regarded as Top Dead Center and Bottom Dead Center. The mathematical modeling is run in MATLAB Simulink. Analyzing the flow characteristics and volumetric efficiency of the pump with and without silencing groove valve plate configuration of the pump is done. The opening and closing area pattern of the kidney port is also analyzed. The percentage reduction of flow and pressure fluctuation with the silencing groove is 19% and 16.16%, respectively, for Z = 7, as compared to the model without silencing groove valve plate. The volumetric efficiency of the model with silencing groove valve plate is improved from 1% to 2% as compared to the model without silencing groove valve plate. The lower the flow and pressure fluctuation coefficients, the higher the flow rate and volumetric efficiency of the pump for the model with silencing groove valve plate.
Plasticity
S. Pirmohammad; S. Esmaeili-Marzdashti; A. Eyvazian
Abstract
In this article, crashworthiness performance and crushing behavior of tapered structures with four internal reinforcing plates under axial and oblique dynamic loadings have been investigated. These structures have a tapered form with five cross sections of square, hexagonal, octagonal, decagon and circular ...
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In this article, crashworthiness performance and crushing behavior of tapered structures with four internal reinforcing plates under axial and oblique dynamic loadings have been investigated. These structures have a tapered form with five cross sections of square, hexagonal, octagonal, decagon and circular shape. In the first step, finite element simulations performed in LS-DYNA were validated by comparing with experimental data. The code generated in LS-DYNA was then used to investigate energy absorption behavior of the tapered structures. Response surface methodology and historical data design technique were employed to optimize the cross section perimeter (tapered angle) of the tapered structures by considering two conflicting crashworthiness criteria including EA (energy absorption) and PCF (peak crushing force). The optimization results showed that the optimal tapered angle enhanced by increasing the number of cross section sides (or number of corners). Then, the optimized tapered structures with different cross-sections were compared with each other using a ranking method called TOPSIS to introduce the most efficient energy absorber. The decagonal structure was finally found to be the best energy absorber.
Internal Combustion Engine
A. Shaafi; M. J. Noroozi; V. Manshaei
Abstract
In this computational research, the separate and simultaneous impacts of diesel direct injection timing, fuel spraying cone angle, and hydrogen gas addition on combustion characteristics, output emissions, and performance in a single-cylinder direct injection diesel engine was studied. In order to conduct ...
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In this computational research, the separate and simultaneous impacts of diesel direct injection timing, fuel spraying cone angle, and hydrogen gas addition on combustion characteristics, output emissions, and performance in a single-cylinder direct injection diesel engine was studied. In order to conduct the simulations, valid and reliable models for combustion, break-up, and for turbulence was used. The effects of fifteen fuel injection strategies based on characteristics such as time of fuel spraying (-15, -10 CA BTDC, and TDC) and nozzle cone angle (105, 115, 125, 145, and 160 degrees) under neat diesel combustion and diesel-hydrogen combustion engine operations conditions were explored. The obtained results indicated that the addition of H2 due to significant heating value has increased indicated power and improved indicated specific energy consumption at the expense of NOx emissions but considerably decreased CO and soot emissions simultaneously. By advancing injection timing, maximum pressure peak point, maximum temperature peak point, and maximum heat release rate peak point have increased and caused lower indicated specific energy consumption. However, using a wide spray angle (e.g., 160 cone degrees), resulted in lower indicated power and higher indicated specific energy consumption due to more fuel could spray in regions with lower oxygen concentrations compared to baseline operation case.
Manufacturing Processes
Hasan Ghafourian Nosrati; Mahdi Gerdooei
Abstract
In recent years, most industries such as the aerospace, automotive, and others have been pushed to methods for reducing costs. One of these methods is the rubber pad forming (RPF) process, which has been given more attention as a low-cost method than conventional methods. In RPF, unlike conventional ...
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In recent years, most industries such as the aerospace, automotive, and others have been pushed to methods for reducing costs. One of these methods is the rubber pad forming (RPF) process, which has been given more attention as a low-cost method than conventional methods. In RPF, unlike conventional methods which mainly use metals as tools, one of the tools will be made of elastic pads. The RPF process has attracted the attention of many researchers around the world. Researchers from Iran started their work in this field around 2001 and subsequently published several remarkable articles. The first published Iranian study of the RPF process dates back to 2003, indicating that the use of flexible tools has a history of two decades in Iran. However, in the last decade, the number of published Iranian articles in the RPF process field and the introduction of new methods based on RPF and its simulation has increased. This review article aims to outline Iran's involvement in the RPF process, and it emphasizes that Iranian researchers predominantly contribute to the RPF process through simulation, experimental endeavors, and the introduction of innovative methods utilizing flexible tools.
Optimization
A. Haitao Zhang; B. Li Guan; C. Long Chang
Abstract
Rolling bearings are critical components of rotating machinery, and their health status directly affects the operational reliability of equipment. This paper proposes an optimized wavelet-SVM fault diagnosis method based on multi-source vibration signal fusion: Three-channel inputs are constructed by ...
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Rolling bearings are critical components of rotating machinery, and their health status directly affects the operational reliability of equipment. This paper proposes an optimized wavelet-SVM fault diagnosis method based on multi-source vibration signal fusion: Three-channel inputs are constructed by synchronously collecting vibration signals from the drive end and fan end, along with their differential signals; Wavelet packet decomposition is utilized to extract frequency-domain features such as unit node energy entropy and wavelet coefficient standard deviation, while dimensionless indicators independent of rotational speed (kurtosis factor/waveform factor/impulse factor) are introduced to enhance time-domain characterization; The fused features are input into an RBF-SVM classifier after dimensionality reduction via PCA (retaining 99% variance, reducing dimensions from 102 to 4). Experiments indicate that on the CWRU dataset, this method achieves 97.0% precision, 96.9% recall, and an F1-score of 96.9% (representing a 2.9% improvement over single-source input methods); Although there is a 2.4% absolute accuracy gap compared to deep learning solutions, it possesses significant edge advantages—memory usage is only 12KB and inference latency is 0.6ms—providing a high-precision, low-cost embedded solution for rotating machinery fault diagnosis
Forming
Mohammad Riahi; Mohamad Hoseinpour Gollo; Seiied Nader Ameli Kalkhoran
Abstract
Laser forming is a modern process which is mainly used for forming metals. Different Lasers are used in this regard that includes Nd: YAG and CO2. In this study, forming bi-layer sheets of Aluminum/Ceramic by Laser was investigated. Furthermore, effect of Uniform and Gaussian heat flux distribution in ...
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Laser forming is a modern process which is mainly used for forming metals. Different Lasers are used in this regard that includes Nd: YAG and CO2. In this study, forming bi-layer sheets of Aluminum/Ceramic by Laser was investigated. Furthermore, effect of Uniform and Gaussian heat flux distribution in different power, velocity, and beam diameters on bending angle was studied. FEM simulation indicated that, in the same conditions of analysis, Uniform heat flux distribution caused higher bending angle than Gaussian heat flux distribution. Moreover, the results showed that there was an optimum point at different speeds and laser beam diameters, at which the bending angle was maximum. In order to evaluating the numerical results, a set of experiments was conducted, which showed good agreement.
Fluid Mechanics
Gh. Payganeh; A. Hadidi; M. Hallaji; N. Garjasi
Abstract
Over the last ten years, robustness of schemes has raised an increasing interest among the CFD community. The objective of this article is to solve the quasi-one-dimensional compressible flow inside a “Shubin nozzle” and to investigate Bean-Warming and flux vector splitting methods for numerical ...
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Over the last ten years, robustness of schemes has raised an increasing interest among the CFD community. The objective of this article is to solve the quasi-one-dimensional compressible flow inside a “Shubin nozzle” and to investigate Bean-Warming and flux vector splitting methods for numerical solution of compressible flows. Two different conditions have been considered: first, there is a supersonic flow in the entry and a supersonic flow in the outlet, without any shock in the nozzle. Second, there is a supersonic flow in the inlet and a subsonic flow in the outlet of the nozzle and a shock occur inside the nozzle. The results show that the run time of the flux vector splitting scheme is more than the Bean-Warming scheme, and, the flux vector splitting scheme is more accurate than the Bean-Warming scheme. However the flux vector splitting scheme is more complicated.
Forming
Hashem Zamanian; Mehdi Bostan Shirin; Ahmad Assempour
Abstract
In this work, an inverse finite element formulation was modified for considering material anisotropy in obtaining blank shape and forming severity of deep drawn orthotropic parts. In this procedure, geometry of final part and thickness of initial blank sheet were known. After applying ideal forming formulations ...
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In this work, an inverse finite element formulation was modified for considering material anisotropy in obtaining blank shape and forming severity of deep drawn orthotropic parts. In this procedure, geometry of final part and thickness of initial blank sheet were known. After applying ideal forming formulations between material points of initial blank and final shape, an equation system was obtained in terms of unknown initial positions on the blank sheet. Initial positions of material points were obtained by solving this equation system. In this algorithm, the Hill's anisotropic plasticity and associated plastic flow rule were used. Strain distribution on the final part was obtained by comparing the initial blank and final part. The method was applied for the simulation of drawing an orthotropic blank to a rectangular cup. Accuracy of the presented method was evaluated by comparing the results with numerical forward method and experiment results.
Optimization
M. Rahimi; M. Khalafi-Salout
Abstract
Heat transfer from the internal surfaces of a vertical pipe to the adjacent air gives rise to the air flow establishment within the pipe. With the aim of optimizing the convective air flow rate in a vertical pipe, the details of the flow and thermal fields were investigated in the present study. Conservation ...
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Heat transfer from the internal surfaces of a vertical pipe to the adjacent air gives rise to the air flow establishment within the pipe. With the aim of optimizing the convective air flow rate in a vertical pipe, the details of the flow and thermal fields were investigated in the present study. Conservation equations of mass, momentum, and energy were solved numerically using simple implicit forward-marching finite difference scheme for a two-dimensional axis-symmetric flow. In order to evaluate and optimize the air flow rate passing through the pipe, the position and intensity of the wall heat flux were altered when the total employed heat transfer rate was constant. Based on the results of the numerical analysis, relatively more air flow rate was achieved when more intensified heat flux was employed at the lowest part of the vertical pipe. This finding was then validated using a simple experimental setup. The results of the present study could be useful in the design and application of buoyancy-assisted natural ventilation systems.
Turbulance
S. F. Ahmed; M. S. A. Sarker Sarker
Abstract
The energy equation for turbulent flow of fiber suspensions was derived in terms of second order correlation tensors. Fiber motion of turbulent energy including the correlation between pressure fluctuations and velocity fluctuations was discussed at two points of flow field, at which the correlation ...
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The energy equation for turbulent flow of fiber suspensions was derived in terms of second order correlation tensors. Fiber motion of turbulent energy including the correlation between pressure fluctuations and velocity fluctuations was discussed at two points of flow field, at which the correlation tensors were the functions of space coordinates, distance between two points, and time.
Automation
Pardeep Rohilla; Vineet Kumar; Feras Al-Hakkak
Abstract
Inherent nonlinearities like, deadband, stiction and hysteresis in control valves degenerate plant performance. Valve stiction standouts as a more widely recognized reason for poor execution in control loops. Measurement of valve stiction is essential to maintain scheduling. For industrial scenarios, ...
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Inherent nonlinearities like, deadband, stiction and hysteresis in control valves degenerate plant performance. Valve stiction standouts as a more widely recognized reason for poor execution in control loops. Measurement of valve stiction is essential to maintain scheduling. For industrial scenarios, loss of execution due to nonlinearity in control valves is an imperative issue that should be tackled. Thus, an intelligent technique is required for automated execution, observation and enhancement. The paper shows the creative utilization of an intelligent controller for nonlinearity diagnosis in control valves. This is a Fuzzy Gain Scheduling (FGS) PID smart controller that tunes its gain parameters in real time to manage a control valve’s inherent nonlinearity. The viability of the FGS PID controller is experimentally verified in a laboratory scale plant. An execution comparison between FGS PID and classical PID controllers are undertaken for their set point following and disturbance rejection at different operating points. Experimental results show that the FGS PID controller outperforms the classical PID controller for all explored cases effectively managing stiction based oscillation in the controller output.
Computational Fluid Dynamics (CFD)
Vikram A. Kolhe; Suyash Y. Pawar; Vishal D. Chaudhari; Ravindra L. Edlabadkar; Kailas V. Chandratre
Abstract
Measuring flow rate precisely in laminar flow has been a difficult task, especially when utilizing a Coriolis mass flow meter (CMFM) for low flow rate measurements. The meter often under-reads the mass flow rate, making it less useful in these conditions. The dominant factor affecting the CMFM's ...
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Measuring flow rate precisely in laminar flow has been a difficult task, especially when utilizing a Coriolis mass flow meter (CMFM) for low flow rate measurements. The meter often under-reads the mass flow rate, making it less useful in these conditions. The dominant factor affecting the CMFM's performance in laminar regions is secondary flow, which overshadows the generated Coriolis force, leading to an under-reading of the flow rate. Previous studies have indicated that tube curvature is the most significant parameter affecting secondary flow generation and the overall performance of the meter. An omega-shaped tube configuration featuring a continuous curvature has been identified as the optimal shape for maximizing the performance of a CMFM device in laminar flow. The purpose of the investigation is to study and compare the efficiency of various Omega tube designs that have undergone slight geometric alterations. Four different configurations were evaluated for maximum time lag by vibrating at their respective natural frequencies and keeping the sensor position along the centerline of the tube configuration.
Welding
Saadat Ali Rizvi; S. P. Tewari
Abstract
This study investigated the optimization of three welding parameters (wire feed speed, arc voltage, and shielding gas flow rate) for SS 304H by using Taguchi based Grey relational analysis. In this research work, pure argon was used as shielding gas. Numbers of trials were performed as per ...
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This study investigated the optimization of three welding parameters (wire feed speed, arc voltage, and shielding gas flow rate) for SS 304H by using Taguchi based Grey relational analysis. In this research work, pure argon was used as shielding gas. Numbers of trials were performed as per L16 (4xx3) orthogonal array design and the mechanical quality such ultimate tensile strength, microhardness, Toughness, and microstructure of SS304H optimized by Grey-based Taguchi analysis and result shows that the optimal parameters combination were as A4B4C3 i.e. flow rate at 23L/min, voltage at 25 V and welding speed at 350IPM and it was observed that wire feed speed had the most significant effect followed by voltage and gas flow rate. An optimal combined parameter of the welding operation was obtained via Grey relational analysis. By analyzing Grey relational grade matrix, the degree of influence for each controllable process factor onto individual quality targets can be found.
Forming
A. H. Rabiee; E. Sherkatghanad; A. Zeinolabedin Beygi; H. Moslemi Naeini; L. Lang
Abstract
In this paper, by considering the processing parameters, including blank holder force, blank holder gap, and cavity pressure as the most important input factors in the hydroforming process, an experimental design is performed, and an adaptive neural-fuzzy inference system (ANFIS) is applied to model ...
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In this paper, by considering the processing parameters, including blank holder force, blank holder gap, and cavity pressure as the most important input factors in the hydroforming process, an experimental design is performed, and an adaptive neural-fuzzy inference system (ANFIS) is applied to model and predict the behavior of aluminum thinning rate (upper layer and lower layer), the height of wrinkles and achieved depths that are extracted in hydroforming process. Also, the optimal constraints of the network structure are obtained by the gray wolf optimization algorithm. Accordingly, the results of experimental tests are utilized for training and testing of the ANFIS. The accurateness of the attained network is examined using graphs and also based on the statistical criteria of root mean square error, mean absolute error, and correlation coefficient. The results show that the attained model is very effective in approximating the aluminum thinning rate (upper layer and lower layer), the height of wrinkles, and achieved depth in the hydroforming process. Finally, the results also show that the root means of the square error of aluminum thinning rate (upper layer and lower layer), the height of wrinkles, and achieved depth of the test section are 1.67, 2.25, 0.05, and 2.67, respectively. It is also observed that the correlation coefficient for the test data is very close to 1, which demonstrates the high precision of the ANFIS in predicting the outputs of the hydroforming procedure.
Energy Science and Technology
I. Vinothkanna; K. Subramani; A. Devaraj
Abstract
The petroleum product has seen a drastic demand in the recent past. Biofuels are the only solution to overcome this power crisis. In the view of sustainable energy development, biodiesel and its additives have become the best options for fossil fuel-based engines. In this work, a biodiesel mix was used ...
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The petroleum product has seen a drastic demand in the recent past. Biofuels are the only solution to overcome this power crisis. In the view of sustainable energy development, biodiesel and its additives have become the best options for fossil fuel-based engines. In this work, a biodiesel mix was used to show the possible utilization of different biofuels. An experimental investigation was carried out on a direct-injection constant-speed (Rated speed- 1500 rpm) diesel engine at different injection pressures of 180, 220 and 260 bar with natural aspiration and supercharging modes. The blends of Biodiesel (used cooking oil, with a mix of algae) and diesel fuels are the selected fuel to investigate. At lower injection pressures, brake specific fuel consumption of the engine was low and further lowered with supercharging operation. With the reduction of injection pressures, brake thermal efficiency values are improved, and the same was observed with supercharging. With the rise in injection pressures, NOx emissions increased due to rise in temperature, and unburnt hydrocarbon emissions were slightly increased. The algae biodiesel was used as an additive to increase the stability of biodiesel. The overall observation indicates that a moderate injection pressure of 220 bar is advisable.
Manufacturing Processes
Haneen Lateef; Saad Mahmood Ali
Abstract
The objective of this study is to examine how the input parameters of wet-EDM, near-dry (ND-EDM), and NDPM-EDM affect the output performances of the newly fabricated metal matrix composites (MMCs) of aluminum Al-7075/MSGNP nanocomposites produced by the stir-casting. Air, Ar, mix (Ar+N2), and Ferron ...
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The objective of this study is to examine how the input parameters of wet-EDM, near-dry (ND-EDM), and NDPM-EDM affect the output performances of the newly fabricated metal matrix composites (MMCs) of aluminum Al-7075/MSGNP nanocomposites produced by the stir-casting. Air, Ar, mix (Ar+N2), and Ferron gases were included in the current study, which used vegetable oil as a dielectric medium. Additionally, Kaolinite Nano powders were employed as an additive in ND-EDM studies. The data obtained indicate that the greatest MRR attained in the ND-EDM process was 29.425 mm3/min when vegetable oil and Freon gas were used. In the NDPM-EDM, the highest achieved MRR obtained using the Freon gas reached 15.468 (used 800 µsec, 5% Al2SiO2(OH)4). The obtained result is higher than the highest value obtained when using vegetable oil alone by 209.37%. The lowest achieved EWR obtained using the Freon gas reached 0.003 with the vegetable oil + 5% and 10% Al2SiO2(OH)4). The lowest achieved SR for all the implemented experiments, was obtained with used the Freon additive gas to dielectric, reached 4.797 µm (used 5% Al2SiO2(OH)4). The SR value obtained is 19.88% lower than the minimum value achieved when using only vegetable oil. The SEM study showed that the average thickness of the recast white layer was significantly reduced when using the ND-EDM approaches compared to the standard wet-EDM method. The decrease percentages for introducing air, Ar, mix (Ar-N2), and Freon gases into the vegetable oil dielectrics for ND-EDM were 108.17%, 165.51%, 630.26%, and (∞).
Nonlinear Solution
Adnan Maqsood; Muhammad Kamran Khan Tareen; Rizwan Riaz; Laurent Dala
Abstract
The paper discusses the effect of compressor characteristic on surge phenomena in axial flow compressors. Specifically, the effect of nonlinearities on the compressor dynamics is analyzed. For this purpose, generalized multiple time scales method is used to parameterize equations in amplitude and frequency ...
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The paper discusses the effect of compressor characteristic on surge phenomena in axial flow compressors. Specifically, the effect of nonlinearities on the compressor dynamics is analyzed. For this purpose, generalized multiple time scales method is used to parameterize equations in amplitude and frequency explicitly. The pure surge case of the famous Moore-Greitzer model is used as the basis of the study. The compressor characteristic used in the Moore-Greitzer model is generalized to evaluate the effect of the parameters involved. Subsequently, bifurcation theory is used to study the effect of nonlinear dynamics on surge behavior. It has been found that the system exhibits supercritical Hopf bifurcation under specific conditions in which surge manifests as limit cycle oscillations. Key parameters have been identified in the analytical solution which govern the nonlinear dynamic behavior and are responsible for the existence of limit cycle oscillations. Numerical simulations of the Moore-Greitzer model are carried out and found to be in good agreement with the analytical solution
Heat and Mass Transfer
B. Malleswari; T. Poornima; P. Sreenivasulu; N. Bhaskar Reddy
Abstract
This study emphasizes the upshots of non-linear radiation and electrical resistance heating on a three dimensional Jeffrey dissipating nanoflow in view of convective surface conditions. The initial set of nonlinear dimensional boundary layer equations are transformed into a system of ordinary differential ...
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This study emphasizes the upshots of non-linear radiation and electrical resistance heating on a three dimensional Jeffrey dissipating nanoflow in view of convective surface conditions. The initial set of nonlinear dimensional boundary layer equations are transformed into a system of ordinary differential equations with suitable similarity variables and then solved by shooting method using Mathematica software. For various representative quantities, the behavior of the momentum, energy and species diffusion along with engineering quantities near the surface are figured for different estimations of the fluid properties. The examination of the present outcomes has been made with the existing work which is in good agreement. This study helps in understanding that the heat transfer rate is predominant in the non-linear radiation compared to linear radiation. Jeffrey fluid model has the capacity of describing the stress relaxation property, that usually viscous fluid lags and this is exhibited clearly in the study. Shear stress descends as the fluid pertinent parameter ascends.
Forming
S. Izadpanah; S. H. Ghaderi; M. Gerdooei
Abstract
This paper investigates the earing phenomenon in deep drawing of AA3105 aluminum alloy, experimentally and numerically. Earing defect is mainly attributed to the plastic anisotropy of sheet metal. In order to control such defect, predicting the evolution of ears in sheet metal forming analyses becomes ...
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This paper investigates the earing phenomenon in deep drawing of AA3105 aluminum alloy, experimentally and numerically. Earing defect is mainly attributed to the plastic anisotropy of sheet metal. In order to control such defect, predicting the evolution of ears in sheet metal forming analyses becomes indispensable. In this regard, the present study implements the advanced yield criterion BBC2003. Based on this yield function and the associated flow rule of plasticity, the constitutive model is derived. Accordingly, a user material VUMAT subroutine is developed and adopted in the commercial finite element software ABAQUS/Explicit. Several plane stress loading problems are designed, through which, the accuracy of the developed subroutine is verified. In addition, cylindrical cups of AA3105 aluminum alloy are fabricated using a deep drawing die. The earing defect was clearly observed on the recovered parts. Using the experimentally obtained constants of BBC2003 yield criterion for this alloy in VUMAT, deep drawing of the cylindrical cups was simulated. The results demonstrate that the earing profile can successfully be predicted using BBC2003 yield function.
Fluid Mechanics
Abolfazl Khalkhali*; Hamed Safikhani
Abstract
In this paper, lift and drag coefficients were numerically investigated using NUMECA software in a set of 4-digit NACA airfoils. Two metamodels based on the evolved group method of data handling (GMDH) type neural networks were then obtained for modeling both lift coefficient (CL) and drag coefficient ...
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In this paper, lift and drag coefficients were numerically investigated using NUMECA software in a set of 4-digit NACA airfoils. Two metamodels based on the evolved group method of data handling (GMDH) type neural networks were then obtained for modeling both lift coefficient (CL) and drag coefficient (CD) with respect to the geometrical design parameters. After using such obtained polynomial neural networks, modified non-dominated sorting genetic algorithm (NSGAII) was used for Pareto based optimization of 4-digit NACA airfoils considering two conflicting objectives such as (CL) and (CD). Further evaluations of the design points in the obtained Pareto fronts using the NUMECA software showed the effectiveness of such an approach. Moreover, it was shown that some interesting and important relationships as the useful optimal design principles involved in the performance of the airfoils can be discovered by the Pareto-based multi-objective optimization of the obtained polynomial meta-models. Such important optimal principles would not have been obtained without using the approach presented in this paper.
Control
Seyed Vahab Shojaedini; Armin Parsiannejad
Abstract
This paper describes a new method for harvesting maximum electrical energy in wind farms. In proposing technique, the stochastic process principles are applied for detecting fault measurements of sensors. On the other hand, the wind farm is modeled by using fuzzy concept. Thereby the turbines are controlled ...
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This paper describes a new method for harvesting maximum electrical energy in wind farms. In proposing technique, the stochastic process principles are applied for detecting fault measurements of sensors. On the other hand, the wind farm is modeled by using fuzzy concept. Thereby the turbines are controlled against continuous changes in speed, direction and eddy currents of the blowing wind. To evaluate the performance of the proposed method three practical conditions of wind blowing are simulated. In the first scenario, the normal wind is simulated with low turbulence and slow changes. The second scenario belongs to high turbulence winds with sudden shifts in their parameters, and finally in the most complex scenario, several eddy currents are considered in blowing winds too. The obtained results show that the proposed method provides greater and more uniform harvested power compared to alternative methods. Furthermore, its superiority against other techniques has increased in parallel with the scenario become more complicated.
Robotics
A. Rahmani Hanzaki; E. Yoosefi
Abstract
This paper shows the coordinates influence on singularity of a three degree-of-freedom structure, namely, three-Universal-Prismatic-Spherical (3-UPS) parallel manipulator. Rotational coordinates, which are chosen to define the orientation of the platform, affect the singularity of the manipulator. Euler ...
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This paper shows the coordinates influence on singularity of a three degree-of-freedom structure, namely, three-Universal-Prismatic-Spherical (3-UPS) parallel manipulator. Rotational coordinates, which are chosen to define the orientation of the platform, affect the singularity of the manipulator. Euler parameters, which don't have any inherent geometrical singularity are utilized, however they are dependent coordinates. This paper shows the advantage of Euler parameters rather than Euler angles as the rotational coordinates for the manipulator. Additionally, the real loci of singularity for the manipulator due to its structure are predicted.
Vibration
S. J. Zakavi; B. Shiralivand; M. Nourbakhsh
Abstract
In this paper, the ratcheting behavior of carbon steel (ASTM A106B) and stainless steel (304L) elbows is studied under steady internal pressure and in-plane external moments at frequencies typical of seismic excitations. The finite element analysis with the nonlinear isotropic/kinematic (combined) hardening ...
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In this paper, the ratcheting behavior of carbon steel (ASTM A106B) and stainless steel (304L) elbows is studied under steady internal pressure and in-plane external moments at frequencies typical of seismic excitations. The finite element analysis with the nonlinear isotropic/kinematic (combined) hardening model is used to evaluate ratcheting behavior of the elbows. Material parameters are obtained from several stabilized cycles of specimens that are subjected to symmetric strain cycles. The rate of ratcheting depends significantly on the magnitudes of the internal pressure, dynamic bending moment and material constants for combined hardening model. The results show that the maximum ratcheting occurs in the hoop direction at the crown. Also, the results show that initially, the calculated rate of ratcheting is large and then decreases with the increasing cycles. Also, the results obtained by using the combined hardening model gives acceptable adaptation in comparison with the other hardening models (AF and Chaboche hardening models); however, this model gives overestimated values comparing with the experimental data.
Vibration
N. Mellel; M. Ouali; M. Dougdag; B. Mohammedi
Abstract
This paper presents an extended cross modal strain energy change method to estimate the severity of damage associated with limited modal data in beam-like structures. This method takes in account the correlation between the analytical modal data and the measured incomplete modal data. A procedure ...
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This paper presents an extended cross modal strain energy change method to estimate the severity of damage associated with limited modal data in beam-like structures. This method takes in account the correlation between the analytical modal data and the measured incomplete modal data. A procedure was proposed and the analytical elemental stiffness of the damaged element after it is localized is included in quantification of the measured single damage extent. A three-dimensional numerical beam model with different damage cases is used to simulate the CMSE method application and to getting the bending displacements of the damaged element. An experimental modal analysis (EMA) on a cantilever beam with and without crack was carried out to evaluate the effectiveness of the extended CMSE method. The severity magnitude of the damage was predicted within an acceptable error range through the using validation process. Results reveal that the proposed damage estimation method successfully evaluates single damage severity in beam like structure and can be useful in maintenance technology and structural health monitoring system.
Nonlinear Solution
M. Matinfar; M. Ghasemi
Abstract
Variational Iteration method using He's polynomials can be used to construct solitary solution and compacton-like solution for nonlinear dispersive equatioons. The chosen initial solution can be determined in compacton-like form or in solitary form with some compacton-like or solitary forms with ...
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Variational Iteration method using He's polynomials can be used to construct solitary solution and compacton-like solution for nonlinear dispersive equatioons. The chosen initial solution can be determined in compacton-like form or in solitary form with some compacton-like or solitary forms with some unknown parameters, which can be determined in the solution procedure. The compacton-like solution and solitary solution can be converted into each other.
