The application of imperialist competitive algorithm for optimization of deposition rate in submerged arc welding process using TiO2 nano particle

Mohammad Reza Ghaderi,Masood Aghakhani,Amir Hossein Eslampanah,Kianoosh Ghaderi 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.1

We used a novel optimization algorithm based on the imperialist competitive algorithm (ICA) to optimize the deposition rate in thesubmerged arc welding (SAW) process. This algorithm offers some advantages such as simplicity, accuracy and time saving. Experimentswere conducted based on a five factor, five level rotatable central composite design (RCCD) to collect welding data for depositionrate as a function of welding current, arc voltage, contact tip to plate distance, welding speed and thickness of TiO2 nanoparticles coatedon the plates of mild steel. Furthermore, regression equation for deposition rate was obtained using least squares method. The regressionequation as the cost function was optimized using ICA. Ultimately, the levels of input variables to achieve maximum deposition ratewere obtained using ICA. Computational results indicate that the proposed algorithm is quite effective and powerful in optimizing thecost function.

Power System and Drive-Train for Omni-Directional Autonomous Mobile Robots with Multiple Energy Storage Units

Ghaderi, Ahmad,Nassiraei, Amir A.F,Sanada, Atsushi,Ishii, Kazuo,Godler, Ivan The Korean Institute of Power Electronics 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.4

In this paper power system and drive-train for omni-directional autonomous mobile robots with multiple energy storage units are presented. Because in proposed system, which is implemented in soccer robots, the ability of power flow control from of multiple separated energy storage units and speed control for each motor are combined, these robots can be derived by more than one power source. This capability, allow robot to diversify its energy source by employing hybrid power sources. In this research Lithium ion polymer batteries have been used for main and auxiliary energy storage units because of their high power and energy densities. And to protect them against deep discharge, over current and short circuit, a protection circuit was designed. The other parts of our robot power system are DC-DC converters and kicker circuit. The simulation and experimental results show proposed scheme and extracted equations are valid and energy management and speed control can be achieved properly using this method. The filed experiments show robot mobility functions to perform the requested motion is enough and it has a high maneuverability in the field.

A Novel Seamless Direct Torque Control for Electric Drive Vehicles

Ghaderi, Ahmad,Umeno, Takaji,Amano, Yasushi,Masaru, Sugai The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.4

Electric drive vehicles (EDV) have received much attention recently because of their environmental and energy benefits. In an EDV, the motor drive system directly influences the performance of the propulsion system. However, the available DC voltage is limited, which limits the maximum speed of the motors. At high speeds, the inverter voltage increases if the square wave (SW) voltage (six-step operation) is used. Although conventional direct torque control (DTC) has several advantages, it cannot work in the six-step mode required in high-speed applications. In this paper, a single-mode seamless DTC for AC motors is proposed. In this scheme, the trajectory of the reference flux changes continuously between circular and hexagonal paths. Therefore, the armature voltage changes smoothly from a high-frequency switching pattern to a square wave pattern without torque discontinuity. In addition, because multi-mode controllers are not used, implementation is more straightforward. Simulation results show the voltage pattern changes smoothly when the motor speed changes, and consequently, torque control without torque discontinuity is possible in the field weakening area even with a six-step voltage pattern.

NEW ORBITAL PARAMETERS AND RADIAL VELOCITY CURVE ANALYSIS OF SPECTROSCOPIC BINARY STARS

Ghaderi, Kamal,Pirkhedri, Ali,Rostami, Touba,Khodamoradi, Salem,Fatahi, Hedayat The Korean Astronomical Society 2012 Journal of The Korean Astronomical Society Vol.45 No.1

We use a Probabilistic Neural Network (PNN) technique to derive the orbital parameters of spectroscopic binary stars. Using measured radial velocity data of five double-lined spectroscopic binary systems (i.e., EQ Tau, V376 And, V776 Cas, V2377 Oph and EE Cet), we find the corresponding orbital and spectroscopic elements. Our numerical results are in good agreement with those obtained by other groups via more traditional methods.

A Novel Sensorless Low Speed Vector Control for Synchronous Reluctance Motors Using a Block Pulse Function-Based Parameter Identification

Ghaderi Ahmad,Hanamoto Tsuyoshi,Tsuji Teruo 전력전자학회 2006 JOURNAL OF POWER ELECTRONICS Vol.6 No.3

Recently, speed sensorless vector control for synchronous reluctance motors (SYRMs) has deserved attention because of its advantages. Although rotor angle calculation using flux estimation is a straightforward approach, the DC offset can cause an increasing pure integrator error in this estimator. In addition, this method is affected by parameter fluctuation. In this paper, to control the motor at the low speed region, a modified programmable cascaded low pass filter (MPCPLF) with sensorless online parameter identification based on a block pulse function is proposed. The use of the MPCLPF is suggested because in programmable cascade low pass filters (PCLPF), which previously have been applied to induction motors, the drift increases vastly when motor speed decreases. Parameter identification is also used because it does not depend on estimation accuracy and can solve parameter fluctuation effects. Thus, sensorless speed control in the low speed region is possible. The experimental system includes a PC-based control with real time Linux and an ALTERA Complex Programmable Logic Device (CPLD), to acquire data from sensors and to send commands to the system. The experimental results show the proposed method performs well, speed and angle estimation are correct. Also, parameter identification and sensorless vector control are achieved at low speed, as well as, as at high speed.

High-Impedance Fault Detection in the Distribution Network Using the Time-Frequency-Based Algorithm

Ghaderi, Amin,Mohammadpour, Hossein Ali,Ginn, Herbert L.,Yong-June Shin Institute of Electrical and Electronics Engineers 2015 IEEE Transactions on Power Delivery Vol. No.

<P>A new high-impedance fault (HIF) detection method using time-frequency analysis for feature extraction is proposed. A pattern classifier is trained whose feature set consists of current waveform energy and normalized joint time-frequency moments. The proposed method shows high efficacy in all of the detection criteria defined in this paper. The method is verified using real-world data, acquired from HIF tests on three different materials (concrete, grass, and tree branch) and under two different conditions (wet and dry). Several nonfault events, which often confuse HIF detection systems, were simulated, such as capacitor switching, transformer inrush current, nonlinear loads, and power-electronics sources. A new set of criteria for fault detection is proposed. Using these criteria, the proposed method is evaluated and its performance is compared with the existing methods. These criteria are accuracy, dependability, security, safety, sensibility, cost, objectivity, completeness, and speed. The proposed method is compared with the existing methods, and it is shown to be more reliable and efficient than its existing counterparts. The effect of choice of the pattern classifier on method efficacy is also investigated.</P>

Response to Drought Stress of Two Strawberry Cultivars (cv. Kurdistan and Selva)

Nasser Ghaderi,Adell Siosemardeh 한국원예학회 2011 Horticulture, Environment, and Biotechnology Vol.52 No.1

In order to evaluate the effect of different levels of drought stress on some physiological parameters in strawberry, one experiment with potted strawberry cultivars ‘Kurdistan’ and ‘Selva’ was conducted in summer 2008. The experiment was performed with four drought stress treatments [control (75% of field capacity), S1: mild drought stress (50% of field capacity), S2: severe drought stress (25% of field capacity) and R: one day after rewatering]. Physiological parameters such as: leaf relative water content (RWC), membrane stability index (MSI), net CO2 assimilation rate (A), stomatal conductance (gs), transpiration (E), water use efficiency (A/gs), chlorophyll, proline and soluble carbohydrate contents were measured in leaves of strawberry subjected to different drought stress conditions as well as one day after rewatering. The results showed that RWC, MSI, A, gs, E, and chlorophyll of two cultivars decreased as soil water content was reduced. A/gs was highest under mild water stress for both cultivars. ‘Kurdistan’ had lower A, gs and E than ‘Selva’. RWC, MSI and A/gs of ‘Kurdistan’ were higher than ‘Selva’. Recovery of these parameters was faster for ‘Kurdistan’ than ‘Selva’. Chlorophyll contents of ‘Kurdistan’ was higher than ‘Selva’. Chlorophyll recovery didn’t occur one day after rewatering. Amount of proline and soluble carbohydrates increased under severe drought stress. ‘Kurdistan’ had higher proline content compared to ‘Selva’ under severe drought stress. Amount of proline and soluble carbohydrates were reduced in both the cultivars one day after rewatering. This study revealed that moderate drought stress affects gas exchange while severe drought stress affects chlorophyll, proline and soluble carbohydrates levels.

Codification strategies for achieving spatial justice in Iran

Mostafa Ghaderi Hajat,Mohammad Reza Hfeznia 대한공간정보학회 2020 Spatial Information Research Vol.28 No.3

Spatial injustice is an important feature of spatial organization in Iran, which is formulated on a core-periphery structure from the local to national scale. The current research with use descriptive-analytic method intends to codify solutions to access spatial justice in Iran. The results showed that spatial injustice in Iran relates to its natural geography and unequal distribution of natural resources (inherent characteristics), the human geography and spatial structure of the nation, centralism in political system, methods of policy-making, national development planning, regional and global geopolitical environment, inequality in the distribution of political power, wealth and opportunity resources. According to the research, to access spatial justice, the following strategies have been suggested: optimal spatial distribution of wealth flow as a developmental prerequisite namely management of money flow in the country, allocation of a specific portion of provincial budgets for balanced development in order to achieve regional balance, strengthening of local potential to increase the efficiency of achieving balanced development, attention to the systemic thinking about spatial justice and planning at the local, regional and national levels, revision of the principles of the Constitution related to the centralization for spatial distribution of executive and political power in the country.

The length of plastic hinge area in the flanged reinforced concrete shear walls subjected to earthquake ground motions

Farzad Ghaderi Bafti,Alireza Mortezaei,Ali Kheyroddin 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.6

Past earthquakes have shown that appropriately designed and detailed buildings with shear walls have great performance such a way that a considerable portion of inelastic energy dissipation occurs in these structural elements. A plastic hinge is fundamentally an energy diminishing means which decrease seismic input energy through the inelastic deformation. Plastic hinge development in a RC shear wall in the areas which have plastic behavior depends on the ground motions characteristics as well as shear wall details. One of the most generally used forms of structural walls is flanged RC wall. Because of the flanges, these types of shear walls have large in-plane and out-of-plane stiffness and develop high shear stresses. Hence, the purpose of this paper is to evaluate the main characteristics of these structural components and provide a more comprehensive expression of plastic hinge length in the application of performance-based seismic design method and promote the development of seismic design codes for shear walls. In this regard, the effects of axial load level, wall height, wall web and flange length, as well as various features of earthquakes, are examined numerically by finite element methods and the outcomes are compared with consistent experimental data. Based on the results, a new expression is developed which can be utilized to determine the length of plastic hinge area in the flanged RC shear walls.

A Novel Seamless Direct Torque Control for Electric Drive Vehicles

Ahmad Ghaderi,Takaji Umeno,Yasushi Amano,Sugai Masaru 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.4

Electric drive vehicles (EDV) have received much attention recently because of their environmental and energy benefits. In an EDV, the motor drive system directly influences the performance of the propulsion system. However, the available DC voltage is limited, which limits the maximum speed of the motors. At high speeds, the inverter voltage increases if the square wave (SW) voltage (six-step operation) is used. Although conventional direct torque control (DTC) has several advantages, it cannot work in the six-step mode required in high-speed applications. In this paper, a single-mode seamless DTC for AC motors is proposed. In this scheme, the trajectory of the reference flux changes continuously between circular and hexagonal paths. Therefore, the armature voltage changes smoothly from a high-frequency switching pattern to a square wave pattern without torque discontinuity. In addition, because multi-mode controllers are not used, implementation is more straightforward. Simulation results show the voltage pattern changes smoothly when the motor speed changes, and consequently, torque control without torque discontinuity is possible in the field weakening area even with a six-step voltage pattern.