Showing papers by "Iran University of Science and Technology published in 2013"
TL;DR: The performance of the CS algorithm is further compared with various algorithms representative of the state of the art in the area and the optimal solutions obtained are mostly far better than the best solutions obtained by the existing methods.
Abstract: In this study, a new metaheuristic optimization algorithm, called cuckoo search (CS), is introduced for solving structural optimization tasks. The new CS algorithm in combination with Levy flights is first verified using a benchmark nonlinear constrained optimization problem. For the validation against structural engineering optimization problems, CS is subsequently applied to 13 design problems reported in the specialized literature. The performance of the CS algorithm is further compared with various algorithms representative of the state of the art in the area. The optimal solutions obtained by CS are mostly far better than the best solutions obtained by the existing methods. The unique search features used in CS and the implications for future research are finally discussed in detail.
1,701 citations
TL;DR: This study introduces chaos into FA so as to increase its global search mobility for robust global optimization and shows that some chaotic FAs can clearly outperform the standard FA.
703 citations
TL;DR: The modeling, control design, and stability analysis of parallel-connected three-phase VSIs are derived and a hierarchical control scheme for the paralleled VSI system control architecture is developed.
Abstract: Power-electronics-based microgrids (MGs) consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of parallel-connected three-phase VSIs are derived. The proposed voltage and current inner control loops and the mathematical models of the VSIs are based on the stationary reference frame. A hierarchical control scheme for the paralleled VSI system is developed comprising two levels. The primary control includes the droop method and the virtual impedance loops, in order to share active and reactive powers. The secondary control restores the frequency and amplitude deviations produced by the primary control. Also, a synchronization algorithm is presented in order to connect the MG to the grid. Experimental results are provided to validate the performance and robustness of the parallel VSI system control architecture.
610 citations
TL;DR: Dolphin echolocation takes advantages of these rules and outperforms many existing optimization methods, while it has few parameters to be set, and this approach leads to excellent results with low computational efforts.
427 citations
TL;DR: The proposed multi-objective robust stochastic programming approach for disaster relief logistics under uncertainty can help in making decisions on both facility location and resource allocation in cases of disaster relief efforts.
Abstract: Humanitarian relief logistics is one of the most important elements of a relief operation in disaster management. The present work develops a multi-objective robust stochastic programming approach for disaster relief logistics under uncertainty. In our approach, not only demands but also supplies and the cost of procurement and transportation are considered as the uncertain parameters. Furthermore, the model considers uncertainty for the locations where those demands might arise and the possibility that some of the pre-positioned supplies in the relief distribution center or supplier might be partially destroyed by the disaster. Our multi-objective model attempts to minimize the sum of the expected value and the variance of the total cost of the relief chain while penalizing the solution's infeasibility due to parameter uncertainty; at the same time the model aims to maximize the affected areas' satisfaction levels through minimizing the sum of the maximum shortages in the affected areas. Considering the global evaluation of two objectives, a compromise programming model is formulated and solved to obtain a non-dominating compromise solution. We present a case study of our robust stochastic optimization approach for disaster planning for earthquake scenarios in a region of Iran. Our findings show that the proposed model can help in making decisions on both facility location and resource allocation in cases of disaster relief efforts.
352 citations
TL;DR: In this article, the potential of the prepared nanofiber membrane for adsorption of nickel (Ni), cadmium (Cd), lead (Pb) and copper (Cu) from aqueous solution was investigated.
330 citations
TL;DR: A stationary-frame control method for voltage unbalance compensation in an islanded microgrid is proposed, based on the proper control of DGs interface converters, which demonstrates the effectiveness of the proposed method in the compensation of voltage un balance.
Abstract: Recently, there has been an increasing interest in using distributed generators (DGs) not only to inject power into the grid but also to enhance the power quality. In this paper, a stationary-frame control method for voltage unbalance compensation in an islanded microgrid is proposed. This method is based on the proper control of DGs interface converters. The DGs are properly controlled to autonomously compensate for voltage unbalance while sharing the compensation effort and also active and reactive powers. The control system of the DGs mainly consists of active and reactive power droop controllers, a virtual impedance loop, voltage and current controllers, and an unbalance compensator. The design approach of the control system is discussed in detail, and simulation and experimental results are presented. The results demonstrate the effectiveness of the proposed method in the compensation of voltage unbalance.
319 citations
TL;DR: In this article, a wide variety of 2-amino-4H-chromene derivatives with diverse substituents on the 4Hchromene ring were efficiently prepared via one-pot, three-component reaction of an aromatic aldehyde, malononitrile (or ethyl cyanoacetate), and diverse enolizable C-H activated acidic compounds in the presence of low loading of potassium phthalimide-N-oxyl (POPINO), as a new organocatalyst, in aqueous media.
238 citations
TL;DR: The Au-SH-SiO₂@Cu-MOF showed a very efficient electrocatalytic activity for the oxidation of L-cysteine in 0.1 M phosphate buffer solution (pH 5.0).
233 citations
TL;DR: In this article, experiments were conducted to evaluate the parameters that affect the particle breakage of calcareous sands, including confining pressure, relative density, axial strain, drainage conditions and grain size distribution.
226 citations
TL;DR: In this paper, the authors investigated the biosorption of cadmium and nickel onto grapefruit peel from aqueous solution using batch technique and fitted the equilibrium adsorption data to Langmuir and Freundlich isotherm models and evaluated the model parameters.
Abstract: The biosorption of cadmium and nickel onto grapefruit peel from aqueous solution has been investigated using batch technique. Experiments are carried out as a function of solution pH, biosorbent dosage, contact time and temperature. The equilibrium adsorption data are fitted to Langmuir and Freundlich isotherm models and the model parameters are evaluated. The Freundlich model fits the equilibrium data better than the Langmuir model. The maximum uptakes of Cd(II) and Ni(II) by grapefruit peel are found to be 42.09 and 46.13 mg/g, respectively. The kinetics of the biosorption process is found to follow the pseudo-second-order kinetic model. Thermodynamic parameters depict the endothermic nature of biosorption and the process is spontaneous and favorable. Release of cations and protons from the biosorbent during sorption of Cd(II) and Ni(II) reveals that the main sorption mechanism is ion exchange. FTIR analysis demonstrates that carboxyl and hydroxyl groups were involved in the biosorption of the metal ions. The recovery of the Cd(II) and Ni(II) from grapefruit peel is found to be more than 97% using 0.1 M HCl. The results suggest that grapefruit peel can be used effectively for the removal of Cd(II) and Ni(II) ions from wastewaters.
TL;DR: In this article, a one-pot multicomponent reaction for the synthesis of diazepine derivatives in excellent yields is described, where the reactions of various 1,2-diamines, terminal alkynes, and an isocyanide take place in the presence of a catalytic amount of magnetically recoverable silica-supported superparamagnetic Fe3O4 nanoparticles in ethanol.
TL;DR: In this article, the overall heat transfer coefficient of CuO/water nanofluids is investigated experimentally under laminar flow regime (100 ǫ/ǫ, Re  ≥ 1000) in a car radiator.
TL;DR: Commercial chitosan – without any post-modification with active Bronsted or Lewis acid centers – was found to be a highly efficient renewable and recoverable bio-polymer catalyst for the rapid and convenient synthesis of α-amino nitriles or imines from aromatic aldehydes and amines under mild reaction conditions at room temperature in high to quantitative yields.
TL;DR: These results could be utilized to understand the extension and rupture mechanism of coronary arteries and has implications for interventions and surgeries, including balloon-angioplasty, bypass, and stenting.
TL;DR: In this article, the heat transfer performance of the automobile radiator is evaluated experimentally by calculating the overall heat transfer coefficient (U ) according to the conventional ǫ-NTU technique.
TL;DR: A new approach to control, stabilization and disturbance rejection of attitude subsystem of quadrotor is presented in this article, where SISO approach is implemented for control structure to achieve desired objectives, the performance of the designed control structure is evaluated through time domain factors such as overshoot, settling time and integral error index, and robustness.
Abstract: A new approach to control, stabilization and disturbance rejection of attitude subsystem of quadrotor is presented in this article. Analytical method is used to tune conventional structure of PID controller. SISO approach is implemented for control structure to achieve desired objectives. The performance of the designed control structure is evaluated through time domain factors such as overshoot, settling time and integral error index, and robustness. A comparison is done between designed controller and back-step controller applied to main model of quadrotor. The results of simulation show the effectiveness of designed control scheme.
TL;DR: In this paper, the effect of polypropylene fiber (PPF) on both durability, and physical and mechanical characteristics of concrete for application in concrete sleepers was investigated, where compressive, splitting tensile, and three-point flexural strength, and VeeBee Consistometer (VB) tests were performed to indicate physical and physical characteristic of PPF reinforced concrete.
TL;DR: In this paper, FSW was used to join sheets of AA5083 aluminum alloy and commercially pure copper and the effects of process parameters including rotational and welding speeds on the microstructures and mechanical properties of the joints were investigated and different joint defects were analyzed.
TL;DR: Experimental results show good estimation of the SOH of VRLA batteries, and the proposed method is based on the state of charge (SOC) of the battery.
Abstract: This paper presents an online method for the estimation of the state of health (SOH) of valve-regulated lead acid (VRLA) batteries. The proposed method is based on the state of charge (SOC) of the battery. The SOC is estimated using the extended Kalman filter and a neural-network model of the battery. Then, the SOH is estimated online based on the relationship between the SOC and the battery open-circuit voltage using fuzzy logic and the recursive least squares method. To obtain the open-circuit voltage while the battery is operating, the reflective charging process is employed. Experimental results show good estimation of the SOH of VRLA batteries.
TL;DR: In this article, an Artificial Neural Network (ANN) model was developed to simulate the correlation between the friction stir welding parameters and mechanical properties, and the model was employed to predict the ultimate tensile strength and hardness of Butt joint of AA7075-O to AA5083-O aluminium alloys.
TL;DR: In this paper, the edge cracked triangular (ECT) fracture test configuration was used for mixed-mode fracture analysis of Neiriz marble and a generalized maximum tangential stress (GMTS) criterion was used to predict the experimental results.
Abstract: Numerical and experimental studies were performed on a new fracture test configuration called the edge cracked triangular (ECT) specimen. Using several finite-element analyses, the fracture parameters (i.e., K
I, K
II, and T-stress) were obtained for different combinations of modes I and II. The finite-element results show that the ECT specimen is able to provide pure mode I, pure mode II, and any mixed-mode loading conditions in between. Also, a series of mixed-mode fracture experiments were conducted on Neiriz marble rock using the proposed specimen. Furthermore, the generalized maximum tangential stress (GMTS) criterion was used to predict the experimental results. The GMTS criterion makes use of a three-parameter model (based on K
I, K
II, and T) for describing the crack tip stresses. Due to the significant positive T-stresses that exist in the ECT specimen, typical minimum fracture toughness values were expected to be obtained when the ECT specimen is used. The direction of fracture initiation and the path of fracture growth were also obtained theoretically using the GMTS criterion, and good agreement was observed between the experimental fracture path and theoretical simulations. The fracture study of this specimen reveals that the ECT specimen can be also used in mixed-mode fracture studies of rock materials in addition to the conventional circular or rectangular beam test samples.
TL;DR: In this article, a magnetic metal-organic framework (MOF) was proposed for preconcentration of Cd(II) and Pb(II), which was applied to the rapid extraction of trace quantities of cdII and pb(2) ions in fish, sediment, and water samples.
Abstract: We describe a novel magnetic metal-organic framework (MOF) for the preconcentration of Cd(II) and Pb(II) ions. The MOF was prepared from the Fe3O4-pyridine conjugate and the copper(II) complex of trimesic acid. The MOF was characterized by IR spectroscopy, elemental analysis, SEM and XRD. A Box-Behnken design through response surface methodology and experimental design was used to identify the optimal parameters for preconcentration. Extraction time, amount of magnetic MOF and pH value were found to be critical factors for uptake, while type, volume, concentration of eluent, and elution time are critical in the elution step. The ions were then determined by FAAS. The limits of detection are 0.2 and 1.1 μg L−1 for Cd(II), and Pb(II) ions, respectively, relative standard deviations are <4.5% (for five replicates at 50 μg L−1 of Cd(II) and Pb(II) ions), and the enrichment capacity of the MOF is at around 190 mg g−1 for both ions which is higher than the conventional Fe3O4-pyridine material. The magnetic MOF was successfully applied to the rapid extraction of trace quantities of Cd(II) and Pb(II) ions in fish, sediment, and water samples.
TL;DR: In this paper, a multi-mode resource-constrained discrete time-cost-resource optimization (MRC-DTCRO) model is presented to select starting time and the execution mode of each activity satisfying all the project constraints.
TL;DR: In this article, an effective approach for finite-difference time-domain modeling of graphene as a conducting sheet is proposed, where a new technique for implementing a conducting surface boundary condition in the FDTD method is presented.
Abstract: An effective approach for finite-difference time-domain modeling of graphene as a conducting sheet is proposed. First, we present a new technique for implementing a conducting surface boundary condition in the FDTD method; then, the dispersive surface conductivity of graphene is imposed. Numerical examples are presented to show the stability, accuracy, applicability, and advantages of the proposed approach. Validation is achieved by comparison with existing analytic methods.
TL;DR: In this paper, the authors presented the results of a laboratory study which aimed to verify possibility of using electric arc furnace (EAF) steel slag (SS) in substitution of natural limestone (LS) aggregates in warm mix asphalt (WMA) mixture.
TL;DR: In this paper, the effect of graphene nano-platelets (GNPs) on mechanical properties of polymer nanocomposites was investigated using nanoindentation and nanoscratch methods.
TL;DR: This paper uses an organisation called holonic multi-agent system (HMAS) to model a large traffic network and introduces holonic Q-learning to control the signals in both levels.
TL;DR: In this article, a weak form of the governing equation of non-local Euler beams is outlined and the Ritz method is selected in order to analyze the nonlocal beams with arbitrary boundary conditions along them, and analytical formulations are developed to find the stiffness matrix, buckling stiffness matrix and mass matrix.
TL;DR: In this article, the authors considered an EOQ problem under partial delayed payment, where a fraction of the purchasing cost must be paid at the beginning of the period and the remaining amount can be paid later.
Abstract: In many transactions concerning selling and buying, a specified delay of payment is offered or accepted by the seller. This can be regarded as a kind of discount and has potential consequences for the order size. These kinds of effects are not explicitly incorporated in the classical formulas for economic order quantities (EOQ). In this research we consider an EOQ problem under partial delayed payment. A fraction of the purchasing cost must be paid at the beginning of the period and the remaining amount can be paid later. Shortages are permitted and occur as a combination of backorders and lost sales. The aim of this paper is to determine the order and shortage quantities.