Sharif Digital Repository

In this study, a novel network reinforcement model incorporating optimal wind farms (WFs) integration to power systems is proposed. Based on the reinforcement model, new transmission lines are added to the network for eliminating the transmission network congestion. In addition, a methodology for determining the WFs optimal capacities, the economical WF lines transfer rates and the appropriate reinforcement plan, whereas maximising the total benefit using cost-reliability analysis is presented. In this way, the objective of the proposed optimisation problem has been divided into a master problem and two subproblems. Benders decomposition is employed to connect the master and subproblems of... 

Investigations have shown the traces of antibiotics in surface water, groundwater, wastewater treatment plants, and drinking water. However, conventional wastewater treatment is not entirely effective for vancomycin degradation. Advanced oxidation is one of the most widespread methods of antibiotic degradation in aqueous media. Vancomycin was quantified by high-performance liquid chromatography. The Response Surface Methodology (RSM) based on Central Composite Design (CCD) was used to explore and optimise the effect of the independent variables on vancomycin degradation. Independent variables were as follows: pH (3–11), vancomycin concentration (15–75 mg/L), TiO2–clinoptilolite (25–125 mg in... 

This article deals with solving distributed optimization problems with equality constraints by a class of uncertain nonlinear heterogeneous dynamic multiagent systems. It is assumed that each agent with an uncertain dynamic model has limited information about the main problem and limited access to the information of the state variables of the other agents. A distributed algorithm that guarantees cooperatively solving of the constrained optimization problem by the agents is proposed. Via applying this algorithm, the agents do not need to continuously broadcast their data. It is shown that the proposed algorithm can be useful in solving resource allocation problems. IEEE  

In this paper, we focus on the problem of hierarchical cross- layer dynamic resource allocation for heterogeneous networks with flexible backhaul. We formulate the radio resource management problem as a two timescale non-convex stochastic optimisation problem which jointly optimizes flow control, routing control, interference mitigation and link scheduling in order to maximize a generic network utility. We propose an iterative hierarchical control structure where the long-term controls are adaptive to large scale fading and the short-term control is adaptive to the local CSI within a pico or macro BS, to find the optimal solution. The proposed solution benefits from low complexity and... 

One of the main advantages of utilizing flexible backhaul in future HetNets is that it can provide better user experience through flexible resource allocation. For this purpose, it is important to provide the required quality of service (QoS) in such networks. In this paper, we consider the problem of cross-layer radio resource management in HetNets with flexible backhaul which guarantees minimum total transmit power of BSs as well as the average end-to-end data rate requirement of each data flow. The problem is formulated as a two-timescale stochastic optimisation, where the long-timescale control variables are flow control, routing control and interference mitigation, while the... 

In this study, a new 12-slot two-saliency variable reluctance (VR) resolver with simple non-overlapping windings is proposed. The excitation winding in the proposed resolver is replaced with one axial coil that is perpendicular to the signal windings. Both distributed and non-overlapping concentric windings with uniform coil turns are used. The rotor has two upper and lower saliencies located in front of each other. The shape and width of each saliency are determined based on the optimisation. Compared with conventional 12-slot VR resolvers, the proposed resolver has a simpler rotor structure and the advantages of two-saliency resolvers against eccentricity, absolute output position, and... 

This study presents a set of rules for optimal tuning of a class of integer-order controllers, known as implementable fractional-order PID controllers, so that they can be employed to control First Order Plus Dead Time (FOPDT) processes. To this end, "tuning based on the implementable form of the controller"is an approach that has been applied instead of the common approach of "tuning based on the ideal form of the controller". Consequently, no contradiction is found between the behavior of the tuned controller and that of the implemented controller. Also, algebraic relations between the values of cost functions, which are defined based on Integral Square Error (ISE) and Integral Square Time... 

We propose a time-varying dual accelerated gradient method for minimizing the average of n strongly convex and smooth functions over a time-varying network with n nodes. We prove that the time-varying dual accelerated gradient ascent method converges at an R-linear rate with the time to reach an ϵ-neighborhood of the solution being of O([Formula presented]ln⁡[Formula presented]), where c is a constant depending on the graph and objective function parameters and M is a constant depending on the initial values. We test the proposed method on two classes of problems: L2-regularized least squares and logistic classification problems. For each class, we generate 1000 problems and use the... 

This contribution focuses on the use of ladder particle swarm optimisation (LPSO) on modelling of oxadiazole- and triazolesubstituted naphthyridines as human immunodeficiency virus-1 integrase inhibitors. Artificial neural network (ANN) and Monte Carlo cross-validation techniques were combined with LPSO to develop a quantitative structure-activity relationship model. The techniques of LPSO, ANN and sample set partitioning based on joint x-y distances were applied as feature selection, mapping and model evaluation, respectively. The variables selected by LPSO were used as inputs of Bayesian regularisation ANN. The statistical parameters of correlation of deterministic, R2, and... 

Global warming is currently one of the biggest concerns worldwide; hence, addressing this issue is a trending topic among the research community. Escalating global warming through the wasted energy (30% of its input chemical energy) from internal combustion engines (ICEs) by exhaust emission is a major issue that should be considered. One way to reduce the waste of energy from ICEs is to recover the heat using a thermodynamic cycle. Using this method, not only does the engine power increase but also the fuel consumption decreases. Toward this end, and in this study, the organic Rankine cycle (ORC) and high-temperature Kalina cycle (HTKC), which have been previously used for other purposes,... 

Purpose: This study aims to deal with supplier selection problem. The supplier selection problem has significantly become attractive to researchers and practitioners in recent years. Many real-world supply chain problems are assumed as multiple objectives combinatorial optimization problems. Design/methodology/approach: In this paper, the authors propose a multi-objective model with fuzzy parameters to select suppliers and allocate orders considering multiple periods, multiple resources, multiple products and two-echelon supply chain. The objective functions consist of total purchase costs, transportation, order and on-time delivery, coverage and the weights of suppliers. Distance-based... 

Both governments and health-related organizations must immediately act after a natural disaster happened, i.e., providing essential equipment and medicines to injured people as soon as possible and adequately. To achieve this goal, planning the distribution and the inventory of crucial items during a scenario of disasters, a relief supply chain network with four echelons, namely suppliers, warehouses, disaster locations, and medical centers, is designed. In this work, a bi-objective nonlinear mathematical model that follows two main concerns is proposed. First, we wish to minimize the supply chain costs in terms of both the traveling time between echelons and the inventory costs. Second, we... 

The major application of stochastic intelligent methods in optimisation, control and management of complex systems is transparent. Many researchers try to develop collective intelligent techniques and hybrid meta-heuristic models for improving the reliability of such optimisation algorithms. In this paper, a new optimisation method that is the simulation of 'the great salmon run' (TGSR) is developed. This simulation provides a powerful tool for optimising complex multi-dimensional and multi-modal problems. For demonstrating the high robustness and acceptable quality of TGSR, it is compared with most of the well-known proposed optimisation techniques such as parallel migrating genetic... 

A new mathematical model for the capacitated multi-facility location-allocation problem with probabilistic customers' locations and demands is developed in this article. The model is formulated into the frameworks of the expected value model (EVM) and the chance-constrained programming (CCP) based on two different distance measures. In order to solve the model, two hybrid intelligent algorithms are proposed, where the simplex algorithm and stochastic simulation are the bases for both algorithms. However, in the first algorithm, named SSGA, a special type of genetic algorithm is combined and in the second, SSVDO, a vibration-damping optimisation (VDO) algorithm is united. The Taguchi method... 

Nanostructured TiO2-ZrO2 thin films and powders were prepared by a straightforward aqueous particulate sol-gel route. Titanium (IV) isopropoxide and zirconium (IV) acetate hydrate were used as precursors, and hydroxypropyl cellulose was used as a polymeric fugitive agent in order to increase the specific surface area. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy revealed that the powder were crystallised at the low temperature of 500 °C, containing anatase-TiO 2 and tetragonal-ZrO2 phases. Furthermore, it was found that ZrO2 retarded the anatase-to-rutile transformation up to 900 °C. The activation energies for crystallite growth of TiO2 and ZrO2 components in... 

In this paper, the impacts of Maxwell nanoliquid transmission, rectangular with titanium oxide nanoparticles are explored over the triangular, chamfer blades. The innovation of this paper is the use of the number of chamfers, rectangular, and triangular blades at the top and bottom of a stretched plate to study physical nanofluid parameters such as temperature and the effects of magnetism. Also, by determining the appropriate height and length for the blades, we achieve the best optimization of temperature and velocity of nanofluid between the plate and the blades, which improves heat transfer and with a more and better effect of magnetic effects. The finite element method is utilized for... 

This study presents a novel framework to incorporate the uncertainties associated with load fluctuations and components' availability in a day-ahead joint energy-reserve payment cost minimisation (PCM). The payments are calculated based on locational marginal prices (LMPs). Considering these uncertainties, appropriate definitions are not available for energy and reserve LMPs (RLMPs) that suit the probabilistic PCM formulation and reflect the market characteristics. A tri-level optimisation framework is proposed. The optimisation variables in the first-level optimisation include commitment status. In the second-level optimisation, the production schedule and allocated reserves are the... 

Water cycle algorithm (WCA) is a population-based metaheuristic algorithm, inspired by the water cycle process and movement of rivers and streams towards sea. The WCA shows good performance in both exploration and exploitation phases. Further, the relationship between improvised exploitation and each parameter under asymmetric interval is derived and an iterative convergence of WCA is proved theoretically. In this paper, CEC’15 computationally expensive benchmark problems (i.e., 15 problems) have been considered for efficiency measurement of WCA accompanied with other optimisers. Also, a new discretisation strategy for the WCA has been proposed and applied along with other optimisers for... 

The current paper presents a simple mathematical model for replication of the transient acceleration motion of displacement hulls in calm water under the action of a propulsion system. Different empirical methods are coupled, and an operational speed problem is solved in the time domain. The resistance of the ship is calculated by using the Holtrop method. The values of thrust force, torque and propeller efficiency are computed by using B-Series empirical equations. The acceleration motion of the vessel, which is triggered as the engine starts to work, is simulated by solving a set of first-order differential equations, which are discretised in the time domain. It is shown that different... 

The objective of this paper is to provide optimization of falling film Li/Br solution on a horizontal single tube based on minimization of entropy generation. Flow regime is considered to be laminar, the effect of boiling has been ignored and wall temperature is constant. Velocity, temperature and concentration distributions are numerically determined and dimensionless correlations are obtained for predicting the average heat transfer coefficient and average evaporation factor on the horizontal tube. Thermodynamic imperfection due to passing lithium bromide solution is attributed to non-isothermal heat transfer; fluid flow friction and mass transfer irreversibility. Scale analysis shows that...