Sharif Digital Repository

Ontology Aligning is an answer to the problem of handling heterogenous information on different domains. After application of some measures, one reaches a set of similarity values. The final goal is to extract mappings. Our contribution is to introduce a new genetic algorithm (GA) based extraction method. The GA, employs a structured based weighting model, named "coincidence based model", as its fitness function. In the first part of the paper, some preliminaries and notations are given and then we introduce the coincidence based weighting. In the second part the paper discusses the details of the devised GA with the evaluation results for a sample dataset  

In this paper an extended approach to the nonlinear DMC algorithm is proposed, which can handle constrained and MIMO systems under some defined conditions. This extension also admits higher control, M, and prediction, P, horizons that are required to increase the performance of the controller in most practical applications. Simulation results of the proposed method in the control of a stirred tank reactor with 2 inputs and 2 outputs nonlinear model are presented to illustrate effectiveness of the method and its justification. © 2003 IEEE  

In this paper, an extended approach to the nonlinear DMC algorithm is proposed, which can handle constrained and MIMO systems under some defined conditions. This extension also admits higher control horizon, M and prediction horizon, P that are required to increase the performance of the controller in the most practical applications. Simulation results of the proposed method in the control of a stirred tank reactor with 2 inputs, 2 outputs nonlinear model and also a power unit nonlinear model with 3 inputs, 3 outputs are presented to illustrate effectiveness of the method and its justification. © 2005 Elsevier Ltd. All rights reserved  

In this paper, the convergence and stability conditions of extended DMC in the control of nonlinear SISO and MIMO systems are investigated. The formulations are based on the ordinary DMC in which, with successive linearization of the nonlinear model and new interpretation of disturbance, the nonlinear extension is deduced. In addition, new convergence and stability criteria are derived for SISO and MIMO systems. These criteria include convergence and stability in the case of longer control (M > 1) and prediction (P > 1) horizons, as well as the finite and infinite sampling time. Finally, the simulation results for a MIMO (3 × 3) model, based on a power unit nonlinear plant, are presented. ©... 

An approximated quadratic programming optimization is proposed to determine a model predictive controller to guarantee end-to-end delay in the DiffServ architecture. The proposed algorithm, called the suboptimal model predictive control scheduler (SMPCS), regulates the service rates of aggregated traffic classes dynamically, such that some constraints on proportional or absolute delay can be guaranteed. This paper investigates SMPCS complexity and its implementation problems in high-speed routers. The main problem of model predictive control (and one which has limited its use to slow processes) is its complexity. Optimization is the most computationally complex part in a model predictive... 

An increasing number of different applications face the challenge of providing end-to-end quality of service (QoS) support such as bandwidth, delay, jitter, and packet loss. In this paper, we have focused on DiffServ architecture to improve its accuracy. We proposed a new algorithm, called Adaptive Model Predictive Control Scheduler (AMPCS), to schedule differentiated buffers in routers, using Adaptive Model Predictive Control as the controller. AMPCS regulates the service rates of aggregated traffic classes dynamically in a way that some constraints on proportional delay or absolute delay can be guaranteed. Our contribution is to apply a model predictive controller to the scheduling problem... 

An approximated quadratic programming algorithm is proposed to determine a model predictive controller, which is applied to the scheduling problem. We name the algorithm Sub-optimal Model Predictive Control Scheduler (SMPCS). The SMPCS prepares a platform to guarantee end to end proportional delay in DiffServ architecture. This paper investigates the complication of SMPCS and its implementation problems in high speed routers. In order to efficiently implement the controller we admit sub-optimal results against reduction in the complexity of the optimizer. Simulation results show that the proposed approximation improves speed of the controller considerably. © Springer-Verlag Berlin Heidelberg... 

In this paper, adaptive model predictive control is applied to schedule differentiated buffers in routers. The proposed algorithm, adaptive model predictive control scheduler (AMPCS), dynamically regulates the service rates of aggregated traffic classes. This algorithm guarantees some required constraints on proportional or absolute delay. The control parameters and the way they are adjusted as well as the problems of implementing the controller at high data rates are investigated. Theoretical analysis and numerical simulations demonstrate stability of AMPCS and its acceptable quality of service differentiations at core routers while maintaining end to end delay constraints. © 2007 Elsevier... 

Adaptive Model Predictive Transmission Control Protocol (AMP-TCP) as a new TCP delay-based congestion control algorithm is introduced. Both aspects of design and implementation of the algorithm are described using simulations on the ns-2 network simulator. The design stage is composed of two steps. First, a recursive system identification approach is proposed to capture the network delay dynamics from TCP source view. Second, the proposed modeling is employed to develop an adaptive model predictive TCP congestion control strategy in the absence of any explicit congestion notification. The characteristics and performance of AMP-TCP are investigated using several network simulations. Finally a... 

Transmission Control Protocol (TCP) uses multiple timers to do its work. The most important of these is the retransmission timer. In this paper, the TCP retransmission timer adjustment mechanism is approached from a system point of view and a new mechanism is proposed. A simple recursive system identification algorithm is used to capture both time variant and time invariant Internet behavior. Also a dynamic model-based Round-Trip Time (RTT) predictor was provided. Based on network simulation and real Internet data collection, it was observed that when the retransmission timer is adjusted by the proposed predictor instead of the traditional RTT estimator, performance increased significantly  

Using a non-linear model in model predictive control (MPC) changes the control problem from a convex quadratic programme to a non-convex non-linear problem, which is much more challenging to solve. In this study, we introduce an MPC algorithm for non-linear discrete-time systems. The systems are composed of a linear constant part perturbed by an additive state-dependent non-linear term. The control objective is to design a state-feedback control law that minimises an infinite horizon cost function within the framework of linear matrix inequalities. In particular, it is shown that the solution of the optimisation problem can stabilise the non-linear plants. Three extensions, namely,... 

Ontology matching is a process for selection of a good alignment across entities of two (or more) ontologies. This can be viewed as a two-phase process of (1) applying a similarity measure to find the correspondence of each pair of entities from two ontologies, and (2) extraction of an optimal or near optimal mapping. This paper is focused on the second phase and introduces our evolutionary approach for that. To be able to do so, we need a mechanism to score different possible mappings. Our solution is a weighting mechanism named coincidence-based weighting. A genetic algorithm is then introduced to create better mappings in successive iterations. We will explain how we code a mapping as... 

Ontology Alignment is a process for finding related entities of different ontologies. This paper discusses the results of our research in this area. One of them is a formulation for a new structural measure which extends famous related works. In this measure with a special attention to the transitive properties, it is tried to increase recall with less harm on precision. Second contribution is a new method for compound measure creation without any need to the mapping extraction phase. Effectiveness of these ideas is discussed and quantitative evaluations are explained in this paper. Copyright © 2006, Hassan Abolhassani, Babak Bagheri Hariri, & Seyed H. Haeri  

This paper studies the real-time energy management of large-scale residential households and standalone electric vehicles charging stations using a non-cooperative game based on consensus protocol. We consider a set of aggregators, each equipped with a processor, to minimize its own cost function by having access to the local estimation terms of neighboring aggregators. Since the cost function of each aggregator is affected by strategy of other aggregators through total generation cost, such interaction among competitive agents is modeled as a non-cooperative game. An idea based on model predictive control is utilized to deal with highly random behavior of users. In this paper, a time-of-use... 

Liquefaction-induced lateral spreading has imposed severe damages to many important structures supported on pile foundations during past earthquakes. As a result, evaluation of pile response to lateral spreading is an important step towards safe and resistant design of pile foundations against this destructive phenomenon. Current paper aims to study the response of a group of piles subjected to liquefaction-induced lateral spreading using a large scale 1-g shake table test. General test results including time-histories of accelerations, pore water pressures, displacements and bending moments are presented and discussed in this paper. In addition, distribution of lateral soil pressure on... 

In this research, two shake table experiments were conducted to study the effects of non-liquefiable crust layer and superstructure mass on the responses of two sets of 2 × 2 pile groups to liquefaction-induced lateral spreading. In this regard, an inclined base layer overlain by a very loose liquefiable layer was constructed in both models; while only in one model, a non-liquefiable crust layer was built. A lumped mass, being representative of a superstructure, was attached to the cap of one pile group in both models. The models were fully instrumented with various sensors, including acceleration, displacement, and pore water pressure transducers. Also, the piles were instrumented with pair... 

The mechanism of crack propagation in concrete specimens containing cracks under shear loading conditions is studied. The shear box test of pre-cracked (double edge cracks) concrete specimens is carried out under laboratory conditions. The higher order displacement discontinuity formulation and the special crack tip elements for the treatment of crack ends is used to numerically simulate the crack propagation mechanism of brittle solids under direct shear loading. A special modeling technique is also proposed to take into account the effect of crack overlapping on the fracturing process of the bridge area in between the two parallel cracks. In this study, the wing cracks are produced at the... 

The overall performance of a linear model predictive controller depends on proper adjustment of several design parameters. Most of these parameters have interdependent effects, which make their trial and error based tuning procedure very difficult. A systematic approach to overcome this problem is to reduce the number of adjustable parameters. This reduction is usually performed on the basis of sensitivity analysis, stability considerations or other objectives and constraints. The most reliable parameter, which can be independently tuned for performance improvement, is the control move suppression coefficient, λ. In this paper, some tuning rules for adjusting this parameter, on the basis of... 

Proportional and integral (PI) control parameters are determined by approximating a dynamic matrix control (DMC). Since accuracy of the approximation depends on DMC parameters in a complicated manner, a combination of direct and indirect optimization methods are employed in this paper. Quadratic programming (QP) is used to determine PI parameters, and a simple grid method is used to find optimal DMC parameters. A tuning formula for the PI controller based on a curve-fitting technique, is suggested. Computer simulations are performed to compare performance of the new PI design method with those achievable using some existing PI controllers. © 2005, Sage Publications. All rights reserved  

This letter introduces a consensus-based generalized multi-population aggregative game coordination approach with application to electric vehicles charging under transmission line constraints. The algorithm enables agents to seek an equilibrium solution while considering the limited infrastructure capacities that impose coupling constraints among the users. The Nash-seeking algorithm consists of two interrelated iterations. In the upper layer, population coordinators collaborate for a distributed estimation of the coupling aggregate term in the agents' cost function and the associated Lagrange multiplier of the coupling constraint, transmitting the latest updated values to their population's...