Search results for " optimization"

Robust control of stochastic systems against bounded disturbances with application to flight control

2014

This paper investigates the problems of state observer design and observer-based integral sliding-mode control (SMC) for a class of Itô stochastic systems subject to simultaneous input and output disturbances. A new type of sliding-mode-based descriptor observer method is developed to approximate the system state and disturbance vectors. An integral-type SMC scheme is proposed based on the state estimation to stabilize the overall system. The main contributions of this approach are as follows: 1) The desired estimations of state and disturbance vectors can be obtained simultaneously, and 2) in the designed sliding-mode observer, the integral term of the Itô stochastic noise is eliminated …

Optimum design for work-hardening adaptation

1977

Abstract The finite element-linear programming approach and the work-hardening adaptation criterion are used to formulate a general theory of optimum design of rigid-work-hardening structures subjected to loads which vary statically within given limits. Self-weight, as well as some technological constraints, can be introduced into the framework of the optimization problem. The optimality conditions are discussed with the aid of geometrical descriptions as well, and a comparison is made with the standard limit design. Numerical applications are given for a plane truss and a plane frame with axial force-bending moment interaction.

Robust Predictive Control of a variable speed wind turbine using the LMI formalism

2014

This paper proposes a Robust Fuzzy Multivariable Model Predictive Controller (RFMMPC) using Linear Matrix Inequalities (LMIs) formulation. The main idea is to solve at each time instant, an LMI optimization problem that incorporates input, output and Constrained Receding Horizon Predictive Control (CRHPC) constraints, and plant uncertainties, and guarantees certain robustness properties. The RFMMPC is easily designed by solving a convex optimization problem subject to LMI conditions. Then, the derived RFMMPC applied to a variable wind turbine with blade pitch and generator torque as two control inputs. The effectiveness of the proposed design is shown by simulation results.

fuzzy approach to the robust facility layout in uncertain production environments

2001

The proposed method approaches the problem of the optimal facility layout using fuzzy theory. The optimal layout is a robust layout that minimizes the total material handling cost, when the product market demands are uncertain variables, which are defined as fuzzy numbers. Since each department has a limited production capacity, not all possible combinations, deriving from each product's market demand, are taken into account because some combination could exceed the overall department's productivity. Therefore, the optimal solution results by solving a 'constrained' fuzzy optimization problem, in which the fuzzy material handling costs corresponding to the layouts are evaluated, and a ranki…

Economic analysis on dynamic photovoltaic systems in new Italian “feed in tariffs” context

2013

Dynamic photovoltaic generators, based on the application of solar-trackers, are able to give an increment to the electric energy production from solar source. Their realization and maintenance costs are certainly higher than those of fixed ones. In this paper the Authors propose a method to estimate the increment of electrical energy generation that must be guaranteed by a dynamic photovoltaic generator, so as its realization could be more favorable with respect to that of a fixed generator one with the same rated power. This method, developed by means of classical economic indexes like the Pay-Back-Period and the Net Present Value, takes in to account the economic incentives for the PV sy…

An efficient analytical approach for obtaining a five parameters model of photovoltaic modules using only reference data

2013

Exploiting the equivalent one-diode circuit of a photovoltaic (PV) module, this paper proposes a novel and fully analytical model to predict the electrical performance upon solar irradiance intensity and PV module temperature. The model refers essentially to an equivalent circuit governed by five parameters and the extraction of them permits to describe the current–voltage curve of the PV panel and consequently permits to assess the energy output of PV modules. The proposed model extracts the five characteristic parameters using only exact analytical relationship and tabular data always available such as short-circuit current, open circuit voltage and the Maximum Power Point (MPP). The diff…

2014

This paper presents a mathematical model for robust production planning. The model helps fashion apparel suppliers in making decisions concerning allocation of production orders to different production plants characterized by different lead times and production costs, and in proper time scheduling and sequencing of these production orders. The model aims at optimizing these decisions concerning objectives of minimal production costs and minimal tardiness. It considers several factors such as the stochastic nature of customer demand, differences in production and transport costs and transport times between production plants in different regions. Finally, the model is applied to a case study.…

Robust Multi-Objective Optimal dispatch of Distributed Energy Resources in Micro-Grids

2011

Modern distribution systems are implemented through micro grids: small power networks where generation is close to consumption and ICT supports the coordinated management of the different energy resources. In such systems, the central control unit manages energy dispatch from the different sources according to different criteria (technical, economical and environmental) and takes care of tertiary regulation. Such optimization for the tertiary regulation is performed with a time interval that typically is of 24 hours. This is due to the fact that it is necessary to take into account the charge and discharge cycles of storage systems. On the other hand, such long time leads to large errors in…

Multi-Objective Design of Optimisation of a Class of PKMs - The 3-DOF Gantry-Tau

2010

The main contribution of this paper is the use of the evolutionary multi-objective methodology based on the com plex search algorithm and geometric approaches to optimise a parallel kinematic structure. The design optimisation scheme includes the kinematic (collisions free workspace), elastostatic (Cartesian stiffness in the Y direction) and elastodynamic (first resonance frequency) properties of the PKM as the objectives. The optimisation constraints are the support frame lengths, actuator positions, end-effector’s kinematic parameters and the robot’s arm lengths. The optimisation results are presented in this paper.

LPV models: Identification for gain scheduling control

2001

In this paper the use of discrete-time Linear Parameter Varying (LPV) models for the gain scheduling control and identification methods for non-linear or time-varying system is considered. We report an overview on the existing literature on LPV systems for gain scheduling control and identification. Moreover, assuming that inputs, outputs and the scheduling parameters are measured, and a form of the functional dependence of the coefficients on the parameters is known, we show how the identification problem can be reduced to a linear regression so that a Least Mean Square and Recursive Least Square identification algorithm can be reformulated. Our methodology is applied for the identificatio…