Abstract The problem of aircraft trajectory planning is formulated as a hybrid optimal control problem. The aircraft is modeled as a switched system, that is, a class of hybrid dynamical systems. The sequence of modes...
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Abstract The problem of aircraft trajectory planning is formulated as a hybrid optimal control problem. The aircraft is modeled as a switched system, that is, a class of hybrid dynamical systems. The sequence of modes, the switching times, and the inputs for each mode are the control variables. An iterative bi-level optimization algorithm is employed to solve the optimal control problem. At the lower level, given a pre-defined sequence of flight modes, the optimal switching times and the input for each mode are determined. This is achieved by extending the continuous state to include the switching times and then solving a conventional optimal control problem for the extended state. At the higher level, the algorithm modifies the mode sequence in order to decrease the value of the cost function. We illustrate the utility of the problem formulation and the solution approach with two case studies in which short horizon aircraft trajectories are optimized in order to reduce fuel burn while avoiding hazardous weather.
Synthesis of musical instruments or human voice is a time consuming process which requires theoretical and experimental knowledge about the synthesis engine. Commonly, performers need to deal with synthesizer interfac...
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The problem of robust H ∞ filtering for uncertain two-dimensional (2-D) continuous systems described by the Roesser state-space model is investigated when the parameter uncertainties are polytopic. A sufficient line...
The problem of robust H ∞ filtering for uncertain two-dimensional (2-D) continuous systems described by the Roesser state-space model is investigated when the parameter uncertainties are polytopic. A sufficient linear matrix inequality (LMI) condition for the existence of a 2-D continuous filter such that, for all admissible uncertainties, the error system is asymptotically stable, and the H ∞ norm of the transfer function from the noise signal to the estimation error is below a prespecified level. A sequence of standard LMI conditions that ensure the existence of homogeneous polynomially parameter-dependent (HPPD) matrices of arbitrary degree, that are solutions to the parameter-dependent LMIs is provided in terms of the vertices of the polytope. The proposed method includes results in the quadratic framework and the linearly parameter-dependent framework as special cases. Finally, an example is provided to demonstrate the effectiveness and advantages of the proposed filter design methodology.
This article explores, through a case study, measures of energy efficiency in data processing centers. An analysis of this case demonstrates how the design criteria could improve the rate of consumption in IT centers,...
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This article explores, through a case study, measures of energy efficiency in data processing centers. An analysis of this case demonstrates how the design criteria could improve the rate of consumption in IT centers, which is currently the second most contaminating industry on the planet, and is the responsible for 2% of CO2 emissions, surpassed only by the aeronautical industry. The present and future situation of IT center energy consumption and associated environmental effects is analyzed, and also looks at how state-of-the-art technology, correctly implemented, could ensure significant rationalization of data processing center energy consumption. The article will examine optimization techniques, specific problems and case studies.
This paper presents a distributed event-based control strategy for a networked dynamical system consisting of N linear time-invariant interconnected subsystems. Each subsystem broadcasts its state over the network acc...
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ISBN:
(纸本)9781612848006
This paper presents a distributed event-based control strategy for a networked dynamical system consisting of N linear time-invariant interconnected subsystems. Each subsystem broadcasts its state over the network according to some triggering rules which depend on local information only. The system converges to an adjustable region around the equilibrium point under the proposed control design, and the existence of a lower bound for the broadcasting period is guaranteed. The effect of the coupling terms over the region of convergence and broadcasting period lower bound is analyzed, and a novel model-based approach is derived to reduce the communications. Simulation results show the effectiveness of the proposed approaches and illustrate the theoretical results.
This paper examines the control of the heeling angle of a ship in still waters based on the utilisation of anti-heeling tanks operated by pressurized air. The proposed objective attempts to reduce the list angle to a ...
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This paper examines the control of the heeling angle of a ship in still waters based on the utilisation of anti-heeling tanks operated by pressurized air. The proposed objective attempts to reduce the list angle to a null value during the loading process in a fast ferry ship. A nonlinear adaptive controller has been designed as a means of counteracting the parameter inaccuracies that are involved in the nonlinear model. These are the linear and quadratic damping coefficients and the size of the cargo that is being handled. The design is based on a relatively new methodology, the backstepping procedure. With the objective of reducing the number of sensors a model reference based nonlinear observer has been introduced. The controller thus designed provides a robust control system under parametric uncertainties and state variable errors. The designed control implies an improvement on the actual systems based on the PID control implemented under programmable logic controllers (PLCs).
Complex chemical reaction networks often exhibit different dynamic behaviour on different time scales. A combined approach is proposed in this work for determining physically meaningful mass action realizations of com...
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In this paper nonlinear time-varying and bilinear discrete-time systems with additive bounded disturbances are considered. First, conditions guaranteeing uniform ultimate boundedness for time-varying nonlinear systems...
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ISBN:
(纸本)9781612848006
In this paper nonlinear time-varying and bilinear discrete-time systems with additive bounded disturbances are considered. First, conditions guaranteeing uniform ultimate boundedness for time-varying nonlinear systems are established. Then, algebraic conditions ensuring the existence of polyhedral Lyapunov functions, uniform boundedness and positive invariance for closed-loop bilinear systems are obtained. Finally, these results are applied to various robust stabilization problems for bilinear systems subject to persistent additive disturbances. It is shown that these problems can be reduced to a single or a series of linear programming problems.
Electrical Impedance Tomography (EIT), and in particular its application to pulmonary measurement, has been the subject of intensive research since its development in the early 1980s by Barber and Brown. One of the re...
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The extraction and representation of information from volume data are important research avenues in computer-based visualization. The interpretation of three- or multi-dimensional data from various scanning devices is...
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The extraction and representation of information from volume data are important research avenues in computer-based visualization. The interpretation of three- or multi-dimensional data from various scanning devices is important to medical imaging, diagnosis and treatment, reliability and sustainability analyses in various industrial branches, and, in more general terms, information visualization. In this paper, we present several approaches for the classification and representation of relevant information from volume data sets. The techniques are based on the gradient vector, a property directly derived from the original volume data. We show how this property can be computed and subsequently used for classification through gradient-based one- and multi-dimensional transfer functions, as well as for the enhancement of surface features. The described techniques are illustrated through images generated using our volume rendering framework, from Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) data sets. The resulting images show how gradient-based techniques are suited for improved volume classification and the better extraction of meaningful information.
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