Catálogo de publicaciones - libros

In this paper, a lossless watermarking technique in dealing with halftone images is proposed to achieve both copyright protection and exact recovery of the original halftone image with legal authorization. Experimental results show that pattern substitution along with an appropriate block cutting on a halftone image makes possible the positive recovery of the original halftone image after the extraction of a watermark.

Current mode fuzzy-tuning proportional-integral (PI) control of UPS (Uninterruptable Power Supply) inverter is presented in this paper. Double loop current mode and fuzzy logic controller are combined in this control scheme. Double loop current mode control scheme includes two control loops as voltage and current. Output voltage and filter inductor current are used as feedback variables in voltage control loop and current control loop respectively. In voltage control loop, voltage feedback gain is adjusted by fuzzy-logic controller (FLC). The input variables of the FLC are the output voltage error and its derivative and the output variable of the FLC is voltage feedback gain. This control scheme is simulated using C++ and PSIM and implemented using Texas Instruments TMS320LF2407 DSP (Digital Signal Processor). Simulations and implementation are realized under linear, nonlinear and fluorescent loads. The results prove that this control scheme provides low total harmonic distortion (THD) and fast dynamic response

A fuzzy controller to optimize oxic phase of sub-cycle in pilot scale SBR (working volume, 20m^3) located at public swine wastewater treatment plant was investigated. The operation mode of intermittent feeding of raw water and sub-cycle with repeating anoxic-aeration conditions were adapted to avoid the high-strength nitrogen inhibition. In sub-cycle, aeration time for ammonium oxidation was tried to control by fuzzy system using DO value and its differential values for input membership function. In previous study, a lag time of DO profile was proved to be useful for inference of nitrogen loading rates and abrupt raise of DO showed potential ability to detect ending point of ammonia oxidation, however, it also needs proper safety factor for high level DO in lag time or noisy system. Here, the fuzzy system could reduce the complexity of application. As results, the fuzzy system with the simultaneous application of DO value and its differential values was appropriate for the stable control of SBR.

This work proposes cascaded Fuzzy Logic Controllers as new hardware architecture so that it works in an accurate and fast manner. The MAX-MIN interface can be simplified as lookup table operations. Both membership function values and index numbers of input MF’s are pre-stored in the lookup table and the observed crisp inputs serve as the addresses for reading them. Each output MF is treated as a singleton located at the center of the MF. So, the computational complexity of COG defuzzification is significantly reduced. As a case study for a single-phase converter, the fuzzy method of Δ∝ angle compensation is used to linearize the converter transfer characteristics in discontinuous conduction mode. On the basis of the information collected from the graphs; the fine tuning of the output of FLC1 is suggested to achieve better linearization. The required fine-tuning is achieved by using another fuzzy controller FLC2 cascaded with first fuzzy controller FLC1. All components of the FLC are simulated in VHDL using the concept of moment of equilibrium principle for MAX and MIN modules. The VHDL analysis shows faster response to conclude that dedicated cascaded hardware processor will give very accurate linear control for the converter under study.

The aim of this project is to research optimal escape trajectories for aircraft in close ground proximity using a given digital terrain model. Optimal escape trajectories will depend on pilot skills, aircraft performance and as well as other requirements, such as the need to fly low or fast. This paper presents initial results of a project to optimise for a McDonald F-4 Phantom flight trajectories in a hypothetical, digital terrain using a non-linear optimisation method. The 2 outcomes show that different controls result depending on the objectives or constraints.

This research develops an optimal planning model for pump-treat-inject based groundwater remediation systems. Optimizing the design of the pump-treat-inject system is a nonlinear, dynamic and discrete optimization problem. This study integrates the Genetic Algorithm (GA) and Differential Dynamic Programming (DDP) to solve this highly complex problem. The proposed model considers both the cost of installing wells (fixed cost) and the operating cost of pumping, injection and water treatment. Minimizing the total cost and meeting the water quality constraints, the model computes the optimal number and location of wells, as well as the associated optimal pumping and injection schemes. This work also investigates many factors that affect the optimal design of a remediation system, such as, various numerical cases revealing the time-varying pumping and injection rate, and the requirement to balance the total volume between pumping and injection that can significantly influence the optimal design.

This paper addresses the robot selection problem by using a multi-criteria decision making approach based on the Choquet integral. The key feature of the Choquet integral is that it can incorporate interaction among attributes into the decision analysis, an issue that has been generally overlooked in earlier robot selection studies. The proposed decision framework makes use of the information previously elicited from experts analyzing a reference set of robot alternatives with the same selection criteria as in the current evaluation, and applies the Choquet integral to determine the most suitable robot. A comprehensive illustrative example is presented using a previously published data set, and the results obtained using the proposed approach are compared with those of another multi-criteria decision aid, which has been also employed in earlier studies addressing robot selection.

This paper describes a comparative evaluation of two fuzzy-derived techniques for modelling fuel spray penetration in the cylinders of a diesel internal combustion engine. The first model is implemented using conventional fuzzy-based paradigm, where human expertise and operator knowledge were used to select the parameters for the system. The second model used an adaptive neuro-fuzzy inference system (ANFIS), where automatic adjustment of the system parameters is effected by a neural networks based on prior knowledge. Two engine operating parameters were used as inputs to the model, namely in-cylinder pressure and air density. Spray penetration length was modelled on the basis of these two inputs. The models derived using the two techniques were validated using test data that had not been used during training. The ANFIS model was shown to achieve an improved accuracy compared to a pure fuzzy model, based on conveniently selected parameters.

This study proposed the integrating architecture of knowledge information systems using intelligent agent. We analyzed the basic architecture of e-Learning system and digital library. We also classified the modules that can effectively integrate the each function of e-Learning and digital library. Through these analysis and classification, we designed the integrating architecture of e-Learning with digital library. We also described the roles and structures based on intelligent agent to be unified between e-Learning system and digital library. Especially, we proposed the integrating strategies of user modeling and learning metadata as the integrating architecture for contents sharing. Furthermore we provided a new integrating model for contributing the knowledge enlargement and the mutual prosperity between e-Learning and digital library.

Today, there are multiple approaches that serve as guide for the elaboration of an system by means of theoretical viewpoints as constructivism. However, these approaches are not fit for stating, in a clear and solid way, their basic pedagogical principles. The analyses of the approaches though this paper aims to link the concepts that they present with the specific pedagogical concepts that, in the authors’ opinion, they include. In this way, it is intended to show that this type of proposals should be explicitly sustained by the educative theories that they contain, therefore they would act as a theoretical grounding for developers of systems, who would then perform their choices with a pedagogical basis.