Integration of modular process simulators under the Generalized Disjunctive Programming framework for the structural flowsheet optimization

The optimization of chemical processes where the flowsheet topology is not kept fixed is a challenging discrete-continuous optimization problem. Usually, this task has been performed through equation based models. This approach presents several problems, as tedious and complicated component properties estimation or the handling of huge problems (with thousands of equations and variables). We propose a GDP approach as an alternative to the MINLP models coupled with a flowsheet program. The novelty of this approach relies on using a commercial modular process simulator where the superstructure is drawn directly on the graphical use interface of the simulator. This methodology takes advantage of modular process simulators (specially tailored numerical methods, reliability, and robustness) and the flexibility of the GDP formulation for the modeling and solution. The optimization tool proposed is successfully applied to the synthesis of a methanol plant where different alternatives are available for the streams, equipment and process conditions.

COMPENDIUM: una herramienta de generación de resúmenes modular

En este artículo presentamos COMPENDIUM, una herramienta de generación de resúmenes de textos modular. Esta herramienta se compone de un módulo central con cinco etapas bien diferenciadas: i) análisis lingüístico; ii) detección de redundancia; iii) identificación del tópico; iv) detección de relevancia; y v) generación del resumen, y una serie de módulos adicionales que permiten incrementar las funcionalidades de la herramienta permitiendo la generación de distintos tipos de resúmenes, como por ejemplo orientados a un tema concreto. Realizamos una evaluación exhaustiva en dos dominios distintos (noticias de prensa y documentos sobre lugares turísticos) y analizamos diferentes tipos de resúmenes generados con COMPENDIUM (mono-documento, multi-documento, genéricos y orientados a un tema). Además, comparamos nuestro sistema con otros sistemas de generación de resúmenes actuales. Los resultados que se obtienen demuestran que la herramienta COMPENDIUM es capaz de generar resúmenes competitivos para los distintos tipos de resúmenes propuestos.

Robust linear semi-infinite programming duality under uncertainty

In this paper, we propose a duality theory for semi-infinite linear programming problems under uncertainty in the constraint functions, the objective function, or both, within the framework of robust optimization. We present robust duality by establishing strong duality between the robust counterpart of an uncertain semi-infinite linear program and the optimistic counterpart of its uncertain Lagrangian dual. We show that robust duality holds whenever a robust moment cone is closed and convex. We then establish that the closed-convex robust moment cone condition in the case of constraint-wise uncertainty is in fact necessary and sufficient for robust duality. In other words, the robust moment cone is closed and convex if and only if robust duality holds for every linear objective function of the program. In the case of uncertain problems with affinely parameterized data uncertainty, we establish that robust duality is easily satisfied under a Slater type constraint qualification. Consequently, we derive robust forms of the Farkas lemma for systems of uncertain semi-infinite linear inequalities.

Integration of different models in the design of chemical processes: Application to the design of a power plant

With advances in the synthesis and design of chemical processes there is an increasing need for more complex mathematical models with which to screen the alternatives that constitute accurate and reliable process models. Despite the wide availability of sophisticated tools for simulation, optimization and synthesis of chemical processes, the user is frequently interested in using the ‘best available model’. However, in practice, these models are usually little more than a black box with a rigid input–output structure. In this paper we propose to tackle all these models using generalized disjunctive programming to capture the numerical characteristics of each model (in equation form, modular, noisy, etc.) and to deal with each of them according to their individual characteristics. The result is a hybrid modular–equation based approach that allows synthesizing complex processes using different models in a robust and reliable way. The capabilities of the proposed approach are discussed with a case study: the design of a utility system power plant that has been decomposed into its constitutive elements, each treated differently numerically. And finally, numerical results and conclusions are presented.

Mathematical programming model for heat exchanger design through optimization of partial objectives

Mathematical programming can be used for the optimal design of shell-and-tube heat exchangers (STHEs). This paper proposes a mixed integer non-linear programming (MINLP) model for the design of STHEs, following rigorously the standards of the Tubular Exchanger Manufacturers Association (TEMA). Bell–Delaware Method is used for the shell-side calculations. This approach produces a large and non-convex model that cannot be solved to global optimality with the current state of the art solvers. Notwithstanding, it is proposed to perform a sequential optimization approach of partial objective targets through the division of the problem into sets of related equations that are easier to solve. For each one of these problems a heuristic objective function is selected based on the physical behavior of the problem. The global optimal solution of the original problem cannot be ensured even in the case in which each of the sub-problems is solved to global optimality, but at least a very good solution is always guaranteed. Three cases extracted from the literature were studied. The results showed that in all cases the values obtained using the proposed MINLP model containing multiple objective functions improved the values presented in the literature.

La enseñanza de robótica en el Máster en Automática y Robótica mediante un robot modular

Este trabajo muestra cómo se realiza la enseñanza de robótica mediante un robot modular y los resultados educativos obtenidos en el Máster Universitario en Automática y Robótica de la Escuela Politécnica Superior de la Universidad de Alicante. En el artículo se describen los resultados obtenidos con el uso de este robot modular tanto en competencias genéricas como específicas, en las enseñanzas de electrónica, control y programación del Máster. En este artículo se exponen los objetivos de aprendizaje para cada uno de ellos, su aplicación a la enseñanza y los resultados educativos obtenidos. En los resultados del estudio, cabe destacar que el alumno ha mostrado mayor interés y ha fomentado su aprendizaje autónomo. Para ello, el robot modular se construyó con herramientas para fomentar este tipo de enseñanza y aprendizaje, tales como comunicaciones interactivas para monitorizar, cambiar y adaptar diversos parámetros de control y potencia del robot.

Desarrollo de un robot modular para la enseñanza en el Máster en Automática y Robótica

Este trabajo presenta el diseño, construcción y programación de un robot modular para el desarrollo tanto de competencias genéricas como específicas, en las enseñanzas de electrónica, control y programación del Master de Automática y Robótica de la Escuela Politécnica Superior de la Universidad de Alicante. En este trabajo se exponen los diferentes módulos propuestos, así como los objetivos de aprendizaje para cada uno de ellos. Uno de los factores más importantes a destacar en el presente estudio es el posible desarrollo de la creatividad y el aprendizaje autónomo. Para ello, se desarrollará especialmente un módulo de comunicación por bluetooth que servirá para monitorizar, cambiar y adaptar on-line diversos parámetros de control y potencia del robot. Además, dicha herramienta se ha introducido como parte de la metodología en las asignaturas del Máster de Electromecánica y Sistemas de Control Automático. En esta memoria se mostrarán los distintos resultados obtenidos durante y en la finalización de este trabajo.

Comparative study of RPSALG algorithm for convex semi-infinite programming

The Remez penalty and smoothing algorithm (RPSALG) is a unified framework for penalty and smoothing methods for solving min-max convex semi-infinite programing problems, whose convergence was analyzed in a previous paper of three of the authors. In this paper we consider a partial implementation of RPSALG for solving ordinary convex semi-infinite programming problems. Each iteration of RPSALG involves two types of auxiliary optimization problems: the first one consists of obtaining an approximate solution of some discretized convex problem, while the second one requires to solve a non-convex optimization problem involving the parametric constraints as objective function with the parameter as variable. In this paper we tackle the latter problem with a variant of the cutting angle method called ECAM, a global optimization procedure for solving Lipschitz programming problems. We implement different variants of RPSALG which are compared with the unique publicly available SIP solver, NSIPS, on a battery of test problems.

Development and programming of Geophonino: A low cost Arduino-based seismic recorder for vertical geophones

The commercial data acquisition systems used for seismic exploration are usually expensive equipment. In this work, a low cost data acquisition system (Geophonino) has been developed for recording seismic signals from a vertical geophone. The signal goes first through an instrumentation amplifier, INA155, which is suitable for low amplitude signals like the seismic noise, and an anti-aliasing filter based on the MAX7404 switched-capacitor filter. After that, the amplified and filtered signal is digitized and processed by Arduino Due and registered in an SD memory card. Geophonino is configured for continuous registering, where the sampling frequency, the amplitude gain and the registering time are user-defined. The complete prototype is an open source and open hardware system. It has been tested by comparing the registered signals with the ones obtained through different commercial data recording systems and different kind of geophones. The obtained results show good correlation between the tested measurements, presenting Geophonino as a low-cost alternative system for seismic data recording.