Aldo Vecchietti

National Scientific and Technical Research Council | conicet · INGAR Instituto de Desarrollo y Diseño

This paper analyzes the distribution logistics for a retail business that has hundreds of stores located long distances from their warehouses. Given narrow revenue margins, retail companies must optimize the cost of the merchandise delivery to its stores. In general, the structure of the distribution consists of warehouses that concentrate goods wh...

In this work, we propose an iterative framework to solve superstructure design problems, which includes surrogate models, with a custom implementation of the Logic-based Outer- Approximation algorithm (L-bOA). We build surrogate models (SM) using the machine learning software ALAMO exploiting its capability for selecting low- complexity basis funct...

This article presents a mathematical model of the soybean’s supply chain for Argentina where the different stakeholders and the material flows among them are represented. The transport used in this sector are trucks, trains, and river ships. The objective is to analyze the emissions of greenhouse gases (GHG) generated by the transportation in this...

We propose a novel iterative procedure to generate hybrid models (HMs) within an optimization framework to solve design problems. HMs are based on first principle and surrogate models (SMs) and they may represent potential plant units embedded within a superstructure. We generate initial SMs with simple algebraic regression models and refine them b...

In this work, we propose a superstructure optimization approach for the optimal design of an ethylene and propylene coproduction plant. We formulate a superstructure that embeds ethane and propane steam cracking technologies, propane dehydrogenation and olefin metathesis processes. We represent the superstructure with a Generalized Disjunctive Prog...

As project management has become a critical subject in modern-world organisations, Operational Research (OR) needs to incorporate mechanisms to deal with rapid, unplanned changes as well as confusing information and stakeholders with conflicting values. Agile methods are widely used and tested in Software Engineering (SE) to deal with problems of t...

Small and medium organisations (SMO) often need to optimise their operations to improve their effectiveness in a competitive world. Advanced Planning Systems (APS) emerged to provide optimal operations in several areas of an organisation, including production planning and scheduling, logistics, financial, among others. Currently, there is a gap in...

In this work, we develop a mathematical model to make decisions about the optimal scheme and operating conditions of an olefin plant. We formulate a superstructure that includes ethane and propane steam cracking, propane dehydrogenation and olefins metathesis process for the co-production of ethylene and propylene. Furthermore, considering the rele...

The Shortest Path Problem with Forbidden Paths (SPPFP) is a variant of the original shortest path problem, where the constraints come from a set of forbidden arc sequences that cannot be part of any feasible solution. Though this problem is addressed in the academic literature and has numerous applications, there are no open-source implementations...

Operational Research (OR) models usually deal with uncertain, changing requirements. This leads to a continuous process of adapting and reworking the mathematical code. However, there are scarce mechanisms to control its quality. This is essential to Software Engineering (SE), as it enforces the use of Unit Testing: automatically running tests afte...

Los problemas denominados “wicked” (o maliciosos) continúan vigentes para la Investigación Operativa (IO). Esto se debe a que los managers y las organizaciones se enfrentan constantemente a cambios en los requerimientos y ambientes. La Ingeniería de Software (IS) propuso la agilidad para gestionar los proyectos de forma que se permita una rápida y...

The shortest path problem with forbidden paths (SPPFP) is a variant of the original shortest path problem. Given a directed graph 𝐺 = (𝑁, 𝐴), there is also a related set 𝐹 of known forbidden sub-paths in 𝐺. The problem is to find the shortest paths from a source to a destination node, with no paths in the solution contain forbidden sub-path. SPPFP...

The production processes of second generation (2G) ethanol from lignocellulosic materials has been extensively studied in the last decades. In particular, the pretreatment of the raw material has received an important amount of research. This stage has the purpose of decomposing the hemicellulose and lignin walls to improve the yield of glucose on...

First, this dataset contains the documentation of the APS-RA (Advanced Planning Systems Reference Architecture), which is a reference architecture to assist and simplify the development of Advanced Planning Systems (APS). These are specific Decision Support System that automates the optimization of the different organizational process, aiming to pr...

Software Architecture remains a difficult topic to teach. This is because of the problem’s complexity, and the integration of interpersonal and technical skills with knowledge from different areas. This paper presents the introduction of Project-Based Learning (PBL) and Team-Based Learning (TBL) in a Software Architecture undergraduate course. The...

Poster created for the Poster Session of ICEIS 2018, for the paper "Towards an Agile Lifecycle in Operation Research Projects".

In this work, the management of a polyurethane foam plant is tackled through a mixed integer linear programming model that simultaneously solves production and inventory planning problems. The production process considers the foaming stage where large polyurethane blocks are produced as well as the curing step where the blocks are dried. The propos...

Often, Operation Research (OR) interventions focus more on solving a specific problem than addressing the project as a whole. Even more, developers do not acknowledge OR models as systems that are part of an organisation. The lack of a methodology guiding the project complicates the introduction of changes in the model due to alterations in the req...

Resumen Enfocar la Investigación de Operaciones (IO) desde una perspectiva de Ingeniería en Sistemas ha producido múltiples ventajas y técnicas, mayormente conocidas como soft-systems, las cuales han cambiado la perspectiva del análisis y diseño del problema a modelar. Sin embargo, la literatura académica continúa denotando al mantenimiento y usabi...

El proceso de elaboración de té negro es una de las principales actividades económicas en la provincia de Misiones y es una importante fuente de trabajo en la zona centro de la misma. Debido al incremento en los costos de suministro de leña requerida como fuente energética de calefacción, en los últimos años se han llevado a cabo varias iniciativas...

El interés en los procesos de obtención de biocombustibles líquidos se ha incrementado durante las últimas décadas. En la República Argentina se estima que en la actualidad alrededor del 50% de las forestaciones no se aprovechan industrialmente. Por lo tanto, desde un punto de vista estratégico es importante desarrollar procesos que permitan utiliz...

En la República Argentina los residuos de caña de azúcar provenientes de la industria sucro-alcoholera representan el 31% de los residuos disponibles para ser utilizados con fines energéticos. Dicha materia prima, está empezando a ser aprovechada en Brasil para producir etanol de segunda generación (2G) en forma comercial por medio de la hidrólisis...

In this work, the pervaporation-distillation hybrid process is proposed to accomplish the separation of the azeotropic mixture methanol-methyl acetate. First, the separation performance of four membranes of a medium-high flux (Pervap 2256, Pervap 2255-30, PolyAl TypM1 and PolyAn) is analyzed with the aid the pervaporation separation index (PSI). Fo...

Investments in the energy sector on the medium/long term are risky due to the uncertainties having in this sector: price volatility, unclear demands and indeterminate fossil reserve volumes, among others. Decision making tools plays an important role in order to attenuate the effect of uncertainties in the investment by including this aspect in the...

Advanced Planning Systems (APS) are core for many production companies that require the optimization of its operations using applications and tools such as planning, scheduling, logistic, among others. Because of this, process optimization experts are required to develop those models and, therefore, are stakeholders for this system's domain. Since...

A Generalized Disjunctive Programming (GDP) model for the optimal multi-period production planning and stock management is proposed in this work. The formulation is applied to a polyurethane foam manufacturing plant that comprises three stages: a first step that produces pieces with certain characteristics, a second process that involves the locati...

The increasing market competitiveness has put the supply chain (SC) optimization into the focus in the last years. In this context, forest SC needs new investments as well as a new business vision in order to keep profitable and satisfy customers needs and social expectations. The provision of renewable energy sources can be one strategic aspect of...

Resumen Las Arquitecturas de Referencia (AR) proveen lineamientos generales para enmarcar tipos de sistemas. Desde hace unos años, la academia ha generado diversas AR, siempre orientadas a distintos dominios. Un caso particular es el de una AR enfocada en Sistemas de Planeamiento Avanzado (APS). Sin embargo, se necesita evaluar que la definición de...

In the last years, bioethanol production from lignocellulosic materials is receiving more attention from researchers since it is an abundant raw material in certain regions, it is cheaper, does not compete with foods like sugarcane or corn, and can reduce up to 86% of carbon dioxide emissions when compared with gasoline. However, the process econom...

Advanced Planning Systems (APS) are important for production companies that seek the optimization of its operations. However there are gaps between the companies’ needs and its implementation in the Enterprise Systems, such as the lack of a commonly accepted definition, the short insight on its software architecture, and the absence of Software Eng...

Advanced Planning Systems (APS) have become an important tool for manufacturing and production companies that require a specific system to optimize production, logistic, material and human resources, etc. with the goal of improving the economy of the companies and offer a good customer service. An APS must be integrated to the Enterprise's System (...

Tea industry is one of the main activities in the northeast of Argentina. It presents some particularities respect of tea production in other regions of the world, mainly in the high level of automation in tea shoots harvesting. Besides, the factory configurations in terms of the equipment used in tea production are different and it is not clear if...

This paper presents an intelligent agent to analyze the ERP's (Enterprise Resource Planning) system data structure and its compliance on the ANSI/ISA-95 standard. The knowledge base of the agent is generated using the manufacturing categories information provided by mentioned standard. The approach proposes an infrastructure of a knowledge-based ag...

Resumen. Los sistemas de planeamiento han recibido un mayor interés desde que se ha ampliado la utilización de sistemas ERP (Enterprise Resource Planning); sin embargo, esto ha incrementado las diferencias que existen entre la teoría y la práctica del planeamiento y scheduling. Conocidos como APS (Advanced Planning Systems), muchos autores han conc...

This paper proposes a FMIP (fuzzy mixed integer program) to model the procurement process of a manufacturing company which contemplates uncertainty in the delivery of raw materials. The focus of this article lies on the use of fuzzy sets to represent the percentages of failure in the delivery of the amount of materials requested and include it in a...

Fossil fuels have been the main source of energy to produce goods and services. Even today, most countries present an energy matrix based on this non-renewable and contaminant sources. However, energy demand is increasing, reserves will be not available at some point in the future and the extraction and exploration costs will increase substantially...

Los cambios en las organizaciones y la búsqueda de la integración, ha generado una necesidad de estandarizar las estructuras de datos empleadas para compartir información, con el objetivo de aumentar la eficiencia del flujo de información. El estándar ANSI/ISA-95 ha cobrado gran relevancia como un medio para la estandarización y automatización de s...

Fossil sources scarcity and environmental contamination are the major factors that put the energy industry into focus. Considering the lack of accuracy in fossil reserves, we propose an optimization model to plan investments in the Argentinean energy structure taking into account uncertainty in the fossil source availability. Tactical decisions, su...

La marcada tendencia a la globalización y comunicación entre organizaciones, conlleva la necesidad de establecer una base sobre la información a compartir, y estandarizar las estructuras de datos que se utilicen, con el objetivo de mejorar la eficiencia de dicho flujo de información. Desde hace tiempo, el estándar ANSI/ISA-95 ha ido cobrando más re...

En los modelos de muchas aplicaciones industriales en las que se realizan procesos de mezclado surgen frecuentemente términos que incluyen el producto de dos variables continuas. Estos términos, denominados bi-lineales, generan no-convexidades que dificultan la optimización de dichos procesos. En particular el problema de Pooling y sus derivados, s...

This paper presents a mathematical programming model for planning investment in energy sources. The problem formulation considers the use of renewable and not renewable sources and demands, revenues, operation, start-up, and amortization costs of new energy facilities and the amount of reserves of fossil fuels. The objective is the maximization of...

This work proposes a linear disjunctive multiperiod optimization model for planning investments in energy sources considering two objectives, one economical (maximization of the net present value), and the other environmental (minimization of greenhouse gas emissions - GHG). The general goal of this approach is to provide an analysis tool for energ...

An optimization model is proposed to redesign the supply chain of spare part delivery under demand uncertainty from strategic and tactical perspectives in a planning horizon consisting of multiple periods. Long term decisions involve new installations, expansions and elimination of warehouses and factories handling multiple products. It is also con...

La aplicación e implementación de modelos matemáticos tendientes a colaborar con la toma de decisiones no resulta un proceso sencillo y directo: existen diversos factores que dificultan la integración de los modelos matemáticos desarrollados con los sistemas de información empresariales. ERP 2 Optimizer Linkage (E2OL) es un sistema que acopla un mo...

Los sistemas conocidos como Advanced Planning and Scheduling (APS) surgieron con el objetivo de proveer funcionalidades avanzadas en el planeamiento y scheduling, intentando mejorar las capacidades que los ERP (Enterprise Resource Planning) poseen en esa área. Se han realizado muchas investigaciones pertinentes, pero aquellas que realmente lograron...

El proceso de producción de té negro tiene múltiples variantes, cada una con sus respectivas ventajas técnicas y económicas. En este trabajo se propone un modelo matemático para realizar la síntesis del proceso de elaboración del té, teniendo como objetivo la minimización de los costos de inversión y de operación de la planta. En el modelo se inclu...

La aplicación e implementación de modelos matemáticos tendientes a colaborar con la toma de decisiones no resulta un proceso sencillo y directo: existen diversos factores que dificultan la integración de los modelos matemáticos desarrollados con los sistemas de información empresariales. ERP 2 Optimizer Linkage (E2OL) es un sistema que acopla un mo...

In this article, optimization problems with bilinear constraints involving one discrete variable are studied. Several industrial problems present bilinear non-convex constraints which are difficult to solve to global optimality. For this purpose models must be reformulated what in general terms increases the problem size. This article proposes two...

This article studies the supply chain redesign under demand uncertainty over a multi-period planning. We propose an optimization model to solve the problem taking into account strategic and tactical plans. This model is applied to the electric motors industry but it can be easily extended to other supply chains. Long term decisions involve new inst...

An integrated approach that solves the cutting stock problem and scheduling is considered in this article. The main challenging characteristics of this problem are given by its combinatorial nature, as well as the nonconvexities appearing in the formulation. Scheduling decisions are directly affected by cutting patterns and present changeover times...

Uncertainty modeling is a challenging topic in supply chain and operation management. When planning material purchase and stock levels, demand uncertainty could have an important impact on the plan results and its feasibility. Additionally, uncertainty could greatly affect customer satisfaction, inventory costs and company profits. From a modeling...

Generalized disjunctive programming (GDP) is an extension of the disjunctive programming paradigm developed by Balas. The GDP formulation involves Boolean and continuous variables that are specified in algebraic constraints, disjunctions and logic propositions, which is an alternative representation to the traditional algebraic mixed-integer progra...

Optimal supply chain redesign in the electric motor industry Maria Analia Rodriguez, Aldo R. Vecchietti, Iiro Harjunkoski and Ignacio E. Grossmann The integration of supply chain redesign and tactical decisions such as defining inventory levels and how supply chain nodes are connected is a challenging problem that can greatly impact companies' e...

Images recovery by combining low level descriptors and semantic content is a big challenge. In this work we present a three level software architecture implemented in an Object-Relational database that allows the image queries using both descriptions. For the physical level (low-level) MPEG-7 standard descriptors are employed and for the semantic m...

OR-Transformer es una herramienta que asiste en el diseño lógico de una base de datos objeto-relacional. El objetivo de la herramienta es facilitar y asistir al desarrollador de aplicaciones en la tarea de definir los objetos del “schema” de una base de datos. El usuario ingresa el diseño conceptual de datos por medio de un diagrama de clases UML,...

Nowadays it is common to combine low-level and semantic data for image retrieval. The images are stored in databases and computer graphics algorithms are employed to get the pictures. Most of the works consider both aspects separately. In this work, using the capabilities of a commercial ORDBMS a reference architecture was implemented for recoverin...

Supply processes play an important role in customer satisfaction and company costs. The main characteristics of this problem are given by several decisions that follow a hierarchical structure and a very uncertain context, conditioning the success of the solutions proposed. Two significant sources of uncertainty are considered in this work, namely,...

The always increasing energy demand combined with the declining availability of fossil fuels is driving forces for the investigation of renewable energy sources. In this context, bioethanol is considered as one of the most appropriate solutions for short term gasoline substitution. Then, the motivation of this work is to propose a MINLP optimizatio...

In the market there is a wide amount of CASE tools for the design of relational databases. Object-relational database management system (ORDBMS) emerged at the end of the 90's to incorporate the object technology into the relational databases, allowing the treatment of more complex data and relationships than its predecessor. The design for this da...

In this article, a general database infrastructure implemented in an Object-Relational Database Management System for image retrieval is proposed and describe. Semantic and content based image queries can be performed with this application. The infrastructure is structured into three levels: content-based, semantic data and an interface integrating...

This work deals with the inventory, purchase and delivery optimization problem in the supply chain. The formulation of two problems is presented involving several decision levels. The first one optimizes the company inventory and purchase tasks in a medium-term horizon planning, assuming that the total amount purchased is delivered at the beginning...

In this article, an architecture for image retrieval in an Object-Relational Database Management System is proposed. It combines the use of low-level descriptors and semantic metadata for similarity search. The architecture has three levels: content-based, semantic data and an interface integrating them. Several database User Defined Types (UDT) an...

This work addresses the optimization of material inventory management and purchase problems by linking two important players in the supply chain: material suppliers and product manufacturers. The context modeled considers a medium term horizon planning which presents a seasonal demand and a variable restricted capacity from the suppliers. Tradition...

En este artículo se analizan diversos mecanismos que brinda la tecnología Objeto-Relacional (OR) para el almacenamiento de imágenes en una Base de Datos. El objetivo fue estudiar, mediante la implementación de dos ejemplos en Oracle 10g, el comportamiento de la tecnología OR en el almacenamiento, la formulación de consultas, la recuperación de la i...

Supply-chain optimization is a key issue in gainnig competitiveness in today’s economies where buyers and suppliers develop long-term relationships. Final agreements are formalized by signing contracts involving the purchasing of large amounts of materials, taking advantage of economies of scale. Although establishing agreements with suppliers is d...

In the present work, the planning and cutting problem for the corrugated board boxes industries is presented. This problem belongs to the category of the trim-loss problem, which is essential in the paper-converting supply chain management. Bilinear terms in demand and stock constraints, for instance, lead to a non-convex formulation. Two global co...

The development of a disjunctive program solver is described in this paper. First, the implementation of a language compiler needed to formulate discrete decisions thorough disjunctions is presented. The proposed language is implemented as a superset of the commercial mathematical program system solver GAMS. The interactions between both systems ar...

In this paper the cutting stock problem for the corrugated board boxes industry is presented. The problem is solved by means of a two step strategy. First, patterns pre-generation model is formulated which are then used as input in a mathematical MILP model that optimizes the cutting process minimizing the paper trim-loss costs. Several parameters...

The objectives of this paper are to give a brief overview of the code LogMIP and to report numerical experience on a set of test problems. LOGMIP is currently the only code for disjunctive programming, which has implemented the research work done on this area on the last decade. Major motivations in the development of LogMIP have been to facilitate...

Recently, the SQL:2003 standard has been completed by introducing corrections and new capabilities to the SQL:1999. With databases complying with the two standards more complex applications can be developed. For database design, in the literature it is possible to find articles about the mapping steps from an entity-relationship model and from UML...

This article presents several synthesis and design optimization problems in process system engineering involving hierarchical decisions modeled by means of nested disjunctions. It does not exists an algorithm to solve problems formulated with those type of disjunctions, therefore it is needed a transformation of nested disjunctions into a formulati...

This paper presents a novel solution strategy for the synthesis of multiproduct and multihost protein production processes. There are several possible hosts that may express each of the products, and different downstream processing separation and purification tasks are needed, which in part depend on the host selection. Moreover, alternative unit o...

This article presents a model for the synthesis of a biotechnological process in which a set of biotechnological products must be elaborated. For each of these products, there is a set of hosts that can be used for production. According to the host selected for each product, there is a different set of stages involved in the process. Furthermore, t...

The retrofit problem for multiproduct batch plants deals with the modification of the original structure of the plant to meet new production conditions such as the introduction of new products, a new supply pattern, etc. For this problem, a disjunctive model is presented, which takes into consideration every usual alternative about the configuratio...

Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 How to Run a Model with GAMS/DICOPT . . . . . . . . . . . . . . . . . . . . . . . 2 4 Overview of DICOPT . . . . . . . . . . . . . . . ....

This paper addresses the relaxations in alternative models for disjunctions, big-M and convex hull model, in order to develop guidelines and insights when formulating Mixed-Integer Non-Linear Programming (MINLP), Generalized Disjunctive Programming (GDP), or hybrid models. Characterization and properties are presented for various types of disjuncti...

DICOPT is a program for solving mixed-integer nonlinear programming (MINLP) problems that involve linear binary or integer variables and linear and nonlinear continuous variables. While the modeling and solution of these MINLP optimization problems has not yet reached the stage of maturity and reliability as linear, integer or non-linear programmin...

In this work we propose a model that simultaneously optimizes the process variables and the structure of a multiproduct batch plant for the production of recombinant proteins. The complete model includes process performance models for the unit stages and a posynomial representation for the multiproduct batch plant. Although the constant time and si...

This work reports findings about the role of process variables in the design of multiproduct batch plants. Unlike co ntinuo us pro cesses, batch pro cesses are subject to size and time constraints which depend on the structure of the plant: the number of units at each stage and the pro visio n of intermediate storag e. We used simple process perfor...

In this work, we propose optimization approaches that make use of process information for the design of multiproduct batch plants. First, we develop an optimization model for designing multiproduct batch plants. The plant consists of several parallel stages, which can work either in phase or out-of-phase. Processing times and size factors for each...

This paper describes a number of key modeling issues for the development of tools for solving nonlinear discrete/continuous problems where logic/disjunctive constraints are included in the formulation. A generalized hybrid representation of these problems is presented. A comparison between Constraint logic programming (CLP) and generalized disjunct...

Process performance models for a multiproduct batch protein plant are used to exploit alternative strategies in the optimization of both the process variables and the structure of the plant. Simple process performance models are used to describe the unit operations, which renders explicit expressions for the size and time factor model in the design...

In this work we propose an optimization model for the design of a biotechnological multiproduct batch plant. A first level of detail posynomial model is constructed for each unit, as well as decisions regarding the structural optimization of the plant. A particular feature of this model is that it contains composite units in which semicontinuous it...

Discrete-continuous non-linear optimization models are frequently used to formulate problems in process system engineering. Major modeling alternatives and solution algorithms include generalized disjunctive programming and mixed integer non-linear programming (MINLP). Both have advantages and drawbacks depending on the problem they are dealing wit...

Optimal allocation of intermediate storage tanks is an important issue in a batch plant to reduce its cost. In this work the design of multiproduct batch plant is analyzed. The proposed model considers simultaneously the possibility of having parallel units and intermediate storage tanks. The location of the storage tanks can be variable for each p...

Discrete-continuous non-linear optimization models are frequently used to formulate problems in Process System Engineering. Major modeling alternatives and solution algorithms include generalized disjunctive programming and MINLP. Both have advantages and drawbacks depending on the problem they are dealing with. In this work, we describe the theory...

A distillation train of pure iso-propanol (99.99%) has been studied to determine new operating conditions, in order to attain an increase in throughput without changes in geometrical parameters. A methodology to obtain the operating pressure for the new production rate is analyzed.The Kister and Doig (1977, 1979) criterion (feed capacity vs operati...

The data-handling capabilities of a commercial data base management system (DBMS) are used to control the information flow in a sequential modular steady-state process simulator. Thus, a new structure for the execution of this type of simulators is presented, in which executable program using a rigid agenda from a command file are called sequential...

A system to predict physicochemical and transport properties for a steady state process simulator is presented. The data handling capabilities of the Physicochemical Properties Package are managed by a Data Base Management System. The structure of the physicochemical package is such that it allows access from the simulator as well as from external...

A network type Data Base Management System is used to support the data structure of a modular-sequential, steady state process simulator. The DBMS of a standard CODASYL type is based on the definition of records and the set relationships between an owner and a member record. The structure defined, or SCHEMA, responds to the way data is stored and u...

The information handling capability of Data Base Management Programs, together with heat and mass balances programs, has given rise to a new generation of chemical processes simulators. This new generation combines versatility and reliability in the handling of information, with software versions which are both powerful and precise. SIMBAD/INGAR is...