Luiz Satoru Ochi

Fluminense Federal University | UFF · Departamento de Ciência da Computação (DCC)

This paper deals with Unmanned Aerial Vehicle (UAV) routing in dynamic grid scenarios with limited battery autonomy and multiple charging stations. Inspired by a multi-criteria view of real systems, we consider different objective functions, while respecting the navigation over forbidden areas and also a real-time flight autonomy. A multi-objective...

Avoiding conflicting elements is a natural constraint that appears in several graph problems making them more challenging and close to real applications. Minimum Conflict-Free Spanning Tree (MCFST) is a variant of the classic Minimum Spanning Tree (MST) problem, where we are asked to find (if any) the spanning tree avoiding pairs of conflicting edg...

Para uma cidade ser classificada como "inteligente", ela precisa ter sensores espalhados por ela. A disseminação de dados em uma rede de sensores é um dos desafios que deve ser superado. Em particular, um problema de broadcasting é o WEIGHED MINIMUM BROADCAST TIME (WMBT). O WMBT é um problema de disseminação de dados cujo objetivo é encontrar um es...

Este artigo trata do roteamento de Veículos Aéreos Não Tripulados (VANT) em cenários dinâmicos de rede com autonomia de bateria limitada e múltiplas estações de carregamento. O problema é inspirado em restrições do mundo real, especialmente projetado para superar os desafios de um alcance limitado de condução de veículos. Considera-se uma variante...

O problema de roteamento híbrido com veículo-drone para serviço de coleta e entrega (HVDRP) modela diversas aplicações industriais de logística em cidades inteligentes, como serviços de monitoramento e de transporte de pacotes. No HVDRP, um veículo é equipado com vários drones para servir clientes com demandas de coleta e entrega. O veículo transit...

O lixo eletrônico (e-lixo) é um dos problemas socioambientais que mais tem chamado a atenção da sociedade devido ao seu crescente volume, somado ao descarte inadequado. Desse modo, faz-se necessário que os Resíduos de Equipamentos Elétricos e Eletrônicos (REEE) tenham uma gestão adequada que minimize o problema de logística reversa na sua coleta e...

O tema de Cidades & Regiões Inteligentes possui diversos segmentos de extrema importância, dentre eles a de Logística Reversa & Sistemas Inteligentes de Transporte. Neste contexto destacamos o Problema de Roteamento de Veículos (PRV) que se torna cada vez mais relevante, com o aumento das compras online (e-commerce). Algumas das variantes mais impo...

This thesis investigates several aspects of computational problems related to circuits and neighborhood exploration. Supported by a vast literature, we explore notable trends in algorithms, optimization, and computational complexity; and we provide some results for each topic discussed. The thesis' contributions are organized into four projects: (i...

Cyber-physical systems (CPS) are multi-layer complex systems that form the basis for the world’s critical infrastructure and, thus, have a significant impact on human lives. In recent years, the increasing demand for connectivity in CPS has brought attention to the issue of cyber security. Aside from traditional information systems threats, CPS fac...

Unmanned Aerial Vehicles are becoming a common technology used on smart cities and smart regions, thus requiring optimization of its routes with crucial importance. In this innovative work, six objective functions are considered in order to provide sets of non-dominated solutions, composed of routes with different characteristics. Realistic constra...

Neighborhood search techniques are often employed to deal with combinatorial optimization problems. Previous works got good results in applying a novel neighborhood search methodology called Multi Improvement (MI). First and best improvement are classical approaches for neighborhood exploration, while the MI has emerged due to the advance of new pa...

A natural constraint in real-world applications is to avoid conflicting elements in the solution of problems. Given an undirected graph G=(V,E) where each edge e∈E has a positive integer weight ω(e), and a conflict graph G^=(V^,E^) such that V^⊆E and each edge e^=(e1,e2)∈E^ represents a conflict between two edges e1,e2∈E, in the Minimum Conflict-Fr...

Measures of circuit complexity are usually analyzed to ensure the computation of Boolean functions with economy and efficiency. One of these measures is the energy complexity, which is related to the number of gates that output true in a circuit for an assignment. The idea behind energy complexity comes from the counting of ‘firing’ neurons in a na...

The Traveling Salesperson Problem with Hotel Selection (TSPHS) corresponds to a variant of the classic Traveling Salesman Problem (TSP) where the salesperson must establish a route in order to visit and attend all customers and return to the point of origin. At the end of each working day, if they had not attended all customers, the salesperson mus...

Given a bipartite graph G=(V1,V2,E), a biclique of G is a complete bipartite subgraph of G, and a biclique partitioning of G is a set A⊆E such that the bipartite graph G′=(V1,V2,A) is a vertex-disjoint union of bicliques. The biclique partitioning problem (BPP) consists of, given a complete bipartite graph G=(V1,V2,E) with edge weights we∈R for all...

Cyber-Physical Systems (CPS) are the basis for the world’s critical infrastructure and, thus, have the potential to significantly impact human lives in the near future. In recent years, there has been an increasing demand for connectivity in CPS, which has brought to attention the issue of cybersecurity. Aside from traditional information systems t...

The dissemination of microdata by public institutions, especially National Statistical Offices (NSOs), and data sharing between public and private organizations and the academia are of undeniable importance today. However, very important ethical and legal aspects related to privacy protection, whether for an individual or a company, often restrict...

Companies have given close attention to new ways to reduce operational costs, and a way to achieve this point is focusing on optimizing the planning of routes. A variant of the traveling salesperson problem (TSP), called the traveling salesperson problem with hotel selection, was introduced in the last years. Herein, the salesperson needs to visit...

The Hybrid Vehicle drone Routing Problem (HVDRP) was recently introduced as an extension of the classic Vehicle Routing Problem (VRP). In this version, one vehicle is equipped with multiple drones to serve customers with demands for pick-up and delivery. The vehicle travels between stations that serve as parking locations to dispatch drones to atte...

Heuristics denote a powerful concept, covering a wide range of computational, economic, and psychological sciences , as the ability to handle challenging problems with minimal resources. From a computational perspective, heuristics are commonly used in decision making-when vast amounts of information are available in complex environments-or even wh...

Cyber-Physical Systems (CPS) will form the basis for the world’s critical infrastructure and, thus, have the potential to significantly impact human lives in the near future. In recent years, there has been an increasing demand for connectivity in CPS, which has brought to attention the issue of cyber security. Aside from traditional information sy...

This paper deals with Unmanned Aerial Vehicle (UAV) routing in dynamic grid scenarios with limited battery autonomy and multiple charging stations. The problem is inspired by real-world constraints, specially designed for overcoming challenges of a limited vehicle driving range. Recently, these kinds of vehicles have started to be used for deliveri...

This paper deals with the Flooding Problem on graphs. This problem consists in finding the shortest sequence of flooding moves that turns a colored graph into a monochromatic one. The problem has applications in some areas as disease propagation, for example. Three metaheuristics versions are proposed and compared with the literature results. A new...

Dados um grafo não direcionado com pesos nas arestas e um conjunto de pares de arestas conflitantes, a Árvore de Geradora Mı́nima com Restrições de Conflito (AGMRC) consiste em encontrar árvore geradora com no máximo uma aresta de cada par conflitante e custo mı́nimo. O problema é N P-difı́cil e foi introduzido recentemente na literatura. Este arti...

OptFrame is a C++ framework that facilitates the implementation of metaheuristics for optimization. This year marks the 10th anniversary of the publication of OptFrame in SBPO XLII. In the most recent 4.0 version, the tool has new functionalities using the latest capabilities of modern C++ standards, such as coroutines and closures. OptFrame has be...

A usual way to collect data in a Wireless Sensor Network (WSN) is by the support of a special agent, called data mule, that moves between sensor nodes and performs all communication between them. In this work, the focus is on the construction of the route that the data mule must follow to serve all nodes in the WSN. This paper deals with the case w...

Resumo: Apresentamos neste trabalho um novo método para otimização global intitulado Al-goritmo de Formação Social de Opinião (Social Opinion Formation Algorithm-SOFiA), inspi-rado pela dinâmica social do processo de formação de opinião. O algoritmó e avaliado através de um estudo comparativo envolvendo dois outros algoritmos bem estabelecidos na l...

Resumo: Apresentamos neste trabalho um novo método para otimização global intitulado Al-goritmo de Formação Social de Opinião (Social Opinion Formation Algorithm-SOFiA), inspi-rado pela dinâmica social do processo de formação de opinião. O algoritmó e avaliado através de um estudo comparativo envolvendo dois outros algoritmos bem estabelecidos na l...

The Traveling Salesperson Problem with Hotel Selection (TSPHS) is a novel variant of the classical Traveling Salesperson Problem. In this variant, the main objective is to minimize the number of trips and total traveled time. This problem is found in real scenarios like delivery of products by electric vehicles that need to be recharged along a tou...

A global trend has been motivating programmers, investors, and the academia to go towards decentralized systems. Besides providing efficient solutions for complex problems faced in our daily life, these peer-to-peer communication protocols have been promoting greater freedom and transparency. In this paper, we point out open fields for researching,...

Let G = (V, E, L) be an edge-labeled graph such that V is the set of vertices, E is the set of edges, L is the set of labels (colors) and each edge e \in E has a label l(e) associated; The goal of the minimum labeling global cut problem (MLGCP) is to find a subset L \subseteq L of labels such that G = (V, E , L\L ) is not connected and |L| is minim...

We consider a family of rich vehicle routing problems (RVRP) which have the particularity to combine a heterogeneous fleet with other attributes, such as backhauls, multiple depots, split deliveries, site dependency, open routes, duration limits, and time windows. To efficiently solve these problems, we propose a hybrid metaheuristic which combines...

This paper extends some explanations about the convergence of a type of Evolution Strategies guided by Neighborhood Structures, the Neighborhood Guided Evolution Strategies. Different well-known Neighborhood Structures commonly applied to Vehicle Routing Problems are used to highlight the evolution of the move operators during the evolutionary proc...

Cluster Analysis is a multivariate method to handle real problems associated with several fields. This area combines several methods of unsupervised classification, which can be applied in order to identify groups in a data set. The Clustering Problems are classified as NP-Hard and, in order to obtain such classification, the number of groups k may...

An edge-labeled graph (ELG) is a graph in which each edge has a label associated. Given G, an ELG, the minimum labeling spanning tree problem (MLSTP) is an NP-hard problem that consists in finding a spanning tree in G by using a minimum number of labels. The MLSTP has applications in areas such as computer networks, multimodal transportation networ...

We propose an iterated local search based on several classes of local and large neighborhoods for the bin packing problem with conflicts. This problem, which combines the characteristics of both bin packing and vertex coloring, arises in various application contexts such as logistics and transportation, timetabling, and resource allocation for clou...

The Green Vehicle Routing and Scheduling Problem (GVRSP) aims to minimize carbon Dioxide Emissions (CO2) in logistics systems through better planning of deliveries made by a fleet of vehicles. In this paper, the GVRSP considers heterogeneous vehicles, time-varying traffic congestion, capacity constraints and the delivery can be fractionated. The GV...

The minimum labeling spanning tree problem (MLSTP) is a combinatorial optimization problem that consists in finding a spanning tree in a simple graph G, in which each edge has one label, by using a minimum number of labels. It is an NP-hard problem that was introduced by Chang and Leu (Inf Process Lett 63(5):277–282, 1997. https://doi.org/10.1016/S...

Block-modeling is a framework to describe a social network as a small structure. We propose here a Neighborhood Exploration Approach with Multi-start for tackling the Extend Generalized Block-modeling. The Extend Generalized Blockmodeling is the first and most complete model approach: it allows to analyze networks without any a priory knowledge abo...

A usual way to collect data in a Wireless Sensor Network (WSN) is by the support of a special agent, called data mule, that moves among sensor nodes and performs all communication between them. This article dealt with the Data Mule Scheduling Problem (DMSP), where in addition to the data mule routing, it is necessary to plan the speed that this dat...

Let G=(V,E,L) be an edge-labeled graph. Let V be the set of vertices of G, E the set of edges, L the set of labels (colors) such that each edge e∈E has an associated label L(e). The goal of the minimum labeling global cut problem (MLGCP) is to find a subset L′⊆L of labels such that G′=(V,E′,L\L′) is not connected and |L′| is minimized. In this work...

We consider a family of Rich Vehicle Routing Problems (RVRP) which have the particularity to combine a heterogeneous fleet with other attributes, such as backhauls, multiple depots, split deliveries, site dependency, open routes, duration limits, and time windows. To efficiently solve these problems, we propose a hybrid metaheuristic which combines...

We consider the multi-vehicle one-to-one pickup and delivery problem with split loads, a NP-hard problem linked with a variety of applications for bulk product transportation, bike-sharing systems and inventory re-balancing. This problem is notoriously difficult due to the interaction of two challenging vehicle routing attributes, "pickups and deli...

The NP-hard Bicluster Editing Problem (BEP) consists of editing a minimum number of edges of an input bipartite graph G in order to transform it into a vertex-disjoint union of complete bipartite subgraphs. Editing an edge consists of either adding it to the graph or deleting it from the graph. Applications of the BEP include data mining and analys...

Given a graph G and a pair s,t in V(G), where each edge e has a weight t(e) and each vertex v has a value p(v) such that t(e) represent a transportation time and p(v) a prize collecting. Prize Collecting Path (PCP) consists of finding a (s,t)-path that minimizes the total transportation time minus the total prize of nodes in such path. PCP is at co...

Optimization tasks are often complex, CPU-time consuming and usually deal with finding the best (or good enough) solution among alternatives for a given problem. Parallel metaheuristics have been used in many real-world and scientific applications to efficiently solve these kind of problems. Local Search (LS) is an essential component for some meta...

We propose an iterated local search based on several classes of local and large neighborhoods for the bin packing problem with conflicts. This problem, which combines the characteristics of both bin packing and vertex coloring, arises in various application contexts such as logistics and transportation, timetabling, and resource allocation for clou...

Among the methods to deal with optimization tasks, parallel metaheuristics have been used in many real-world and scientific applications to efficiently solve these kind of problems. This paper presents a novel Multi Improvement strategy for dealing with the Minimum Latency Problem (MLP), an extension the classic Traveling Salesman Problem. This str...

This paper introduces an Unmanned Aerial Vehicle (UAV) heterogeneous fleet routing problem, dealing with vehicles limited autonomy by considering multiple charging stations and respecting operational requirements. A green routing problem is designed for overcoming difficulties that exist as a result of limited vehicle driving range. Due to the larg...

As the new generation of smart sensors is evolving towards high sampling acquisitions systems, the amount of information to be handled by learning algorithms has been increasing. The Graphics Processing Unit (GPU) architecture provides a greener alternative with low energy consumption for mining big data, bringing the power of thousands of processi...

In this paper (a substantial extension of the short version presented at REM2016 on April 19–21, Maldives [1]), multi-objective power dispatching is discussed in the scope of microgrids located in smart cities. The proposed system considers the use of Plug-in Electric Vehicle (PEV) and Unmanned Aerial Vehicle (UAV) as storage units. The problem inv...

This paper tackles a Traveling Salesman Problem variant called Traveling Car Renter Problem, where one car renter desires to travel among cities using a rented vehicle. Basically, the car renter has two options when he/she arrives in a city: to return the vehicle and rent another one or to keep the same car until the next city. Every time a car is...

We study a multivehicle inventory routing problem (MIRP) in which supplier delivers one type of product along a finite planning horizon, using a homogeneous fleet of vehicles. The main objective is to minimize the total cost of storage and transportation. In order to solve MIRP, we propose an algorithm based on iterated local search (ILS) metaheuri...

The bicluster editing problem (BEP) consists of editing (adding or removing) the edges of a bipartite graph G in order to transform it into a vertex-disjoint union of complete bipartite subgraphs, in such a way that the sum of the weights of the edited edges is minimum. In this paper, we propose five parallel strategies for the implementation of a...