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Publications

2019

Capacitated Vehicle Routing Problem with Heterogeneous Fixed Proprietary Fleet and Outsourcing Delivery—A Clustering-Based Approach

Authors
Bertoluci, R; Ramos, AG; Lopes, M; Bastos, J;

Publication
Springer Proceedings in Mathematics and Statistics

Abstract
This paper describes a solution method that was created with the objective of obtaining a more efficient finished goods distribution process for a food industry company. The finished goods distribution process involves the use of the companys own fleet to serve a specific group of customers, and the use of outsourcing transportation services that can make direct and transshipment customer deliveries. The complexity of the problem is due to the need to decide which customers should be served by each of the outsourcing transportation services, direct or transshipment, and to find cost efficient solutions for the multiple vehicle routing problems created. First, an original clustering method consisting of a logical division of the customer orders using a delivery ratio based on the transportation unit cost, distance and order weight, is used to define customer clusters by service type. Then, an exact method based on a mixed integer programming model, is used to obtain optimal vehicle routing solutions, for each cluster created. The solution method for the company real instances, proved able to reach the initial proposed objectives and obtain promising results that suggest an average reduction of 34% for the operational costs, when compared to the current distribution model of the company. © 2019, Springer Nature Switzerland AG.

2019

Humidity sensor based on optical fiber coated with agarose gel

Authors
Novais, S; Ferreira, MS; Pinto, JL;

Publication
OPTICAL SENSORS 2019

Abstract
A reflective fiber optic sensor based on multimode interference for the measurement of relative humidity (RH) is proposed and experimentally demonstrated. The proposed probe is fabricated by fusion-splicing, approximately 30 mm long coreless fiber section to a single mode fiber. A hydrophilic agarose gel is coated on the coreless fiber, using the dip coating technique. When the incident light comes from the SMF to the CSF, the high-order modes are excited and propagate within the CSF. These excited modes interfere with one another as they propagate along whole CSF length, giving rise to a multimode interference (MMI). Since the effective refractive index of the agarose gel changes with the ambient relative humidity, as the environmental refractive index changes, the propagation constants for each guided mode within the CSF will change too, which leads to shifts in the output spectra. The proposed sensor has a great potential in real time RH monitoring, exhibiting a large range of operation with good stability. For RH variations in the range between 60 %RH and 98.5 %RH, the sensor presents a maximum sensitivity of 44.2 pm/%RH, and taking in consideration the interrogation system, a resolution of 1.1%RH is acquired. This sensor can be of interest for applications where a control of high levels of relative humidity is required.

2019

Application of the A3 methodology for the improvement of an assembly line

Authors
Pereira J.; Silva F.J.G.; Bastos J.A.; Ferreira L.P.; Matias J.C.O.;

Publication
Procedia Manufacturing

Abstract
In an increasingly and globally competitive industry like the automotive sector, the continuous improvement of processes assumes a key role in the enhancement of effectiveness and efficiency. In line with this philosophy, the study undertaken of the work method and its inherent activities has pointed to time measurement as a gemba support tool of great potential in the optimization of the production process and the elimination of mudas. The present case study relates to the improvement of productivity of an assembly line dedicated to the manufacture of brake cables for the automotive industry. The application of the A3 methodology to this improvement project aims to monitor the evolution of key indicators as productivity per hour and the Overall Equipment Effectiveness (OEE) of the assembly line, to define the different improvement actions to be executed, and to achieve the defined target, and to validate the results of its implementation. The measurement of the different activities of the assembly line allowed to identify the major wastes (of material movements, operator movements, among others.) and to identify the most critical workstations that contribute for the unbalancing of the assembly line. The solutions implemented allowed to increase the productivity by 49% and, as a consequence, reduce the cycle time in 33%. The rearrangement and improvement of operations allowed also to increase the efficiency of the assembly line balancing in 11%. As the A3 methodology assumed a key role for this project, allowing the monitoring of the effectiveness of the different improvement actions implemented, it was standardized so that it could be applied to other improvement projects.

2019

An Adaptive Velocity Obstacle Avoidance Algorithm for Autonomous Surface Vehicles

Authors
Campos, DF; Matos, A; Pinto, AM;

Publication
2019 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS)

Abstract
This paper presents a new algorithm for a real-time obstacle avoidance for autonomous surface vehicles (ASV) that is capable of undertaking preemptive actions in complex and challenging scenarios. The algorithm is called adaptive velocity obstacle avoidance (AVOA) and takes into consideration the kinematic and dynamic constraints of autonomous vessels along with a protective zone concept to determine the safe crossing distance to obstacles. A configuration space that includes both the position and velocity of static or dynamic elements within the field-of-view of the ASV is supporting a particle swarm optimization procedure that minimizes the risk of harm and the deviation towards a predefined course while generating a navigation path with capabilities to prevent potential collisions. Extensive experiments demonstrate the ability of AVOA to select a velocity estimative for ASVs that originates a smoother, safer and, at least, two times more effective collision-free path when compared to existing techniques.

2019

Os avatares Maria e João: tutores virtuais na plataforma e-learning da Universidade Aberta

Authors
Marcos, Adérito; Carvalho, Elizabeth; Martinho, Carlos; Cláudio, Ana Paula; Carmo, Maria Beatriz; Rocio, Vitor;

Publication
Inovar para a qualidade na educação digital

Abstract
Este artigo apresenta reflexões seminais acerca da utilização de tutores virtuais no sistema de e-learning da Universidade Aberta. O tutor virtual é uma analogia do tutor humano, adota uma interface antropomórfica com características emocionais, comumente denominado de avatar, que integra inteligência artificial e pode constituir uma abordagem interessante, tanto para o professor como para os estudantes, se se perspetivar o futuro dos ambientes típicos de ensino e educação a distância online e em rede e a crescente massificação da individualização do acompanhamento do estudante. Embora atraente de muitas formas, especialmente quando se leva em linha de conta a redução da carga da interação e do apoio que um professor (humano) deve fornecer nesses ambientes, várias questões se colocam visando a plena e efetiva integração de avatares como artefactos de mediação da tutoria virtual. Este artigo fornece um conjunto de perspetivas iniciais sobre este desafio, introduzindo o estado da arte no campo, enquanto apresenta alguns desenvolvimentos recentes e em experimentação na Universidade Aberta pela instanciação de dois avatares – a Maria e o João.;This article presents seminal reflections on the use of virtual tutors in the Aberta University e-learning system. The virtual tutor is an analogy of the human tutor, adopting an anthropomorphic interface with emotional characteristics, commonly called an avatar, which integrates artificial intelligence, and can be an interesting approach for both the teacher and the students, if the future of environments typical of online and networked distance learning and education, and the increasing massification of the individualization of student follow-up. Although attractive in many ways, especially when one takes into account the reduction of the interaction load and the support that a (human) teacher must provide in these environments, several questions are posed for the full and effective integration of avatars as mediation artifacts of virtual tutoring. This article provides a set of initial perspectives on this challenge, introducing the state of the art in the field, while presenting some recent developments and experimentation at the Aberta University by the instantiation of two avatars - Mary and John.

2019

Are Millennials Ready for the Internet of Things?

Authors
Barbosa, B; Filipe, S; Santos, CA; Simões, D;

Publication
Smart Marketing With the Internet of Things - Advances in Marketing, Customer Relationship Management, and E-Services

Abstract
A lot has been said about the digital natives and their natural way of integrating the internet in their daily activities. Millennials have been considered a unique segment of consumers by researchers and practitioners alike, due to their ability and propensity to adopt and adapt new media to their daily routine. Although it is expectable that they are particularly keen on embracing IoT, extant literature is scarce on their views on the adoption of IoT to their home, work, and leisure activities. In this chapter, the authors analyze the potential of the millennial segment to IoT products and services. Results of a qualitative study with Portuguese consumers are included and provide interesting cues to marketers working with IoT offers.

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