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Conference Paper
Sallem, A., P. Pereira, M. Fakhfakh, and H. Fino, "A Multi-objective Simulation Based Tool: Application to the Design of High Performance LC-VCOs", Technological Innovation for the Internet of Things, vol. 394, Portugal, Springer Berlin Heidelberg, pp. 459-468, 2013. Abstract

The continuing size reduction of electronic devices imposes design challenges to optimize the performances of modern electronic systems, such as: wireless services, telecom and mobile computing. Fortunately, those design challenges can be overcome thanks to the development of Electronic Design Automation (EDA) tools. In the analog, mixed signal and radio-frequency (AMS/RF) domains, circuit optimization tools have demonstrated their usefulness in addressing design problems taking into account downscaling technological aspects. Recent advances in EDA have shown that the simulation-based sizing technique is a very interesting solution to the ‘complex’ modelling task in the circuit design optimization problem. In this paper we propose a multi-objective simulation-based optimization tool. A CMOS LC-VCO circuit is presented to show the viability of this tool. The tool is used to generate the Pareto front linking two conflicting objectives, namely the VCO Phase Noise and Power Consumption. The accuracy of the results is checked against HSPICE/RF simulations.

Martins, J. F., P. Pereira, A. J. Pires, and V. F. Pires, "A new teaching tool to enhance power quality assessment", Industrial Electronics Society, IECON 2015 - 41st Annual Conference of the IEEE, Yokohama, Japan, IEEE-IES, pp. 004158-004162, 9-12 Nov., 2015. Abstract

The study and assessment of Power Quality issues is nowadays a very important subject, particularly regarding Cyber-physical and Industrial Agents based systems, which are extremely sensitive to Power Quality disturbances. Giving students or engineers practical experience in this field requires a large investment from teaching institutions. This paper presents a laboratory device that emulates Power Quality disturbances in order to provide the required experimental expertize in the subject. It addresses limiting aspects such as harmonic distortion, flicker, sags, swells and transients. The developed system presents a good opportunity for technicians, even without deep knowledge on the field of power quality, to learn basic principles and be able to identify Power Quality events. Since the system is based on real data, represents a valuable approach giving trainees practical knowledge on the field.

Pereira, P., H. Fino, F. Coito, and M. Ventim-Neves, "Optimization-Based Design of Nano-CMOS LC-VCOs", Doctoral Conference on Computing, Electrical and Industrial Systems, DoCEIS 2012, vol. 372, Costa de Caparica - Portugal, Springer Boston, pp. 453-464, 2012. Abstract

This paper introduces a variability-aware methodology for the design of LC-VCOs in Nano-CMOS technologies. The complexity of the design as well as the necessity for having an environment offering the possibility for exploring design trade-offs has led to the development of design methodologies based multi-objective optimization procedures yielding the generation of Pareto-optimal surfaces. The efficiency of the process is granted by using analytical models for both passive and active devices. Although physics-based analytical expressions have been proposed for the evaluation of the lumped elements, the variability of the process parameters is usually ignored due to the difficulty to formalize it into an optimization performance index. The usually adopted methodology of considering only optimum solutions for the Pareto surface, may lead to pruning quasi-optimal solutions that may prove to be better, should their sensitivity to process parameter variation be accounted for. In this work we propose starting by generating an extended Pareto surface where both optimum and quasi-optimum solutions are considered. Finally information on the sensitivity to process parameter variations, is used for electing the best design solution.

Cardoso, T., P. Pereira, V. Fernao Pires, and J. F. Martins, "Power quality and long life education", Industrial Electronics (ISIE), 2014 IEEE 23rd International Symposium on, Istanbul - Turkey, pp. 2224 - 2228, 2014/06. Abstract

This paper presents a remote laboratory linked with mobile devices for real data analysis on the field of power quality. A global system was developed from the power quality analyzer into the human machine interface devoted to the m-learning system. This m-learning system is intended to be used in a long life learning perspective. The developed remote laboratory is a good opportunity for people, even without deep knowledge on the field, to learn power quality principles in an applied way. Since the system is based on real data, is a good approach to give trainees practical knowledge on the field.

Pereira, P., F. Coito, and H. Fino, "PSO-Based Design of RF Integrated Inductor", Doctoral Conference on Computing, Electrical and Industrial Systems, DoCEIS 2012, vol. 372, Costa de Caparica - Portugal, Springer Boston, pp. 475-482, 2012. Abstract

This paper addresses an optimization-based approach for the design of RF integrated inductors. The methodology presented deals with the complexity of the design problem by formulating it as a multi-objective optimization. The multi-modal nature of the underlying functions combined with the need to be able to explore design trade-offs leads to the use of niching methods. This allows exploring not only the best trade-off solutions lying on the Pareto-optimum surface but also the quasi-optimum solutions that would be otherwise discarded. In this paper we take advantage of the niching properties of lbest PSO algorithm using ring topology to devise a simple optimizer able to find the local-optima. For the efficiency of the process analytical models are used for the passive/active devices. In spite the use of physics-based analytical expressions for the evaluation of the lumped elements, the variability of the process parameters is ignored in the optimization stage due to the significant computational burden it involves. Thus in the final stage both the Pareto-optimum solutions and the quasi-optimum solutions are evaluated with respect to the sensitivity to process parameter variations.

Pereira, P., H. Fino, and M. Ventim-Neves, "RF Varactor Design Based on Evolutionary Algorithms", Mixed Design of Integrated Circuits and Systems (MIXDES), 2012 Proceedings of the 19th International Conference, Warsaw, Poland, pp. 277 -282, may, 2012. Abstract

This paper introduces an optimization methodology for the design of RF varactors. The characterization of the varactor behaviour is supported by a set of equations based on technological parameters, granting the accuracy of the results, as well as the adaptability of the model to any technology. The varactor design is achieved through the implementation of a Genetic Algorithms (GA) optimization methodology, which is able to deal with continuous and/or discrete variables, making possible to suit both technological and layout constraints. A set of working examples for UMC130 technology are addressed. The results presented, spotlight the potential of varactor analytical model, combined with a GA optimization procedure, when integrated in optimization design tools. The accuracy of the results is checked against HSPICE simulator.

Marouani, H., A. Sallem, M. Chaoui, P. Pereira, and N. Masmoudi, "A Robustness Study of Metaheuristics to the Optimal Design of RF Integrated Inductors", 2018 15th International Multi-Conference on Systems, Signals Devices (SSD), pp. 1459-1464, March, 2018. Abstract

In this paper, three metaheuristics are investigated to optimize RF Integrated Inductors; namely Differential Evolution (DE) from the field of evolutionary computation, Gravitational Search Algorithm (GSA) based on the law of gravity and mass interactions and Particle Swarm Optimization (PSO) inspired by swarm behaviors in nature. A particular interest is given to the optimization of RF Integrated Inductors. Performances in terms of optimum quality and computing time of the metaheuristics are checked via three test functions and one application that consist of optimizing performances of characterize integrated inductors based on the double$π$-model.

Amorim, M., A. Mar, F. Monteiro, S. Sylaiou, P. Pereira, and J. Martins, "Smart Tourism Routes Based on Real Time Data and Evolutionary Algorithms", Digital Heritage. Progress in Cultural Heritage: Documentation, Preservation, and Protection, Cham, Springer International Publishing, pp. 417–426, 2018. Abstract

Tourism is an industry that has been growing rapidly in the last few years and it is expected that it will continue to grow. Due to the evolution of technology, mobile applications are being increasingly used in all kinds of industries, being one of them tourism. Presently there are already a few mobile applications used to increase the experience of the user when visiting a place, but these mobile applications lack some important features. This paper describes the development of a mobile application with integrated routing algorithms used to increase the experience of the tourists when visiting the city of Avila, Spain. The tourist will have at their disposal real time information about all the monuments available for visit, a full set of predefined circuits with different visit times and degrees of difficulty and also the possibility to create an optimized or personalized circuit combining the user preferences such as visiting time and number of monuments to visit.

Ramos, N. R., P. Pereira, and J. F. Martins, "Smart-meter in power quality", 2017 International Young Engineers Forum (YEF-ECE), pp. 42-46, 5 May, 2017. Abstract

In this paper, an innovative approach for monitoring home electric power quality indicators is presented. Using an electric power analysis device (for this work purpose it will be a smart-meter) and a personal computer it is proved that it is possible to monitor and register electric power quality anomalies, such as long interruptions, voltage dips/swells and frequency oscillations. Through an application developed in Java, a user can view real-time electric parameters, check for electric power quality anomalies and assess load diagram of previous days. Experimental results regarding the application performance are also presented with the respective conclusions.

Inacio, D., J. Murta Pina, P. Pereira, A. Pronto, M. Ventim Neves, and A. Alvarez, "Study of an axial flux disc motor with superconductor rotor", Compatibility and Power Electronics (CPE), 2015 9th International Conference on, Costa de Caparica, Portugal , pp. 488-493, June, 2015. Abstract

The integration of high temperature superconductors (HTS) in electrical machines potentially allows reduction in devices dimensions or performance improvement for the same active volume, when compared with their conventional ones. The use of polycrystalline HTS samples allows big bulk samples. An axial disc motor with HTS material or conventional aluminium in the rotor and conventional armature has been designed and developed. This paper describes simulations and laboratory experiments performed at liquid nitrogen temperature (77 K) in order to analyze the motor's behaviour and its electromechanical characteristics and to define an electric equivalent circuit that allows describing its operation. In order to evaluate the superconducting quality of the bulks and flux pinning phenomena, Hall probe mapping system was performed in order to define the field profiles at 77 K for different polar configurations. The analysis of the obtained results allows confirm the flux pinning phenomena, being the entire rotor magnetized and conclude that the motor with the HTS rotor behaves as a conventional hysteresis motor even though with a different nature, while the motor with aluminium rotor behaves as a conventional induction motor. In asynchronous regime, the HTS motor exhibits a constant torque, higher than the conventional aluminium one. For both cases, the developed torque is proportional to the poles pairs.

Pereira, P., and J. Martins, "Sustainable Heritage Management Towards Mass Tourism Impact: the HERIT-DATA project", 9th International Conference on Intelligent Systems IS’18, Madeira - PT, IEEE, 25-27 Sep., 2018. Abstract

Although tourism is a major engine of economic growth, it also creates a burden hard to manage, and has a great impact on the conservation of the heritage. The HERIT-DATA project aims to reduce the impact of human activities, related to tourism, on cultural heritage, with a special focus on two kind of cultural destinations that can benefit from and be affected by mass tourism: Old towns and places of specific cultural heritage or archaeological interest for visitors, including UNESCO World Heritage Sites. In that framework, HERIT-DATA plans to develop of a sustainable and responsible tourism management towards cultural heritage in MED regions, in particular by taking advantage of technology and innovation in management tools (Smart Cities), as well as other policy and social measures.

Francisco, R., P. Pereira, and J. Martins, "Sustainable Housing Techno-Economic Feasibility Application", Doctoral Conference on Computing, Electrical and Industrial Systems, DoCEIS 2011, vol. 349, Costa de Caparica - Portugal, Springer Boston, pp. 445-454, 2011. Abstract

The high prices currently achieved in the acquisition of non-renewable energy for electricity production and the low levels of energy efficiency in the housing sector are the national situation, which leads the Portuguese government to encourage the acquisition, the installation and the use of technologies which exploit indigenous and renewable energy. This study presents an application that was developed in order to help the citizen in his decision to invest in renewable technologies in their homes. The application is able to elaborate an economic analysis based on the selected type of renewable technology, providing the user with the knowledge of benefits and the annual costs involved in the system that he selected. This tool aims at facilitating the interaction of any user with such technologies and it can be used as a helpful tool to support the decision of investment in such systems.

Delgado-Gomes, V., J. A. Oliveira-Lima, J. F. Martins, C. Lima, and P. Pereira, "Towards to a Web Service alert software system for standard electrical protective devices", Intelligent Engineering Systems (INES), 2012 IEEE 16th International Conference on, Lisbon, Portugal, pp. 197 -201, june, 2012. Abstract

Electrical Protective Devices are key elements in the electrical network. Their purpose is to perform fault detection in electric power systems, by analysing power system voltages and currents. In order to achieve a more centralized control, protective devices can be connected using Web Services through a Service-Oriented Architecture (SOA) approach. This work targets planning and specification of a mapping between Abstract Communication Service Interface (ACSI) Reporting and Device Profile for Web Services (DPWS) Eventing to achieve a better protective electrical devices control, obtaining an event based alert software system, replacing conventional polling-based systems.

Pereira, P., M. H. Fino, and F. V. Coito, "Using discrete-variable optimization for CMOS spiral inductor design", Proc. Int Microelectronics (ICM) Conf, pp. 324–327, 2009. Abstract

In this paper a discrete-variable optimization methodology for the automatic design of CMOS integrated spiral inductors is introduced. The use of discrete variable optimization procedure offers the designer the possibility for exploring the design space exclusively in those points available for the technology under use. Further user-defined constraints between layout parameters may also be incorporated as a way of taking into account design heuristics. A comparison between using discrete-variable optimization and a continuous optimization procedure followed by a discretization of the results is presented, where the benefits of the proposed methodology are presented. An application using the proposed methodology was developed in Matlab and the optimization toolbox is used. For the sake of simplicity the pi-model has been used for characterizing the inductor. The validity of the design results is checked against circuit simulation with ASITIC.

Almeida, P., P. Pereira, and H. Fino, "Using Variable Width RF Integrated Inductors for Quality Factor Optimization", Technological Innovation for the Internet of Things, vol. 394: Springer Berlin Heidelberg, pp. 619-627, 2013. Abstract

The advancement of CMOS technology led to the integration of more complex functions. In the particular of wireless transceivers, integrated LC tanks are becoming popular both for VCOs and integrated filters [1]. For RF applications the main challenge is still the design of integrated inductors with the maximum quality factor. For that purpose, tapered, i.e., variable width inductors have been proposed in the literature. In this paper, analytical expressions for the determination the pi-model parameters, for the characterization of variable width integrated inductors are proposed. The expressions rely exclusively on geometrical and technological parameters, thus granting the rapid adaptation of the model to different technologies. The results obtained with the model are compared against simulation with ASITIC, showing errors below 10%. The model is then integrated into an optimization procedure where inductors with a quality factor improvement in the order of 20-30% are obtained, when compared with fixed width inductors.

Pereira, P., and H. Fino, "VCOSYM -an application for the automatic design of ring VCOS", Proc. 12th IEEE Int. Conf. Electronics, Circuits and Systems ICECS 2005, pp. 1–4, 2005. Abstract

This paper presents an application for the automatic design of ring VCOs. In this application a VCO model based on the Npower transistor model is considered as a away of granting the accuracy of results for submicron technologies. In order to easily integrate any VCO previously designed into a PLL automatic design tool, a corresponding linear model of the VCO is automatically generated, yielding a simple and precise characterization for higher level system design. The design of a 150 MHz VCO using a seven stage ring topology is presented. The validity of the design obtained is checked against Hspice simulation of the circuit.

Afonso, M., P. Pereira, and J. Martins, "Weather Monitoring System for Renewable Energy Power Production Correlation", Doctoral Conference on Computing, Electrical and Industrial Systems, DoCEIS 2011, vol. 349, Costa de Caparica - Portugal, Springer Boston, pp. 481-490, 2011. Abstract

This work describes the development of a system designed for renewable power generation integration. It continuously acquires wind, solar and temperature data, which is automatically correlated with energy parameters, obtained from renewable energy systems. The developed system was installed in an urban building equipped with photovoltaic cells and wind renewable generation. To validate the developed application, it was analyzed data of a wind generator and a set of photovoltaic panels, installed near to the weather station. The developed application allows, in addition to the acquisition of weather and energy data, their continuous monitoring and correlation through a graphical user interface, providing a friendly interactivity with the user.

Book Chapter
Pereira, P., H. Fino, M. Fakhfakh, F. Coito, and M. Ventim-Neves, "LC-VCO Design Challenges in the Nano-Era", Analog/RF and Mixed-Signal Circuit Systematic Design, vol. 233: Springer Berlin Heidelberg, pp. 363-379, 2013. Abstract

The progressive scaling of CMOS technology towards nanometre sizes has made the implementation of highly integrated systems for the wireless communication systems possible. Additionally, higher speed, lower power consumption and area reduction has been reached. Due to the high-density integration needs, as well as to low cost fabrication, RF applications, such as the LC-voltage controlled oscillator (LC-VCO), are usually implemented in CMOS technology. The complexity of designing LC-VCOs has lead to the development of several design methodologies. This chapter introduces an optimization based methodology for the design of LC-VCOs, where its efficiency is granted by the use of analytical models to characterize the active and passive elements’ behaviour.

Pereira, P., F. Passos, and H. M. Fino, "Optimization-Based Design of RF-VCOs with Tapered Inductors", Performance Optimization Techniques in Analog, Mixed-Signal, and Radio-Frequency Circuit Design, Hershey, PA, USA, IGI Global, pp. 134 - 157, 2015. Abstract

Voltage-Controlled Oscillators (VCOs) are widely used in wireless transceivers. Due to the stringent specifications regarding phase-noise, LC-VCOs are usually adopted. The need for maximizing phase-noise as well as minimizing the power consumption makes imperious the adoption of optimization-based design methodologies. For the optimization of the LC-VCO characteristics, special attention must be paid to the integrated inductor design, since its quality factor may have a strong influence in the LC-VCO phase-noise. Furthermore, designers must ensure that the higher limit of VCO operating frequency is sufficiently below the inductor resonant frequency. In this chapter, a study on the influence of the quality factor of the inductors on the LC-VCO overall behavior is presented. Then, optimization of integrated inductors by exploring the inductor geometric layout is presented. Finally, results obtained for the design of an LC-VCO in 130nm Technology using a previously optimized inductor are presented.

Sallem, A., and P. Pereira, "Sensitivity Analysis in the Optimization of Analog Active Filters by Applying the Richardson Extrapolation", Focus on Swarm Intelligence Research and Applications: Nova Science Publishers, pp. 247-275, 2017. Abstract

The key step of the analog active filter design is the optimal selection of component values due to manufactured series (E12, E24, E48, E96 and E192). In this paper, four simulation-based metaheuristics are applied to optimize four active filters using commercials available ICs as building blocks. The emphasis of this work is applying Richardson extrapolation-based sensitivity analysis in the optimization process of analog active filters. Indeed, Richardson extrapolation technique facilitates the calculation of the partial derivatives for the sensitivity using the simulation-based evaluation, without an explicit mathematical expression. Viability and benefits of the sensitivity analysis are highlighted. Monte Carlo analysis is performed in order to investigate robustness of the proposed sensitivity analysis of the active filters in case of component value variations due to specified tolerances of manufactured series.

Pereira, P., A. Sallem, M. Fakhfakh, M. H. Fino, and F. Coito, "A Technology-Aware Optimization of RF Integrated Inductors", Analog Circuits: Applications, Design and Performance: Nova Science Publishers, Inc., pp. 213-234, February, 2012. Abstract

This Chapter presents the optimal design of radio-frequency integrated spiral inductors. The basic idea is to generate an analytical model to characterize integrated inductors based on the double {\ensuremathπ}-model, and offer to the designer an approach to determine the inductor layout parameters. Particle Swarm Optimization technique is used to generate optimal values of parameters of the developed models. Viability of the proposed models is highlighted via comparison with ASITIC simulation results.

Coito, F., H. Fino, and P. Pereira, "Variability-Aware Optimization of RF Integrated Inductors in Nanometer-Scale Technologies", Integrated Circuits for Analog Signal Processing, New York, Springer-Verlag, pp. 271-287, 2013. Abstract

Progressive scaling of CMOS technology towards nanoscale regime enables the design of highly integrated systems for the wireless communications market. As technology continues to scale, the variability in process parameters may cause significant deviations in device behaviour. The complexity of designing spiral inductors has lead to the development of multi-objective optimization based design methodologies yielding the generation of Pareto-optimal surfaces. However, the variability of the process parameters is usually ignored, yielding the selection of ideally optimal solutions in detriment of quasi-optimal solutions that may prove to be better, should the robustness against process parameter variation be accounted for. We propose the generation of an extended Pareto front containing both optima and quasi-optima solutions. Finally information on the robustness to process parameter variations, is used for electing the best design solutions.The evaluation of the extended set of sub-optima solutions requires methods capable to find the set of local optima, since solutions that are close to each other in the performance index space may be very distant in the design parameter space.

, Focus on Swarm Intelligence Research and Applications, : Nova Science Publishers, 2017. AbstractWebsite

Swarm intelligence techniques are among the most talented and successful approaches that gained a lot of popularity over the past two decades. They are inspired by animal behavior (such as ants, termites and bees) and insect conduct (by swarm, herd, flock and shoal phenomena) in order to develop these techniques in terms of mimicking their problem/solution abilities. These techniques provide good approximate solutions in a reasonable time for solving hard and complex problems in many engineering fields. This book is intended for researchers, engineers and graduate students with interests in swarm intelligence algorithms and their applications. It discusses and describes the various swarm intelligence techniques as useful tools for solving practical problems, such as urban traffic optimization, electrical engineering problems and the design of integrated analog circuits.