Arturo Fajardo

• Doctor of Engineering
• Professor (Asociate) at Pontifical Xavierian University

Several wireless communication technologies, including Wireless Sensor Networks (WSNs), are essential for Internet of Things (IoT) applications. WSNs employ a layered framework to govern data exchanges between sender and recipient, which facilitates the establishment of rules and standards. However, in this conventional framework, network data shar...

Isolated water and energy microgrids (IWEMGs) serve as vital solutions for enhancing the well-being of remote and rural communities, particularly in areas where water and energy resources are scarce. This has spurred research into the interdependence between the water and energy sectors (water–energy nexus), a field that has grown in response to te...

Aloe Barbadensis Miller, commonly known as Aloe vera, has been widely used in different applications, such as medicinal treatments and cosmetic products. However, its transportation and handling present challenges due to oxidation and property loss caused by direct environmental exposure. A strategy to mitigate these effects is dehydration, where d...

In contemporary mobile communications markets, various agents or players interact to pursue welfare. Regulatory policies enacted by governments in certain markets aim to maximize social welfare. However, some countries, both least developed and developing, often adopt successful models from developed nations without local market validation. Therefo...

24-pulse diode rectifiers have been extensively studied and adopted in industrial applications due to their low output ripple, high average voltage, and low input current harmonic distortion. Increasing the number of rectified pulses has been proven to be effective for canceling lower-order harmonics. To do so, some proposed topologies use multi-ta...

Wireless communication supports various real-world applications, such as aeronautical navigation, satellite and TV broadcasting, wireless LANs, and mobile communications. The inherent characteristics of the electromagnetic spectrum impose constraints on telecommunication channels and their frequency bandwidths within mobile networks. A persistent c...

This paper studies and analyzes the approximation of one-dimensional smooth closed-form functions with compact support using a mixed Fourier series (i.e., a combination of partial Fourier series and other forms of partial series). To explore the potential of this approach, we discuss and revise its application in signal processing, especially becau...

Actualmente, se pretende dotar de autonomía energética y movilidad a los dispositivos electrónicos. Por ejemplo, las baterías en implantes miniaturizados pueden evitarse usando sistemas de transferencia de energía inalámbrica basados en enlaces inductivos asimétricos eficientes. En estos enlaces, el inductor del transmisor funciona cerca de su frec...

Wireless sensor networks (WSNs) have been adopted in many fields of application, such as industrial, civil, smart cities, health, and the surveillance domain, to name a few. Fateway and sensor nodes conform to WSN, and each node integrates processor, communication, sensor, and power supply modules, sending and receiving information of a covered are...

Bicycles are rapidly gaining popularity as a sustainable mode of transportation around the world. Furthermore, the smart bicycle paradigm enables increased use through the Internet of Things applications (e.g., GPS tracking systems). This new paradigm introduces energy autonomy as a new challenge. The energy harvesting technology can capture the en...

This paper describes the validation of an experimental E-field and Specific Absortion Rate (SAR) measurement setup for RF exposure assessment in a human flat phantom model. The requirements of standards related to RF dosimetry were taken into account for the integration of the experimental setup. From the various test cases tackled, we present resu...

Dielectric-based measurement techniques have been shown to be very effective in determining the properties of various materials. These techniques have been widely used in a variety of fields and applications. Time Domain Transmission (TDT) techniques have grown in popularity because they are practical, non-destructive, provide measurements in real...

Magnets are now used in a variety of applications, including data storage, audio generation, sensing devices, and electric energy generators. Neodymium magnets (NdFeB) are the most commonly used permanent magnets due to their hardness and magnetic field strength. Simulations are useful in the design of magnet-based devices because they reduce costs...

Low Power Wide Area Networks (LPWAN) have emerged as an attractive Internet of Things (IoT) communication option. When deploying a communication network to support IoT applications, large coverage and low power consumption are critical requirements. Despite the fact that existing LPWAN technology solutions promote IoT requirements such as long comm...

To ensure high-quality educational processes, more educational research should be developed about student experiences during the COVID-19 pandemic. Furthermore, the student's perception about distance learning education (under the current situation) could be used as input for instructors and educational institutions to guide their distance learning...

This paper presents a methodology for determining the optimal portfolio allocation for a demand response aggregator. The formulation is based on Day-Ahead electricity prices, in which the aggregator coordinates a set of residential consumers that are recruited through contracts. Four types of contracts are analyzed, considering both direct and indi...

In this paper, a novel SIBO (Single-Inductor Bipolar-Output) DC/DC Boost converter is proposed to power OLED (Organic Light-Emitting Diode) microdisplays. The proposed topology merges a conventional SISO (Single-Inductor Single-Output) DC/DC Boost converter and a switched capacitor inverter to produce a SIBO converter without both the cross-regulat...

This paper explores the design of a Class-E amplifier with finite DC-feed inductance using three tuning methods. Furthermore, this work quantifies the impacts of the tuning process (referred to in this paper as the tuning effect) on the main figures of merit (FoMs) of this amplifier. The tuning goals were to guarantee two conditions: zero voltage a...

This paper describes the design of a minimum cost web interface for object tracking applications based on open (or free) tools. Furthermore, the different blocks and parts that compose it were detailed; this paper was written as a tutorial to motivate engineers and students with basic knowledge on programming tools to integrate these web interfaces...

This paper describes the design and implementation of an object tracking system based on LoRa, Firebase, andMapbox. The proposed system allows real-time visualization of the tracking nodes in a web interface following a low-cost and low-complexity design approach. The cost of each tracking node and the gateway were USD 39.38 and USD 28.00, respecti...

This paper proposes new closed expressions of self-impedance using the Method of Moments with the Point Matching Procedure and piecewise constant and linear basis functions in different configurations, which allow saving computing time for the solution of wire antennas with complex geometries. The new expressions have complexity O(1) with well-defi...

This paper proposes an analytical expression set to determine the maximum values of currents and voltages in the Class-E Power Amplifier (PA) with Finite DC-Feed Inductance (FDI) under the following assumptions—ideal components (e.g., inductors and capacitors with infinite quality factor), a switch with zero rise and fall commutation times, zero on...

Atmospheric Water Generators (AWG) are a promising technology solution to the water scarcity in the world. However, their main drawback is the high power consumption. This paper presents the experimental optimization process of a Portable Atmospheric Water Generator (PAWG) prototype based on a thermometric cooler. This process was developed by an e...

The Class-E with finite feed inductance is a high-efficiency power amplifier that generally uses complex, long, and iterative design procedures. In this paper, we detail a design methodology that is based on an analytical model of this amplifier. This methodology explores the power amplifier design by the use of a symbolic mathematical tool, which...

The primary coil of an efficient asymmetric inductive link (IL) has a high quality factor and operates near its self-resonance frequency (SRF). Therefore, its characterization is challenging, especially because the measurement instruments must be able to measure a large reactance and a very small resistance at a frequency where the inductor radiate...

In this paper, using an extended version of the 1-diode/2-resistors (1D&2R) circuit model, we propose a methodology suitable for modeling Photovoltaic Solar Cells (PVSCs) operating in indoor environments. With low-cost equipment and low-complexity procedures, this methodology finds an equivalent circuit that reproduces the worst-case performance of...

Context: In advanced ultralow-power devices, it is necessary to use the accuracy extraction procedures of the MOSFET threshold voltage to fully characterize the devices. These procedures are based in the measurement of the Tran-conductance efficiency (gm/ID) and its first derivative in function of the voltage gate source (d(gm/ID)/dVGS). In order t...

Design equations for the standard Quasi Yagi-Uda antenna built on 60 mil FR4 are presented to be used on fixed wireless telecommunication systems, Wi-Fi, WiMAX and LTE. In this work, the design equations are systematically proposed for the band between 1 GHz and 3 GHz, where relative bandwidth is better than 39%, the cross-polarization is lower tha...

This paper presents a step-by-step design procedure for a Class-E Power Amplifier, focusing in the consequences that component variations (re-tuning) have on the overall circuit performance, based on certain evaluation parameters. A proper analysis of these parameters shows that a traditional re-tuning procedure, whose main goal is to achieve zero...

This paper presents the FLEXOR platform, a modular tool for prototype Wearable Body Area Network (WBAN) applications. This platform is intended to reduce costs, effort and complexity of a WBAN project. The platform is set to a star topology, and allows the configuration of active modules, independent sampling times and ID assignation to each node t...

En este artículo se presenta el diseño, la implementación y la evaluación de un híbrido Rat-race miniaturizado, construido en un substrato CER-60 con líneas de transmisión (LxTx) tipo micro­cinta, siguiendo una curva de llenado fractal no­vedosa. Este circuito es el resultado principal del proyecto de investigación PS 3206 financiado por la Vicerre...

This paper presents the design, implementation and evaluation of a miniaturized Rat-race hybrid implemented in substrate CER-60 with microstrip transmission lines in a novel space-filling curve. This circuit is the main research's result of the project PS 3206funded by the Pontificia Universidad Javeriana. The hybrid achieves a miniaturization of 7...

This paper gives a detailed description of a nonconventional speed-variation linear model intended for a conventional three-phase induction motor. The proposed architecture consists in a single-phase unit-power-factor tap (PFC) followed by three-phase inverter, which feeds the motor by using the scalar-control technique. The whole system is digital...

This paper gives a detailed description of a non-conventional speed-variation linear model intended for a conventional three-phase induction motor. The proposed architecture consists in a single-phase unit-power-factor tap (PFC) followed by three-phase inverter, which feeds the motor by using the scalar-control technique. The whole system is digita...

The design of a new broadband quasi Yagi-Uda antenna is presented. The antenna is composed of an electromagnetic band-gap (EBG)-truncated ground plane and a feeding network formed by a Marchand balun and a coupling network. The quasi Yagi-antenna was designed to work at a central frequency of 3.5 GHz using a 30-mil FR4 substrate. The simulated and...

This article presents a design methodology for low noise amplifiers (LNA) in the UHF band, optimized for narrowband operation, based on a proper choice of the bias operating point, modeling of the active element through S parameters and the appropriate design of matching networks for minimum noise figure and maximum gain under stable conditions. Li...

This paper presents a conventional analysis for narrowband operation using odd-even technique for the ideal structures of the Branch-line and Rat-Race Hybrids. Additionally, it presents the simulated results obtained whit Ansoft Designer^® platform, using ideal transmission lines in order to characterize the hybrids through their merit pa...

This paper presents an image synthesis algorithm for rendering views of a real scene taken with a virtual camera which is located between two real cameras. Specifically, this paper presents how, under certain conditions, a pair of views is enough to obtain a full set of possible views by following the line that joins their optical centers (baseline...

This paper presents a practical application of a modern methodology for analyzing the effects of structured uncertainty in the internal stability of the current control loop of a rectifier with unitary power factor in half bridge configuration. The proposed approach is based on the complementary combination of two main mathematical concepts: the Li...

This paper presents a modelling of a rectifier with unity power factor (PFC) in half bridge configuration. The proposed approach is based on the movable average technique and quasi-static process analysis. This methodology is applied to find the transfer functions that describe the dynamics of the PFC, under a cascade control structure of internal...

En este artículo se presenta un modelo lineal de un rectificador monofásico con factor de potencia unitario (CPF) en configuración medio puente. El modelo propuesto se obtiene a través de la técnica de promedio móvil y análisis cuasi estático. Esta metodología se aplica al CPF a fin de encontrar las funciones de transferencia que rigen su comportam...

This paper presents an image synthesis algorithm for rendering views of a real scene taken with a virtual camera which is located between two real cameras. Specifically, this paper presents how, under certain conditions, a pair of views is enough to obtain a full set of possible views by following the line that joins their optical centers (baseline...

This paper presents an image synthesis algorithm for rendering views of a real scene taken with a virtual camera which is located between two real cameras. Specifically, this paper presents how, under certain conditions, a pair of views is enough to obtain a full set of possible views by following the line that joins their optical centers (baseline...