Elson Agastra

Multiobjective Optimization Techniques

Designing an electronic system is an engineering task bound to the satisfaction of a given set of requirements. If it is possible to express the compliance of the system to the requirements in a mathematical form giving a measure of how much a given system is far from compliance, then it would be possible to obtain the desired performances by seeking for the minimum of such a function. Seeking the minimum of a function is a daunting task to which a whole branch of mathematics, optimization, is devoted. In the case in which the design must comply to several requirements, it is usually more practical and interesting to define a set of functions to be minimized altogether. In this case the search for an optimal point, or a set of points, can be performed by applying a multi-objective optimization technique. This chapter will investigate popular multi-objective optimization techniques, giving both their basics and describing recent advancements. For the selected techniques, performances over a set of benchmarks will be presented, as well as results over relevant electronic engineering problems. Keywords: multi-objective optimization; evolutionary algorithms; genetic algorithms

Poster: Downlink free space loss compensation through receiver bandwidth selectivity at LEO satellite ground stations

Low Earth Orbit (LEO) satellites are used for public networking and for scientific purposes. Communication via satellite begins when the satellite is positioned in its orbital position. Ground stations can communicate with LEO satellites only when the satellite is in their visibility region, since LEO satellites move too fast relative to a fixed point (ground station) on the Earth. The major loss in communication between the LEO satellite and the ground station is the free space loss. Free space loss varies since the distance from the ground station to the satellite varies over time. Free space loss is usually compensated through variable satellite transmit power on the downlink. This paper tries another approach on free space loss compensation, through receiver bandwidth adjustability at the ground station, in order to obtain the constant margin at the receiver. For analytical and simulation purposes, the altitudes from 600km to 1200km are considered.

Low cost QoS and RF power measuring tool for 2G/3G mobile network using Android OS platform

The proliferation of corporate and end user mobile internet services offered for smartphones and tablets, makes it necessary to monitor the quality of service and experience provided by mobile internet service providers. In this context, we introduce a low cost tool for monitoring network parameters as received signal power and network responding time. The application is used for signal and latency monitoring for fast and slow moving users in a surveyed area especially for in car communication. The developed application can be useful for mobile operators in order to improve their network quality as well as for end users who can get an insight into the quality of service offered by their service provider. In the proposed application, two software tools are used; first, the capabilities of the android programming interface and second the PHP scripting for measured data post-processing and reporting on web servers. The application is currently tested in Tirana, Albania for evaluating the network parameters of mobile providers showing that only monitoring the received signal power level is not sufficient for assuming a good quality of service.

Attachment Modes in the Method of Moments in Time-Domain

E-cient and accurate modeling of electromagnetic structures is valuable in antenna analysis and design, and time domain solutions are at a premium over frequency domain in the case of ultra wide band signals or transients. Among the full wave electromagnetic methods in time domain the method of moments in time domain (MoM-TD) is very interesting. Such a method can be implemented, as for frequency domain, either resorting to a thin wire approximation or to a surface patch model. Depending on the structure to be analyzed one or the other is most convenient. For heterogeneous structures both implementations might be needed, and the problem of the attachment between a perfectly conducting thin wire and a perfectly conducting surface is hence relevant. In this paper, attachment modes are introduced in MoM-TD. The solution is validated on a test case and against another numerical technique.

High Gain Compact Strip and Slot UWB Sinuous Antennas

Three ground-backed compact strip-and slot-sinuous antennas are analyzed. Proposed configuration allows for a single lobe, polarization-versatile, high efficiency, and ultrawide band antenna not needing a cumbersome lossy back cavity typical of conventional single-lobe sinuous antennas. Simulations show attained performances as well as tuning possibilities.

J.C. Maxwell's Forerunners: Riccardo Felici [Historical Corner]

Riccardo Felici (Figure 1) was born on June 11, 1819, in Parma. Parma was then the capital city of the eponymous duchy governed by Maria Luigia, wife of Napoleon and daughter of the Emperor of Austria, Francis II. Felici studied at the University of Pisa, where he received his degree on July 12, 1843. In 1846, he was nominated assistant to Carlo Matteucci [Forlì, Italy, June 21, 1811 - Leghorn, Italy, July 25, 1868] (Figure 2). Matteucci was the founder of Il Cimento (The Endeavor), a journal of physics, chemistry, and natural history (1844), and later founder of Il Nuovo Cimento (The New Endeavor) (1855), which is still a major physics journal in Italy. Matteucci was a pioneer in electrochemistry and electrophysiology, discovering the presence of electrical phenomena in muscle contraction, and independently from Faraday formulating the laws of electrolysis.

Modeling of Radio Base Stations with the Numerical FDTD Method, for the Electromagnetic Field Evaluation

Settling down an efficient and reliable procedure for the evaluation of the EMF exposure, from the Base Station Antennas, is important for mobile communications. In this work a calculation method of the exposure under radiofrequency, due to the presence of some antennas of the cellular Base Stations is introduced. The model of wave diffusion in free space, under ideal conditions gives ground for a convenient calculation of the exposure, even in cases of a considerable distance from the antenna, whose covering area is considerably larger, thus resulting in overestimation of the exposure. The calculation of the electrical intensity of the radiation is possible when the technical specifications of the given antenna (provided by the manufacturer) are known and by defining the position of the given point in relation to the antenna.

Data Interpretation Using Mobile Uncalibrated Sensor for Urban Environmental Monitoring

Intelligent Transportations Systems (ITS) are complex information and communication technologies platforms aimed for a better and cost effectiveness public transport organization. Our aim is to extend the basic of ITS platform for real time environmental data monitoring and processing. Mobile environmental sensing is becoming one of the best options to monitor our environment due to its high flexibility. In this context, the proposed system utilizes public transportation vehicle intelligence and sensing to monitor a set of environmental parameters over a large area by “filling in the gaps” where people go but environmental monitoring sensor infrastructure has not yet been installed. In this article, we show as well how to extract useful data from low cost and uncalibrated environmental sensor nodes. The presented architecture is focused on low cost and highly scalable architecture in term of type and number of sensors that can be installed and processed. This work presents some data from a testing deployed infrastructure in Albania and the measured data indicate the usefulness of the proposed architecture.

The Apsidal Precession for Low Earth Sun Synchronized Orbits

By nodal regression and apsidal precession, the Earth flattering at satellite low Earth orbits (LEO) is manifested. Nodal regression refers to the shift of the orbit’s line of nodes over time as Earth revolves around the Sun. Nodal regression is orbit feature utilized for circular orbits to be Sun synchronized. A sun¬-synchronized orbit lies in a plane that maintains a fixed angle with respect to the Earth-Sun direction. In the low Earth Sun synchronized circular orbits are suited the satellites that accomplish their photo imagery missions. Nodal regression depends on orbital altitude and orbital inclination angle. For the respective orbital altitudes the inclination window for the Sun synchronization to be attained is determined. The apsidal precession represents major axis shift, respectively the argument of perigee deviation. The apsidal precession simulation, for inclination window of sun synchronized orbital altitudes, is provided through this paper.

The Pavers of Maxwell's Pathway to His Equations [Historical Corner]

In this contribution, we will analyze and briefly present the scientists cited by Maxwell in his 1864 dissertation, “A Dynamical Theory of the Electromagnetic Field” [1]. The analysis will distinguish between researchers that are merely mentioned by Maxwell and those for which a precise citation to published papers is given. For the sake of clarity, since in [1] citations were often given in a very short form without titles or pages, the full bibliographical references are given here [2-26]. Furthermore, for these papers we will also inves tigate the “second-level citations,” that is, researchers cited by those cited by Maxwell. A third-level investigation was done only for [27], which is a self-citation by Maxwell in [2].