Electrical Engineering Community Research Articles

Overview of Consensus Protocol and Its Application to Microgrid Control

Different control strategies for microgrid applications have been developed in the last decade. In order to enhance flexibility, scalability and reliability, special attention has been given to control organisations based on distributed communication infrastructures. Among these strategies, the implementation of consensus protocol stands out to cooperatively steer multi-agent systems (i.e., distributed generators), which is justified by its benefits, such as plug and play capability and enhanced resilience against communication failures. However, as the consensus protocol has a long trajectory of development in different areas of knowledge including multidisciplinary subjects, it may be a challenge to collect all the relevant information for its application in an emerging field. Therefore, the main goal of this paper is to provide the fundamentals of multi-agent systems and consensus protocol to the electrical engineering community, and an overview of its application to control systems for microgrids. The fundamentals of consensus protocol herein cover the concepts, formulations, steady-state and stability analysis for leaderless and leader-following consensus problems, in both continuous- and discrete-time. The overview of the applications summarises the main contributions achieved with this technique in the literature concerning microgrids, as well as the associated challenges and trends.

What is the gradient of a scalar function of a symmetric matrix?

Perusal of research articles that deal with the topic of matrix calculus reveal two different approaches to calculation of the gradient of a real-valued function of a symmetric matrix leading to two different results. In the mechanics and physics communities, the gradient is calculated using the definition of a \frechet derivative, irrespective of whether the argument is symmetric or not. However, members of the statistics, economics, and electrical engineering communities use another notion of the gradient that explicitly takes into account the symmetry of the matrix, and this "symmetric gradient" $G_s$ is reported to be related to the gradient $G$ computed from the \frechet derivative with respect to a general matrix as $G_s = G + G^T - G \circ I$, where $\circ$ denotes the elementwise Hadamard product of the two matrices. We demonstrate that this relation is incorrect, and reconcile both these viewpoints by proving that $G_s = \mathrm{sym}(G)$.

Modeling and simulating in-memory memristive deep learning systems: An overview of current efforts

Deep Learning (DL) systems have demonstrated unparalleled performance in many challenging engineering applications. As the complexity of these systems inevitably increase, they require increased processing capabilities and consume larger amounts of power, which are not readily available in resource-constrained processors, such as Internet of Things (IoT) edge devices. Memristive In-Memory Computing (IMC) systems for DL, entitled Memristive Deep Learning Systems (MDLSs), that perform the computation and storage of repetitive operations in the same physical location using emerging memory devices, can be used to augment the performance of traditional DL architectures; massively reducing their power consumption and latency. However, memristive devices, such as Resistive Random-Access Memory (RRAM) and Phase-Change Memory (PCM), are difficult and cost-prohibitive to fabricate in small quantities, and are prone to various device non-idealities that must be accounted for. Consequently, the popularity of simulation frameworks, used to simulate MDLS prior to circuit-level realization, is burgeoning. In this paper, we provide a survey of existing simulation frameworks and related tools used to model large-scale MDLS. Moreover, we perform direct performance comparisons of modernized open-source simulation frameworks, and provide insights into future modeling and simulation strategies and approaches. We hope that this treatise is beneficial to the large computers and electrical engineering community, and can help readers better understand available tools and techniques for MDLS development.

Do Energy Oscillations Degrade Energy Transfer in Electrical Systems?

There is the view, widespread in the electrical engineering community, that the effectiveness of energy transfer in electrical systems, thus the power factor, is reduced by energy oscillations which, according to this view, are the cause of the reactive power. This view is challenged in this article. It demonstrates on a variety of circuits that this view is not right. Power factor can decline without energy oscillations, or energy oscillations do not cause its decline. In addition, the reactive power can occur in the absence of energy oscillations or their presence does not cause the reactive power. This observation has not only cognitive but practical merit as well. According to Instantaneous Reactive Power p-q theory, to improve the power factor, energy oscillations between the supply source and the load should be compensated. Because this conclusion is erroneous, an active power filter, controlled according to this recommendation in the presence of the supply voltage distortion or/and asymmetry, instead of improving the power factor can worsen it. The physical meaning of the reactive power is also investigated in this article, with the conclusion that there is no physical phenomenon in electrical systems that could be described in terms of reactive power.

К 140-летию Международной электрической выставки 1881 года в Париже. Ч. 1. Электрическая лихорадка

This exhibition, which was dedicated solely to electricity, pursued primarily scientific, technical and educational goals. The commercial component was in the second place. Under the banner of the new science, thousands of scientists, engineers, inventors, entrepreneurs, and enthusiasts from different countries and continents succeeded to unite for the first time and clearly show the whole world the prospects for development in the near future. The First International Congress of Electricians, held within the framework of the exhibition, overcame scientific and state differences and developed a unified approach to electrical units. The International Electrical Exhibition was a kind of the electrical engineering community crystallization point, a platform for its consolidation, the unity of which the time was unable to destroy. The first part of the article shows the great efforts done by the organizing committee on preparing the electrical exhibition. Special attention is paid to the exhibition expositions, its main halls and pavilions. Testimonials of eyewitnesses of those events are given.

К 140-летию Международной электрической выставки 1881 года в Париже. Ч. 2. Самый понятный урок

This exhibition, which was dedicated solely to electricity, pursued primarily scientific, technical and educational goals. The commercial component was in the second place. Under the banner of the new science, thousands of scientists, engineers, inventors, entrepreneurs, and enthusiasts from different countries and continents succeeded to unite for the first time and clearly show the whole world the prospects for development in the near future. The First International Congress of Electricians, held within the framework of the exhibition, overcame scientific and state differences and developed a unified approach to electrical units. The International Electrical Exhibition was a kind of the electrical engineering community crystallization point, a platform for its consolidation, the unity of which the time was unable to destroy. The first part of the article [1] shows the great efforts done by the organizing committee on preparing the electrical exhibition. Special attention is paid to the exhibition expositions, its main halls and pavilions. Testimonials of eyewitnesses of those events are given. The second part is devoted to the 1st International Congress of Electricians, its main objectives and results. It tells about Thomas Edison's lighting system, which became the central event of the exhibition. The final event of the exhibition on awarding participants is described.

Introduction to spin wave computing

This paper provides a tutorial overview over recent vigorous efforts to develop computing systems based on spin waves instead of charges and voltages. Spin-wave computing can be considered a subfield of spintronics, which uses magnetic excitations for computation and memory applications. The Tutorial combines backgrounds in spin-wave and device physics as well as circuit engineering to create synergies between the physics and electrical engineering communities to advance the field toward practical spin-wave circuits. After an introduction to magnetic interactions and spin-wave physics, the basic aspects of spin-wave computing and individual spin-wave devices are reviewed. The focus is on spin-wave majority gates as they are the most prominently pursued device concept. Subsequently, we discuss the current status and the challenges to combine spin-wave gates and obtain circuits and ultimately computing systems, considering essential aspects such as gate interconnection, logic level restoration, input–output consistency, and fan-out achievement. We argue that spin-wave circuits need to be embedded in conventional complementary metal–oxide–semiconductor (CMOS) circuits to obtain complete functional hybrid computing systems. The state of the art of benchmarking such hybrid spin-wave–CMOS systems is reviewed, and the current challenges to realize such systems are discussed. The benchmark indicates that hybrid spin-wave–CMOS systems promise ultralow-power operation and may ultimately outperform conventional CMOS circuits in terms of the power-delay-area product. Current challenges to achieve this goal include low-power signal restoration in spin-wave circuits as well as efficient spin-wave transducers.

High order discontinuous Galerkin methods for time-domain and frequency-domain nanophotonics

The discontinuous Galerkin (DG) method is a general numerical modeling approach that has been extensively studied in the last 20 years for the solution of many systems of partial differential equations in physics. Its development for the numerical treatment of the system of Maxwell equations was initiated by the applied mathematics community in the early 2000s. It is now a very popular method for time-domain electromagnetics, which is increasingly used and further developed by the applied physics and electrical engineering communities. More recently, a specific variant of DG, referred to as hybridized DG (or HDG), has been proposed for frequency-domain electromagnetics. DG methods possess nice features that make them particularly attractive for dealing with heterogeneous media and irregularly shaped or curved geometries, and more generally with multiscale problems. Not surprisingly, the method has also been adopted by researchers in the nano-optics field. In this paper, we report on our recent efforts for extending the capabilities of this family of methods for the numerical modeling of nanoscale light-matter interactions.

Power Quality Detection, Classification and Monitoring Using LABVIEW

In recent years, Power Quality becomes increasingly a major concern for both electric utilities and end users. Accordingly, the electrical engineering community has to deal with the analysis, diagnosis and solution of PQ issues using system approach rather than handling these issues as individual problems. This paper describes the analysis of PQ using advanced signal processing tools represented in Hilbert & Wavelet Transforms (HT-WT) and artificial intelligence tools represented in Artificial Neural Network & Support Vector Machine (ANN-SVM) for detection and classification of power quality disturbances respectively. These techniques were successfully simulated using LABVIEW software capabilities. The results of simulation indicate that the signal processing techniques are effective mechanisms to detect and classify power quality disturbances. At the end, the combination of WT as a tool of detection and features extraction with SVM as a classifier tool resulted as the best combination for PQ monitoring system.

Efficiency Assessment of Induction Motors Operating Under Different Faulty Conditions

Fault diagnosis in induction motors has been a topic that has drawn an increasing attention among the electrical engineering community, including both industry and academia. Diverse techniques have been developed in order to detect the presence of possible faults in their early stages so that forced outages of the motor and consequent economic consequences can be avoided. However, little attention has been paid to the implications of the presence of these faults in terms of motor efficiency reduction. The efficiency drops caused by the existence of faults or anomalies in the motor, which can be present during long time intervals, can lead to economic losses that can be even greater than those caused by eventual motor outages. In spite of this fact, many industrial users are not aware of the efficiency repercussions of the operation under unhealthy conditions. As a consequence, it becomes necessary to accurately study and quantify the efficiency decrements caused by the presence of possible failures, so that the users can have this information available to adopt proper maintenance decisions. This paper analyses how different noncatastrophic failures influence the value of motor efficiency; different types of rotor faults as well as bearing failures are considered. In this paper, it is shown that the presence of these failures indeed strongly affects the motor efficiency and may have serious implications on the motor performance and operational cost.

A Review and Mathematical Treatment of Infinity on the Smith Chart, 3D Smith Chart and Hyperbolic Smith Chart

This work describes the geometry behind the Smith chart, recent 3D Smith chart tool and previously reported conceptual Hyperbolic Smith chart. We present the geometrical properties of the transformations used in creating them by means of inversive geometry and basic non-Euclidean geometry. The beauty and simplicity of this perspective are complementary to the classical way in which the Smith chart is taught in the electrical engineering community by providing a visual insight that can lead to new developments. Further we extend our previous work where we have just drawn the conceptual hyperbolic Smith chart by providing the equations for its generation and introducing additional properties.

Modeling of charge transport in insulating dielectric for gas-insulated transmission line based on multiple trap levels

Space charge behavior in polymeric materials is of interest to the electrical engineering community and has significant effects on the behavior of the polymers that are used in gas-insulated transmission lines (GILs). For example, the space charge in certain insulating materials can cause severe distortion of the electric field that may even lead to breakdown of the materials. It is therefore important to understand the trapped charge distributions in these materials because they can be used as novel indicators for effective evaluation of the aging status and the electric withstand strength of these insulating materials. This paper addresses recent developments in the modeling of charge transport in polymers for use in GIL applications. A numerical model of bipolar charge transport in polymeric insulators is presented in this paper. This model was studied based on use of multiple trap levels and consideration of symmetrical parameters for the generation and transport of electrons and holes.

Tutorial on X-Ray Free-Electron Lasers

This paper provides a tutorial on X-ray free-electron lasers (XFELs) which are currently being designed, built, commissioned, and operated as fourth-generation light sources to enable discovery science in materials science, biology, and chemistry. XFELs are complex devices, driven by high-energy, high-brightness electron accelerators and cost on the order of $B. Here, we provide a basic introduction to their operating physics and a description of their main accelerator components. To make their basic operating principle accessible to the electrical engineering community, we rederive the FEL dispersion relation in a manner similar to that done for traveling-wave tubes. We finish with sections describing some unique features of the X-rays generated and on the physics that lead to the main design limitations, including approaches for mitigation.

Survey about Classical and Innovative Definitions of the Power Quantities Under Nonsinusoidal Conditions

AbstractToday, electric power and energy measurements are widely required, practically in all the research, industrial and consumer applications. Power measurements are of importance primarily for the test, monitoring and maintenance of energy supply networks and electric equipment. The measurement of both electric power and energy is a still open research problem in the electrical engineering community. Phenomena like harmonic distortion, noise, transients, over-voltages and voltage dips have increased the difficulty in achieving accurate measurements, compared with the case of sinusoidal signals. Many of the non-active power component definitions that have been proposed cannot be implemented in the traditional electro-mechanical or solid-state meters, but require the adoption of more expensive and time-consuming digital techniques; recently, some new approaches for the definition of power quantities have been investigated. In this paper, a survey of the classical and innovative definitions is proposed, with the aim of summarize the different points of view outlined by the researchers. A case study of power factor correction in nonsinusoidal conditions is also presented, to give a numerical comparison about the power quantities measured according to the various approaches.

Introduction to PRO for energy conversion applications including an electric equivalent circuit

Pressure retarded osmosis (PRO) is a renewable energy conversion process with potential for sustainable power production. This study introduces this resource to the electrical engineering community and presents the first electric equivalent circuit of the process. This provides a useful tool for integrated osmotic power plant analysis and design. The model illustrates the influence of several important non-ideal effects on power output including concentration polarisation, spatial variation, and pressure drop. The dynamic influence of salt storage by water is also considered. The influence of feed and draw input currents and hydraulic load on power output are investigated and suggest that there is some operating point that will yield maximum power. This illustrates the need for maximum power point tracking in PRO energy conversion.

Investigations of vapour-phase deposited transition metal dichalcogenide films for future electronic applications

Two-dimensional (2D) transitional metal dichalcogenides (TMDs) are of major interest to the research and electrical engineering community. A number of TMDs are semiconducting and have a wide range of bandgaps, they can exhibit n- or p-type behaviour, and the electronic structure changes with the number of layers. These exceptional properties hold much promise for a host of electrical applications including low- or high power field-effect transistors, sensors and diodes. Moreover, the unique optical properties of TMDs make them attractive for optoelectronic applications such as light-emitting diodes, photodiodes, and photovoltaic cells. A prerequisite for all of these applications is a synthesis route which is well controlled, scalable, reproducible and compatible with semiconductor industry process flows. Thermally assisted conversion (TAC), a variant of chemical vapour deposition, shows much promise for meeting these requirements. Herein we review the current progress and challenges of research on 2D semiconducting materials for electronics with a special focus on TAC produced TMD thin films.

A Critical Review of Robustness in Power Grids Using Complex Networks Concepts

This paper reviews the most relevant works that have investigated robustness in power grids using Complex Networks (CN) concepts. In this broad field there are two different approaches. The first one is based solely on topological concepts, and uses metrics such as mean path length, clustering coefficient, efficiency and betweenness centrality, among many others. The second, hybrid approach consists of introducing (into the CN framework) some concepts from Electrical Engineering (EE) in the effort of enhancing the topological approach, and uses novel, more efficient electrical metrics such as electrical betweenness, net-ability, and others. There is however a controversy about whether these approaches are able to provide insights into all aspects of real power grids. The CN community argues that the topological approach does not aim to focus on the detailed operation, but to discover the unexpected emergence of collective behavior, while part of the EE community asserts that this leads to an excessive simplification. Beyond this open debate it seems to be no predominant structure (scale-free, small-world) in high-voltage transmission power grids, the vast majority of power grids studied so far. Most of them have in common that they are vulnerable to targeted attacks on the most connected nodes and robust to random failure. In this respect there are only a few works that propose strategies to improve robustness such as intentional islanding, restricted link addition, microgrids and Energies 2015, 8 9212 smart grids, for which novel studies suggest that small-world networks seem to be the best topology.

Domesticating electric power: Growth of industry, utilities and research in colonial Calcutta

Public electricity supplies became available in Calcutta as early as the 1890s and by the 1940s had developed to become the major source of power and lighting both for industries and private use. Could the electrification of Calcutta act as an agent of industrial development? What impact did it have on the socio-economic condition of the city? The twentieth century was to be the age of electricity. Apart from industrial use of this new technology, to realise its full practical capacities a new discipline emerged—electrical engineering. The Bengali electrical engineering community, alumni of Sibpur and Jadavpur Engineering Colleges, gradually oriented themselves towards ideas of industrial development based on Indian realities. Few trained electrical engineers entered in the business sector and became very successful. High level of technological innovation such as that of hydroelectricity was also exploited by the Bengali entrepreneurs. The credentials of the Bengali erudite and ordinary people in the field of electricity, which this article tries to explore, offer an interesting example of Indian response to the new knowledge.

The Automatization of Nikola Tesla: Thinking Invention in the Late Nineteenth Century

By investigating the conflicted relationship between Nikola Tesla (1856–1943) and the electrical engineering community, this essay explores competing representations of “invention” in the fin-de-siècle period. Drawing on the observation that the dominant paradigm of invention was entangled in various inscription practices, I turn to the case of Tesla to examine how inventions that circulated only as discourses were represented and legitimated in the scientific community, popular press, and literature. The essay argues that the rise of transmission media, such as wireless telegraphy, that challenged established conceptions about physical reality informed, in turn, Tesla’s singular model of invention.

Guest Editors' Introduction: Synthetic Biology

h SYNTHETIC BIOLOGY IS trending, as evidenced by the recent achievements in biofuels (microbial production of diesel fuels from fatty acids in Escherichia coli (E. coli) and yeast) and in biotherapeutics (microbial production of artemisnic acid as a viable source of antimalarial drugs). The International Genetically Engineered Machine (iGEM) competition in 2011 had over 165 teams and 1000+ undergraduate participants from around the world. Synthetic Biology had a global market which generated $233.8 million in 2008. This is expected to increase to $2.4 billion in 2013. Synthetic biology alone had a chemicals and energy segment worth $80.6 million in 2008 with a projected growth to $1.6 billion in 2013. Synthetic biology is here to stay. Handcrafted genetic circuits and pathways added to well characterized host organisms are one way produce new synthetic biological systems. These circuits and pathways are not easily identified nor readily constructed; they require extensive funding and research efforts spanning multiple years. ‘‘Design flows’’ are ad hoc, involving trial and error, and relying heavily on biologists’ intuition and experience. Recall ‘‘design compilers’’ that were dreams in the late 1970s or the ‘‘napkin-to-chip’’ concept in the 1990s? The equivalent conceptual dream in biology now is just beginning to be articulated in many bioengineering fields spanning synthetic biology, metabolic engineering, systems biology, and genetic engineering. The buzz phrasing has not arrived yet. ‘‘Bio Design Automation (BDA)’’ or ‘‘Genetic Design Automation (GDA)’’ promises to deliver the software infrastructure and support design methodologies spanning functional specification to manufacturing instructions. This special section of this issue of D&T brings together four articles and a perspective on software tools that aid in synthetic biological circuits and systems. ‘‘Design Automation for Synthetic Biological Systems’’ serves as a tutorial illustrating two complementary approaches to designing biology systems by either bottom-up, part-based genetic circuits or the modification of metabolic pathways. ‘‘Digital Signal Processing with Molecular Reactions’’ illustrates how biological systems can be abstracted into sets of reactions which can resemble processing systems familiar to the electrical engineering community. ‘‘Design and Test of Genetic Circuits using iBioSim’’ presents a software framework for the simulation of synthetic biological systems. Finally, ‘‘Fast Solvers for Biomolecular Science and Engineering’’ outlines mathematical frameworks which model the dynamics present in biological systems. Together these articles provide background material, modeling frameworks, and examples of software solutions. In addition to the four outlined articles, the ‘‘Last Byte’’ of this issue provides a humorous and fictitious take on the origins of BDA. ‘‘Perspectives’’ provides an examination of the emerging biodesign automation field alongside the early days of EDA.