Electronics

13 pages, 8109 KiB

Open AccessArticle

A Miniature Data Repository on a Raspberry Pi

by Argyrios Samourkasidis and Ioannis N. Athanasiadis^*

Information Technology Group, Wageningen University, Hollandseweg 1, Wageningen 6706 KN, The Netherlands

Electronics 2017, 6(1), 1; https://doi.org/10.3390/electronics6010001 - 28 Dec 2016

Cited by 8 | Viewed by 8909

Abstract

This work demonstrates a low-cost, miniature data repository proof-of-concept. Such a system needs to be resilient to power and network failures, and expose adequate processing power for persistent, long-term storage. Additional services are required for interoperable data sharing and visualization. We designed and [...] Read more.

This work demonstrates a low-cost, miniature data repository proof-of-concept. Such a system needs to be resilient to power and network failures, and expose adequate processing power for persistent, long-term storage. Additional services are required for interoperable data sharing and visualization. We designed and implemented a software tool called Airchive to run on a Raspberry Pi, in order to assemble a data repository for archiving and openly sharing timeseries data. Airchive employs a relational database for storing data and implements two standards for sharing data (namely the Sensor Observation Service by the Open Geospatial Consortium and the Protocol for Metadata Harvesting by the Open Archives Initiative). The system is demonstrated in a realistic indoor air pollution data acquisition scenario in a four-month experiment evaluating its autonomy and robustness under power and network disruptions. A stress test was also conducted to evaluate its performance against concurrent client requests. Full article

(This article belongs to the Special Issue Raspberry Pi Technology)

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14 pages, 763 KiB

Open AccessArticle

Resilience Evaluation of Demand Response as Spinning Reserve under Cyber-Physical Threats

by Anas AlMajali^1,*

, Arun Viswanathan²

and Clifford Neuman²

¹ Department of Computer Engineering, The Hashemite University, Zarqa 13133, Jordan

² Information Sciences Institute, University of Southern California, Los Angeles, CA 90089, USA

Electronics 2017, 6(1), 2; https://doi.org/10.3390/electronics6010002 - 28 Dec 2016

Cited by 11 | Viewed by 6773

Abstract

In the future, automated demand response mechanisms will be used as spinning reserve. Demand response in the smart grid must be resilient to cyber-physical threats. In this paper, we evaluate the resilience of demand response when used as spinning reserve in the presence [...] Read more.

In the future, automated demand response mechanisms will be used as spinning reserve. Demand response in the smart grid must be resilient to cyber-physical threats. In this paper, we evaluate the resilience of demand response when used as spinning reserve in the presence of cyber-physical threats. We quantify this evaluation by correlating the stability of the system in the presence of attacks measured by system frequency (Hz) and attack level measured by the amount of load (MW) that responds to the demand response event. The results demonstrate the importance of anticipating the dependability of demand response before it can be relied upon as spinning reserve. Full article

(This article belongs to the Special Issue Smart Grid Cyber Security)

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12 pages, 322 KiB

Open AccessArticle

A Compressive-Sensing Inspired Alternate Projection Algorithm for Sparse Array Synthesis

by Daniele Pinchera^*

, Marco Donald Migliore

, Mario Lucido

, Fulvio Schettino and Gaetano Panariello

DIEI—Dipartimento di Ingegneria Elettrica e dell’Informazione, University of Cassino and Southern Lazio, via G. Di Biasio 43, 03043 Cassino, Italy

Electronics 2017, 6(1), 3; https://doi.org/10.3390/electronics6010003 - 28 Dec 2016

Cited by 23 | Viewed by 6234

Abstract

In this paper, we propose a simple approach for sparse array synthesis. We employ a modified generalized alternate projection algorithm using

ℓ_{1}

-norm constrained minimization in order to achieve the excitation and the position of the elements of a sparse array. The [...] Read more.

In this paper, we propose a simple approach for sparse array synthesis. We employ a modified generalized alternate projection algorithm using

ℓ_{1}

-norm constrained minimization in order to achieve the excitation and the position of the elements of a sparse array. The proposed approach is very flexible, since it deals with power pattern masks and allows the inclusion of the effects of element pattern and mutual coupling. Its implementation is relatively simple, thanks to the possibility to use well-known convex programming techniques. The presented method is particularly suitable for the synthesis of patterns commonly employed in radar systems; the numerical results provided show good performances with respect to concurrent methods available in open literature. Full article

(This article belongs to the Special Issue Radio and Radar Signal Processing)

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9 pages, 553 KiB

Open AccessArticle

A Novel Channel Coding Scheme for RFID Generation-2 Systems

by Emanuele Goldoni^*

, Pietro Savazzi

and Anna Vizziello

Dipartimento di Ingegneria Industriale e dell’Informazione, University of Pavia, 27100 Pavia, Italy

Electronics 2017, 6(1), 4; https://doi.org/10.3390/electronics6010004 - 30 Dec 2016

Cited by 1 | Viewed by 6489

Abstract

Low complexity and efficient algorithms for Radio-Frequency Identification (RFID) are crucial to foster low-cost and energy-saving solutions. With the aim of lowering the complexity of the radio circuitry, and inspired by the superposition codes concept, we propose a novel encoding algorithm for tag-to-reader [...] Read more.

Low complexity and efficient algorithms for Radio-Frequency Identification (RFID) are crucial to foster low-cost and energy-saving solutions. With the aim of lowering the complexity of the radio circuitry, and inspired by the superposition codes concept, we propose a novel encoding algorithm for tag-to-reader communication channels of modern RFID systems. We show that the developed scheme—despite the simplicity of its hardware realization—allows a coding gain comparable to the one obtained by the more complex Viterbi decoding of the Miller 4 modulation scheme used in the EPC Generation 2 Class 1 RFID standard. Simulation results prove the effectiveness of the proposed solution for low-cost tags, under different signal-to-noise ratios (SNRs) and interrogation time durations. Although our numerical evaluation mainly focuses on the EPC Generation-2 standard, we believe that the proposed scheme will also be attractive for future Ultra-wideband RFID systems. Full article

(This article belongs to the Special Issue RFID Systems and Applications)

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22 pages, 1806 KiB

Open AccessReview

Wireless Sensor Network Based Smart Grid Communications: Cyber Attacks, Intrusion Detection System and Topology Control

by Lipi Chhaya^1,*

, Paawan Sharma¹

, Govind Bhagwatikar² and Adesh Kumar¹

¹ Department of Electronics, Instrumentation and Control Engineering, University of Petroleum & Energy Studies, Dehradun 248007, India

² Wind & Solar Energy, SANY Group, Pune 410501, India

Electronics 2017, 6(1), 5; https://doi.org/10.3390/electronics6010005 - 4 Jan 2017

Cited by 106 | Viewed by 17004

Abstract

The existing power grid is going through a massive transformation. Smart grid technology is a radical approach for improvisation in prevailing power grid. Integration of electrical and communication infrastructure is inevitable for the deployment of Smart grid network. Smart grid technology is characterized [...] Read more.

The existing power grid is going through a massive transformation. Smart grid technology is a radical approach for improvisation in prevailing power grid. Integration of electrical and communication infrastructure is inevitable for the deployment of Smart grid network. Smart grid technology is characterized by full duplex communication, automatic metering infrastructure, renewable energy integration, distribution automation and complete monitoring and control of entire power grid. Wireless sensor networks (WSNs) are small micro electrical mechanical systems that are deployed to collect and communicate the data from surroundings. WSNs can be used for monitoring and control of smart grid assets. Security of wireless sensor based communication network is a major concern for researchers and developers. The limited processing capabilities of wireless sensor networks make them more vulnerable to cyber-attacks. The countermeasures against cyber-attacks must be less complex with an ability to offer confidentiality, data readiness and integrity. The address oriented design and development approach for usual communication network requires a paradigm shift to design data oriented WSN architecture. WSN security is an inevitable part of smart grid cyber security. This paper is expected to serve as a comprehensive assessment and analysis of communication standards, cyber security issues and solutions for WSN based smart grid infrastructure. Full article

(This article belongs to the Special Issue Smart Grid Cyber Security)

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9 pages, 725 KiB

Open AccessArticle

The Implementation of a High-Frequency Radio Frequency Identification System with a Battery-Free Smart Tag for Orientation Monitoring

by Tilen Svete^*, Nejc Suhadolnik and Anton Pleteršek

STMicroelectronics d.o.o., Tehnološki Park 21, 1000 Ljubljana, Slovenia

Electronics 2017, 6(1), 6; https://doi.org/10.3390/electronics6010006 - 4 Jan 2017

Cited by 3 | Viewed by 6631

Abstract

Energy-harvesting passive RFID (radio frequency identification) tags provide countless possibilities as so-called smart tags. Smart tags can communicate with existing RFID readers or interrogators while providing a battery-less platform for internal and external sensors to enrich available information about the environment and smart [...] Read more.

Energy-harvesting passive RFID (radio frequency identification) tags provide countless possibilities as so-called smart tags. Smart tags can communicate with existing RFID readers or interrogators while providing a battery-less platform for internal and external sensors to enrich available information about the environment and smart tag it. A reduced cost and size as well as an increased lifespan and durability of battery-free smart tags offer improvements in areas such as transportation and product tracking. Battery-free smart tags can ideally support arbitrarily complex sensor measurements, but in reality energy limitations can introduce great reductions in operating range and thus application range. In this work, we present an example application of a smart tag with a passive HF (high-frequency) RFID tag IC (integrated circuit) and MEMS (micro electro-mechanical structure) sensor. A standard HF RFID reader connected to a PC (personal computer) allowed the RF (radio frequency) field to power and communicate with the smart tag. A Kalman filter, implemented on a PC, was used to correct and improve the raw sensor data of smart tag orientation. Measurement results showed that the MEMS sensor on the smart tag could be powered for continuous operation and that raw smart tag orientation data could be read while in the RF field of a standard HF RFID reader, but at a limited range. Full article

(This article belongs to the Special Issue RFID Systems and Applications)

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17 pages, 2213 KiB

Open AccessArticle

High-Speed Non-Volatile Optical Memory: Achievements and Challenges

by Vadym Zayets

Spintronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568, Japan

Electronics 2017, 6(1), 7; https://doi.org/10.3390/electronics6010007 - 10 Jan 2017

Cited by 7 | Viewed by 9766

Abstract

We have proposed, fabricated, and studied a new design of a high-speed optical non-volatile memory. The recoding mechanism of the proposed memory utilizes a magnetization reversal of a nanomagnet by a spin-polarized photocurrent. It was shown experimentally that the operational speed of this [...] Read more.

We have proposed, fabricated, and studied a new design of a high-speed optical non-volatile memory. The recoding mechanism of the proposed memory utilizes a magnetization reversal of a nanomagnet by a spin-polarized photocurrent. It was shown experimentally that the operational speed of this memory may be extremely fast above 1 TBit/s. The challenges to realize both a high-speed recording and a high-speed reading are discussed. The memory is compact, integratable, and compatible with present semiconductor technology. If realized, it will advance data processing and computing technology towards a faster operation speed. Full article

(This article belongs to the Special Issue Spin Optoelectronics)

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4 pages, 158 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Electronics in 2016

by Electronics Editorial Office

MDPI AG, St. Alban-Anlage 66, 4052 Basel, Switzerland

Electronics 2017, 6(1), 8; https://doi.org/10.3390/electronics6010008 - 12 Jan 2017

Viewed by 4587

Abstract

The editors of Electronics would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...] Full article

8 pages, 2811 KiB

Open AccessArticle

A Modular Integrated RFID System for Inventory Control Applications

by Ross Bunker and Atef Elsherbeni^*

Electrical Engineering and Computer Science Department, Colorado School of Mines, Golden, CO 80401, USA

Electronics 2017, 6(1), 9; https://doi.org/10.3390/electronics6010009 - 12 Jan 2017

Cited by 15 | Viewed by 9569

Abstract

Recent advances in single-board computer technology have allowed for lightweight, power-efficient devices, such as the Raspberry Pi, to take the place of desktop PCs in certain applications. This has the potential to disrupt the way many current systems are structured, particularly for inventory [...] Read more.

Recent advances in single-board computer technology have allowed for lightweight, power-efficient devices, such as the Raspberry Pi, to take the place of desktop PCs in certain applications. This has the potential to disrupt the way many current systems are structured, particularly for inventory management and control applications. In this paper, we explore the design and topology of a modular Radio frequency identification (RFID) system for inventory management comprised of self-contained, autonomous scanning, and stationary control PCs in a handheld/portable configuration. While similar solutions for such a system may exist on the commercial market, this proposed development provides a template for an open source flexible, low-cost solution that can be easily expanded to meet the needs of businesses with large and small inventories. Full article

(This article belongs to the Special Issue RFID Systems and Applications)

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23 pages, 4918 KiB

Open AccessArticle

Obstacle Avoidance Based-Visual Navigation for Micro Aerial Vehicles

by Wilbert G. Aguilar^1,2,3,*

, Verónica P. Casaliglla^4,* and José L. Pólit^4,*

¹ Centro de Investigación Científica y Tecnológica del Ejército CICTE, Universidad de las Fuerzas Armadas ESPE, Sangolqui 171103, Ecuador

² Departamento de Seguridad y Defensa, Universidad de las Fuerzas Armadas ESPE, Sangolqui 171103, Ecuador

³ Research Group on Knowledge Engineering GREC, Universitat Politècnica de Catalunya UPC-BarcelonaTech, Barcelona 08040, Spain

⁴ Departamento de Eléctrica y Electrónica DEEE, Universidad de las Fuerzas Armadas ESPE, Sangolqui 171103, Ecuador

Electronics 2017, 6(1), 10; https://doi.org/10.3390/electronics6010010 - 19 Jan 2017

Cited by 80 | Viewed by 12838

Abstract

This paper describes an obstacle avoidance system for low-cost Unmanned Aerial Vehicles (UAVs) using vision as the principal source of information through the monocular onboard camera. For detecting obstacles, the proposed system compares the image obtained in real time from the UAV with [...] Read more.

This paper describes an obstacle avoidance system for low-cost Unmanned Aerial Vehicles (UAVs) using vision as the principal source of information through the monocular onboard camera. For detecting obstacles, the proposed system compares the image obtained in real time from the UAV with a database of obstacles that must be avoided. In our proposal, we include the feature point detector Speeded Up Robust Features (SURF) for fast obstacle detection and a control law to avoid them. Furthermore, our research includes a path recovery algorithm. Our method is attractive for compact MAVs in which other sensors will not be implemented. The system was tested in real time on a Micro Aerial Vehicle (MAV), to detect and avoid obstacles in an unknown controlled environment; we compared our approach with related works. Full article

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13 pages, 4259 KiB

Open AccessArticle

Ground-Based 3D Radar Imaging of Trees Using a 2D Synthetic Aperture

by Justin F. Penner and David G. Long^*

Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84602, USA

Electronics 2017, 6(1), 11; https://doi.org/10.3390/electronics6010011 - 23 Jan 2017

Cited by 14 | Viewed by 9732

Abstract

Motivated by the desire to gain insight into the details of conventional airborne synthetic aperture radar (SAR) imaging of trees, a ground-based SAR system designed for short-range three-dimensional (3D) radar imaging is developed using a two-dimensional (2D) synthetic aperture. The heart of the [...] Read more.

Motivated by the desire to gain insight into the details of conventional airborne synthetic aperture radar (SAR) imaging of trees, a ground-based SAR system designed for short-range three-dimensional (3D) radar imaging is developed using a two-dimensional (2D) synthetic aperture. The heart of the system is a compact linear frequency modulation-continuous wave (LFM-CW) radar, a custom two-dimensional scan mechanism, and a three-dimensional time-domain backprojection algorithm that generates three-dimensional backscatter images at an over-sampled resolution of 10 cm by 10 cm by 10 cm. The backprojection algorithm is formulated directly in spatial coordinates. A new method for estimating and compensating for signal attenuation within the canopy is used that exploits the backprojection image formation approach. Several three-dimensional C-band backscatter images of different individual trees of multiple species are generated from data collected for trees both in isolation and near buildings. The trees imaged in this study are about 10 m in height. The transformation of the three-dimensional images to airborne SAR images is described and a sample result provided. Full article

(This article belongs to the Special Issue Radio and Radar Signal Processing)

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4 pages, 148 KiB

Open AccessEditorial

Recent Advances on Wearable Electronics and Embedded Computing Systems for Biomedical Applications

by Enzo Pasquale Scilingo and Gaetano Valenza^*

Bioengineering and Robotics Research Centre “E. Piaggio”, and Department of Information Engineering, School of Engineering, University of Pisa, Largo Lucio Lazzarino 1, 56122 Pisa, Italy

Electronics 2017, 6(1), 12; https://doi.org/10.3390/electronics6010012 - 24 Jan 2017

Cited by 18 | Viewed by 6446

Abstract

The application of wearable electronics in the biomedical research and commercial ﬁelds has been gaining great interest over the last several decades.[...] Full article

(This article belongs to the Special Issue Wearable Electronics and Embedded Computing Systems for Biomedical Applications)

19 pages, 1630 KiB

Open AccessArticle

Sudoku Inspired Designs for Radar Waveforms and Antenna Arrays

by Travis D. Bufler¹, Ram M. Narayanan^1,*

and Kelly D. Sherbondy²

¹ Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802, USA

² Sensors and Electronics Directorate, U.S. Army Research Laboratory, Adelphi, MD 20783, USA

Electronics 2017, 6(1), 13; https://doi.org/10.3390/electronics6010013 - 8 Feb 2017

Cited by 9 | Viewed by 7258

Abstract

Sudoku puzzles, often seen in magazines and newspapers, are logic-based challenges where each entry within the puzzle is comprised of symbols adhering to row, column and box constraints. Previously, we had investigated their potential in frequency-hopped waveforms to achieve desirable radar ambiguity functions [...] Read more.

Sudoku puzzles, often seen in magazines and newspapers, are logic-based challenges where each entry within the puzzle is comprised of symbols adhering to row, column and box constraints. Previously, we had investigated their potential in frequency-hopped waveforms to achieve desirable radar ambiguity functions and compared them with random, as well as the more familiar Costas sequences. This paper further examines the properties of Sudoku codes in more detail through computational search and analysis. We examine the co-hit and cross-hit arrays, defined as the correlation between two sequences, to quickly and efficiently evaluate numerous Sudoku puzzles. Additionally, we investigate the use of Sudoku puzzles for antenna applications, including array interleaving, array thinning and random element spacing. Full article

(This article belongs to the Special Issue Radio and Radar Signal Processing)

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11 pages, 3684 KiB

Open AccessArticle

Object‐Oriented RFID with IoT: A Design Concept of Information Systems in Manufacturing

by Tamotsu Kamigaki

Faculty of Information Design and Sociology, Hiroshima Kokusai Gakuin University, Hiroshima 739‐0321, Japan

Electronics 2017, 6(1), 14; https://doi.org/10.3390/electronics6010014 - 8 Feb 2017

Cited by 38 | Viewed by 8238

Abstract

The Internet of Things (IoT) has increasingly become important in industry. Connectivity over the internet of not only people but also devices (such as sensors, appliances, machines, robots, and vehicles) is leading to a paradigm shift in manufacturing. The Japanese government recognizes this [...] Read more.

The Internet of Things (IoT) has increasingly become important in industry. Connectivity over the internet of not only people but also devices (such as sensors, appliances, machines, robots, and vehicles) is leading to a paradigm shift in manufacturing. The Japanese government recognizes this and has stated that IoT connectivity and the methodologies to exploit it are paramount for Japanese industry. Currently, the necessary changes have been realized in large Japanese companies; however, implementation in smaller companies has been lagging, despite the advantages of introducing IoT technologies, due to the high cost. The objective of this research is to suggest a design concept which combines IoT and object‐oriented radio frequency identification (RFID). IoT technology is used for collecting, analyzing, and managing data, and an object‐oriented RFID system is used as a control process in manufacturing systems. In previous research, the objectoriented RFID system was shown to provide flexible management through the use of a variety of OORFID tags. The current research extends this by introducing object‐oriented RFID into IoT systems to improve the flexibility in the manufacturing systems. For the verification of this concept, an experimental IoT system using object‐oriented RFID was designed and implemented Full article

(This article belongs to the Special Issue RFID Systems and Applications)

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18 pages, 2120 KiB

Open AccessArticle

Coupled GPS/MEMS IMU Attitude Determination of Small UAVs with COTS

by Michael Strohmeier^* and Sergio Montenegro

Chair of Aerospace Information Technology, Julius-Maximillians-Universität Würzburg, Josef-Martin-Weg, 97074 Würzburg, Germany

Electronics 2017, 6(1), 15; https://doi.org/10.3390/electronics6010015 - 10 Feb 2017

Cited by 18 | Viewed by 9707

Abstract

This paper proposes an attitude determination system for small Unmanned Aerial Vehicles (UAV) with a weight limit of 5 kg and a small footprint of 0.5m x 0.5 m. The system is realized by coupling single-frequency Global Positioning System (GPS) code and carrier-phase [...] Read more.

This paper proposes an attitude determination system for small Unmanned Aerial Vehicles (UAV) with a weight limit of 5 kg and a small footprint of 0.5m x 0.5 m. The system is realized by coupling single-frequency Global Positioning System (GPS) code and carrier-phase measurements with the data acquired from a Micro-Electro-Mechanical System (MEMS) Inertial Measurement Unit (IMU) using consumer-grade Components-Off-The-Shelf (COTS) only. The sensor fusion is accomplished using two Extended Kalman Filters (EKF) that are coupled by exchanging information about the currently estimated baseline. With a baseline of 48 cm, the static heading accuracy of the proposed system is comparable to the one of a commercial single-frequency GPS heading system with an accuracy of approximately 0.25°/m. Flight testing shows that the proposed system is able to obtain a reliable and stable GPS heading estimation without an aiding magnetometer. Full article

(This article belongs to the Special Issue Unmanned Aerial Systems/Vehicles (UAS/V) and Drones)

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20 pages, 2922 KiB

Open AccessArticle

E²LEMI:Energy-Efficient Logic Encryption Using Multiplexer Insertion

by Qutaiba Alasad, Yu Bi and Jiann-Shuin Yuan^*

Department of Electrical and Computer Engineering, University of Central Florida, Orlando, FL 32816, USA

Electronics 2017, 6(1), 16; https://doi.org/10.3390/electronics6010016 - 15 Feb 2017

Cited by 20 | Viewed by 6811

Abstract

Due to the outsourcing of chip manufacturing, countermeasures against Integrated Circuit (IC) piracy, reverse engineering, IC overbuilding and hardware Trojans (HTs) become a hot research topic. To protect an IC from these attacks, logic encryption techniques have been considered as a low-cost defense [...] Read more.

Due to the outsourcing of chip manufacturing, countermeasures against Integrated Circuit (IC) piracy, reverse engineering, IC overbuilding and hardware Trojans (HTs) become a hot research topic. To protect an IC from these attacks, logic encryption techniques have been considered as a low-cost defense mechanism. In this paper, our proposal is to insert the multiplexer (MUX) with two cases: (i) we randomly insert MUXs equal to half of the output bit number (half MUX insertions); and (ii) we insert MUXs equal to the number of output bits (full MUX insertions). Hamming distance is adopted as a security evaluation. We also measure the delay, power and area overheads with the proposed technique. Full article

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22 pages, 3605 KiB

Open AccessFeature PaperArticle

SmartContent—Self-Protected Context-Aware Active Documents for Mobile Environments

by Francesco Luca De Angelis^*

and Giovanna Di Marzo Serugendo

Institute of Services Science, University of Geneva, Route de Drize 7, CH-1227 Carouge, Switzerland

Electronics 2017, 6(1), 17; https://doi.org/10.3390/electronics6010017 - 4 Mar 2017

Cited by 5 | Viewed by 6148

Abstract

Mobile devices make it possible to create, store, access, share or publish personal content on the Internet, anywhere and at anytime. This leads to situations of potential intentional or unintentional misuse of content as well as privacy issues. Recent techniques involving the use [...] Read more.

Mobile devices make it possible to create, store, access, share or publish personal content on the Internet, anywhere and at anytime. This leads to situations of potential intentional or unintentional misuse of content as well as privacy issues. Recent techniques involving the use of contextual information focus on access of documents stored in clouds, or authentication for secured Web sites. These techniques or more traditional solutions, such as steganography or Digital Rights Management, do not empower the user itself, or data controller in professional settings, with a fine-grained control of the access to or manipulations actions on documents stored on mobile devices, e.g., copying, sharing, etc. In this paper, we propose SmartContent, a novel approach for content protection and privacy. Documents are active and context-aware documents that sense and analyse their current context, e.g., location, noise, neighbouring devices, social network, expiration time, etc. Based on user provided policies, they grant, deny or limit access and manipulation actions, or destroy themselves if necessary. We present the generic model of SmartContent, a concrete architecture and an implementation of a proof-of-concept specifically designed for mobile devices. We deployed it on tablets and showed that a picture dynamically reveals or conceals itself based on sensed context or on changing policies. The implementation leverages the SAPERE middleware specifically developed for context-aware systems. Full article

(This article belongs to the Special Issue Security and Privacy in Mobile Systems)

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13 pages, 2708 KiB

Open AccessArticle

Exploring FPGA‐Based Lock‐In Techniques for Brain Monitoring Applications

by Giuseppe Costantino Giaconia^*

, Giuseppe Greco, Leonardo Mistretta and Raimondo Rizzo

Laboratorio di Elettronica dei Sistemi Digitali Programmabili (ESDP Lab), Dipartimento di Energia, Ingegneria dell’informazione e Modelli matematici (DEIM), Università di Palermo, Viale delle Scienze (Bldg. 9), Palermo 90128, Italy

Electronics 2017, 6(1), 18; https://doi.org/10.3390/electronics6010018 - 2 Mar 2017

Cited by 21 | Viewed by 8502

Abstract

Functional near‐infrared spectroscopy (fNIRS) systems for e‐health applications usually suffer from poor signal detection, mainly due to a low end‐to‐end signal‐to‐noise ratio of the electronics chain. Lock‐in amplifiers (LIA) historically represent a powerful technique helping to improve performance in such circumstances. In this [...] Read more.

Functional near‐infrared spectroscopy (fNIRS) systems for e‐health applications usually suffer from poor signal detection, mainly due to a low end‐to‐end signal‐to‐noise ratio of the electronics chain. Lock‐in amplifiers (LIA) historically represent a powerful technique helping to improve performance in such circumstances. In this work a digital LIA system, based on a Zynq® field programmable gate array (FPGA) has been designed and implemented, in an attempt to explore if this technique might improve fNIRS system performance. More broadly, FPGA‐based solution flexibility has been investigated, with particular emphasis applied to digital filter parameters, needed in the digital LIA, and its impact on the final signal detection and noise rejection capability has been evaluated. The realized architecture was a mixed solution between VHDL hardware modules and software modules, running within a microprocessor. Experimental results have shown the goodness of the proposed solutions and comparative details among different implementations will be detailed. Finally a key aspect taken into account throughout the design was its modularity, allowing an easy increase of the input channels while avoiding the growth of the design cost of the electronics system. Full article

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25 pages, 1445 KiB

Open AccessFeature PaperReview

Progress towards Spin-Based Light Emission in Group IV Semiconductors

by Sebastiano De Cesari^*

, Elisa Vitiello^*

, Anna Giorgioni and Fabio Pezzoli

LNESS and Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca, via Cozzi 55, I-20125 Milano, Italy

Electronics 2017, 6(1), 19; https://doi.org/10.3390/electronics6010019 - 7 Mar 2017

Cited by 15 | Viewed by 8148

Abstract

Spin-optoelectronics is an emerging technology in which novel and advanced functionalities are enabled by the synergetic integration of magnetic, optical and electronic properties onto semiconductor-based devices. This article reviews the possible implementation and convergence of spintronics and photonics concepts on group IV semiconductors: [...] Read more.

Spin-optoelectronics is an emerging technology in which novel and advanced functionalities are enabled by the synergetic integration of magnetic, optical and electronic properties onto semiconductor-based devices. This article reviews the possible implementation and convergence of spintronics and photonics concepts on group IV semiconductors: the core materials of mainstream microelectronics. In particular, we describe the rapid pace of progress in the achievement of lasing action in the notable case of Ge-based heterostructures and devote special attention to the pivotal role played by optical investigations in advancing the understanding of the rich spin physics of group IV materials. Finally, we scrutinize recent developments towards the monolithic integration on Si of a new class of spin-based light emitting devices having prospects for applications in fields such as cryptography and interconnects. Full article

(This article belongs to the Special Issue Spin Optoelectronics)

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9 pages, 899 KiB

Open AccessFeature PaperArticle

Knowledge-Aided Covariance Matrix Estimation in Spiky Radar Clutter Environments

by Jeong H. Bang¹, William L. Melvin^2,* and Aaron D. Lanterman¹

¹ School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA

² Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, GA 30332, USA

Electronics 2017, 6(1), 20; https://doi.org/10.3390/electronics6010020 - 9 Mar 2017

Cited by 3 | Viewed by 5530

Abstract

Space-time adaptive processing (STAP) is an important airborne radar technique used to improve target detection in clutter-limited environments. Effective STAP implementation is dependent on accurate space-time covariance matrix estimation. Heterogeneous clutter, including spiky, spatial clutter variation, violates underlying STAP training assumptions and can [...] Read more.

Space-time adaptive processing (STAP) is an important airborne radar technique used to improve target detection in clutter-limited environments. Effective STAP implementation is dependent on accurate space-time covariance matrix estimation. Heterogeneous clutter, including spiky, spatial clutter variation, violates underlying STAP training assumptions and can significantly degrade corresponding detection performance. This paper develops a spiky, space-time clutter model based on the K-distribution, assesses the resulting impact on STAP performance using traditional methods, and then proposes and evaluates the utility of the knowledge-aided parametric covariance matrix estimation (KAPE) method, a model-based scheme that rapidly converges to better represent spatial variation in clutter properties. Via numerical simulation of an airborne radar scenario operating in a spiky clutter environment, we find substantial improvement in probability of detection (

P_{D}

) for a fixed probability of false alarm (

P_{F A}

) for the KAPE method. For example, in the spiky clutter environment considered herein, results indicate a

P_{D}

of 32% for traditional STAP and in excess of 90% for KAPE at a

P_{F A}

of 1E-4, with a corresponding difference of 11.5 dB in threshold observed from exceedance analysis. The proposed K-distributed spiky clutter model, and application and assessment of KAPE as an ameliorating STAP technique, contribute to an improved understanding of radar detection in complex clutter environments. Full article

(This article belongs to the Special Issue Radio and Radar Signal Processing)

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29 pages, 1258 KiB

Open AccessArticle

Compressed Sensing ISAR Reconstruction Considering Highly Maneuvering Motion

by Ahmed Shaharyar Khwaja^* and Mujdat Cetin

Faculty of Engineering and Natural Sciences, Sabanci University, Tuzla, Istanbul 34956, Turkey

Electronics 2017, 6(1), 21; https://doi.org/10.3390/electronics6010021 - 11 Mar 2017

Cited by 11 | Viewed by 6284

Abstract

In this report, we propose compressed sensing inverse synthetic aperture radar (ISAR) imaging in the presence of highly maneuvering motion using a modified orthogonal matching pursuit (OMP) reconstruction algorithm. Unlike existing methods where motion is limited to first- or second-order phase terms, we [...] Read more.

In this report, we propose compressed sensing inverse synthetic aperture radar (ISAR) imaging in the presence of highly maneuvering motion using a modified orthogonal matching pursuit (OMP) reconstruction algorithm. Unlike existing methods where motion is limited to first- or second-order phase terms, we take into account realistic motion of a maneuvering target that can involve a third-order phase term corresponding to the rate of rotational acceleration. In addition, unlike existing fixed dictionary-based methods, which require designing a large dictionary that needs to take into account all of the possible motion parameters, we propose a modified OMP reconstruction method that requires a dictionary only based on the first-order phase term and estimates the secondand third-order phase terms using an optimization algorithm. Simulation examples and comparison with existing methods show the viability of our approach for imaging moving targets consisting of higher order motion. Full article

(This article belongs to the Special Issue Radio and Radar Signal Processing)

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10 pages, 1959 KiB

Open AccessArticle

Real-Time and High-Accuracy Arctangent Computation Using CORDIC and Fast Magnitude Estimation

by Luca Pilato, Luca Fanucci and Sergio Saponara^*

Dipartimento Ingegneria della Informazione, Università di Pisa, via G. Caruso 16, 56122 Pisa, Italy

Electronics 2017, 6(1), 22; https://doi.org/10.3390/electronics6010022 - 16 Mar 2017

Cited by 19 | Viewed by 7368

Abstract

This paper presents an improved VLSI (Very Large Scale of Integration) architecture for real-time and high-accuracy computation of trigonometric functions with fixed-point arithmetic, particularly arctangent using CORDIC (Coordinate Rotation Digital Computer) and fast magnitude estimation. The standard CORDIC implementation suffers of a loss [...] Read more.

This paper presents an improved VLSI (Very Large Scale of Integration) architecture for real-time and high-accuracy computation of trigonometric functions with fixed-point arithmetic, particularly arctangent using CORDIC (Coordinate Rotation Digital Computer) and fast magnitude estimation. The standard CORDIC implementation suffers of a loss of accuracy when the magnitude of the input vector becomes small. Using a fast magnitude estimator before running the standard algorithm, a pre-processing magnification is implemented, shifting the input coordinates by a proper factor. The entire architecture does not use a multiplier, it uses only shift and add primitives as the original CORDIC, and it does not change the data path precision of the CORDIC core. A bit-true case study is presented showing a reduction of the maximum phase error from 414 LSB (angle error of 0.6355 rad) to 4 LSB (angle error of 0.0061 rad), with small overheads of complexity and speed. Implementation of the new architecture in 0.18 µm CMOS technology allows for real-time and low-power processing of CORDIC and arctangent, which are key functions in many embedded DSP systems. The proposed macrocell has been verified by integration in a system-on-chip, called SENSASIP (Sensor Application Specific Instruction-set Processor), for position sensor signal processing in automotive measurement applications. Full article

(This article belongs to the Special Issue Real-Time Embedded Systems)

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6 pages, 1237 KiB

Open AccessArticle

The Recovery of a Magnetically Dead Layer on the Surface of an Anatase (Ti,Co)O₂ Thin Film via an Ultrathin TiO₂ Capping Layer

by Thantip S. Krasienapibal¹, Tomoteru Fukumura^2,*

and Tetsuya Hasegawa³

¹ Department of Chemistry, The University of Tokyo, Tokyo 113-0033, Japan

² WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Department of Chemistry, Tohoku University, Sendai 980-8578, and Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan

³ Department of Chemistry, The University of Tokyo, Tokyo 113-0033, and Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012, Japan

Electronics 2017, 6(1), 23; https://doi.org/10.3390/electronics6010023 - 18 Mar 2017

Cited by 3 | Viewed by 6171

Abstract

The effect of an ultrathin TiO₂ capping layer on an anatase Ti_0.95Co_0.05O_2−δ (001) epitaxial thin film on magnetism at 300 K was investigated. Films with a capping layer showed increased magnetization mainly caused by enhanced out-of-plane magnetization. [...] Read more.

The effect of an ultrathin TiO₂ capping layer on an anatase Ti_0.95Co_0.05O_2−δ (001) epitaxial thin film on magnetism at 300 K was investigated. Films with a capping layer showed increased magnetization mainly caused by enhanced out-of-plane magnetization. In addition, the ultrathin capping layer was useful in prolonging the magnetization lifetime by more than two years. The thickness dependence of the magnetic domain structure at room temperature indicated the preservation of magnetic domain structure even for a 13 nm thick film covered with a capping layer. Taking into account nearly unchanged electric conductivity irrespective of the capping layer’s thickness, the main role of the capping layer is to prevent surface oxidation, which reduces electron carriers on the surface. Full article

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Electronics, Volume 6, Issue 1 (March 2017) – 24 articles

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