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

An approach for using a Genetic Algorithm (GA) to select radar design parameters related to beamforming and angle of arrival estimation is presented in this article. This was accomplished by first developing a simulator that could evaluate the localization performance with a given set of design parameters. The simulator output was utilized as part of the GA objective function that searched the solution space for an optimal set of design parameters. Using this approach, the authors were able to more than halve the mean squared error in degrees of the localization algorithm versus a radar design using human-selected design parameters. The results of this study indicate that this kind of approach can be used to aid in the development of an actual radar design. Full article

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

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

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

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 ( $P_{FA}$ ) 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 $P_{FA}$ 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

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

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

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

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

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

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

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

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 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

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

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

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

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

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

In this paper, we propose a simple approach for sparse array synthesis. We employ a modified generalized alternate projection algorithm using ${\ell }_1$ -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

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 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