A Software-based Low-Jitter Servo Clock for Inexpensive Phasor Measurement Units

This paper presents the design and the implementation of a servo-clock (SC) for low-cost Phasor Measurement Units (PMUs). The SC relies on a classic Proportional Integral (PI) controller, which has been properly tuned to minimize the synchronization error due to the local oscillator triggering the on-board timer. The SC has been implemented into a PMU prototype developed within the OpenPMU project using a BeagleBone Black (BBB) board. The distinctive feature of the proposed solution is its ability to track an input Pulse-Per-Second (PPS) reference with good long-term stability and with no need for specific on-board synchronization circuitry. Indeed, the SC implementation relies only on one co-processor for real-time application and requires just an input PPS signal that could be distributed from a single substation clock

Flora Health Wireless Monitoring with Plant-Microbial Fuel Cell

Abstract We propose a self-sustainable wireless sensor node capable to monitor both environmental data and flora health state, exploiting a Microbial Fuel Cell combined with a plant. This bio-electrochemical system is used both as a power generator to supply the wireless embedded electronics and as a biosensor for estimating the status of the plant. We demonstrate that the sub-milliwatt power provided by the fuel cell is enough for achieving an energy-neutral smart sensor that samples and sends data. Moreover, the rate of the harvested power is correlated with the health of the flora living in symbiosis with the bacteria colony. The proposed system has been conceived to address the needs of future smart agriculture applications, providing an unobtrusive and energy neutral monitoring system open to a broad range of applications, thanks to the bacteria species that populate almost any soil on Earth

Genetic correlation between amyotrophic lateral sclerosis and schizophrenia

A. Palotie on työryhmän Schizophrenia Working Grp Psychiat jäsen.We have previously shown higher-than-expected rates of schizophrenia in relatives of patients with amyotrophic lateral sclerosis (ALS), suggesting an aetiological relationship between the diseases. Here, we investigate the genetic relationship between ALS and schizophrenia using genome-wide association study data from over 100,000 unique individuals. Using linkage disequilibrium score regression, we estimate the genetic correlation between ALS and schizophrenia to be 14.3% (7.05-21.6; P = 1 x 10(-4)) with schizophrenia polygenic risk scores explaining up to 0.12% of the variance in ALS (P = 8.4 x 10(-7)). A modest increase in comorbidity of ALS and schizophrenia is expected given these findings (odds ratio 1.08-1.26) but this would require very large studies to observe epidemiologically. We identify five potential novel ALS-associated loci using conditional false discovery rate analysis. It is likely that shared neurobiological mechanisms between these two disorders will engender novel hypotheses in future preclinical and clinical studies.Peer reviewe

Smart Energy Systems: using IoT Embedded Architectures for Implementing a Computationally Efficient Synchrophasor Estimator

Energy efficiency is a key challenge to build a sustainable society. It can be declined in variety of ways: for instance, from the reduction of the environmental impact of appliances manufacturing, to the implementation of low-energy communication networks, or the management of the existing infrastructures in a smarter way. The actual direction is the integration of different energy systems with a common management scheme with the aim of harmonizing and integrating different energy systems. In this context, smart cities already envision the use of information communication technologies (ICT) to smartify objects and services, connecting people and machines. An important enabling technology for smart cities is certainly the Internet of Things (IoT). Both smart cities and IoT have been extensively investigated over the last few years, under the influence of European funded projects as well. Smart cities apply communication and networking technologies, very often using the paradigm of IoT, to address relevant issues like traffic congestion, population growth, crowding, and others, besides implementing innovative services, modernizing existing infrastructures, e.g. smart mobility. IoT greatly helps in monitoring and better managing energy consumption as well, realizing smart homes, smart buildings and smart grids. For what concern the power grid, in fact, the direction is to harness IoT technologies to improve flexibility, easiness of use and, ultimately, energy efficiency while preserving stability and safety. Today the electrical grid is facing deep changes, mostly caused by the intensive deployment of Distributed Energy Resources (DER) based on renewable sources such as photovoltaic plants or wind farms. Managing such heterogeneous active distribution networks (ADNs), represent one of the most important challenges to be faced in the future of energy systems. The integration of active elements into the grid is challenging because of both the great potential they bring in energy production and the hazard they may represent if not properly managed (e.g. violation of operational constraints). ADN implementation relies on the deployment of high-performance real-time monitoring and control systems. It is well accepted that the phasor measurement units (PMU) are one of the most promising instruments to overcome many problems in ADN management, as they support a number of applications, such as grid state estimation, topology detection, volt-var optimization and reverse power flow management. However, classic PMUs are conceived to measure synchrophasor in transmission systems, while the distribution ones have very different characteristics and, in general, different needs. Therefore, tailoring the characteristics of the new-generation PMUs to the needs of the ADNs is currently very important. This new kind of PMU must address few important design challenges: 1. improved angle measurement capabilities, to cope with the smaller angle differences that distribution grids exhibit; 2. low cost, to promote an extensive deployment in the grid. These two requirements are clearly in opposition. In this dissertation, a low-cost PMU design approach, partially influenced by IoT ideas, is presented

A Radio-Triggered Wireless Sensor Platform Powered by Soil Bacteria

In the era of the Internet of Things (IoT), where data sensing is expected anywhere and anytime, important issues about energy autonomy of sensors and acquisition systems are still open. This work addresses the problem of powering sensors and transmitting efficiently data on request in a multitude of outdoor/indoor applications, where the presence of soil is considered (e.g., smart farming, home surveillance, smart cities …). We present an ultra-low power wireless architecture, supplied directly by colony of bacteria naturally present in any kind of soil on Earth. The ultra-low power challenges limit the use of wireless communication at the minimum (receiving radio off). Nevertheless, the system is still ready to promptly start any incoming communication thanks to a radio-trigger sub-circuit capable of detecting receiving messages at nearly-zero power consumption

Power Controlling, Monitoring and Routing Center Enabled by a DC-Transformer †

The penetration of various types of renewable sources and on-site storage devices have recently focused attention towards DC power distribution in consumer grids to achieve the target of zero/positive energy buildings and communities. To achieve this target, the most important component is the DC consumer grid architecture which can integrate not only renewable sources and storage, but also enable the implementation in any conventional AC distribution network without any significant upgrade. To this end, a unique DC Transformer enabled DC microgrid architecture is presented in this paper. The architecture, called PCmRC (power controlling monitoring routing center) is proposed to manage distributed energy sources and storage at any stage and also directly interconnects the DC consumer grid with the conventional AC power grid. This paper also investigates detailed control algorithms of each component and the DC Transformer topology in addition to proposing four unique stages of grid operational modes to enhance the overall grid stability in any operational condition. The main objectives are to maximize the exploitation of renewable sources, to decrease reliance on fossil fuels, to boost the overall efficiency of the grid by reducing the power conversion losses and demand side management in all possible forms. The simulation platform is designed in MATLAB/Simulink. Simulation results of several types of case studies show the effectiveness of the proposed power distribution and management model

Plug into a Plant: Using a Plant Microbial Fuel Cell and a Wake-Up Radio for an Energy Neutral Sensing System.

As a step toward sustainable wireless sensing, we present a proof of concept system that uses a Plant Microbial Fuel Cells (PMFC) as a power source. To match the very low power production capabilities of the PMFC, we couple it with an ultra-low power wake-up receiver used as a trigger for sampling and transmission of the sensed value. We demonstrate that this combination, with a new, receiver initiated MAC-level communication protocol, results in a sustainable system for reasonable data rates, shown to be 30s in our laboratory setting. This work offers the first steps toward large-scale wireless sensor networks in applications where the sensors are surrounded by living plants that can provide a green and perpetual power supply

Ultra Low Power Wake-Up Radios: A Hardware and Networking Survey

In wireless environments, transmission and reception costs dominate system power consumption, motivating research effort on new technologies capable of reducing the footprint of the radio, paving the way for the Internet of Things. The most important challenge is to reduce power consumption when receivers are idle, the so called idle-listening cost. One approach proposes switching off the main receiver, then introduces new wake-up circuitry capable of detecting an incoming transmission, discriminating the packet destination using addressing, then switching on the main radio only when required. This wake-up receiver (WuRx) technology represents the ultimate frontier in low power radio communication. In this paper, we present a comprehensive literature review of the research progress in wake-up radio (WuR) hardware and relevant networking software. First, we present an overview of the WuR system architecture, including challenges to hardware design and a comparison of solutions presented throughout the last decade. Next, we present various Medium Access Control (MAC) and routing protocols as well as diverse ways to exploit WuRs, both as an extension of pre-existing protocols and as a new concept to manage low-power networking

A low-voltage measurement testbed for metrological characterization of algorithms for phasor measurement units

In the recent years, the scientific community is paying great attention to the development of phasor measurement units (PMU) and, particularly, to novel digital signal processing algorithms for these instruments. While the performance of estimation algorithms is usually evaluated through simulations on a PC, the overall PMU accuracy depends on measurement hardware as well (e.g., transducers, data converters, and synchronization circuitry). However, the relationship between estimation algorithms accuracy and metrological characteristics of hardware equipment is very difficult to predict or to simulate. Therefore, the performance of different algorithms can be hardly compared when they are actually implemented in real instruments and used in the field. This paper attempts to address this problem by presenting an open testbed for PMU estimation algorithms. The key distinctive feature of the testbed is its ability to evaluate and to compare algorithm accuracy under experimental conditions that include not only the disturbances specified in the IEEE Standard C37.118.1-2011 and its Amendment IEEE C37.118.1a-2014, but also the effects of given uncertainty contributions due to different hardware components. A thorough metrological characterization of the testbed, properly supported by a noise propagation model, is performed in order to quantify such uncertainty contributions and their impact on the estimates of synchrophasor magnitude, phase, fundamental frequency, and rate of change of frequency returned by different algorithms under test. As a case study, three state-of-the-art estimation algorithms are tested in a variety of conditions

A 500 × 500 Pixel Image Sensor with Arbitrary Number of RoIs per Frame and Image Filtering for Center of Mass Estimation

This paper reports on a 500 x 500 pixel CMOS image sensor allowing multiple Regions of Interest (RoI) per frame with programmable number and size, aimed at minimizing the amount of data to be delivered off-chip and at reducing its power consumption. The proposed sensor architecture offers large flexibility to face different use case scenarios and it is suitable to any pixel array. The sensor embeds image background subtraction capability and integrates a computing layer which pre-filters the pixels to estimate the Center of Mass (CoM) of the RoIs up to a maximum size of 128 x 128 pixels. The 8 μm pixel sensor is manufactured in a 110 nm 1P4M CMOS technology and occupies 25 mm2. The chip, operating in standard imaging mode, consumes 4.9 mW at 30 fps