Electrical characterization of the soft breakdown failure mode in MgO layers

The soft breakdown (SBD) failure mode in 20 nm thick MgO dielectric layers grown on Si substrates was investigated. We show that during a constant voltage stress, charge trapping and progressive breakdown coexist, and that the degradation dynamics is captured by a power-law time dependence. We also show that the SBD current-voltage (I-V) characteristics follow the power-law model I = aVb typical of this conduction mechanism but in a wider voltage window than the one reported in the past for SiO2. The relationship between the magnitude of the current and the normalized differential conductance was analyzed

Assessment of the Shellfish Production Areas’ Quality: The Oualidia and Sidi Moussa Lagoons Case

Based on European regulation 91/492/EC, Morocco, very early, established legislation with conditions for producing and marketing live bivalve molluscs. In applying this legislation, the National Institute of Fisheries Research (INRH)   has set up a system for sanitary monitoring of the marine environment, through which several harvesting areas have been classified while others are in progress. In January 2020, the Oualidia and Sidi Moussa lagoons were categorized respectively in classes B and C with respectively 52.77% of the results, which were between 230 and 4600 MPN E. coli / 100 g of flesh and intravalvular liquid (FIL) and 11.11% of results that fell between 4600 and 46000 MPN E. coli / 100 g FIL. Sidi Moussa lagoon has been classified as a clean area category C since 2006. As a result, the oyster farming activity has been suspended in this area. This incident is a warning sign of the significant weakness of these ecosystems in addressing multiple social and economic challenges. On another side, INRH has sufficient data and tools to progress towards a better optimization of the marine environment sanitary monitoring program management

Assessment of the Shellfish Production Areas’ Quality: The Oualidia and Sidi Moussa Lagoons Case

Based on European regulation 91/492/EC, Morocco, very early, established legislation with conditions for producing and marketing live bivalve molluscs. In applying this legislation, the National Institute of Fisheries Research (INRH)   has set up a system for sanitary monitoring of the marine environment, through which several harvesting areas have been classified while others are in progress. In January 2020, the Oualidia and Sidi Moussa lagoons were categorized respectively in classes B and C with respectively 52.77% of the results, which were between 230 and 4600 MPN E. coli / 100 g of flesh and intravalvular liquid (FIL) and 11.11% of results that fell between 4600 and 46000 MPN E. coli / 100 g FIL. Sidi Moussa lagoon has been classified as a clean area category C since 2006. As a result, the oyster farming activity has been suspended in this area. This incident is a warning sign of the significant weakness of these ecosystems in addressing multiple social and economic challenges. On another side, INRH has sufficient data and tools to progress towards a better optimization of the marine environment sanitary monitoring program management

New Paradigms for Access Control in Constrained Environments

International audienceThe Internet of Things (IoT) is here, more than 10 billion units are already connected and five times more devices are expected to be deployed in the next five years. Technological standarization and the management and fostering of rapid innovation by governments are among the main challenges of the IoT. However, security and privacy are the key to make the IoT reliable and trusted. Security mechanisms for the IoT should provide features such as scalability, interoperability and lightness. This paper adresses authentication and access control in the frame of the IoT. It presents Physical Unclonable Functions (PUF), which can provide cheap, secure, tamper-proof secret keys to authentify constrained M2M devices. To be successfully used in the IoT context, this technology needs to be embedded in a standardized identity and access management framework. On the other hand, Embedded Subscriber Identity Module (eSIM) can provide cellular connectivity with scalability, interoperability and standard compliant security protocols. The paper discusses an authorization scheme for a constrained resource server taking advantage of PUF and eSIM features. Concrete IoT uses cases are discussed (SCADA and building automation)

Optimal Load Restoration in Active Distribution Networks Complying with Starting Transients of Induction Motors

Large horsepower induction motors play a critical role as industrial drives in production facilities. The operational safety of distribution networks during the starting transients of these motor loads is a critical concern for the operators. In this paper, an analytical and convex optimization model is derived representing the starting transients of the induction motor in a semi-static fashion. This model is used to find the optimal energization sequence of different loads (static and motor loads) following an outage in a distribution network. The optimization problem includes the optimal control of the converter-based DGs and autotransformers that are used for the induction motor starting. These models together with the semi-static model of the induction motor are integrated into a relaxed power flow formulation resulting in a Mixed-Integer Second Order Cone Programming (SOCP) problem. This formulation represents the transient operational limits that are imposed by different protection devices both in the motor side and network side. The functionality of the proposed optimization problem is evaluated in the case of a large-scale test study and under different simulation scenarios. The feasibility and accuracy of the optimization results are validated using I) off-line time-domain simulations, and II) a Power Hardware-In-the-Loop experiment

Improved piezoelectric properties of PLA/PZT hybrid composite films

Piezoelectric polymer-ceramic composites are promising materials for Sensing, Wireless electronics and actuating applications. We report the fabrication of highly piezoelectric biocompatible films containing lead zirconate titanate (PZT) ferroelectric ceramic particles dispersed in poly lactic acid (PLA) with different volume fractions using a solvent cast technique. The properties of the piezoelectric polymer-ceramic films were investigated by Fourier transform infrared spectrometry (FTIR) and field emission scanning electron microscopy (FE-SEM). In the FTIR spectra appear a large number of absorption bands which are attributed to the phases from PLA matrix confirming the total embedding of PZT filler into the matrix. The SEM results showed a good distribution of fillers in the matrix. We find that the added PZT imposes a significant effect on the α–β phase transformation. Our finding can lead to extraordinary enhancement of piezoelectric properties for the PLA/PZT composite films

Enhancement of power system transient stability using superconducting fault current limiters

Transient stability investigations consist of studying the rotor oscillations of generators (electro-mechanic oscillations, 0.1-2 Hz) after the occurrence of a fault of large amplitude, e.g. short circuit. The goal is to indicate if the generators are capable to stay synchronous after a fault has occurred. The fault duration is one of the most important factors to be determined. In fact, the shorter the fault, the more the maintaining of synchronisation can be guaranteed. Now in case of a fault, a fault current limiter has an extremely fast current transition in comparison to electro-mechanic time constants. This implies a quasi-instantaneous elimination of the fault through a limitation of the current and consequently a better ability to maintain the synchronisation of the system. We recall that in a classic system, the elimination of a fault, by opening a circuit breaker, is carried out in two or three cycles in the best case. We have here studied a simple, radial electric network configuration with a machine and an infinite network. The study covers simulations of a fault that can occur in a network and the consequences of the recovery time of the fault current limiter

Enhanced piezoelectric properties of PVdF-HFP/PZT nanocomposite for energy harvesting application

The use of piezoelectric nanocomposite in detection and actuation applications for the development of electromechanical microsystems (MEMS) has become quite common over the last decade. In this paper, we present a flexible piezoelectric nanocomposite films, composed of lead zirconate titanate (PZT) nanoparticles, embedded in poly(vinylidene-difluoride hexafluoro propylene) (PVdF-HFP) matrix. Piezoelectric and ferroelectric properties evolution is proportional to the evolution of the crystalline β-phase. The evaluation of the interactions between PZT and PVdF- HFP, performed by Fourier transform infrared spectroscopy (FTIR), revealed a dramatic improvement in these characteristics over pure PVdF-HFP, and attributed to a better crystallinity of the PVdF-HFP matrix and uniform distribution of nanoparticles. These films nanocomposites were done by solvent casting method, with various concentrations of PZT. Results of these experiments indicate that the investigated thin films nanocomposites are appropriate for various applications in energy storage and energy harvesting application

An enhanced power harvesting from woven textile using piezoelectric materials

The field of power harvesting has experienced significant growth over the past few years due to the ever-increasing desire to produce portable and wireless electronics with extended lifespans. The present work aims to introduce an approach to harvesting electrical energy from a mechanically excited piezoelectric element and investigates a power analytical model generated by a smart structure of type polyvinylidene fluoride(PVDF) that can be stuck onto fabrics and flexible substrates. Moreover, we report the effects of various substrates and investigates the sticking of these substrates on the characterization of the piezoelectric material

Properties of Cd1-xZnx Te crystals grown by High Pressure Bridgman (HPB)

In this paper we present results of a modelling of the current-voltage characteristics of metal/ultra-thin oxide/semiconductor structures with negatively biased metal gate (V<0), when the oxide thickness varies from 45Å to 80Å. We analyze the theoretical influence of the temperature and Schottky effect on the Fowler-Nordheim (FN) conduction. The results obtained show that these influences depend on the electric field in the oxide and on the potential barrier at the metal/oxide interface. At the ambient temperature, the influence on this potential barrier is lower than 1.5%. However, it can reach 45% on the pre-exponential coefficient of the FN current. It is therefore necessary to consider in the FN classical conduction expression a correction term that takes account the temperature and Schottky effects. These results are validated experimentally by modelling the current-voltage characteristics of the realized structures at high field.In this paper we present results of a modelling of the current-voltage characteristics of metal/ultra-thin oxide/semiconductor structures with negatively biased metal gate (V<0), when the oxide thickness varies from 45Å to 80Å. We analyze the theoretical influence of the temperature and Schottky effect on the Fowler-Nordheim (FN) conduction. The results obtained show that these influences depend on the electric field in the oxide and on the potential barrier at the metal/oxide interface. At the ambient temperature, the influence on this potential barrier is lower than 1.5%. However, it can reach 45% on the pre-exponential coefficient of the FN current. It is therefore necessary to consider in the FN classical conduction expression a correction term that takes account the temperature and Schottky effects. These results are validated experimentally by modelling the current-voltage characteristics of the realized structures at high field