Interpolation et méthodes à haute résolution pour antennes non uniformes

Le travail présenté dans ce papier se rapporte à l'application et le développement de méthodes de localisation de sources pour les antennes non uniformes. Il s'agit en particulier de l'adaptation des méthodes à haute résolution pour les Antennes Linéaires Non Uniformes (ALNU) afin de réaliser l'estimation de direction d'arrivée. Pour se faire une méthode d'interpolation spatiale est mise en oeuvre. L'objet de ce papier est de comparer les performances de ces différentes méthodes et d'évaluer la sensibilité des méthodes au choix des paramètres de l'interpolateur

An Improved Wavelet‐Based Multivariable Fault Detection Scheme

Data observed from environmental and engineering processes are usually noisy and correlated in time, which makes the fault detection more difficult as the presence of noise degrades fault detection quality. Multiscale representation of data using wavelets is a powerful feature extraction tool that is well suited to denoising and decorrelating time series data. In this chapter, we combine the advantages of multiscale partial least squares (MSPLSs) modeling with those of the univariate EWMA (exponentially weighted moving average) monitoring chart, which results in an improved fault detection system, especially for detecting small faults in highly correlated, multivariate data. Toward this end, we applied EWMA chart to the output residuals obtained from MSPLS model. It is shown through simulated distillation column data the significant improvement in fault detection can be obtained by using the proposed methods as compared to the use of the conventional partial least square (PLS)‐based Q and EWMA methods and MSPLS‐based Q method

Forecasting of Photovoltaic Solar Power Production Using LSTM Approach

Solar-based energy is becoming one of the most promising sources for producing power for residential, commercial, and industrial applications. Energy production based on solar photovoltaic (PV) systems has gained much attention from researchers and practitioners recently due to its desirable characteristics. However, the main difficulty in solar energy production is the volatility intermittent of photovoltaic system power generation, which is mainly due to weather conditions. For the large-scale solar farms, the power imbalance of the photovoltaic system may cause a significant loss in their economical profit. Accurate forecasting of the power output of PV systems in a short term is of great importance for daily/hourly efficient management of power grid production, delivery, and storage, as well as for decision-making on the energy market. The aim of this chapter is to provide reliable short-term forecasting of power generation of PV solar systems. Specifically, this chapter presents a long short-term memory (LSTM)-based deep learning approach for forecasting power generation of a PV system. This is motivated by the desirable features of LSTM to describe dependencies in time series data. The performance of the algorithm is evaluated using data from a 9 MWp grid-connected plant. Results show promising power forecasting results of LSTM

Statistical fault detection in photovoltaic systems

Faults in photovoltaic (PV) systems, which can result in energy loss, system shutdown or even serious safety breaches, are often difficult to avoid. Fault detection in such systems is imperative to improve their reliability, productivity, safety and efficiency. Here, an innovative model-based fault-detection approach for early detection of shading of PV modules and faults on the direct current (DC) side of PV systems is proposed. This approach combines the flexibility, and simplicity of a one-diode model with the extended capacity of an exponentially weighted moving average (EWMA) control chart to detect incipient changes in a PV system. The one-diode model, which is easily calibrated due to its limited calibration parameters, is used to predict the healthy PV array’s maximum power coordinates of current, voltage and power using measured temperatures and irradiances. Residuals, which capture the difference between the measurements and the predictions of the one-diode model, are generated and used as fault indicators. Then, the EWMA monitoring chart is applied on the uncorrelated residuals obtained from the one-diode model to detect and identify the type of fault. Actual data from the grid-connected PV system installed at the Renewable Energy Development Center, Algeria, are used to assess the performance of the proposed approach. Results show that the proposed approach successfully monitors the DC side of PV systems and detects temporary shading.Peer ReviewedPostprint (author's final draft

Ozone measurements monitoring using data-based approach

The complexity of ozone (O 3 ) formation mechanisms in the troposphere makes the fast and accurate modeling of ozone very challenging. In the absence of a process model, principal component analysis (PCA) has been extensively used as a data-based monitoring technique for highly correlated process variables; however, conventional PCA-based detection indices often fail to detect small or moderate anomalies. In this work, we propose an innovative method for detecting small anomalies in highly correlated multivariate data. The developed method combines the multivariate exponentially weighted moving average (MEWMA) monitoring scheme with PCA modeling in order to enhance anomaly detection performance. Such a choice is mainly motivated by the greater ability of the MEWMA monitoring scheme to detect small changes in the process mean. The proposed PCA-based MEWMA monitoring scheme is successfully applied to ozone measurements data collected from Upper Normandy region, France, via the network of air quality monitoring stations. The detection results of the proposed method are compared to that declared by Air Normand air monitoring association

Seasonal ARMA-based SPC charts for anomaly detection: Application to emergency department systems

Monitoring complex production systems is primordial to ensure management, reliability and safety as well as maintaining the desired product quality. Early detection of emergent abnormal behaviour in monitored systems allows pre-emptive action to prevent more serious consequences, to improve system operations and to reduce manufacturing and/or service costs. This study reports the design of a new methodology for the detection of abnormal situations based on the integration of time-series analysis models and statistical process control (SPC) tools for the joint development of a monitoring system to help supervising of the behaviour of emergency department services (EDs). The monitoring system developed is able to provide early alerts in the event of abnormal situations. The seasonal autoregressive moving average (SARMA)-based exponentially weighted moving average (EWMA) anomaly detection scheme proposed was successfully applied to the practical data collected from the database of the paediatric emergency department (PED) at Lille regional hospital centre, France. The method developed utilizes SARMA as a modelling framework and EWMA for anomaly detection. The EWMA control chart is applied to the uncorrelated residuals obtained from the SARMA model. The detection results of the EWMA chart are compared with two other commonly applied residual-based tests: a Shewhart individuals chart and a Cumulative Sum (CUSUM) control chart

Physico-mechanical properties of phosphogypsum and black steel slag as aggregate for bentonite-lime based materials

This study aim to valorizing phosphogypsum (PG) and steel slag (Sc) in geotechnical applications by incorporating them in bentonite (B) stabilized by lime (L). Mineralogical (XRD), spectroscopic (IR-FTIR), geotechnical (Atterberg limits) analyzes were carried out on the raw material. Resistance to axial compression (UCS) was performed on cylindrical specimens prepared for mixtures B-L, B-L-PG, B-L-PG-Sc and cured for 3, 7, 15 and 28 days. The results obtained revealed that the mechanical strength increases with the addition of PG, and reaches its maximum value for a water content equal to 46%. Slag improves the strength of the B-L-PG mixture. The pH and the electrical conductivity of the solutions containing in porosity of the various mixtures decrease over time. The observed decrease is greatest for B-L-PG and B-L-PG-Sc mixtures due to pozzolanic reactions

Phosphogypsum and Black Steel Slag as Additives for Ecological Bentonite-Based Materials: Microstructure and Characterization

peer reviewedThe Black Steel slag (Ss) and phosphogypsum (PG) are industrial wastes produced in Morocco. In order to reduce these two wastes and to evaluate their pozzolanic reactivity in the presence of water, they were incorporated into bentonite (B) mixed with lime (L). The studied mixtures (BLW, BL–PG–W and BL–PG–Ss–W) were analyzed by X-ray diffraction, Infrared spectroscopy, Raman spectroscopy and SEM/EDX analysis. Compressive strength tests were performed on hardened specimens. The results obtained show that the hydration kinetics of the B–L–W and B–L–PG–W mixtures are slow. The addition of PG to a bentonite––lime mixture induces the formation of new microstructures such as hydrated calcium silicate (C–S–H) and ettringite, which increases the compressive strength of the cementitious specimens. The addition of the Ss to a mixture composed of 8%PG and 8%L–B accelerates the kinetics of hydration and activates the pozzolanic reaction. The presence of C2S in the slag helps to increase the mechanical strength of the mixture B–L–PG–Ss. The compressive strength of the mixtures BL–W, BL–PG–W and BL–PG–Ss–W increases from 15 to 28 days of setting. After 28 days of setting, 8% of Sc added to the mixture 8% PG–8%L–B is responsible for an increase of the compressive strength to 0.6 MPa

Reduction of phosphogypsum to calcium sulfide (CaS) using metallic iron in a hydrochloric acid medium

peer reviewedOur study aims to decompose phosphogypsum (PG), mainly composed of CaSO4.2H2O, by reduction in an acidic medium. We evaluated the decomposition of PG by various reaction mechanisms. Sulfate ions from the acid digestion of PG are reduced to sulfide by the hydrogen gas produced in the solution by hydrochloric attack of the metal iron. The solid residues obtained have been determined and monitored by X-Ray Diffraction, Fourier-Transform Infrared spectroscopy and Ultraviolet-visible spectroscopy. The microstructure of residues was observed by scanning electron microscope (SEM). The results show that hydrogen gas formed by hydrochloric acid attack of iron reduces the sulfur from S(VI) to S(-II). CaSO4.2H2O, insoluble in water, gives a residue containing CaS, which is only sparingly soluble in water. The residue also contains anhydrite, bassanite and ferrous chloride. The monitoring of the quantities of residue obtained under varying experimental conditions (temperature, attack time, mass of iron and PG and volume of acid on PG) and volume of HCl showed that the amounts of residue obtained are less than 32% of mass. When the volume of the HCl added increases, the obtained mass of the solid residue decreases sharply. The residue stabilizes at 10% of mass when the volume of HCl added is higher than that required to attack metal iron