Liste des communications
Bidirectional Charging Impact Analysis of Electric Vehicle Battery Cycle Aging Evaluation in Real World, Under Electric Utility Grid Operation
This scientific article examines the integration of electric vehicles (EVs) into electricity grids using Vehicle-to-Grid (V2G) technology. The study compares the economic implications of two EV charging approaches: firm EV charging and managed EV charging. Interestingly, the research finds that the firm EV load is associated with a higher Net Present Cost (NPC) compared to the managed charging load, highlighting the economic benefits of the latter approach. The facility being studied consumes 26,498 kWh of electricity daily and has a peak demand of 2,022 kW. To meet its electricity needs, the proposed system incorporates several generation sources, notably a Canadian Solar PV system with a nominal capacity of 4,000 kW and a Tesla storage system with a nominal capacity of 10,079 kWh. These sources produce an annual total of 6,918,968 kWh. Additionally, the study evaluates two tariff plans, with a focus on the 'EV' tariff. The analysis reveals that adopting the 'EV' tariff can result in significant cost savings for the hospital. However, it emphasizes that the hospital must individually meter its EV charging station to qualify for this advantageous tariff. Furthermore, the research addresses the issue of EV battery degradation, particularly concerning its implications for V2G technology integration. Despite widespread concerns, empirical evidence in various grid service contexts is limited. To address this gap, the paper introduces a comprehensive method to quantify EV battery degradation. A unique aspect of this approach is its multiyear perspective, enabling a robust comparison of scenarios involving driving alone and those incorporating multiple vehicle-grid services. This innovative methodology provides valuable insights into the complex relationship between EV battery degradation and the evolving energy landscape. Voir les détails
Mots clés : Firm EV, Managed EV, Tesla storage, Multi-year planning, degradation, PV
Temperature and Cycling Effect on Microgrid Advanced Li-ion Battery Storage: Efficient Multi-Year Technical Energy Planning- a Case Study-
This study focuses on the optimization of a microgrid solution designed for a real-world location (Adrar), with a specific emphasis on the dynamic changes in the integrated Li-ion battery performances, particularly on time-temperature effects and cycling degradation over the system's lifetime. We meticulously evaluate various scenarios, including different combinations of energy sources such as solar photovoltaics (PV), a diesel engine backup system, and Li-ion battery storage for off-grid applications. The research employs an innovative approach, incorporating a multiyear growth method and conducting indepth technical analyses using the Hybrid Optimization Model for Electric Renewables software to pinpoint the most efficient energy system. The analysis extends across a 20-year, simulating each time step throughout the project's lifespan. These factors are crucial in optimizing the microgrid's long-term sustainability. Although this approach demands additional computational time, it ensures the development of a highly accurate model. Initially, we conducted model runs without multi-year optimization, relying on the Optimizer to identify the optimal system configuration. The outcome reveals an ideal system composed of a Danvest generator with a capacity of 760 kW, 200 kWh of Li-ion storage, and a competitive levelized cost of electricity (COE) at $0.309 per kWh for the one-year model. This integrated microgrid design offers valuable insights into the potential of Li-ion batteries as a crucial component in achieving efficient and sustainable energy solutions for real-world applications. Voir les détails
Mots clés : Li-ion, Microgrid, Multi-year planning, Technical optimization, PV, Diesel, Hybrid energy system
Fatigue-Induced Effects of Prolonged Holding Time on Corrosion in AISI 4130 Steels Welded with a Nickel-based Electrode via the Pulsed TIG Process
The maintenance of blowout preventers (BOPs) used in the hydrocarbon field requires the use of a material with good mechanical and corrosion resistance properties. In the present study, the impact of fatigue-inducing holding times ranging from 1 to 3 hours during post-weld heat treatment (PWHT) at 640°C on the electrochemical behavior and mechanical properties of AISI 4130 steel substrate overlaid with a nickel-based alloy is investigated. The overlay was achieved using the pulsed Tungsten inert gas (TIG-Pulsed) process. The results indicated that, as the fatigue-inducing holding time increased beyond 3 hours, the hardness of the substrate/surface interface decreased. This phenomenon can be attributed to the release of thermal stress resulting from the weld overlay operation. Additionally, electrochemical impedance spectroscopy (EIS) measurements were conducted in a 2.5% NaCl solution, revealing a capacitive effect in the low-frequency region due to the precipitation of a new film that modified the surface properties. In contrast, potentiodynamic tests indicated that the open circuit potential (Ecorr) became more stable or positive with an increased fatigue-inducing holding time. Voir les détails
Mots clés : AISI4130, holding time, TIG-Pulsed, corrosion, hard facing operation
X-Ray Image Restoration in the Wavelet Domain
Wavelet expansions and wavelet transforms haveproven to be very efficient and effective in analyzing a verywide class of signals and phenomena. Wavelet expansion allowsa more accurate local description and separation of signalcharacteristics. While Fourier coefficient represents acomponent that lasts for all time, a wavelet expansioncoefficient represents a component that is itself local and iseasier to interpret. In this work, we have used images obtainedby the microfocus radioscopy system for the quality control ofthe metallization step of silicon solar cells. In many systems, theobserved image can result from the convolution of the trueimage and the point spread function (PSF) contaminated bynoise from various sources. The goal of this paper is toinvestigate the discrete wavelet transform (DWT) and itsapplication to X-Ray image denoising Voir les détails
Mots clés : discrete wavelet transform (DWT), image denoising, wavelet, X-ray
PATTERN RECOGNITION IN ULTRASONIC IMAGERY USING THE HOUGH TRANSFORM
In non destructive testing of materials, the ultrasonic imagery is a field in full rise. Indeed , more than one convivial representation of the results , the operations of detection , localization and sizing of the defects can be carried out automatically by the analysis of synthesized images. The problem breaks up in general into a phase of preprocessing to only limit the quantity of information to useful and a processing phase in order to characterize the defect. In our article, we will briefly describe the the ultrasonic images formation said C-SCAN and TOFD, before seeing how a high pass filtering makes it possible to reduce the image c-scan to the only points of the defect edges. This preprocessing reduces considerably calculations for using the Hough transform in patterns recognition of defects in the case of C-SCAN image , and the localization of cracks in the case of the TOFD image Voir les détails
Mots clés : Non destructive testing, Ultrasonic imagery, Edge detection, Hough transform
Experimental study and simulation of stable phase β (mg2si) evolution during artificial aging of aluminum alloy AA6005
An AA6005 alloy that has been machined or cast can be strengthened using various aging and solution heat treatment techniques. This is called structural precipitation hardening which goes through three steps ،a homogenization at lower temperature of melting temperature, which ensures alloy solution and then rapid cooling, and finally an aging treatment at a temperature between 180°C and 220°C for our alloys. In order to optimize the time and number of heat treatments, we perform simulations of various heat treatment ranges using MatCalc software to initiate precipitation reactions → G zone. P.→ β″→ β′→β (Mg2Si). Artificial aging is used to induce the formation of the hardening phases (Mg2Si). The MatCalc software uses the mc Al.ddb thermodynamic database for aluminum alloys. The numerical results are in good agreement with the microhardness results, which demonstrate the existence of the stable β phase Voir les détails
Mots clés : simulations, AA6005, artificial aging
Finite element investigation of the elasto-plastic behavior of AA6005 using the Hansel-Spittel rheological model and the Cockcroft and Latham fracture model
Understanding the behavior of materials requires accurate and expensive mechanical tests at different temperatures and stresses. The current trend toward numerical simulation has become an essential engineering tool. Therefore, researchers have made efforts in this area by building mathematical models based on experimental data. These models include data regarding the actual physical behavior of the material, such as its temperature sensitivity, strain rate sensitivity, and strain sensitivity. The constitutive equations of Hensel and Spittel (H-S) [1] have been frequently used (FES), due to their ease of numerical implementation, the inclusion of stress and strain history, and the calibration of parameters from tests. The objective of this work is to determine the mechanical characteristics of the aluminum alloy (AA 6005), taking into account the effect of work hardening. This behavior is then tested using finite element analysis tools to model it. The experimental results showed that the work-hardening behavior of the alloy (AA 6005) at room temperature is similar to all quasi-static strain rates studied in this work. In addition, in the range of strain rates investigated in this study, the finite element results correlate well with the experimental results. The simulated results can be really reliable only when a good constitutive equation is employed. Voir les détails
Mots clés : tensile test, rheological behavior Hasel-Spittel, Ductile Damage Fracture criterion
Modeling Cracks Using Digital Images Correlation and Phase-Field FE Analysis Techniques
In this work, the recently developed phase field fracture along with digital images correlation DIC techniques are used to study mode I crack behavior, an elastic brittle phase field model which is well implemented in some finite elements codes is used, in this model the damage evolution is driven only by elastic strains and is governed by the classical brittle phase-field law, the opensource digital images correlation Ncorr code is used to extract full displacement and strain field from experiments, this open-source DIC code can treats cracks in structure by taking into account discontinuities through the sub-sets, the discontinuities in the displacement field are well captured and used in the out-puts to compute the size of crack by tracking and locating the position of the crack tip, the best results are obtained by finding the smallest DIC parameters (sub-sets size and radius) which gives results without noise. Results are expressed in term of plots of displacement vs reaction-force, contour plots of displacement and strain field components, crack tip opening displacement and fracture path tracking. Results from both approaches are presented and then a discussed is conducted to show the capabilities of both methods to study and track crack evolution in structures under mode I loading. Voir les détails
Mots clés : Cracks, Finite Element Analysis, Phase Field Fracture, Digital Images Correlation, Ncorr
Characterization of an ultrasound reception chain based of a PVDF membrane hydrophone
Ultrasound is commonly used in different applications such as the defects detection in materials, underwater detection, medical and biological applications. In all this applications, it is necessary to have a system allowing the emission of ultrasonic waves and their reception. In general, this system is essentially composed of an electric generator, a transmitter transducer, a receiver transducer and a display or recording system. The purpose of this work is the functioning characterization of a measurement chain comprising a receiver transducer with PVDF membrane connected by means of a coaxial cable to an oscilloscope. This theoretical model proposed, allows the determination of the impulse response in the temporal domain or the transfer function in the frequency domain of the entire reception measurement chain. In this study, special attention is given to the receiving transducer as the main element of the receiving chain. Voir les détails
Mots clés : PVDF membrane, ultrasound reception chain, transfer function, impulse response, transfer Matrix
Damage Analysis In Open Hole Composite Specimens By Acoustic Emission: Experimental Investigation
In the present work, an experimental study is carried out using acoustic emission and DIC techniques to analyze the damage of open hole woven composite carbon/epoxy under solicitations. Damage mechanisms were identified based on acoustic emission parameters such as amplitude, energy, and cumulative account and rise time. The findings of the AE measurement were successfully identified by digital image correlation (DIC) measurements. The evolution value of bolt angle inclination during tensile tests was studied and analyzed. Consequently, the relationship between the bolts inclinations angles during tensile tests associated with failure modes of composite materials fastened joints is determined. Moreover, there is an interaction between laminate pattern, laminate thickness, fastener size and type, surface strain concentrations, and out-of-plane displacement. Conclusions are supported by microscopic visualizations of the composite specimen. Voir les détails
Mots clés : damage analysis, composite specimens, acoustic emission