Said Ahzi

• PhD, Habilitation
• Professor at University of Strasbourg

In the work, two morphologies were choosen to represent the Graphene , namely the Ribbon-like and platelet-like geometries. The Eshelby inclusion applied to the Mori-Tanaka micromechanics scheme was used to compute the effective elastic and electroelastic properties of the the composite. The computation process started by implementing the piezoelec...

The present work aimed to study the printability and tensile behaviors of ramie yarn-reinforced PLA-based composites fabricated by an in situ impregnated fused filament fabrication (FFF) process. The dimensional error analysis was conducted to evaluate the printability of biocomposites with different processing variations and continuous ramie yarns...

This work expands upon modeling to compute the average properties of a piezoelectric-based nanocomposite. The modeling was initiated by computing the Eshelby tensors for an anisotropic matrix and which were then implemented into a MATLAB code. The polyvinylidene fluoride (PVDF) is considered as a matrix in which the CNTs are aligned unidirectionall...

Continuous fiber reinforced composites are widely used in thin‐walled structures due to their high specific strength and stiffness. In this work, continuous natural fiber was introduced into thin‐walled biocomposite structures via 3D printing technique to enhance energy absorbing properties and promote ecological compatibility. The effects of varyi...

We recently published a macroscopic virus-centric model to simulate the evolution of the SARS CoV 2 epidemic (COVID 19) at the level of a country or a geographical entity using a new decomposition modeling and machine learning optimization. The approach assumes that an epidemic can be analyzed as the combination of several elementary epidemics repr...

This work reported a novel two-stage in-situ impregnation method for additively manufacturing dry fiber bundles reinforced polymer composites using a commercial dual-nozzle 3D printer. This process allowed simultaneous manufacturing of both continuous fiber prepreg filaments and continuous fiber reinforced polymer composites (CFRPCs). Initially, it...

Fused filament fabrication (FFF) as an additive manufacturing process, is a thermal driven method used to produce continuous fiber reinforced composites for engineering applications. Interlayer delamination is a significant concern for composites manufactured by FFF process. To address the problem of interlayer delamination and enhance the macro-me...

The present work aimed to examine the tensile and flexural behaviors of biocomposites reinforced with continuous plant fibers, utilizing a range of polylactic acid (PLA) matrix materials and varying fiber content. These biocomposites were fabricated using an in situ-impregnated fused filament fabrication (FFF) technique. The study incorporated thre...

3D printing continuous fiber reinforced composite (CFRC) has the advantages of manufacturing complex shapes and short production cycles. Due to the anisotropic mechanical properties of continuous fibers, the printing path of the fibers determines the properties of the printed CFRCs. In this paper, a series of novel cellular crossing paths were prop...

The main goal of this study was to investigate the effect of heat treatment on the microstructural and interlayer mechanical properties of 3D printed continuous carbon fiber‐reinforced composites (CCFRCs). The influence of raster orientations on the interlayer properties of composites was systematically studied by the floating roller peel test. The...

An optimal on-off Air-Conditioner (AC) control scheme, which is proposed to address variable outdoor temperatures under extremely hot weather and desert climate conditions, is studied in this paper. The proposed optimal controller adaptively regulates indoor temperature against outdoors ambient temperature variations based on optimum values generat...

With the growing prominence of environmental conservation awareness, there has been a notable surge in the exploration of renewable materials, particularly in the realm of natural fiber reinforced polymer composites. This heightened focus is underscored by the recent advancements in additive manufacturing techniques dedicated to continuous natural...

The mechanical properties of polymeric membranes are critical factors for a successful and durable application in water treatment technologies. Fabricating membranes with optimal mechanical properties require delicate balancing between material, additives, processing conditions, porosity, and many other variables. Several variables to be optimized...

This paper offered a novel approach for self-monitoring manufacturing damage in 3D printed continuous carbon fiber reinforced composites (CFRCs). The proposed method utilized the Kelvin Four-terminal sensing technique to measure the electrical resistance of continuous carbon fiber bundles within the composites. By employing this measurement approac...

In recent years, innovations in 3D/4D printing techniques for continuous fiber-reinforced polymer composites (CFRPCs) have opened new perspectives for the integrated design and manufacture of composites with customized functions. This paper reviews the current state of 3D/4D printed functional composites, including the materials, shape memory/chang...

In this paper, a novel 3D printed continuous ramie fiber reinforced variable stiffness biocomposite honeycomb cellular structure (CF-VSHS) was reported. Based on the printing path planning of CF-VSHSs, variable stiffness (VS) cellular structures filled with cells of various dimensions were prepared by employing a detachable and recyclable support-a...

The perovskite solar cells (PSCs) are still facing the two main challenges of stability and scalability to meet the requirements for their potential commercialization. Therefore, developing a uniform, efficient, high quality and cost-effective electron transport layer (ETL) thin film to achieve a stable PSC is one of the key factors to address thes...

There is a large amount of oil-contaminated wastewater caused by oil/gas production and marine oil spills. It is still a major challenge for the development of oil/water separating membranes that have excellent separation efficiency, can withstand saline environments, and have long-term durability. We present a new membrane made of ultralong titana...

Perovskite solar cells (PSCs) have gained a tremendous attention from the scientific community due to their huge improvement within the past decade. However, this type of solar cells is still facing significant challenges in terms of stability and scalability. The development and incorporation of a stable, uniform, high-quality and low-cost Electro...

Metal oxides are very appealing materials due to their combined unique properties namely optical transparency and electrical conductivity. Furthermore, metal oxides, as oxide materials, have a high chemical stability which allows a long durability for them as materials and contributes to the durability of the device where employed. SnO2 is a very i...

The mechanical properties of hybrid continuous carbon and Kevlar fibers reinforced polyamide (PA)‐based composites manufactured by the fused deposition modeling (FDM) technique were investigated in this paper. The effects of fiber raster orientations, fiber layer locations, and stacking sequences were studied by the quasi‐static indentation (QSI) t...

This work reported a novel dual-nozzle 3D printing method for continuous fiber reinforced composite cellular structures (CFRSs). The dual-nozzle modules and corresponded printing paths were proposed to realize the CFRSs by theoretically increasing two times manufacturing speed. Based on this novel dual-nozzle 3D printing method, typical rhombus fil...

Fused deposition modeling (FDM) is a promising additive manufacturing technique for fabrication of continuous fiber-reinforced thermoplastic composites. For composite applications, the balance of material properties, including rigidity and toughness, needs to be considered. To overcome the drawbacks induced by single continuous fiber reinforcement,...

Photovoltaic (PV) systems deployed in harsh desert climates, such as those prevalent in the Middle East and North Africa regions, are subject to severe operating conditions: high temperatures, high humidity, heavy soiling, and higher daily/seasonal temperature variations. Added to this are the consequences of climate change such as rising temperatu...

Continuous fiber reinforced composite lightweight structures (CFRSs) are widely applied to aerospace, automobile, marine and other fields due to their high specific strength and modulus, low density and fatigue resistance. Innovations in the additive manufacturing technique of continuous fiber reinforced composites (CFRC) opened new perspectives fo...

In the present work, we report on the microstructural and optoelectronic properties of SnOx thin films deposited by a reactive radio frequency magnetron sputtering. After SnOx growth by sputtering under O2/Ar flow, we have used three different treatment methods, namely (1) as deposited films under O2/Ar, (2) vacuum annealed films ex-situ, and (3) a...

The mechanical properties of polymeric membranes are very important in water treatment applications. In this study, polysulfone (PSF) membranes with different loadings of cellulose nanofibers (CNFs) were prepared via the phase inversion method. CNF was characterized through transmission electron microscopy (TEM) and scanning electron microscopy (SE...

3D printing using continuous fiber reinforcement provides a new technical method for preparing complex components with high mechanical behaviors. However, these printed composites have great differences in interfacial behaviors, affecting overall performance. This study aimed to investigate the tensile behaviors of 3D printed continuous fiber fille...

3D-printed continuous ramie fiber reinforced polypropylene composites (CRFRPP) are expected to ensure good mechanical properties while meeting the requirements of environmental friendliness and sustainability. To promote the wide industrial application of CRFRPP, this work investigated the effects of printing parameters (extrusion flow rate, printi...

3D printing technologies are widely used in aerospace, automobile, and other fields due to their rapid manufacture of strong and lightweight products without additional molds and components. However, the relatively low mechanical behaviors of 3D printed composites were due to the weak pristine matrix and the inherent porosity of the fused depositio...

Photovoltaic (PV) systems deployed in harsh desert climates, such as those prevalent in the Middle East and North Africa regions, are subject to severe operating conditions: high temperatures, high humidity, heavy soiling, and higher daily/seasonal temperature variations. Added to this are the consequences of climate change such as rising temperatu...

3D‐printed continuous natural fiber reinforced biocomposites have promising prospects due to their environmental friendliness and suitable mechanical properties. Understanding the dynamic mechanical properties of 3D‐printed biocomposites is essential to expand their application. In this study, the continuous ramie fiber reinforced biocomposites (CR...

This study aimed at applying machine learning (ML) methods to analyze dynamic strength of 3D-printed polypropylene (PP)-based composites. The dynamic strength of additive manufactured PP-based composites with different fillers and printing parameters was investigated by split Hopkinson pressure bars. Based on experimental results, six machine learn...

Continuous fiber reinforced polymers composites have significant potential due to their high specific strength and high specific modulus. But there are some limitations on manufacturing and maintenance for the composites using existing manufacturing technologies. Meanwhile, the increasingly advanced 3D printing technology, with advantages on comple...

Porous polymer-based nanocomposites have been used for various applications due to their advantages, including multi-functionalities, easy and known manufacturability, and low cost. Understanding of their mechanical properties has become essential to expand the nanocomposites’ applications and efficiency, including service-life, resistance to diffe...

This work aimed to investigate progressive collapse behaviors and mechanisms of the 3D printed thin-walled composite structures under quasi-static compression and dynamic impact conditions. The thin-walled structures were manufactured by fused deposition modeling technique, using polyamide and fiber-reinforced polyamide-based composite. Four kinds...

3D-printed composites have promising potential for applications as structural or functional parts in different engineering fields. However, due to the presence of pores and weak interface interactions, 3D-printed parts have weaker mechanical performance than traditional processed ones. In recent years, polypropylene (PP) emerged as a new 3D printin...

Numerous models have been developed in the literature to simulate the thermomechanical behavior of amorphous polymer at large strain. These models generally show a good agreement with experimental results when the material is submitted to uniaxial loadings (tension or compression) or in case of shear loadings. However, this agreement is highly degr...

Agricultural crops such as vegetal fiber are increasingly used for composite reinforcement, but additive manufacturing of biocomposite using vegetal fibers still needs to be developed. The present work aimed to study the mechanical properties and interfacial analysis of 3D printed continuous vegetal fiber reinforced biomass based composites. The bi...

In this work, we study Plasma Post Treatment (PPT) effect on nitrogen doping for sputtered SnOx to achieve a p-type semiconductor using PECVD set-up at six different conditions. Process gases used in PPT are NH3, N2O and N2. These nitrogen precursor gases can be decomposed by RF-plasma and release N ions, which will be incorporated within SnOx. The...

In this paper, based on Huang's bridging model (Huang Z-M, 2001), an effective and concise analytical prediction scheme for effective elastic properties of fuzzy fiber reinforced composites' (FFRCs), is presented. The distinctive constructional feature of the FFRCs, herein, is that the fuzzy fibers are continuous, aligned, and having wavy nanofille...

In the present study, polysulfone (PSF) ultrafiltration membranes incorporated with varying amounts of halloysite nanotubes (Hal) were fabricated via immersion precipitation membrane casting technique. Membrane characterization by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM) revealed th...

A typical photovoltaic (PV) module is composed of different layers bonded together, each with a different material and thus, a different coefficient of thermal expansion (CTE). While under operation, it is subjected to thermal loads due to continuous temperature variations. The CTE mismatch induces thermo-mechanical stresses, whose cyclic nature ca...

Numerous models have been developed in the literature to simulate the thermomechanical behavior of amorphous polymer at large strain. These models generally show a good agreement with experimental results when the material is submitted to uniaxial loadings (tension or compression) or in case of shear loadings. However, this agreement is highly degr...

We report a method to model, simulate and predict high-level nuclear waste (HLW) thermal behavior over short and long time-scales. The approach relies on an inverse method using homogenized thermal fluxes at the HLW package surfaces during the vitrification process. The thermal simulation can then be used as input in subsequent structural analyses....

Micro-voids are common imperfections generated during manufacturing or prolonged service of composites. The present paper emphasizes on the effect of not only matrix-pores, but also the interphase-defects on the effective stiffness of unidirectional fiber-reinforced composites (UFRCs). To this aim, a hierarchical modeling of porous UFRCs is establi...

In this study, models are developed to predict the mechanical behavior of porous polymer‐based membranes, since they are exposed to temperature and pressure load under service conditions. To the best of our knowledge, existing studies related to numerical simulations of mechanical behavior of polymer nanocomposites do not explicitly report porosity...

The high-voltage spinel LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material for next generation lithium-ion batteries for fast charge-discharge applications, but its capacity decay mechanism and rate-limiting process are not yet well understood. In this study, electrochemical impedance spectroscopy with galvanostatic intermittent titration (GITT)...

Although it is still a great challenge, developing oil-/water-separating membranes that combine the advantages of high separation efficiency, salty environments tolerance, and fouling resistance are highly demanded for marine oil spill cleanups and oil-/gas-produced water treatment. Here, we report a new type of all-inorganic nanostructured membran...

Recently boron nitride received a lot of attention due to its applications in optoelectronic devices, multi-function composites, and biological materials. Using first-principles calculations, we show that the band gap in aluminum doped two-dimensional hexagonal boron nitride (2D-h-BN) layers strongly depends on Al concentration. We found that incre...

Being reliant on Air Conditioning (AC) throughout the majority of the year, desert countries with extremely hot weather conditions such as Qatar are facing challenges in lowering weariness cost due to AC On-Off switching while maintaining an adequate level of comfort under a wide-range of ambient temperature variations. To address these challenges,...

Adhesively bonded joints using epoxy resin are nowadays often replacing welding in offshore applications for safety reasons. During its lifetime, the bonded joint epoxy is submitted to severe environmental and loading conditions, such as humidity, water uptake, thermal aging, and complex loading conditions affecting its mechanical performance. We i...

In the present study, nanocomposite ultrafiltration membranes were prepared by incorporating nanotubes clay halloysite (HNTs) into polysulfone (PSF) and PSF/polyvinylpyrrolidone (PVP) dope solutions followed by membrane casting using phase inversion method. Characterization of HNTs were conducted using scanning electron microscopy (SEM), transmissi...

Short-fiber-reinforced thermoplastics are popular for improving the mechanical properties exhibited by pristine thermoplastic materials. Due to the inherent conflict between strength and ductility, there are only a few successful cases of simultaneous enhancement of these two properties in polymer composite components. The objective of this work wa...

Photovoltaic (PV) soiling experiments under extreme desert soiling conditions are used to explore and analyze the soiling rate variations over long-term operations, i.e. 6 years. The electrical yield, for several c-Si, CdS/CdTe and CIS PV arrays, is investigated over a wide range of accumulated dust soiling. Although the dust soiling is accumulatin...

Crystalline silicon (c-Si) technology, including monofacial and bifacial, currently accounts for 96% of the total global annual PV production. In Qatar, the bifacial configuration is capable of producing up to 40% more electrical power compared to its monofacial counterpart, under the same field conditions. Owing to this huge chunk of share in the...

The SnOx films were synthetized in two steps. First step consists of RF sputtering using high purity (99.99%) SnO target on quartz substrates at 250°C, and using different O2 flow rates. The second step consists of two different post deposition annealing at 400°C, one in air and the other one under a moderated vacuum. The best conductive thin film...

Les matériaux polymères sont connus pour avoir un comportement thermomécanique complexe, fortement dépendant de la température et de la vitesse de déformation. De nombreuses études expérimentales, théoriques et numériques ont été développées pour comprendre et approcher leur comportement en petites et grandes déformations [1-5]. Ces modèles sont le...

Sustainable development and effective management of resources has become an integral need of future energy systems. This study considers a unique multi-generation system involving ammonia synthesis using electro-lytically produced hydrogen from desalinated water, alongside supply of basic utilities like potable water, heating, cooling, and electric...

The effect of reprocessing on the quasi-static uniaxial tensile behavior of two commercial polypropylene (PP)-based composites is experimentally investigated and modeled. In particular, the studied materials consist of an unfilled high-impact PP and a talc-filled high-impact PP. These PP composites are subjected to repeated processing cycles, inclu...

The effect of reprocessing on the quasi-static uniaxial tensile behavior of two commercial polypropylene (PP) based composites is experimentally investigated and modeled. In particular, the studied materials consist of an unfilled high-impact PP and a talc-filled high-impact PP. These PP composites are subjected to repeated processing cycles includ...

The electrical performance of a photovoltaic (PV) panel is based on its power conversion efficiency, which is inversely proportional to its operating temperature. Using a self-developed numerical thermal model, the performance of a silicon-based one-sun commercial PV panel has been analyzed by varying different physical and environmental factors. T...

Nanoporous graphene (NPG), consisting of ordered arrays of nanopores separated by graphene nanoribbons was recently realized using a bottom-up synthesis method (Science 360(2018), 199). In this work we accordingly explored the mechanical response, thermal conductivity and electronic/optical properties of single-layer NPG using the density functiona...

Excess phosphate in water is known to cause eutrophication, and its removal is imperative. Nanoclay minerals are widely used in environmental remediation due to their low-cost, adequate availability, environmental compatibility, and adsorption efficiency. However, the removal of anions with nanoclays is not very effective because of electrostatic r...

In amorphous polymers, the yield stress is strongly dependent on strain rate and temperature. It is demonstrated that the influence of strain rate and temperature can be studied from a thermodynamic point of view by defining activation parameters. These parameters allow for understanding the mechanisms that take place during plastic yielding. A com...

Nanoporous graphene (NPG), consisting of ordered arrays of nanopores separated by graphene nanoribbons was recently realized using a bottom-up synthesis method (Science 360(2018), 199). In this work we accordingly explored the mechanical response, thermal conductivity and electronic/optical properties of single-layer NPG using the density functiona...

The batteries used with standalone PV systems are very sensitive to the current-voltage charging. Thus, for choosing the right battery, a PV system designer needs to make an accurate estimate of the current and voltage outputs of the PV module under consideration. However, this task is challenging due to randomness in the field operating conditions...

Groundwater recharge from rainfall is a major input into aquifers, especially in arid and semi-arid areas, where little or no surface water exist. However, estimation of rainfall recharge is not an easy task as it is highly variable spatially and temporally. In arid areas, recharge occurs indirectly after rainfall-runoff accumulates in low lands su...

Due to intrinsic nature of photovoltaic (PV) cells, they can utilize only a small portion of the incident solar spectrum for photoelectric conversion. The unutilized energy builds up inside the PV cells, which in turn raises their working temperature and reduces their electrical conversion efficiency. This indicates that higher temperatures have an...

A precise estimate of PV panels temperature is crucial for accurately assessing their electrical performance. Therefore, in this study, one of the main aims has been to significantly improve the prediction accuracy of the PV cell temperature, by using realistic boundary conditions. Unlike previous thermal models in the literature, which usually foc...

Plasticization of polymers largely contributed to their worldwide utilization, especially for automotive crashworthiness, by making them a more ductile material. For such applications, a clear understanding of the mechanical properties evolution over a large range of strain rate and temperature is needed. In this study, we investigate a plasticized...

Since the first report of graphdiyne nanomembranes synthesis in 2010, different novel graphdiyne nanosheets have been fabricated. In a latest experimental advance, triphenylene-graphdiyne (TpG), a novel two-dimensional (2D) material was fabricated using the liquid/liquid interfacial method. In this study, we employed extensive first-principles simu...

PV system performance measures: > Radiation plus Optical performance – via spectrum losses > Thermal performance – via PV cell temperature > Electrical performance – via power output

Poster presented at EUPVSEC 2018. Work in the continuity with our IRSEC'17 proceedings paper. [Figures not mishandled by powerpoint, which happened when uploaded as limited size file on the conference website ( https://www.eupvsec-proceedings.com/proceedings/checkout.html?poster=45831 )]

The aim of the present work was to study the synergistic reinforcement, by short and continuous carbon fibers, of polyamide-based composites. The three-phase composites were obtained by the fused filament fabrication process where short fiber reinforced polyamide was deposited/printed along with continuous carbon fibers in a layered structure. The...

Since the first report of graphdiyne nanomembranes synthesis in 2010, different novel graphdiyne nanosheets have been fabricated. In a latest experimental advance, triphenylene-graphdiyne (TpG), a novel two-dimensional (2D) material was fabricated using the liquid/liquid interfacial method. In this study, we employed extensive first-principles simu...

In this study, a comprehensive energy and exergy analysis of a new multi-generation system using biomass and solar energy is carried out. The proposed system provides five useful outputs namely; electricity, heating, cooling, ammonia synthesis and desalinated water for the Gwadar port of Pakistan. The integrated system uses phase change material (P...

The Cooperative–Viscoplasticity theory based on overstress (VBO) theory which is initially developed for polymers is modified to model the mechanical behavior of graphene-polymer nanocomposites. The modifications are proposed for both the elastic and viscoplastic deformation. For the elastic contribution, an effective modulus definition which cover...

PCMs show great promise as thermal energy storage (TES) medium; however, their low thermal conductivity presents a major bottleneck for their potential application. Enhancement of the thermal conductivity of a paraffin based PCM material using GNP in combination with CNF, CNTs and TRG was investigated in this work. SEM was used to qualitatively ass...